Shielding Structure Of Surface-mount Devices (Electrical Patents)
Abstract
An apparatus and method for shielding for surface-mount LTCC components and filters to increase the signal isolation from input signal port to output signal port, and to increase isolation from other electrical signals external to the component or filter. Some embodiments include an interposer two-sided and plated through printed circuit board to provide a constant impedance transition from a surface-mount device input and output ports to corresponding input and output connection points of a circuit on a printed circuit board onto which the device is mounted, including a ground plane transition.
Claims
1. An apparatus for shielding comprising: a rectangular prism structure having continuous metal around its outer surface, and having at least one side extending to a flat coplanar surface, where said side is solid or has one or more open first apertures to the interior; attachment of said metallic outer surface to one or more metallic attachment points of a device enclosed by a structure; two or more second apertures having relief of said continuous metal on said coplanar surface side extending from the interior to the exterior of said metallic outer surface; one or more geometric features of said metallic outer surface for attachment to metallic elements on a printed circuit board, where said printed circuit board is coplanar with said flat coplanar surface; and said apertures include one or more metallic elements extending from the interior to the exterior of said structure electrically disconnected from said continuous metal, each individually electrically connected to distinct metallic attachment points of said enclosed device, wherein said metallic elements are arranged to form a coaxial electrical signal feed in combination with said metallic surface of said structure; wherein said apparatus further comprising an interposer between said flat coplanar surface and said printed circuit board, wherein said interposer comprises a first aperture and a second aperture, each aperture containing a metallic element arranged to form a coaxial electrical signal feed in combination with said metallic surface of said structure and connected thereto.
2. The apparatus of claim 1, wherein said apparatus is constructed of a non-conductive material and said continuous metal is plated or deposited onto the surface of said structure.
3. The apparatus of claim 2, wherein said metal is plated or deposited both on the exterior surfaces and on the interior surfaces of said structure, and all said plated or deposited metal is electrically connected.
4. The apparatus of claim 1, wherein said enclosed device is selected from a group including a low temperature co-fired ceramic (LTCC) electrical device, a low temperature co-fired ceramic (LTCC) electrical passive circuit or a low temperature co-fired ceramic (LTCC) electrical filter.
5. The apparatus of claim 4, wherein said enclosed device is said low temperature co-fired ceramic (LTCC) electrical filter wherein said continuous metal structure is operable in conjunction with said enclosed LTCC filter to reject additional electrical signal energy directed to pass through a first of said second aperture as an input port, through said enclosed LTCC filter, and subsequently directed to pass through a second of said second aperture as an output port throughout substantially all of the design stopband frequencies of said enclosed LTCC filter, and said rejected additional electrical signal energy is attributable to said electrically connected metallic shielding structure, and wherein said electrical signal energy passing through from said first of said second aperture, through said enclosed LTCC filter and through said second of said second aperture throughout substantially all of the design passband frequencies of said enclosed LTCC filter experiences substantially no additional insertion loss attributable to said continuous metallic structure.
6. The apparatus of claim 4, wherein said metallic attachment points of said device enclosed by said structure are electrically connected to electrical grounding structures within said enclosed LTCC electrical device, and where said electrical grounding structures are comprised of electrically conductive via holes or electrically conductive walled vias.
7. The apparatus of claim 6, wherein said via holes are spaced to be operable as an electrical shielding wall with a distance between successive vias to be reduced to prevent RF electrical signal leakage through said electrical shielding wall according to the frequency of said electrical signal.
8. The apparatus of claim 6, wherein said electrically conductive via holes or said electrically conductive walled vias are orthogonal to said flat coplanar surface.
9. The apparatus of claim 1, wherein said printed circuit board includes a single layer transmission line, wherein said structure includes said metallic elements further arranged for attachment to a multilayer stripline launch, and wherein said interposer attached on a first side to said printed circuit board and attached on a second side to said structure and aligned to use said coaxial electrical signal feed to transfer electrical signal energy between said enclosed device and said transmission line.
10. The apparatus of claim 9, wherein said coaxial electrical signal feed of said interposer further comprises via holes.
11. An apparatus comprising: a metallic rectangular solid structure surrounding a device having continuous metal around its radial circumference, wherein said metallic rectangular solid structure is electrically connected to one or more metallic attachment points of said device enclosed by said metallic rectangular solid structure, and wherein said metallic rectangular solid structure has on at least one side a smooth and flat surface for mounting to a co-planar ground plane of a multilayer stripline launch on a printed circuit board; two or more apertures coplanar to said smooth and flat surface of said metallic rectangular solid structure extending from the interior to the exterior of said metallic rectangular solid structure, each encompassing metallic electrical signal input and output terminal ports electrically connected to corresponding input and output ports of an enclosed a low temperature co-fired ceramic (LTCC) electrical circuit, electrically isolated from said enclosed metallic rectangular solid structure, and arranged for attachment to center conductors of a multilayer stripline launch; said printed circuit board including two or more top-side planar transmission lines, each said transmission line for transfer of electrical signal energy between an electrical circuit on said printed circuit board and said enclosed device; and an interposer having a first side with electrical conductors arranged for attachment to planar transmission lines and attached to said planar transmission lines of said printed circuit board, having a second side with electrical conductors arranged for attachment to a center conductor and a ground plane of a multi-layer stripline and attached to said LTCC center conductors and said LTCC ground plane, and having three or more via holes through said interposer attaching said electrical conductors on said first side to said electrical conductors on said second side.
12. The apparatus of claim 11, wherein said via holes through said interposer are arranged to form a coaxial feed with a coaxial ground plane.
13. A method of constructing an apparatus comprising: constructing a rectangular solid structure surrounding a device having continuous metal around its radial circumference, electrically connecting said metallic rectangular solid structure to one or more metallic attachment points of said device enclosed by said metallic rectangular solid structure, wherein said metallic rectangular solid structure has on at least one side a smooth and flat surface for mounting to a co-planar ground plane of a printed circuit board, and said metallic rectangular solid structure further has two or more apertures coplanar to said smooth and flat surface of said metallic rectangular solid structure extending from the interior to the exterior of said metallic rectangular solid structure, each encompassing a metallic electrical signal terminal port electrically isolated from said metallic rectangular solid structure and electrically connected to a corresponding port of said enclosed device on a first end and arranged for attachment to center conductors of a multilayer stripline launch transmission line on said printed circuit board on a second end; locating an interposer between said metallic rectangular solid structure and said printed circuit board oriented to have alignment with corresponding attachment points to said metallic rectangular solid structure on a first side and to have alignment with corresponding attachment points to said printed circuit board on a second side, wherein said printed circuit board comprises two or more top-side planar transmission lines, each said transmission line for transfer of electrical signal energy between an electrical circuit on said printed circuit board and an electrical device mounted thereon; attaching electrically said interposer on said first side to said metallic rectangular solid structure, wherein said attachment comprises at least one or more electrical attachment to said continuous metal as an electrical ground connection and, wherein at least two or more electrical attachments to said metallic electrical signal terminal ports; and attaching electrically said interposer on said second side to said printed circuit board, wherein said attachment comprises at least one or more electrical attachment by said electrical conductor electrically connected to said electrical ground connection to a ground connection of said printed circuit board top-side planar transmission line ground conductor, and wherein at least two or more electrical attachments by said electrical signal terminal ports electrically connected to two or more corresponding said transmission line center conductors.
14. The method of claim 13, wherein said enclosed device is selected from a low temperature co-fired ceramic (LTCC) electrical device, a low temperature co-fired ceramic (LTCC) electrical passive circuit or a low temperature co-fired ceramic (LTCC) electrical filter.
15. The method of claim 13, wherein said interposer electrically connects between electrical port launches from said metallic rectangular solid structure and said printed circuit board selected from: a coaxial to coaxial transition, a coaxial to co-planar waveguide transition or a coaxial to microstrip transition.
16. The method of claim 13, wherein via holes extend from said first side to said second side of said interposer are arranged to form a coaxial feed with a coaxial ground plane perpendicular to said first and said second sides.
17. The method of claim 13, wherein said attachment is by soldering or by electrically conductive epoxy.
18. The method of claim 13, further comprising applying a conformal coating around said metallic rectangular solid structure enclosing said electronic device and contacting said printed circuit board on at least two sides of said metallic rectangular solid structure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
(1) This application is a continuation-in-part application of currently pending U.S. patent application Ser. No. 17/072,871 filed Oct. 16, 2020 which claims the benefit of U.S. Ser. No. 62/916,941, filed on Oct. 18, 2019, wherein all these applications are incorporated in their entirety by reference.
FIELD OF THE INVENTION
(1) The present invention relates generally to surface mount electronic devices, and in particular, to low temperature co-fired ceramic (LTCC) surface-mounted devices.
BACKGROUND OF THE INVENTION
(2) Isolation of radiofrequency, microwave, millimeter-wave signals and the like from the input port to the output port of a surface-mount LTCC device is important to useful operation of the device and should be maximized. There remains a need for a device and technique to improve this signal isolation.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
(2) FIG. 1 depicts an exemplary diagram according to embodiments of the invention;
(3) FIG. 2 depicts an exemplary diagram according to embodiments of the invention;
(4) FIG. 3 depicts an exemplary diagram according to embodiments of the invention;
(5) FIG. 4 depicts an exemplary diagram according to embodiments of the invention;
(6) FIG. 5 depicts an exemplary diagram according to embodiments of the invention;
(7) FIG. 6 depicts an exemplary diagram according to embodiments of the invention;
(8) FIG. 7 depicts an exemplary diagram according to embodiments of the invention;
(9) FIG. 8 depicts an exemplary diagram according to embodiments of the invention;
(10) FIG. 9 depicts an exemplary diagram according to embodiments of the invention;
(11) FIG. 10 depicts an exemplary diagram according to embodiments of the invention;
(12) FIG. 11 depicts an exemplary diagram according to embodiments of the invention;
(13) FIG. 12 depicts an exemplary diagram according to embodiments of the invention;
(14) FIG. 13 depicts an exemplary diagram according to embodiments of the invention;
(15) FIG. 14 depicts an exemplary diagram according to embodiments of the invention;
(16) FIG. 15 depicts an exemplary diagram according to embodiments of the invention;
(17) FIGS. 16a and 16b depict[s] an exemplary diagram according to embodiments of the invention;
(18) FIG. 17 depicts an exemplary diagram according to embodiments of the invention;
(19) FIG. 18 depicts an exemplary diagram according to embodiments of the invention;
(20) FIG. 19 depicts an exemplary diagram according to embodiments of the invention;
(21) FIG. 20 depicts an exemplary diagram according to embodiments of the invention;
(22) FIG. 21 depicts an exemplary diagram according to embodiments of the invention;
(23) FIG. 22 depicts an exemplary diagram according to embodiments of the invention;
(24) FIG. 23 depicts an exemplary diagram according to embodiments of the invention;
(25) FIG. 24 depicts an exemplary method according to embodiments of the invention;
(26) FIG. 25 depicts an exemplary diagram according to embodiments of the invention;
(27) FIG. 26 depicts an exemplary diagram according to embodiments of the invention;
(28) FIG. 27 depicts an exemplary diagram according to embodiments of the invention;
(29) FIG. 28 depicts an exemplary diagram according to embodiments of the invention;
(30) FIG. 29 depicts an exemplary diagram according to embodiments of the invention;
(31) FIG. 30 depicts an exemplary diagram according to embodiments of the invention;
(32) FIG. 31 depicts an exemplary diagram according to embodiments of the invention;
(33) FIG. 32 depicts an exemplary diagram according to embodiments of the invention;
(34) FIG. 33 depicts an exemplary diagram according to embodiments of the invention;
(35) FIG. 34 depicts an exemplary diagram according to embodiments of the invention;
(36) FIG. 35 depicts an exemplary diagram according to embodiments of the invention;
(37) FIGS. 36A, 36B and 36C depict top, bottom and side views on an exemplary diagram according to an embodiment of the invention;
(38) FIG. 37 depicts an exemplary method according to embodiments of the invention.
(39) Embodiments of the invention are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals indicate corresponding, analogous or similar elements. It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.
DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION
(40) In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.
(41) Embodiments of the invention may be used in a variety of applications. Some embodiments of the invention may be used in conjunction with various devices and systems, for example, low temperature co-fired ceramic (LTCC) devices, printed circuit board (PCB) manufacturing processes such as those for electronic circuits, electronic circuits, and electronic systems. Other embodiments may be used with substrates and substrate materials, lumped element electronic parts, distributed electronic parts and structures and other electronics manufacturing materials, for example epoxies, solders and other attachment materials.
(42) Low-Temperature Co-Fired Ceramic (LTCC) may refer to materials and/or manufacturing processes by which electronic devices, including but not limited to, filters, couplers, transformers, and/or carrier boards, for example, for multi-component assemblies, may be constructed from sheets, e.g. tapes, tape layers, etc., of ceramic material that may feature, for example, embedded metallic vias and/or printed metallic conductors, which may be collated, singulated, and/or sintered, e.g. co-fired, into, for example, monolithic devices. Such devices may be devices constructed using such processes.
(43) An embodiment of the invention may be comprised of a shielding structure surrounding a circuit, or one or more circuit elements or parts, constructed on, or part of, an LTCC substrate. The shielding structure may be external and/or may surround the circuit within and may be constructed of metal, or metal plated supporting material and may have a continuous metallic circumference. A shielding structure may have a solid envelope shape, rectangular in nature, or any other suitable geometric shape. The metal may be continuous around an entire device, in three dimensions, with the exception of metallic relief where electronic signals, e.g. baseband, radio frequency (RF), microwave or millimeter-wave signals, may transition into and/or out of an enclosed circuit. In some embodiments the metallic shield may not be continuous and may have discontinuities, apertures, etc. as may be necessary for certain electrical structures, manufacturing processes or other mechanical or process reasons. In some embodiments where there may be such physical discontinuities there may be electrical continuity at frequencies above zero hertz (Hz), for example by electrical signal coupling, capacitive coupling, electromagnetic field coupling, and the like.
(44) A shielding structure may be manufactured or assembled coherently with an enclosed LTCC circuit and/or component. Alternately, a shielding structure may be added following manufacture of an LTCC circuit and/or component. A shielding structure may be added prior to or during a PCB assembly process.
(45) An LTCC circuit and/or component enclosed by a shielding structure may have a grounding structure that may be compatible with a shielding enclosure. Grounding may be direct current (DC) electrical grounding or may be by electromagnetic grounding, e.g. as with a Faraday enclosure effect. A shielding structure attached to an enclosed LTCC circuit, LTCC structure and/or device may form an electromagnetic shielding enclosure or other electrical grounding. A grounded shielding structure may be self-contained or may be attached to a circuit ground on a PCB. A shielding structure that may be electrically and/or mechanically connected to a circuit ground on a PCB may electrically share the same electrical ground properties of the circuit on the PCB. An LTCC component may have features of a grounding structure that may be compatible with an external shielding.
(46) A shielding structure may have elements and/or design features that when assembled in conjunction with or onto, a PCB, may facilitate a self-alignment onto the PCB. An LTCC circuit and/or device may have elements and/or design features that when assembled in conjunction with, or onto, a PCB, may facilitate a self-alignment onto the PCB. Such self-alignment may occur during reflow solder assembly or another assembly process.
(47) A shielding structure may, when electrically and/or mechanically attached to an enclosed LTCC circuit and/or device, improve the suppression of unwanted, undesired, or otherwise out of band electrical signals that may be transitioning the device. In an exemplary embodiment of a filter device, e.g. an LTCC based filter, rejection of signals that may be considered to be in a stopband frequency bandwidth may be increased and/or improved. For example, the addition and/or use of a shielding enclosure improves a stopband rejection of a surface-mount filter, and such a filter may be constructed using one or more LTCC circuits and/or devices. A passband frequency bandwidth of such a device may be preserved, or experience no or minimal degradation, as compared to a device without such a shielded enclosure. Use of such a shielded enclosure may produce no other ill or degrading effects, or perceptible ill effects, on the signal desired to transition the device, e.g. an electrical signal in the passband.
(48) An exemplary embodiment may be a three-dimensional rectangularly shaped electrically conductive shielding structure encircling an LTCC filter, such electrically conductive shielding structure operably connected to the signal ground of the filter to form part of the filter grounding circuit. Such an electrically conductive shielding structure may be formed as part of an LTCC filter, or alternately may be formed separately and be operably attached to an LTCC filter. Another exemplary embodiment may be an electrically conductive shielding structure formed separately and operably attached to an LTCC filter, where such electrically conductive shielding structure encircles on three sides, and may be attached to a PCB with a ground plane, and the PCB ground plane may form a fourth side together with the electrically conductive shielding structure to provide encapsulation. In some exemplary embodiments a fourth side in a plane parallel to the third side may be operably, electrically and/or mechanically attached to the first and second sides, and may be designed to and/or constructed to operably, electrically and/or mechanically attach to a ground plane on a PCB.
(49) In an exemplary embodiment an electrically conductive shielding structure may be three-dimensional rectangular in form and/or structure, and have at least three electrically conductive sides, each external and around an LTCC circuit, e.g., an LTCC filter. Two such sides may be in planes parallel to each other and a third side may be between the other two sides and be in a plane perpendicular to such parallel sides. Such a third side may be in a plane parallel to a PCB onto which an electrically conductive shielding structure and an associated LTCC circuit, e.g., an LTCC filter, may be operably, electrically and/or mechanically attached. Other exemplary embodiments may include an electrically conductive shielding structure that may be on a fifth and/or a sixth side, operably, electrically and/or mechanically connected to an electrically conductive shielding structure on the first, second, third and fourth sides, such fifth and sixth sides each located in a plane parallel to each other, and such parallel planes perpendicular to the planes of both the first and second sides and parallel to the planes of the third and fourth sides.
(50) Exemplary embodiments may have one or more apertures within each of two or more sides to allow for passage of electrical signal energy between an interior and an exterior of an electrically conductive shielding structure without making electrical contact to the electrically conductive shielding structure. An aperture may include an electrically conductive wire, transmission line, lead etc., at one end operably connected to a circuit, e.g., an LTCC circuit, within an electrically conductive shielding structure, and an opposing end to be connected to an external electrical circuit, e.g., a circuit on a PCB, such an opposing end may be, for example a pad, port, or other designation. Such an electrically conductive wire, transmission line, lead, etc., may be mechanically attached to an insulator material, such insulator material electrically isolating it from a surrounding electrically conductive shielding structure, and mechanically attaching it to such electrically conductive shielding structure. An insulator material may be a polymer, a plastic, a dielectric material, e.g., polytetrafluoroethylene (PTFE), glass, or any other suitable insulator material. An insulator material may be mechanically attached to form a hermetic seal, and an enclosed circuit, e.g. an LTCC circuit, may be, for example, hermetically sealed within an electrically conductive shielding structure.
(51) An exemplary embodiment may have one or more sides, e.g., external face of sides, of an electrically conductive shielding structure that may be smooth and/or fully or substantially within a single plane corresponding to each single side. Another exemplary embodiment may have one or more sides, e.g., external face of sides, of an electrically conductive shielding structure that may be smooth and may have a convex shape, e.g., a bulge, outward from the electrically conductive shielding structure, for example as may be associated with an epoxy fillet or conductive epoxy fillet.
(52) A shielding structure may be designed for manufacturability. It may have features of one or more units that may be milled into a single workpiece and may prevent a necessity of re-orienting such a workpiece within a construction device, e.g. a mill or milling machine. One or more devices may be removed or separated from a workpiece, for example by a cutting or dicing process. Individual devices that may be separated from a workpiece may undergo one or more finishing processes.
(53) According to embodiments of the invention, a shielding structure may have one or more features. Such features may be milled into a material during the manufacture of a shielding structure and may have a common orientation. A common orientation of such milled features may permit machining, or modification by manual, automated, computer numerical controlled (CNC) machine, or by another machine type, to be performed without a need or a necessity to re-orient the position of a workpiece, for example with respect to a machine. An orientation may remain steady or constant during such machining or manufacturing process. Other manufacturing processes, e.g. dicing or deburring, may occur with the part oriented differently, according to each different process.
(54) There may be cavities, or regions of relief or removal of material, above a component, e.g. an LTCC component and/or its signal terminals. Such cavities may have an effect of reducing parasitic capacitance or other undesired effects. Parasitic capacitance may refer to an undesired and/or unavoidable electrical capacitive effect between conductive portions of a circuit which may cause a circuit to exhibit an electrical impedance different from its desired and/or design value. Inclusion of one or more such cavities may allow a shielding structure to be used, connected or implemented, and will not cause any noticeable or relevant degradation or reduction in a desired electrical performance of a device or circuit. Cavities referred to as being positioned, for example, above a component, e.g. an LTCC component and/or its signal terminals, may, for example, refer to a position on an opposite side of a component circuit may be mounted to a PCB, where such a PCB may be referred to as, for example, being below a component.
(55) A cavity may be milled into a workpiece during a manufacturing process of a shielding structure and may be milled in any direction, according to the manufacturing process. For example, a cavity may be milled down from a higher to a lower vertical position. In an exemplary embodiment, a workpiece that may be manufactured into a shielding structure may then be installed in an inverted configuration, for example relative to the direction of milling and/or manufacture, and such a cavity may then be positioned vertically above a component or circuit, e.g. an LTCC device. Following installation or attachment of a shielding structure to a device or circuit, e.g. an LTCC device, LTCC circuit, etc., an assembled piece, that may include both a device or a circuit and a shielding structure, may be oriented in any direction or orientation. Such orientation or direction may be according to a desired electrical performance, compatibility with another manufacturing process, e.g. attachment to a PCB by solder, solder reflow, epoxy, etc., or any other purpose that may allow a use of the assembled device.
(56) Embodiments of the invention may include one or more design elements to increase an ease of manufacturing, assembly, etc. There may be a grounding structure that may wrap around, for example, an LTCC component. A structure with such a wrap-around ground element may facilitate attachment of a shield, or shielding structure, to a PCB or other supportive structure with a mechanical attachment process, for example a solder reflow process. A wrap around grounding structure may be continuously electrically conductive and/or operably continuously electrically conductive, for example creating a Faraday encapsulation effect, capacitively coupling electrical encapsulation, or any other electrical encapsulation operative at least across one or more operational frequency bands.
(57) A shielding structure may include a solder cup, or other relief in the material, for example, to capture solder or other attachment materials. A solder cup may facilitate assembly and may be used for precision control of alignment and/or precise dimensional control of an assembly process. Precise control may be necessary, for example to prevent a solder fillet from becoming too thick, which may cause a shield to sit too high on top of a surface-mount component, and may cause difficulty or prevent electrical and/or mechanical attachments, e.g. legs, from contacting metallization on a PCB. Electrical contact to a PCB metal is desired to transfer electrical signals between a PCB circuit and a component, e.g. an LTCC device. Mechanical contact and/or a mechanical connection, e.g. a solder attachment, may be used for mounting such a component, e.g. an LTCC device, with continuous electrical contact to a PCB and PCB circuit. A solder cup may be used to maintain a minimum thickness of a solder fillet. In some exemplary embodiments, a flat surface, for example, in place of a solder cup may present a difficulty in maintaining a minimally thick solder fillet. Excess solder may remain within a solder cup, or may be wicked into a solder cup, e.g. by capillary action, or other movement processes, and may occur when such solder may be in a molten state. Solder that may be placed into a solder cup may be in a paste or any other suitable form. Such solder may be used for attachment of a shield to a device, e.g. an LTCC device. A solder cup may be used to control and/or predetermine an amount of solder to be used during an assembly or attachment process. A solder cup may be a predetermined size, or with a predetermined interior volume, that may correspond to a predetermined amount of solder to be used in an associated assembly or attachment process.
(58) A solder cup may be used with solder in any form, for example solder wire, solder paste, solder bar, etc., and may be with or without flux that may be for improved solder adhesion. Solder or solder paste may, for example, compensate for a variation that may be in one or more gaps at points of contact. Solder or solder paste may provide a self-centering and/or an alignment aide function. Solder or solder paste may have low resistivity properties that may produce low resistivity connections. Solder or solder paste may be used to attach a shield to a PCB. In some embodiments different solder, solder types and/or other attachment methods may be used to attach different elements of embodiments of the invention alone or in combination.
(59) In some exemplary embodiments, a shielding structure may be mechanically attached by an intermediary element, for example, a conductive elastomer, a mesh film, e.g., an Indium mesh film, or any other suitable electrically conductive mechanical intermediary attachment element. Such an element may provide compensation for mechanical voids or gaps, for example that may arise from surfaces that may not be fully flat or fully smooth. Such an element may aide in visual alignment, either manually or mechanically. Such an element may provide a low resistivity contact among element being attached. Such an element may provide for attachment and/or securing to a PCB. One or more such elements may be used alone or together. Other mechanical attachment devices and/or techniques may be used, for example an attachment where a partially flexible attachment tab on a shield may be inserted into a corresponding aligned hole on a PCB, e.g., a “snap-in” attachment, alignment pin, etc.
(60) A shielding structure may be internal, for example, internal to an LTCC device, e.g. an LTCC filter device. Such an internal shielding structure may be within a surface mount technology (SMT) device, for example a surface mount LTCC filter. An internal shielding structure may increase rejection of undesired signals, e.g. RF power signals, impinging at a predetermined frequency band for rejection by a filter, e.g. a filter constructed in a surface mount device. Such an internal shielding structure may improve the stopband rejection of a filter, e.g. a surface mount filter. An internal shielding structure may be designed and constructed to not interfere with a passband performance of a filter while providing an increase in stopband rejection. An internal shielding structure may be designed and constructed to either act independently or in conjunction with an external shielding structure, for example by interfacing with an external shielding structure. A rejection of signals may be a prevention of signals from transiting, for example, from an input to an output of a device or circuit. A filter may be an electrical circuit designed to allow transiting of a predetermined frequency band of electrical signals while simultaneously preventing transiting of one or more other predetermined bands of electrical signals, for example, from an input to an output of a device or circuit. A filter may be referred to as a frequency selective electrical circuit.
(61) An LTCC device may possess or include metallization on its top and/or sides, constituting a package with built-in electromagnetic shielding. Such a shielded package may have metallization printed, sputtered, or otherwise applied to one or more surfaces, e.g. faces, and may provide shielding to prevent RF signal leakage, for example leakage and/or transmission of electrical signal energy between an interior and an exterior of such shielded package. A shield metallization of such a package may make electrical contact with a ground plane of a carrier PCB, onto which it may be mounted, or other structure. A thickness of a shield metallization may be, for example, a minimum thickness to prevent electrical and/or RF signal leakage, and may include a minimum thickness sufficient for a skin depth of an electrical and/or RF signal. A thickness may be a minimum design thickness, a predetermined thickness or may be greater than, for example, a predetermined minimum thickness. A shield metallization of such a package may have openings surrounding signal pads, or ports. Signal pads may be surrounded by shield metallization openings that may permit transmission of electrical signals, for example, into and/or out of a device, package, etc., through, for example, a coaxial transmission line, TEM transmission line, or other structure.
(62) An interface between an internal shielding structure and an external shielding structure may be by a direct electrical connection, an RF energy coupled connection, or any other connection method to provide an interface for continuity of shielding of RF signal energy. An LTCC device may contain an internal grounding structure, for example, a grounding cage which may act in a manner according to a Faraday cage, or according to other similar electromagnetic principles, and may provide an internal RF signal power circuit ground. Such a device may be operably and/or electrically connected to external terminal, for example for an external connection to RF signal power grounding elements of an external electronic circuit, e.g. an external circuit on a PCB.
(63) An interface may have design elements and/or features to facilitate operation together between an external shielding structure and an internal shielding structure. Design elements may be geometric features, individual electronic circuit elements, e.g. lumped elements, for example, resistors, capacitors, inductors, etc., distributed circuit elements, e.g. transmission lines, coupling structures, etc., or any combination thereof. Design elements may be part of an internal shielding structure, and external shielding structure, or both structures. Design elements may be separate to a device, a circuit device or circuit element, e.g. an LTCC device, an LTCC filter device, etc., or may be integrated within a device or element. An internal shielding structure and an external shielding structure may be constructed to use a common circuit ground element, a common external grounding structure, and/or any other circuit grounding structure or mechanism.
(64) An internal shielding structure may be constructed using one or more fabrication processes. A fabrication process may be an LTCC fabrication process, another fabrication process, or a combination of an LTCC fabrication process and one or more other fabrication processes. An internal shielding structure may be constructed to be used with a device that may be mounted into a quasi-transverse electromagnetic (TEM) circuit, e.g. a microstrip electronic circuit, a full TEM circuit, e.g. a stripline electronic circuit, or other electronic circuits or electronic structures. An internal shielding structure may be constructed to be used with a coplanar waveguide electronic circuit and may be in a microstrip configuration, a stripline configuration, or another coplanar waveguide or other waveguide configuration. Such a shielding structure may include features and/or elements, for example tabs, pins, protrusions, coupling elements, etc., to interface with a circuit, e.g. a microstrip circuit, a stripline circuit, etc. An LTCC device may be constructed with one or more internal shielding structures, and each may be operably and/or electrically connected to an external shielding structure, either by an independent connection or by a shared connection. An internal shielding structure may be integrated into an LTCC device or circuit, located around, either partially or fully, e.g. fully encapsulating except for active circuit transmission conductors, an LTCC device or circuit, or may be around one or more parts of an LTCC circuit device. An internal shielding structure may be constructed to be within an exterior package of an LTCC device.
(65) A device, for example, an LTCC device, or a circuit within an LTCC device or package, may be constructed with an internal shielding structure. An internal shielding structure may be connected to an external shielding structure. An external shielding structure may be continuous around a plurality of sides, e.g. four sides, six sides, etc., of a rectangular solid structure for containing or housing an RF circuit, including RF circuit parts and/or elements. A shielding structure may be constructed, for example of a metal electrical conductor, and may be a shielding conductor. A shielding structure may be on and/or continuous with a surface to be attached to a printed circuit board (PCB). A surface for attachment to a PCB may have a shielding conductor covering all or part of such a surface. A part of such an attachment surface may have one or more conductors that may be electrically connected to circuit elements that may form an electrical circuit and/or structure, e.g. a filter circuit, that may have a conduction path electrically isolated from a shielding structure, and such conductors may be electrically isolated from a shielding structure. Electrical isolation may be by physical separation of conductors on a surface, and such a separation may be large enough to prevent electrical signal coupling from occurring across the separation. A range of separation distances may construct, for example a separation distance may be equivalent to a dimension of a conductor electrically connected to an input or an output of a filter circuit. Or a separation distance may be larger than a dimension of a conductor electrically connected to an input or an output of a filter circuit, for example two times larger or three times larger, or any other suitable separation distance. A conductor electrically connected to an input or an output of a circuit, e.g. filter circuit, may be encircled by a shielding structure or may extend to the edge of a surface. A conductor electrically isolated from a shielding structure may be formed together with a shielding structure and an electrically isolating insulator, or a predetermined separation distance, or both, to form a transmission line or transmission line structure, e.g., a TEM transmission line or a quasi-TEM transmission line.
(66) A shielding structure may be constructed such that it employs one or more full tape thickness features. Such full tape thickness features may provide improved and/or optimal electrical grounding for ground connections of a circuit, e.g. an LTCC filter circuit, or of a shielding structure, e.g. an internal or an external shielding structure of an LTCC circuit. A full tape thickness feature may refer to a conductive trace embedded within a dielectric layer of an LTCC, and may be an alternate to such printed upon it. Such full tape thickness features may provide improved and/or higher isolation of RF signals from external interference and/or coupling. Other than full tape thickness may be used, and may have corresponding RF signal isolation performance.
(67) A printed circuit board (PCB) may be used to accept mechanical mounting and/or electrical connection of devices, e.g. LTCC devices, according to embodiments of the invention. Such LTCC devices may be mechanically and/or electrically attached to such a PCB. Such a PCB may have sections of its ground plane in the area of attachment where metallization may have been removed, for example, a ground plane cut-out. Such a cut-out may be used to constrain a position of electrical connection leads of a device, for example an LTCC filter, during a manufacturing process. An exemplary manufacturing process may be reflow soldering. Other suitable manufacturing processes for attachment of the device to the PCB may also be used. Such electrical connection leads, e.g. legs, may be metalized connections that transition from, the interior to the exterior of a shielded device, and may electrically or operably connect to input and/or output ports of an enclosed device, e.g. an LTCC filter. Such leads may extend through an aperture in the shielded enclosure and may be electrically isolated from such a metallic shielded enclosure. An end of such leads that may facilitate attachment external to a shield may be used to attach the shielded component assembly to a PCB, for example by a surface-mount attachment process.
(68) Such a PCB may be manufactured to have thin traces or electrical conductor connections. Such traces may be considered thin with respect to electrical conductors on the same PCB that may have larger widths in order to maintain a specific characteristic electrical impedance or a predetermined electrical impedance. Thin traces may provide additional surface tension, which may prevent solder outflow without the use of a solder mask, among other benefits. Solder outflow may occur, for example when solder may be in a molten state. Solder may be a paste, a wire, a sheet, or any other suitable structure compatible with solder attachment manufacturing. In some exemplary embodiments attachment mechanisms other than solder, or in combination with solder, may be used.
(69) In some embodiments, an electrical impedance may be an electrical signal resistance of alternating current (AC) signals and their associated electrical signal energies transitioning an electrical conductor. An impedance may be a complex ratio of voltage to current, e.g. AC voltage and AC current. Electrical impedance across a transition among electrical conductors, electrical devices, electrical circuits and/or combinations of the like, may be constant when an electrical impedance of each conductor, device, circuit and/or combination may be substantially the same. When an electrical impedance differs, a mismatch may be created. Such a mismatch may have a characteristic of an increase in reflected electrical energy. Such a mismatch may be characterized by a reduction in electrical energy being delivered into or out of a conductor, device, circuit and/or combination.
(70) Electrical impedance may vary with varying frequencies of AC signals and may be considered to be frequency-dependent devices. Devices for selecting specific frequencies of electrical energy, e.g. baseband signals, passband signals, radio frequency (RF) signals, microwave signals, millimeter-wave signals, etc., for transition through one or more conductors, devices, circuits and/or combinations while rejecting other specific frequencies of electrical energy may be considered to be and/or referred to as filters. Filters may be constructed using low temperature co-fired ceramic (LTCC) materials and/or processes and may be LTCC filters. LTCC filters may be individual devices or part of an electrical circuit.
(71) A PCB may have other features, for example, a stepped leg cross-section. A stepped cross-section, as depicted by figures herein, may refer to a stepped decrease in cross-sectional area of a mounting leg of, for example, a filter that may be adjacent to its contact area upon a PCB. A stepped leg cross-section may be used to reduce an amount of solder needed to mount a shield, according to embodiments of the invention. Use of such a stepped leg cross-section may reduce a tendency of a shield to reposition, or “float,” during a manufacturing process, e.g. reflow soldering. A number of steps of a stepped leg cross-section may be predetermined.
(72) FIG. 1 depicts an exemplary embodiment of the invention. A shielded LTCC filter device 100 may be a metallic shield enclosure 150 or may be an enclosure made of another material, e.g. plastic, and may surround and/or encapsulate a device, e.g. an LTCC electrical AC filter circuit. A shield may have vertical metallic lined holes or solid metallic filled holes, e.g., via holes, components 110, and/or other vertical metallic shielding walls 140. Via holes may be electrically connected to one or more circuit elements at either or both ends of such a via hole, e.g., a transmission line. A shield may be attached to a PCB 170 with ground 120. An LTCC filter may have input and output connection leads 130 that may be connected to a transmission line and/or other electrical circuits and/or devices on PCB 170 and/or on other PCBs. A shielded LTCC filter device 100 may have a marking 160 on its outer surface, opposite a PCB 170 mounting surface, that may indicate a function of one or more lead connections, e.g. a marking 160 may be located near a particular LTCC circuit lead connection to indicate a location of pin 1, or an input pin. A marking may be used for orientation of a device when attaching it, for example, to a PCB. A size of a shielded LTCC filter device 100 may be depicted with a linear unit scale 180, e.g. millimeters, to indicate a small size of such a device. A feature and/or benefit of embodiments of the invention may be achieving such shielding effectiveness within a total package envelope of such a small size, as depicted by exemplary FIG. 1. Construction according to embodiments of the invention may achieve this performance result within such a small envelope.
(73) FIG. 2 depicts an exemplary embodiment of the invention. A shielded LTCC filter device 200 may be fully encapsulated by, for example, a ceramic package, excepting only input connection 220, output connection 230 and ground metallic connections. A metallic shield 210 may wrap around an entire circumference of such a solid rectangular package, and may be constructed for connection to an external ground, e.g. a PCB ground. Input connection 220 and/or output connection 230 may be constructed with a planar protrusion in the plane of the mounting surface, an “L” shaped protrusion with one surface co-planar with the mounting surface and a second extending surface extending vertically perpendicularly away from the mounting surface, or a “U” shaped protrusion with one surface co-planar with the mounting surface, a second extending surface extending vertically perpendicularly away from the mounting surface and a third surface extending from the vertical surface partially around the circumference of the device parallel to the mounting surface.
(74) FIG. 3 depicts an exemplary embodiment of the invention. A shield 300 formed with a flat coplanar surface 330 may encapsulate a device, e.g., an LTCC device or filter circuit, and may fully surround such device continuously across all six sides. Two or more second apertures 340 are provided having relief of the continuous metal on the coplanar surface side extending from the interior to the exterior of a metallic outer surface. Only an electrical connection terminal for an input 310 and an electrical connection terminal for an output 320 may protrude from an interior of such a shield to an exterior of such a shield. Each of input lead 310 and output lead 320 may be separated from ground shield 300 by a planar relief area around each terminal lead 310, 320, larger than a terminal, with no metal or electrically conductive material, such that there may be no electrical connection between either of these leads and a ground shield 300. Such a relief area may reside in the same plane as terminals 310, 320. In such an exemplary embodiment, a shield 300 may encircle such a relief area, itself encircling a terminal 310, 320, all in the same plane. Terminals 310, 320 also represent additional examples of one or more geometric features of the metallic outer surface for attachment to metallic elements on a printed circuit board. When configured accordingly, such a device enclosed by shield 300 may be constructed to be compatible with a particular type of electrical circuit PCB, e.g., a stripline circuit.
(75) FIG. 4 depicts an exemplary embodiment of the invention. A device may be as in an embodiment depicted by FIG. 3, and may be observed from an alternate view, or an opposing view, depicted by FIG. 4, showing shield 400 fully encircling such a device, e.g. an LTCC filter electrical circuit, an RF circuit, etc. A marking 410 may be inscribed, printed, plated, or otherwise attached closer to an edge of shield 400 in a plane parallel to a mounting surface, and such plane residing on an opposing side to such mounting surface, e.g. in a solid rectangular package. Marking 410 may be used to indicate a function of a terminal or lead, e.g. a lead used as an input to an LTCC electrical circuit, an indication of guidance for orientation during attachment, or any other suitable function.
(76) FIG. 5 depicts an exemplary embodiment of the invention. A shielded LTCC filter device 500 formed with a flat coplanar surface 570 may be surrounded by a metallic shield enclosure 520 or may be an enclosure made of another material, e.g., plastic, and may surround and/or encapsulate a device, e.g., an LTCC electrical AC filter circuit, and may provide electrical circuit grounding. A shield may have vertical metallic via holes components 510, and/or other vertical metallic shielding walls or alternate internal shielding components. Vertical metallic via holes may be arranged to be operable as an electrical wall, for example an electrical shielding wall, where a distance between successive vertical holes may be reduced to prevent RF electrical signal leakage. An internal shield may include horizontal shielding elements 560, e.g., plates, walls, etc., and may be conductive and/or attached to a device circuit ground. Two or more second apertures 580 can be provided having relief of a continuous metal on the coplanar surface side extending from the interior to the exterior of a metallic outer surface. A shield may be attached to a PCB with ground plane 530. An LTCC filter may have input and output connection leads 540 that may be connected to a transmission line and/or other electrical circuits and/or devices on a PCB. Each of input and output leads 540 may be separated from ground shield 530 by a planar relief area 550 around each terminal lead 540, larger than a terminal 540, with no metal or electrically conductive material, such that there may be no electrical connection between either of these leads 540 and a ground shield 550. Such a relief area may reside in the same plane as a terminal 540. The leads 540 also represent one or more geometric features of the metallic outer surface for attachment to metallic elements on a printed circuit board.
(77) Referring to an exemplary embodiment depicted by FIG. 6, a device 600, e.g. an LTCC electrical RF filter circuit component, may be assembled or attached onto PCB 620. An input electrical lead connection may be made by attaching input lead 640 to for example, an RF transmission line on PCB 620. An output lead 610 may be similarly attached and/or electrically operably connected, for example to another transmission line on PCB 620. A shield may be constructed around LTCC filter device 600 and may be attached to PCB ground 630.
(78) FIG. 7 depicts an exemplary embodiment of the invention. According to an embodiment of the invention, a metallic shield 700, e.g. a shield for enhanced RF electrical isolation of an enclosed LTCC frequency selective filter, may be constructed. Such a shield may have a solder cup 710 feature for ease of construction and/or attachment using solder, or for facilitating use of a predetermined amount of solder. One or more cavities 730 may be constructed, e.g. metallic shield material may be removed, milled away, etc., to form a cavity, such that cavities 730 may be located vertically above, or partially around, one or more filter circuit elements, or other electrical transmission lines, components, etc., when mounted and/or attached to such enclosed electrical circuit. A shield element may be comprised of one or more stepped shield legs 720, as part of such a shield, and may be, for example, for attachment to a PCB ground plane. In some embodiments, shield 700 may be manufactured in a same work part as other such shields, and may have a common orientation of features 740, e.g. milled features, among all such work parts. Vertically above may refer to a position relative to a component, for example an enclosed LTCC circuit, when such component is mounted to a PCB and such PCB is referred to as below a component. Metallic shield 700 may be a single metallic element, or may be comprised of two or more metallic elements or metallic plated elements, each electrically, mechanically and/or operably connected.
(79) FIG. 8 depicts an exemplary embodiment of the invention. A shield 800 may be as in an embodiment depicted by FIG. 7, and may be observed from an alternate view, as depicted in FIG. 8. Such a view of shield 800 may depict soler cup 810 as an exemplary embodiment where it may be a circular, or concentric cylindrical, solid feature. A solder cup may be any other suitable three-dimensional solid geometric shape, and may have at least one open side.
(80) FIG. 9 depicts an exemplary embodiment of the invention. A shielded LTCC RF filter component 900 may be attached to a PCB 930. An input connection 920 and an output connection 920 may be made between LTCC filter 900 and two or more, e.g. at least one input and one output, transmission lines on PCB 930. A shield of LTCC filter component and/or device 900 may be attached to a ground 910 on PCB 930.
(81) FIG. 10 depicts an exemplary embodiment of the invention. A component 1020, e.g., an LTCC RF filter component, may be surrounded by a shield 1000, and may be attached to a PCB 1010. Shield 1000 may be attached to LTCC filter 1020 prior to attachment to PCB 1010, during such attachment process, or after attachment of LTCC device 1020. According to embodiments of the invention, shield 1000 may operate in a same manner independent of when it may become surrounding of LTCC component 1020, with respect to an order of attachment to PCB 1010. Shield 1000 is depicted with a first and a second side parallel to each other and each perpendicular to the plane of the PCB, each comprising solid electrically conductive material. Third and fourth sides are parallel to each other and are each mutually perpendicular to the plane of the PCB and the plane of the first and second sides, where the third and fourth sides each have an aperture allowing transfer of an electrical signal between an interior and an exterior of shield 1000. An aperture may comprise an air insulator, a ceramic insulator, a polymer insulator, a glass insulator, any other suitable insulator, or a combination of two or more insulators. For example, an aperture in shield 1000 is depicted as a combination of an air insulator and a ceramic insulator, where a ceramic may be part of component 1020. An insulator may also include a separation on a PCB of a signal conductor, e.g., a circuit trace, and a ground plane on a PCB. An aperture may be designed and/or constructed as a transmission line, e.g., a TEM transmission line, and may have predetermined dimensions and/or predetermined distances between conductive lines and ground planes. An aperture may alternately be a position where electrical signals may be conducted between an interior and an exterior of shield 1000 with one or more insulators, air gap, etc. between a signal conductor and a ground plane and/or shield 1000.
(82) FIG. 11 depicts an exemplary embodiment of the invention. Shield 1100 may be comprised of a homogeneous material, or of two or more materials 1110 fused or otherwise attached or combined together, or of two or more layers of a same material, or any combination thereof, to form such a shield 1100. Shield 1100 may depict a shield internal to a device or external to a device. Two or more materials 1110 may be depicted within a cut-away view 1110, to better depict materials below a top material. Such a cut-away view or combination or combinations of layers is not meant to restrict a size of any one material or layer with respect any other.
(83) FIG. 12 depicts an exemplary embodiment of the invention. A component 1210, e.g., an LTCC RF filter component, may be surrounded by a shield 1200. Shield 1200 may be attached to LTCC filter device 1210 before, during or after attachment to, for example, a PCB. A combination of component 1210 and shield 1200 may be suitable for assembly or construction onto a PCB or other circuit.
(84) FIG. 13 depicts an exemplary embodiment of the invention. An LTCC RF filter component 1310 may be surrounded by a shield 1300 and may be attached to a PCB 1320. Attachment may be made at a circuit input connection, or lead, an output lead and/or at a ground connection. A ground connection may be between shield 1300 and electrical ground features of PCB 1320. Electrical ground features of PCB 1320 may be a ground plane, ground and/or attachment pins, leads or tabs, other attachment features, or any combination of such features. PCB 1320 may have a continuous ground plane, a ground plane with via holes, and/or other ground features.
(85) FIG. 14 depicts an exemplary embodiment of the invention. An isometric view of a device 1410, e.g., an LTCC device, with an external shield 1400 is shown, with elements of FIG. 14 shown with transparency for visual clarity of the figure. Internal and external grounding structures, as depicted by other figures, may be visible in such an exemplary embodiment. Grounding from shield 1400 to a PCB may be by attachment to a ground connection 1420 on PCB 1430.
(86) FIG. 15 depicts an exemplary embodiment of the invention. A side view of a device, e.g., an LTCC device, surrounded by a shield 1500 is depicted. An internal grounding structure, e.g. a grounding cage, may be comprised of horizontal shielding elements 1510, vertical shielding elements 1520, or a combination of one or more of each such elements. Shielding elements 1510, 1520 may be solid structures, via holes, or any combination of such elements. A shield may be attached to a PCB ground at 1530. A PCB ground attachment 1530 may be referred to as being below, or vertically below, a device, for example for purposes of relative description of orientations.
(87) FIGS. 16a and 16b depict views of exemplary embodiments of the invention. A shield 1600 may surround an LTCC device 1610, e.g. an LTCC filter. Such shield 1600 and LTCC filter 1610 may be attached to a PCB 1620. PCB 1620 may be constructed and/or manufactured to support a transmission line, e.g., a stripline, microstrip, etc., electrical RF transmission structure having transmission lines 1630 that may not be exposed outside such a structure. Electrically conductive structures 1640, e.g. metallic vertical vias, may be formed within a top layer of stripline PCB 1620 to facilitate an electrically operable and/or conductive connection between transmission lines 1630, e.g. input and/or output transmission lines, and input and/or output connections, e.g. terminals, leads, ports, etc., of LTCC circuit 1610. Other vias 1640 may be used to electrically operable and/or conductively connect, for example, a top ground plane stripline ground conductor of stripline 1620 to a bottom stripline ground conductor of stripline 1620, and/or to grounding features of a shield of LTCC component 1600.
(88) According to an exemplary embodiment of the invention, an LTCC filter may be constructed and mechanically attached to a PCB, and electrical operable connections may be made to allow measurement of an LTCC filter device. FIG. 17 shows an exemplary electrical performance result of such a measurement, depicting a same result both over a broad frequency range and over a narrow frequency range. Such a narrow frequency range may be a sub-set of a broad frequency range, and may be around and/or encompass, for example, a passband of an LTCC filter device constructed according to embodiments of the invention. A response of RF electrical energy transiting, or passing, through such an LTCC filter is depicted 1700, and may show minimal or no degradation of a passband signal 1700, for example, as a result of implementing and/or attachment of a shield in accordance with embodiments of the invention. A return loss, or reflection response, 1710 is depicted showing reduced reflections within a desired design passband and high reflections throughout a desired design stopband. High reflections may be an indication of a stopband performing as designed and/or as intended, where an increase in reflections in a stopband may be, for example, an indication of an improvement in a functioning of a filter. Such exemplary performance may be from, for example, an LTCC filter with a shield grounded to a stripline PCB, fully enclosing such device excepting only input and output ports, and may have internal vias and/or additional internal grounded shielding structures. Such electrical characteristics may be characterized as a filter with good, or improved, performance. Such a device according to embodiments of the invention represent improvements over other technologies and depicts clear performance advantages.
(89) FIG. 18 depicts an exemplary embodiment of the invention. A shielded case 1800 of a device, e.g. an LTCC filter device, may have ports, or electrical signal launches, 1820 for attachment and use with a co-planar waveguide (CPW) and/or a microstrip PCB. Grounding of such a device 1800 may be by ground attachment 1810, electrically operably connected to a shield of device 1800. An exemplary device as depicted in FIG. 18 may have a shielding structure on four sides, where a fourth side with ground attachment 1810 may have apertures for transfer of electrical signal energy between an interior and an exterior of case 1800 that may be located coplanar with a surface for attachment to a PCB.
(90) FIG. 19 depicts an exemplary embodiment of the invention. A shielded case 1900 of a device, e.g. an LTCC filter device, may have ports, or electrical signal launches, 1920 for attachment and use with a stripline PCB. Grounding of such a device 1900 may be by ground attachment 1910, electrically operably connected to a shield of device 1900. An exemplary device as depicted in FIG. 19 may have a shielding structure on six sides, where a fourth side with ground attachment 1910 may have apertures for transfer of electrical signal energy between an interior and an exterior of case 1900 that may be located coplanar with a surface for attachment to a PCB.
(91) FIG. 20 depicts an exemplary embodiment of the invention. A shield 2000 of a device, e.g. an LTCC filter device 2020, or other circuit 2020, may be used to improve performance of such a filter device, and may be internal, e.g. mechanically embedded within, external, e.g. exposed to an environment around such a device, or a combination of both. A shield may be comprised of horizontal elements 2000, vertical elements 2010, e.g. walls, via holes, etc., or a combination of such elements, and may be electrically conductive, e.g. comprising an electrical signal energy transmission ground or electromagnetic ground or signal ground reference. A shield may be operably and/or electrically connected to a signal ground of a device within such a shield. Such a shield 2000 may be comprised of one or more layers, and such layers may be electrically operably and/or mechanically connected. A ground connection to and/or on a PCB may also be such a layer. For positional reference, horizontal may refer to a plane parallel to a mounting surface plane, or a plane of a top surface of a PCB onto which such an exemplary device may be mounted. Also, for positional reference, vertical may refer to a plane perpendicular to a mounting surface plane, or a plane of a top surface of a PCB onto which such an exemplary device may be mounted. Vertical elements 2010 may be solid rectangular, solid cylindrical, or any other suitable solid geometric shape. Electrical signal energy may flow into and/or out of such an LTCC filter 2020 via one or more electrically operable connections to a PCB 2030, for example, onto which such a circuit 2020 and its associated shield 2000 may be mounted, at input and/or output signal connections, e.g. leads, ports, terminals, etc., and may be through an aperture, for example an aperture in a shield. Electrically conductive layers may be embedded within an LTCC structure or may be exposed. In some embodiments, such a shielding structure may employ features, e.g., full tape thickness features, and such features may provide optimal electrical grounding and/or high electrical signal energy, e.g. RF signal, AC signal, etc., isolation, for example, from an input port to an output port of such a device. Some devices may be bi-directional, and input ports and output ports may be interchangeable.
(92) FIG. 21 depicts an exemplary embodiment of the invention. An LTCC filter device 2100 may be attached to a PCB 2110 according to embodiments of the invention, and may have a wrap-around ground structure. Such a wrap-around ground structure of LTCC device 2100, e.g. an LTCC filter, may be attached to a ground of PCB 2110.
(93) FIG. 22 depicts an exemplary embodiment of the invention. A PCB 2200 may be used for mounting, attachment, connection and/or use of devices according to embodiments of the invention. PCB 2200 may have one or more port connections 2210 and one or more electrical ground connections 2220. Ground connections 2220 may be ground plane cut-outs, and may constrain a position of leads, e.g. leads or legs of a filter, during a solder process, e.g. reflow soldering. Port connections 2210, e.g. traces, may be thin traces, and may provide surface tension that may prevent outflow of solder, for example, without a use of a solder mask, increasing efficiency and lowering cost of assembly. Ground connections 2220 may be stepped leg, e.g. a stepped leg cross section, may reduce an amount of solder needed to mount a shield to a PCB 2200, and may reduce a tendency of such a shield to move, or float, during an assembly process, e.g. reflow soldering. In some embodiments, thin lines may not be necessary. In other embodiments, a PCB 2200 may be fabricated with, for example, a full cut-out around a shield leg landing pad on such a PCB 2200, and electrically conductive ground vias that may be beneath such legs and/or ground contact may make electrical contact through a device's wrap-around, e.g. wrap-around shield. PCB 2200 may form a fourth side of an electrical shielding structure, according to embodiments of the invention.
(94) According to an exemplary embodiment of the invention, an LTCC filter may be constructed and mechanically attached to a PCB, and electrically operable connections may be made to allow measurement of an LTCC filter device. FIG. 23 shows an exemplary electrical performance result of such a measurement. An LTCC filter device may be constructed, and a shielding structure according to embodiments of the invention may be attached according to further embodiments of the invention. It may then be mechanically attached to a PCB, and after attachment, electrical operable connections may be made to allow measurement of a shielded LTCC filter device. FIG. 23 shows an exemplary electrical performance result of such a measurement. According to exemplary FIG. 23, performance within a passband frequency band may have no deviation or degradation in performance between a shielded or an unshielded LTCC filter, which may be a desired result. A shielded LTCC filter rejection performance 2300 has an increase in an electrical signal rejection in substantially all of a rejection band frequency band when compared to an unshielded LTCC filter performance 2310, which is an additional desired result. An increase in rejection may be, for example 20 decibels (dB), or another amount of increase of undesired electrical frequency signals.
(95) Also depicted by exemplary FIG. 23 may be a measure of reflected signal 2320, which may be proportional to a mismatch experienced by an electrical signal when entering a device or structure, e.g. an LTCC filter. A measurement of a reflected signal 2320, S11, may be shown for both an LTCC filter without a shield and an LTCC filter with a shield constructed and installed according to embodiments of the invention. This exemplary measurement may show there may be no significant deviation in electrical performance when a shield may be used, which may be a further desired result.
(96) Exemplary measurements may use, for example, through line de-embedding or other measurement techniques. Measurement techniques may be used to isolate electrical performance of a device under test (DUT), whether a control group device, e.g. an LTCC filter without a shield, a device with a shield constructed and installed according to embodiments of the invention, e.g. an LTCC filter with a shielding structure installed around it, or another device desired to have electrical performance measurements made and/or recorded.
(97) An exemplary method according to embodiments of the invention may be according to FIG. 24. An exemplary embodiment may be a method of shielding a surface mount device, e.g., an LTCC filter, an LTCC coupler, an LTCC power divider and/or combiner, or other LTCC devices and/or circuits. A method 2400 may start and may be to select a shield material having a metallic composition, another material having a metallic coating, another material having properties such that it may act as an electrical wall or shield, or a combination of such materials. Using such materials, a metallic structure, for example a shield or metallic shield, may be constructed 2410. Such structure may be a three-dimensional rectangular structure, for example a rectangular prism, or another solid structure that may be constructed to enclose, at least partially, a surface mount electrical device, e.g., an LTCC device, for mounting on a PCB, for mounting into a hybrid electrical circuit, or for inclusion, construction and/or assembly into other microelectronic circuits, components and/or systems. Such a structure may be a viscous material, e.g., a silver epoxy, that may be cured after application to, for example, harden such a material. Construction of a metallic structure 2410 may be, for example, by manufacturing a metallic rectangular prism into a shape that may extend to be around an LTCC surface mount electrical device or component, and may have apertures allowing passage of electrical signals, e.g., other than an electrical ground or ground signal, between an enclosed circuit and an external circuit, e.g., a circuit on a PCB, onto which such an LTCC device may be mounted. Construction of a metallic structure 2410 may be, for example, by applying a substance, e.g., a paste having a metallic content, an epoxy having a metallic content, or other such substance having metallic electrical properties, around at least three sides of a surface mount electrical device, e.g., an LTCC circuit or device, and each side may be fully or partially covered. Application of such a substance may be performed, for example, following attachment of a surface mount device to a PCB. Application may include physical application and/or attachment to an LTCC device and/or a PCB, and may include curing and/or hardening of such a substance, for example, into a conformed shape, and may be referred to as conformal coating, for example conformal coating of a silver epoxy around a surface mounted LTCC circuit or device.
(98) A metallic structure that may be constructed 2410, and such a structure may be attached to ground 2420. Such attachment to ground may be by physical attachment, mechanical attachment, operable electrical attachment, e.g., electrical coupl Back to patents
