# US 7,607,350 B2 · Circuit board mounting for temperature stress reduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,350 B2 - Document ID: US7607350B2 - Status: Granted - Kind: B2 - Application number: 11/244,464 - Filed: 2005-10-06 - Published: 2007-04-12 - Granted: 2009-10-27 - Earliest claimed: 2005-10-06 - Assignees: Northrop Grumman Guidance and Electronics Company, Inc. - Inventors: Youngmin A. Choi - Web page: https://patentgrep.com/patent/US7607350B2 ## CPC - H05K 7/1417: {having securing means for mounting boards, plates or wiring boards (H05K7/1461 takes precedence)} - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A circuit board mounting system in one example comprises an improved mounting system for a circuit board disposed between housing elements, wherein the improvement comprises a plurality of slots formed in the circuit board and a plurality of bushings disposed within the slots, such that the housing elements rest on opposed ends of the bushings, and the circuit board moves in a plane substantially parallel to its mounting surfaces in response to changes in temperature, thus reducing thermal stress. ## Claims ### Claim 1 An improved mounting system for a circuit board disposed between housing elements, the improvement comprising: a plurality of slots formed in the circuit board; a plurality of bushings disposed within the slots, the slots being moveable relative to the bushings, wherein the plurality of bushings are formed from Kovar; such that the housing elements rest on opposed ends of the bushings, and the circuit board moves in a plane substantially parallel to the mounting surfaces of the circuit board in response to changes in temperature, thus reducing thermal stress during operation of the mounting system. ### Claim 2 (depends on 1) The improved mounting system of claim 1, wherein the circuit board is substantially circular, and movement in a plane substantially parallel to the mounting surfaces of the circuit board comprises movement along a circuit board radius. ### Claim 3 (depends on 2) The improved mounting system of claim 2, wherein the slots are radially disposed in the circuit board. ### Claim 4 (depends on 1) The improved mounting system of claim 1, wherein the bushings are substantially cylindrical. ### Claim 5 (depends on 4) The improved mounting system of claim 4, wherein the bushings further include integrally formed flanges disposed at opposing ends of the bushings. ### Claim 6 (depends on 1) The improved mounting system of claim 1, wherein the bushings are restrained within the slots by an application of compliant adhesive. ### Claim 7 (depends on 2) The improved mounting system of claim 2, wherein the compliant adhesive comprises an epoxy resin. ### Claim 8 (depends on 1) The improved mounting system of claim 1, wherein the slots are disposed proximate a circuit board perimeter. ### Claim 9 (depends on 8) The improved mounting system of claim 8, wherein the slots extend through the circuit board perimeter, providing openings therein. ### Claim 10 (depends on 1) The improved mounting system of claim 1, wherein the housing elements further comprise a first housing element corresponding to an upper housing, and a second housing element corresponding to a header assembly. ### Claim 11 A method for mounting a circuit board, the method comprising the steps of: providing a circuit board disposed within first and second housing elements; providing a plurality of slots in the circuit board; disposing a plurality of bushings within the slots; and the slots being moveable relative to the bushings, wherein the plurality of bushings are formed from Kovar; and resting the housing elements on opposed ends of the bushings; such that the circuit board moves in a plane substantially parallel to the mounting surfaces of the circuit board in response to changes in temperature, thus reducing thermal stress during operation of the mounting the circuit board. ### Claim 12 (depends on 11) The method in accordance with claim 11, wherein the circuit board is substantially circular, and the step of providing a plurality of slots further comprises the step of providing a plurality of slots radially disposed in the circuit board. ### Claim 13 (depends on 11) The method in accordance with claim 11, wherein the step of disposing a plurality of bushings within the slots further comprises the step of disposing a plurality of substantially cylindrical bushings within the slots, and wherein the cylindrical bushings include integrally formed flanges disposed at opposing ends of the bushings. ### Claim 14 (depends on 13) The method in accordance with claim 13, wherein the step of disposing a plurality of bushings within the slots further comprises the step of restraining the cylindrical bushings within the slots by an application of compliant adhesive. ### Claim 15 (depends on 12) The method in accordance with claim 12, wherein the step of providing a plurality of slots radially disposed in the circuit board further comprises the step of providing a plurality of radially disposed slots proximate a circuit board perimeter. ### Claim 16 An electromechanical assembly comprising: an upper housing element; an electrical connection header assembly; a circuit board disposed between the upper housing element and the electrical header assembly, wherein the circuit board further includes: a plurality of slots formed in the circuit board; and a plurality of bushings disposed within the slots, the slots being moveable relative to the bushings, wherein the plurality of bushings are formed from Kovar; such that the upper housing element and the electrical header assembly rest on opposed ends of the bushings, and the circuit board moves in a plane substantially parallel to the mounting surfaces in response to changes in temperature, thus reducing thermal stress during operation of the electro-mechanical assembly. ### Claim 17 (depends on 16) The electro-mechanical assembly of claim 16, wherein the circuit board is substantially circular, and movement in a plane substantially parallel to the mounting surfaces of the circuit board comprises movement along a circuit board radius. ### Claim 18 (depends on 17) The electro-mechanical assembly of claim 17, wherein the slots are radially disposed in the circuit board. ### Claim 19 (depends on 16) The electro-mechanical assembly of claim 16, wherein the bushings are substantially cylindrical. ### Claim 20 (depends on 19) The electro-mechanical assembly of claim 19, wherein the bushings further include integrally formed flanges disposed at opposing ends of the bushings. ### Claim 21 A hemispherical resonator gyro comprising: a resonator disposed within interior and exterior support structures; an upper housing element; an electrical connection header assembly making electrical contact with the resonator; a circuit board disposed between the upper housing element and the electrical header assembly, wherein the circuit board further includes: a plurality of slots formed in the circuit board; and a plurality of bushings disposed within the slots, the slots being moveable relative to the bushings, wherein the plurality of bushings are formed from Kovar; such that the upper housing element and the electrical header assembly rest on opposed ends of the bushings, and the circuit board moves in a plane substantially parallel to the mounting surfaces of the circuit board in response to changes in temperature, thus reducing thermal stress during operation of the hemispherical resonator gyro. ### Claim 22 (depends on 1) The improved mounting system of claim 1, wherein the circuit board is a polyclad polyimide circuit board. ### Claim 23 (depends on 1) The improved mounting system of claim 1, wherein the circuit board expands and contracts with the temperature at a different rate than the housing elements. ### Claim 24 (depends on 1) The improved mounting system of claim 1, wherein an opening is provided through each of the plurality of bushings to accommodate mounting screws, studs, or other mounting features. ### Claim 25 (depends on 1) The improved mounting system of claim 1, wherein the slots are one of open-ended and completely surrounded by material of the circuit board. ### Claim 26 (depends on 11) The method of claim 11, wherein the slots are one of open-ended and completely surrounded by material of the circuit board. ### Claim 27 (depends on 16) The electro-mechanical assembly of claim 16, wherein the slots are one of open-ended and completely surrounded by material of the circuit board. ### Claim 28 (depends on 21) The hemispherical resonator gyro of claim 21, wherein the slots are one of open-ended and completely surrounded by material of the circuit board. ### Claim 29 A hemispherical resonator gyro comprising: a resonator disposed within interior and exterior support structures; an upper housing element; an electrical connection header assembly operatively coupled to the resonator; a circuit board disposed between the upper housing element and the electrical header assembly, wherein the circuit board further includes: a plurality of slots formed in the circuit board, the slots being one of open-ended and completely surrounded by material of the circuit board; and a plurality of bushings disposed within the slots, the slots being moveable relative to the bushings and at least some of the slots having a plurality of bushings, wherein the plurality of bushings are formed from Kovar; a predetermined amount of a compliant epoxy disposed between each of the bushings and a respective slot; the header assembly being in close mechanical contact with respective bushings of the plurality of bushings rather than the circuit board, and the upper housing element being in close mechanical contact with respective bushings of the plurality of bushings rather than the circuit board; and the header assembly, the upper housing element, and the circuit board having different coefficients of thermal expansion; such that the upper housing element and the electrical header assembly rest on opposed ends of the bushings, and the circuit board moves in a plane substantially parallel to the mounting surfaces of the circuit board in response to changes in temperature, thus reducing thermal stress during operation of the hemispherical resonator gyro.