# US 9,560,746 B1 · Stress relief for rigid components on flexible circuits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,560,746 B1 - Document ID: US9560746B1 - Status: Granted - Kind: B1 - Application number: 14/604,476 - Filed: 2015-01-23 - Granted: 2017-01-31 - Earliest claimed: 2014-01-24 - Assignees: Multek Technologies Limited - Applicants: Multek Technologies, Ltd. - Inventors: Mark Bergman; Michael James Glickman - Web page: https://patentgrep.com/patent/US9560746B1 ## CPC - H05K 1/189: characterised by the use of flexible or folded printed circuits - H05K 2201/0154: Polyimide - H05K 2201/10378: Interposers - H05K 2201/2009: Reinforced areas, e.g. for a specific part of a flexible printed circuit - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract In order to limit the stress and strain applied to a printed circuit board while still maintaining flexibility, multiple small rigid mesas are formed on a flexible printed circuit, where the rigid mesas are physically isolated by trenches formed around their perimeters. Individual electronic components are attached to the multiple rigid mesas. These trenches form openings at which the printed circuit board is enabled to flex, bend or twist, thereby minimizing, if not eliminating, resulting stress applied to the interconnection between the electronic components and the rigid mesas. ## Claims ### Claim 1 A circuit board comprising: a. a flexible printed circuit comprising a first exterior surface and a second exterior surface opposite the first exterior surface; b. a plurality of rigid sections coupled to the first exterior surface, wherein each rigid section is physically separated from each other rigid section, and each rigid section includes one or more electrical pads, further wherein each rigid section comprises a first rigid section surface and a second rigid section surface opposite the first rigid section surface, wherein an entire footprint of each first rigid section surface is coupled to the first exterior surface of the flexible printed circuit; and c. a plurality of electronic components, one electrical component coupled to a corresponding one rigid section at the second rigid section surface such that the one electrical component, the one rigid section and the flexible printed circuit form a stack. ### Claim 2 (depends on 1) The circuit board of claim 1 wherein the flexible printed circuit comprises a plurality of stacked layers. ### Claim 3 (depends on 2) The circuit board of claim 2 wherein the plurality of stacked layers comprises a plurality of alternating flexible layers and electrically conductive layers. ### Claim 4 (depends on 3) The circuit board of claim 3 wherein each flexible layer comprises polyimide or other polymer material. ### Claim 5 (depends on 3) The circuit board of claim 3 wherein each electrically conductive layer comprises patterned electrically conductive interconnects. ### Claim 6 (depends on 3) The circuit board of claim 3 wherein each rigid section has a higher elastic modulus than each flexible layer. ### Claim 7 (depends on 6) The circuit board of claim 6 wherein each rigid section is made of a different material than each flexible layer. ### Claim 8 (depends on 6) The circuit board of claim 6 wherein each rigid section is made of the same material as each flexible layer, and each rigid section is thicker than each flexible layer. ### Claim 9 (depends on 1) The circuit board of claim 1 further comprising a plurality of vias wherein each via is coupled to one of the electrical pads of the rigid section and to an electrically conductive layer in the flexible printed circuit. ### Claim 10 (depends on 9) The circuit board of claim 9 wherein each electronic component comprises a plurality of connection pads, one connection pad coupled to a corresponding one electrical pad on the rigid section. ### Claim 11 (depends on 1) The circuit board of claim 1 wherein each rigid section consists of one of polyimide or other polymer material, a glass-reinforced polymer, or a printable polymer. ### Claim 12 (depends on 1) The circuit board of claim 1 wherein each rigid section has a higher elastic modulus than the flexible printed circuit. ### Claim 13 (depends on 1) The circuit board of claim 1 wherein each rigid section is made of a different material than the flexible printed circuit. ### Claim 14 (depends on 1) The circuit board of claim 1 further comprising one or more additional rigid sections coupled to the second exterior surface of the flexible printed circuit, wherein the one or more additional rigid sections increase an overall rigidity of the circuit board. ### Claim 15 (depends on 1) The circuit board of claim 1 further comprising: a. another plurality of rigid sections coupled to the second exterior surface, wherein each rigid section of the other plurality is physically separated from each other rigid section of the other plurality, and each rigid section of the other plurality includes one or more electrical pads; and c. another plurality of electronic components, one electrical component of the other plurality coupled to a corresponding one rigid section of the other plurality. ### Claim 16 (depends on 15) The circuit board of claim 15 further comprising another plurality of vias wherein each via of the other plurality is coupled to one of the electrical pads of the rigid section of the other plurality and to an electrically conductive layer in the flexible printed circuit. ### Claim 17 (depends on 16) The circuit board of claim 16 wherein each electronic component of the other plurality comprises a plurality of connection pads, one connection pad coupled to a corresponding one electrical pad on the rigid section of the other plurality. ### Claim 18 A circuit board comprising: a. a flexible printed circuit comprising an exterior surface; b. a plurality of rigid sections coupled to the exterior surface, wherein each rigid section is physically separated from each other rigid section, and each rigid section includes an electrical pad; and c. a plurality of electronic components wherein each electronic component comprises a plurality of connection pads, one connection pad is coupled to the electrical pad of a corresponding one rigid section. ### Claim 19 A circuit board comprising: a. a flexible printed circuit comprising an exterior surface having a plurality of electrical pads; b. a plurality of rigid sections positioned within the flexible printed circuit, wherein each rigid section is physically separated from each other rigid section; and c. a plurality of electronic components wherein each electronic component comprises a plurality of connection pads, wherein one connection pad is coupled to a corresponding electrical pad on the exterior surface of the flexible printed circuit.