# US 11,310,917 B2 · Method for manufacturing substrate for flexible printed wiring board, and substrate for flexible printed wiring board > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,917 B2 - Document ID: US11310917B2 - Status: Granted - Kind: B2 - Application number: 17/020,936 - Filed: 2020-09-15 - Published: 2021-03-18 - Granted: 2022-04-19 - Earliest claimed: 2019-09-17 - Assignees: Nippon Mektron, Ltd. - Applicants: Nippon Mektron, Ltd. - Inventors: Toshihiro Higashira; Fuki Hatano - Web page: https://patentgrep.com/patent/US11310917B2 ## CPC - H05K 3/0064: {onto a polymeric substrate} - H05K 1/028: {Bending or folding regions of flexible printed circuits (H05K1/0283 takes precedence)} - H05K 1/036: {Multilayers with layers of different types} - H05K 1/0366: {reinforced, e.g. by fibres, fabrics (H05K1/036 takes precedence)} - H05K 1/0393: {Flexible materials (H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups)} - H05K 1/034: {containing halogen} - H05K 3/386: {by the use of an organic polymeric bonding layer, e.g. adhesive} - H05K 2201/015: Fluoropolymer, e.g. polytetrafluoroethylene [PTFE] - H05K 2201/0154: Polyimide - H05K 2201/0195: Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure - H05K 2201/068: wherein the coefficient of thermal expansion is important - H05K 2203/06: Lamination - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract Provided is a method for manufacturing a substrate for flexible printed wiring board, comprising a laminated body forming step and an integration step, wherein in the laminated body forming step, on an upper surface and a lower surface of a fluororesin layer having a modified surface, a first and second reinforcing resin layers having a coefficient of thermal expansion smaller than that of the fluororesin layer are respectively stacked through a first thermosetting adhesive, on the first reinforcing resin layer and/or the second reinforcing resin layer, a conductor layer is stacked through a second thermosetting adhesive, to form a laminated body, and in the integration step, the laminated body is heated and integrated at a temperature not lower than a curing temperature of the first and second thermosetting adhesives and lower than a melting point of the fluororesin layer. ## Claims ### Claim 1 A method for manufacturing a substrate for flexible printed wiring board, comprising a laminated body forming step and an integration step, wherein in the laminated body forming step, on an upper surface and a lower surface of a fluororesin layer having a modified surface, a first and second reinforcing resin layers having a coefficient of thermal expansion smaller than that of the fluororesin layer are respectively stacked through a first thermosetting adhesive, on the first reinforcing resin layer and/or the second reinforcing resin layer, a conductor layer is stacked through a second thermosetting adhesive, to form a laminated body, and in the integration step, the laminated body is heated and integrated at a temperature not lower than a curing temperature of the first and second thermosetting adhesives and lower than a melting point of the fluororesin layer, wherein the first thermosetting adhesive is formed over an entire surface of the fluororesin layer. ### Claim 2 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the laminated body forming step comprises: forming a first laminated body by stacking the first reinforcing resin layer and the second reinforcing resin layer respectively on the upper surface and the lower surface of the fluororesin layer through the first thermosetting adhesive; and forming a second laminated body as the laminated body by stacking a conductor layer on one or two surfaces of the first laminated body through the second thermosetting adhesive. ### Claim 3 A method for manufacturing a substrate for flexible printed wiring board, comprising a laminated body forming step and an integration step, wherein in the laminated body forming step, on an upper surface and a lower surface of a fluororesin layer having a modified surface, a first and second reinforcing resin layers having a coefficient of thermal expansion smaller than that of the fluororesin layer are respectively stacked through a first thermosetting adhesive, on the first reinforcing resin layer and/or the second reinforcing resin layer, a single-sided conductor-clad laminate including a conductor layer and a third reinforcing resin layer stacked on one surface of the conductor layer is stacked through a second thermosetting adhesive so that the conductor layer faces outward, to form a laminated body, and in the integration step, the laminated body is heated and integrated at a temperature not lower than a curing temperature of the first and second thermosetting adhesives and lower than a melting point of the fluororesin layer. ### Claim 4 (depends on 3) The method for manufacturing the substrate for flexible printed wiring board according to claim 3, wherein the laminated body forming step comprises: forming a first laminated body by stacking the first reinforcing resin layer and the second reinforcing resin layer respectively on the upper surface and the lower surface of the fluororesin layer through the first thermosetting adhesive; preparing the single-sided conductor-clad laminate having the conductor layer, and the third reinforcing resin layer stacked on one surface of the conductor layer; and forming a second laminated body as the laminated body by stacking the single-sided conductor-clad laminate on one or two surfaces of the first laminated body so that the third reinforcing resin layer is bonded to the first laminated body through the second thermosetting adhesive. ### Claim 5 A method for manufacturing a substrate for flexible printed wiring board, comprising: preparing a fluororesin layer having a modified surface; preparing a first single-sided conductor-clad laminate including a first conductor layer and a first reinforcing resin layer stacked on one surface of the first conductor layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; preparing a second single-sided conductor-clad laminate including a second conductor layer and a second reinforcing resin layer stacked on one surface of the second conductor layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; and a laminated body forming step and an integration step, wherein in the laminated body forming step, on an upper surface of the fluororesin layer, the first single-sided conductor-clad laminate is stacked through a first thermosetting adhesive so that the first conductor layer faces outward, on a lower surface of the fluororesin layer, the second single-sided conductor-clad laminate is stacked through a second thermosetting adhesive so that the second conductor layer faces outward, to form a laminated body, and in the integration step, the laminated body is heated and integrated at a temperature not lower than a curing temperature of the first and second thermosetting adhesives and lower than a melting point of the fluororesin layer, wherein the first thermosetting adhesive is formed over an entire surface of the fluororesin layer. ### Claim 6 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the integration step comprises heating the laminated body at a temperature of 250° C. or lower. ### Claim 7 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the first and second reinforcing resin layers have a coefficient of thermal expansion of 30 ppm/° C. or less. ### Claim 8 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the first and second reinforcing resin layers have a coefficient of thermal expansion of 50 ppm/° C. or less and an elastic modulus of 3 GPa or more. ### Claim 9 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the first and second reinforcing resin layers have an elastic modulus of 3 GPa or more. ### Claim 10 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the first and second reinforcing resin layers are made of liquid crystal polymer (LCP), polyetheretherketone (PEEK), or polyimide. ### Claim 11 (depends on 1) The method for manufacturing the substrate for flexible printed wiring board according to claim 1, wherein the conductor layer has a ten-point average roughness of 2.0 μm or less. ### Claim 12 (depends on 5) The method for manufacturing the substrate for flexible printed wiring board according to claim 5, wherein the first and second conductor layers have a ten-point average roughness of 2.0 μm or less. ### Claim 13 A substrate for flexible printed wiring board, comprising: a fluororesin layer having a modified surface; a first reinforcing resin layer stacked on an upper surface of the fluororesin layer through a first cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; a second reinforcing resin layer stacked on a lower surface of the fluororesin layer through a second cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; and a conductor layer stacked on the first reinforcing resin layer and/or the second reinforcing resin layer through a third cured adhesive layer, wherein the first cured adhesive layer is formed over an entire surface of the fluororesin layer. ### Claim 14 A substrate for flexible printed wiring board, comprising: a fluororesin layer having a modified surface; a first reinforcing resin layer stacked on an upper surface of the fluororesin layer through a first cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; a second reinforcing resin layer stacked on a lower surface of the fluororesin layer through a second cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; a third reinforcing resin layer stacked on the first reinforcing resin layer and/or the second reinforcing resin layer through a third cured adhesive layer; and a conductor layer stacked on the third reinforcing resin layer. ### Claim 15 A substrate for flexible printed wiring board, comprising: a fluororesin layer having a modified surface; a first reinforcing resin layer stacked on an upper surface of the fluororesin layer through a first cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; a second reinforcing resin layer stacked on a lower surface of the fluororesin layer through a second cured adhesive layer and having a coefficient of thermal expansion smaller than that of the fluororesin layer; and a conductor layer stacked on the first reinforcing resin layer and/or the second reinforcing resin layer, wherein the first cured adhesive layer is formed over an entire surface of the fluororesin layer.