# US 10,485,102 B2 · Substrate for high-frequency 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 10,485,102 B2 - Document ID: US10485102B2 - Status: Granted - Kind: B2 - Application number: 16/336,211 - Filed: 2018-06-20 - Published: 2019-07-11 - Granted: 2019-11-19 - Earliest claimed: 2017-08-08 - Assignees: Sumitomo Electric Industries, Ltd.; Sumitomo Electric Printed Circuits, Inc. - Applicants: Sumitomo Electric Industries, Ltd.; Sumitomo Electric Printed Circuits, Inc. - Inventors: Shingo Kaimori; Masaaki Yamauchi; Kentaro Okamoto; Satoshi Kiya; Kazuo Murata - Web page: https://patentgrep.com/patent/US10485102B2 ## CPC - H05K 1/0373: {containing additives, e.g. fillers (H05K1/036 takes precedence)} - B32B 15/08: of synthetic resin - B32B 15/082: comprising vinyl resins; comprising acrylic resins - B32B 15/20: comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)} - B32B 27/20: using fillers, pigments, thixotroping agents - B32B 27/30: comprising vinyl {(co)polymers; comprising acrylic (co)polymers} - H05K 1/0271: {Arrangements for reducing stress or warp in rigid printed circuit boards, e.g. caused by loads, vibrations or differences in thermal expansion} - H05K 1/03: Use of materials for the substrate - H05K 1/034: {containing halogen} - H05K 1/09: Use of materials for the {conductive, e.g. } metallic pattern - H05K 3/0055: {After-treatment, e.g. cleaning or desmearing of holes} - H05K 3/381: {by special treatment of the substrate} - H05K 2201/015: Fluoropolymer, e.g. polytetrafluoroethylene [PTFE] - H05K 2201/0209: Inorganic, non-metallic particles - H05K 2201/0269: Non-uniform distribution or concentration of particles - H05K 2201/029: Woven fibrous reinforcement or textile - H05K 2201/0355: Metal foils - H05K 2201/068: wherein the coefficient of thermal expansion is important - H05K 2203/1194: Thermal treatment leading to a different chemical state of a material, e.g. annealing for stress-relief, aging - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM ## Abstract A first embodiment of a substrate for a high-frequency printed wiring board according to the present disclosure is directed to a substrate for a high-frequency printed wiring board, the substrate including: a dielectric layer including a fluororesin and an inorganic filler; and a copper foil layered on at least one surface of the dielectric layer, wherein a surface of the copper foil at the dielectric layer side has a maximum height roughness (Rz) of less than or equal to 2 μm, and a ratio of the number of inorganic atoms of the inorganic filler to the number of fluorine atoms of the fluororesin in a superficial region of the dielectric layer at the copper foil side is less than or equal to 0.08. ## Claims ### Claim 1 A substrate for a high-frequency printed wiring board, the substrate comprising: a dielectric layer including a fluororesin and an inorganic filler; and a copper foil layered on at least one surface of the dielectric layer, wherein a surface of the copper foil at the dielectric layer side has a maximum height roughness (Rz) of less than or equal to 2 μm, a ratio of the number of inorganic atoms of the inorganic filler to the number of fluorine atoms of the fluororesin in a superficial region of the dielectric layer at the copper foil side is less than or equal to 0.08, and a softening temperature of the fluororesin is more than or equal to 250° C. and less than or equal to 310° C. ### Claim 2 (depends on 1) The substrate for a high-frequency printed wiring board according to claim 1, wherein the fluororesin is a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polytetrafluoroethylene, or a combination of the tetrafluoroethylen e-hexafluoropropylene copolymer, the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and the polytetrafluoroethylene. ### Claim 3 (depends on 2) The substrate for a high-frequency printed wiring board according to claim 2, wherein the fluororesin is the tetrafluoroethylene-hexafluoropropylene copolymer. ### Claim 4 (depends on 1) The substrate for a high-frequency printed wiring board according to claim 1, wherein a mass ratio of the inorganic filler to the fluororesin in the dielectric layer is more than or equal to 1.0. ### Claim 5 (depends on 1) The substrate for a high-frequency printed wiring board according to claim 1, wherein the inorganic filler includes silica. ### Claim 6 (depends on 1) The substrate for a high-frequency printed wiring board according to claim 1, wherein a linear expansion coefficient of the substrate in a thickness direction is less than or equal to 50 ppm/K. ### Claim 7 (depends on 1) The substrate for a high-frequency printed wiring board according to claim 1, wherein a change of permittivity of the substrate by a temperature in a range of 25° C. to 120° C. is less than or equal to 2%. ### Claim 8 A substrate for a high-frequency printed wiring board, the substrate comprising: a dielectric layer including a fluororesin and an inorganic filler; and a copper foil layered on at least one surface of the dielectric layer, wherein a surface of the copper foil at the dielectric layer side has a maximum height roughness (Rz) of less than or equal to 2 μm, and in a cross section of the dielectric layer in a direction perpendicular to the copper foil, a ratio of a total cross sectional area of the inorganic filler to an overall cross sectional area in a region at a distance of more than or equal to 18 μm and less than or equal to 22 μm from the copper foil is 0.7 time or less as large as a ratio of a total cross sectional area of the inorganic filler to an overall cross sectional area in a region at a distance of more than or equal to 0 μm and less than or equal to 2 μm from the copper foil.