US Patent No. 10,602,622

WIRING BOARD


Patent No. 10,602,622
Issue Date March 24, 2020
Title Wiring Board
Inventorship Masaaki Harazono, Kirishima (JP)
Takayuki Umemoto, Omihachiman (JP)
Hidetoshi Yugawa, Kyoto (JP)
Assignee KYOCERA Corporation, Kyoto-Shi, Kyoto (JP)

Claim of US Patent No. 10,602,622

1. A wiring board comprising:a first insulating layer that has a surface with a first level difference of unevenness;
a second insulating layer that is laminated on the first insulating layer and has a surface with a second level difference of unevenness, wherein the second insulating layer is made of an insulating material of same type as an insulating material of the first insulating layer;
a plurality of insulating particles contained in each of the first insulating layer and the second insulating layer, wherein the insulating particles contained in each of the first insulating layer and the second insulating layer include partly exposed particles that are exposed at the surface of the first insulating layer and the surface of the second insulating layer respectively and form the first level difference of unevenness and the second level difference of unevenness;
a first underlying metal layer positioned on the surface of the first insulating layer;
a second underlying metal layer positioned on the surface of the second insulating layer, wherein the second level difference of the unevenness is smaller than the first level difference;
a first wiring conductor on the first underlying metal layer; and
a second wiring conductor on the second underlying metal layer,
wherein an area rate of exposed portions of the partly exposed particles occupying in the surface of the first insulating layer is 20 to 30% when viewed in plan, and the area rate of exposed portions of the partly exposed particles occupying in the surface of the second insulating layer is 5 to 12% when viewed in plan.