Patent ID: 9516753
Filing Date: 2016-12-06
CPC Classification: H01L,H05K,Y10T

Claim Text:
1. A wiring substrate comprising: a core layer having one surface and another surface and including a through-hole penetrating the core layer from the one surface to the other surface of the core layer, wherein an inner wall surface of the through-hole extends continuously from the one surface of the core layer to the other surface of the core layer; a first metal layer formed directly on the inner wall surface of the through-hole, the first metal layer covering the entire inner wall surface of the through-hole and continuously extending from the one surface of the core layer to the other surface of the core layer; a second metal layer formed on the first metal layer; a third metal layer formed on the second metal layer toward the one surface of the core layer; a fourth metal layer formed on the second metal layer toward the other surface of the core layer; a first wiring layer formed toward the one surface of the core layer and including a first part of the first metal layer, a first part of the second metal layer, and the third metal layer that are formed toward the one surface of the core layer; a second wiring layer formed toward the other surface of the core layer and including a second part of the first metal layer, a second part of the second metal layer, and the fourth metal layer that are formed toward the other surface of the core layer; and a through-wiring formed in the through-hole and including a third part of the first metal layer, a third part of the second metal layer, a part of the third metal layer, and a part of the fourth metal layer that are formed in the through-hole; wherein, among the first, second, third, and fourth metal layers, only the first metal layer and the second metal layer are formed in a narrowest part of the through-hole, wherein the core layer and the inner wall surface of the through-hole are formed of an insulating resin, wherein the second metal layer covers the first metal layer in the through-hole and closes up the narrowest part of the through-hole, wherein a thickness of a part of the third metal layer that is formed on top of the one surface of the core layer is greater than a thickness of a part of the second metal layer that is formed on top of the one surface of the core layer, and wherein a thickness of a part of the fourth metal layer that is formed on top of the other surface of the core layer is greater than a thickness of a part of the second metal layer that is formed on top of the other surface of the core layer.