Wiring substrate
A wiring substrate includes a core substrate, a build-up part formed on a surface of the substrate and including insulating layers and conductor layers, and a covering insulating layer formed on the build-up part such that the covering layer is covering the outermost surface of the build-up part. The build-up part is formed such that the insulating layers include a first insulating layer forming the outermost one of the insulating layers, that the conductor layers include a first conductor layer formed on the first insulating layer and including a first conductor pad, and that a tensile strength of the first insulating layer is higher than a tensile strength of each insulating layer other than the first insulating layer in the first build-up part, and the covering layer is formed such that the covering layer has opening entirely exposing an upper surface and a side surface of the first conductor pad.
1 . A wiring substrate, comprising:
a core substrate;
a first build-up part formed on a first surface of the core substrate and comprising a plurality of insulating layers and a plurality of conductor layers;
a second build-up part formed on a second surface of the core substrate on an opposite side with respect to the first surface of the core substrate and comprising a conductor layer;
a first covering insulating layer formed on the first build-up part such that the first covering insulating layer is covering an outermost surface of the first build-up part; and
a second covering insulating layer formed on the second build-up part such that the second covering insulating layer is covering an outermost surface of the second build-up part,
wherein the first build-up part is formed such that the plurality of insulating layers includes a first insulating layer forming an outermost one of the insulating layers, that the plurality of conductor layers is laminated on the insulating layers respectively and includes a first conductor layer formed on the first insulating layer and including a plurality of first conductor pads, and that a tensile strength of the first insulating layer is higher than a tensile strength of each of the insulating layers other than the first insulating layer in the first build-up part, the first covering insulating layer is formed such that the first covering insulating layer has a plurality of openings entirely exposing upper surfaces and side surfaces of the first conductor pads, respectively, and the second covering insulating layer has a plurality of openings exposing portions of the conductor layer in the second build-up part respectively such that the openings of the second covering insulating layer define a plurality of second conductor pads, respectively.
2 . The wiring substrate according to claim 1 , wherein the first build-up part is formed such that each of the first conductor pads of the first conductor layer is not directly connected to another pad in the first conductor layer or a wiring in the first conductor layer.
3 . The wiring substrate according to claim 1 , wherein the first build-up part is formed such that the tensile strength of the first insulating layer is 125 MPa or greater.
4 . The wiring substrate according to claim 1 , wherein the first build-up part is formed such that the first insulating layer has a dielectric loss tangent of 0.013 or less at a frequency of 5.8 GHz.
5 . The wiring substrate according to claim 1 , wherein the second build-up part is formed such that the second build-up part includes a plurality of insulating layers and that a number of the insulating layers in the second build-up part is equal to a number of the insulating layers in the first build-up part.
6 . The wiring substrate according to claim 5 , wherein the second build-up part is formed such that the first insulating layer in the first build-up part and the outermost insulating layer in the second build-up part are formed of a same material.
7 . The wiring substrate according to claim 1 , wherein the first build-up part is formed such that the plurality of conductor layers includes a second conductor layer formed on an opposite side with respect to the first conductor layer via the first insulating layer and that the first build-up part includes a plurality of via conductors penetrating through the first insulating layer and connecting the second conductor layer and the first conductor pads of the first conductor layer, respectively.
8 . The wiring substrate according to claim 2 , wherein the first build-up part is formed such that the tensile strength of the first insulating layer is 125 MPa or greater.
9 . The wiring substrate according to claim 2 , wherein the first build-up part is formed such that the first insulating layer has a dielectric loss tangent of 0.013 or less at a frequency of 5.8 GHz.
10 . The wiring substrate according to claim 2 , wherein the second build-up part is formed such that the second build-up part includes a plurality of insulating layers and that a number of the insulating layers in the second build-up part is equal to a number of the insulating layers in the first build-up part.
11 . The wiring substrate according to claim 10 , wherein the second build-up part is formed such that the first insulating layer in the first build-up part and the outermost insulating layer in the second build-up part are formed of a same material.
12 . The wiring substrate according to claim 2 , wherein the first build-up part is formed such that the plurality of conductor layers includes a second conductor layer formed on an opposite side with respect to the first conductor layer via the first insulating layer and that the first build-up part includes a plurality of via conductors penetrating through the first insulating layer and connecting the second conductor layer and the first conductor pads of the first conductor layer, respectively.
13 . The wiring substrate according to claim 3 , wherein the first build-up part is formed such that the first insulating layer has a dielectric loss tangent of 0.013 or less at a frequency of 5.8 GHz.
14 . The wiring substrate according to claim 3 , wherein the second build-up part is formed such that the second build-up part includes a plurality of insulating layers and that a number of the insulating layers in the second build-up part is equal to a number of the insulating layers in the first build-up part.
15 . The wiring substrate according to claim 14 , wherein the second build-up part is formed such that the first insulating layer in the first build-up part and the outermost insulating layer in the second build-up part are formed of a same material.
16 . The wiring substrate according to claim 3 , wherein the first build-up part is formed such that the plurality of conductor layers includes a second conductor layer formed on an opposite side with respect to the first conductor layer via the first insulating layer and that the first build-up part includes a plurality of via conductors penetrating through the first insulating layer and connecting the second conductor layer and the first conductor pads of the first conductor layer, respectively.
17 . The wiring substrate according to claim 4 , wherein the second build-up part is formed such that the second build-up part includes a plurality of insulating layers and that a number of the insulating layers in the second build-up part is equal to a number of the insulating layers in the first build-up part.
18 . The wiring substrate according to claim 17 , wherein the second build-up part is formed such that the first insulating layer in the first build-up part and the outermost insulating layer in the second build-up part are formed of a same material.
19 . The wiring substrate according to claim 4 , wherein the first build-up part is formed such that the plurality of conductor layers includes a second conductor layer formed on an opposite side with respect to the first conductor layer via the first insulating layer and that the first build-up part includes a plurality of via conductors penetrating through the first insulating layer and connecting the second conductor layer and the first conductor pads of the first conductor layer, respectively.
20 . The wiring substrate according to claim 5 , wherein the first build-up part is formed such that the plurality of conductor layers includes a second conductor layer formed on an opposite side with respect to the first conductor layer via the first insulating layer and that the first build-up part includes a plurality of via conductors penetrating through the first insulating layer and connecting the second conductor layer and the first conductor pads of the first conductor layer, respectively.