Wiring substrate
A wiring substrate includes a core substrate having a through-hole conductor, a resin insulating layer formed on the core substrate, a conductor layer formed on the insulating layer and including a seed layer and an electrolytic plating layer, and a via conductor formed in the insulating layer. The via conductor electrically connects the through-hole conductor and conductor layer. The via conductor includes the seed layer and electrolytic plating layer extending from the conductor layer. The core substrate includes a glass substrate and has a through hole penetrating through the glass substrate. The through-hole conductor is formed in the through hole. The seed layer is covering inner wall surface of the insulating layer in opening in which the via conductor is formed. The seed layer has a first portion and a second portion electrically connected to the first portion. That part of the first portion is formed on the second portion.
1 . A wiring substrate, comprising:
a core substrate having a through-hole conductor;
a resin insulating layer formed on the core substrate;
a conductor layer formed on the resin insulating layer and comprising a seed layer and an electrolytic plating layer formed on the seed layer; and
a via conductor formed in the resin insulating layer such that the via conductor electrically connects the through-hole conductor and the conductor layer and that the via conductor includes the seed layer and electrolytic plating layer extending from the conductor layer,
wherein the core substrate includes a glass substrate and has a through hole penetrating through the glass substrate such that the through-hole conductor is formed in the through hole, and the via conductor is formed such that the seed layer is covering an inner wall surface of the resin insulating layer in an opening in which the via conductor is formed, that the seed layer has a first portion and a second portion electrically connected to the first portion and that a part of the first portion is formed on the second portion.
2 . The wiring substrate according to claim 1 , wherein the seed layer in the via conductor is formed such that a leading end of the first portion is formed on a trailing end of the second portion.
3 . The wiring substrate according to claim 1 , wherein the seed layer in the via conductor is formed such that the first portion and the second portion are formed in a same process.
4 . The wiring substrate according to claim 1 , wherein the via conductor is formed such that the seed layer in the via conductor has a step-shaped cross section.
5 . The wiring substrate according to claim 1 , wherein the via conductor is formed such that the seed layer includes a first layer covering the inner wall surface of the resin insulating layer in the opening and a second layer formed on the first layer and that the first layer has the first portion and the second portion.
6 . The wiring substrate according to claim 5 , wherein the seed layer in the via conductor is formed such that a leading end of the first portion is formed on a trailing end of the second portion.
7 . The wiring substrate according to claim 5 , wherein the via conductor is formed such that the first layer of the seed layer has a step-shaped cross section.
8 . The wiring substrate according to claim 1 , wherein the resin insulating layer includes resin, first inorganic particles and second inorganic particles such that the first inorganic particles have flat parts and that the resin and the flat parts of the first inorganic particles are forming the inner wall surface in the opening.
9 . The wiring substrate according to claim 8 , wherein the resin insulating layer is formed such that the inner wall surface in the opening has steps formed between the resin and the flat parts of the first inorganic particles.
10 . The wiring substrate according to claim 1 , wherein the conductor layer and via conductor are formed such that the seed layer includes an alloy comprising copper, aluminum, and at least one metal selected from the group consisting of nickel, zinc, gallium, silicon, and magnesium.
11 . The wiring substrate according to claim 10 , wherein the at least one metal of the alloy in the seed layer includes silicon.
12 . The wiring substrate according to claim 10 , wherein the seed layer in the conductor layer and via conductor is formed such that a content of the aluminum in the alloy is in a range of 1.0 at % to 15.0 at %.
13 . The wiring substrate according to claim 10 , wherein the seed layer in the conductor layer and via conductor is formed such that the alloy includes carbon in a content of 50 ppm or less.
14 . The wiring substrate according to claim 10 , wherein the seed layer in the conductor layer and via conductor is formed such that the alloy includes oxygen in a content of 100 ppm or less.
15 . The wiring substrate according to claim 11 , wherein the seed layer in the conductor layer and via conductor is formed such that a content of the silicon in the alloy is in a range of 0.5 at % to 10.0 at %.
16 . The wiring substrate according to claim 11 , wherein the seed layer in the conductor layer and via conductor is formed such that a content of the aluminum in the alloy is in a range of 1.0 at % to 15.0 at %.
17 . The wiring substrate according to claim 11 , wherein the seed layer in the conductor layer and via conductor is formed such that the alloy includes carbon in a content of 50 ppm or less and oxygen in a content of 100 ppm or less.
18 . A method for manufacturing a wiring substrate, comprising:
forming a core substrate having a through-hole conductor;
forming a resin insulating layer on the core substrate;
forming a conductor layer on the resin insulating layer such that the conductor layer includes a seed layer and an electrolytic plating layer formed on the seed layer; and
forming a via conductor in the resin insulating layer such that the via conductor electrically connects the through-hole conductor and the conductor layer and that the via conductor includes the seed layer and electrolytic plating layer extending from the conductor layer,
wherein the forming the core substrate includes forming a through hole penetrating through a glass substrate and forming the through-hole conductor in the through hole, and the forming the via conductor includes forming the seed layer in an opening formed in the resin insulating layer such that the seed layer covers an inner wall surface of the resin insulating layer in the opening, that the seed layer has a first portion and a second portion electrically connected to the first portion and that a part of the first portion is formed on the second portion.
19 . The method for manufacturing a wiring substrate according to claim 18 , wherein the forming the resin insulating layer includes forming the resin insulating layer comprising resin and inorganic particles, and the forming the via conductor includes forming the opening in the resin insulating layer such that the inorganic particles have protruding portions protruding from the resin forming the inner wall surface in the opening, and removing the protruding portions of the inorganic particles.
20 . The wiring substrate according to claim 18 , wherein the forming the resin insulating layer includes forming the resin insulating layer comprising resin and inorganic particles, and the forming the via conductor includes forming the opening in the resin insulating layer such that the inorganic particles have protruding portions protruding from the resin forming the inner wall surface in the opening, and removing the protruding portions of the inorganic particles such that the inner wall surface in the opening includes exposed surfaces of the inorganic particles.