Manufacturing method of double-sided wiring glass substrate
To improve thermal resistance of a double-sided wiring glass substrate. A through-hole is filled with a copper post composed of metallic copper to thereby electrically connect the front and rear surfaces of the double-sided wiring glass substrate. The filling with the copper post is performed by first sealing, with copper, one opening part of the through-hole using an electrolytic plating method and then further plating copper from the one sealed opening part to the other opening part. As a result, the front and rear surfaces of the double-sided wiring glass substrate can be surely electrically connected as well as high thermal resistance of the whole double-sided wiring glass substrate can be secured.
1. A method for manufacturing a double-sided wiring glass substrate having electric wirings formed on the front and rear surfaces of a glass substrate, and a through-hole filled with a metal and penetrating the glass substrate, the respective electric wirings formed on the front and rear surfaces of the glass substrate being made electrically connective through the metal filling the through-hole, the method comprising the steps of:
a first step of forming the through-hole in the glass substrate;
a second step of forming an electrode layer having an opening part in an area corresponding to the through-hole on one surface of the glass substrate, and by an electrolytic plating method, sealing the opening part of the electrode layer with the metal at a first current density, and further by the electrolytic plating method, depositing the metal from the sealed opening part to an opening part of the through-hole of another surface of the glass substrate at a second current density lower than the first current density to fill the through-hole inside with the metal;
a third step of removing the electrode layer and the metal projecting from the through-hole on said another surface of the glass substrate from the glass substrate;
a fourth step of forming an adhesion-reinforcing layer on each of the front and rear surfaces of the glass substrate; and
a fifth step of forming the electric wirings on the adhesion-reinforcing layer formed on each of the front and rear surfaces of the glass substrate, the electric wirings being electrically connective through the metal filling the through-hole.
2. The method according to claim 1 , wherein the metal filling the through-hole is composed of any one or more of copper, nickel, gold, silver, chromium and aluminum.
3. The method according to claim 1 , wherein a photosensitive glass substrate is used as the glass substrate, and the first step comprises:
a step of exposing the glass substrate through a photomask to form a latent image on a part of the glass substrate in which the through-hole is formed;
a step of subjecting the glass substrate to thermal treatment to crystallize the exposed part; and
a step of removing by dissolving the crystallized part to form the through-hole in the glass substrate.
4. The method according to claim 1 , wherein the adhesion reinforcing layer has a three layer structure.
5. The method according to claim 1 , wherein the first current density is set to 1 to 5 A/dm 2 , and the second current density is set to 0.2 to 0.8 A/dm 2 .