Patent ID: 8394225

Claim:
A method of manufacturing a wiring substrate, comprising: preparing two stacked bodies, each having a first carrier, a first insulating layer, and a metal layer, the first carrier having a first carrier plate, a first peeling layer and a first metallic foil provided on one surface side of the first carrier plate via the first peeling layer, the metal layer being thicker than the first metallic foil of the first carrier and being provided on a metallic foil side of the first carrier via the first insulating layer; forming a joined body by jointing the carrier plates of each of said two stacked bodies to a joining layer such that the two stacked bodies are joined via the joining layer; forming first conductor patterns by patterning the metal layers positioned on both sides of the joined body respectively; providing second carriers, each of which has a second carrier plate, a second peeling layer, and a second metallic foil provided on one surface side of the second carrier plate via the second peeling layer, to the first conductor patterns formed on both sides of the joined body respectively via second insulating layers such that each of the first conductor patterns is opposed to the second metallic foil of one of the second carriers via one of the second insulating layers, the metal layer being thicker than the second metallic foil of the second carrier; forming two substrates, each of which has a first side surface defined by one first metallic foil and a second side surface defined by one second metallic foil, by peeling the first carrier plates of the first carriers and the second carrier plates of the second carriers from the respective first and second peeling layers of the first and second carriers; and forming second conductor patterns which are connected electrically to the first conductor patterns via vias that pass through the first and second insulating layers respectively, from the first and second metallic foils formed on the first and second surface sides of the substrate; and wherein the joined body is formed after the two stacked bodies are prepared, the first conductor patterns are formed after the joined body is formed, the second carriers are provided after the first conductor patterns are formed, the two substrates are formed after the second carriers are provided, and the second conductor patterns are formed after the two substrates are formed.