Wiring substrate and method for manufacturing wiring substrates

A wiring substrate comprising:

• a wiring layer;
• an outermost insulating layer laminated to the wiring layer;
• and
• a pad electrically connected to the wiring layer and exposed from a surface of the outermost insulating layer, wherein
• the pad consists essentially of:
• a first metal layer including a first surface, which is exposed from the surface of the outermost insulating layer, and a second surface, which is located opposite to the first surface;
• a second metal layer, which is laminated to the second surface of the first metal layer;
• and
• a third metal layer, which is formed between the second metal layer and the wiring layer, wherein
• the first metal layer is formed from a metal selected from gold and silver or from an alloy including at least one of gold and silver,
• the second metal layer is formed from palladium or a palladium alloy, and
• the third metal layer is formed from copper or a copper alloy.

A method for manufacturing a wiring substrate, the method comprising:

• forming a resist layer including an opening, which is shaped in conformance with a pad, on a main surface of a support body;
• forming a smooth surface on the main surface of the support body exposed from the opening of the resist layer;
• forming the pad by sequentially laminating a first metal layer, which is formed from a metal selected from gold and silver or from an alloy including at least one of gold and silver, and a second metal layer, which is formed from palladium or a palladium alloy, on the smooth surface;
• removing the resist layer;
• alternately laminating a predetermined number of insulating layers and a predetermined number of wiring layers on the main surface of the support body, wherein the pad is connected electrically to the wiring layers and exposed from a surface of the outermost one of the insulating layers;
• and
• removing the support body.