Printed wiring board and method for manufacturing the same

A method for manufacturing a printed wiring board, comprising:

• forming an outermost resin insulating layer;
• forming a conductor layer on the outermost resin insulating layer;
• forming a solder resist layer on the outermost resin insulating layer such that the solder resist layer covers the conductor layer;
• forming an opening in the solder resist layer such that the opening exposes a portion of the conductor layer;
• forming a Ni layer on a surface of the portion of the conductor layer such that the Ni layer is positioned in the opening formed in the solder resist layer;
• forming a Pd layer on a surface of the Ni layer such that the Pd layer is positioned in the opening formed in the solder resist layer;
• and
• forming a solder bump layer on a surface of an alloy layer such that the solder bump layer comprises an Sn-Pd alloy having a Pd content of 0.5 at% or less,
• wherein the forming the solder bump layer includes forming a solder paste layer on a composite layer comprising the Ni layer and the Pd layer and reflowing the solder paste layer formed on the composite layer such that Pd in the Pd layer diffuses into the solder paste layer and that the solder bump layer comprising the Sn-Pd alloy having the Pd content of 0.5 at% or less is formed on the surface of the alloy layer.