Patent ID: 7781323

Claim:
In a semiconductor device manufacturing method which includes mounting a semiconductor element on a substrate, the mounting comprising: supplying solder paste including Au-Sn series solder particles and flux onto a Ni film formed on a surface of a wiring provided on the substrate, putting the semiconductor element having a bonding electrode on the solder paste, the bonding electrode comprising a surface on which a Ni film is formed, the Ni film formed on the surface of the bonding electrode being coated with a film of one of an Sn alloy or Sn, melting the Ni film formed on the surface of the wiring, the Ni film formed on the surface of the bonding electrode, the Au-Sn series solder particles and the film of one of the Sn alloy and Sn at a reflow temperature of 280-320 deg. C. for 5 seconds or less, solidifying the melted Ni films, the melted Au-Sn series solder particles, and the melted film of one of the Sn alloy and Sn to form a plurality of alloy layers including an alloy layer which is formed from the Ni film formed on the surface of the bonding electrode and the film of one of the Sn alloy and Sn, or an alloy layer which is formed from the Ni film formed on the surface of the bonding electrode, the Au-Sn series solder particles, and the film of one of the Sn alloy and Sn, said plurality of alloy layers serving as a bonding portion which bonds the substrate to the semiconductor element, and cleaning the bonding portion to eliminate the flux.