Lead-Free Solder Ball

A method of mounting a module substrate for a BGA or a CSP to a printed circuit board, comprising:

• placing a solder ball having an alloy composition on each of a plurality of electrodes provided on the module substrate for the BGA or CSP;
• heating the solder balls to form a solder bump on each of the electrodes;
• preparing the printed circuit board by applying a solder paste onto each of a plurality of electrodes provided on the printed circuit board;
• mounting the module substrate onto the printed circuit board by contacting the solder bumps with the solder paste, wherein the solder bumps are facing downwards with respect to the printed circuit board during the mounting step;
• and
• heating the solder bumps and the solder paste to solder the solder bumps to the electrodes of the printed circuit board,
• wherein the alloy composition of the solder ball consists of:
• 1.6-2.9 mass % of Ag;
• 0.7-0.8 mass % of Cu;
• 0.05-0.08 mass % of Ni;
• optionally at least one element selected from Fe, Co, and Pt in a total amount of 0.003-0.1 mass % or optionally at least one element selected from Bi, In, Sb, P, and Ge in a total amount of 0.003-0.1 mass %;
• and
• a remainder of Sn.