Lead-free paste for reflow soldering

摘要

A lead-free solder paste suitable for reflow soldering includes a plurality of different types of metal powder mixed with a flux. One of the metal powders is a Sn alloy powder. Another of the metal powders is selected from a Sn alloy powder, elemental Ag powder, elemental Cu powder, and elemental Sn powder. Each Sn alloy powder includes 0 - 8 mass % of Ag, 0 - 5 mass % of Cu, and at least 80 mass % of Sn. The plurality of metal powders have a composition when melted of 1 - 5 mass % Ag, 0.5 - 3 mass % Cu, and a remainder of Sn.