Lead-free solder used for connecting electronic parts on organic substrate and electronic products made using same

摘要

Provided is a lead-free solder for connecting LSI and parts on organic substrates, which can provide soldering at a maximum temperature of 220 DEG -230 DEG C. and which has a sufficient reliability in mechanical strength even at a high temperature of 150 DEG C. Also provided are electronic products prepared using this lead-free solder. The lead-free solder has a solder composition including 3-5% Zn and 10-23% Bi, the balance being Sn. Preferably, the solder composition is a composition (Sn, Zn, Bi) surrounded by lines connecting A and B, B and C and C and A, where A is (85, 5, 10 ), B is (72, 5, 23) and C is (76, 3, 21), of a ternary diagram having pure Sn, pure Zn and pure Bi at the vertices of an equilateral triangle. Through use of this solder, it is possible to solder parts, etc. on conventionally employed organic substrates at reflow temperatures equivalent to those for conventional Pb-Sn eutectic solders. The solder does not damage the environment, can be stably supplied and is low in cost.