SOLDERING METHOD FOR SUPPRESSING FILLET LIFTING

摘要

PROBLEM TO BE SOLVED: To suppress fillet lifting which stripps solder from a land by heating the lead of a part directly or indirectly when a part having a lead is mounted on a printed wiring board thereby retarding solidification of solder in the vicinity of the lead. SOLUTION: A part having a lead is mounted by soldering to the through hole 12 of a printed wiring board 10 using a connector 20. The solder 30 is composed of an Sn-Bi alloy having wt.% of 93:3 and has a melting point in the range of 219-230 deg.C. Soldering is carried out by supplying hot air to the lead 22 to form a molten solder fillet at a solder joint and further supplying hot air for about 10 sec until the solder 30 is solidified thus retarding solidification thereof. Consequently, fillet lifting which stripps solder from a land canbe suppressed.