SOLDER PASTE COMPOSITION, PRODUCTION OF PRINTED CIRCUIT BOARD HAVING SOLDER PAD, AND PRODUCTION OF ELECTRONIC PART PACKAGE CIRCUIT BOARD

摘要

PROBLEM TO BE SOLVED: To improve packaging yield of a part by not generating solder bridge to a pad having narrow pitch of a printed circuit board mounting a narrow pitch part and forming a solder coated layer having uniform film thickness and composition. SOLUTION: The solder paste composition is a mixture of solder alloy powders having plural compositions different in melting temp. range and an eutectic temp. of 183±10 deg.C or its neighborhood temp. at fusing, further containing a ratio of flux in the total of the solder powder and flux of 10-50wt.%. It is the printed circuit board having a pad and the production method with using the composition. By this method, the productivity is good and cost is reduced.