THE DEVELOPMENT AND IMPLEMENTATION OF AN IMPROVED IMMERSION TIN PLATING PROCESS TIN-LEAD AND LEAD-FREE SOLDERING

摘要

Immersion tin plating as applied to a Printed Wiring Boardrnprovides a reliable and robust surface finish for componentrnassembly and in theory should be the best “drop in” tornreplace the HASL standard. The areas of concern presentedrnto an immersion tin formulation apply to the operation andrnmaintenance of the bath, the materials of board constructionrnand the assembly processes and materials.rnThe R&D group undertook a long-term study of a newlyrnformulated immersion tin process with the goal ofrnmeasuring and collecting extensive data per thernrequirements of the IPC-4554 Specification for ImmersionrnTin Plating for Printed Circuit Boards. Additionally therndeposit obtained was studied for the formation of thernintermetallic compounds for post plating and post assemblyrnconditions. For comparative and educational purposes thernIMC’s formed with ENIG as well as the Universal surfacernfinish ENEPIG and finally to the lesser known but veryrnpromising Pd over bare copper was included.