SMTA International Conference Proceedings


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

Author: Hank Lajoie
Company: OMG Electronic Chemicals, Inc.
Date Published: 10/4/2009   Conference: SMTA International


Abstract: Immersion tin plating as applied to a Printed Wiring Board provides a reliable and robust surface finish for component assembly and in theory should be the best “drop in” to replace the HASL standard. The areas of concern presented to an immersion tin formulation apply to the operation and maintenance of the bath, the materials of board construction and the assembly processes and materials.

The R&D group undertook a long-term study of a newly formulated immersion tin process with the goal of measuring and collecting extensive data per the requirements of the IPC-4554 Specification for Immersion Tin Plating for Printed Circuit Boards. Additionally the deposit obtained was studied for the formation of the intermetallic compounds for post plating and post assembly conditions. For comparative and educational purposes the IMC’s formed with ENIG as well as the Universal surface finish ENEPIG and finally to the lesser known but very promising Pd over bare copper was included.

Key words: Immersion tin, intermetallic compounds (IMC), e-phase, n-phase, Focused Ion Beam (FIB), horizontal processing, wetting balance, spread test.



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