Intermetallic compounds (IMCs) are generally considered a bad thing in solder joints, though this is not always the case. Excessive IMCs in solder joints are a bad thing since they significantly alter both the composition and the mechanical performance of the solder joint. Interfacial IMC layers can be an indication of the quality of the solder joint and the lack of them would indicate a solder process or possibly a material problem.
The intermetallic compounds that have been most important in our work performing microstructural evaluations on solder joints are described in this paper.
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