Authors: C E Ho W H Wu L H Hsu C S Lin
Publish Date: 2011/08/13
Volume: 41, Issue: 1, Pages: 11-21
Abstract
The effect of PdP thickness on the solid–solid reaction between Sn3Ag05Cu and Au/PdP/NiP at 180°C was investigated in this study The reaction was conducted after reflow thereby removing the Au/Pd finish before the solidstate reaction The reaction products included CuNi6Sn5 Ni2SnP and Ni3P and their growth strongly depended on the PdP thickness especially for the former phases ie CuNi6Sn5 and Ni2SnP As the PdP thickness increased from 0 μm to 01 μm to 022 μm the CuNi6Sn5 exhibited a needlelike dense layer chunklike morphology and discontinuous morphology respectively The alternative phase Ni2SnP behaved in a manner opposite to that of CuNi6Sn5 growing with a discontinuous morphology to a dense layer with increasing PdP thickness However this strong dependence disappeared when the solder joints were subsequently subjected to solidstate aging The CuNi6Sn5 and Ni2SnP both became layered structures for all cases examined A highspeed ball shear HSBS test was conducted to quantify the mechanical response of the interfacial microstructures The HSBS test results showed that any initial difference in shear strength caused by the various PdP thicknesses could be reduced after the solidstate aging which is consistent with the microstructural evolution observed The mechanical strength of the solder joints was decreased due to the presence of a biintermetallic structure of CuNi6Sn5/Ni2SnP at the interface Detailed analysis of the growth of CuNi6Sn5 and Ni2SnP is also provided
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