The Influence of Intermetallic Compounds on High Speed Shear Testing with a Specific Interest in Electroless Palladium and Autocatalytic Gold

摘要

Increasing I/O counts have led to ever decreasing cross sectional contact areas or, by default, an increase in solder performance expectations. A recognized measure of solder joint integrity is gained through High Speed Shear testing. (HSS). This article will statistically evaluate the solderability of the dominant final finishes with reference to some real life variables. The only skew is that only lead free solder balls have been used in this exercise to simulate production. The following final finishes were selected: 1. Immersion tin (i-Sn). 2. Organic Surface Protection (OSP). 3. Electroless Nickel/Immersion Gold (ENIG). 4. Electroless Nickel/Electroless Palladium and Immersion Gold (ENEPIG). 5. Electroless Palladium/Semi Autocatalytic Gold (EPAG). This evaluation will endeavor to relate HSS performance, specifically the total energy, to the physical characteristics of the resultant solder joint associated with final finishes selected. In the field, there are assertions that the IMC is a good indicator of the solder joint integrity. However this is usually as far as this particular statement is taken. A key question that is still outstanding is what particular attribute of the IMC is important for Solder Joint Reliability, (SJR). The shape, size and composition of the IMC are often cited as reliable tools for predicting SJR. To assess whether such indicators may be valid, this study will couple high resolution microscopy with HSS testing to artificially induce mechanical failure.