A combined environment testing was conducted for the Joint Council on Aging Aircraft/Joint Group on Pollution Prevention Lead free Solder project. The purpose of the project was to validate and demonstrate lead free solders as potential replacements for conventional tin-lead solders used on circuit card assemblies against the requirements of the aerospace and military electronics community. The solder alloys tested include: Sn3.9Ag0.6Cu, Sn3.4Ag1.0Cu3.3Bi, Sn0.7Cu0.05Ni and Sn37Pb. These solder alloys were used to assemble various components on three different printed wiring board test vehicles: manufactured, rework and hybrid. The test vehicles were subjected to a combined environments test consisting of thermal cycling from -55 to 125 degrees Celsius at a ramp rate of 20 degrees Celsius per minute, dwell at the temperature extremes for 15 minutes and pseudorandom vibration of 10 g_(rms) for the last 10 minutes of the dwell periods. After every 50 cycles, the vibration level was increased by 5 g_(rms) until a maximum of 55 g_(rms) was reached. The test vehicles were electrically monitored using event detectors. The solder joint failure data of a given component type, component finish and solder alloy were evaluated using Weibull analysis. The reliability of the lead free solder alloys was compared to the baseline tin-lead (Sn37Pb) solder alloy.
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