Reliability of 0.4 mm pitch, 256-pin plastic quad flat pack no-clean and water-clean solder joints

Abstract
The reliability of 0.4 mm pitch, 28 mm body size, 256-Pin Plastic Quad Flat Pack (QFP) no-clean and water-clean solder joints has been studied by temperature cycling and analytical analysis. The temperature cycling test was run non-stop for more than 6 months, and the results have been presented as a Weibull distribution. A unique temperature cycling profile has been developed based on the calculated lead stiffness, elastic and creep strains in the solder joint, and solder data. Also, the thermal fatigue life of the solder joints has been estimated and correlated with experimental results. Furthermore, a failure analysis of the solder joints has been performed using Scanning Electron Microscopy (SEM). Finally, a quantitative comparison between the no-clean and water-clean QFP solder joints has been presented.

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