Ball shear versus ball pull test methods for evaluating interfacial failures in area array packages

In this investigation, a ball pull (tensile) test is investigated as an alternative to the ball shear test for evaluating the solder joint integrity of area array packages. The relative effectiveness of the pull and shear methods is compared using BGA packages with documented susceptibility to brittle interfacial failure during accelerated temperature cycling tests or isothermal aging. Accelerated temperature cycling is used typically to measure long term solder joint attachment reliability in various use environments and isothermal aging is used to measure susceptibility to degradation following high temperature storage. The shear and pull tests are conducted on packages in the as received condition and after thermal preconditioning. Metallographic failure analysis and scanning electron microscopy with energy dispersive X-ray analyses are used to characterize the solder joints and fracture modes. The ball shear and ball pull results are compared and discussed in terms of the ability to predict susceptibility to interfacial failures in area array packages.