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In this paper, a user behavior based solder joint reliability modeling approach has been proposed to estimate the design and test requirements for the second level interconnect (SLI) reliability prediction. This approach uses a numerical tool to integrate solder joint creep damage during the actual use condition that was collected from a large user sample size. The resultant damage per time period was then input to the solder joint fatigue model to estimate equivalent damage to testing duration. The is a physics based approach and is expected to provide more accurate product life prediction and reliability performance demand for BGA package designs. IntroductionFor most electronic packaging failure mechanisms the user behavior plays a critical role in damage / degradation of the product. Currently, design requirements are based on a count of the number of times a system switches between power states and associated temperature ranges. A user survey is commonly used to collect user behavior data. The user survey result is then being translated to simple uniform temperature cycles based on a series of criteria (eg. power ON/OFF cycles/day counts). The translation is over conservative to account for the uncertainties in the user data.The first drawback of the current approach is the uncertainty of the user behavior. For electronic components, the heat generated by the silicon die is related to the work load. Furthermore, contemporary power saving features result in reduced temperatures when the component is in a standby or idle state. The "mini cycle" effect, the temperature fluctuation during normal use when the power is ON, should be carefully characterized. Currently, a simple assumption is that many small mini cycles are equal to several power cycles.The assumption may lead to conservative or unrealistic results based on the amplitude, duration and high or low temperature ranges in which the mini-cycle occurs.A significant drawback of current approach is not considering the temperature gradient of the component during use. Solder joint damage is caused by the thermal mismatch of the different materials in the packaging, so the temperature is the driving factor of the damage. The thermal cycle test condition uses a uniform temperature field for convenience and test efficiency. However, in the use condition, the silicon die is the heat source and the temperature gradient between the die-package and board will cause differential mechanical deformation, and a different solder joint damage distribution compared with the test condition. The empirically derived Norris-Landzburg (NL) equations cannot consider the effect of temperature gradients, transients or geometric factors; however, finite element modeling (FEM) can include the effect.

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