A Comprehensive Failure Analysis and A Study on Reliability for BGA Solder Joints Crack of DDR Modules

Nowadays, Double Data Rate (DDR) modules are generally applied in the electronic products. In this paper, the key failure modes for solder joints of DDR module are introduced. For many kinds of finishes, the typical intermetallic compounds (IMCs) found in solder joints are Cu6Sn5, and IMCs like Cu-Ni-Sn are formed at Ni surfaces. With the typical BGA structure, there are 8 possible failure locations where the fracture would occur when the complex external conditions apply to the solder joints. We study the mechanisms explaining how and why the failures happen during the productions' design, manufacture and application. In order to prevent these failure modes, four reliability test methods of solder joints are suggested which based on the characteristics of solder joints. Consider the cost of the reliability test, we use our presented equivalent anisotropic thermal-structure coupling model to simulate the stress of solder joints. The equivalent model is calculated based on equivalent inclusion method and the uniform distribution method, and the model not only considers the physical parameters and the material properties of the DDR memory, but also considers the thermal coupling. By using the reliability test method and the thermal-structure coupling model in combination, the solder joints reliability of Double Data Rate memory modules can be optimized in the design stage.