Orthogonal Experiment for Analyzing the Impact of Thermal Stress on the Reliability of an EMC Package

In recent years, plastic packaging has become the main form of electronic packaging technology due to its low cost, miniaturization, and simple producing process. Epoxy molding compound (EMC) are widely used in electronic packaging as encapsulants of electronic devices. However, in the actual service environment, due to the material properties of epoxy molding compounds, there are many factors cause the package structure failure. In this paper, we design the orthogonal experiment to systematically investigate the impact of thermal stress on the reliability of a molded underfill (MUF) FCBGA (flip-chip ball grid array) structure by using the finite element analysis. In the orthogonal experiment, the F test is used to estimate whether the experiment is reliable, and the T test is used to select the most important factors from the samples. The statistical analysis indicates that the coefficient of thermal expansion (CTE) and modulus of EMC have the significant influence on the thermal stress of the EMC package, and static max thermal stress is at the interface between the chip and EMC. In addition, we find that the node of the static max stress and the one of the max displacement are different.