Numerical Study On Impact Failure Of Electronic Packaging Component

The reliability of electronic device caused by shock/drop is always one of several important issues in the electronic packaging research. With the miniaturization of electronic products, high density integration, and lead-free manufacture, the reliability problem of solder joint structure also becomes more and more serious. Currently, the component-level solder ball impact test as well as board-level drop test has been widely used for studies of solder joint reliability. In this paper, failures caused by shock/drop have been studied using ABAQUS by simulations of the component-level solder ball impact test as well as board-level drop test. Compared with the experimental results, the dynamic response and failure mechanism of solder joint under impact load have been researched. The main contents are summarized as follows.1. In order to better simulate the mixed-mode failure, an improved3D exponential cohesive zone model has been proposed. User subroutines (e.g. VUEL and VUSDFLD) in ABAQUS have been developed for its numerical implementation. The numerical verification showed that the proposed exponential cohesive zone model is able to accurately simulate the interfacial delamination.2. Aimed at the impact test on component-level solder ball, failure simulations have been carried out for solder joints under various transient impact loads (including shearing, pulling and peeling). In these simulations, the progressive damage model, by considering the strain rate effect of solder material, is employed to simulate solder joint failure. At the same time, the cohesive zone model proposed in this paper is utilized to simulate the interfacial failure between solder ball and copper pad. By various simulations, the influence on the failure modes (including IMC strength, impact rate and impact angle, etc.) has been explored, and the reason for solder joint failure was disclosed. The comparisons with experimental results showed that the proposed model and method can effectively simulate the solder joint failure of electronic package under impact loading.3. With regard to the board-level drop test, a three-dimensional finite element model has been constructed according to JEDEC specimen standard, and the input-G method has been used to simulate the dynamic drop failure of solder joints in electronic package component. In this paper, a new drop test simulation method has been presented, in which the cohesive zone elements are buried along solder joint interfaces to consider IMC failure. This method can help us explore the solder joint failure more effectively. Through theoretical analysis, finite element simulation and comparison with experimental results, the law of the solder joint failure was revealed and the reason for failure was clarified. Besides, the effects of solder joint height and diameter on the reliability of package components were further investigated.4. Several more professional applications of cohesion zone model in the failure simulation of electronic package structure have been further explored. For example, strain rate dependent and triaxial stress dependent cohesive zone models are proposed and implemented, respectively. Several numerical verifications confirmed the validity of the newly-developed models. Due to the lack of experimental data, the present work is not allowed directly to compare with the experimental results. However, this work has an important significance for us to carry out a further research on failure simulation of solder joints in the future.