NUMERICAL MODELING AND ANALYSIS OF MICROBUMP PITCH EFFECT IN 3D IC PACKAGE WITH TSV DURING MOLDED UNDERFILL (MUF)

In this paper, the microbump pitch effect in molded underfill (MUF) is analyzed in the 3D integrated circuit (IC) package with a through-silicon via by numerical modeling. The current trend of decreasing the microbump pitch could make the MUF process more difficult. However, no detailed study on the particular area, particularly on the MUF process, has been conducted so far. Therefore, this paper could be a good reference by providing detailed information on the process. In our analysis, FLUENT 6.3.26 is used to predict the MUF flow front advancement under the effect of a different microbump pitch. The strong ability of FLUENT to predict flow front advancement was validated by the experimental results in the literature. Based on the analysis, the effect of the microbump pitch has significant implications on the filling rate, velocity profile, epoxy molding compound conversion rate, pressure distribution, and air void entrapment level. From the numerical analysis, a smaller microbump pitch is inferior in terms of the filling rate and air void entrapment level. The data and the analysis provide fundamental knowledge in understanding the effect of the microbump pitch on the MUF process.