3-D Modeling and Characterization for Die Attach Process

A new 3-D model for the die attach (DA) process is established and validated in this paper. With this model, the fluid flow characteristics of the DA process can be predicted accurately. Dynamic mesh and interface tracking method were adopted in the modeling to study the compression motion and the front of DA. A force driven model was conducted for the parametric studies of different bonding forces. The model for the DA process was validated by the four materials, AP1, CA1, CA4, and DM60 in the optimized condition. Bond line thickness can be predicted by the simulation with ~20% accuracy. The simulation results show that the viscosity is one of the key properties, which has a significant effect on the required bonding force, bonding time, and DA contamination on the die top. Complete filling and DA contamination on the die top are two important standards to evaluate the good bonding force range in fluid dynamic analysis. Stress analysis illuminates that a fillet area is very critical and experiences highest stress during the reflow process.