Transient thermal analysis of an ACF package assembly process

Transient thermal simulation was performed to analyze thermal response of the assembly process for a package using anisotropic conductive film (ACF). The main purpose of the study is to simulate the actual assembly and manufacturing process, in order to provide a first-hand approximation and insight of the thermal behavior of the package and ACF film during the process. Two assembly processes were modeled: a simplified process where the package was fixed at two different temperatures during assembly, and a detailed process where the package experienced a ramping heating process, followed by a constant temperature curing process. A full convection-conduction case was conducted first. The results indicate a weak hydrodynamic field and radiation effects, hence for computational purposes (reduced CPU time), it was decided to model the process using a conduction-only investigation. Results from the detailed process modeling indicated that during the initial ramping, within 0.02 s, the die and nozzle head experienced a small temperature drop due to the cooling effect of the ACF material and substrate. The ACF material also displayed a steep increase in temperature after contacting the die, followed by a short decay, then ramped up again. At the end of the 10-s ramping process, the ACF reached a temperature of almost 203°C, while the die was at 206°C. During the 5 s of curing, all parts reached steady state in less than 2 s