Numerical Analysis of Lead Free Solder Ball During Reflow Process

Abstract

Reflow soldering is one of the most significant factors in development of surface mount technology (SMT), especially toward the lead-free and miniaturization of the advanced ball grid array (BGA) package. Moreover, an inadequate reflow profile causes the reliability issues in manufacturing assembly process. This numerical method comprised the computational fluid modeling of the internal flow in the reflow oven were coupled with the structural heating modeling of the BGA assembly. The concept and idea is to develop a thermal analysis of a Ball Grid Array (BGA) assembly during a forced convection reflow soldering process in 3D simulation modeling using computational fluid dynamic (CFD) software (ANSYS Fluent 14.5) and then transfer to ANSYS Steady State-Thermal 14.5 to import data from ANSYS Fluent 14.5. Structural heating BGA package simulation was done using finite element method (FEM) software (ANSYS Static Structural 14.5) All software application were coupled using the code coupling software ANSYS Workbench 14.5. Reflow process is one of the important assembly steps for electronics packaging. An inadequate reflow thermal profile will also cause several soldering defects. Thus, the understandings of the reflow process are significant for engineer to control the quality and reliability of the assembled part. The current study provides a methodology for designing a thermal profile for reflow soldering production. Reflow temperature profile of a single oven was utilized in the simulation modeling to model the actual condition of process. During the reflow soldering process, the hot air distribution of the oven and temperature profile of the BGA, printed circuit board (PCB) and Substrate were visualized through the post processing steps. The temperature variations at different reflow times were obtained in the current study. The simulation results revealed that temperature distribution on the package able to sustain the high temperature profile. The simulation modeling approach is expected to enhance the understandings of the reflow process for the engineers in the electronics industry.