The purpose of this paper is to develop a thermal coupling method of a ball grid array (BGA) assembly during a forced convection reflow soldering process.
The reflow oven was modeled in computational fluid dynamic (CFD) software (FLUENT 6.3.26) while the structural heating BGA package simulation was done using finite element method (FEM) software (ABAQUS 6.9). Both software applications were coupled bi‐directionally using the code coupling software MpCCI.
The convective heat transfer coefficient (h) simulated during the reflow process showed a sufficient view of the changing h in the BGA assembly of each reflow oven. The solder joints were found to experience phase change from solid to liquid during heating and liquid to solid during cooling. These phase changes were present at the melting temperature of the solder joint. The effect of the phase transition point was to cause a large range of temperature difference within the BGA assembly. This situation runs the risk of a skewing defect of components. The simulation results were compared with the experimental results and found to be in good conformity. In addition, the maximum thermal stress from simulation results was trapped in the interfaces between the solder joints and substrate, which tended to form the nucleation of initial crack.
The current study provides a methodology for designing a thermal profile for reflow soldering production.
The findings provide new guidelines for the thermal coupling method. This guideline is very useful for the accurate control of temperature distributions within components and printed circuit boards, which is one of major requirements for achieving high reliability in electronic assemblies.
