Simulation Investigations on Fluid/Structure Interaction in the Reflow Soldering Process of Board-Level BGA Packaging

Abstract

Abstract-The objective of the present study is to develop a Fluid/Structure Interaction model of a board-level Ball Grid Array (BGA) assembly for an infrared-convection reflow oven. The infrared-convection reflow oven is modeled in Computational Fluid Dynamic (CFD) software while the structural heating BGA package simulation is done using Finite Element Method (FEM) software. Both software applications are coupled bidirectional using the Multi-physics Code Coupling Interface (MpCCI). The simulation thermal profile is compared with the experiment thermal profile, and they were found to be in good conformity. The simulated flow fields show that the convection mode in an infrared-convection reflow oven played minor effect on heat transfer to the printed circuit board (PCB). The dominant heat transfer mode in an infrared-convection reflow oven is the radiation mode from a quartz heating tube. From the simulation results, the PCB near the edges or corners tended to heat up first at preheating, soaking and reflow stages. The PCB and component experience larges temperature difference in preheating stage. This situation runs the risk of an excessive board warpage. In addition, the maximum von-Mises stress is trapped in the interfaces between solder joint and die, which intend to form the nucleation of initial solder joint crack. This guideline is very useful for the accurate control of temperature and thermal stress distributions within components and PCB, which is one of major requirements to achieve high reliability of electronic assemblies.Index Terms-Ball grid array assembly, infrared-convection reflow oven, computational fluid dynamic, finite element method. I. INTRODUCTIONReflow soldering process has been affected by miniaturization of electronic packages and complicated thermal-mechanical design of a printed circuit board (PCB) assembly. Additional challenge is presented with environmental concerns propelling a rising trend toward lead-free soldering. A lead-free solder requires a narrower range of flow temperatures and workable melt compared with a lead-based solder. Using an inadequate reflow profile may not only result in a high level of thermal stress in the package, but may also result in excessive PCB warpage [1]. Those defects can then result in significant reliability issues in the electronic industry. In recent years, a simulation tool for the reflow soldering process greatly helps the electronic manufacturing industry [1]. Therefore, a prediction of the thermal response of the soldering process is crucial for initial parameter design. The popular thermal response analysis at the package level is based on the finite-element method (FEM). Shen et al. [2] and Inoue and Koyanagawa [3] built the FEM model to obtain the temperature distribution of a ball grid array (BGA) package for the reflow process. The average heat-transfer coefficient (h avg ) was calculated using experimental equations for multiple impinging jets. However, the experimental results obtained by Illé s [4], [5] showed that the heat transfe...

Effects of the Solder Phase Transformation on the Optimization of Reflow Soldering Parameters and Temperature Profiles

“…e unexpected results indicated that the convection mode in the infrared convection oven had little effect on the heat transfer of the PCB. In other words, the outcomes of natural convection and forced convection were similar in an infrared-convection reflow oven [10]. Due to the huge temperature changes in the soldering process, the thermal conductivity and convection coefficients are inconstant.…”

“…In fact, the mainstream was the finiteelement method (FEM) with advantages that there is no need to consider the complex differential equations and unintelligible physical concepts. While there was a fact that its accuracy was incomparable, the computation was particularly enormous [5,[9][10][11][12][13]. e surface temperature of the motherboard on flexible printed circuit boards was predicted using the simulation software ANSYS, though the reliability of the results still needs further experimental verification [14].…”

“…e surface temperature of the motherboard on flexible printed circuit boards was predicted using the simulation software ANSYS, though the reliability of the results still needs further experimental verification [14]. By applying simulation software, the computational fluid dynamics (CFD) models of reflow soldering were also tried [10][11][12]15]. On the other hand, as the reflow soldering model becomes more accurate, on the basis of the temperature profile, the evaluation of soldering quality and optimization of relevant parameters, such as the heat transfer coefficient, heat flow, and reflux cooling time, have gradually been developed [5,16].…”

Influence of copper pillar bump structure on flip chip packaging during reflow soldering: a numerical approach

“…Recent work by Lau and Abdullah (2013) has outlined a methodology for the thermal modelling of a BGA assembly during forced convection reflow soldering by using FSI method. Their work provided a new guideline for thermal coupling method and is useful for the accurate control of temperature distribution within PCB assembly.…”

Investigations of Infrared Desktop Reflow Oven with FPCB Substrate during Reflow Soldering Process

“…Based on the diversity of the findings, tthe DO model was chosen to be compared with the experimental data throughout the study. Lau et al [15] claimed that the DO model was suitable for the case study with a localized heat source, such as using the IR. In regard to the numerical approach, the DO also poses the advantages of moderate computational cost in tetrahedral angular discretization with modest use of memory.…”