Cross-scale finite element analysis of PCBA thermal cycling based on manufacturing history for more accurate fatigue life prediction of solder joints

Printed Circuit Board Assemblies (PCBA) are crucial components of integrated circuit products. To address the issue of solder joint failure in PCBA under thermal cycling conditions, this study proposes a multiscale modeling approach to assess the warpage of the Printed Circuit Board (PCB) and the thermal fatigue life of solder joints during the PCBA working process. Firstly, a PCBA model incorporating the PCB, substrate, chip, Epoxy Molding Compound (EMC), and solder joints was established. The equivalent thermal-mechanical properties of the Conductive Layers (CDLs) in the PCB are calculated using a mesoscopic finite element approach to capture its complex structural characteristics. Finite Element Analysis (FEA) was conducted on the reflow soldering and thermal cycling processes of the PCBA to systematically investigate the effects of temperature variations during thermal cycling and residual stress from the manufacturing process on the fatigue life of solder joints. The results indicate that during the thermal cycling process, the complex deformation of the solder joints caused by the inconsistent deformation of the PCB and substrate as well as the accumulated inelastic strain of the solder joints lead to solder joint failures, and the dangerous solder joint is concentrated at the edges of the solder joint array. The temperature range significantly influenced the fatigue life of solder joints because of the thermal fatigue life of the solder joints decreased as the temperature range increased. The presence of residual stress during manufacturing reduces the fatigue life of solder joints, thus emphasizing the need to optimize the reflow process design to reduce residual stress in solder joints. The cross-scale simulation method developed in this study enables more accurate prediction of the thermal fatigue life of solder joints, thereby facilitating reliability studies and optimized designs of integrated circuit products.