Fatigue Life Prediction Model for LEDs On Metal Core Printed Circuit Boards (MCPCBs) with Pb-Free Solder Alloys
Authors: Maxim Serebreni, Nathan Blattau, Craig Hillman, Ravi Bhatkal, Gyan Dutt, Ranjit Pandher Company: DfR Solutions, Alpha Assembly Date Published: 9/17/2017
Abstract: There is currently no applicable model for solder fatigue of components attached to Metal Core Printed Circuit Boards (MCPCBs). The increased implementation of MCPCBs for LED lighting application has introduced large variability in material properties of the base substrate material, dielectric material and LED package materials. The contribution of the exact combination of MCPCB material properties and package type on the solder interconnects fatigue under cyclic thermal loads cannot be analyzed currently without complex numerical simulations. This study proposes an improved semi-analytical model to predict the fatigue life of LED solder interconnects under fluctuating thermal conditions. Strain energy calculations were performed by incorporating the effective interfacial stiffness and material properties of each layer in the LED and MCPCB assembly. In addition, SAC305 and a High Creep Resistant Solder Alloy (CRA) were assessed in combination of different dielectric materials. CRA demonstrated better fatigue performance compared to conventional SAC305 solder. The semi-analytical model enables to determine trends in fatigue life predictions of solder interconnects due to changes in MCPCB and solder alloy materials and geometry. This study has shown the applicability of the semi-analytical model to LEDs assembled on MCPCB using conventional and high reliability solder alloys.
LED solder joint reliability, MCPCB, Fatigue life prediction model, dielectric, creep resistant alloy