Base material selection for reliable lead-free processing

Purpose - To demonstrate a method of selecting base materials for lead-free processing based on the kinetics of decomposition. Design/methodology/approach - The paper describes the calculation of Arrhenius kinetic parameters from common "time to delamination" data (T(260)). Delamination is correlated to a certain conversion into the decomposition reaction. With both of these parameters, various soldering scenarios are analysed. Findings - The findings highlight the fact that conventional FR-4 materials are only good for a few reflow cycles. A higher number of reflow cycles can only be fulfilled with RoHS compliant base materials. However, rework and repair may even shift those more thermally resiliant materials over the limit. The peak temperatures are over proportionally responsible for delamination failures and need to be controlled carefully. Originality/value - The value of the paper lies in its ability to provide guidance on the selection of base materials to comply with various soldering processes. A model has been developed that is able to predict failure limit for a given base material and a given process.