Predicting plated-through-hole reliability in high temperature manufacturing processes

Plated-through-holes (PTH) represent a sensitive interconnect structure in a printed wiring board (PWB) that can be adversely affected by both manufacturing and field-use load cycles. A PTH/PWB model has been developed using the finite-element method (FEM) and the Manson-Coffin equation. The author discusses the model development and its application in an exhaustive test program where coupons of two laminate materials (FR4 and PI), four drilled hole sizes (0.0135 in, 0.0160 in, 0.023 in, and 0.043 in), and four nominal plating thicknesses (0.0005 in, 0.0010 in, 0.0015 in, and 0.0020 in) were tested. Based on measured ductility from the IPC Copper Foil Round-Robin Study, good agreement is obtained between the measured and predicted PTH reliability. A sensitivity analysis in which the model is used to predict the reliability of a PTH/PWB structure is presented. The variables examined are laminate T_g and TCE, drilled hole and pad diameter, minimum plating thickness, and plating nonuniformity