Critical parameters for achieving optimum reflow profiles for plastic package preconditioning

Temperature profiles of surface mount components progressing through convection and infrared reflow systems are studied with respect to package size, inter-component spacing, and loading density. For constant forcing temperature, T/sub max/ varies inversely with component mass. A minimum component spacing required to minimize T/sub max/ variation is established. Package delamination and cracking are shown to depend primarily on T/sub max/.