Estimation of yield through component placement accuracy in surface mount PWB assembly

Abstract The effectiveness of the placement process in ultra fine pitch Printed Wiring Board (PWB) assembly is influenced primarily by the accuracy of the PWBs, the dimensional stability of the Surface Mount Components (SMCs), and the capability of the pick and place machine used. The objective of this research was to understand how variations in the functional parameters of the PWBs, SMCs and placement affects the objective function of lead to pad coverage. A system model was formulated to quantitatively determine the impact of each set of inputs on this objective function. Computer based simulation software was designed and developed to estimate the Lead To Pad Coverage (LTPC). It provides a reasonable estimate of the distribution of the LTPC based on board, SMC, and the placement machine parameters.