Experimental analysis of a protective wafer coating process for the die preparation

The application of coating process is a conventional part of the photolithography which is widely used in the IC fabrication and the manufacturing of micro-electro-mechanical systems (MEMS). The uniform experimental design method combined with regression analysis is applied to investigate the protective coating process aimed to protect the die from silicon contaminations in the die preparation phase of the IC assembly. Ten experimental runs based on the randomization principle and the uniform design tables are executed. The weight of the flux coated on the substitute coupon is measured and adopted as the quality target of the coating process and four control parameters, the scale of micrometer valve, the flux pressure, the dispenser velocity and the atomizing pressure are selected as experimental factors in this study. A significant regression model is obtained based on the experimental data and the scale of micrometer valve, the flux pressure and the dispenser velocity are found to be significant factors in the protective coating process. Such model could be used as the mathematical prediction of the flux weight and help to improve the coating velocity without violating the weight constraint required for its protection purpose.