Designing for zero defect manufacturability using statistical process control techniques

The authors describe an analytical method that utilizes statistical process control techniques to enable a manufacturer of electronic components and/or systems to enhance the quality of the finished product by measuring and controlling the defect levels (and yields) at the various steps of the overall manufacturing operation. The method, which uses a simple approximation for the probability density function for defective material produced during a given manufacturing process, makes it possible to quantify and predict the number of defects that will be produced once specification limits are established for reliable operation of the system. Depending on the complexity of the final product and the number of manufacturing operations involved, the method allows the manufacturer to allocate the maximum number of allowable defect levels to the various critical stages within the manufacturing cycle so as to ensure a preassigned outgoing product quality level. This approach allows the attainment of higher quality of levels than do conventional quality control methods. The results obtained are shown to be supported by the available data