Defective Reduction on Dent Defects in Flexible Printed Circuits Manufacturing Process

Abstract

This research presents methods to reduce defectives due to dent defects in flexible printed circuits manufacturing process. The DMAIC phases of Six Sigma quality improvement approach were applied to solve the problem. It was found that the variables that statistically affect the dent problem were 1) method to polish stainless steel plate, 2) method to store stainless steel plate, 3) method to clean stainless steel plate, 4) fisheyes/ foreign matters in the TPX release film. The dent defects were reduced by 1) changing from dry polishing method to wet polishing method, 2) storing stainless steel plates on storing tables and covering them by dust protectors, 3) improving cleaning equipment, 4) determining the relationship between the diameter of fisheyes/foreign matters in the release film and the defective proportion to encourage quality improvement of the vender. After the improvement, the defective proportion due to dent defects was reduced from 947 DPPM to 442 DPPM or 53.3% reduction. This improvement decreased defective cost of 666,529 baht per year .