STUDY THE ETCHING MECHANISM OF PHOTOSENSITIVE DRY FILM ON DEPOSITING GOLD DURING FABRICATION OF PRINTED-CIRCUIT BOARD

A photosensitive dry film is etched while depositing gold on the panel of a nickel-plated printed circuit. This study examines the etched su rface by conventional optical microscopy. However, an more accurate an d convenient method, UV quantitative analysis method, is also develope d. In addition, the mechanisms of etching photosensitive dry film are thoroughly examined. According to these results, OH-, H-2, O-2 and sti rrer an four critical factors to be considered while etching photosens itive dry film during the deposition of gold. However, OH- concentrati on is the most influential factor. If a flow system is used during the deposition, the etched concentration of photosensitive dry film can b e significantly reduced. (C) 1997 Elsevier Science S.A.