A Square Uniform UV Laser Beam for Screen Printing Enhancement and Photoresist Ablation for Ultra-miniature Chip Resistors

摘要

For today's "ultra-miniature" metric 0603, 0402 and 0201 thick film chip resistors and for next generation hybrid circuits, screen printing technology has reached its practical production limits. Yet, the industry desperately needs this low cost manufacturing process to be cost efficient. Current lithography processes, together with their associated clean rooms, mask exposure tools, etch processes steps, and more, are not able to meet production cost goals. This paper will show a new, direct ablation process to pattern the mask used in the termination process for an ultra-miniature 0402 metric chip R substrates. We will also examine how the square uniform UV beam can be used as a post screen printing clean-up step to dramatically reduce achievable feature sizes. This resolution/accuracy enhancement step is done after drying but before firing, resulting in the unfired organic materials ablating easily and cleanly. The ease of ablation, combined with today's high repetition rate Diode Pumped Solid State (DPSS) UV lasers, make this a very high speed, cost effective process. For today's hybrid circuits, having a fast, low cost method for producing fine lines with vertical walls, could be extremely attractive, particularly in high frequency applications.