The use of laser direct imaging (LDI) processing for outer layer circuit pattern generation and the benefits already obtained with this process have encouraged attention to be focussed on the possibility of using laser direct imaging soldermask (LDISM) in the secondary imaging stage of printed circuit board (PCB) fabrication. As feature sizes on advanced interconnects have continued to diminish and the accompanying spacing between circuit features decreases, the requirement for accurately placing and scaling solder dams and apertures has become more critical in order to ensure that a high yield of finished product can be obtained. Consequently the traditional process of creating photographic artworks for soldermask exposure is rapidly becoming a crucial step that can have significant yield implications due to both environmental conditions and registration issues. The use of LDISMs in combination with specially developed LDI exposure systems is an enabling technology which can offer the benefits of a “standard” mask application process and the positional accuracy and individual image scaling required for guaranteeing improved yields for high density interconnect (HDI) panels.
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