Evaporation Masks Using Organic Materials for Fine Line Repair and Solder Evaporation
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
An evaporation mask for fine line repair and solder evaporation using organic materials allows small feature sizes and other geometries desired that are not obtainable using metal masks. For fine line repair, a physical mask with a lithographically defined opening for localized metal deposition is made. Fig. 1 shows a KAPTON* film 11, about 2 mils thick, held by adhesive 12 to a metal (aluminum) or a ceramic ring 13 for thermal expansion match to the substrate with lines for repair. A thin (2 mm) aluminum film 14 or other protective metal is evaporated onto the top polyimide surface 11 and is chemically etched 15. The underlying polymer is etched by excimer laser, microwave, plasma or reactive ion etch, to form a through via 16 with a slightly tapered slope 17 of about 70Œ. The entire mask 11 is then inverted, as in Fig.