Metal working – Method of mechanical manufacture – Electrical device making
Patent
1987-11-25
1989-07-11
Arbes, Carl J.
Metal working
Method of mechanical manufacture
Electrical device making
357 70, 357 80, 361400, H01R 4300
Patent
active
048458422
ABSTRACT:
A metal sheet (58) to be etched into lead frames has an emulsion coating (60) on its top and bottom. A bottom glass plate (56) has a mask pattern (64) defining the pattern of metal from the sheet (58) that is to remain after etching to form the lead frame. The pattern (64) has a first line width d1. A top glass plate (62) has a corresponding mask pattern (66) also defining the pattern of metal from the sheet (58) that is to remain after etching to form the lead frame. The mask pattern (66) has a second line width d2 that is less than the first line width. The emulsion coating (60) on the sheet (58) is exposed through the mask plates (56) and (62), and the emulsion coating is developed in a conventional manner to give photoresist patterns (64a) and (b 66a) or (64b) and (66b) on the metal sheet (58). The patterns (64a ) and (66a) are produced when the mask plates (56) and (62) are in exact registration with each other, and the patterns (64b) and (66b) are produced when the mask plates (56) and (62) are misaligned to the greatest extent permissible while avoiding lead sweep. The metal sheet (58) with the photoresist patterns (64a) and (66a) or (64b) and (66b) in place is then etched in a convention etching process to produce a lead frame and the photoresist patterns are stripped from the resulting etched lead frame. When the leads from the lead frame formed in this way are bent in the fabrication of an integrated circuit package substantially less lead sweep results.
REFERENCES:
patent: 3544857 (1970-12-01), Byrne et al.
patent: 4234666 (1980-11-01), Gursky
patent: 4704187 (1987-11-01), Fujita
IBM Tech Discl Bull, vol. 28, No. 12, May 1986, pp. 5174-5175.
IBM Tech Discl Bull, vol. 30, No. 5, Oct. 1987, p. 288.
Harline Richard D.
Miller Herbert
Arbes Carl J.
National Semiconductor Corporation
LandOfFree
Process for reducing lead sweep in integrated circuit packages does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for reducing lead sweep in integrated circuit packages, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for reducing lead sweep in integrated circuit packages will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-427516