Stock material or miscellaneous articles – All metal or with adjacent metals – Width or thickness variation or marginal cuts repeating...
Patent
1978-07-26
1980-11-18
Hunt, Brooks H.
Stock material or miscellaneous articles
All metal or with adjacent metals
Width or thickness variation or marginal cuts repeating...
174 52FP, 357 69, 357 70, 361421, H02G 1308, H05K 500, H05K 1500
Patent
active
042346665
ABSTRACT:
A carrier tape (20) is provided for assembling components to make semiconductor devices. The tape (20) is made from soft, copper foil (21). Patterns (27) containing clusters (24) of inner leads (28) and (30) are accurately formed into tape (20) for bonding to chips (52).
Tape (20) is indexed for bonding the free ends (36) of inner leads (28) and (30) to pads (54) of chip (52). Then tape (20) is indexed for bonding fixed ends (34) of leads (28) and (30) to stiff outer leads (86).
Leads (28) and (30) in cluster (24) are deformed into a precise bell-like shape called a "bug" with chip (52) riding horizontally on top of the bell. Bugging develops flexural and tensile stresses and bonding causes thermal stresses in leads (28) and (30). Such stresses can shift or twist bug (51); warp the structural margin (26) and holes (22) of tape (20), and they can distort adjacent lead clusters (24) on tape (20).
One or more stress relief sites (39) are provided in leads (28) and (30) to uniformly control such stresses. Sites (39) advantageously prevent stresses from being transmitted outside cluster (24). Also sites (39) aid in deformation of leads (28) and (30) to form bug (51).
The stress relief sites (39) permit a high density of lead clusters (24) per linear foot of web (21). Costly plastic substrates (12) are eliminated; and the likelihood of short circuiting in the assembled devices is reduced.
REFERENCES:
patent: 3258661 (1966-06-01), Mierendorf et al.
patent: 3947867 (1976-03-01), Duffek et al.
patent: 3978516 (1976-08-01), Noe
patent: 4003073 (1977-01-01), Helda
patent: 4026008 (1977-05-01), Drees et al.
patent: 4048438 (1977-09-01), Zimmerman
patent: 4109096 (1978-08-01), Dehaine
Lyman, "Electronics" Special report: film carriers star in high vol. 1C production 12-25-75.
Hunt Brooks H.
Lott R. D.
Watson D. C.
Western Electric Company Inc.
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