Metal working – Method of mechanical manufacture – Electrical device making
Patent
1995-10-23
1996-08-27
Vo, Peter
Metal working
Method of mechanical manufacture
Electrical device making
295663, 216 14, 21912169, 257666, 437220, H01R 4302, H01L 2160, H01L 23495, B23K 2600
Patent
active
055488900
ABSTRACT:
In a method for forming a lead frame (1) from a metallic plate, a metallic plate (11) is first etched to form outer leads (4) and outer portions (3b) of inner leads of the lead frame (1). Inner portions (3a) of the inner leads (3) are then laser-cut under the condition that a joint portion (7) is left so as to interconnect the inner leads (3) at their distal ends. Mechanical surface treatment and chemical surface treatment are then carried out to remove dross (10), spatters (9) and oxide films deposited during the laser cutting. Inner areas of the inner leads (3) connected to respective terminals of a semiconductor chip are then plated with gold to form plated terminal portions (3A). Subsequently, the region of the lead frame other than the outer leads (4) is coated with a protective film for solder plating and the outer leads (4) are plated with solder. The joint portion (7) left at the distal ends of the inner leads (3) is then cut off by laser cutting so that the inner leads (3) are separated from one another, thereby forming a final lead frame pattern. The protective film for solder plating is then removed, followed by washing and drying. The inner leads (3) are prevented from being curved due to thermal deformations with the laser cutting, resulting in highly accurate processing.
REFERENCES:
patent: 2156262 (1939-05-01), Fink et al.
patent: 4704187 (1987-11-01), Fujita
patent: 4711700 (1987-12-01), Cusack
patent: 4820658 (1989-04-01), Gilder, Jr. et al.
patent: 4978830 (1990-12-01), Millerick et al.
patent: 5270570 (1993-12-01), Westerkamp
Miyanagi Naoki
Nagano Yoshinari
Okumura Shinya
Sakurai Shigeyuki
Shimomura Yoshiaki
Hitachi Construction Machinery Co. Ltd.
Vo Peter
LandOfFree
Lead frame processing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lead frame processing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lead frame processing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1048381