MULTI-GAUGE METAL STRIP, METHOD OF FORMING SAME AND LEADFRAMES PRODUCED THEREFROM

摘要

A novel multi-gauge strip is disclosed wherein the multi-gauge strip 10 comprises a first strip of metal 12 having a first thickness 14. A second narrower strip of metal 18 has a second preferably greater thickness 20 than the first strip, and coextends longitudinally with the first strip of metal 12 and intimately bonded in direct metal-to-metal contact without the use of a welding or brazing material. The multi-gauge strip is produced by pressure bonding the two equal width strips in face-to-face direct metal contact, machining one or more grooves longitudinally in one of the two layers (18) of a sufficient depth to expose the under layer (12) and slitting the bonded strip along the grooves as at (62, 64) and at 66 along the unmachined area (52) between the two adjacent grooves. Optionally the bonded strip can be trimmed along both edges as at 57 and 58. The strip is useful for stamping out leadframes comprising high strength contact fingers formed from the exposed thinner layer (12) and a thicker thermally conductive heat sink frame portion formed from the double thickness section of the bonded multi-gauge strip.