Patent ID: 6419149
Filing Date: 2002-07-16
Classification: B23K,H01L,H05K

Abstract:
A method for producing a composite metal foil comprising a three-layered laminate, which laminate comprises a carrier layer, a barrier layer and a wiring-forming layer, said wiring-forming layer being etched to form a wiring of semiconductor packages, comprising the steps of(a) rolling in a vacuum chamber a first Cu-based metal foil having an average thickness of 50 &mgr;m or less and an average surface roughness Rz of 5 &mgr;m or less in both surfaces, and a second Cu-based metal foil having an average thickness of 20 &mgr;m or less and an average surface roughness Rz of 5 &mgr;m or less in both surfaces, followed by (b) vapor-depositing a metal having different etchability from that of Cu onto at least one of said first metal foil and said second metal foil to form said barrier layer having an average thickness of 1 &mgr;m or less; and thereafter (c) pressure-welding both metal foils via said barrier layer by rolling at a draft of 2% or less to form said barrier layer as a continuous layer substantially free from defects.