Connection structure, power module and method of manufacturing the same
View Patent ↗In ultrasonic bonding of a metal terminal to a substrate pad, a thin buffer metal layer which is formed of a soft metal or a highly slidable metal is interposed between a terminal edge and a pad so as to prevent direct contact between an end of the terminal and the pad upon bonding. This makes it possible to prevent abrasion and a crack in the pad at the end of the terminal caused by pressure and an ultrasonic wave upon the ultrasonic bonding. This makes it possible to realize a compact bonded structure with high reliability.
1. A connection structure having a radiator plate, a first insulating layer, a metal pad, and a terminal sequentially laminated in this order,
wherein a first region and a second region exist between the metal pad and the terminal;
wherein a buffer metal layer, which is formed of one of tin or indium, is interposed between the metal pad and the terminal in the first region, and the metal pad and the terminal directly connect at the second region,
wherein the first region includes a region just below an edge of the terminal, and
wherein the metal pad and the terminal are connected by an ultrasonic bond.
2. A method of manufacturing a connection structure having a radiator plate, a first insulating layer, a metal pad, and a terminal sequentially laminated in this order, the method comprising the steps of:
interposing a buffer metal layer, which is formed of one of tin or indium, between the metal pad and the terminal; and
ultrasonic bonding the metal pad and the terminal;
wherein the buffer metal layer is formed between the metal pad and the terminal at a first region, and the metal pad and the terminal directly connect at a second region.
3. The method of manufacturing a connection structure according to claim 2 , wherein the buffer metal layer is provided just below an edge of the terminal at the first region.
4. The method of manufacturing a connection structure according to claim 2 , wherein the terminal includes a protrusion formed opposite the buffer metal layer at the second region.
5. The method of manufacturing a connection structure according to claim 2 , wherein the terminal includes a convex curve surface formed opposite the buffer metal layer at the second region.