FORMATION OF BUMP FOR BONDING

PURPOSE:To obtain a bump, at a low cost, which shows the long-term stability and which is capable of bonding stably by a method wherein, after the tip of a copper wire has been shaped to be spherical, this spherical part has been bonded to a material to be bonded and the copper wire has been cut, the spherical part is pressurized and formed by using a tool having a recessed face in such a way that its surface shows a spherical shape or a gently-sloping protruding face. CONSTITUTION:The tip of a copper wire 10 is shaped to be spherical by using a capillary chip 11; this spherical part is pole-bonded onto a copper lead 2. Then, the copper wire 10 is cut at the upper part of a pulled ball 12. During this process, a protruding part 13 remains at the upper part of the ball 12; this protruding part damages a semiconductor chip during a tape-carrier bonding process and lowers the bonding performance extremely; accordingly, this part is processed by using a tool 14 having a recessed face in such a way that its surface shows a spherical shape or a gentlysloping protruding face. By forming this type of shape, the part is bonded by being accompanied by deformation during a bonding process; the stable bonding process is executed after an oxide film or the like on the surface has been removed and the surface of a metal has been exposed.