Nippon Steel Corporation

Yoshio Ohzeki

Yasuhide Ohno

A method for efficiently and accurately manufacturing fine metal balls such as solder is provided. A liquid is poured into a vertically elongated cylindrical container, where the liquid is heated up to a temperature higher than the melting point of the metal from its top to middle regions and maintained at a temperature lower than the melting point in the lower region. Metal pieces each of which is made to have a predetermined volume are dropped into the container. The metal pieces are heated and melted while passing the high-temperature region, and take the shape of a substantial sphere due to their own surface tension. However, when the balls reach the low-temperature region, they are cooled and solidified to become substantially perfect metal balls. Since this process can be successively performed, a large number of fine low-melting-point metal balls with high dimensional accuracy can be efficiently manufactured by combining the process with a wire cutter with a high accuracy.

Method of producing fine metal balls

This invention relates to a bonding wire (3) for connecting electrodes of a semiconductor element to outer leads (2). The bonding wire (3) consists of Cu of not less than 1 wt % but less than 5 wt %, and the balance Au and incidental impurities. The bonding wire is superior in rupture strength and bonding strength. Even if the diameter is thinned to about 10 .mu.m, high reliability may be insured for connection.

Bonding wire for semiconductor element

A composite lead frame comprising a lead frame (10), leads (28) supported on a plastic film (22 ') having a device hole (24), and a metal (14, 32) for mounting a semiconductor chip (34) is disclosed. The lead frame (10) has a plurality of inner lead portions (12) each of which is bonded to each of the leads (28), respectively. The metal (14, 32) also supports the leads (28) through the plastic film (22'). The metal (14, 32) may be bonded to the lead frame (10) through an adhesive tape (16), or may be integrated with the lead frame (10). Bonding wires (36) to connect the leads (28) and the semiconductor chip (34) can be easily and securely bonded to the leads (28) in virtue of the metal (14, 32) supporting the leads (28). Additionally, a semiconductor device incorporating the composite lead frame has efficient heat dissipation and reliability by virtue of the metal pad.

Growing community of inventors

Kawasaki, Japan

Yoshio Ohzeki