JPS5976829A - Manufacture of bonding wire - Google Patents

Abstract

PURPOSE:To manufacture a bonding wire with superior breaking strength by melting gold of specified purity or above, spouting the molten gold, solidifying it by rapid cooling, and drawing the resulting wire. CONSTITUTION:Gold of >=99.9% purity is melted, and the molten gold is spouted from a nozzle and solidified by rapid cooling to make the gold grains fine. The resulting wire is mechanically drawn to regulate the diameter and to provide a mechanically worked surface to the surface of the bonding wire.

Description

[Detailed Description of the Invention] The invention relates to a method of manufacturing a bonding wire.
In particular, the present invention relates to a bonding wire manufacturing method using a combination of liquid quenching and wire drawing.

Conventionally, bonding wires made of pure gold have been widely used for electrical connections between the chip electrodes of semiconductor devices and the connecting parts of lead frames or cases that connect to external leads. A bonding pad is formed, and gold or silver is also used for the lead frame or case, and a bonding wire containing gold with a purity of 99.99% or more is used to connect the two. However, this bonding wire was connected by crimping at a temperature of about 300° C., by balling up with an electric arc and then thermocompression bonding, or by crimping with ultrasonic energy. This type of bonding wire for semiconductor devices is
It was manufactured by wire drawing using pure gold as a raw material, but it had the disadvantage that if the bonding speed was high, it could not be bonded well because the wire was as thin as 0.025φ. ``Therefore, conventionally, Ca, Be,
Ge, Ni, Fe.

Attempts have been made to increase mechanical strength by incorporating 0.1% or less of Co, Ag, etc. into Au. However, although such bonding wires have poor bonding properties, they do not have sufficient mechanical properties, especially breaking strength, and have the disadvantage of causing wire breakage when used in high-speed automatic bongos. .

The present invention has been made to eliminate such drawbacks, and is characterized by melting a gold alloy with a purity of 99.9% or more, blowing this molten gold alloy out of a nozzle, cooling it rapidly, and then wire-drawing it. This is a method for manufacturing a bonding wire.

In the present invention, the purity of gold is set to 99.9% or higher because of the non-metallic elements contained in the target, carbon, which is difficult to oxidize.
u, Fe, Mg, Si, AI, Ca.

Base metals such as B, Cr, Zn, Sn, and Pb are oxidized to form Au.
This is because the bonding properties of the metal are inhibited and the bonding properties are deteriorated. In addition, the reason for rapidly cooling the wire by blowing it out of a nozzle is to disperse the gold crystal grains very finely into the bonding wire, thereby exhibiting toughness that cannot be achieved with conventional wire drawing methods.

In addition, as a method of rapidly cooling, it is possible to spray it into the atmosphere, or to spray it into a rotating drum or rotating running water. However, the wire obtained by such a method of rapidly solidifying molten metal has a drawback that the wire diameter varies slightly. Therefore, the rapidly cooled and solidified wire is mechanically drawn to adjust the wire diameter and to make the surface of the bonding wire into a machined surface similar to that of a conventional bonding wire.

Hereinafter, specific examples and comparative examples will be described in order to clarify the effects of the bonding wire for semiconductor devices according to the present invention.

〔Example〕

As shown in the figure, a cylindrical drum 1 whose negative side is closed rotates around an axis 2 of 25 Or, p, m. This inner diameter is 50
Water is supplied into the drum of the 0φ dragon by a water supply pipe 3, and a water layer is provided on the side wall 4 of the drum 1, and the thickness of the water layer is adjusted by the position of the drain pipe 5. 3.5 kg/c of molten gold was molten in this water layer from the 0.1φ nozzle of the gold injection device 6.
It was injected as a jet at a pressure of m' to create a gold phase line of 95 μφ. This gold phase wire was applied to a wire drawing machine to produce a bonding wire of 25 μφ.

[Conventional example]

A 25 μΦ bonded cotton was made by continuously drawing a 6Φ gold wire.

Next, the breaking strength and elongation rate of the bonding wire of the above example and the conventional example were compared, and the bonding properties using an electric arc were also compared, and the results shown in the table below were obtained.

Claims (1)

[Claims] A method for manufacturing a bonding wire, which comprises melting gold with a purity of 99.9% or more, blowing the molten gold out of a nozzle, cooling it rapidly, and then drawing it.