Advantages of Gold Bonding Wire

Topics Covered

Overview
Example of Gold Bonding Wire in an Integrated Circuit
Using Gold Bonding Wire
Insulated Bonding Wire

Overview

Gold bonding wire is the single most important use of gold in terms of tonnage of gold used per year. Understand more about the gold bonding wire process here.

Wire bonding is the method used to attach very fine gold wire (typically thinner than a human hair at 10-200microns) from one connection pad to another, completing the electrical connection in an electronic device. The process was developed as long ago as 1957 in the Bell Labs in the US. Nowadays literally billions of wires are bonded every year in the world and most are used in the integrated circuits (ICs) we take for granted in all manner of electronic goods.

Example of Gold Bonding Wire in an Integrated Circuit

Gold has many advantages as the material of choice for bonding wire including good corrosion resistance, high electrical conductivity and the ability to be bonded into position in an ambient environment. It remains the most popular material for bonding wire and is specially refined to high purity (999.99% gold). For suppliers of gold bonding wire please see the UtiliseGold Directory.

Using Gold Bonding Wire

There are basically two forms of wire bonds; wedge bonds and ball bonds. Gold wire can be bonded in the shape of a wedge or a ball making it extremely versatile. The basic process for making a gold wire bond is shown below:

A spark or small flame is used to locally melt the end of the gold wire so as to form a spherical ball that is approximately twice the diameter of the wire.

The ball is thermosonically welded to a metallised pad on the semiconductor

A loop of wire is formed as the bonding capillary moves across to the contact pad of the device package or circuit board

The wire is thermosonically welded to the metallised pad of the package

The sharp edge on the tool is used to cut the wire, leaving a length protruding to form the next ball

The continuing drive for smaller components, increasing system functionality and cost reduction are all competing demands in the electronics industry. To help chip designers and manufacturers address these competing demands, insulated wire bonding technology may be used in the future. This consists of insulation applied to bare gold bonding wires, so avoiding short circuits and allowing for previously impossible chip designs to be realised. See www.microbonds.com for more information.

Insulated Bonding Wire

This new advanced form of gold bonding wire offers the opportunity for improvements in microchip design and packaging.

The drive for smaller components, increasing system functionality and cost reduction are all competing demands in the electronics industry. To help chip designers and manufacturers address these competing demands, an insulated wire bonding technology known as X-Wire™ has been developed by a Canadian company, Microbonds Inc in cooperation with several leading gold bonding wire companies around the world.

Microbonds’ X-Wire™ Technology consists of a proprietary insulation applied to bare bonding wires. The technology overcomes the inherent limitations of bare wire bonding interconnections which have to be designed to ensure that the bare wires do not touch, so avoiding short circuits. In contrast when using insulated wire, chip designers can reduce the criticality of wire clearance, allowing for previously impossible chip designs to be realised. Insulated bonding wires have been added to the electronic industry’s technology roadmap (2006 ITRS Roadmap.)

X-Wire™ has been successfully tested by industry participants for bond integrity, intermetallic formation, wire bonding yield and reliability. Tanaka Denshi Kogyo K.K., the leading global supplier of gold bonding wire have just certified the technology readiness of Tanaka to manufacture X-Wire™ from its Saga, Japan production facilities.

Source: World Gold Council

For more information on this source please visit World Gold Council