Gold Bonding Wires in Electronics

 Gold bonding wires are thin filaments made of gold that are used to create electrical connections in various electronic devices and integrated circuits (ICs). These wires play a crucial role in the packaging and assembly of semiconductor devices. Here are some key points about gold bonding wires:

1. Material: Gold is the preferred material for bonding wires due to its excellent electrical conductivity, corrosion resistance, and ductility, which allows it to be drawn into extremely thin wires without breaking.

2. Diameter: Gold bonding wires typically have diameters ranging from 18 to 33 micrometers (μm), which is around 1/5 to 1/3 the thickness of a human hair.

3. Bonding Process: The bonding process involves attaching one end of the gold wire to a bond pad on the semiconductor chip (ball bond) and the other end to a lead frame or substrate (wedge bond). This creates an electrical connection between the chip and the package.

4. Ball Bonding and Wedge Bonding: Two common techniques used for bonding are ball bonding and wedge bonding. In ball bonding, a ball is formed at the end of the wire using heat and pressure, and then bonded to the chip. In wedge bonding, the wire is pressed against the bonding surface using ultrasonic energy or thermosonic energy.

5. Fine Pitch Bonding: As semiconductor devices become smaller and more complex, the bond pads on the chips are spaced closer together, requiring finer pitch bonding capabilities. Gold bonding wires are capable of being bonded at extremely fine pitches.

6. Reliability: Gold's resistance to corrosion and oxidation ensures reliable electrical connections over the lifetime of the electronic device, even in harsh environments.

7. Applications: Gold bonding wires are widely used in the packaging of integrated circuits, microprocessors, memory chips, and various other electronic components and devices, including those used in consumer electronics, computers, telecommunications, and aerospace applications.

Gold bonding wires play a vital role in enabling the miniaturization and high-density packaging of modern electronic devices, ensuring reliable electrical connections and facilitating the integration of complex semiconductor components.

Gold bonding wire is considered the single most important application of gold in terms of tonnage of gold utilized per annum.

Wire bonding is a technique used to join very fine gold wire (usually thinner than a human hair at 10–200 µm) from one connection pad to another, thus completing the electrical connection in an electronic device. Back in 1957, the process was developed in the Bell Labs in the United States.

Today, literally billions of wires are bonded every year worldwide and most of them are utilized in the integrated circuits (ICs) that are taken for granted in all manners of electronic goods.

Example of Gold Bonding Wire in an Integrated Circuit

Gold has several benefits, which make it the preferred material for bonding wire. These benefits include high electrical conductivity, good corrosion resistance, and the capability to be bonded in position in an ambient environment. Gold remains the most popular metal for bonding wire and is specially refined to high purity (999.99% gold). Users can refer to the UtiliseGold Directory, for suppliers of the gold bonding wire.

How Gold Bonding Wire is Used?

Basically, there are two forms of wire bonds—ball bonds and wedge bonds. Gold wire can be bonded in the shape of a ball or a wedge, making it highly versatile. The basic process for making a gold wire bond is described below.

A small flame or spark is used to locally melt the ends of the gold wire in order to form a spherical ball that has roughly twice the diameter of the wire.

The spherical ball is thermosonically welded to a metalized pad on the semiconductor.

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

The wire is welded thermosonically to the metalized pad of the device package.

The wire is cut using the sharp edge on the tool, and its length is allowed to protrude to form the subsequent ball.

The continuous quest for cost reduction, smaller components, and increasing system functionality are all competing demands in the electronics sector. To help chip manufacturers and designers to deal with these competing demands, insulated wire bonding technology could be used in the coming days. This involves applying insulation to bare gold bonding wires, thus preventing short circuits, and enabling previously impossible chip designs to be realized.