What is Wire Bonding?
Printed Circuit Boards (PCB) have become integral to modern-day electronics. One of the aspects of these circuit boards is PCB wire bonding. It is used for producing micro-electronic components.
You can read this article on wire bonding to better understand their types, materials used, applications, and so on.
An Introduction to Wire Bonding
Wire bonding is the technical process to create interconnections between semiconductor chips and substrates. One of the basic objectives of wire bonding is to establish a connection between the integrated circuits (IC) and electrical appliances.
These wire bonds bridge electrical signals to cross the gaps between the ICs and substrates. It is also an efficient option when combining a few integrated circuits or connecting a few printed circuit boards.
A thin wire is used with a combination of heat, pressure, and ultrasonic energy to create wire bonds for electrical interconnections. The wire bonding also helps conduct heat and ensures the semiconductor devices’ reliability and functionality.
Wire bonding is also crucial to assembling and packaging integrated circuits (IC). The wire bonds are necessary to establish electrical connections for transmitting signals, distributing power, and managing the thermal resistance of your devices.
The Need to Use Wire Bonding
The following are some of the reasons that PCB wire bonding is useful —
- Using a wire bonding is crucial to provide electrical connections to Integrated Circuits (IC).
- It also bridges the gaps present between the ICs and substrates.
- They are flexible and cost-effective options for your mass production needs.
- They also provide efficient and precise placement of the wire bondings.
- Wire bonding also provides a level of stability to the finished product.
- The chances of short circuits occurring are quite low.
- Corrosion due to moisture is also reduced because of the durability of the wire bonds.
The Various Types of Wire Bonds
The various types of wire bonding are as follows —
Ball Bonds
Ball bonding is one of the most common ways to make electrical interconnections. The ball bond is formed by making a sphere/ball with the ends of wires. The wire is bonded to a bond pad using a flame or spark. It offers a reliable and stable connection.
A combination of temperature, pressure, and ultrasonic energy forms these ball bonds. The ball bonding technique usually uses gold or copper wires – gold is more commonly used.
Wedge Bonds
Wedge bonding is another common type of IC wire bonding. A specialized wedge tool creates a wedge-shaped bonding capillary between the wire and bond pad. Wedge bonding offers mechanical stability and durability.
Force and ultrasonic energy form bonds in this type of wire bonding. The wedge bonding technique usually uses gold and aluminum wires – aluminum is more commonly used at an ambient temperature.
Ribbon Bonds
Ribbon bond involves joining a thin wire to the IC or substrate. It is in some ways similar to round wedge bonding. This type of wire bonding uses ribbons and leads to the formation of parallel bonds.
The Applications of Wire Bonding
Wire-bonding PCBs can be commonly found in day-to-day appliances to ensure their components are durable and functional.
Wire bonding is common in simple appliances like mobile phones and laptops. It is also found in high-end technological equipment, like microcomputers and microcontrollers.
The applications of wire bonding are spread across various industries. They are widely used in automotive, medicine, computing, communications, etc.
The following are the various applications of PCB wire bonding –
- Mobile Phones
- Laptops
- Microcomputers
- Microcontrollers
- Microprocessors
- Sensors
- Integrated Circuits (IC)
- Controls
- Infotainment
- Medical Stimulators
- Medical Implants
- 5G Communications
- Chipsets
- Power Devices
The Advantages of Wire Bonding
The following are some of the advantages of wire bonding —
- Wire bonds are highly flexible and are also known for their durability.
- They are also one of the common ways of implementing sensor solutions.
- It allows for high-quality transmission of signals.
- You can enjoy cost-saving benefits in the production of wire bonds.
- The shape of the chips, packages, and substrates is quite flexible.
- You can handle quite complex printed circuit boards in an easy way with wire bonds.
The Materials Used for Wire Bonding
Some of the common materials used for ic wire bonding are —
Gold
Gold is one of the most commonly used for wire bonding. It is mainly used for the ball bonding process. It offers an interconnection that is highly electrically conductive. Gold can also easily bond with heat, pressure, and ultrasonic energy.
Gold is mainly used for interconnections of high-frequency.
Copper
Copper is another one of the preferred options for wire bonding. It is commonly used for many semiconductor and microelectronic applications. The cost of copper is lower when compared to gold and offers the same level of performance. Copper is also less conductive than gold.
Cooper is mainly used for interconnections with low frequency.
Aluminum
Aluminum is used explicitly for ultrasonic wedge bonding. For this material, force and ultrasonic energy are essential for forming bonds. It is mainly preferred for signal transmission and processing.
Aluminum is mainly used for standard applications with moderate frequencies.
Silver
Silver has good electrical properties for wire bonding. $It has the highest thermal and electrical conductivity. This material can also bond with different pad materials quite efficiently.
Silver is mainly used for niche applications that need maximized conductivity.
The Quality Inspection Process of Wire Bonding
When inspecting the wire bonding, there are a few things to check. They are as follows –
- Check the accuracy of the bond placement and its positioning.
- Check the angle of the orientation of the beads about the lead frame edges.
- Check the quality of the bond integrity – the shapes and attachments.
- Check the wire shape and the loop height.
- Ensure the wires are placed correctly and aren’t too low.
Conclusion
Wire bonding is considered an efficient and affordable option for interconnection for integrated circuits and printed circuit boards in the electronics industry.
Wire bonding is a highly technological process to make precise and durable electrical connections.
