LINK-US Lab～Part2

Welcome to the world of ultrasonic bonding! ~ Exploring the Profound World of bonding Technology~

This is the LINK-US Lab Part2! In the previous part, we explained “bonding” extensively, and in this part, we will go deeper into our core technology, “ultrasonic bonding”.

Ultrasonic bonding is, as the name suggests, a technology that uses the vibration energy of "ultrasonic waves" to bond materials.

Ultrasonic vibration is used to remove the oxide layer to achieve atom-by-atom bonding. Atom-by-atom bonding prevents the formation of foreign matter, resulting in a strong and stable bond.

As introduced in the LINK US Lab Part1, in a broad sense, ultrasonic bonding exists as a technology within welding, but as the word “welding” was created from the word “melting,” and bonding by ultrasonic waves does not melt but adheres metal base materials together, we do not use ultrasonic welding, Therefore, we use the term “ultrasonic bonding” instead of "ultrasonic welding.

In English, welding and bonding are also used, but our ultrasonic metal bonding technology is called Ultrasonic Bonding, which is a technology for bonding metals without melting them.

In this part, we will guide you through the bonding technology by ultrasonic waves, from the basic knowledge of ultrasonic joining to its application and future, from the viewpoint of only LINK-US, a specialist of ultrasonic waves.

Contents

1. Principle and Features of Ultrasonic bonding
2. Types of ultrasonic bonding
3. Advantages and challenges of ultrasonic bonding
4. Case Studies of Ultrasonic bonding
5. Future of ultrasonic bonding

1. Principle and Features of Ultrasonic bonding

Ultrasonic bonding uses sound waves at high frequencies (20 kHz or higher) inaudible to the human ear, or "ultrasonic waves.

Specifically, a metal tool called a horn is vibrated and the vibrations are transmitted to the material to be joined. This causes the molecules of the material to vibrate violently, generating frictional heat. This heat causes the materials to soften and intertwine with each other, and when they cool and harden, the bonding is complete.

Features of Ultrasonic bonding

- Precise bonding: Fine parts and thin materials can be bonded precisely.

- Low thermal effects: Because the entire material does not need to be heated as in welding, it can be applied to materials that are sensitive to heat.

- Clean joining: No need for secondary materials such as adhesives or fluxes, making the joints environmentally friendly and neat.

2. Types of ultrasonic bonding

Ultrasonic bonding can be classified into several types according to vibration method and welding method.

Classification by Vibration Method

Linear Vibration

The horn vibrates up and down, causing friction between the surfaces to be joined and generating heat for welding.

Mainly used for welding resin and film.

The structure is simple, and relatively inexpensive equipment can be used.

Torsional Vibration

The horn vibrates in the direction of rotation, shearing the bonding surface and welding is done by generated heat.

Suitable for joining metals and composite materials.

Compared to linear vibration, stronger bonding is possible.

Complex Vibration

This vibration method combines linear and torsional vibration.

The advantages of each can be utilized for a wider range of materials and applications.

Classification by welding method

Melting

Thermoplastic resin is joined by melting.

Used for joining various plastic products such as toys and home appliances.

Solid phase

Bonds thermoplastic resins by intermolecular bonding force without melting.

Suitable for bonding films and sheets.

Compared to the melting method, deformation and deterioration caused by heat can be suppressed.

Friction

Bonds metals and other materials by softening them with frictional heat.

It is used for automotive parts, electronic parts, and other parts requiring high strength.

Example of combination of vibration method and welding method

3. Advantages and challenges of ultrasonic bonding

Advantage

• Low thermal effects: Since materials do not need to be melted at high temperatures as in welding, even heat-sensitive materials can be ed.
• Dissimilar materials can be joined: Different materials can be joined, such as metal and resin.
• High speed and high efficiency: Production efficiency is high because joining can be completed in a short time.
• Environmentally friendly: No adhesives, flux, or other secondary materials are required, resulting in a low environmental impact.
• Easy to automate: Suitable for automation using robots, etc., and contributes to reducing labor shortages.

Challenges

• Limited materials that can be joined: Ultrasonic joining is mainly applicable to thermoplastic resins and some metals.
  • It is not suitable for materials that do not easily transmit ultrasonic vibrations, such as thermosetting resins and glass.
• High initial capital investment costs: Ultrasonic joining equipment is more expensive than welding equipment.
  • In addition to the cost of the equipment, the cost of tools such as horns is also required.
• Lower bonding strength: Compared to welding, bonding strength may be lower.
  • Particular care should be taken when applying to areas where large loads are applied.

LINK-US Initiatives

LINK-US is constantly developing technologies to overcome these challenges.

• We are developing new vibration methods and horn shapes to improve bonding strength.
• We are improving our ultrasonic bonding equipment so that it can be applied to a wider range of materials.
• We offer consulting services to propose the best bonding conditions to meet our customers' needs.

4. Case Studies of Ultrasonic bonding

Ultrasonic bonding is used in a variety of fields.

• Automotive: engine parts, interior parts, exterior parts, sensors, batteries, etc.
  • Contributes to weight reduction, improved fuel efficiency, and safety.
• Electronic devices: smartphones, PCs, home appliances, wearable devices, etc.
  • Contribute to smaller, lighter, more functional devices.
• Medical devices: catheters, artificial blood vessels, blood bags, syringes, artificial joints, etc.
  • Contribute to safety, reliability and biocompatibility.
• Food: packaging containers, film packaging, etc.
  • Contributes to hygiene, sealing and preservation.
• Others: toys, stationery, daily necessities, clothing, building materials, etc.
  • A wide range of fields offer a wide range of possibilities.

LINK-US offers the optimal ultrasonic joining solutions in these areas to meet your needs.

5. Future of ultrasonic bonding

Ultrasonic bonding is expected to continue to develop in the future. In particular, it is expected to be introduced in the following fields

• Space development: manufacturing spacecraft and satellites that require lighter weight and higher strength
  • It is attracting attention as a highly reliable bonding technology that can withstand harsh environments.
• Aircraft: Weight reduction for better fuel economy, safety improvement
  • It is expected to be used for joining composite materials such as carbon fiber reinforced plastics (CFRP).
• Regenerative medicine: cell and tissue bonding
  • It is expected to be applied to suturing during surgery and to the manufacture of artificial organs.
• Wearable devices: smaller, lighter, more sophisticated
  • It is expected to contribute to the realization of more comfortable and multifunctional wearable devices.
• IoT: bonding sensors and devices
  • It is expected to be a fundamental technology that supports the development of an IoT society.

LINK-US will contribute to the evolution of ultrasonic joining technology in these fields as well.

LINK-US expands the possibilities of ultrasonic joining

As a pioneer in ultrasonic joining, LINK-US is constantly challenging new technologies. We will continue to pursue the possibilities of ultrasonic joining to solve our customers' problems and create the future.

LINK-US Lab will continue to provide a variety of information on ultrasonic technology. Please look forward to our next article!