TECHNOLOGYI INNOVATE ON MANUFACTURING

Ultrasonic bonding

technology

On this page, after explaining the mechanism of bonding and the process of ultrasonic bonding, we will introduce how adwelds deals with ultrasonic bonding.

Ultrasonic bonding: the mechanism of bonding

Ultrasonic reduces the metal objects to nearly an “interatomic spacing” level to bond

How to break down a metal to an “interatomic spacing” level

There are three ways to break down an object to the “interatomic spacing” level

  • Not only applying “load” and “heat” to metal, but also to an object would create deformation and reduce the metal/object to the “interatomic spacing” level . Applying only load or heat also breaks down the metal/object to the “interatomic spacing” level .
  • Above all, applying ultrasonic is the most efficient way to reduce the metal/object. This is what we call the “ultrasonic bonding method.” Ultrasonic alleviates load and heat conditions when bonding.
How to break down a metal to an “interatomic spacing” level
Why is it effective to bond when the metal/object reduce to the “interatomic spacing” level?

Use the bonding power among atoms to bond the applications together

  • Chemical bonding/metal bonding: Share free electrons
  • Covalent bonding: Share electron pairs
  • Ion bonding: Free electrons form chemical compounds
  • Physical bonding: Force among nuclei works (Van der Waals force)
  • Mechanical bonding: Put objects together mechanically
Why is it effective to bond when the metal/object reduce to the “interatomic spacing” level?
There are three ways to break down an object to the “interatomic spacing” level

Obstructive factors listed below must be eliminated for bonding
Usually, measures of applying ultrasonic or flux (when soldering) are taken to eliminate them

  • Obstructive factors listed below must be eliminated for bonding
    Usually, measures of applying ultrasonic or flux (when soldering) are taken to eliminate them
  • Oxide on the surface of metal
    Almost all the metal create oxide on the surface (behavior depends on the application)
There are three ways to break down an object to the “interatomic spacing” level
Mechanism of Ultrasonic Bonding

Diagrams below show ultrasonic processes how ultrasonic rigidly bonds applications without dissolving them.

  • Step 1 Apply pressure to the applications and apply ultrasonic
  • Step 2 Friction removes contaminations on both surfaces of applications
Mechanism of Ultrasonic Bonding
  • Step 3 These contact points on the interfaces become welding points
  • Step 4 The interface deforms when pressure is applied, but ultrasonic accelerates the deformation and the bonding area spreads. Therefore, two applications bond together without using heat with strong rigidity.
Mechanism of Ultrasonic Bonding
Mechanism of Ultrasonic Bonding

Ultrasonic Bonding: Cool Bond Process

This is a process developed together with Kyushu University an advanced ultrasonic technology, which bonds application at room temperature.

Currently working on bonding 300,000 bumps at once

Fusion technology that consist of adwelds’ ultrasonic bonding technology and Kyushu University’s compliant micro bump technology.

  • adwelds ultrasonic bonding technology controls the profile of boding loads and ultrasonic power digitally to acquire excellent bonding
  • Microjoining technology, the cutting edge technology which Kyushu University created, allows to form a sharp-end bumps, the size is as big as 10μm, suitable for ultrasonic bonding
Currently working on bonding 300,000 bumps at once
What field can this technology apply to?

It can be useful in a 3D semiconductor or flexible electronics fields

  • Make 3D heterogeneous applications (infrared image sensor, etc.)
  • Installing organic substrate for semiconductor packaging
What field can this technology apply to?

Ultrasonic bonding: ABB Process (adwelds Bind Bonding Process)

Demand: Want to bond applications that are said to be difficult

adwelds developed a technology that bonds applications via a binder

  • Merit 1: Bond solderless Cu terminals on a printed circuit board

Merit 1: Bond solderless Cu terminals on a printed circuit board
[Conventional Process]

When bonding Cu electrodes on the printed circuit board, it required soldering process. In order to increase reliability under high temperature, developing a technology of solderless direct bonding was on high demand. However, the ground of electrode is made of plastic resin that is soft; as shown in the diagram on the right, and damages were made on the Cu foil.

Demand: Want to bond applications that are said to be difficult

[ABB Process]
Adwelds developed a technology that bonds applications via a binder, a metal material that deforms easily such as Al. By using a metal binder, it stabilizes the bonding process without damaging electrodes on the printed circuit board.

Demand: Want to bond applications that are said to be difficult
  • Merit 2: Bonding both tips of applications

[Conventional Process]

The conventional process put applications on top of each other, so the welding part gets thick. Applications that are difficult to weld when the welding part gets thick, needed to take measures.

Demand: Want to bond applications that are said to be difficult

[ABB Process]
adwelds found a solution to this problem, the ABB Process: Place two applications as shown in the diagram and weld the binding materials; such as Al foils. The thickness of the welding part is the thickness of Al foils.

Demand: Want to bond applications that are said to be difficult
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