WHAT IS AU (GOLD) STUD BUMPING

Stud bumping can be done using either Cu (Cupper) or Au (Gold). Here at Intech we have Au stud bumping capabilities. Stud bumping is rather similar to the ball bonding process.

The difference being the wire is terminated once the ball is formed. The capillary descends to touch the bond pad and once in contact with the bond pad a combination of heat, pressure and Ultrasonic energy is applied to form the bond between the surface and the wire. Heat softens the material and ultrasonic energy causing micro vibration facilitating the breaking of oxide layers which promotes atomic intermixing. Pressure helps in deforming the wire to make intimate contact with the bond surface. Once the stud is formed the capillary is lifted and wire is them clamped and torn to leave a stud with a protruding tail.

After the ball formation, we can clam and tear the wire at heights up to 60 µm. This means leaving just the stud or leaving the stud with a custom tail height.

Illustration 1: Several stud bumping profiles with different tail lengths.

Why use Stud bumping?

Relatively low cost Prototyping: With a minimal setup cost, we are able to die individual units. This could be either die level or die attached to a substrate. Unlike solder bumping, stud bumping takes less effort in a R&D setting.

Good for Precision Application: Able to achieve a co-planarity of +/- 2.5 µm.

Flux Free Process for MEMS application: Solder Bumping process for oxide ess requires the application of flux for surface prep and oxide removal. For devices sensitive to flux and flux related contaminations Stud pumping is a perfect choice.

Illustration 2: Au Stud Bumping with optimized profile parameters.

Please feel free to contact Intech Technologies for any and all stud bumping requests. We will work with you to optimize the bumping profile to exactly match your exact specifications.

Structured Data

What is a stud bump? Remainder of wire bond terminated once the ball is formed.

What is stud pumping material? Mainly Au (Gold) and Cu (Cuppor)

Why stud bumping? Cheaper alternative to wafer solder bumping, able to pump at die or unit level, great for prototyping and it is good for applications that require flux free bumping solution.

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