Wirebonding - minimum contact area

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SUMMARY

The minimum contact area for wirebonding using a microscope and microprobe is influenced by the wire bonder and wire size. For a typical setup, a contact pad size of 220 x 220 µm is generally sufficient, but specific requirements depend on the bonding process. For ball bonding, the ball size should be approximately three times the wire size; thus, if using 1 mil (25 µm) wire, the ball would be 75 µm, necessitating a minimum pad size of 100 µm. Design for manufacturability (DFM) guidelines should be consulted for precise requirements.

PREREQUISITES
  • Understanding of wirebonding techniques
  • Familiarity with DFM (design for manufacturability) principles
  • Knowledge of bond pad design specifications
  • Experience with wire sizes and bonding equipment
NEXT STEPS
  • Review DFM documents related to wirebonding processes
  • Research specifications for different wire sizes and their corresponding bond pad requirements
  • Learn about the operational accuracy of various wire bonders
  • Investigate the impact of pad size on wirebonding reliability
USEFUL FOR

Chip designers, electrical engineers, and manufacturing professionals involved in semiconductor fabrication and wirebonding processes will benefit from this discussion.

Hyo X
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I am designing a mask for a chip which might be used for wirebonding.
What is the minimum contact area for wirebonding using a microscope and microprobe?
Currently my contact pads are 220 x 220 um. Is that big enough?
 
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Hyo X said:
I am designing a mask for a chip which might be used for wirebonding.
What is the minimum contact area for wirebonding using a microscope and microprobe?
Currently my contact pads are 220 x 220 um. Is that big enough?

There should be design rules for this in your process design guidelines. What DFM (design for manufacturability) documents do you have access to for this process?
 
The required bond pad size is dependent on the wire bonder and wire size. 220 x 220 is pretty large , but I have no idea what your bonder requires.

For example, the ball size (assuming ball bonding) may be 3 times the wire size and maybe you are using 1mil wire (25um) so the ball is 75um. You want the ball to be no more than 75% of the pad so that gives a min size of 100um. But the accuracy of the bonder (and possibly its operator) needs to be considered also.
 
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