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Metal finishing Q&As since 1989

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Electroless Nickel & Immersion Gold for Ultrasonic Wire Bonding

2000

(I attached a file which have three pictures of plated surface. These pictures were taken from quality samples which have enough ductility to endure ultrasonic shock.)

Dear Adviser,

Our company is manufacturing flexible PCB. We have some problem with crack on the pad (*plated with Electroless Nickel & Immersion Gold) which is connected with gold wire by ultrasonic bonding. Therefore we have looked for proper plating chemicals which can make surface endure Ultrasonic wire bonding shock.

( * The thickness of electroless nickel layer should be 5 to 8 µ and the thickness of gold layer should be about 0.15 µ)

I think that electroless nickel layer should have ductility or fine grains in order to endure ultrasonic bonding shock.

If you have any idea or information with regard to ductility and ultrasonic bondability of electroless nickel plating & immersion gold ,please help us.

Thanks & regards.

Hyun Soo Park
Gunpo-Shi ,Kyeonggi-Do, Republic of Korea

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Dear Mr. Park,

Can you provide photos of the cracked pad?

The surface is fairly smooth, I would be more concerned about the ductility and elongation of the electroless nickel, which could be tested by some standard method (ASTM, perhaps?)

  
Tom Pullizzi
Falls Township, Pennsylvania
2000