Metal finishing Q&As since 1989

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The reducing of the rate electrodeposition of nickel alloy

The electrodeposition rate of the nickel alloy was reduced in 5 times on gold pattern in photoresist in comparison with a gold flat sample. The increasing of the temperature from 20 up to 50 °C and reducing of the distance between the anode and the cathode of results didn't give the result. The pattern is a net of grooves with depth 25 micron, width - 15 micron, length - 1.4 mm. The anode and cathode had the same area and pattern in the photoresist, the distance between of their - 4 mm.

[last name deleted for privacy by Editor]
R&D - Moscow, Russia
2004

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I think we need your process details, such as the current density you are using, what the nickel alloy is and everything about the electrolyte. I suspect you may be using a too higher cathodic current density and causing hydrogen to be discharged from the surface. However, more information will help us.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004

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If I understand you right you are using a anode that has the same resist pattern on it as the part you want to plate. If this is so use a uncovered nickel anode, this will probably solve your Problem.

Regards,

Marcus Hahn
- Lucerne, Switzerland
2004

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2004

I have used for electrodeposition of the binary nickel alloy j=10 mA/sq.cm and pulse cycle ton/toff=2/8 ms. The nickel is more noble metal in my alloy because I haven't increase the current density for increasing of the rate of electrodeposition of patterned wafer as under the increasing j the concentration more noble component in my alloy -Ni decreases together with the hardness but I must support the last by constant.

Additionally I found the loss current through the porosity of the photoresist as the wafer with conductive underlayer and covered by a photoresist without open metal surface was polarized under the working current density. But I haven't found on the bottom of the photoresist pinholes - on the underlayer TiW the Ni deposit. Because I don't understand the direction of the loss current - may be the hydrogen evolution on the TiW of the with lower overpotential and the formation Ti hydride.

[last name deleted for privacy by Editor]
R&D - Moscow, Russia