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How to plate uniform thin Nickel into photoresist pattern

June 30, 2011

Hi, we have a project that requires around 1 µm thick Ni (I know it is thin) into a patterned photoresist. Basically, we expect the plated Ni to be a 50 mm bar with cross-section of 5 µm width by 1 µm height. The 5 µm will be confined by resist pattern. So I need to get uniform 1 µm height.

Our sample is a glass slice (2 by 3 inch)with Ni layer coated on one side (0.05 um, as conductive layer). We have some photoresist pattern (1.5 µm thick)on top of the seed layer and would like to Electroless plate Ni (we expect around 1.0 um) onto the region where photoresist is absent.

Should I go electroplating or E'less plating? I used to use electroplating, but the X-section is not good with a center bump out shape. Will electroless plating help?

Xiaohui Lin
university researcher - Austin, Texas, US

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July 12, 2011

This is trick worth trying.

Place the anode flat on the bottom of the plating cell with the lead to it insulated.
Suspend the part in the solution face up above it allowing a reasonable clearance all round and say an inch below the surface.
Plating at about 1 amp /sq dm, your tiny surface area may make controlling the current a major consideration.

If you decide to try Electroless Nickel - two points. It may be difficult to control in the small volume you will be using. And remember that your deposit is not nickel. It is commonly a nickel/phosphorus alloy which may not have the properties you are looking for.

Geoff Smith
Hampshire, England