Masking Nickel Plate

I'm completely guessing here, but it may get you on the right track.

I'm thinking along the lines of sheetrock mud. I think you call it spackling in the UK. Something along those lines that could be applied, heat won't bother it, you could fill the fine slots with it, and simply rinse it off with water when you're done.

I don't know anything about this sort of thing, but, I believe that Nickel plating needs to be done at high temperature, which could make many masking techniques fail.

I did a search for Kynar tape which is used to mask gold edge connectors on PCBs when flow soldering, and, found this stuff:-

http://www.mocap.co.uk/high-temp-poly-tapes.html

It might be worth talking to them.

Here's another one:

http://www.intertronics.co.uk/products/xpcbass.htm

http://www.intertronics.co.uk/products/cint701.htm

3M makes a line of platers tapes that I've used before. I don't know if they would work for you.

Here's two:

1. Circuit Plating Tape 1280: 3M™ Circuit Plating Tape 1280
   
2. Greenback Circuit Plating Tape 851: 3M™ Greenback Circuit Plating ...

There are masks available for nickel but the ones I have seen are lacquers & need to be removed by abrasion. My concern is for the delicate structure in the centre of our component. We use adhesive tape masks when we evaporate chrome & copper onto optics & have found it quite hard to completely remove the adhesive.

Looks like you are going to earn your pay on this one.

Doesn't sound too easy.

Good luck.

It's a possibility. There are conflicting process requirements, the slots are laser cut & have to be done by holding a whole sheet of moly. The nickel could be applied to the whole sheet before cutting. I know that the chamber used for the other coating process is quite small & will only hold a few components at a time. I would have to check if there is likely to be any adverse chemical reaction to the nickel but it's a path worth investigating.

You might consider using a photo-resist like the semiconductor industry uses. It can be spun or sprayed onto the moly, exposed to light through a mask, and washed away where you want the plating. After plating, the remaining resist that protected the slots can be removed chemically or in a plasma cleaner.

Looks like the method we will try is to nickel plate the whole moly sheet first. Still not sure if the nickel will interfere with the later process applied to the laser cut slots but we only need the later coating on the angled faces of the slots so it won't matter if it does not take on the sheet faces. It will probably take a couple of months to get through all the processes but I'll try to remember to post the results.

As always, thanks for all the good advice.