Letter 10000

Need Tight Nickel Plating Thickness Tolerance 

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I am working with various electro-plating companies to coat nickel on thin sheets of material that are roughly 48" x 48" x 0.06" thick. Aim is to get 200 (+100, -0) microinches of plating thickness. Edges are masked to prevent material build-up. Nevertheless, I'm told thickness variation can be as much as 400 microinches across the entire surface.

Is this reasonable?

Can this be controlled better (+/- 50 microinches)?

How can one accurately measure the variation non-destructively?

David K [name deleted for privacy]
- Columbus, Ohio, USA

It would take thieves and shields to do it and that can be a large pain. Simplest is to just use electroless nickel. Costs more, but is superior in nearly every way.

James Watts
- Florida

One problem with electroless nickel is that its melting point is below 1000 C ---bad news for me. I've got to have the electrolytic. So...my original question, can you control it to +/- 50 microinches?

Suggestions for sources?

David K [name deleted for privacy]
- Columbus, Ohio, USA

Dave:

It can be done by means of a time consuming preparation work of anode placing and thieves (something most platers just hate) and a good help from statistical laws (cross fingers). There are two other ways also expensive but worth exploring. Electroless nickel- boron (melting point is 1,080C) and over plating and then grinding your actual electro-nickel.

Good luck,

Guillermo Marrufo
Monterrey, NL, Mexico

I agree. Thieves and shields take a lot of trial and error. This will cost a chunk of change! Virtually any good plating book will have a chapter on this subject. AESF has a neat pamphlet for sale on this subject.

What causes it is a science. How to correct it is an art.

James Watts
- FL

The thickness variation is often a problem resolved by subsequent grinding. When we use the Chemical Vapor Deposition process to grow nickel shapes, or coatings, on complex pieces, the variation can be only as close as +/- 0.005 inch. The main variable is the uniformity of heating of the substrate (to 350 deg.F) for the CVD process, but the nickel does grow very fast - at a rate of 0.010 inch per hour.

Cheers,

Mick O'Meara
- Toronto, Canada

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