> Date: Mon, 19 Jan 2004 22:17:43 +0900
> From: "Choe,S-H" 
> Subject: [mems-talk] Rhodium plating
> Hello. I am now trying to electroplate Rhodium.
> It is said that Rhodium is well suited for parts such as sliding
electrical
> contancts that require protection from corrosion, and it is the hardest
> of all of the precious metals.
>
> But, I could not find the plating solutions that are useful for
> micromachining
> I found that MIL-R-46085 shows the specification for the Rhodium plating.
>
> If you have any information on Rhodium plating, please let me know that.
> Choe,Seong-Hun
> Esashi Lab, Tohoku University, Japan
> E-Mail: [email protected]

Dear Choe,

I have used Rhodium S-Less from Technic (www.technic.com) to microfabricate
interdigitated electrodes for humidity sensing onto a silicon wafer with 500
nm themal oxide layer. I tried both plating through a photoresist pattern
onto a Ti/Au seed layer, and also electrolytic etching of the Rh layer
through a photoresist pattern with sulfuric acid. In the end I got the first
method working sooner, but I think the second would have been OK too.

My electrode digits were 50 um wide by 2 mm long. i had a lot of trouble
with them peeling off, which I attribute to stress in the rhodium, rather
than poor adhesion. That's because when they peeled, they took the
underlying adhesion layers with them. I had to play with low duty cycle
pulsed plated, and the bath temperature. You can e-mail me for more details.

Best regards,
Jordan