Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!decwrl!infopiz!lupine!sheridan!petes
From: petes@sheridan.NCD.COM (Peter C. Simpson)
Newsgroups: sci.electronics
Subject: Re: Need information on Cu,Ni,Cr plating of 1m dia hemisphere
Message-ID: <3721@lupine.NCD.COM>
Date: 5 Feb 91 20:33:39 GMT
References: <2867@oucsace.cs.OHIOU.EDU>
Sender: news@NCD.COM
Reply-To: petes@sheridan.NCD.COM (Peter C. Simpson)
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Two points - immersion of your gas filled balloon in a plating bath of 
higher density will destroy its shericity.  You would need to fill it with
something of equal density.  

Also, electroless plating is normally used to plate non-conductive surfaces.
It is commonly used to plate plastic computer enclosures, for instance.  The
process involves a bath in an etchant to activate the plastic surface,
then a series of plating and rinse baths.  Plating thickness is entirely
a function of time, but your thicknesses will be financially impractical to
achieve.  40 millionths of an inch of copper will take about 15 minutes, so
you're talking about one month for 1/8 inch.  The standard process is to plate
nickel overthe copper for corrosion protection.  Standard plating thicknesses 
for shielding applications would be 40 uI copper, 10 uI nickel.  

I guess that if I were trying to do this, I would build up a thickwalled hollow
sphere out of ABS or some other platable plastic, and then put a much thinner
coating than your 1/8 inch on.  Finally, you might look at the plastic ball/
electroless shielding to generate a thinly coated sphere, then use this
conductive
part for a faster depositing electrolytic process.

I can recommend sources for electroless platers, if you are interested.


                                           Peter Simpson
                                           Network Computing Devices