[sci.electronics] Silver Plating, Need Ernie

ornitz@kodak.UUCP (Barry Ornitz) (08/09/89)

Before you read the signature and say: "Ah ha, who better than a Kodak person
to talk about silver chemistry" let me add that the chemicals division is
(organic) chemicals, plastics, and fibers.  That said.....

The simplest method of silver plating small parts around the home is to use an
electroless silver plating method.  The application to tank coils and VHF/UHF
cavities is ideal.  Electroless silver produces very thin coatings, but these
are all that are usually necessary.  I have found very little difference
between silver-plated coils/cavities compared to shiny copper in respect to
efficiency or Q.  However, as both surfaces tarnish, the silver plated surface
will retain its high Q much longer.  Electroless silver will provide just
enough silver on the surface of copper or brass to prevent the corrosion of
the base metal.  Heavy silver plate might be slightly better in electrical
performance, but the effort (and cost and complexity) is hardly worth it.

One of the easiest electroless silver plating compounds is made by a company
called Cool-Amp.  This is a powder that when moistened slightly and rubbed on
clean copper or brass produces a nice shiny silver coating.  Several months ago
a pound cost about $70.  Don't let the price scare you because a pound will
go a long, long way.  It will probably last your whole ham club many years if
you use it properly.  I have made something similar using silver chloride,
sodium chloride, and potassium tartrate but the Cool-Amp works better.  After
buffing the copper surface with steel wool, or even better - a Scothbrite
scouring pad, rub the slightly moistened powder on the copper using a paper
towel.  Make the powder too wet and it doesn't work!  You might consider
using rubber gloves unless you like having green edges on your fingernails.
Finish off the plating with a rinse of clean water.  After the object is dry,
a coat of clear acryllic spray will help to keep the surface shiny (acryllic
plastics also have low dielectric losses).
          
                                 73 de WA4VZQ, Barry
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|  ___  ________  |
| |  / /        | |  Dr. Barry L. Ornitz  UUCP:..rutgers!rochester!kodak!ornitz
| | / /         | |  Eastman Kodak Company
| |< < K O D A K| |  Eastman Chemicals Division Research Laboratories
| | \ \         | |  P. O. Box 1972
| |__\ \________| |  Kingsport, TN  37662       615/229-4904
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