At 08:47 AM 9/9/96 EDT, you wrote:
>  I was wondering if someone has some information on the environmental impact
>of the parylene process.  Are there any emissions evolved and if so what are
>their typical concentrations?  I realize that some parylene may get trapped
>in the cold trap and will have to be disposed of by landfill.  How much waste
>is generated per cycle?
>  Also, I am told that substrates for parylene coating are first washed with
>de-ionized water and then treated with an adhesion enhancing solution.  In
>SCS's literature the enhancer is a gas while most companies use a liquid
>enhancer.  Are there any advantages/disadvantages with using either one?
>  Is humidity a problem for parylene?  Can humidty get trapped between the
>coating and the board which would cause corrosion?
>
>                   My thanks in advance.
>
>Reply:
>Per Ben Guthrie, an engineer in our area very familiar with Parylene:

Parylene is an excellent moisture barrier. Also, because it is applied using
a vacuum deposition process, 
moisture under the parylene is not likely. A pre-bake would take care of any
such concerns.
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Jeffery L. Hempton              Phone: (219) 429-7335   Fax: (219) 429-4688
Hughes Defense Communications                           Mail Stop: 25-31
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