I was assuming, in my early response that no one, in their right mind,
would even dream of using the RTVs based on an acetic acid reaction on
an electronics assembly. If the RTV smells sharp or vinegary before
curing, you are already in DEEP trouble.

Brian

Ofer Cohen wrote:

> Most RTV compounds will out gas mild acid along the life cycle. Closing is under coating may cause the acid to attack the RTV near components and PCB.
>
> Ofer Cohen
> Manager
> Quality Assurance, Reliability and Production Technologies
> Seabridge Ltd. - A Siemens Company
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of David Douthit
> Sent: Thursday, February 26, 2004 17:57
> To: [log in to unmask]
> Subject: Re: [TN] Conformal coat over RTV?
>
>
> Mark,
>
> DON'T!!!
>
> The fact that the components are "sensitive" combined with the fact that
> the coating will not bond properly results in an environmental exposure.
>
> Why RTV staking, cost? Use epoxy!
>
> Trying to save money no matter how much it costs is very expensive!
>
> David A. Douthit
> Manager
> LoCan LLC
>
> Mark Charlton wrote:
>
>
>>My learned and esteemed colleagues,
>>
>>One of our customers has requested that we conformal coat over a DOW 3145
>>RTV adhesive used to stake some sensitive components.  The specified coating
>>material is MS470-N, a urethane product.
>>
>>Is this a standard practice (to coat over RTV)?  We have always conformal
>>coated the PCA and then staked the components using the RTV.  Our CC vendor
>>isn't too pleased with this request.
>>
>>Mark Charlton
>>
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>>
>>
>>
>
>
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