At 7:12 AM -0400 10/23/96, CINDY KEMP ORLANDO ISC *8-306-6873 wrote:

>Technet,
>
>I'm forwarding this from a colleague.
>
>Cindy Kemp
>Lockheed Martin
>Orlando, FL
>*******************************************************************************
>
>From: [log in to unmask]
>Date: Tue, 22 Oct 96 16:35:22 EDT
>Message-Id: <[log in to unmask]>
>To: [log in to unmask]
>Subject: pwb-cca : conformal coating
>Sender: [log in to unmask]
>Precedence: bulk
>
>hi group;
>
>We are finding that in designs using conformal coating (UR) over plastic parts
>that the cc is dewetting on the parts.
>
>Question - is this seen as a problem ?
>
>I am proposing that a note should be added to our designs as follows:
>
>	CONFORMAL COAT DEWETTING ON PLASTIC ENCAPSULATED MICROCIRCUIT
>	COMPONENT BODY IS ACCEPTABLE.
>
>If there is a better way please let me here from you.
>
>What is the real would doing ?
>
>
>			thanx; Skip Greb

Cindy,

We have this same issue with plastic ICs.  As long as the conformal coating
encapsulates the metallization associated with the plastic part, we
consider it a cosmetic issue only.  The de-wetting is probably due to the
presence of mold release on the devices, which is not removed during your
cleaning processes.  We see it occur only with certain devices.

Our cc system is a urethane and our end application is a military, ground
mobile environment.  We've run boards with dewetted cc through all the
standard mil qual tests and haven't seen any problems associated with it.

-Gregg



_________________________________________________________
Gregg Klawson                        tel: +1.508.880.1822
GTE Government Systems Corp          fax: +1.508.880.4891
Taunton, Massachusetts USA         email:  [log in to unmask]


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