I just opened up this coating question to get Graham cranked up, but now
that we're talking about it, parylene can be reworked to a limited degree.
We have successfully removed the coating in isolated areas like where a
component had to be replaced by scribing the perimeter of the area with a
razor knife and then slowly peeling the coating off the board with tweezers.
It's time-consuming, but sometimes necessary to save expensive space
hardware. The assembly could then be re-coated as original (except the film
would be double thick in the other, non-reworked areas). You are correct,
though, that the entire coating film can not be removed. Because of that
limitation, we use 2-part polyurethane coating applied by spray in 2-4 mil
thickness. We found that thicker coats would fillet too much on small glass
components like diodes and they would crack like a hot dog bun when exposed
to low-temp (-36 deg. F)thermal cycles.
----Rainer
-----Original Message-----
From: Hinners Hans Civ WRALC/LYPME [mailto:[log in to unmask]]
Sent: Wednesday, January 19, 2000 6:13 PM
To: [log in to unmask]
Subject: Re: [TN] Postings
Hey Rainer, Graham and all,
If it's going into space, I guess you don't have to worry about rework.
We're looking into both. Somebody found a polyurethane coating that has a
chemical stripper - news to the folks around here and much easier to rework
than mechanically removing if the coating goes where it shouldn't during
application.
Hey Graham - how come Concoat doesn't have a US rep?
Hans
~~~~~~~~
Hans M. Hinners
Materials (& Process!) Engineer
Warner Robins - Air Logistics Center/Avionics Production Division
Manufacturing Branch (LYPME)
380 Second Street, Suite 104 (Building 640)
Robins AFB, GA 31098-1638
912-926-1970 (Voice) 468 - 1970 (DSN) 912-926-7164 (Fax)
[log in to unmask]
> -----Original Message-----
> From: Blomberg, Rainer (FL51) [SMTP:[log in to unmask]]
> Sent: Tuesday, January 18, 2000 01:53
> To: [log in to unmask]
> Subject: Re: [TN] Postings
>
> OK,
> You're still on-line.
> What do you think about parylene coating small boards approx... 3'' dia.
> with SMT components? Or would it be better to spray polyurethane?
>
> R. G. Blomberg
> Honeywell - Space Systems
> Staff Production Engineer
> (727) 539-5534 voice
> 727-539-4469 Fax
> [log in to unmask]
>
> -----Original Message-----
> From: Graham Naisbitt [mailto:[log in to unmask]]
> Sent: Tuesday, January 18, 2000 11:24 AM
> To: [log in to unmask]
> Subject: [TN] Postings
>
>
> Is there something wrong out there? Does nobody love me any more? I
> am bereft of my daily Techy stuff
>
> Please advise if I have to re-subscribe
>
> Regards,
> Graham Naisbitt
>
> [log in to unmask] <mailto:[log in to unmask]>
>
> WEB: <http://www.concoat.co.uk>
>
> CONCOAT Ltd
> Alasan House, Albany Park
> CAMBERLEY GU15 2PL UK
>
> Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
>
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