Can selant foam chemicals damage electronic boards?

Thread View: sci.electronics.repair

5 messages

[T] Back to Threads [V] Tree View [G] Group Articles

5 total messages Started by miguel@ldgo.colu Tue, 05 Jul 1994 16:00

Author: miguel@ldgo.colu
Date: Tue, 05 Jul 1994 16:00

44 lines
1648 bytes

Hi there!

        I'm planning to use an expanding foam sealant (spray form) to
make some forms that will hold electronic boards.  These electronic
boards are located in a hermetically sealed (0.5 atmosphere of
pressure) pressure vessel for uninterrupted periods of time longer
than a year without reopening or venting.

        My concern is that some of the chemical components used in
this foam may affect the electronic boards or the components used.
The foam will not come in direct contact with the boards, but the
remaining vapors or solvents eventually will.

        The foam sealant will be first cured for at least 48 hours and
then submitted to vacuum before use, to minimize the remaining
solvents and spray carriers used during injection.

        The foam sealant is available commercially from hardware
stores for home use to insulate and stop drafts, block radon gas and
seal out pests.

The listed contents of the foam are:
        Polymeric Isocyanate
        Polyol Resin
        Hydrochlorofluorocarbons.
        Specifically, it indicates no urea formaldehyde.

        Additionally, Underwriters Laboratories Inc., has tested the
material surface burning characteristics (R-13655), applied to
inorganic reinforced cement board.  However, no tests have been
performed on other materials, i.e.: plastics and others commonly used
in the fabrication of electronic components.

        Does anybody know any damaging effects these chemicals may
have on electronic components?
        Any comments are welcome!

Thank you.
Miguel Maccio.
Lamont-Doherty Earth Observatory

Please e-mail responses to:  'miguel@ldeo.columbia.edu'

Re: Can selant foam chemicals damage electronic boards?

Author: jlundgre@news.kn
Date: Tue, 05 Jul 1994 19:09

6 lines
227 bytes

I haven't the foggiest about solvent reaction with the PC board, but you
can prevent oxidation by using nitrogen or other oxygen free atmosphere
to minimize oxidation.  Since it will be sealed, Why not?  Maybe even CO2.

--

Re: Can selant foam chemicals damage electronic boards?

Author: dbrewste@netcom.
Date: Wed, 06 Jul 1994 01:30

17 lines
717 bytes

John Lundgren (jlundgre@news.kn.PacBell.COM) wrote:
: I haven't the foggiest about solvent reaction with the PC board, but you
: can prevent oxidation by using nitrogen or other oxygen free atmosphere
: to minimize oxidation.  Since it will be sealed, Why not?  Maybe even CO2.

Now I know why my phone line is so noisy (:*)

Nitrogen is a waste of time unless you are going to seal the container
and keep it at a slight overpressure...and monitor its condition.
Nitrogen also won't do any good if the sealant gives off certain products.
CO2 isn't inert in the presence of any moisture.

some sealants outgas corrosive gasses.
--
Dick Brewster                                             dbrewste@netcom.com

Re: Can selant foam chemicals damage electronic boards?

Author: mlanders@netcom.
Date: Wed, 06 Jul 1994 02:37

10 lines
435 bytes

How about sealing the board with one of the silicone compounds before
putting it in the container? BTW, any heat build-up might cause out
gassing from the foam.

--
        Mark Landers          |     The object of opening the mind,
                              |        as of opening the mouth,
     mlanders@netcom.com      | is to close it again on something solid
                              |           - G. K. Chesterton -

Re: Can selant foam chemicals damage electronic boards?

Author: dbrewste@netcom.
Date: Wed, 06 Jul 1994 05:18

11 lines
417 bytes

Mark Landers (mlanders@netcom.com) wrote:
: How about sealing the board with one of the silicone compounds before
: putting it in the container? BTW, any heat build-up might cause out
: gassing from the foam.

just be sure its not one of the silicon compounds that outgases corrosive
products.  Get one made for electronics work.
--
Dick Brewster                                             dbrewste@netcom.com

Thread Navigation

This is a paginated view of messages in the thread with full content displayed inline.

Messages are displayed in chronological order, with the original post highlighted in green.

Use pagination controls to navigate through all messages in large threads.

Back to All Threads