Hello Peter,
You may want to visit Bryte Technologies (http://www.brytetech.com/) and
look at the adhesives specifically designed for radomes, etc. I have used
the 1502-EX, cyanate ester adhesive, on several applications involving
teflon bonding. One drawback is the time/temp cure of the material, which
is variable dependent of course on your application, but 121°C for 5 hours
seemed better suited for the variables involved with my applications. The
"to-be-bonded" surfaces were prepared with a primer, Dow Corning 1205, which
was used to increase the bondability of the teflon -- tested and proved to
increase the shear strength of the bond by 20%.
Just my $.02.
Good luck.
Steve Sauer
Sr. Mfg Engineer
Northrop Grumman, Xetron
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Wednesday, January 29, 2003 9:24 PM
To: [log in to unmask]
Subject: [TN] Adhesive for Teflon
'Morning, All
This object of this problem is not a board, but a wave guide with a (PTFE?)
teflon dome bonded to it - or at least to what looks like glass fibre
cladding on the waveguide flange. The guide is pressurised to 28 p.s.i. at
1 atmosphere.
Wall thickness of the dome is approx 10 mils. The flange that it's bonded
to measures about 2.75" x 1.5" x 0.4" thick and there are traces of a
yellow-coloured material, which I take to be the adhesive that bonds the
teflon dome to the flange. I cannot be sure, though.
The problem now is that the dome has separated from the flange along one
side so that it can no longer be pressurised. It's a very expensive
component, and worth repairing if possible. Does any one of you great folks
know of an adhesive and method of application that would be effective in
rebonding the teflon back onto the GF-coated flange? Obviously the adhesive
must stick well to low-energy surfaces, but additonally it must have good
tensile adhesion, since the internal pressure of the dome will tend to
"peel" the rectangular wall away from the flange.
Any help will be greatly appreciated. At present, components that have been
'punctured' like this are just thrown away and replaced with new ones, and
there may be a very good reason for this - like it's not possible to remove
the dome, clean it up and bond it back in place again, but I thought I
would ask anyway.
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
