Only a two part epoxy will meet your needs. Devcon makes a 1233 5 min epoxy as does Loctite. Some of the dual tube dispensers automatically mix the epoxy through the 24 turn nozzle tip, with others you simply mix. The general rule is a 15-30 minute will yield a stronger bond. However you can speed up the curing process to about 15 minutes in an 120F oven in most cases for epoxies designed for circuit board repair.
----- Original Message -----
From: "Peter Swanson" <[log in to unmask]>
To: [log in to unmask]
Sent: Monday, March 9, 2009 1:10:52 PM GMT -05:00 US/Canada Eastern
Subject: Re: [TN] Coatings, epoxies, etc crash course
Genny,
>>> I am looking for a 1-part solution for quick touch-ups, that will
hold up.
I would tend to suggest an epoxy to mend your track cut with weave
exposure. Epoxy is what was used to manufacture it in the first place,
so you get all sorts of consistencies (thermal, electrical, etc). If you
are going to be doing any soldering near the repair, you may need the
temperature resistance which epoxy gives you.
The problem with looking for a 1-part is that this has to cure or harden
somehow. The candidates include:
- UV/visible light - OK, but you need line of sight
- cyanoacrylate (superglue) - useful for wire tacking and
component retention, low temp resistance compared to others, not sure I
would use it for a structural pcb repair. Unless it is interfacial, you
may need an activator to get cure
- anaerobic - like threadlockers - won't work here
- hot melt
- RTV silicone - will be soft, rather than hard
- solvented system which dries rather than cures - not much
cross-linking so not very resistant
- 1-part epoxy which cures with heat - usually need 125 deg C or
more for cure, need fridge or frozen storage
I am not sure there are any other basic 1-part candidates, but if anyone
thinks of any, please let me know!
If you go for a two part epoxy and only use intermittently, buy it in
small twin-packs to minimise waste and handling. Use in conjunction with
a small bench heat lamp to speed up cure.
>>> I am also looking for general educational sources on electronic
related materials and chemicals.
For adhesives, try:
http://www.omnexus4adhesives.com
http://www.adhesivestoolkit.com/Introduction.xtp
Regards,
Peter
--------------------------------------------------------
Peter Swanson [log in to unmask]
INTERTRONICS http://www.intertronics.co.uk
Tel: +44 1865 842842 Oxfordshire, England
INTERTRONICS is dedicated to providing quality material, consumable
and equipment solutions to the high technology, high performance
assembly industries, incorporating outstanding levels of technical
support and customer service.
Read our news! http://www.intertronics.co.uk/blog/blog.htm
INTERTRONICS is the trading name of Cygnet Electronics Ltd,
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ENGLAND.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: 09 March 2009 16:19
To: [log in to unmask]
Subject: Re: [TN] Coatings, epoxies, etc crash course
We use that Armstrong material already. Armstrong is from RTG (Resin
Technology Group). I have had a great deal of difficulty finding out
any detailed information about RTG and Armstrong. Resintechgroup.com
redirects to Henkelna.com. I find Henkel's site to be fairly useless to
get any meaningful detailed technical information.
It is a 2-part epoxy. For PCB repairs it works great. But it is not
something that can be used for quick in-line touch-ups.
I am looking for a 1-part solution for quick touch-ups, that will hold
up.
I am also looking for general educational sources on electronic related
materials and chemicals. Maybe that is a lot to ask, but how do you
know when to look for an epoxy? When do you need an acrylic? When
should you consider a silicone based material?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey
(EHCOE)
Sent: March 9, 2009 10:03 AM
To: [log in to unmask]
Subject: Re: [TN] Coatings, epoxies, etc crash course
Richard,
I agree with you on the Eccobond and Resiweld having qualified them a
long time ago, but I am not aware of Armstrong C7. If you say it does a
bang-up job, I would be concerned since it's 3 levels higher than C4.
Seriously though does it pass for Aerospace work (outgassing, corrosion,
compatibility issues)? Let me know, as I don't want to appear as stuck
in the past.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, March 09, 2009 5:01 AM
To: [log in to unmask]
Subject: Re: [TN] Coatings, epoxies, etc crash course
Armstrong C7 with Hardener "W".
Resiweld
Eccobond
These all work well for sealing board cuts or damaged FR-4, but I like
the Armstrong best.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: Friday, March 06, 2009 10:35 AM
To: [log in to unmask]
Subject: [TN] Coatings, epoxies, etc crash course
Hello all,
I do a lot of component and material sourcing, crossing, and spec'ing.
Probably the area I struggle with the most is the materials, like
epoxies for board repairs, or adhesives, or sealants, cleaners, etc
etc,...I did electrical engineering, not chemical.
Is there any good resource place to get a handle on when you want an
acrylic versus an epoxy, or silicone, or ... basic properties, what
environment they are needed for, etc.
A specific sourcing question I have right now - for challenging board
repairs we use specially trained operators in a rework cell that use a
2-part epoxy to repair FR4. One product has a track cut, that usually
causes weave exposure, that happens on every board on the line to allow
for different configurations, and they want a way to protect it
adequately with a 1-part quick curing material without sending it to the
rework cell. We've tried those conformal coat pens, and they can be
washed right off the board. Any suggestions?
Genny
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