epoxy instead of solder?
 

Has anyone tried Masterbonds conductive epoxy for attaching SMT
components to a printed circuit board?

Seems like a great idea, especially if it works well::

T

On Wed, 05 Oct 2005 16:10:40 -0400, TRABEM wrote:

Has anyone tried Masterbonds conductive epoxy for attaching SMT
components to a printed circuit board?

Seems like a great idea, especially if it works well::

---
Aside from the resistivity of the epoxy, the largest problem I see
is throughput. That is, where are you going to store all those
boards while the epoxy is curing?

Plus, it makes it really messy for the salvagers/recyclers.

--
John Fields
Professional Circuit Designer

Hello John,

Aside from the resistivity of the epoxy, the largest problem I see
is throughput. That is, where are you going to store all those
boards while the epoxy is curing?

Then there is the stench that most epoxies let off. Mostly of the not so
healthy kind.

Regards, Joerg

http://www.analogconsultants.com

In article , TRABEM
says...

Has anyone tried Masterbonds conductive epoxy for attaching SMT
components to a printed circuit board?

Seems like a great idea, especially if it works well::

Not really. Consider the angle of serviceability. It's easy enough
to use a 'HoTweezer' station to replace a bad chip component secured
with solder. It's darn near impossible to replace the same component if
secured with Epoxy.

Also, I'm not convinced that "conductive" Epoxy really is. I'd
want to see some real numbers on resistance per cm/squared on the stuff
before I even consider it for any sort of repair work.

Any job worth doing is worth doing right. If you're trying to
attach surface-mount components, invest in the proper
soldering/desoldering equipment instead of looking for impractical
shortcuts. It may cost more at the get-go, but it'll cost a lot less in
the long run.

Keep the peace(es).


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"

John Fields wrote:

On Wed, 05 Oct 2005 16:10:40 -0400, TRABEM wrote:


Has anyone tried Masterbonds conductive epoxy for attaching SMT
components to a printed circuit board?

Seems like a great idea, especially if it works well::


---
Aside from the resistivity of the epoxy, the largest problem I see
is throughput. That is, where are you going to store all those
boards while the epoxy is curing?

Plus, it makes it really messy for the salvagers/recyclers.

I do not know about Masterbonds conductive epoxy(ies), but i have
used silver conductive epoxy.
1) EXPENSIVE, 2) good for short-term and medium-term repair, but no
where as reliable as a solder connection.

Dr. Anton T. Squeegee wrote:

In article , TRABEM
says...


Has anyone tried Masterbonds conductive epoxy for attaching SMT
components to a printed circuit board?

Seems like a great idea, especially if it works well::


Not really. Consider the angle of serviceability. It's easy enough
to use a 'HoTweezer' station to replace a bad chip component secured
with solder. It's darn near impossible to replace the same component if
secured with Epoxy.

Also, I'm not convinced that "conductive" Epoxy really is. I'd
want to see some real numbers on resistance per cm/squared on the stuff
before I even consider it for any sort of repair work.

Any job worth doing is worth doing right. If you're trying to
attach surface-mount components, invest in the proper
soldering/desoldering equipment instead of looking for impractical
shortcuts. It may cost more at the get-go, but it'll cost a lot less in
the long run.

Keep the peace(es).


The silver conductive epoxy is extremely conductive, and even tho i
never measuresd the resistivity, i would wager that it is better than
copper if used properly.

Robert Baer wrote:

The silver conductive epoxy is extremely conductive, and even tho i
never measuresd the resistivity, i would wager that it is better than
copper if used properly.

Here are some examples of silver epoxies:
http://news.thomasnet.com/fullstory/460221
10^-3 ohm cm

http://www.mgchemicals.com/products/8331.html
2*10^-2 ohm cm

http://bondline.net/datasheets/2072.pdf
4*10^-4 ohm cm

http://bondline.net/datasheets/2080.pdf
5*10^-3 ohm cm

http://bondline.net/datasheets/2111.pdf
2*10^-4 ohm cm

http://bondline.net/datasheets/2120.pdf
5*10^-3 ohm cm

Copper:
http://www.lehighton.com/AppNotes/Cu...llization.html
1.68*10^-6 ohm cm

According to these sources, copper is about 100 to 10,000 times as
conductive as silver filled epoxy.

Has anyone tried Masterbonds conductive epoxy for
attaching SMT components to a printed circuit board?
Seems like a great idea, especially if it works well::

Sounds like a terrible idea. The surface tension of solder and the
solder mask/PCB landing on the circuit board interact very nicely to
make sure that a blob of solder and the part itself stays on exactly
the right spot when you solder on a SMT component (either hand
soldering or toaster-oven style). None of that is working to your
advantage when you use epoxy.

Hand-soldering even fine-pitch (0.5mm) SMT stuff is not a big deal to
do by hand with even primitive (e.g. just a weller soldering iron and a
fine-tip point and some solder wick) tools. BGA's will require a
toaster oven though :-).

Tim.

It is done in special circumstances, but not that often. SMT passives
are available with different termination platings/coatings for such an
application, but they are harder to come by. It won't work as well if
you use devices with terminations intended for soldering.

The 3M conductive adhesives like the 9703 work well. Not sure how they do it
but it conducts in the Z axis ( thru the adhesive ) but not accross the
surface direction ( X & Y axis ). It's a pressure sensitive transfer
adhesive ( tape that you stick on then peel off the paper carrier leaving
the adhesive behind)

X-Y axis Insulation Resistance = 3.4 x 10 to the 14th Ohms/square
Z axis Contact Resistance = 1.25 milliOhm-in2

Pretty neat stuff!

Ron H.




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