John Woodgate wrote:
I read in sci.electronics.design that wrote:


Just another point of reference. From:
http://www.efunda.com/materials/solders/tin_lead.cfm
Eutectic tin lead solder has a conductivity of about 1.44*10^-5 ohm cm,
or 8.5 times that of copper.

resistivity, not conductivity.

Thank you.

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.

On 6 Oct 2005 09:59:53 -0700, "w2aew" wrote:
Wow,

Despite the less than stellar support for the concept, I'm going to go
ahead and try it anyway. I found a company in CA that makes 2
different types of epoxy, just for this purpose. The guy says it will
work and the curing time is short and not temperature sensitive
(unlike solder paste).

He's sensing me samples of both types although the spec's aren't
available due to translation problems (the stuff is imported, and no
English translation of the spec sheets exists).

I'm going to give it a try on through hole components first, then will
play with some smt once I get some experience under my belt.

I'll post a message with the results back here is there is any
interest.

Regards,

T

I read in sci.electronics.design that TRABEM wrote (in
) about 'epoxy instead of
solder?', on Sat, 8 Oct 2005:
He's sensing me samples of both types although the spec's aren't
available due to translation problems (the stuff is imported, and no
English translation of the spec sheets exists).

What language(s) is it in?
--
Regards, John Woodgate, OOO - Own Opinions Only.
If everything has been designed, a god designed evolution by natural selection.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

TRABEM wrote:
He's sensing me samples of both types although the spec's aren't
available due to translation problems (the stuff is imported, and no
English translation of the spec sheets exists).

Hopefully they've taken the time to write / translate / send you an MSDS
for it...

Richard

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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Ron H wrote:
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)
I have a roll of that. Very pricey. It contains lots of short bits
of very fine copper wire precisely aligned through the thickness of
the adhesive gel. The wires do not contact each other, so there is no
conductive path along the gel.

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!

Definitely. Sort of the dual of enameled wire. Conducts only at
right angles to the length.

On Thu, 6 Oct 2005 19:35:36 -0500, "Ron H" wrote:

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.


Sounds VERY interesting! I have some clients that need to mount
components that can't stand the heat of soldering. The only problem
might be "tenacity"... how much "shake, rattle and roll" can it take?

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

Jim Thompson wrote:
On Thu, 6 Oct 2005 19:35:36 -0500, "Ron H" wrote:


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.



Sounds VERY interesting! I have some clients that need to mount
components that can't stand the heat of soldering. The only problem
might be "tenacity"... how much "shake, rattle and roll" can it take?

Its glorifies scotch tape:
http://multimedia.mmm.com/mws/mediaw...4spSxgrOkF W-