DIYbanter - View Single Post

amdx[_3_]

On 2/27/2018 7:01 PM, wrote:
On Tuesday, February 27, 2018 at 10:38:26 AM UTC-5, Ed Huntress wrote:
Another off-the-wall tip from my old manufacturing editor's resources:

Electrically-conductive epoxies are showing up in a lot of industrial
applications, replacing solder. They may solve some problems for
hobbyists, too.

Here is another off the wall tip. When you clean the surface before using the epoxy' do not use a citrus based cleaner. I can not remember it Very well, but we used silver filled epoxy to glue a ground to the rocket motor. Very thing worked well when we used 1-1-1 Trich. But in a change to a citrus based solvent we ran into problems in just that one case. Every seemed good but about 24 hours the ground would become unattached. The factory people that had selected the citrus based solvent essentially said use the damn citrus solvent. It is a universal solvent. And really put the pressure on. But one of the gov engineers and I ran some tests and the damn grounds would just fall off after a long time.

My manager said to stop doing tests and that he could have me fired for running tests like that. And I said go ahead and fire me. My manager and I really got along well so he softened that to " well tell me what the test results are." Eventually the factory engineers gave up and we did not use the citrus based solvent in that one case. I do not know if it was just that the silver filled epoxy had less strength or if the silver and citrus based solvents were not compatible.

Dan

I worked at a small company that built ultrasonic transducers.
The transducers were a 2" ceramic piezo bonded with epoxy to
a 1/16th inch aluminum disc.
After lapping the two surfaces together using a figure 8 lapping
motion the pieces were rinsed in water, lapped some more, rinsed
in acetone, this was repeated a couple times and then the pieces
were left in the acetone tray to prevent any oxidation of the
aluminum, as prep was made to install the epoxy.
We drove these at 660kHz with 1000 watt or pulses 250 watts
continuous. We drove never had a bond separation, but we
did burn up a few.
Mikek