Monday, January 28, 2013

More 0402 Thermistors

In preparation of loading and testing the next revision of my PA47 Amp, I have started the process of joining FET and Thermistors, by mixing the glue - JB-Weld epoxy (see: previous posts).

For this build, I am using only JB-Weld, for the initial tack and then for the final cover. The JB-Weld web site provided some interesting data regarding strength and temperature resistant abilities. It suggests that JB-Weld is the right "glue" for this Thermistor attachment process.

It appears that a little too much of JB-Weld was mixed, but is actually is just a small drop, most of it will not be used.
Microscope at 7X

Here are some FETs with Thermistors attached with small mounts of JB-Weld. Soldered wires will be added after the epoxy has set.

2N7000 with Thermistors Attached

While under the Microscope I noticed that JB-Weld is not what it appear to the un-aided eye, it is actually gray with black flecks.
This the same as the First Image, only the
Microscope Set at 15X
After curing, this glob of epoxy was subjected to a test with a hot soldering tip, confirmed that JB-Weld is much more heat tolerant than Hobby Fast Cure Epoxy.


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