We all know importance of clean copper-copper connection to reduce TEMFs and contact resistance, especially doing sensitive low-voltage measurements, but how you guys keep contacts clean?
I saw different methods, but rarely see anyone shared techniques they used to keep connector clean.
My main question is regarding copper non-plated terminals, as they oxidize really quick.
It's much less of a problem with gold-plated terminals, but still could be an issue there.
Here's some real data how badly this can screw measurements:
![](https://xdevs.com/doc/xDevs.com/caveat_res.png)
Setup : 3458A sampling on VHP101 95K 0.005% resistor with PMO, specified at 0.3ppm/K in window +20 to +40C.
Brown bold line on graph is temperature from BME280 sensor, blue stagged line is TEMP?
Green bold line - ppm deviation (scale on most left) from median
Green dots - samples.
As you can see resistance go crazy with span almost 50 ppms! So before I doubt my 3458A proper operation, let's hook same resistor, using same connection wires to gold-plated bananas on K2002:
![](https://xdevs.com/doc/xDevs.com/caveat_res2.png)
Much less deviation, even though reading noise is way larger on Keithley 2002 (you can see sample dots all over the place). But what is more important - averaged resistance reading closely matches temperature graph, as it should be. In both cases connection done is using copper wire in 4-wire mode at DMM end and TRX connectors on
resistor box end.
I cleaned connection wire and reconnected it back to 3458 posts to get 2nd set of data. Will see how it goes tomorrow.
So I'd like to hear more about ways to keep sensitive gear terminals in good order, if you have something to share. Non-destructive methods are welcome.
![Popcorn :popcorn:](https://www.eevblog.com/forum/Smileys/default/EatingPopcorn.jpg)