In the past, cadmium solder was used because it had a low thermal property. Unfortunately, cadmium solder has been determined to be toxic and its use has been eliminated. Silver type solder is about the only solder that is commercially available today and safe to use, but it does not provide low thermal properties. Keithley's handbook, Low Level Measurements (available on request), offers very good suggestions on how to reduce thermal offsets. One such technique is to use a current reversing technique or an offset compensation method to eliminate thermal offsets. Keithley's 2010 DMM, 2400 SourceMeter instrument, and 2182 Nanovoltmeter can be used in a variety of methods to reduce thermal offsets. Check our list of White Papers for details on how to measure with nano-ohm resolution using the Model 2182/2400 combination.