Discussion to be added at some
time.
It is a
matter of great controversy, but I recommend using thin PC boards to bring out
the leads. You can make tiny strip
lines on a pc board and avoid electronic signal problems. I cannot emphasize this too much. I have seen some detectors that are
pretty awful from an electronic signal standpoint. Also, copper (the PC trace) has the best ratio of electrical
conductivity (good) to thermal conductivity (bad) for bringing out a lead of
any material that I have found.
The real reason people use constantan and the like over copper is that
an equivalent copper wire is fragile, and has high inductance. Epoxy has about 1/1000 the thermal
conductivity of copper, so the board can be designed so that the copper is the
dominant conductor.