# Diode survivability at 260°C

I have an idea for a project, which needs to be able to measure temperatures up to 260°C. The accuracy is not crucial (±5°C is fine) but it is important that it can measure lower temperatures too.

I initially thought of using a silicon diode such as the 1N4148 as forward voltage is proportional to temperature with a nice linear slope of -2.1mV/°C. The current will be <100µA.

However, it looks like these diodes cannot survive a temperature this high, although it is not specified exactly what failure might occur. Can I expect the silicon die to break down and not work properly at this temperature, even though the current is low? The environment will be 260°C for 3-10 minutes, so it looks like any soldering rating is irrelevant.

If this does not work, what other low cost options are there for measuring high temperatures?

• Have you googled "thermocouple" yet? – The Photon Jan 21 '12 at 1:24
• @The Photon I did consider thermocouple, but that would involve a thermocouple amplifier, which isn't necessarily cheap. Then again, it may be the only option. – Thomas O Jan 21 '12 at 9:52