Electronic – Connectors for horizontal and vertical mount

The most important part of how/where/when for connecting a thermocouple is to measure the temperature as close as possible to the bimetalic joint.

From here feed that temperature into your uP and then you can use software to perform the CJC compensation and use the known polynomials (or simplified linearised equation for smaller ranges) for converting your ADC value into temperature.

In the past we have got a big chunk of aluminium and performed wire to wire terminations around it and installed a LM35 for temperature measurement. This was performed off the PCB.

Having said that you can freely do it with connections n stuff on the PCB as long as for are able to measure the temperature as close as possible to the bimetalic junction.

So to keep the distance as short as possible consider using screw terminals and mount the LM35 right near the screw terminals themselves for the most accurate reading. If you really want to use a connector try DB9 with the metal back shell - cheap as chips and being metal will conduct heat well for accurate measurement of the back shell temperature. Use male pins on the PCB.

I assumed you are using a uP and software, if not you can do the CJC in hardware but thats a bit trickier.

Hope this helps.

They are almost certainly not in any danger. Not any more than the fact that they handled the board and possibly ate something before washing their hands. Direct transfer probabilities are much higher than a double outgassing transfer, first to oven and from oven to food. In the oven of course you have the potential for outgassing, which then coats out on the inside of the oven. I doubt that there is a lot of this. On top of it, people typically preheat the oven which would spike the temperature up again beyond this "reflow" temp and this would liberate the bad stuff (if it was there) and carry it out of the oven. i.e. it would be baked out.

Boards are relatively clean, lead is not very volatile, there are VOC present but once heated they dissipate etc. you wouldn't want to use an oven that is exclusively used for this, but once in a while is most likely very very safe.

In fact the oven elements when new outgas on first use, after cleaning the oven there are chemicals left on surfaces that outgas. Those would be the best comparables and more concerning than the PCB.