A thermocouple attached to the bottom side of a component using aluminum tape secured with a window-pane of Kapton tape
Previously in this blog series, we discussed some of the best practices for attaching thermocouples to a printed circuit board (PCB) for reflow profiling. Today, I will end this series with a few more tips.
Tip #1: Recommended thermocouple attachment method:
- Soldering thermocouples to the solder joint with a high-melting temperature solder is the preferred method of attachment.
- If the thermocouples cannot be soldered, the next best method for attachment is to use thermally conductive epoxy or aluminum tape. However, be careful not to poke holes in the tape. For multiple reflow cycles, the tape and/or epoxy may need to be reapplied over time.
- Kapton tape is not recommended for attaching thermocouples because it is an insulator and generally does not produce accurate temperature readings. However, Kapton tape can be used to window pane around aluminum tape for extra security. Make sure the Kapton tape does not cover the tip of the thermocouple where the temperature reading occurs.
Tip #2: It is best that the thermocouple wires are similar in length so they do not get tangled when going into the reflow oven. Thermocouple wires can be fed through a sleeve to ensure they do not become entangled.
Tip #3: Make sure the profiler is at least a full board’s length away from the board so that the thermal mass of the profiler does not affect the temperature results.