Sometimes, the world synchronizes

A while ago I bought a reflow oven to assist in the assembly of prototype PCBs that I design for my clients. Prior to running the first boards through the oven I used my digital multimeter and a thermocouple to check and optimize the reflow temperature curve for the solder paste I had chosen. The process went well and it has produced a number of prototype PCBs. Along the way the oven has needed a few tweaks to accommodate PCBs with large ground planes. The thermocouple used for reflow curve measurement however has not fared well, the insulation of the thermocouple wire melted!

Melted thermocouple wire

Recently my wife began a new job at Kairos Power in Albuquerque as a Wiring Harness Technologist. She told be about the hundreds of thermocouples she was going to be wiring as a part of the project she was working on. She described the wire they were using and I began to wonder if I could track down a better thermocouple with a more heat resistant wiring. A little Internet searching revealed a suitable thermocouple from Adafruit.

Adafruit Thermocouple Type-K Glass Braid Insulated

The new thermocouple was very nicely made with the thermocouple inside what looks like a stainless steel shell. It did not have a K-Type connector on it so I recruited my wife to remove the connector from the original thermocouple and use it on the new one. The original wire fit through the strain relief of the K-Type connector, however the new cabler was a little larger. Trusty lacing twine was used to secure it.

K-Type connector with braided wire and strain relief

The thermocouple is taped to a PCB using Kapton tape so that it may be placed into the oven in a similar position as the PCBs to be reflowed.

Serendipity inspired the search for the new thermocouple and gave me access to someone with the skill to do a really nice job of attaching the connector!