IPC 7530 section 7.3.1.1 Regarding K type thermocouples

Sr. Tech,

As far as I’m aware, most if not all, manufactures of thermal profilers offer K type thermocouples as a standard for profiling in the electronics manufacturing industry. In my decades of experience in the reflow and wave solder industry, temperature cycling hysteresis with K type thermocouples and how it may affect the accuracy of thermal profiles in excess of 250? C, has never been an issue. Maybe this is not a greater issue because, even with Lead-Free processes, temperatures are not often that far in excess of 250?C and not critical areas.

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I am not sure what the IPC spec is suggesting....K type thermocouples are normally specified upto 1250 C, of course there is a tolerance in their accuracy and this probably degrades after hundreds of uses through a reflow oven, but normally the accuracy won't stop you getting a profile within the limits of paste / pcb / components..I have only ever seen K type thermocouples used on reflow profilers..maybe if you are looking for a laboratory spec profile then there are better options but for a working production reflow profile K type is suitable.

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