In order to get an accurate reflow profile of a Printed Circuit Board (PCB), it is important to keep best practices for attaching thermocouples in mind.
The first thing to remember is that a thermocouple is made of two wires welded together at the tip. This welded tip is where the temperature measurement is taken. It is important to ensure wires are not twisted around each other because the reading will be at the first junction of the wires and not at the tip where expected.
It is also very important to know that using a populated PCB is the best way to measure the most accurate temperature readings of the assembly. When comparing the temperature measurements of a populated PCB versus a bare PCB, there can be temperature differences up to 10°C or more. That said, using a bare, unpopulated board for reflow profiling is not recommended.
Stay tuned for more reflow profiling best practice suggestions!