[sdiy] temperature testing

[rsdio at audiobanshee.com]

On May 11, 2017, at 11:05 AM, matt holland <matt at mattholland.org> wrote:
> Multiple thermocouples... to be certain you aren't being misled by hotspots on the PCB?

The key is that if any part your circuit does overheat, then you'll need to fix the design. You need multiple thermocouples in order to find out which chip is the one that's overheating, and that in turn will tell you which part of the circuit needs adjustment. There's also the fact that different chips are rated for different maximum temperatures, so you'll need to know the precise temperature of each chip to know whether your product has "failed." You can't wait for total failure of the product itself, because not every chip is going to instantly stop working just because you've gone above its temperature limit. However, you want to make sure that your circuit design prevents each individual chip from exceeding its ratings, otherwise you have no guarantee that your product will last.

I've seen the process and the mess of thermocouples on prototypes, but I've never actually run these tests myself. I'm guessing that if the ambient temperature exceeds the chip ratings, then there's no circuit that could pass the test without refrigeration. Standard fans can only help when ambient air is cooler than the parts need to be. I've seen the reports, and they mention which chip exceeded its temperature limits, and under what conditions. This usually allows the circuit designer enough clues to reduce the heat in the problem areas.

Brian