SMA diode carrying 1.08A is 127degC in 20degC ambient

[treez]

Hi,
Today I recorded a temperature of 127 degC (with a Flir E8 thermal cam) on a BYG10M SMA diode which was carrying 1.08A of DC current. This was on a PCB in open air lab ambient with no fan blowing.
Lab was 20 degC. The BYG10M footprint was minimum (no added extra thermal copper pour).
The emissivity was set to 0.9

Do you think there could be some mistake here with this temperature recording?

BYG10M diode

http://www.farnell.com/datasheets/1838676.pdf

Flir E8

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[FvM]

The measured temperature fits well the specified Rth values and expectable power dissipation.

 

[dick_freebird]

Do you think there could be some mistake here with this temperature recording?

It would be a good idea to take a resting temperature
measurement before applying stress, with a reference
reading from some instrument you trust.

It is simple to attach a thermocouple to a sample
device's backside and power it similarly, and aim the
IR gun at the frontside, looking for agreement at a
second temperature.

"Two rights make it not far wrong"....

 

[Easy peasy]

1W or just over on an SMA with min foot print - it will get hot - read the data sheet and do the maths ...

 

[treez]

Thanks, datasheet says 150degC/W when mounted on "epoxy glass , hard tissue".
We are not sure what that means, but guess it means min footprint?...so we would expect junction temp of 150degC plus ambient = 170degC.