I have a SOD-123F diode through which a current of ~1A flows, creating a forward voltage drop of around 300mV. The datasheet does not specify Rjc but gives Rja = 200 C/W and Rjl = 70 C/W for a 10cm x 10cm copper pad area (!). I only have 12 mil traces going to and from this diode, so I am far from this ideal heatsink scenario.
From thermal imaging data I have a top-side casing temperature of 65C (~40C elevation).
What can I do to evaluate the junction temperature ?
Since I do not have access to Rjc, I thought I could evaluate a worst case scenario with Rjc = Rja = 200 C/W (since in reality Rja > Rjc) and assuming ambient to be 65C instead of 25C:
Tj = Rja * P + 25C = 200C/W * 1A * 300mV + 65C = 125C
Which is just on the 125C limit allowed by the datasheet. There should be some margin in there since I used Rja > Rjc.
Any other thoughts ?