Great piece of temperature measurement by Patrick.
The grp can consider two ways to measure the temp with cover on:
1. Use a good thermister- EPCOS B57862S282A9 Miniature Bead Thermistor. Not so accurate but god enough since you can compare with surrounding Ics. Accuracy up to? 1 to 2degree C is achievable. ?US 50cents per piece, ?Ebay.?
2. Use the LM35DZ, To92. Pretty accurate. Us $1 per piece. Ebay. ?
Both can be sticked to the Ic/heatsink? and the wires can be outside the scope. ?
cslim