I noticed that no one has posted measurements on the thermal pads used on the Framework 13, so I made my own measurements while I had the heatsink removed. Normally, the thermal pads does not need to be replaced whenever the heatsink is removed from the mainboard. However, you may choose to replace them as the computer ages, or as part of performance modding the mainboard. Note that this is the thermal pads used for the VRM MOSFETs and coils, not for the CPU / SOC itself. This is measured on the 12th gen Intel mainboard.
Main CPU power rails MOSFETs (yellow): 27mm x 5.5mm x 2.3mm*
Main CPU power rails coils (red): 27mm x 6.5mm x 0.5mm
GPU MOSFETS (blue): 5mm x 5.5mm x 2.3mm*
GPU coils (green): 5.3mm x 5.5mm x 0.5mm
*I measured the pads to be 2.3mm thick, although the imprints on it suggest that it might be a 2.5mm pad that flattened out when installed. 2.5mm is an uncommon size, which may require stacking 0.5mm and 2.0mm pads together. Further testing is needed if 2.0mm would work. Too thin may cause poor thermal contact. Too thick can lift the heatsink, causing poor thermal contact on other components such as the CPU.
Bigger than measured pads will work fine, as long as it’s non-conductive, and it doesn’t interfere with heatsink fitment.
I also measured the 12th gen Intel CPU / SOC die for liquid metal or graphene pads. The advertised CPU die is 24mm x 12mm. However, the actual size is 28mm x 12mm when including the SOC die.