What's the perfect temperature for dismount a digitizer?

Antonio, this is highly dependent on what adhesive the manufacturer uses. The common range is between 60deg and 100deg Celsius. Do not go past 110 since that will definitely destroy the LCD. Yes, that thermometer will work but is not optimal for your work. I use a couple of inexpensive K-type thermocouple thermometers ( something like this . That way I can keep my hands free to work on the display. Even with all the right tools etc, it will still take practice. Hope this helps, good luck.