The thermistor ATH10K1R25, ATH10K1R25T70 or  ATH10K1R25T70S can be used to sense solid block  temperature with high stability and accuracy. The best way to  mount the thermistor is to drill a hole on the object for which  the temperature needs to be measured and regulated, and use  thermal conductive epoxy to pot the thermistor inside the  hole. The diameter of the hole should be 1.4 to 1.8mm and  the depth should 3 to 4mm. When a deeper hole is needed,  drill a 2 stage hole to prevent epoxy bubbles trapped inside  the deep hole which could cause temperature measurement  errors. Figure 5 shows the section view of the 2 stage hole.