First is to look at the science and technology, passive components thermistor applications, whether using harsh environmental temperature or general environment, are very emphasis on the selection of B value, usually take 25 ° C - 50 ° C and some high temperature such as microwave ovens, must ask B value in the range of 25-200 degrees, 100 degrees to 100 degrees that I have ever seen the B value, in this manufacturing thermistor its difficult.General domestic factory B value is 25 ° C - 50 ° C, we are all 25 ° C to 85 ° C and 300 ° C.The difference in the manufacturing process and technology.