What We Talk About When We Talk About Tg.
What is Tg?
Tg is short for "Glass Transition Temperature". It indicates the critical temperature between the state of Glass and Rubbery(It is different from the working temperature of the material. ).When exposed in moisture and especially after heated, the mechanical strength、dimensional stability would be severely affected. And all of these would lead to a possible functional failure.
Is Tg useful?
Yeep.When you choose the FR-4 Substrate Material which would be used for your Printed Circuit Board.
Normally there are 3 kinds:
Normally Tg (130℃-150℃ 266 F-302 F）
Midium Tg (150℃-170℃ 302 F-338 F）
High Tg (170℃ or above 338 F or above)
It is different from the working temperature of the material.
How to choose the material ?
Higher level Tg Material would be a good choice when you expect a good proformance for the mechanical strength、dimensional stability and especially if the working environment is harsh.