What is PCB Tg?

- Apr 11, 2016-

What is Tg? (Glass Transition Temperature)

Circuit board must be fire resistant, it couldn't burn at certain temperatures, it can only be soften. This temperature we called the glassy state transformation temperature (Tg), this value is related to the PCB board stability.

High Tg PCB

When the temperature rises to a certain area, the base board will change from "glassy state" to

"rubber state", the temperature at this point is called the plate glass transition temperature


It means, the Tg is to maintain the rigidity of base material the highest temperature (℃).

Standard PCB substrate material at high temperature, not only produce the phenomenon such as 

softening, deformation, melting, it is also reflected in the sharp decline in mechanical and electrical properties.

General PCB's Tg is higher than 130 ℃.

Medium PCB's Tg is higher than 150 ℃.

High Tg PCB is generally higher than 170 ℃.

Substrate of Tg raised, PCB heat resistance, moisture resistance, chemical resistance, resistance to stability characteristics will improve and improve.

The higher TG, the better for performance of resistance to temperature,

Especially in the lead-free process, high Tg application more.

Standard FR-4 material with high Tg FR-4 difference:

Under the hot, especially under the moisture absorption after heated, the mechanical strength of the materials, size stability, adhesion, water absorption, thermal decomposition, thermal expansion and other differences, high Tg products is significantly better than the ordinary PCB substrate materials.

High TG material is more expensive than standard FR-4, so you can choose material as your PCB's working temperature and working environment.

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