Everything You Should Know About the Tg of PCB

Views: 55     Author: Site Editor     Publish Time: 2020-06-01      Origin: Site

What is FR-4?

FR-4 is a grade of flame-resistant fibreglass reinforced epoxy material. Therefore, FR-4 PCB has higher heat resistance than standard PCB. The FR-4 boards are divided into three categories, determined by the number of copper traced layers:

1. Single-layer printed circuit board

2. Double-layer printed circuit board

3. Multi-layer printed circuit boards


What is Tg?

The Glass Transition Temperature "Tg" refers to the glass transition temperature of a PCB. It indicates the point at which the material of the printed circuit board will start to change.

If the operating temperature exceeds the specified Tg value, the printed circuit board will start to change from from glassy state to rubbery state, which may adversely affect its function (as shown in illustration).


That is to say, Tg is a mechanical property that designates glass transition temperature, that is, the highest temperature at which the substrate remains rigid.

It goes without saying that standard PCB is made of materials with TG values of 130~140 centigrade. Medium PCB with Tg value of 150~160 centigrade. High PCB with TG value of 170~180 centigrade. In the hot state, high Tg FR4 will have better mechanical and chemical resistance to heat and moisture than standard FR4.

Therefore, the higher of Tg, the better the performance of PCB heat resistance, moisture resistance, chemical resistance, stability and other characteristics.

Below the Tg of different PCB base materials:

Base material






FR4 High Tg












Typical application areas

PCB with a high Tg is the best solution if there is a high power density in electronic products and heat generation interferes with the heat sink or other parts of the product. Additionally, with the wide application of high Tg PCB in recent years, the application of Tg PCB in electronic industry is more and more extensive. Therefore, we offer high Tg PCBs heat resistance to customers in different industries, meet customer specifications and meet fast delivery dates. Here are some examples of applications:

1. Multi-layer board

2. Industrial Electronics

3. Automotive Electronics

4. High temperature electronic element

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