As the electronics industry is developing, especially electronic products such as computers, because it has high functionality and high-density circuit characteristics, PCB substrate materials need higher heat resistance. in addition, The high-density mounting technologies such as SMT and CMT also needs the support of higher heat resistance of substrates, thus, High Tg PCB is prior to these projects.

The basic definition of the high-Tg circuit board

When the temperature of a high Tg printed circuit board rises to a certain threshold, the substrate will change from “glass state” to “rubber state”. The temperature at this time is called the glass transition of the board Temperature (Tg). That is, Tg is the maximum temperature (°C) at which the base material remains rigid. In other words, ordinary PCB substrate materials continue to soften, deform, melt, etc. at high temperatures, but also show a sharp decline in mechanical and electrical characteristics, which affects the service life of the product (I think everyone does not want to see themselves Products).

Main characteristics of the high-Tg PCB

Generally, the general laminate is around 130°C, the high Tg is greater than 170°C, and the medium Tg is approximately greater than 150°C.

PCB circuit boards with Tg≥170℃ are called high Tg printed boards. when the Tg temperature of the substrate is increased, the characteristics of heat resistance, moisture resistance, chemical resistance, and stability of the printed board will be improved.

The higher the TG value, the better the temperature resistance of the substrate. Especially in the lead-free process, high Tg is more widely used.

Therefore, the difference between general FR-4 and high Tg FR4, is that High Tg products are obviously better than ordinary PCB substrate materials in respect of the mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion, etc.

High Tg materials are regularly stored per month, like Tg140 FR-4, Tg150 FR-4, and Tg170 FR-4, however, TG180 laminate needs to be ordered in advance.