When the temperature of a high Tg printed board rises to a certain area, the substrate will change from “glass state” to “rubber state”, and the temperature at this time is called the glass transition temperature (Tg) of the board.

In other words, Tg is the highest temperature (°C) at which the substrate maintains rigidity. That is to say, ordinary PCB substrate materials not only produce softening, deformation, melting and other phenomena at high temperatures, but also show a sharp decline in mechanical and electrical characteristics (I think you don’t want to see this in your products).

Generally, Tg plates are above 130 degrees, high Tg is generally greater than 170 degrees, and medium Tg is about 150 degrees. Usually the PCB printed board with Tg≥:170℃ is called high Tg printed board. The Tg of the substrate is increased, and the heat resistance, moisture resistance, chemical resistance, stability and other characteristics of the printed board will be improved and improve. The higher the TG value, the better the temperature resistance of the board, especially in the lead-free process, where high Tg applications are more common. High Tg refers to high heat resistance.

With the rapid development of the electronics industry, especially the electronic products represented by computers, the development of high functionality and high multilayers requires higher heat resistance of PCB substrate materials as an important guarantee.

The emergence and development of high-density mounting technology represented by SMT.CMT has made PCBs more and more inseparable from the support of high heat resistance of substrates in terms of small aperture, fine circuit and thinning. Therefore, the difference between the general FR-4 and the high Tg FR-4: it is the mechanical strength, dimensional stability, adhesiveness, water absorption, and thermal decomposition of the material under the hot state, especially when heated after moisture absorption. There are differences in various conditions such as thermal expansion, high Tg products are obviously better than ordinary PCB substrate materials. In recent years, the number of customers requiring high Tg printed boards has increased year by year.