What is the high Tg FR4 and the advantages of high Tg PCB

Tg is the glass transition temperature, that is, the melting point.PCB must be flame resistant, can not be burned at a certain temperature, only soften, then the temperature point is called the glass transition temperature (Tg temperature).

What is the high Tg FR4? And what is the advantages of using high Tg PCB?

When the temperature rises to a certain threshold, the substrate changes from "glassy" to "rubbery",the temperature is called the glass transition temperature (Tg). That is to say, Tg is the highest temperature at which the substrate remains rigid. In other words, ordinary PCB substrate material at high temperatures, continue to produce softening, deformation, melting and other phenomena, but also in the mechanical, electrical characteristics of the sharp decline, this way will be affect the product life.The general Tg is ≥130℃,medium Tg is ≥150℃, high Tg is ≥170℃.Usually Tg ≥ 170 ℃ we call it high Tg PCB.Substrate Tg increased, the PCB heat resistance, Resistance to moisture, chemical resistance, stability and other characteristics will be improved.The higher the TG value, the better the temperature resistance of the material, especially in the lead-free process, high Tg applications are become more and more,high Tg refers to the high heat resistance. With the rapid development of the electronics industry, especially in the computer as the representative of the electronic products, toward to the high functionality, high multi-layer development, PCB substrate material needs higher heat resistance as a prerequisite. To SMT, CMT as the representative of the emergence and development of high-density installation technology, the PCB in the small drilling, fine circuit, thin, more and more inseparable from the material high heat resistance support.

Therefore, the difference between the general Tg FR-4 and the high Tg FR4 is that when they are at the same high temperature,especially after heat absorption,there are differences of the mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition and thermal expansion,high Tg PCB obviously better than general Tg PCB.