What is a high Tg PCB material?
The full name of TG used in PCB production is glasstransition temperature, which stands for glass transition temperature. The circuit board must be flame-resistant, cannot burn at a certain temperature, but can only be softened. The temperature point at this time is called the glass transition temperature (Tg point), and this value is related to the dimensional stability of the PCB board. The higher the TG value, the better the temperature resistance of the PCB. When the temperature rises to a certain area of high Tg PCB, the substrate will change from "glassy" to "rubbery". This temperature is called the vitrification of the sheet (Tg) Transition temperature. In other words, Tg is the maximum temperature (°C) that the substrate temperature maintains. That is to say, ordinary PCB substrate materials not only produce phenomena such as expansion, deformation, melting, but also a sharp decline in mechanical properties and electrical characteristics at high temperatures.
The increase of the Tg of the substrate, the characteristics of the heat resistance, moisture resistance, chemical resistance, and resistance stability of the circuit board will be strengthened and improved. The higher the TG value, the better the temperature and other performance of the board, especially in the lead-free manufacturing process, there are more applications of high Tg.
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 technologies represented by SMT and CMT have made PCBs more and more inseparable from the support of high heat resistance of substrates in terms of small aperture, fine wiring, and thinning. This is also a big reason why high TG materials are used in PCB production.
Therefore, in PCB production, the difference between general FR-4 and high Tg FR-4 is the mechanical strength, dimensional stability, adhesiveness, and water absorption of the material in the hot state, especially when heated after moisture absorption. There are differences in performance, thermal decomposition, thermal expansion and other conditions. High Tg products are obviously better than ordinary PCB substrate materials.
