The higher the Tg point, the higher the temperature requirement for pressing the plate, and the pressed plate will also become hard and brittle, which will to some extent affect the quality of mechanical drilling in the subsequent process.
The general Tg film is above 130 degrees, High Tg is usually above 170 degrees, and the medium Tg is above 150 degrees. The Tg of the substrate has been improved, including heat resistance, moisture resistance, chemical resistance, stability, etc., and the functionality of the printed circuit board will continue to improve.
The higher the TG value, the better the heat resistance of the board, especially in lead-free tin spraying process, where high Tg application is more common,
With the rapid development of the electronic industry, especially in electronic products represented by computers, towards high functionality and multi-layer development, higher heat resistance of PCB substrate materials is needed as an important guarantee. The emergence and development of high-density installation technologies represented by SMT and CMT have made PCBs increasingly dependent on the support of high substrate heat resistance in terms of small aperture, fine wiring, and thinness.
So the difference between general FR-4 and high Tg FR-4 is that in the hot state, especially when heated after moisture absorption, there are differences in the mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion and other aspects of the material. High Tg products are significantly better than ordinary PCB substrate materials. In recent years, the number of customers who require the production of high Tg circuit boards has been increasing year by year.
