What is "Tg" and Why it Matters Tg stands for "glass transition temperature." In the context of PCBs, it refers to the temperature at which the PCB material undergoes a transition from a solid state to a more viscous, glass-like state. The Tg of a PCB material is an important factor to consider when designing a PCB, as it can affect the PCB's performance in various ways. For example, if the Tg of the PCB material is too low, the PCB may become too flexible when exposed to high temperatures, which could cause it to deform or break. On the other hand, if the Tg of the PCB material is too high, the PCB may become too rigid and brittle, which could also lead to problems. In general, PCB materials with a high Tg are preferred for use in high-temperature environments, as they are less likely to suffer from thermal expansion and other problems that can occur at high temperatures. However, it is also important to consider other factors such as the cost and availability ...