What is PCB Tg?

(Glass transition temperature): The temperature at which the material stops acting like a rigid material and begins to behave like a plastic / softer.

Requirements are primarily driven by peak temperature, which is driven by component and board size / thickness / complexity. With small components and a small board, Tg between 130 and 150C can be sufficient. Larger components and a larger board tend to need Tg closer to 170C to 180C.

High TG circuit boards?

The glass transition temperature (Tg) is an important normative dimension for the base material that determines the temperature at which the resin matrix converts from a glassy, brittle condition into a soft, elastic one. The Tg value of the base material sets here an upper boundary, at which the resin matrix decomposes and a subsequent delamination occurs. The Tg is thus not the value of the maximum operational temperature, but rather that which the material can endure for only a very short time. A guideline for a continuous thermal load is an operating temperature approximately 25°C below the Tg.When the glass transition temperature (Tg) is over 170°C, it is referred to as a high Tg material.

Please visit High Tg PCB for more information if need,meanwhile you will get the information for TG170.