Tg stands for Glass transition temperature. Tg is the base material parameter that stands for the temperature (°C) on which the base material become mechanically unstable. Tg is the value that needs to guarantee the mechanical stability of the PCB during operational life time of the PCB.
Contents
1 What is Tg value?2 What is high Tg PCB
3 What is the rule of UL
What is Tg value?
The Glass Transition Temperature (Tg) is one of the most important properties of any epoxy and is the temperature region where the polymer transitions from a hard, glassy material to a soft, rubbery material.TG refers to the glass transition temperature, which is the glass transition temperature of the plate under high temperature heating. The higher the TG value, the better the temperature resistance of the plate.
What is high Tg PCB.
The normal Tg value of AiPCBA is the same as normal FR4 PCB as 130-140C, and customer can also ask for high TG (170-180C), AiPCBA will sourcing for you. When the temperature of high Tg PCB increases to a certain area, the substrate will change from "glass state" to "rubber state", and the temperature at this time is called the glass transition temperature (TG) of the board. In other words, TG is the maximum temperature (℃) at which the substrate remains rigid. In other words, common PCB substrate materials not only soften, deform and melt at high temperature, but also show a sharp decline in mechanical and electrical properties. Generally, TG is above 130 degrees, high Tg is generally greater than 170 degrees, and medium TG is about 150 degrees. Generally, the PCB with TG ≥ 170 ℃ is called high Tg PCB. High Tg refers to high heat resistance. With the rapid development of electronic industry, especially the electronic products represented by computers are developing towards high functionality and high multi-layer, which requires higher heat resistance of PCB substrate materials as an important guarantee. The emergence and development of high density mounting technology represented by SMT and CMT makes PCB more and more dependent on the support of high heat resistance of substrate in small aperture, fine circuit and thin shape.
What is the rule of UL
For FR-4 to maintain electrical properties, that might be 130°C (a bit higher for mechanical properties). If the maximum temperature in the vicinity of your PCB will not exceed 60°C you could conceivably allow for 70°C rise. For FR-2 it might be 105°C, so the limit might be 35°C rise. UL is the abbreviation of (underwriter Laboratories Inc.). UL safety testing institute is the most authoritative institution in the United States, and also a large private institution engaged in safety testing and identification in the world. The UL + number on the PCB mainly represents that the circuit board has been certified by UL in the United States. Generally, it is a flame retardant test. There are several levels of flame retardant test V0 V1 (105 degrees, 130 degrees, etc.) and so on. However, if no certificate is issued, it can only be queried on the UL website and confirmed according to the UL number of PCB