As we all know, when the temperature rises to a certain area, the basic material (polymer or glass) is changing from a glass state, a solid state, and a rigid state to a rubber state. Therefore, the temperature at this time is called the glass transition temperature (Tg). That is, Tg is the mechanical property that specifies the glass transition temperature, that is, the maximum temperature at which the glass remains rigid. In other words, ordinary PCB substrates will not only soften, deform, melt and other phenomena at high temperatures. And the mechanical and electrical performance will also drop sharply, which will affect the service life of the product.
Needless to say, the normal PCB FR4-Tg is 130-140 degrees, the medium Tg is greater than 150-160 degrees, and the high Tg is greater than 170 degrees. Compared with standard FR4, high FR4-Tg has better mechanical and chemical heat and moisture resistance. The higher the Tg value, the better the heat resistance of the material. Therefore, especially in the lead-free process, the Tg is getting higher and higher.
High Tg PCB performance
With the rapid development of the electronics industry, high Tg materials are widely used in computers, communications equipment, precision instruments and instrumentation. In order to achieve high functionality and high multilayer development, PCB substrate materials require higher heat resistance as a prerequisite. Moreover, due to the emergence and development of high-density mounting technologies represented by SMT and CMT, in the case of thinning, small aperture, and fine wiring, the high heat resistance of the substrate and the substrate are increasingly inseparable.
Therefore, the difference between the general FR-4 and the high FR4-Tg is that mechanical strength, adhesion, water absorption, dimensional stability, thermal decomposition in the thermal state (especially after water absorption) in the thermal state are different conditions (such as thermal expansion ) The difference is obvious, high TgPCB is better than ordinary PCB substrate material. Therefore, in recent years, the demand for high Tg PCB is very large, but the price is higher than the ordinary PCB.
More importantly, high Tg materials are also very popular in the LED lighting industry. Because the LED cap dissipation rate is higher than ordinary electronic components, but the same structure of the FR-4 board is much cheaper than metal core PCBs such as aluminum core PCBs.
Advantages of high Tg PCB
- Higher stability: If you increase the Tg of the PCB substrate, it will automatically improve heat resistance, chemical resistance, moisture resistance, and device stability.
- Withstand high power density design: If the device has a high power density and a relatively high heat generation. Then high Tg PCB will be a good solution for thermal management.
- When reducing the heat generation of ordinary boards: a larger PCB can be used to change the design and power requirements of the device, and high Tg PCBs can also be used.
- Ideal for multi-layer and HDI PCB: As multi-layer and HDI PCB are more compact and have dense circuits, they will result in high levels of heat dissipation. Therefore, high Tg PCB is usually used in multilayer and HDI PCB to ensure the reliability of PCB manufacturing.
When is high Tg PCB required?
If your printed circuit board cannot withstand a thermal load not lower than Tg25 degrees Celsius, your application will require high Tg PCB. In addition, if your product operates in the temperature range of 130 degrees Celsius or higher, it can also ensure the safety of using 高Tg PCB. Needless to say, the main reason for high Tg PCB is the shift to RoHS PCB. As a result, more and more PCB industries are turning to high-Tg materials because lead-free solder to flow requires higher temperatures.
High Tg PCB applications
If the power density in electronic products is higher, and heat generation will interfere with the heat sink or other parts of the product, then high Tg PCB is the best solution. In addition, with the popularity of high Tg PCBs in recent years, you will find that Tg PCB is used in the electronics industry that can operate at higher temperatures. Therefore, we provide high heat resistance and high Tg PCBs to meet the needs of customers in different industries. These PCBs can meet customer specifications in a short delivery time. Therefore, they are some application examples as follows：gateway, radio frequency identification, inverter, antenna board, wireless booster, contract manufacturing services, low-cost PLC, embedded system development, embedded computer system, AC power supply.