As a novice in PCB industry, whether FR4 TG 130 is better or FR4 TG 180 is better, many people will be confused. Maybe you want the price of PCB to be FR4 TG 130, because the price of tg180 is higher than that of FR4 TG 130. However, from the perspective of professional suppliers, how to choose which is better? You need to know the following about TG.Generally speaking, the higher Tg, the more stable the material is in PCB and PCBA / SMT manufacturing process because the board is not affected by high temperature. The temperature of PCB hot lamination is about 180-200c, while in the reflux furnace of PCBA process, the temperature is 200-240c when the temperature is 10-30s. If you want to make multilayer (more than 10 layers) with blind hole and buried hole, which means you need multilayer hot lamination, it is recommended to use high Tg material.More importantly, if the working temperature of the assembled circuit board is about 130 ℃ or higher, a 180 TG high material must be used to prevent the circuit board from being replaced and ensure the reliability of the whole product.Similarly, the higher Tg, the more expensive the material.Which is better? The main factors to be considered here are the application and complexity of PCB. TG 130 can be used in normal PCB at room temperature below 100C, while high Tg materials are required for high temperature application products or multilayer PCB.Temperature changes can have a significant impact on PCB operation, reliability and quality. Temperature rise leads to material expansion, but the main materials used in PCB manufacturing have different thermal expansion coefficients. This can lead to mechanical stress, resulting in microcracks that may not be detected by electrical tests (open / short circuit tests) at the end of production. In the best case, these microcracks will lead to failure detection after brazing. In the worst case, it can cause random damage to the finished product!In 2002, ROHS directive was introduced to require the use of lead-free alloy in welding. The removal of lead will lead to an increase in the melting temperature, so the PCB will be exposed to a higher temperature during soldering (reflow soldering and wave soldering). According to the selected reflux process (single, two...) It is necessary to use PCB with proper mechanical properties, especially PCB with proper glass transition temperature (TG).
