{"id":1207,"date":"2023-01-04T09:58:19","date_gmt":"2023-01-04T01:58:19","guid":{"rendered":"http:\/\/www.bestpcbs.com\/blog\/?p=1207"},"modified":"2023-01-04T09:58:21","modified_gmt":"2023-01-04T01:58:21","slug":"everything-you-should-know-about-tg-in-pcb","status":"publish","type":"post","link":"https:\/\/www.bestpcbs.com\/blog\/2023\/01\/everything-you-should-know-about-tg-in-pcb\/","title":{"rendered":"Everything you should know about Tg in PCB"},"content":{"rendered":"
<\/div>\n

Working temperature changes can have a significant influence on the operation, reliability, lifetime and quality of products. Temperature rises results in materials expanding, however,\u00a0the substrate materials that PCB<\/a> are made of\u00a0have different thermal expansion coefficients, this causes\u00a0mechanical stress that can create micro-cracks\u00a0that may be undetected during electrical tests carried out at the end of production.<\/p>\n\n\n\n

Due to the policy of RoHS issued in 2002 required\u00a0lead-free alloys for soldering. However, removing lead directly results in the rise of melting temperature,\u00a0printed circuit boards are therefore subject to higher temperatures\u00a0during soldering (including reflow and wave). Depending on the chosen reflow process (single, double\u2026), it is necessary to\u00a0use a PCB with appropriate mechanical characteristics<\/strong>, especially one with suitable\u00a0Tg.<\/strong>\u00a0<\/p>\n\n\n\n

What is Tg?<\/h2>\n\n\n\n

Tg<\/strong> (glass transition temperature) is the temperature value that guarantees the mechanical stability of the PCB during operational life time of the PCB, it refers to the critical temperature at which the substrate melts from solid to rubberized liquid, we called the Tg point, or melting point for easy to understanding. The higher the Tg point is, the higher the temperature requirement of the board will be when laminated, and high Tg board after laminated will also be hard and brittle, which benefits for next process such as mechanical drilling (if any) and keep better electrical properties during use.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

The glass transition temperature is hard to be measured accurately in considerate many of factors, as well as each material have its own molecular structure, therefore, different materials have a different glass transition temperature, and two different materials may have the same Tg value even they have different characteristics, this enable us to have an alternative choice when the needed material is out of stock.<\/p>\n\n\n\n

Features of High Tg materials<\/strong><\/strong><\/p>\n\n\n\n