1. What is Tg?
Tg, or glass transition temperature, refers to the critical temperature at which PCB materials transition from a hard, brittle “glass state” to a soft, plastic “rubbery state” under heat. It can be simply understood as the melting point where the substrate begins to soften and lose rigidity. It is important to note that Tg is not an absolute fixed value; its measurement results can be influenced by the testing method and conditions. Currently, the industry commonly uses the IPC-TM-650 standard for Tg testing to ensure comparability and reliability of results.2. Classification of Tg Values: Low, Medium, HighBased on different Tg values, materials are generally classified into three categories:
- •Standard Tg (Low Tg): Tg ≥ 130℃
- •Medium Tg: Tg ≥ 150℃
- •High Tg: Tg ≥ 170℃
3. Why is Tg Value So Important?
1. Impact on PCB Processing Technology
Materials with higher Tg values require higher temperatures during lamination. Additionally, high Tg materials result in a harder and more brittle board after lamination, which directly affects the quality of subsequent mechanical drilling and other processing steps—if not controlled properly during drilling, issues such as delamination and burrs can easily occur.
2. Determines the Reliability of the Final Product
The Tg point is the upper temperature limit at which the substrate maintains mechanical strength and stable electrical performance. Once the operating temperature exceeds the Tg value, the material will soften and deform, leading to a sharp decline in its mechanical and electrical properties.Therefore, high Tg materials have the following advantages:
4. How to Choose the Right Tg Material?
When selecting PCB materials, it is essential to comprehensively consider the final operating environment and performance requirements of the product: Mainstream material suppliers also offer a rich product line for engineers to choose from, such as:Nanya Materials:
- • Better heat resistance, suitable for high-temperature soldering or high-temperature working environments;
- •Higher moisture and chemical resistance;
- •More stable long-term reliability, suitable for high-demand fields such as power devices, automotive electronics, and communication equipment.
- •Standard Tg: NY2140
- •Medium Tg: NY2150
- •High Tg: NY2170
- Shengyi Materials
- • Standard Tg: S1141
- •Medium Tg: S1000-H
- •High Tg: S1000-2
- •Standard consumer electronics (such as mobile phones, Bluetooth headsets) can use standard Tg materials (such as 130℃–140℃) to meet requirements;
- •For industrial control, automotive electronics, network devices, etc., it is recommended to choose at least medium Tg or high Tg materials to ensure long-term stability in complex environments.