Question 1

Q1: What does Tg value mean in PCB substrate?

Accepted Answer

A: Tg refers to glass transition temperature. It is the critical temperature where PCB base material changes from hard rigid state to soft rubbery state, directly deciding the thermal stability of circuit boards.

Question 2

Q2: What is the ideal Tg value for lead‑free soldering PCBs?

Accepted Answer

A: For standard lead‑free assembly process, PCB substrate Tg value should reach at least 170°C or higher to avoid board warpage and delamination under high reflow temperature.

Question 3

Q3: Which Tg grade is suitable for automotive PCB designs?

Accepted Answer

A: Automotive electronic PCBs are recommended to adopt high Tg material ranging from 170°C to 180°C, which can adapt to complex vehicle temperature changes and long-term working reliability requirements.

Question 4

Q4: How to select proper PCB Tg value according to working environment?

Accepted Answer

A: Calculate the maximum working temperature of the product, then reserve 20~25°C temperature safety margin, and select the corresponding level of Tg substrate higher than this standard temperature.

Question 5

Q5: Does higher Tg PCB material have more advantages?

Accepted Answer

A: Higher Tg brings better high temperature resistance and dimensional stability, but it will raise raw material cost and slightly increase board brittleness. It is best to choose matching Tg instead of blindly pursuing ultra-high Tg.

Question 6

Q6: Why high Tg substrate is necessary for multilayer and HDI PCB?

Accepted Answer

A: Multilayer and HDI boards go through multiple pressing and high-temperature processes. High Tg material effectively reduces Z-axis thermal expansion, greatly lowering the failure risk of inner layers and through holes.

Question 7

Q7: What applications use ultra-high Tg PCB substrates?

Accepted Answer

A: Ultra-high Tg materials above 190°C are mainly used in aerospace, military equipment, high-frequency communication and other extreme high-temperature and high-reliability electronic fields.

Thermal Performance

What Is the Tg Value of PCB Substrate? A Complete Guide for 2025 Designs