How to choose the PCB substrate material？

There are several types of PCB substrate materials available, each with its own properties and applications:

FR4: This popular material is a glass fabric laminate impregnated with flame-resistant epoxy resin. It is versatile, has good mechanical strength, and is widely used in various applications. However, it may not be suitable for high-speed digital circuits due to its high dielectric loss.

PTFE: PTFE is highly efficient and suitable for high-power and microwave PCBs. It offers excellent thermal conductivity, dielectric strength, and corrosion resistance. PTFE is often used in aerospace and defense industries.

Polyimide: Polyimide substrates have higher temperature performance and enhanced survivability in harsh environments. They are more expensive than FR4 but offer excellent flexibility, thermal stability, and chemical resistance. Polyimide is commonly used in flexible and rigid-flex PCBs.

CEM: CEM is a cost-effective alternative to FR-4. It comes in different types (CEM 1, CEM 2) and is made from woven glass epoxy, paper, and phenol compounds. CEM substrates have lower glass transition temperatures compared to FR4.

Alumina: Alumina is a ceramic-based substrate material suitable for high-frequency applications. It offers excellent thermal conductivity and is cost-effective. Alumina is commonly used in high-power boards that require efficient heat dissipation.

?

When selecting a PCB substrate material, consider the following factors:

1、Mechanical properties: Evaluate peel strength and flexural strength to ensure strong bonding and resistance to mechanical stress.

2、Electrical properties: Check dissipation factor, electrical strength, dielectric constant, surface resistivity, and volume resistivity for optimal signal integrity and impedance considerations.

3、Thermal properties: Consider coefficient of thermal expansion (CTE), glass transition temperature (Tg), and thermal conductivity to handle heat and prevent material expansion issues.

4、Chemical properties: Assess moisture absorption to ensure resistance against moisture and prevent undesired material property changes.