Rigid PCB Copper Clad Laminate

Copper Clad Laminate, also known as PCB laminate, is an indispensable substrate material in the manufacturing of printed circuit boards. Its core feature is a thin layer of copper that is laminated on one or both sides of the board, giving rise to the common terms “single-sided CCL” and “double-sided CCL.”

During the production of rigid circuit boards, manufacturers rely heavily on specially designed rigid CCLs that are typically composed of substrate materials, such as resin epoxy (FR4), metal core (aluminum or copper), PTFE, and ceramic. These materials are used to fabricate various types of circuit boards, including single-, double-, and multi-layer circuits.

Thanks to its unique composition, CCLs play a crucial role in ensuring the rigidity, stability, and durability of PCBs, even in harsh operating environments. Manufacturers must therefore understand the characteristics and properties of each type of CCL material and select the most suitable one for their specific application.

Resin Epoxy FR-4 Copper Clad Laminate

FR-4 Copper Clad Laminate refers to a specific type of rigid PCB substrate material that has copper cladding on one or both sides of the base, which is made of a composite material comprised of woven fiberglass cloth bonded with an epoxy resin binder. The material is known for its flame-resistant properties, denoted by the “FR” abbreviation, yet it is important to note that compliance with the standard UL 94V-0 is not automatic and must be tested at a compliant lab according to Section 8 of UL 94 Vertical Flame testing. The term “FR-4” was coined by the National Electrical Manufacturers Association (NEMA) in 1968.

Due to its excellent electrical insulation properties and rigid structure, FR-4 CCL is widely used in the PCB industry for manufacturing printed circuit boards. The woven fiberglass cloth provides the necessary strength and stability, while the epoxy resin binder creates a strong bonding agent that secures the copper cladding to the base material. In addition to being an excellent electrical insulator, FR-4 CCL also offers good thermal conductivity properties, making it a popular choice for high-power applications.

FR-4 CCL is available in various thicknesses, copper weights, and sizes, and it can be classified into two main types: single-sided and double-sided. Single-sided FR-4 CCL has copper cladding on one side, while the other side remains unclad. Double-sided FR-4 CCL has copper cladding on both sides, with holes drilled through the substrate to allow the conductive paths to be routed between the two layers.

In summary, FR-4 CCL is a composite material that provides excellent electrical insulation and thermal conductivity properties, making it a popular choice for manufacturing printed circuit boards. Its flame-resistant properties, denoted by the “FR” abbreviation, make it a safer option for electronic devices that require high durability and reliability.

FR-4 Copper Clad Laminate Properties

1. Low glass transition temperature (Tg): Tg130°C – Tg140°C

2. Mid glass transition temperature (Tg): Tg150°C

3. High glass transition temperature (Tg): Tg170°C

4. High decomposition temperature (Td): Td>345°C

5. Dielectric constant (Dk or Er) at 1 GHz: 3.66-4.5

6. Dissipation factor (Df) at 1 GHz: 0.016

7. High UL rated flammability: 94V-0

8. Low coefficient of thermal expansion (CTE): 2.5%-3.8%

9. High comparative tracking index (CTI): CTI >=600V

10. Halogen-free

11. Compatible with standard and lead-free assembly

12. Available FR4 CCL thicknesses: 0.2mm to 3.2mm

13. Available copper foil weights: 1/3oz to 3oz