A Complete Guide to Copper Clad Laminate (CCL) in PCB Manufacturing

In the world of printed circuit board (PCB) manufacturing, Copper Clad Laminate (CCL) forms the foundation upon which all designs are built. Whether you're assembling a simple single-layer board or a complex high-speed multilayer system, understanding CCL is essential. This article offers a comprehensive guide to what CCL is, the types available, their key properties, and how they influence the performance and reliability of PCBs.

1.    What is Copper Clad Laminate (CCL)?

Copper Clad Laminate (CCL) is a composite material made by laminating copper foil onto one or both sides of a non-conductive substrate (typically fiberglass-reinforced epoxy resin, polyimide, or other dielectric materials). It serves as the "blank canvas" for PCB manufacturing, providing both mechanical support and the conductive pathways essential for electronic circuits.

During PCB fabrication, the unwanted copper is etched away, leaving behind traces, pads, and ground planes that interconnect electronic components according to the circuit design.

2.    Basic Structure of CCL

A typical CCL consists of the following layers:

⦁ Copper Foil: Provides the conductive layer.

⦁ Adhesive (in some types): Bonds the copper foil to the substrate.

⦁ Dielectric Substrate: Provides electrical insulation and mechanical stability.

In adhesiveless CCLs, particularly used for high-frequency or flexible circuits, the copper is directly laminated onto the base material without an adhesive layer to improve signal integrity.

Types of Copper Clad Laminates

CCLs are classified based on several factors such as substrate material, thermal performance, and mechanical properties. Here's a breakdown:

3.    What is Copper Clad Laminate?

Copper Clad Laminate, abbreviated to CCL, is a type of base material of PCBs. With glass fiber or wood pulp paper as reinforcing material, a copper clad board is a type of product through lamination with copper clad on either one side or both sides of reinforcing material after being soaked in resin.

It is an abbreviation for Copper Clad Laminate.

CCL is formed by lamination of copper foil onto both sides of resin impregnated glass fabric sheets. After processing the end products are electronic circuits as part of printed wiring boards.

AGC develops and manufactures a full range of RF and Digital Materials, including thermoset and thermoplastic copper clad laminates and prepreg / bondply substrates, which provide high reliability and superior thermal, mechanical and electrical performance. Thermoplastic materials are designed for critical RF/Microwave components, antennas, power amplifiers and subassemblies. Superior mechanical and electrical performance make the PTFE resin system the material of choice for your lowest loss, high frequency applications. Thermoset materials are intended for use in core routers, high speed switches, supercomputers, next-generation radio communication and applications where low signal attenuation, high reliability and high data transfer rates are critical.

Copper Clad Laminate (CCL) is a plate-shaped material made by impregnating electronic fiberglass cloth or other reinforcing materials with resin, covering one or both sides with copper foil and hot pressing, referred to as Copper clad laminate.

Various printed circuit boards of different forms and functions are selectively processed, etched, drilled, and copper plated on copper-clad boards to produce different printed circuits. The printed circuit board mainly plays the role of interconnection, insulation and support, and has a great impact on the transmission speed, energy loss and characteristic impedance of the signal in the circuit. Therefore, the performance, quality and manufacturing of the printed circuit board The processability, manufacturing level, manufacturing cost, and long-term reliability and stability depend largely on the copper clad laminate.

4.    What Makes an Excellent CCL?

CCLs only perform well when catering to performance requirements in the following aspects:

Appearance: Issues may be caused on copper foil due to unexpected elements in the manufacturing process such as dent, scratch, resin point, wrinkle, pinhole, bubble etc. All those problems will definitely lead to low performance of CCL and then PCB. Therefore, an excellent CCL should be flat and smooth in appearance.

Size: Since CCLs are base material of PCB boards, they have to conform to size requirements corresponding to PCBs. Parameters concerning the size of CCLs include length, width, diagonal deviation and warpage, each of which has to meet specific requirements.

Electric performance: This is an essential mission for a PCB so any aspect affecting its electric performance has to be carefully designed including dielectric constant (Dk), dielectric loss tangent (Df), volume resistance, surface resistance, insulation resistance, arc resistance, dielectric breakdown voltage, electric strength, Comparative Tracking Index (CTI) etc.

5.    Manufacturing Process of Copper Clad Laminate

The manufacturing process of copper clad laminate (CCL) generally involves the following steps:

Preparation of Insulating Material: The insulating material, often a type of glass fiber cloth such as FR-4, is prepared according to required dimensions.

Impregnation: The insulating material is impregnated with resin. This step involves soaking the glass fibre in a specific resin solution (like epoxy). Once soaked, excess resin is removed leaving behind uniformly impregnated sheet.

Drying and Curing: After impregnation, the material needs to be dried and partially cured ("B-staged"). This makes it rigid but still able to bond under heat and pressure.

Lamination with Copper Foil: A layer of copper foil is then laminated onto one or both sides of this base material under high temperature and pressure conditions.The heat causes further curing of the resin making it solidify , simultaneously bonding strongly with copper creating a single unified structure .

Cooling & Finishing: Post lamination assembly cools down , any extra bits are trimmed off , quality checks like visual inspection for defects or measurement for thickness etc are performed .

Cutting: Finally large sheets can be cut into smaller sizes depending upon market requirements .

6.    Manufacturing Process of CCL

The manufacturing of copper clad laminates typically involves the following steps:

⦁ Resin Preparation: Mixing and processing of epoxy, polyimide, or PTFE resins.

⦁ Substrate Impregnation: Woven fiberglass cloth or alternative materials are impregnated with resin.

⦁ Lamination: Layers of impregnated substrates are stacked, and copper foils are placed on one or both sides.

⦁ Hot Pressing: The stack is subjected to high pressure and temperature, curing the resin and bonding the copper.

⦁ Cooling and Cutting: The laminated sheets are cooled and then cut to required panel sizes.

⦁ Surface Treatment: Final treatments like anti-oxidation coatings are applied to protect the copper surface.

7.    Common Standards for CCL

⦁ IPC-4101: Specification for base materials for rigid and multilayer PCBs.

⦁ IPC-4204: Specification for flexible CCL materials.

⦁ UL 94: Flammability rating for materials.

⦁ RoHS/REACH Compliance: Environmental and safety regulations.

Manufacturers and designers must ensure the CCL material meets these standards to guarantee reliability, safety, and environmental compliance.

8.    Choosing the Right CCL for Your PCB

Selecting the appropriate CCL depends on several factors:

⦁ Operating Frequency: Higher frequencies require lower Dk and Df materials.

⦁ Thermal Management Needs: Power electronics and LEDs benefit from metal-core CCLs.

⦁ Flexibility Requirements: Flex and rigid-flex designs demand flexible CCLs.

⦁ Environmental Conditions: Exposure to moisture, chemicals, and extreme temperatures necessitates materials with higher resistance.

It is crucial to balance cost, performance, and processing requirements when selecting a CCL for your application.JLCPCB offers a wide range of reliable  materials and professional PCB manufacturing services to help you make the right choice for your project.

Conclusion

Copper Clad Laminate (CCL) is the silent yet fundamental enabler of modern electronics. Its selection profoundly impacts the electrical, mechanical, and thermal performance of a PCB. As devices continue to become smaller, faster, and more powerful, innovations in CCL materials are pushing the boundaries of what’s possible in PCB technology. Whether you're designing a simple consumer gadget or a sophisticated communication device, understanding CCL ensures a strong foundation for success.