The copper-clad laminate (CCL) comprises a substrate, copper foil, and adhesive. The substrate is an insulating layer board made of polymer synthetic resin and reinforcing materials. A layer of pure copper foil with high conductivity and good weldability is coated on the surface of the substrate, commonly with thicknesses of 18μm, 35μm, or 50μm. CCL with copper foil only on one side of the substrate is called single-sided CCL, while CCL with copper foil on both sides is called double-sided CCL. The adhesive ensures that the copper foil adheres firmly to the substrate. Common thicknesses of CCL include 1.0mm, 1.5mm, and 2.0mm.
Types of CCL
- According to mechanical rigidity, CCL can be divided into rigid copper-clad laminate (Rigid Copper Clad Laminate) and flexible copper-clad laminate (Flexible Copper Clad Laminate).
- Based on different insulating materials and structures, CCL can be categorized into organic resin CCL, metal-based CCL, and ceramic-based CCL.
- CCL can be classified by thickness into thick boards (ranging from 0.8 to 3.2mm, including Cu) and thin boards (less than 0.78mm, excluding Cu).
- In terms of reinforcing materials, CCL can be grouped into glass cloth-based CCL, paper-based CCL, and composite-based CCL (CME-1, CME-2).
- CCL can be divided into flame-retardant and non-flame-retardant types based on flame retardancy ratings.
- According to UL standards (UL94, UL746E, etc.), rigid CCL can be classified into four flame retardancy ratings: UL-94V0, UL-94V1, UL-94V2, and UL-94HB.
Common Types and Characteristics of CCL
- Copper-clad phenolic paper laminate is a laminated product made by impregnating insulating impregnated paper (TFz-62) or cotton fiber impregnated paper (1TZ-63) with phenolic resin and hot-pressing. One or both surfaces of the laminate can be attached with a single sheet of alkali-free glass impregnated cloth, with copper foil on one side. It is mainly used as a circuit board in radio equipment.
- Copper-clad phenolic glass cloth laminate is a laminated product made by impregnating alkali-free glass cloth with epoxy phenolic resin and hot-pressing. It has copper foil on one or both sides, featuring lightweight, good electrical and mechanical properties, and easy processing. Its surface is light yellow, and if cyanamide is used as the curing agent, the surface will be light green with good transparency. It is mainly used as a circuit board in radio equipment with higher operating temperatures and frequencies.
- Polytetrafluoroethylene copper-clad laminate is made by hot-pressing polytetrafluoroethylene board as the substrate with copper foil. It is mainly used as a circuit board in high-frequency and ultrahigh-frequency circuits.
- Epoxy glass cloth copper-clad laminate is a commonly used material for plated-through-hole circuit boards.
- Flexible polyester copper-clad film is a strip material made by hot-pressing polyester film with copper. In application, it is curled into a spiral shape and placed inside the equipment. To reinforce or protect against moisture, it is often perfused with epoxy resin to form a single unit. It is mainly used as a flexible circuit board and printed cable, serving as a transition line for connectors.
Currently, CCL supplied in the market can be mainly classified into the following types based on the substrate: paper substrate, glass fiber cloth substrate, synthetic fiber cloth substrate, non-woven fabric substrate, and composite substrate.
Common Materials for CCL Production
FR-1 – Phenolic cotton paper (more economical than FR-2)
FR-2 – Phenolic cotton paper
FR-3 – Cotton paper, epoxy resin
FR-4 – Woven glass, epoxy resin
FR-5 – FR-4 – Woven glass, epoxy resin
FR-6 – Matte glass, polyester
G-10 – Woven glass, epoxy resin
CEM-1 – Cotton paper, epoxy resin (flame-retardant)
CEM-2 – Cotton paper, epoxy resin (non-flame-retardant)
CEM-3 – Woven glass, epoxy resin
CEM-4 – Woven glass, epoxy resin
CEM-5 – Woven glass, polyester
AIN – Aluminum nitride
SIC – Silicon carbide
