Printed circuit boards come in different materials known as substrate, including copper-clad laminate or CCL. PCB substrates are either organic or inorganic, depending on their properties. The organic substrates come up in different materials known as the reinforced board, such as glass felt, fiberglass, fiber paper, fiber cloth, and so on.
PCB fabricators impregnate there in forcing materials with an adhesive called resin, making it dry, and then cover it with copper foil at high pressure and temperature. Such a substrate is CCL or copper-clad laminate that resides on either one or both sides of the board. So, CCL is either single-sided or double-sided.
Rigid PCB has a rigid CCL with a substrate, such as
- Resin epoxy FR4
- Aluminum or copper
These materials help make different types of PCBs, including single, double, and multilayer PCBs.
Engineers define the CCL standard specification with ASTM D1867 and develop their circuit boards according to these standards. To cover twelve grades of CCL, ASTM needs the laminates to meet certain factors for peel strength, like
- High temperatures
- Volume resistivity
- Water absorption
- Flammability ratings
- Dielectric breakdown
- Lengthwise and crosswise strength
The PCB Manufacturer should also check the CCL for twist, warp, or blistering. CCL manufacturers often follow the IPC-410IC as a standard. Moreover, they use IPC-IM650 to test the fabricated CCL.
FF4 CCL: As discussed above FR4 is a popular material for copper-clad laminate. The material is resin epoxy, and it is ideal for rigid circuit boards. You will see it on both sides and only one side of the board. The material is a combination of epoxy resin and fiberglass cloth. Resin makes the board fire resistant that’s why we abbreviate it as FR or flame retardant. However, it has to pass through testing to see if it is according to the UL94V-0 standards.
Copper base: like aluminum CCL, copper core CCL has a copper plate, copper foil, and dielectric layer for bonding. PCB’s thermal dissipation and dielectric bonding determine the overall thermal conductivity.
PCB with copper substrate has three types, depending on its design, such as copper without PTH, COB, or chip-on-board copper circuit board which is without the thermal pad insulation.
Aluminum CCL: Copper-clad laminate also has aluminum as a base material combined with a dielectric layer and copper foil. These materials are bonded through hot pressing and very high temperatures. The dielectric bonding determines the thermal conductivity of the aluminum core laminate. However, both copper foil and dielectric have high conductivity, and manufacturers often use ceramic to fill the dielectric layer.
What Is RF, Radio Frequency CCL?
The RF CCL is also known as the Microwave PC Board CCL as the board has microwave frequencies. Such a circuit board has certain characteristics to consider, such as
- DK, dielectric constant
- DF, dissipation factor
- CTE, coefficient of thermal expansion
- TCDR thermal coefficient of dielectric constant
- Thermal conductivity
It involves high-frequency materials of which PTFE is a common practice. It is a synthetic material having great dielectric properties at high frequencies which are also known as microwave frequencies. A few companies develop the high-frequency PCB CCL, including Isola, Rogers, Taconic, and Panasonic.
What is Prepreg in CCL?
Prepreg or pre-impregnated CCL is a kind of fiberglass that is impregnated with a bonding material such as resin. The resin is not hard, however, it is dry and gets sticky when heated. In other words, the fiberglass is made strong through an adhesive just like FR4.
Prepreg materials come up in different thicknesses that determine their quality, such as standard resin, SR, medium resin, MR, or, high resin, HR. The PC Board manufacturer use the resin thickness according to the type of PCB they require.
CCL PCB Applications
PCB with copper clad laminate is ideal for:
- Electronics PCBs
- High-speed communication devices, like 4G,5G, and LTE
- Automotive products, such as ADAS radar
- Avionics Radar
- Welded tanks
- Offshore platform shearing
- Steam condenses
- Pressure vessels
- Heat exchangers
- Missile components
- Hydraulic bushings
The above applications related to communications are essential to communicate faster, such as 4G helps you download anything within seconds. Whereas 5G is much faster, in this case, and you can see it by comparing it with the old and low-speed communication devices.
How To Identify The Best CCL PCB
A few parameters help you find if the copper-clad PCB is the best or not, such as size, neatness or appearance, chemical properties, performance according to the environment, as well as a physical performance.
PCB Design Parameters Including Size: The size of the CCL matters a lot in PCB design as it’s the base material. The quality of the end product also depends on the thickness of the core material. At the same time, you have to consider other parameters, including length, width, wattage, and diagonal deviation. Each design parameter should meet the necessary standards to have an ideal product that performs well.
CCL Appearance: several issues happen during Printed Circuit Board manufacturing that can affect the appearance of the copper foil. Such as dents, pinholes, scratches, resin points, bubbles, wrinkles, etc. These issues also slow down the PCB CCL performance.
Environmental Compatible: Copper-clad laminate PCB should be compatible with the environment. Like, it should resist water and corrosion or its production will get slow, resulting in serious issues.
Chemical Function: The chemical properties of copper-clad laminate are also vital and should be according to the standards in terms of flammability. The Z-CTE or, Z-axis coefficient of thermal expansion, Tag, chemical resistance, and dimensional stability has to be considered.
Physical Function: Copper-clad laminate has to meet certain physical requirements, including the PS or peel strength, bending strength, dimensional balance, heat resistance, as well as punching. It should resist thermal stress.
Electric Property: Copper-clad laminate should electrically perform high, as it’s very important. As described above, copper-clad laminate PCB should strictly meet certain requirements, such as DF, DK, insulation resistance, CTI or comparative tracking index electric strength, arc resistance, and volume resistance.
How Many Types Of Copper Clad Laminate Are There?
You can classify the copper-clad laminate according to different factors, such as size, thickness, mechanical material, structure, insulation material, types of reinforcement, resin type, and CCL performance.
Copper-clad laminate is either rigid or flexible of which rigid CCL is further divided, depending on its combination materials. It is either single or double-sided, besides there are also special rigid CCL PCBs with a high-flame resistance and other properties.
Flexible CCL: It includes,
- Non-flame retardant polyester
- Flame retardant polyester
- Polyimides with and without flame retardant
- Fiberglass cloth of small thickness
Benefits of Flexible Copper Clad Laminate
- The FCCL has many benefits, such as
- It has great flexing power
- It is ECO friendly
- It is free from halogen
- Better heat resistance
- Great adhesive properties
- it is a blend of different copper clad thickness
Special copper-clad laminate has ceramic and it’s also called ceramic CCL. It has different materials, such as aluminum oxide, aluminium it ride, silicon carbide, boron nitride, and beryllium oxide.
What is the manufacturing process of CCL?
Copper-clad laminate has complex manufacturing, including rolled copper foil that acts as a conductive material. PCB fabricators impregnate the reinforcing materials with an adhesive called resin, making it dry, and then cover it with copper foil at high pressure and temperature.
What Are The Uses Of CCL PCB?
Copper-clad laminate is fiberglass mixed with resin and glass and it is on either one or both sides of the glass fabric. Engineers use it to develop radios, mobile devices, televisions, computers, digital devices, and other multiple electronics.
What Is Copper Foil In CCL?
Copper foil in CCL is a cathodic electrolytic material that lies on the metal foil in a PCB. The material is easy to bond with the insulating layer to provide a protective covering. It is also easy to corrode to make a circuit protector.
What are CCL Standards?
Copper-clad laminate standard specifications are defined with ASTM D1867 and engineers develop their circuit boards according to these standards. To cover twelve grades of CCL, ASTM needs the laminates to meet certain factors for peel strength.
The fabricators should also check the CCL for twist, warp, or blistering. Copper-clad laminate manufacturers often follow the IPC-410IC as a standard. Moreover, they have to use IPC-IM650 to test the fabricated CCL.
PCB different materials known as substrate, including copper clad laminate or CCL. PCB substrates are either organic or inorganic, depending on their properties. The organic substrates come up in different materials known as reinforced boards, such as glass felt, fiberglass, fiber paper, fiber cloth, and so on.
PCB fabricators impregnate the reinforcing materials with an adhesive called resin, making it dry, and then cover it with copper foil at high pressure and temperature. Such a substrate is CCL or copper-clad laminate that resides on either one or both sides of the board.
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