As electronic products continue to become smaller, faster, and more highly integrated, the materials used to manufacture printed circuit boards have become increasingly important. From simple single-sided boards to high-density multilayer and HDI structures, different applications require different material properties.

Understanding PCB Materials and their corresponding material codes helps designers, engineers, purchasers, and manufacturers select the right substrate for electrical performance, mechanical strength, thermal reliability, and cost requirements.

So, what types of materials are commonly used on a PCB, and what do their codes mean?

What Are PCB Materials?

PCB Materials are the substrates and insulating materials used to construct a printed circuit board. They provide mechanical support for copper circuits and electrical insulation between conductive layers.

A typical PCB may contain several material components, including:

• Copper foil
• Resin systems
• Glass fiber reinforcement
• Paper-based reinforcement
• Prepreg
• Core materials
• Solder mask
• Surface finish materials

The choice of material directly affects important PCB characteristics such as dielectric performance, thermal resistance, mechanical strength, dimensional stability, moisture resistance, signal integrity, and manufacturing cost.

As PCB technology has developed from single-layer structures to multilayer, high-density, and high-frequency designs, material selection has become an increasingly important part of PCB engineering.

Common PCB Material Types and Codes

Different PCB substrates are identified by material families and specifications. Several common materials are described below.

1. 22F Single-Sided Composite Material

22F is a paper-based composite substrate commonly associated with lower-cost single-sided PCB applications.

This type of material is generally suitable for relatively simple electronic products where electrical and thermal requirements are moderate.

Depending on the board design and manufacturing requirements, drilling methods may vary. More demanding production applications can use CNC drilling equipment to improve hole accuracy and consistency.

2. CEM-1 Single-Sided Composite Material

CEM-1 is a composite epoxy material commonly used for single-sided PCBs.

Compared with conventional paper-based substrates, CEM-1 provides improved mechanical and electrical performance while maintaining relatively low manufacturing costs.

Typical applications include:

• Consumer electronics
• Simple control circuits
• Household electronic products
• Low-cost electronic devices

CEM-1 is generally more economical than FR-4 when the application does not require the higher performance provided by a glass-epoxy multilayer material.

3. CEM-3 Double-Sided Composite Material

CEM-3 is a composite substrate commonly used for cost-sensitive double-sided PCB applications.

It generally uses a glass-fiber-based structure combined with resin and other reinforcing materials. Compared with traditional paper-based substrates, CEM-3 offers better mechanical properties and dimensional stability.

For relatively simple double-sided PCB designs, CEM-3 can provide a balance between performance and cost.

4. FR-4 Epoxy Glass-Fiber Material

FR-4 is one of the most widely used PCB substrate materials.

It is based on glass-fiber reinforcement combined with an epoxy resin system. Because of its good mechanical strength, electrical insulation, thermal performance, and relatively stable manufacturing characteristics, FR-4 is widely used in single-sided, double-sided, and multilayer PCBs.

Typical applications include:

• Industrial electronics
• Consumer electronics
• Communication equipment
• Automotive electronics
• Computer hardware
• Power control equipment
• Embedded electronic systems

Different FR-4 material grades can have different thermal and electrical properties. Therefore, designers should select the appropriate material according to the operating environment and application requirements rather than treating all FR-4 materials as identical.

What Is Prepreg?

Prepreg is short for pre-impregnated material. It is a glass-fiber reinforcement material impregnated with resin and partially cured.

In multilayer PCB manufacturing, Prepreg is placed between copper layers or core materials and then laminated under controlled temperature and pressure.

During lamination, the resin flows and cures, bonding the different layers together while providing electrical insulation.

Common prepreg styles include:

• 1080
• 2116
• 7628

Different glass styles have different thicknesses, resin contents, and characteristics. Manufacturers select the appropriate combination based on the required finished board thickness, dielectric properties, copper structure, and stack-up design.

Therefore, Prepreg is not simply an insulating sheet. It is an important component of multilayer PCB stack-up design.

PCB Flame-Retardant Classification

PCB substrate performance is also affected by its flame-retardant characteristics.

The UL-94 standard is commonly referenced when evaluating the flammability behavior of polymeric materials. Common classifications include:

• UL-94 V-0
• UL-94 V-1
• UL-94 V-2
• UL-94 HB

These classifications describe different levels of flame behavior under specified test conditions.

It is important to understand that UL-94 classification is a flammability rating, not a complete description of the electrical or thermal performance of a PCB substrate.

For applications with strict safety requirements, designers should verify the actual material datasheet and applicable product safety standards.

What Do PCB Material Codes Mean?

PCB Material Codes help identify the general material family or construction used for a board.

For example:

The exact material properties depend on the manufacturer, resin system, glass style, thickness, and material grade.

Consequently, a material code should not be used as a substitute for reviewing the manufacturer’s technical datasheet.

Why Does PCB Material Selection Matter?

The substrate has a direct influence on PCB performance and manufacturing reliability.

Electrical Performance

The dielectric constant and dissipation factor of the material influence signal transmission, impedance control, and high-frequency performance.

For high-speed or RF applications, material selection becomes especially important because conventional low-cost substrates may not provide the required electrical characteristics.

Thermal Performance

The PCB must withstand the temperatures generated during soldering, assembly, and normal operation.

Material parameters such as glass transition temperature (Tg), decomposition temperature (Td), and thermal expansion characteristics should therefore be considered for demanding applications.

Mechanical Reliability

The substrate provides structural support for copper layers, components, and plated holes.

A material with appropriate mechanical strength and dimensional stability can help reduce problems caused by thermal cycling, vibration, and mechanical stress.

Moisture Resistance

Moisture absorption can affect insulation characteristics and reliability. For products operating in humid environments, material selection and storage conditions should be carefully controlled.

Manufacturing Compatibility

Not every PCB material is suitable for every manufacturing process.

Material selection can affect:

• Drilling
• Laser processing
• Plating
• Etching
• Lamination
• Soldering
• Surface finishing
• Dimensional control

Manufacturers must therefore consider both electrical requirements and manufacturing capabilities when selecting materials.

PCB Material Development Trends

The development of PCB Materials is closely related to the evolution of electronic technology.

Modern PCB development is moving toward:

• Higher wiring density
• Smaller feature sizes
• Finer lines and spaces
• Smaller microvias
• Higher layer counts
• Better dimensional stability
• Higher thermal reliability
• Improved high-frequency performance
• Lower dielectric loss
• Greater reliability
• Lighter and thinner PCB structures

High-speed communication, 5G infrastructure, automotive electronics, artificial intelligence hardware, data centers, and advanced industrial equipment are increasing demand for specialized PCB materials.

For high-frequency and high-speed applications, low-loss materials with controlled dielectric properties are becoming increasingly important.

PCB Manufacturing and Material Selection

Material selection should be considered together with PCB design and manufacturing requirements.

For example, a simple single-sided consumer PCB may prioritize cost efficiency, while a multilayer communication board may require tighter control of dielectric thickness, impedance, thermal performance, and dimensional stability.

During PCB development, engineers should evaluate:

1. Electrical requirements
2. Operating temperature
3. Layer count
4. Board thickness
5. Copper thickness
6. Required impedance
7. Manufacturing process
8. Reliability requirements
9. Environmental conditions
10. Overall cost

A well-designed material system can help reduce manufacturing problems and improve the long-term reliability of the finished PCB.

How Kingda Uses PCB Material Selection to Support Manufacturing

As a professional PCB manufacturer, Kingda supports a range of PCB manufacturing requirements, including double-sided and multilayer PCBs, HDI boards, thick-copper PCBs, blind and buried vias, high-frequency PCBs, PCB prototyping, and volume production.

Material selection is evaluated together with PCB structure, layer stack-up, copper thickness, via technology, electrical requirements, and manufacturing processes.

This integrated approach helps ensure that the selected PCB Materials are compatible with both the electrical design and the manufacturing process.

Conclusion

Understanding PCB Materials and PCB Material Codes is essential for selecting the right substrate for an electronic product.

Materials such as FR-4, CEM-1, and CEM-3 serve different applications, while Prepreg plays an essential role in multilayer PCB lamination. Meanwhile, UL-94 classifications provide important information about material flammability characteristics.

As electronic products continue to move toward higher density, higher speed, smaller dimensions, and greater reliability, PCB material selection will become even more important.

For designers and manufacturers, the best material is not necessarily the most expensive one. Instead, it should provide the right balance of electrical performance, thermal reliability, mechanical properties, manufacturability, and cost for the specific application.