PCB Substate Materials: Everything You Should Know About

Explore the world of PCB substrates with our comprehensive guide! Learn about the crucial role PCB substrates play in electronic devices, the types of materials available, and their impact on thermal, mechanical, and electrical properties.
Best PCB Substrate Materials for your PCB

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Have you ever wondered how circuit boards are made up? Just like every home needs a base, every circuit board needs a foundation, which is called a PCB Substrate. Everything that requires support in PCB, like traces, is included in the PCB substrate. So, basically speaking, without the PCB substrate, there is no PCB and, thus, no electronic devices and innovations.

In this article, we will see about the PCB substrate, its type, use cases, pros and cons of each type, and the factors to consider while selecting the right PCB substrate based on your requirements.

What is PCB Substrate Materials?

PCB Substrate is the base material or the insulation layer where the PCB is designed and developed. They are dielectric compost structures. It comprises of epoxy resin with copper on one or two sides.

The selection of PCB materials is essential as it directly influences the circuit board’s thermal, mechanical, and electrical properties. For example, if you are searching for better thermal properties of your board, then you can choose a ceramic-based substrate

Similarly, if you are searching for durability and strength in PCB, then rigid PCB substrate is there to help you out. On the other hand, the flexible substrate materials provide more design options to the engineers.

Key Properties of PCB Substrate Materials

PCB Substrate Materials with ElePCB Logo

The operations and duration of PCB depend on the selection of substrates and PCB materials. The PCB materials should provide high reliability and strength for the durable performance of electronic circuits. The major features that determine the quality of PCB substrate materials are as follows:

Dielectric Constant

It shows how well it can store electrical energy in an electric field. It influences the speed of signal transmission on the PCB. The lower dielectric constant indicates the higher signal transmission speed on the circuit board. For high-frequency applications, the lower dielectric constant is often preferred.

Thermal Properties

It is the ability of a material to conduct heat. 

Thermal properties of materials influence the efficiency of heat dissipation from the components. It includes transition temperature, thermal conductivity, and the coefficient of thermal expansion. The higher transition temperature provides better heat stability on the device. 

Lower CTE is preferred for reducing mechanical stress. Finally, higher thermal conductivity helps to dissipate the heat effectively. 

Mechanical Properties

It determines the tensile strength, rigidity, and flexibility of the PCB materials. The measure of the substrate’s mechanical is influenced by the reliability and durability of the PCB. The resistance of breaking under pressure is defined by tensile strength. The PCB’s resistance to deformation determines the Rigidity of the PCB. At the same time, the flexibility is useful for the bendable use cases.

Types of PCB Substrate Materials

Types

There are various types of PCB base materials used in circuit boards. Each one has various sets of properties. Let’s look into some of the common PCB Substrate Materials:

Flame Retardant 4

It is one of the most common and versatile PCB substrate materials. It provides excellent electrical insulation properties. The major composition of FR-4 material is glass-reinforced epoxy laminate. It is known for:

  • High dielectric strength
  • Wide application area
  • Greater moisture resistance
  • Lower Cost with excellent work performance

FR-4 PCB materials are mostly used in consumer electronics, telecommunication, and industrial applications. It is the first choice for most of the standard PCBs. Its stability and cost-effectiveness make it the first choice of many industries.

Pros

  • It offers better mechanical strength and electrical properties.
  • It exhibits better dielectric strength.

Cons

  • It may not be the best option for extreme environments.
  • It offers limited heat dissipation for thermal management. 

Flame Retardant 2 (FR-2)

It is the next cost-effective PCB substrate materials. However, it shows lesser performance than FR 4 materials. It offers modern thermal properties, which makes it suitable for low to medium-frequency applications. Besides, it allows an easy manufacturing process. 

Cons

  • It offers limited performance and thus is not suitable for high-frequency applications. 
  • It also has limited thermal capacity.

Composite Epoxy Material (CEM-1)

It is another choice in PCB substrate materials. It’s a composite material with woven glass fabric impregnated with epoxy resin. It provides better electrical properties compared to FR-2. Also, it is easier to use during the manufacturing process.

CEM-1 is widely used in single-sided PCBs, LED lighting systems, automotive applications, etc.

Pro

  • It offers better and improved mechanical strength as compared to FR-2.
  • It is used for a wide range of applications. 

Cons

  • The limited mechanical properties make it suitable for single- or double-sided PCBs. 
  • It is not an ideal option for high-frequency designs. 

PTFE (Teflon)

Teflon is known as the high-performance PCB substrate material. It is popular for its better thermal and electrical properties. Its lower dissipation factor and dielectric constant make it an excellent choice for high-frequency applications. Besides, its other applications include radar systems, aerospace, military, and high-end circuitry. It provides minimal signal loss with reliability.

Pro

  • It offers resistance to various chemicals.
  • It maintains proper electrical and thermal properties.
  • It is light and offers better mechanical strength. 

Cons

  • It is more expensive than other PCB substrate materials.
  • The manufacturing process is a bit challenging and complex.

Factors to Consider While Selecting the Right PCB Substrate Materials

PCB Materials Selection Guides

It is important to select the right PCB substrate materials based on your requirements. Let’s consider some significant factors when selecting the right PCB substrate materials. 

  • Identify the specific requirements of your project.
  • Choose materials with good heat conductivity for efficient heat dissipation.
  • Determine the strength needed to withstand physical stress.
  • Look for a lower dielectric constant for faster signal transmission.
  • Decide if your project requires a flexible or rigid substrate.
  • Consider the budget and select a substrate that aligns with it.
  • Understand the properties of common materials like FR-4, FR-2, and CEM-1.
  • Ensure the substrate material is compatible with the rest of the components.
  • Stay updated about emerging trends and innovations in PCB substrates.
  • Consult with experts or manufacturers for guidance based on your project specifics.

Difference Between PCB and Substrate

Feature

Printed Circuit Board (PCB)

Substrate

Definition

A board with conductive path and traces for electronic components and circuits.

The base material or insulating layer where PCBs are constructed.

Function


Provides mechanical and electrical properties for electronic components.

Serves as the foundation for the PCB and affects its electrical, thermal, and mechanical properties.

Composition

Consists of layers of substrate material and conductive traces (usually copper) that form the circuits.

Depending on the application requirements, it can be made from various materials like FR-4, polyimide, ceramics, etc.

 

Trends and Innovations in PCB Substrate

Low Dk/Df

Materials with lower dielectric constant and dissipation are not a new topic, but they have become a spotlight in the PCB industry. The lower Dk and Df are perfect choices for high-frequency applications, resulting in minimal signal loss.

3D Printed Substrate

The rise of 3D-printed substrates is a new topic in the PCB industry today. In the electronic market, customized shapes and designs are a growing need that makes work easier and quicker. 

Nanocomponents

Nanocomposite substrate is taking the lead in the present day, and it’s going to change the world in the future. The nano substrate materials are booming because of their enhanced mechanical and thermal properties for smaller and more robust electronics.

Conclusion

PCB substrate is the foundation of the circuit board. The various types of PCB substrates offer various properties. It can be used based on your specific requirements. If you are wondering which PCB substrate is suitable and can’t figure it out for your application, you can contact ElePCB for all your PCB solutions. We are a trustworthy PCB manufacturing company with a team of engineers, designers, and other subject matter experts. 

FAQs

What is PCB Substrate made of?

PCB substrates are made up of various dielectric composites. One of the base materials includes epoxy resin with copper layers in one or both layers. The selection of PCB substrate material directly impacts the circuit board’s mechanical, thermal, and electrical properties.

What is the best substrate for PCB?

The selection of the best substrate for PCB depends on the specific application requirement. FR-4 is used for its cost-effectiveness and versatility. However, specialized applications like RTFE could be the best option because of their high-performance nature, especially in high-frequency and demanding environments.

Can PCB substrate be used for flexible or rigid-flex PCBs?

Yes, PCB substrate can be used for flexible and rigid Flex PCBs. For Flexible PCBs, there is a certain substrate material like polyamide. Rigid-flex PCBs combine rigid and flexible substrates for applications requiring versatility in form and fit.

How does the thickness of the PCB Substrate impact the performance?

The thickness of the substrate could affect the signal integrity, impedance control, and strength of the PCB. Thicker PCB substrate provides better mechanical strength while requiring more parasitic capacitances.

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Rashila
Rashila
I am an Electrical and Electronics Engineer, and I have 5 years of work experience with electronics and communication jobs. I'm the full time content creator of ELE company.
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Michael is the general manager of ELE PCB, a leading PCB design and manufacturing company based in China. He has over 10 years of experience in the PCB industry, and has been involved in various projects.

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