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What Is the Difference Between FR4 and FR5 PCB?

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Printed circuit boards, also referred to as PCBs, are the foundation and circuits and electronics in modern electronic gadgets. Because of their remarkable performance and cost-effectiveness, FR4 and FR5 are the most often utilized substrates among the numerous materials used to produce PCBs. In this post, we will look at the differences amongst FR4 as well as FR5 PCBs, or as well as their distinct features and uses.

Difference Between FR4 And FR5 PCB

1. content and Material:

 Both FR4 and FR5 are glass-reinforced epoxy laminates, although the type and content of the reinforcement material differs. FR4 is made of woven fiberglass fabric impregnated using a flame-resistant epoxy resin, resulting in a strong and long-lasting laminate. 

FR5, on the other hand, is a better-grade woven fiberglass fabric with a more modern epoxy resin system that makes it additionally strong and capable for withstanding more extreme temperatures and mechanical loads.

2. Thermal Performance: 

One of the primary distinctions amongst FR4 and FR5 Shenzhen PCB Assembly Factory is their thermal performance. Because FR4 is composed of a lower glass transformation temperature (Tg), often between 135°C and 150°C, it may lose structural integrity as well as electrical characteristics at high temperatures. 

3. Mechanical Strength:

 The mechanical properties of FR4 and FR5 are unique. When compared to typical FR4 laminates, FR5 PCBs have superior tear strength, flexural strength, as well as impact resistance. As consequence, FR5 boards are fewer prone to mechanical strains, which is especially beneficial in applications whereby the PCBs may be tested with vibrations as well as mechanical shock.

4. Dielectric Properties:

 The dielectric constant (Dk) along with dissipating factor (Df) are important factors in high-frequency along with high-speed applications because they influence signal integrity. While Dk values for FR4 and FR5 are similar, Df values for FR5 PCBs are lower, indicating lower signal losses and greater transmission of signal capabilities, specifically at higher frequencies.

5. Cost:

 Because of variations in substance composition and manufacturing procedures, FR4 is less expensive than FR5. While FR5 offers improved performance, the additional benefits come at a higher cost, allowing FR4 a more appealing option for cost-conscious enterprises.

6. Applications:

FR5 PCBs, on the other hand, find a home in applications that are more complicated including aircraft, high-speed communication equipment, and modern military electronics. Because of its improved thermal and mechanical qualities, FR5 is ideal for mission-critical applications requiring excellent reliability and performance under harsh conditions.

Why in the world are FR-4 along with FR-5 PCB substrates so popular?

There are numerous substrate materials utilized in Shenzhen PCB Assembly Factory manufacturing. Water-resistant, flame-resistant, and robust, FR-4 and FR-5 boards provide superior insulation amongst copper layers. This reduces electromagnetic interference and promotes signal integrity. UL94-V0 is their flammability rating.


 FR4 and FR5 happen to be extensively utilized materials in the manufacturing of printed circuit boards business, although they serve different purposes. While FR4 provides good performance at a reduced cost, FR5 has improved thermal and mechanical qualities, making it appropriate for high-performance applications that operate under harsh conditions.

Choosing between the two is determined by the project’s specific needs, budget limits, and desired performance level. New materials may develop as technology advances, but for the time being, FR4 and FR5 remained foundations of PCB design and manufacture.