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What is the difference between FR3 and FR4?
Knowledge Base + 2024.01.09

FR3 and FR4 are both types of printed circuit board (PCB) materials, each with its own set of properties. These materials are used in the construction of electronic circuits. Here are the key differences between FR3 and FR4:

  1. Material Composition:

    • FR3: FR3 is a type of PCB material made from a composite of cellulose paper impregnated with a phenol formaldehyde resin. It is known for its good electrical insulation properties and is commonly used in low-cost applications.

    • FR4: FR4 is a more widely used and versatile PCB material. It is made from woven glass fabric impregnated with an epoxy resin. FR4 is known for its excellent mechanical strength, flame resistance, and good electrical insulating properties.

  2. Mechanical Properties:

    • FR3: FR3 has moderate mechanical strength. It is suitable for applications where the mechanical requirements are not too demanding.

    • FR4: FR4 is known for its high mechanical strength and stability. It provides good dimensional stability, making it suitable for applications where the board may experience mechanical stress.

  3. Thermal Properties:

    • FR3: FR3 typically has lower thermal resistance compared to FR4. It may have limitations in terms of the maximum operating temperature it can withstand.

    • FR4: FR4 has higher thermal resistance, allowing it to withstand higher temperatures. This makes FR4 suitable for applications where heat dissipation is a consideration.

  4. Applications:

    • FR3: FR3 is often used in low-cost, general-purpose applications where high mechanical or thermal performance is not critical. It may find applications in consumer electronics, lighting, or other areas where cost is a significant factor.

    • FR4: FR4 is widely used in various electronic applications, including telecommunications, computing, industrial controls, and automotive electronics. Its combination of electrical, mechanical, and thermal properties makes it suitable for a broad range of applications.

  5. Cost:

    • FR3: FR3 is generally less expensive than FR4. Its lower cost makes it attractive for budget-conscious applications.

    • FR4: FR4 may be more expensive than FR3, but its versatility and superior performance make it a preferred choice in many electronic applications where reliability and durability are crucial.

In summary, FR3 and FR4 are different PCB materials with distinct properties. FR3 is often used in cost-sensitive applications, while FR4 is a versatile and widely used material that provides better mechanical strength, thermal resistance, and reliability, albeit at a potentially higher cost. The choice between FR3 and FR4 depends on the specific requirements of the electronic application.