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FR4 is a standard for glass fiber-reinforced epoxy resin compounds defined by the National Electrical Manufacturers Association (NEMA).
The "FR" stands for "flame retardant," indicating that the material meets the UL94V-0 flammability standard for plastics. The code 94V-0 is marked on all FR-4 printed circuit boards (PCBs). When exposed to fire, the FR-4 material is designed to prevent the fire from spreading and ensures it extinguishes quickly.
The glass transition temperature (TG) for high TG or HiTG FR-4 ranges from 115°C to 200°C, depending on the manufacturing method and resin used. A standard FR-4 PCB typically consists of one FR-4 layer sandwiched between two thin copper layers.
FR-4 incorporates bromine, a halogen that enhances fire resistance, and serves as a replacement for G-10, which generally has lower resistance in most applications.
The advantages of FR-4 include its favorable strength-to-weight ratio, resistance to water absorption, ability to withstand high mechanical loads, and excellent insulating properties in both dry and wet environments.
FR4 Materials and Properties
Examples of FR-4 Types:
- Standard FR-4: This variant has a heat resistance of approximately 140°C to 150°C.
- FR-4 High TG: This type has a high glass transition temperature (TG) of 180°C.
- FR-4 High CTI: This variant features a comparative tracking index greater than 600 volts (also known as IRC in France, which refers to the insulation resistance index).
- FR-4 Without Copper Laminate: This is ideal for insulation boards, forms, and clips.
Thickness Considerations:
- SMT Assembly and Component Compatibility: Although FR-4 is widely used for various PCBs, its thickness affects component compatibility. For instance, through-hole technology (THT) components require different thicknesses compared to surface-mount technology (SMT) components.
- Space Saving: In electronic design, especially for USB connectors and Bluetooth devices, space economy is essential. Thinner PCBs are preferable in configurations where space is a constraint.
- Design and Flexibility: Most manufacturers prefer thicker boards, as excessively thin FR-4 substrates risk cracking when the card size increases. Thicker boards are more flexible and suitable for creating "V-grooves."
- Environmental Considerations: The intended environment for the PCB should be taken into account. For example, in medical electronic control units, thinner PCBs can reduce stress. However, excessively thin (and thus flexible) boards may be more sensitive to heat and could warp during soldering.
- Impedance Control: The thickness of the board affects the dielectric thickness of FR-4, which makes impedance control significantly easier. When impedance is a critical factor, the board's thickness must be carefully considered.
- Connections: The type of connectors used for printed circuits also influences the required thickness of the FR-4 material.
Reasons for Choosing FR-4:
FR-4 is a popular choice for low-volume production and electronic prototypes due to its low cost. However, it may not be suitable for high-frequency printed circuits. For products requiring components that are not easily adaptable or compatible with rigid PCBs, alternative materials such as polyimide/polyamide should be considered.
Why Choose China PCBA Supplier KSPCBA as Your FR4 Materials Manufacturer?
– Experienced and skilled team
– State-of-the-art equipment
– Strict quality control
– Excellent customer service
– Competitive price
Please send Email to kspcba@c-alley.com or call us through +86 13828766801 Or submit your inquiry by online form. Please fill out below form and attach your manufacturing files( PCB Gerber files and BOM List) if need quotation. We will contact you shortly.