FR-4 PCB refers to a printed circuit board (PCB) that uses FR-4 as its substrate material. FR-4 is a widely used flame-retardant glass-reinforced epoxy laminate material that offers excellent electrical insulation and mechanical strength. It is the most common substrate material used in PCB manufacturing.

Here are some key features and characteristics of FR-4 PCB:

1. Electrical Insulation: FR-4 has high electrical insulation properties, allowing it to provide a reliable dielectric layer between conductive traces and components on the PCB.

2. Flame Retardancy: FR-4 is designed to be flame-retardant, meaning it has inherent resistance to fire and does not easily propagate flames. This is crucial for ensuring the safety of electronic devices.

3. Mechanical Strength: FR-4 offers good mechanical strength and rigidity, providing support and stability to the components mounted on the PCB. It can withstand mechanical stress during handling and assembly processes.

4. Dimensional Stability: FR-4 has excellent dimensional stability, meaning it retains its shape and size even under varying temperature and humidity conditions. This stability is important for maintaining the integrity and reliability of the PCB over time.

5. Thermal Resistance: FR-4 PCBs have moderate thermal resistance, allowing them to dissipate heat to some extent. However, for applications that require higher thermal management, additional measures like metal core PCB or heatsinks may be necessary.

6. Cost-Effective: FR-4 is a relatively affordable material, making FR-4 PCB cost-effective for a wide range of applications.

FR-4 PCB are suitable for a variety of electronic devices and applications, including consumer electronics, telecommunications equipment, industrial controls, automotive electronics, and more. They can be manufactured in both single-sided and multilayer configurations, depending on the complexity of the circuit design.

It's important to note that FR-4 is available in different grades, such as FR-4 Standard, FR-4 High-Tg (High Glass Transition Temperature), and FR-4 Halogen-Free, each with specific properties and performance characteristics. The selection of the appropriate grade depends on the specific requirements of the PCB design and the desired performance parameters.