what is fr4 in pcb?

FR4 is a common material used in the manufacturing of printed circuit boards (PCBs). It is not a specific component of a PCB but refers to the type of substrate material used for the PCB's core layer.

FR4 stands for "Flame Retardant 4." It is a grade of glass-reinforced epoxy laminate sheet material that provides several desirable properties for PCBs, including:

1. Electrical Insulation: FR4 is an excellent electrical insulator, which means it helps prevent electrical conductivity between different circuit traces on the PCB. This property is crucial for the proper functioning of electronic devices.

2. Mechanical Strength: FR4 is relatively rigid and provides mechanical strength to the PCB, which is essential for supporting components, connectors, and protecting the board from physical damage.

3. Thermal Stability: FR4 has good thermal stability, allowing it to withstand the heat generated by electronic components during operation without deforming or degrading.

4. Flame Resistance: As the name suggests, FR4 is flame-retardant, meaning it resists catching fire and helps inhibit the spread of flames in the event of a fire, which is a critical safety feature for electronic devices.

5. Dimensional Stability: FR4 has good dimensional stability, meaning it maintains its shape and size under various environmental conditions, such as changes in temperature and humidity.

FR4 PCBs are widely used in a broad range of electronic applications due to their versatility, reliability, and cost-effectiveness. The core layer of a typical multilayer PCB is often made of FR4 material, and additional layers may be added with copper traces and insulating layers to create complex circuits. The combination of FR4 and copper traces allows for the creation of intricate and reliable electronic circuits used in everything from consumer electronics to industrial equipment.