What is Fr4 PCB？

Fr4 PCB is a type of printed circuit board (PCB). It is made from a flame-resistant epoxy resin and glass fabric. It sticks well to copper foil and doesn’t absorb much water, which makes it great for common uses.

Fr4 stands for flame retardant and it meets the condition of UL94V-0, it is used as a copper-coated material for double-layer PCBs, or as a prepreg and core for multilayer.

Fr4 is the foundation material upon which most hard circuit boards are built. Yet many lack the knowledge of what Fr4 is, not to talk of why it is the most popular PCB base. Continue reading to learn more about FR4, what they are, why they are so popular, and how their qualities compare to others within the industry.

What is Fr4 Material in PCB Manufacturing?

Fr4 can also be written as FR-4, which is a name and a standard rating. The term also refers to the fiberglass-reinforced exposure-laminated used in printed circuit boards. It also functions as a graze to rate epoxy laminate sheets. The 4 in FR differentiates it from other materials in the same category.
The most essential layer of the material is fiberglass laced into a thin, cloth-like sheet. The fiberglass gives Fr4 its needed structural stability. The innermost fiberglass layer is then rounded up and bound by a flame-resistant epoxy resin. This resin is what makes the material different from other physical properties.

Different Levels of FR4 PCBs

Fr4 PCB is generally used to produce double-sided circuit boards and multiple-layer circuit boards. It is divided into the following levels.

1. Fr4 PCB Class A1 Copper Clad Laminate
   This grade is typically used in the military industry, computers, communications, industrial, automobile circuits, instruments, and other electronic products. The quality of these products has reached a world-class level, providing the highest grade and best performance.
2. Fr4 PCB A2 Copper Clad Laminate
   This grade is mainly used for regular computers, advanced household appliances, instruments, and general electronic products. These copper-clad laminates are commonly used and meet all performance requirements for general industrial electronics.
3.  Fr4 PCB A3 Copper Clad Laminate
   This grade of copper-clad laminate is an FR-4 product developed for home appliances, computer auxiliaries, and everyday electronics like toys, game consoles, and calculators. It is of a very low price providing a competitive advantage.
4. Fr4 PCB A4 Copper Clad Laminate
   This grade belongs to the low-end material of Fr4 PCB. However, it can still meet the needs of ordinary household appliances, general electronic products, and computers. The performance ratio is quite excellent and the price is the most competitive.
5. Fr4 PCB Class B Copper Clad Laminate
   This PCB grade has poor quality and stability, making it unsuitable for large circuit boards. It is best for products sized 100mm x 200mm. It is the cheapest option, so choose and use it carefully.