What is FR4?
FR4 is a standard rating and name applied to fiberglass-reinforced epoxy-laminated sheets used in printed circuit board manufacturing. The FR4 rating serves as a grade to indicate the base quality of a laminate sheet, with a variety of materials and designs falling under this category.
The term “FR” represents the material’s flame retardant properties, while the number “4” differentiates it from other materials in the same class.
FR4 is a composite structure consisting of a fiberglass layer at its core. This provides structural stability and a flame-resistant epoxy resin surrounding and binding the fiberglass layer. This resin gives FR4 its rigidity and other physical properties. FR4 sheets are a popular choice among electrical engineers and designers due to their low cost and versatility, high dielectric strength, strength-to-weight ratio, resistance to moisture, and relative temperature resistance, allowing them to perform well in various environmental conditions.
Applications of FR4
PCBs: FR4 sheets are widely popular among electrical engineers and designers as a PCB base material due to its low cost, versatility, and beneficial physical properties, such as high dielectric strength, strength-to-weight ratio, resistance to moisture, and relative temperature resistance.
Insulators: FR4 is used as an insulator for electrical and electronic applications, including transformers, motors, generators, and electronic equipment.
Structural components: FR4 laminates are used in the manufacturing of structural components such as beams, panels, and frames for aircraft, automotive, and marine applications.
Consumer electronics: FR4 is used in the manufacturing of consumer electronics such as smartphones, laptops, tablets, and gaming consoles.
Industrial equipment: FR4 is used in the manufacturing of industrial equipment such as control panels, switches, relays, and sensors.
Aerospace: FR4 is used in the manufacturing of parts and components for aerospace applications such as satellites, rockets, and aircraft.
G10 and FR4
FR4 and its predecessor G10 differ in their resin composition. FR4 has a slight chemical modification that makes the resulting laminate more flame retardant, while all other properties such as durability, low moisture absorption, electrical insulation, and adhesive properties remain virtually identical. This innovation allows FR4 to be used as a replacement for G10 in almost every application. Here are some of the advantages of using FR4:
Flame Resistance: The term “FR” in FR4 stands for “flame retardant,” meaning that the material has the ability to resist combustion and slow down the spread of flames.
Durability: FR4 is a strong and durable material that can withstand mechanical stress and impact. It is also resistant to moisture and humidity, making it ideal for use in harsh environments.
Electrical Properties: FR4 has high dielectric strength and low dissipation factor, which makes it an excellent electrical insulator. It is commonly used in printed circuit board (PCB) manufacturing as a base material.
Thermal Resistance: FR4 has good thermal resistance properties, which allows it to perform well in high-temperature applications.
Cost-Effective: FR4 is a cost-effective material that is widely available and easy to manufacture, making it a popular choice in various industries.
The combination of flame resistance, durability, electrical properties, thermal resistance, and cost-effectiveness makes FR4 a versatile and reliable material for various applications, especially in electronics and electrical engineering.
Single or double-sided PCB structures typically consist of an FR4 core with copper layers on both top and bottom. Multilayer boards have additional prepreg layers between the center core and top/bottom copper layers. The core is a substrate with a copper covering, known as a copper clad laminate, which may be made of FR4 along with the laminate and prepreg layers.
The properties of FR4 may vary slightly depending on the manufacturer, but generally, it has favorable strength and water resistance attributes that make it a popular choice for use as an insulator in various electrical applications. Its purpose in PCBs is to isolate adjacent copper planes and provide overall bending and flexural strength for the structure.
Jaco offers CNC machining services for both G10 and FR4 sheets with a tolerance of up to +-.005. G10 drilling, milling, and machining services are available to cut to size or machine to CAD drawings. Machining G10 can present challenges due to highly abrasive glass fillers, which can result in delamination if metal machining speeds are used. However, Jaco specializes in plastic machining and has equipment, from machine tools to dust collection, specifically designed for machining composites, laminates, and glass-filled resins.