What is FR grade material

PCB boards are the foundation of any electrical equipment. What material is used for their manufacture will affect not only the final product, but also the price, reliability and durability.

Suitable materials for a PCB board?

The most common materials for the manufacture of solid PCBs include glass fabric laminate saturated with epoxy resin. Flexible base materials such as PET-polyethylene terephthalate, PEN-polyethylene naphthalate and PI-polyimides are used for the production of flexible PCBs.

FR is the material class designation for glass-reinforced epoxy laminate material. FR-4 material is a reinforced epoxy laminate and is made of epoxy and a fire-resistant fiberglass fabric. It is a self-extinguishing material due to the addition of bromine.

Class designations for glass epoxy laminates are G-10, G-11, FR-4, FR-5, and FR-6. Of these, FR-4 is the most widely used grade today. G-10, the predecessor of FR-4, lacks the flame retardancy of FR-4. Therefore, FR-4 has replaced G-10 in most cases and is ideal for the manufacture of solid PCBs. The lower versions are not fabric but paper.


FR-4 material

fiberglass epoxy is a popular and versatile high-pressure thermoset plastic laminate with a good strength-to-weight ratio. With almost zero water absorption, FR-4 is most commonly used as an electrical insulator with considerable mechanical strength. The material is known to retain its high mechanical values and electrical insulating properties in both dry and wet conditions. These attributes, along with good manufacturing properties, lend this grade utility for a wide range of electrical and mechanical applications.


Its glass transition temperature (TG) is in the order of 115 °C to 200 °C.  A standard FR-4 material for PCB fabrication will have a layer of FR-4 sandwiched between two thin layers of laminated copper.

FR-4 has the advantage of having a good resistance-to-weight ratio. It does not absorb water, maintains high mechanical strength and has good insulating ability in dry or wet environments.

Flame Retardant

Flame Retardant



Examples of FR-4

  • FR-4 standard: as the name suggests, this is a standard FR-4 with a heat resistance in the order of 140°C to 150°C.
  • High TG FR-4: this type of FR-4 has a higher glass transition (TG) of around 180°C.
  • High CTI FR-4: A comparative tracking index higher than 600 volts.
  • FR-4 without laminated copper: ideal for insulation boards and board supports.


Why choose FR-4?

The affordable cost of FR-4 makes the material a suitable choice for small batch or prototype PCB production. Its affordability helps consumers reduce the cost of PCB manufacturing. FR-4 is rightfully the most widely used material in PCB construction. Boards made from FR-4 are strong, waterproof and provide good insulation between the copper layers to minimize interference and promote good signal integrity.

However, FR-4 is not ideal for high frequency PCBs. Likewise, if you want to embed your circuit boards in products that do not easily accept components and which are poorly suited for flexible circuit boards, you should prefer a different material: polyimide/polyamide.

Introduction of VENTEC materials into production at Gatema PCB

VENTEC material is a high quality FR-4 material also suitable for high performance applications. It is primarily intended as an alternative for multilayer PCBs with higher Tg requirements.

As Gatema PCB Sales Manager Ondřej Horký explained: "VENTEC VT-47 material has slightly higher processing requirements, but it can be an alternative to the High Tg materials we use today because they have the same parameters. It is used in automotive, medical, industrial applications as well as in communication and computer technology."

VENTEC VT-47 is a basic material for the production of double and multilayer printed circuit boards and is also suitable for the production of RIGID FLEX boards. Due to the suitable rheological properties of the resin, it is also suitable for lead-free soldering.






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Ondřej Horký
Sales Manager