The commonly used substrates for PCBs : FR4

What is FR4 ?

FR-4, one of the commonly used substrates for PCBs, is a code name for a flame-resistant material grade, which means that the resin material must be able to self-extinguish after the combustion state of a material specification.FR-4, also written as FR4, is both a name and a standard grade. The organic substrate material used to manufacture PCBs consists of three components: resin, reinforcement material, and conductive copper foil.Fr4 G10 washer spacer glasket

FR-4 sheet general technical indicators are: bending strength, peel strength, thermal shock properties, flame retardant properties, volume resistance coefficient, surface resistance, dielectric constant, dielectric loss angle tangent, glass transition temperature Tg, dimensional stability, the maximum operating temperature, warpage and so on.G10 FR4 glass epoxy laminate

PCB material classification

1.Glass cloth substrate: FR-4, FR-5

By the special electronic cloth impregnated with epoxy phenolic epoxy resin after high temperature, high pressure, hot press and become a plate-like compression products.

Epoxy glass fiber cloth substrate (commonly known as: epoxy board, fiberglass board, fiberboard, FR4). Epoxy glass fiber not substrate is a class of substrate with epoxy resin as binder and electronic grade glass fiber cloth as reinforcing material.G10 FR4 glass epoxy laminate

Epoxy glass fiber cloth copper cladding board has high strength, good heat resistance, good dielectric properties, the substrate through-hole can be metalized to achieve double-sided multi-layer printing layer and layer circuit conduction, epoxy glass fiber cloth copper cladding board is the most widely used in all the qualities of the copper cladding board, the largest amount of a class.

2.Paper substrate: FR-1,FR-2, FR-3, etc.

Phenolic paper substrate is a phenolic resin as the binder, with wood pulp fiber cloth as the surface reinforcement material.FR4,G10

3.Composite substrate: CEM-1 and CEM-3

This type of substrate is mainly CEM series copper-clad plate, of which CEM-1 (epoxy paper-based core material) and CEM-3 (epoxy glass nonwoven core material) are two important varieties of CEM. CEM series plate has good processability, flatness, dimensional stability, thickness accuracy, its mechanical strength, dielectric properties of the water absorption, resistance to metal migration and so on is higher than the paper substrate, while the mechanical strength (CEM (-3) is about 80% of FR-4, the price is lower than FR-4 board.

4.Special material substrate (ceramic, metal, etc.)

FR in NEMA classification standard means Flame-Retardant or Fire-Resistant, i.e. Fire-Resistant grade, so FR grade panels are Flame-Retardant panels, and the number "4" is to distinguish this material from other materials of the same grade, 4 The number "4" distinguishes the material from other materials of the same grade, with 4 indicating that the resin is epoxy resin, the reinforcing material is fiberglass cloth, and the flame-retardant grade is UL94 V-0. FR-1, FR-2, and FR-3 are UL 94V-1 with different resins and reinforcement materials.

FR-4 is only one of the grades in the NEMA Substrate Grade Classification and represents the material class, not the specific material. A common problem is that FR-4 is often confused with a specific dielectric, such as the FR-4 material in our simulation software, which has a default dielectric constant of 4.2 and a loss angle tangent of 0.02, but many low to medium loss sheets are also FR-4 rated.

FR-4 epoxy glass cloth laminate surface colors are:

Yellow FR-4, White FR-4, Black FR-4, Blue FR-4 and so on.

Characteristics: high mechanical and dielectric properties, good heat and moisture resistance and good machinability.

Uses: Electric motors, electrical equipment for insulation structure parts, including various types of switches FPC reinforcement Electrical insulation carbon film printed circuit boards, computer drilling pads mold fixtures, etc. (PCB test frame) and can be used in humid environmental conditions and transformer oil.

Basic Characteristics

Vertical laminar bending strength A: Normal: E-1/150, 150±5℃≥340Mpa

Parallel laminar impact strength (simple beam method): ≥230KJ/m

Insulation resistance after immersion in water (D-24/23): ≥5.0×108Ω

Vertical laminar electrical strength (in 90±2℃ transformer oil, plate thickness 1mm): ≥14.2MV/m

Parallel layer to the breakdown voltage (in 90 ± 2 ℃ transformer oil): ≥ 40KV

Relative dielectric constant (50Hz): ≤5.5

Relative dielectric constant (1MHz): ≤5.5

Dielectric loss factor (50Hz): ≤0.04

Dielectric loss factor (1MHz): ≤0.04

Water absorption (D-24/23, plate thickness 1.6mm): ≤19mg

Density: 1.70-1.90g/cm³

Flammability: FV0

Process characteristics

(1)FR-4 process platen melting point (203℃)

(2)High chemical resistance

(3)Low loss factor (Df 0.0025)

(4)Stable and low dielectric constant (Dk 2.35)

(5) Thermoplastic material

Features

FR-4 epoxy glass fiber cloth substrate, is a class of substrate with epoxy resin as binder and electronic grade glass fiber cloth as reinforcement. Its bonding sheet and inner core thin copper-clad laminate are important substrates for making multilayer printed circuit boards.

Performance

Epoxy glass fiber cloth substrate mechanical properties, dimensional stability, impact resistance, moisture resistance is higher than the paper substrate. It has excellent electrical properties, higher working temperature, and its own performance is less affected by the environment. In the processing technology, than other resin glass fiber cloth substrate has great superiority. These products are mainly used for double-sided PCB, with a large amount.

Applications

Epoxy fiberglass cloth substrate, the most widely used product type FR-4, due to the electronic product installation technology and PCB technology development needs, and the emergence of high Tg FR-4 products.