Fiberglass is a laminated pressed composite material. It is made of two or more parallel layers, impregnated with a polymer (thermosetting) resin. It is easily stamped/machined. Depending on the purpose, the basic material can be either structural or electrotechnical.

— Safe, environmentally friendly material.
— High mechanical/dielectric values.
— Excellent resistance to aggressive chemical media, moisture, and temperature fluctuations.
— Durable: average service life - 20 years.

It is used to produce both double-layer and MPB of high strength in the following areas:
— Metal industry
— Shipbuilding
— Electrical and radio engineering
— Aviation equipment and components for missiles

— Standard — FR-4
The vitrification temperature is 130 °C. There is UV protection — UV blocking. It is the most common type of fiberglass, low-cost.

— With high temperature values of vitrification
The vitrification temperature varies from 170˚ to 200˚. Unlike standard FR-4, high-temperature dielectric substrates have via holes of higher quality (by 1.8%) and more tolerance on thickness (by 3%). The total quantity of resin spots is reduced by 12%, compared to standard materials. They are easy-processing and resistant to chemical reagents.

— Halogen-free
Basic halogen-free materials are compatible with lead-free tinning and soldering. Flammability class: UL94-V0.

The standard fiberglass of FR-4 specification is 1.6 mm thick, and it contains 8 prepreg layers. The fourth (central) layer has the manufacturer’s logo, and its color indicates the assignment of a flammability class. For example, blue color indicates the flammability class UL94-HB (the mounting substrate is not fireproof), red — UL94-V0 (fireproof material).

The real color of FR-4 is transparent, green tint appears on the printed circuit board only after the application of the soldermask.

Specific volume resistance, MΩ / cm

1,9∙10^8

10^7−5∙10^7

10^15−5∙10^15

Specific surface resistance, MΩ

3,8∙10^7

10^8−5∙10^8

10^14−5∙10^14

Index of the dielectric constant

4,8

5,2

4,7

Dispersion coefficient

0,018

0,01

0,015

Index of thermal resistance at soldering 288 °C, sec

Not more than 20

Less than 120

Peel resistance coefficient, kN/m

1,43−1,81

1,86

1,96

Dielectric breakdown, HF

Not more than 50

Bending strength, N mm2

490

Insulation resistance

10^7−10^8

10^13-10^14

Vitrifaction temperature, °C

130

170−200