board and application areas

board and application areas


FR in FR4 stands for flame retardant, whereas the number 4 differentiates the material from other materials in this class. FR4 is a fiberglass-reinforced epoxy laminated sheet, which looks like a thin, and woven cloth sheet. The term FR4 also stands for the grade used to make these laminated sheets. The fiberglass construction provides structural stability to the material. The fiberglass layer is covered with an epoxy resin that is flame-resistant. This lends durability and strong mechanical properties to the material. All these properties make FR4 printed circuit boards popular among electronic contract manufacturers.


1. DC Board Applications: The vast majority of DC boards are completed with FR4 due to its low cost, excellent performance and accessibility.
2. Low-Frequency Applications: FR4 boards are commonly used in low-frequency applications due to their low cost and comparability to other materials. While FR4 is not ideal for high-frequency applications over 2 GHz, it is a good choice for lower-frequency applications that require functionality without excessive costs.
3. Digital Applications: FR4 is a very good option for many digital applications.

High-frequency PCBS

High-frequency PCBs refer to a general PCB design element, rather than a type of PCB construction like the previous models. High-frequency PCBs are circuit boards that are designed to transmit signals over one gigahertz.

High-frequency PCB materials often include FR4-grade glass-reinforced epoxy laminate, polyphenylene oxide (PPO) resin and Teflon. Teflon is one of the most expensive options available because of its small and stable dielectric constant, small amounts of dielectric loss and overall low water absorption.

Many aspects need to be considered when choosing high-frequency PCB board and its corresponding type of PCB connector, including dielectric constant (DK), dissipation, loss and dielectric thickness.

The most important of those is the Dk of the material in question. Materials with high probability for the change of dielectric constant often have changes in impedance, which can disrupt the harmonics that make up a digital signal and cause an overall loss of digital signal integrity — one of the things that high-frequency PCBs are designed to prevent.



1. Military and governmental communication systems
2. Aviation air-to-ground communications
3. Amateur radio
4. Shortwave international and regional broadcasting
5. Maritime sea-to-shore and ship-to-ship services
6. Over-the-horizon radar systems
7. Global Maritime Distress and Safety System (GMDSS) communication
8. Citizen's Band Radio services worldwide (generally 26-28 MHz, the higher portion of the HF band, that behaves more like low-VHF)


Polyimide (sometimes abbreviated PI) is a polymer of imide monomers. Polyimides have been in mass production since 1955. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, e.g. high temperature fuel cells, displays, and various military roles. A classic polyimide is Kapton, which is produced by condensation of pyromellitic dianhydride and 4,4'-oxydianiline.[1]



Insulation and passivation films

Mechanical parts

medical tubing



CEM-1 is low-cost, flame-retardant, cellulose-paper-based laminate with only one layer of woven glass fabric.