FR4 is a printed circuit board based upon glass-reinforced epoxy laminate material. It is the a lot of utilized material due to the fact that it is cheap in comparison with other materials and it can be used in many applications.
FR4 Types
You can discover various FR4 boards:
Single layer boards, with just copper in the top of the substrate or double layer, with 2 copper layers, one on each side.
With various substrate density. It can be found density from 0.1 mm up to 3.2 mm. The required thickness will depend on the application it will be used. Typical thinner thicknesses are used in multilayer boards in which the FR4 board is used to distribute signals to other boards, in order to not increase the thickness of the PCB. Due to the fact that a big PCB is created, greater densities are utilized when high effectiveness of the PCB is needed.
With various copper layer density. Normal copper densities are 17, 35 or 70 um.
Various panel sizes can be purchased, using one or another will depend upon the devices the maker has and depending upon the last size of the asked for PCBs. Normal panel sizes are 12x18 inches, 18x24 inches, and 21x29 inches. When you are creating a panel, you need to think about that not all the panel can be utilized to draw your PCBs. Around 2 inches length and 2 inches width will be utilized for other functions, like fiducial holes and other maker jobs and likewise prevent the panel can flex if work is carried out near to the borders.
FR4 Properties
It has a dielectric loss tangent of around 0.017 to 0.025 while, for instance, Rogers laminates have common worths of 0.002 and alumina PCBs have values of around 0.0002. The dielectric loss tangent suggests the insertion losses of the material with the frequency. As can be seen, FR4 has higher values and this is the reason it can be used only for low-frequency applications. Because at high frequencies, the insertion losses of the lines are higher, in comparison with other, more expensive, options.
Another important criterion is the dielectric constant. The normal value is around 4.6. This value is a little dependent on the producer and likewise the thickness of the substrate, but it is a value that normally supplies good outcomes when computations are carried out from it. From this parameter, the relation impedance/thickness of the line can be obtained. When developing RF and digital circuits, this is really useful.
It is flame resistant.
It has barely no water absorption
It has an extremely high dielectric breakdown, greater than 60KV. This implies a very high voltage is required to alter the homes of the material
It maintains its electrical and mechanical residential or commercial properties in different environmental conditions as dry or wet.
Common temperature levels in which FR4 can work is from -55 to +125 ºC.
There are better FR4 versions that offer other qualities such as lower dielectric worths or greater temperature ranges. These boards are not standards and not all the suppliers will use them.
FR4 Uses
FR4 is utilized around the world for various applications, industrial, civil, automobile or even military applications.
It is used for DC, low-frequency and digital RF applications.
Virtually the total of DC boards are finished with FR4 considering that it is the most inexpensive material, with great performance and because it is the material all the producers have the possibility to use.
FR4 is an excellent option for digital applications, in which, FPGA, microcontrollers, ADCs, DCAs, buses, etc are utilized.
FR4 boards can be utilized for low-frequency applications. As much as 1-2 GHz the residential or commercial properties of this material can be compared with other more Additional info expensive alternatives like Rogers laminates or alumina. From MHz approximately 1 GHz the outcomes will be somewhat worse however the distinction in cost can assist to decide for the FR4 option. From 2 GHz the distinctions are greater and usually other materials are chosen. With FR4 and the corresponding components, a large brochure of RF circuits can be properly designed and fabricated as amplifiers, switches, attenuators, and so on.
The FR4 alternative on the PCB order page is the grade classification for the epoxy fiberglass that often forms the PCB core and prepreg layers. In a typical PCB, the core supplies the rigidness and the structure on which the PCB traces can be 'printed' onto. For double layer boards, an FR4 core separates the leading and bottom copper layers whereas, in multilayer PCBs, extra layers of FR4 prepreg are sandwiched in between the inner core and the external copper layers. Normal thinner densities are utilized in multilayer boards in which the FR4 board is utilized to disperse signals to other boards, in order to not increase the density of the PCB. Greater thicknesses are used when high robustness of the PCB is required because a large PCB is designed.