FR4 is a printed circuit board based upon glass-reinforced epoxy laminate material. It is the a lot of utilized material because it is cheap in comparison with other materials and it can be used in numerous applications.
FR4 Types
You can find different FR4 boards:
Single layer boards, with only copper in the top of the substrate or double layer, with two copper layers, one on each side.
With different substrate density. It can be discovered density from 0.1 mm approximately 3.2 mm. The needed density will depend upon the application it will be utilized. 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 required.
With different copper layer thickness. Typical copper thicknesses are 17, 35 or 70 um.
Different panel sizes can be bought, the usage of one or another will depend upon the equipment the maker has and depending on the final size of the asked for PCBs. Normal panel sizes are 12x18 inches, 18x24 inches, and 21x29 inches. When you are developing a panel, you need to think about that not all the panel can be used to draw your PCBs. Around 2 inches length and 2 inches width will be used for other functions, like fiducial holes and other manufacturer jobs and likewise avoid the panel can bend if work is carried out close to the borders.
FR4 Properties
It has a dielectric loss tangent of around 0.017 to 0.025 while, for instance, Rogers laminates have typical values of 0.002 and alumina PCBs have worths of around 0.0002. The dielectric loss tangent indicates the insertion losses of the material with the frequency. As can be seen, FR4 has greater worths and this is the reason it can be used just for low-frequency applications. Since at high frequencies, the insertion losses of the lines are higher, in comparison with other, more costly, choices.
Another essential specification is the dielectric constant. The typical value is around 4.6. This value is somewhat depending on the producer and likewise the density of the substrate, but it is a value that typically offers excellent results when estimations are carried out from it. From this parameter, the relation impedance/thickness of the line can be acquired. When creating RF and digital circuits, this is very useful.
It is flame resistant.
It has hardly absolutely no water absorption
It has a very high dielectric breakdown, higher than 60KV. This suggests a really high voltage is needed to alter the properties of the material
It preserves its mechanical and electrical homes in different environmental conditions as dry or damp.
Normal temperatures in which FR4 can work is from -55 to +125 ºC.
There are better FR4 variations that supply other qualities such as lower dielectric worths or higher temperature ranges. These boards are not requirements and not all the suppliers will provide them.
FR4 Uses
FR4 is utilized around the world for various applications, commercial, civil, automotive or even military applications.
It is utilized for DC, low-frequency and digital RF applications.
Almost the total of DC boards are done with FR4 since it is the least expensive material, with great efficiency and due to the fact that it is the material all the manufacturers have the possibility to use.
FR4 is a great alternative for digital applications, in which, FPGA, microcontrollers, ADCs, DCAs, buses, etc are used.
FR4 boards can be used for low-frequency applications. Up to 1-2 GHz the residential or commercial properties of this material can be compared to other more expensive choices Browse around this site like Rogers laminates or alumina. From MHz as much as 1 GHz the outcomes will be slightly worse however the distinction in cost can help to decide for the FR4 option. From 2 GHz the differences are higher and typically other materials are selected. With FR4 and the corresponding components, a large catalog of RF circuits can be correctly designed and fabricated as amplifiers, switches, attenuators, and so on.
The FR4 alternative on the PCB order page is the grade designation for the epoxy fiberglass that often forms the PCB core and prepreg layers. In a typical PCB, the core provides the rigidity and the foundation on which the PCB traces can be 'printed' onto. For double layer boards, an FR4 core separates the bottom and top copper layers whereas, in multilayer PCBs, additional layers of FR4 prepreg are sandwiched in between the external copper and the inner core layers. Typical thinner thicknesses are utilized in multilayer boards in which the FR4 board is utilized to distribute signals to other boards, in order to not increase the thickness of the PCB. Greater densities are used when high toughness of the PCB is needed since a large PCB is developed.