FR4 is a printed circuit board based upon glass-reinforced epoxy laminate material. It is one of the most utilized material due to the fact that it is low-cost in contrast with other materials and it can be utilized 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 various substrate density. It can be found thickness from 0.1 mm up to 3.2 mm. The required thickness will depend upon the application it will be used. Typical thinner densities 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. Since a large PCB is developed, greater densities are utilized when high effectiveness of the PCB is required.
With various copper layer thickness. Common copper thicknesses are 17, 35 or 70 um.
Different panel sizes can be bought, making use of one or another will depend on the devices the maker has and depending on the final size of the asked for PCBs. Typical panel sizes are 12x18 inches, 18x24 inches, and 21x29 inches. When you are designing a panel, you need to consider that not all the panel can be utilized to draw your PCBs. Around 2 inches length and 2 inches width will be used for other functions, like fiducial holes and other producer tasks and likewise avoid the panel can bend 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 example, Rogers laminates have normal values of 0.002 and alumina PCBs have worths of around 0.0002. The dielectric loss tangent shows the insertion losses of the material with the frequency. As can be seen, FR4 has higher worths and this is the reason it can be utilized only for low-frequency applications. Due to the fact that at high frequencies, the insertion losses of the lines are higher, in comparison with other, more expensive, choices.
Another important specification is the dielectric constant. The normal worth is around 4.6. This worth is slightly reliant on the maker and likewise the density of the substrate, but it is a value that usually supplies great outcomes when computations are performed from it. From this specification, the relation impedance/thickness of the line can be obtained. This is very useful when designing RF and digital circuits.
It is flame resistant.
It has hardly absolutely no water absorption
It has an extremely high dielectric breakdown, greater than 60KV. This suggests an extremely high voltage is required to change the properties of the material
It maintains its electrical and mechanical homes in various ecological conditions as dry or damp.
Common temperatures in which FR4 can work is from -55 to +125 ºC.
There are improved FR4 versions that provide other attributes such as lower dielectric worths or greater temperature level ranges. These boards are not standards and not all the vendors will offer 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 given that it is the most inexpensive Browse around this site material, with really excellent efficiency and since it is the material all the manufacturers have the possibility to use.
FR4 is a really excellent choice for digital applications, in which, FPGA, microcontrollers, ADCs, DCAs, buses, etc are utilized.
FR4 boards can be used for low-frequency applications. Approximately 1-2 GHz the residential or commercial properties of this material can be compared to other more costly alternatives like Rogers laminates or alumina. From MHz as much as 1 GHz the results will be slightly worse however the distinction in cost can help to decide for the FR4 alternative. From 2 GHz the distinctions are higher and generally other materials are selected. With FR4 and the matching parts, a broad catalog of RF circuits can be correctly created and made as amplifiers, switches, attenuators, etc.
The FR4 option on the PCB order page is the grade designation for the epoxy fiberglass that typically forms the PCB core and prepreg layers. In a common PCB, the core offers the rigidity 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, additional layers of FR4 prepreg are sandwiched between the inner core and the external copper layers. Common 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 utilized when high robustness of the PCB is required due to the fact that a big PCB is designed.