FR4 is a printed circuit board based on glass-reinforced epoxy laminate material. Since it is inexpensive in contrast with other materials and it can be utilized in lots of applications, it is the a lot of utilized material.
FR4 Types
You can discover various 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 thickness. It can be found thickness from 0.1 mm as much as 3.2 mm. The required thickness will depend on 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. Higher thicknesses are used when high toughness of the PCB is required since a big PCB is created.
With various copper layer density. Normal copper thicknesses are 17, 35 or 70 um.
Different panel sizes can be bought, the use of one or another will depend on the equipment the manufacturer has and depending on the final size of the requested PCBs. Typical panel sizes are 12x18 inches, 18x24 inches, and 21x29 inches. You have to consider that not all the panel can be utilized to draw your PCBs when you are creating a panel. 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 the borders.
FR4 Properties
It has a dielectric loss tangent of around 0.017 to 0.025 while, for instance, Rogers laminates have normal worths of 0.002 and alumina PCBs have worths of around 0.0002. The dielectric loss tangent suggests 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 only for low-frequency applications. Because at high frequencies, the insertion Check out here losses of the lines are higher, in comparison with other, more expensive, options.
Another important parameter is the dielectric constant. The typical worth is around 4.6. This worth is a little depending on the maker and likewise the density of the substrate, however it is a value that generally offers good results when calculations are performed from it. From this parameter, the relation impedance/thickness of the line can be obtained. When creating RF and digital circuits, this is very helpful.
It is flame resistant.
It has hardly zero water absorption
It has an extremely high dielectric breakdown, greater than 60KV. This implies a very high voltage is required to change the homes of the material
It keeps its mechanical and electrical homes in various environmental conditions as dry or wet.
Typical temperatures in which FR4 can work is from -55 to +125 ºC.
There are improved FR4 versions that supply other attributes such as lower dielectric worths or greater temperature ranges. These boards are not standards and not all the vendors 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.
Almost the overall of DC boards are finished with FR4 because it is the most affordable material, with very good efficiency and due to the fact that it is the material all the producers have the possibility to utilize.
FR4 is an extremely good 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 expensive alternatives like Rogers laminates or alumina. From MHz approximately 1 GHz the results will be slightly worse however the distinction in cost can help to choose 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, and so on.
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 foundation on which the PCB traces can be 'printed' onto. For double layer boards, an FR4 core separates the bottom and leading copper layers whereas, in multilayer PCBs, additional layers of FR4 prepreg are sandwiched between the external copper and the inner core layers. Common thinner thicknesses are utilized in multilayer boards in which the FR4 board is used to disperse signals to other boards, in order to not increase the density of the PCB. Higher thicknesses are utilized when high effectiveness of the PCB is needed because a large PCB is created.