What is FR-4 PCB material?
We've all heard the abbreviation FR4 being tossed about eventually when looking for a PCB fab house, however what does it actually indicate? And what ramifications does it have when choosing a PCB material? This post will help clear the fog and present some popular materials available for rigid PCBs.
Most most likely, you will have seen FR4 as the basic option for small batch or model PCBs like in Speed Fusion. FR-4 describes a grade of material rather than a material itself and has numerous sub gradings and types such as TG130, High TG, FR4-Rogers. The FR4 alternative on the PCB order page is the grade classification for the epoxy fiberglass that typically forms the PCB core and prepreg layers. It is the properties of this base that provides the PCB the electrical seclusion and mechanical strength required to withstand progressively requiring applications.
In a typical PCB, the core offers the rigidness and the structure on which the PCB traces can be 'printed' onto. In addition, the FR4 core and laminates form the electrical isolation separating copper layers. For double layer boards, an FR4 core separates the top and bottom copper layers whereas, in multilayer PCBs, extra layers of FR4 prepreg are sandwiched in between the inner core and the outer copper layers. The preferred last thickness of the PCB can be controlled by adding or getting rid of specific laminates or using laminates of different densities. For instance, normally, a 1.6 mm board will have 8 layers of fiberglass sheets, if we wanted a 0.8 mm board we can decrease the number of sheets to 4.
The name FR4 comes from the NEMU grading system where the 'FR' stands for 'fire retardant', compliant with the UL94V-0 requirement. You might have seen that on the Speed Fusion order page the FR4 option is followed by TG130. The TG refers to the shift glass temperature level-- the temperature level at which the glass-reinforced material will start to deform and soften. For Fusion's basic boards this worth is 130 ° C, which is ample for most applications. Special High TG materials can stand up to temperature levels of 170-- 180 ° C and can be bought online utilizing the Advanced PCB service.
FR4 laminates owe their flame resistance due to its bromine content, a non-reactive halogen commonly used in market for its flame slowing down homes. This gives FR4 materials obvious advantages as a stock PCB material, particularly in prototyping where circuits are still in the preliminary screening phases and may be pushed to extremes. If your soldering skills are not up to standard, it is also a little guaranteeing.
Other comparable grades utilized for PCBs consist of FR2, which is a type of fire retarding fiberglass resin bonded paper and G10 which is not flame resistant at all. FR2 is less expensive and so has its usages in mass production of low-end electrical devices. G10, a predecessor to FR4, has actually all however been taken control of by the safer FR4 standard. Its only use in PCBs now is in designs that prefer this combustible home.
This blog site has covered more information on rigid PCB materials than the average hobbyist will ever need, however must you ever discover the usage for High TG or more customized materials, you can take a look at Speed Fusion Advanced PCB service for more options including FR4 Material high-frequency boards and rigid-flex PCBs.
The FR4 option on the PCB order page is the grade classification for the epoxy fiberglass that typically forms the PCB core and prepreg layers. In a common PCB, the core provides 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 in between the outer 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 robustness of the PCB is needed since a large PCB is designed.