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Guide for fr4 circuit board

Guide for fr4 circuit board

The characteristics of FR4 or FR-4 make it very versatile and affordable. This is why it is widely used in printed circuit production. FR4 tg130 is the most commonly used material for fr4 circuit boards. FR4 describes a class of flame retardant glass fiber epoxy laminates.

fr4 circuit board
fr4 circuit board

Why FR4 in fr4 circuit board?

The reasonable price of FR4 makes it a standard choice for small batch PCB production or electronic prototype production.

However, FR4 is not ideal for high frequency printed circuits. Similarly, if you want to make a PCB into a product that is not easy to use components and hardly suitable for flexible PCBs, you should choose another material: polyimide / polyamide.

An example of FR4 in fr4 circuit board

  • Standard FR4: as the name suggests, this is the standard FR-4 with a heat resistance of about 140 ° C to 150 ° C.
  • High Tg FR4: This FR-4 has a high glass transition (TG) of about 180 ° C.
  • High CTI FR4: the comparison tracking index is higher than 600 v.
  • FR4 without copper laminate: ideal for insulation and plate support.
  • The characteristics of these different materials are described in detail later in this paper.

What is fr4 circuit board material?

We’ve all heard that the abbreviation FR4 will be thrown out when we buy a PCB wafer factory, but what does this actually mean? What is the effect of choosing PCB material? This article will help eliminate fog and introduce some popular materials for rigid pcb.

It is very likely that you have already considered FR4 a standard option for small batch or prototype PCBs, such as in seeed fusion. FR-4 is the code of refractory grade, which means that the resin material must be able to self extinguish after combustion. It is not a material name, but a material grade. For example, it has many subgroups of tgs-130.

The FR4 option on the PCB order page is the grade name of epoxy glass fiber, which usually forms the PCB core and prepreg layer. It is this fundamental characteristic that provides PCB with the electrical insulation and mechanical strength required to withstand increasingly demanding applications. In a typical PCB, the core provides rigidity and foundation on which PCB traces can be printed. In addition, the FR4 core and the laminate form an electrical insulation layer to separate the copper layer.

For double-layer boards, the FR4 core separates the top and bottom copper layers, while for Multilayer PCB, an additional FR4 prepreg layer is sandwiched between the inner core and the outer copper layer. The desired final PCB thickness can be controlled by mixing different laminate thicknesses. This arrangement is called stacking. For example, a typical 4-ply plate with a thickness of 1.6 mm can have a core of 1.2 mm. Two sheets of 0.12 mm prepreg covered with copper, solder mask and silk screen, accounting for about 1.6 mm. To build a 1.2 mm plate, replace the core with a 0.8 mm thick core.

The core is actually made up of a copper covered substrate, so it is also called a copper clad laminate. The specified core thickness usually does not include copper. To accommodate different final copper thicknesses (e.g., 1 oz, 2 oz, etc.), cores with different plating thicknesses (e.g., 1.5 oz copper weight) can be purchased. After plating, they will stack up to 2 ounces of plates.

Performance and materials of FR4 in fr4 circuit board

  • FR4 is a standard defined by NEMA for glass reinforced epoxy laminates.
  • Fr stands for “flame retardant”, indicating that the material meets the UL94V-0 standard for flammability of plastic materials. The 94V-0 code can be found on all FR-4 PCBs. It ensures that the flame does not burn and can be extinguished quickly when burning.
  • For high Tg or Hitg, the glass transition temperature (TG) is about 115 ° C to 200 ° C, depending on the manufacturing method and the resin used. A standard FR-4 PCB will have a FR-4 layer sandwiched between two thin copper layers.
  • The FR-4 uses bromine, a fire-resistant so-called halogen chemical element. In most applications, it replaces the G-10, another low corrosion resistant composite.
  • FR4 has the advantage of good resistance weight ratio. It does not absorb water, maintains high mechanical strength, and has good insulation ability in dry or humid environment.



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