Casa/ Blog/ What is Fr4 Circuit Board: Latest step by step Guide 2020

What is Fr4 Circuit Board: Latest step by step Guide 2020


An ultimate beginners fr4 printed circuit board cost and advantages

Fr4 Circuit Board manufacturers

Fr4 Circuit Board Introduction

The manufacture of electronic assemblies has long ceased to be the domain of placa de circuito Fr4. The tools, components and materials available today have become better and cheaper for private users. so that the professional production of circuit boards has now become a hobby for many.

Planning, manufacturing and trying out electronic circuits is part of the large area of ​​do-it-yourself. It not only includes seasoned men. School children are also becoming more and more enthusiastic about the world of:

  • Diodes
  • transistors and

In order for the self-soldered placa de circuito Fr4 to remain safe and operational for a long time, a suitable base material is crucial. Here, FR4 has developed into a new standard in recent years. We introduce the most popular material for printed circuit boards

What an FR4 circuit board has to do?

You can still find it in old radios: the cardboard circuit board. In the technical language “FR-2 hard paper” was said to be. However, it is what it is: Pressed pulp.

In the tube televisions of the 1960s, the cardboard was replaced by temperature-resistant. But very brittle Bakelite. But today’s highly sensitive components need a material for the production of placa de circuito Fr4.

It remains durable and reliable within the set parameters. The FR4 plate is ideally suited for this. It is durable up to 100 ° C and does not delaminate. The plate offers excellent breaking strength and can withstand good mechanical and static loads.


Their most important advantage, however, is their resistance to leakage current and insulation. The special properties of placa de circuito Fr4 make the material particularly suitable for etching circuit boards.

What is printed circuit?

A printed circuit is a set of copper tracks represented on an insulating support.

These tracks are used to connect the various components that make up the electronic circuit.

The insulating support can be made with two different materials:

  1. Bakelitewhich is a yellow / brown phenolic resin, used a lot in the past.
  2. placa de circuito Fr4

placa de circuito Fr4 has better electrical characteristics than Bakelite. But it is more expensive and spoils the bits more quickly when drilling.

Material for the circuit board

In the past, Pertinax was often used as the base material. Nowadays it is only used for cheap, mass-produced items. Glass fiber mats soaked in epoxy resin called FR4 have better tracking resistance and better high-frequency properties as well as lower water absorption than hard paper.


Material designations for the circuit board:


  • FR1 = phenolic resin + paper (cheap type)
  • FR2 = phenolic resin + paper (standard quality)
  • FR3 = epoxy resin + paper
  • FR4 = epoxy resin + fiberglass fabric
  • FR5 = epoxy resin + fiberglass fabric (heat-resistant)


FR stands for flame retardant


For special applications, other materials are used in placa de circuito Fr4. Such as:

  • Aluminio
  • Teflon
  • or ceramic and polyester films for flexible printed circuit boards.

En el caso de placa de circuito Fr4 with high demands on heat dissipation, base materials with electrically insulated metal cores are used. For instance, in the field of lighting technology with high-performance light emitting diodes. This material is also called Direct Bonded Copper, or Insulated metal substrate (IMS).


placa de circuito Fr4 looked into the core

La designación “FR” significa “Retardante de llama”, es decir, retardante de llama. En términos prácticos, esto significa que ningún fuego puede establecerse en una placa de circuito hecha de este material. El número indica una clase de resistencia.


Básicamente, un circuito impreso FR4  es un material compuesto de GRP. Consiste en una esterilla multicapa de tejido de fibra de vidrio impregnado con resina epoxi.

En el curso de su uso especial como placa de montaje para ensamblajes electrónicos, se le da gran importancia. Se trata de completar la saturación de las esteras de tela en la fabricación de la placa FR4.

Por lo general, se utiliza un proceso de prensado al vacío para esto. También permite que la resina fluya alrededor de la última fibra.

Fr4 Circuit Board suppliers

Ventajas de la placa de circuito Fr4

La placa de circuito Fr4  ha demostrado su valor especialmente para su uso como base de placa por dos razones:

  • Resistencia al calor
  • Fuerza de cortocircuito

La placa FR4 no es de ninguna manera inflamable. Pero ofrece una resistencia a la fatiga térmica de hasta 100 ° Celsius. La temperatura máxima de funcionamiento puede alcanzar incluso los 140 °.

Sin embargo, por razones de seguridad, los fabricantes suelen dar un valor por debajo de 100 ° C. Si la carga térmica está por encima del límite especificado, el circuito Fr4 no se incendia inmediatamente.

Sin embargo, si el material GRP comienza a deslaminarse, los componentes electrónicos ya no se adhieren al material base. Por tanto, la resistencia al cortocircuito sufre.

The dielectric strength of a normal FR-4 plate is approx. 20 kV / mm. That in itself is a very astonishing value. because, as the unit says, it applies per millimeter.

The inexpensive and technically very resilient panels are therefore available from very low thicknesses. Even wafer-thin panels, for example 0.2 mm thick, can withstand 4 kV.

The commercially available formats range up to 20 millimeters thick. Here you are already in the range of 400 kV. Although the boards are only two centimeters thick, hobbyists have to work very hard to get into the limit areas when manufacturing placa de circuito Fr4.

placa de circuito Fr4 is Inexpensive, also in industrial quality

What is also not entirely irrelevant for hobby and semi-professional electronic manufacturer. As an example: a plate with a thickness of 1mm, a width of 100mm and a height of 300mm is available at very low cost.

The panels are therefore absolutely inexpensive overall. The semi-finished placa de circuito Fr4 are offered in the standard dimensions of 500 millimeters wide and 300 millimeters long. Since printed circuit board production usually requires much smaller formats, boards of this size last a long time.

For experiment circuits in the range up to 24 volts, plates with low thicknesses are sufficient. They are ideal for student experiments and beginner circuits. A thin plate also means that a lot of weight is saved.

With thicker boards, the production of a placa de circuito Fr4 can be approached much more courageously and progressively. The strongest GRP panel made of FR4 is 20 millimeters thick, but 14mm panel thickness is common for many applications.

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