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Trang Chủ/ 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 Bảng mạch 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 Bảng mạch 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.

Trong các ti vi ống của những năm 1960, bìa cứng được thay thế bằng loại chịu nhiệt độ. Nhưng Bakelite rất giòn. Nhưng các thành phần có độ nhạy cao ngày nay cần một vật liệu để sản xuất Bảng mạch Fr4.

Nó vẫn bền và đáng tin cậy trong các thông số thiết lập. Tấm FR4 là lý tưởng cho việc này. Nó có độ bền lên đến 100 ° C và không phân tách. Tấm cung cấp độ bền đứt tuyệt vời và có thể chịu tải cơ học và tĩnh tốt.


Tuy nhiên, ưu điểm quan trọng nhất của chúng là khả năng chống dòng điện rò rỉ và cách điện. Các tính chất đặc biệt của Bảng mạch Fr4  làm cho vật liệu đặc biệt thích hợp để khắc bảng mạch.

Mạch in là gì?

Mạch in là một tập hợp các rãnh đồng được thể hiện trên một giá đỡ cách điện.

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. Bảng mạch Fr4

Bảng mạch 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 Bảng mạch Fr4. Such as:

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

In the case of Bảng mạch 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).


Bảng mạch Fr4 looked into the core

The designation “FR” means “Flame Retandant” – that is, flame retardant. In practical terms, this means that no fire can establish itself on a circuit board made of this material. The number indicates a resistance class.


Essentially, a FR4 printed circuit is a GRP composite material. It consists of a multi-layer mat made of glass roving fabric impregnated with epoxy resin.

In the course of its special use as a mounting plate for electronic assemblies, great importance is attached. It is to complete saturation of the fabric mats in the manufacture of the FR4 plate.

Usually a vacuum pressing process is used for this. It also allows the resin to flow around the last fiber.

Fr4 Circuit Board suppliers

Advantages of Fr4 Circuit Board

Các Bảng mạch Fr4 has proven its worth especially for use as a board base for two reasons:

  • Heat resistance
  • Short-circuit strength

The FR4 board is by no means non-flammable. But it offers a thermal fatigue strength of up to 100 ° Celsius. The maximum operating temperature can even reach up to 140 °.

However, for reasons of safety, manufacturers usually give a value below 100 ° C. If the thermal load is above the specified limit, the Fr4 Circuit panel does not catch fire immediately.

However, if the GRP material begins to delaminate, the electronic components no longer adhere to the base material. Therefore, the short-circuit resistance suffers.

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 Bảng mạch Fr4.

Bảng mạch 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 Bảng mạch 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 Bảng mạch 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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