The facts of FR4 PCB that you never knew

The facts of FR4 PCB that you never knew

Table of Contents

Fr4 is a code for the grade of fire-resistant materials, which means that the resin material must be able to self-extinguish a material specification after burning. It is not a material name, but a material grade. Therefore, there are many kinds of FR-4 grade materials used in general circuit boards. However, most of them are composite materials made from epoxy resin with so-called tera-function Filler and glass fiber.

National Electrical Manufacturers Association known as (NEMA) was established in 1926.The National Electrical Manufacturers Association (NEMA) is the largest organisation in the United States,which forms the standards for the manufacturing of medical imaging equipment and electrical equipment. 

What does FR4 stand for in PCB ?

PCB means (printed circuit board). It’s used in electronic industries and the flame retardant known as (FR4) works as an insulator for PCB manufacturing and production. And the number “4” indicates the woven glasses. FR4 is commonly known for its mechanical strength and resistance to water.

What material is FR4 made of ?

Flame retardant (FR4) is made from flame retardant epoxy resin and glass fabric composite material. It’s usually seen on a circuit board in the form of green colour. FR4 (flame retardant)has a very low coefficient of thermal expansion that indicates it doesn’t absorb moisture.


The usage of FR4

FR4 is one of the most useful materials in the production and manufacture of PCBs (printed circuit boards). It’s fibreglass-reinforced epoxy that is used to laminate sheets complying with the UL94 V-O standard. The most common use of FR4 is that it’s used as an insulator because it has high mechanical strength which I have already told you about above. This material is used to retain high mechanical values.

The role of FR4 in PCBs ?

This is the most common question about FR4 and the answer is that I already mentioned that it works as an insulator for PCB. Its role is to provide good insulation between the copper layer in the printed circuit board.

Why FR4 is used in most PCBs

FR4 PCB has a lot of qualities like it doesn’t absorb moisture, it protects PCBs from moisture, and it is a low-cost material so many people can easily afford this. It’s also the strongest plastic and the most important quality is its good capacity for insulation . These are some points I share with you that are the reason why most PCBs are used and recommend FR4 material.

FR4 material

Classification of common PCB FR4

FR4 (flame retardant) are classified by size or thickness and source of FR4 material. Size of thickness means the different thickness sizes of PCB FR4 throughout the standard thickness which is 0.78mm and double and triple is 1.57mm and 2.36mm. However, the source of FR4 material means the type of FR4 PCB material which is based on the source of FR4 material. these 2 things make it classified.

The advantage of FR4 used in PCBs

Here are some advantages of FR4 PCB.

  • FR4 is a low-cost and affordable material.
  • It has high mechanical strength.
  • The equipment has a big strength-to-weight proportion and is unheavy.
  • It does not absorb moisture.
  • The material has excellent electric loss characteristics.
  • FR4 doesn’t consume water, which makes it modified for numerous marine PCB functions, too.
  • The material is yellow to light green, which suberbly goes with any application.

What are the general technical indicators of PCB FR-4 ?

If we talk about the general technical indicator of PCB FR4. So I don’t exactly answer this question because it depends on what your requirements are, what you are looking for, and which type of material you want.

 That’s why I don’t exactly tell you the answer to this question but I want to say that if something meets your requirements your brain will automatically tell you to select it. Such as Standard FR4, as its name shows, is the standard FR-4 with heat resistance of the order of 140°C to 150°C. Its name indicates its function so if you need it your brain will tell you to choose it.

How to judge whether the quality of PCB FR4 is up to standard?

To judge the quality of PCB FR4 firstly check if it meets your requirements and then keep in mind a few things when selecting FR4 material such that it can produce many types of a printed circuit board. Check design and flexibility; most manufacturers recommended thick boards to thin ones. These are some points I told you which will help you to judge the quality of FR4 material.

printed circuit board


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