All You Need to Know About What Is FR4 PCB Material

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Different materials are available in the market on which you can build a PCB. One of the best materials that are also flame retardant is FR4. Now you might be wondering what is FR4 PCB material? Plus, how it can be flame retardant.

In further detail, we will discuss what is FR4 PCB material and every other fact about this PCB material that high-tech companies use to build high-tech PCBs with FR4 material.

What is FR4 PCB material?

FR4 PCB is square grid glass strands that are woven together. After the glass grid is woven, it gets impregnated with epoxy resin. It will be semi-cured, so it becomes a ply of prepreg. It gets ready for the next step so that you can start inserting the PCB material on the FR4 PCB. An FR4 PCB meets the UL64V-0 requirements.

Role of FR4 PCB material

If you are looking for the answer, what is FR4 PCB material? FR4 is the base material of a PCB that is flame retardant. It is a glass fabric composite. The FR stands for flame retardant and meets the UL94V-0 requirements. Let's talk about the role of FR4 PCB material in the whole PCB manufacturing procedure:

A flame-retardant epoxy resin

While you will be preparing an FR4 PCB, there will be less smoke and more thermal resistance with amazing mechanical properties.

Minimal water absorption

FR4 PCB has minimal water absorption. So, it is one of the best PCB material options because water won't be able to affect your PCB.

Types of FR4 PCB

There are two main types of FR4 PCBs. So let's discuss them a little here:


A comparative tracking index has a higher electrical resistance of approximately 600 Volts.


You might have gotten the idea of this FR4 PCB type that has got more heat resistance as compared to a simple FR4 PBC. This type has more glass transition of approximately 180 degrees Celsius.

Pros of FR4 PCB

Following are the pros of FR4 material usage to prepare a PCB:

Works for standard applications

FR4 PCB is used in standard applications. You should know that with a PCB, no electrical device would function properly. Therefore, you will have to install a PCB in the device for the current flow. For standard applications like radios, TV, remote control, and home appliances, an FR4 PCB would be a good option.

So, the number one benefit of using an FR4 PCB would be it has good mechanical resistance, and the current will flow through it without getting disturbed.

Maintains high mechanical strength

As we have said above, an FR4 PCB comes with high mechanical strength, and it would be the requirement of electric devices in which you are going to install it. With high mechanical strength, there would be no current flow problem, so that the device would work perfectly.

Works in humid and dry environments

Most of the time, the PCB made up of standard material stops working because of environmental conditions. If the surroundings are too humid or the environment is dry, then the PCB might be affected. When it comes to FR4 PCB, these environmental details don't affect its working. Yes, an FR4 PCB would work perfectly in humid and dry environments. Therefore, most of the time, tech people prefer to install such PCBs in devices working in such dry conditions.

Otherwise, you will have to keep replacing the PCB of your electric device because the dry environment will affect it. The current won't be able to flow through the PCB, and the device wouldn't get it.

PCB material

A compact PCB size

Do you think a full-size PCB would fit if you are manufacturing a remote control? Well, a compact-sized PCB would work in smaller devices requiring current work. Therefore, you choose to get FR4 PCB for such a device. An FR4 PCB can be constructed in a compact size, which is why we have mentioned this benefit above already.

It works for standard appliances where space would be an issue. The PCB's size must be compact to fit in that device. A compact-size FR4 PCB would fit easily in standard-size applications.

Water-resistant and durable

What if you drop water on the PCB? Most of the time, a short circuit might take place there is also a possibility that your PCB would stop working. Water is the enemy of electrical devices. You might have to dry the PCB, and there are minimal chances it will work again.

This won't be the case if we discuss FR4 PCB because it is water-resistant. No one drops water on a PCB intentionally, but sometimes it happens mistakenly. An FR4 PCB won't get affected by it. So, an FR4 PCB is a good option because it is water-resistant and durable. If a PCB is durable, then it will last long. So, it is another benefit of using FR4 PCB in your electrical devices.

Signal integrity with no interference

If the signals get dropped, or the current flow gets disturbed, then the PCB won't be able to allow the device to work properly. The signals on PCB can get disturbed for any reason if the quality of the PCB is poor. An FR4 PCB has more signal integrity compared to any other PCB material.

The current flow on an FR4 PCB will not be disturbed by any factor. You will be able to operate your device. So, if you want to install a PCB in a device that should always work and the current flow doesn't get affected, then FR4 PCB is the right choice.

An ideal option for a high-temperature environment

There will be electrical devices that you will use in a high-temperature environment. Most of the time, standard quality PCBs won't be able to handle the heat and high temperature. There is a great possibility that such PCBs might even melt at such high temperatures. Still, an electronic device would require a PCB to work. FR4 stands for fire retardant, and it can resist heat. FR4 PCBs can handle high heat and temperature environments.

They won't get melt, and it is one of the best options for types of machinery that you use in companies and manufacturing plants. The high temperature won't be able to cause any damage to FR4 PCBs easily. So, the last benefit of FR4 PCB on the list is their resistance to high temperatures.

Cons of FR4 PCB

We have talked about the positive side of FR4 PCB, but it also has a negative side. We have talked about the pros of FR4 PCB. So, now it is time to discuss the cons of FR4 PCB following are the disadvantages of using FR4 material in the manufacturing of PCB:

Lead-free soldering doesn't work for this material

An FR4 PCB is made up of epoxy resin with woven glass, and if you try lead-free soldering on this type of PCB, you will ruin it. Yes, an FR4 PCB doesn't support lead-free soldering because of its material. The lead-free soldering temperature would be quite high, and it might affect the material of the FR4 PCB by altering its laminated surface.

So, the number one disadvantage of manufacturing an FR4 PCB would be that it doesn't support lead-free soldering because it will cause changes to the surface of the PCB and might ruin it.

Fabrication and designing take time

The fabrication and designing are going to take a lot of time if you are going to do it on FR4 PCB. You must be careful with every move because you might damage the surface. This negative point about FR4 PCB makes them a little less desirable. Manufacturing FR4 PCBs will take so much time compared to other PCBs that the companies prefer to manufacture simply PCBs.

The manufacturing of standard PCBs is the preference of PCB manufacturing companies because they don't have to invest a lot of time in the fabrication and designing of FR4 PCBs.

FR4 PCB with high frequency is a bit expensive

The cost of the FR4 PCB depends on the frequency. The manufacturing cost will be low if you build a low-frequency FR4 PCB. If you get into high-frequency FR4 PCB manufacturing, then it might cost you a fortune.

So, yes, high-frequency FR4 PCBs are expensive compared to other PCBs that the companies are manufacturing in large quantities. If you compromise on the quality of FR4 PCB material and build a low-frequency FR4 PCB, then it might not work for those electronic devices that require high-frequency current and signals to operate.

Final Remarks:

Now you know What FR4 PCB material is and how it works for PCBs. Now you know both the positive and negative sides of FR4 PCB. Well, the benefits are more than the negative points. FR4 PCB is surely a good option because of the high-quality material and the properties it has. It would work perfectly for most electronic devices.


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