What Is The Difference Between Rigid PCB And Flex PCB?

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Whenever we hear the word PCB or Printed Circuit Board, our brain anticipates a circuit board that is green in color. There is no second option even though circuit boards are also made in different colors. However, looking today at the PCB world and KingfordPCBA, we can see how far things have come.

Now the PCB world has transformed a lot, and several different types of PCBs are available. Two of those types are Rigid and Flex, the most common ones. As they are the most common ones, there is always a hot discussion about which one is better. So, we are here to finish the debate for you by providing all the facts that you need to know.

What is a Rigid PCB?

As the name speaks for itself, this type of printed circuit board is rigid in its structure. This circuit board cannot be bent. Similarly, you cannot force it out of its shape, or it will crack/break. This may break the connection prints, ultimately ruining the whole circuit board. The reason for having such a structure is that it is made from silicone which forms into hard sheets upon treatment.

What is a Flex PCB?

The naming convention here is pretty much self-explanatory as well. The flex PCB is a printed circuit board that can flex, or you can bend/twist them up to a certain extent. Unlike rigid PCBs, these are made with a different material that allows them to be flexible.

The differences between rigid PCB and flex PCB

A general overview of these PCB types tells that there will be a lot of differences between them. Whether you consider the working or properties of the PCB, there are many differences. So, here we have gathered all of them to help you understand these PCBs in a better way. Below are the differences between a rigid PCB and a flex PCB.

The shape of the PCB

The shape is the factor that matters the most for any PCB. PCBs are mostly made to fit inside devices and electronics. Usually, manufacturers are looking to make those PCBs fit inside as tight spaces as possible. The rigid PCBs come with a mostly rectangular shape, and there are mounting holes.

On the other hand, the flex PCBs do not follow the shape as a major factor. Those are mainly made in free shapes, so the flex PCBs are usually longer. Going with flex PCB is that they provide more safety if the device has a slight change in shape.

Flexibility and brittleness of the PCB

Next up is the flexibility and brittleness of these PBCs. It is one of the biggest differences between these PCBs because these two factors usually differentiate them. So, when it is on the flex PCB, it can be very flexible, and you can flex, bend, and twist it as per requirement. However, it is prone to tearing under a lot of pressure.

On the other hand, the rigid PCB comes with a solid structure with no flex, but this cannot be torn because you are not flexing it. The rigid PCB can also face failure because of its brittle structure if put under high pressure.

Capacity to carry current

Another difference that most people do not care about is the capacity to carry current. This may sound weird, but these two PCB types are very different when carrying current through the printed paths. These circuit boards face a heated issue due to the passage of current.

So, it is always better to use thicker wire prints, especially on the flex circuit, because their soft material can cause them to bend, and then a short circuit can happen. On the contrary, a little heat is not a major issue for the rigid PCB from KingfordPCBA.

PCB

Contact pads on PCB

There are different parts and sections on a PCB, and one of the most sensitive parts of both PBC types is the contact pads section. In the rigid PCB, you mostly see that these pads do not get a lot of protection. It is not needed as well because of how well built and strong these PCBs are.

However, that is not the case with the flex PCB. You can easily bend that part of the PCB and cause the whole circuit to fail. This is why flex PCB comes with an additional layer of protection by KingfordPCBA. This protection can be a film and some hard material to avoid bending.

Base materials for making PCB

Another major difference in these PCB types is the material used to make the base of the PCB. For example, the rigid PCB is made with glass/silicon as its base material. This is the reason for the strong and thick structure of the PCB. It is also the reason for the reinforcement of this PCB in all the devices.

The material being a major difference in these PCBs, the flex circuit boards are made with Polyimide. This structure does not provide a lot of strength or thickness but allows the circuit to be flexible.

Manufacturing process

With the different materials, the manufacturing process is also very different in both of these options. For the rigid PCB, the main process in manufacturing is a solder masking process. On the other hand, the Flex PCB is made with a cover layer of material known as an overlay. As the circuit here is flexible, it makes sure that everything is covered and protected underneath.

Weight of the PCB

When we talk about making consumer electronics, the weight of the PCB matters a lot to the manufacturer. This is also a quality that is different between rigid and flexes PCBs. For instance, the Flex PCBs are made thinner, which is why they are very lightweight. On the other hand, the rigid PCBs are made with a thick layer of material, making them heavier than the flex PCBs from KingfordPCBA.

Resistance and toughness

Being made with different materials and having different shapes and structures also differentiates these PCBs in terms of their resistance and toughness against different touch situations. For instance, rigid PCBs at KingfordPCBA are more resistant and tough against bending or sudden pressure on the device. However, they will not bear tearing.

On the other hand, the rigid PCB is not that great at resisting impact or showing toughness against hard situations. However, you cannot pull it from 2 opposite ends to tear it apart.

Design sophistication

The design sophistication is a factor that makes rigid PCBs more applicable, at least for today’s world. These are mostly used in toys, computing devices, mobiles, and other consumer electronics. On the other hand, the flexible PCBs at KingfordPCBA are sophisticated in terms of design, making them only necessary for the complex product where using them is necessary.

Cost and savings

The last difference discussed here is the cost of making them and the overall saving these PCB types provide. Starting with the Rigid PCB, it is cheaper to make. So, the manufacturers can save a lot when producing these PCBs in abundance.

On the other hand, flex circuits are more expensive because of a unique material, different manufacturing processes, design sophistication, and many other factors. Although the cost is high, these KingfordPCBA PCBs can easily fit in tighter spaces, allowing engineers to design their products better.

So, products with better design and compact structure sell at higher prices, resulting in indirect savings for the manufacturers.

Which one from the rigid PCB and flex PCB will be the right choice?

Choosing between these two PCB types can be very difficult if you do not know all the important factors. For some applications, both are amazing, while for some, only one works fit. So, you need to consider the demands of your application like the following:

  • Does the product need to bend or not?
  • What will be the current supply requirements of the circuit?
  • What type of shape and structure does your product need from its PCB?
  • Your budget considerations is very important

When considering these, make sure to thoroughly compare both options and look for ways in which one seems better than the other one. This will be your best way to select one PCB out of Rigid and Flex when going for KingfordPCBA.

Verdict

Take a look around yourself, and you will see that almost everything around you has a PCB in it. Everything else will have a PCB in it, from the wall clock to the smartwatch on your wrist, from your computer to your mobile phone. So, we can see the importance of a PCB and KingfordPCBA in our life.

This importance is why today we are developing different types of PCBs that share some features and bring some unique features as well. The PCBs that we were discussing here was flex and rigid. Now we hope that you have a good understanding of both, and you can efficiently decide between buying one.

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