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Difference Between Rigid PCB and Flexible PCB

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Tues, Nov 12, 2019

Printed Circuit Boards are an essential component of electronic appliances and gadgets. Without printed circuit boards, the functioning of electronic gadgets will be impossible. The printed circuit boards are responsible for the smooth flow of electricity within an electrical circuit. Different gadgets require different types of printed circuit boards. There are two major printed circuit board types;

·  Rigid Printed Circuit Board (Rigid PCB)

·  Flexible Printed Circuit Board ( Flexible PCB )

Traditionally almost all electronic devices used rigid PCBs. However, with time and increased knowledge, more and more electrical engineers are moving towards using flexible printed circuit boards. All conventional devices can work with both types of printed circuit boards. However flexible circuit boards are ideal  for complex electric circuits. Almost all new and modern electronic devices use flexible circuit boards or a combination of rigid and flexible PCBs . Such circuits are known as Rigid-Flex PCBs. Even though many electronic devices can work with both types of circuits and a combination of both circuits can be great, there are still some very significant differences between the two printed circuit boards. Let’s take a look at some of the differences between the both circuit boards.

The Difference Between Rigid PCB and Flexible PCB.jpg

Flexibility

As clear from the name the flexible printed circuit board can bend and twist however a rigid circuit board cannot. The flexibility of the flex circuit gives it a lot of advantage more the rigid printed circuit board.

Manufacturing Process

When it comes to the manufacturing of both rigid and flexible printed circuit boards, you can find a lot of differences. Whether it’s making of the design, manufacturing process, and use of certain materials. The materials used to make a flex circuit are significantly different than the materials used to make a rigid circuit. The flexible printed circuit board is covered with flexible lamination whereas a rigid printed circuit board has a solid solder mask. This also results in lower weight for the flexible printed circuit board.

Thickness Level Of The Board

The rigid printed circuit board is thicker than flexible circuit boards. The flexible printed circuit boards can be very thin. They can get as thin as paper. You can even find flexible circuit boards as thin as 0.2 mm.  As clear from the name the flexible printed circuit boards need to be thin as some electric gadgets might want bendable printed circuit boards.

Softness Of The Circuit Board

The softness level of both the circuit boards can be judged by their second names. The rigid PCB is also known as a hardboard and the flexible circuit board is known as soft board. The flexible circuit board has to be soft as it needs to bend and twist.

Shape Of The Printed Circuit Board

When it comes to the shape of printed circuit boards, the rigid board has a somewhat standard square and rectangle shape whereas flexible printed circuit boards can vary in shape. Mostly the shape depends on the type of electronic device the circuits are going to be used in. As flexible circuits are mostly used in complex electronic equipment they have to shape in ways that can fulfill each unique and customized need of each individual electronic appliance.  This is also the reason that flexible circuit boards have a bendable shape.

Designing Of The Pad On The Board

The flexible printed circuit board faces a very specific issue with pads on the circuit board. As you can bend the flexible circuit boards, it is very important to keep the pads away from the bending region. If the pads are on or near the soft bending area then it can cause problems in the smooth flow of current.

The Capacity To Carry Current

When it comes to carrying current, the rigid printed circuit board is better as compared to flexible printed circuit board. The flexible circuit board can have a bending shape that does not encourage smooth flow of current whereas the rigid printed circuit board can have a straight line of current. This boosts the carrying capacity of the rigid printed circuit board.

Space Take

If you are looking to have complex circuits placed in a small device then the best option for the printed circuit board to go for is the flexible circuit board. The flexible printed circuit board can be bent in any shape to fit the size of the respective device.  This is why most of the smaller devices these days like mobile phones and tablets use flexible printed circuit boards.

Cost Of The Printed Circuit Boards

There is no specific way to calculate the price of a circuit board as the price of the circuit board may vary with the difference in shape, size, type, and design.  Generally , the rigid circuit boards cost less as compared to the flexible circuits. However that is not always the case. The flexible circuit boards usually have lesser components that reduce the material and assembly cost of the end product. So in such cases the flexible circuits are more cost-effective.

Conclusion

Both flexible circuit boards and rigid circuit boards have their own unique features. They both serve the same purpose but it is crucial to know which type of board would work best with your circuit. Some electronic equipment may work better with rigid circuit box while some might work better with flexible circuit boards. Most of the modern circuit boards work on a combination of both rigid and flexible circuit boards. These types of circuits are called Rigid-Flex Circuit Boards and highly skilled and knowledgeable engineers these days focus on such types of circuit boards. The Rigid-Flex circuit uses the uniqueness and differences between the two types of PCBs to create a more effective circuit board that can work with almost all types of electronic equipment and appliances.