Rigid PCB: Definition, Types and Application

Rigid PCB , Most Common Used Type in PCB Manufacturing

There are plenty of PCB types in the industry, the most common is the rigid printed circuit board (PCB). These boards allow communication between the devices’ different components while maintaining their sturdy shape.

What is Rigid PCB? - Definition of Rigid PCB

Rigid PCB

A rigid printed circuit board is a board that can’t be folded or twisted. The rigid substrate gives the board strength that you might not find on other printed circuit boards. Once created, it cannot be modified.

Rigid PCBs composition includes a solid substrate, copper, a mask, and a silkscreen layer. The layers adhere to heat and adhesives to make either single-sided or double-sided. They may also be single-layer or multi-layer boards.

While several rigid boards may be found in computers, the most common is the motherboard. This essential component allows the different elements to communicate with one another. In addition, it distributes information such as GPU, RAM, and CPU.

Unlike flexible PCB, rigid PCB can only fit in areas of the computer where the printed circuit board must be a set shape, maintained through the machine’s life. They all fall into a typical application scope, whether it is a single, double, or multi-layer board.

Characteristics of Rigid PCB

There are several characteristics of the rigid PCB. To begin with, a rigid PCB has copper paths and trances incorporated onto a single board. These paths connect different board components.

Additionally, as the name implies, a significant characteristic of the rigid PCB is the solid substrate that makes up the board. This substrate keeps the board from flexing or changing shape, thus lending its “rigid” structure. It also makes this type of board stronger than flex PCB.

As these are printed circuit boards, they cannot be modified once the company manufactures them. Due to this fact, rigid boards are cheaper and more cost-effective than flexible boards.

Despite having limitations that keep it from being the only type of circuit board, rigid boards play an essential role in computer makeup. This is because they make up the critical components of a computer. An example of this is the motherboard.

How are Rigid PCBs Manufactured?

rigid pcb stackup

Rigid PCBs have different layers joined together by adhesives and heat. This gives the board its strong solid shape. Several layers make up the finished board. The layers are substrate, copper, solder mask, and silkscreen from the bottom up.

Substrate Layer

The substrate layer is the first layer in the manufacturing of rigid PCB. This layer is typically made from FR4 fiberglass. FR4 provides stiffness to the board that gives it a rigid name.

Alternatively, the substrate layer could be made from epoxies and phenolics. However, these aren’t as durable as FR4. On the other hand, they are cheaper, making them appealing to some manufacturers.

Copper Layer

On top of the substrate layer is a layer of copper. Manufacturers laminate the copper foil to the substrate and use adhesives and heat to ensure it is secure. In addition, the copper layer helps to transmit data along the different paths.

Most higher-end electronics use a double-layered board with both sides laminated with copper. Cheaper electronics, however, use a single-layered board which may affect its overall usage.

Solder Mask Layer

Manufacturers add a solder mask layer to protect the copper paths on top of the copper layer. The solder mask provides insulation which helps prevent damage should conduction material touch the copper layer.

Silkscreen Layer

The final layer is the silkscreen layer. This layer adds characters to the top of the board to help users understand the board better. While these characters are often silkscreened in white, they may be yellow, black, red, or gray.

Tips for Rigid PCB Design

When designing a rigid circuit board, there are a few things to consider. To begin with, carefully consider the board’s dimensions. These boards are fixed and cannot be altered once printed, so having the correct measurements is essential. Next, use a 3D printing application to design the board for accuracy when possible.

Next, consider the materials to use when printing the board. Copper is a necessity for current-carrying and controlled impedance. However, designers must know the variables to determine the best material choices. 

As the substrate can be made with FR4 fiberglass or phenolics and epoxies, thorough calculations are essential. With the calculations in hand, the fabricator can determine the best material to use.

Difference Between Rigid and Flex PCB

While both rigid and flex printed circuit boards are standard in electronics, there are significant differences in their design and usage.

As the name implies, a rigid board is a stiff circuit board that maintains its shape throughout its life. Therefore, it cannot be modified once the board is printed.

On the other hand, flex PCBs are flexible printed circuit boards that can be bent to fit if necessary. As a result, these boards require less space than their rigid counterparts. However, unlike rigid PCB, flex boards are mainly single-sided boards.

Flexible PCBs are more expensive to manufacture than rigid boards making them less desirable in specific devices. Despite their cost, they do have benefits that rigid does not. Not only are they flexible, but they also provide a better connection between other circuit boards, electronic components, and the user interface. They also are lighter and can absorb vibrations better than their rigid counterparts. Thanks to their flexibility, they are more resistant to warping.

Rigid PCB application

There are several typical applications as rigid printed circuit boards are among the most common boards found in electronic devices. These include:

  • Use as motherboards for desktop and laptop computers
  • File servers and storage devices
  • Found in cell phones and other portable devices
  • Used in medical equipment such as CT scans, x-rays, and pacemakers
  • Found in automobiles
  • Used as signal repeaters and GPS for mobile phones and other devices

Types of rigid PCB offered by PadPCB

PadPCB is committed to providing high-quality rigid PCB. PadPCB offers the following types of rigid printed circuit boards to meet customer needs.

The single sided PCB is ideal for simple designs and rapid production, these printed circuit boards have copper paths on only one side of the board.

double side PCB

Double-sided PCB

This type has two layers of copper pathways. The dielectrics are sandwiched in the middle and work well in high and low-temperature environments.

The multilayer board has more than two layers of conductive copper, such as 4, 6, 8 and so on.Equal dielectric layers separate each.

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