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Large PCB Board Sizes: Standards and Manufacturing Challenges

Large-PCB-board-panel-measuring-several-inches-long-and-wide
Large PCB board panel measuring several inches long and wide
Large PCB board panel measuring several inches long and wide
Resource: https://www.youtube.com/watch?v=ljOoGyCso8s

Printed circuit boards are made in many different sizes, including the not-so-common large PCB board. Depending on the intended use, this type of board is also available in a variety of dimensions, among other features such as layers and trace requirements. These, and everything else about the large format PCB, are discussed at length in this article.

What is a Large PCB?

A large PCB describes any printed circuit board whose dimensions exceed the range of conventional boards. But since size is relative, one board will appear small in its setting and large in another application. In light of that, we’ll begin our guide with a brief look at the options when it comes to PCB sizes, before discussing the large printed circuit board in detail.

PCB Size

A printed circuit board can be small and only a few inches long and wide, or large and measuring several inches for both dimensions. Note that PCB size also includes its thickness. However that only mostly ranges from about 0.005 to 0.039 inches.

Several factors influence the choice of PCB width and length or thickness. These include the number of components, clearance needs, stack up features, and so on.

When many components must be assembled, for example, a large size PCB board becomes necessary. This is seen in specific industries such as telecommunication systems or motor controllers and large television sets.

But even then, the sizes of circuit boards vary greatly across different industries. With that in mind, what printed circuit board dimensions are considered standard? Let’s see below.

Standard PCB Board Sizes

While no specific size can be called standard, a range of dimensions are common across applications. For instance, most printed circuit boards used in consumer devices are small sized, with only a few exceptions. To put that into perspective, here is a mention of the most common circuit board sizes.

PCB length and Width

Most circuit boards manufactured today have dimensions that do not exceed 24 inches length and about 18 inches wide. For that reason, PCB manufactures use what is called penalization to fabricate circuit boards.

That means using standard PCB sizes called panels to combine many similar boards in one device during the manufacturing process, which helps reduce costs. Common PCB panels, and what could be taken to be industry standards, include the following: 24” by 18”, 12” by 18” and 24” by 9”.

Note that these panels have a 0.5” margin on all sides and 0.1 inch spaces between the individual circuit boards that make them. Also worth noting is the fact that the 24 by 18 inch panel is the most common, and what many companies will use to make different PCB sizes.

PCB Thickness

For a long time, the industry standard for PCB thickness has been 1.57 mm or when changed to inches, about 0.062”. Depending on the specific requirements, a board may deviate from this thickness.

Large size PCBs, in particular, are generally thicker. On average, most options for PCB thickness, as stated earlier, range between 0.005” to 0.039”

An example of a large size PCB board panel
An example of a large size PCB board panel
Resource: https://makezine.com

Large PCB Board

A large PCB board is defined as any board that goes beyond the standard sizes mentioned earlier. However, that also depends on the respective industry where the board meant to be used in. Take for example, a type of board used on some household electrical or electronic products.

For this application, a board that measures around 24” by 12” would be considered large. On the other hand, huge PCBs that measure up to 55 inches long and over 22 inches wide are common in industrial applications.

How Big is a Large PCB Board?

A large PCB board is a big as its custom requirements for both length and width or thickness. Most often, this is a circuit board that exceeds 10 inches width and 20 inches width. Note that design constraints and assembly requirements apply when it comes to making large circuit boards.

The largest PCB boards are used industrial settings and communication networks. In addition to holding so many electrical or electronic components, these are PCBs that have to connect to high energy power supplies and cables, and that can be as large as 55” long.

Smaller PCB boards but whose dimensions exceed normal or standard sizes can be found in large electrical equipment and appliances. Although these may not be comparatively large, they present a segment of circuit board sizes that go beyond what considered conventional.

Maximum PCB Size

PCB size is mostly determined by its targeted application product and other factors such the number of components it must hold, the size of the copper traces, the number of layers, and clearance requirements, among other features.

Manufacturers will also often have the maximum PCB size that they can fabricate. For example, one manufacturer may be able to fabricate 54” by 22” large format boards, while another can only make PCBs that are slightly smaller.

When choosing a large PCB manufacturer for your project, therefore, its advisable that you understand their capabilities, and that include their options for maximum board size. Next, we take a look at what making large area circuit boards entails.

Inside a large PCB board Manufacturing and assembly plant
Inside a large PCB board Manufacturing and assembly plant
Resource: https://www.youtube.com/watch?v=24ehoo6RX8w

Large PCB Manufacturing

Large printed circuit board manufacturing is composed of 3 major stages: design phase, prototyping, and mass production. These are explained below. Note that you can also design your board and present the design file to the manufacturer.

Large PCB Design

If building your large PCB from scratch, the manufacturer will embark on the process to design it. This includes creating the board’s schematics and layout before generating the Gerber files that will be used to fabricate it. The large PCB design process, owing to its unique requirements, requires the designer to ensure the following measures;

  • That the board’s signal integrity is taken care of
  • That power distribution is optimized, given the many components and board size
  • Ensure proper thermal management by incorporating the necessary parts and design requirements for heat dissipation
  • That the layering or stack up is designed in a way that allows the board to perform as required, especially when high speed signals are involved

Based on your project needs, the manufacturer will assess your design and advice on various issues such as what can work and what will not work, or the best materials to use, among other things. Some of the materials at your disposal include normal and high Tg Fr4s, aluminum backed substrates for mechanical stability or heat dissipation, and so on.

Large PCB Prototype Board

Before large-scale production can begin, products are normally prototyped. The large circuit board is no exception. The prototype allows the manufacturer to test your design and pass it as viable to proceed to the manufacturing stage.

For large PCB manufacturers or companies, this is an important step, given the higher costs when it comes to making large boards, both in terms of materials and tooling needs.

Since large boards are mostly used in higher power systems, the manufacturer will usually test the prototype on these major parameters:

  • Material performance
  • Electrical properties
  • Thermal management
  • Mechanical stability

Large Production PCB

After the design and prototyping stages, the manufacturer will produce your large printed circuit board. This requires specialized equipment than what is usually used for standard sizes boards. Generally, the process to fabricate or assemble large format PCB boards is characterized by the following:

Higher Cost: a large board will generally cost more to fabricate. That’s because it uses more materials, in addition to requiring more personnel and other resources such as specialized equipment. The actual price will, however, depend on the design complexity and specific size.

Longer Turn-Around-Time: with its bigger surface area, a large size PCB board takes longer to design and fabricated than regular boards. Your manufacturer can provide you with an estimation of the turn-around time, and these are different across different companies.

Again, the actual TAT will largely depend of the complexity of your project. Also, the number of boards that you want designed and manufactured, among other considerations.

Fabrication and Assembly Challenges: when the PCB is too big, it often may not fit conventional automation assembly methods such as component placement robots or jigs.

In some cases, therefore, the manufacturer may need to install new equipment. Most often, though, large PCB fabricators indicate the maximum sizes that can make. This eliminates the need for changes.

Conclusion

Large PCB boards, despite being more demanding to fabricate, play a crucial role in settings where normal sized circuit boards would not fit. These range from industrial to communication applications, among other crucial uses. In addition to offering more real estate for component assembly, these PCBs can be used in high power systems. But that’s only if they are carefully designed and manufactured.

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