PCB Board Size: What Should You Consider?
PCB Board Size: What Should You Consider?
Printed circuit boards are found in electronic devices of various sizes. You will find them in watches to home appliances to industrial equipment, and almost all electronic devices. Although all these printed circuit boards perform the same function – powering the devices and their performances – they differ in many ways. These differences may not be easily visible unless analyzed minutely. The most obvious difference is the PCB board size. PCB designers understand the importance of choosing the right board sizes and have been rightly doing so. Having said that, choosing the right PCB board size may not be easy as it sounds. It requires several considerations. What are they?
Know the Different PCB Board Shapes
Before getting into the details of different PCB board sizes, it is important to check on the few board shapes. The following are a few common ones:
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Tiny and highly dense PCBs used in digital watches
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Circular shaped printed circuit boards for special devices
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Thin boards that can be used around CRT
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Printed circuit boards for industrial equipment
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L-shaped printed circuit boards for glass screens
Although most PCBs are rectangular or square shaped, their sizes vary depending on application requirements, but the design rules will remain more or less the same. The next section introduces you to factors that need to be considered for the PCB board sizes.
Factors to Consider When Deciding the PCB Board Size
The PCB board size not only has a direct impact on the functioning of circuits, it also impacts the budget and deadlines. Here are different factors to take into consideration when deciding on the PC board size.
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Number of Layers: It is important to consider the number of track layers needed in the PCB. Remember additional layers may increase the production costs, and also the number of tracks as well as the overall board size. Complex board designs may require several tracks and it may not be easy to route them easily.
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Address the Track Design: Along with the number of track layers, the track sizes also matter. When deciding the PCB board size, it is important to take into consideration the track created on the bare board. If the tracks are created farther then the number of tracks in any area would be restricted; however, if they are created closer, there may be shorts or other connectivity problems. Also, in case the tracks are located farther, additional planes would be needed to route the PCB.
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Mounting Components: The number of mounting components would depend on the applications where they are to be used. For instance, the PCB for a digital watch would require fewer components than a PCB for a computer laptop. Similarly, the PCB for industrial equipment may require more components than a PCB for a laptop. Hence, it is important to consider these factors when designing the PCB. To avoid conflicts, it is always recommended to leave at least a half-inch space on all sides after the placement. This calculation can be easily done using the CAD software in the initial design phases.
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Address the Board Mounting Method: Through-hole and surface mounting are two types of board mounting generally adopted by PCB manufacturers. Each of these methods has their own pros and cons. It is necessary to understand what components would be mounted in the beginning and how they would be mounted. Both these mounting techniques may require some free space on the board. So, plan accordingly.
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Leave Sufficient Cooling Space: Thermal issues are rarer for small PCBs. However, these thermal issues are common for PCBs with high component densities and processing speeds. Some components may dissipate high amount of heat, so they may require additional space for heat sinks.
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Tolerance Value: Manufacturing tolerance is another consideration to be made when deciding on the PCB board size. Tolerance is a term for the variation that is allowed in any PCB in terms of measurement and other variables. Manufacturers like Twisted Traces consider the tolerance value of ±3mil.
Being the most important feature of several electronic devices, choosing the right PCB board size is immensely important. It requires several other considerations in addition to the ones mentioned above. Sometimes arriving at a conclusion requires more than just expertise. To avoid confusion and minimize the chances of failure, it is always recommended to partner with the right company. Twisted Traces has been helping its clients to build performance-driven and value-centric PCBs for several years now.
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