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As part of our best practices and information for new designers and hardware startups, we want to give new designers the information they need to choose the right PCB for their next project. Any PCB is intended to provide a physical support for an electronic system and its components. The complexity of different types of PCBs varies widely, depending on the function of different circuits. If you’re designing a PCB for the first time, we’ll show you the different types of PCBs that will hopefully provide inspiration for your next project.
As the name states, these boards have a rigid substrate which prevents bending or warping. These are usually made of solid, rigid material like fiberglass weaves, but more demanding industrial or automotive applications may require ceramic or metal core substrates. With the number of layers ranging from one to more than ten, they are the most common type of PCBs on the market.
Just like its name suggests, a single-sided PCB consists of a single layer of conductors and components. There is usually a solder mask over the copper layer, and silk-screen can be used to mark the positions of different components. Despite the low-cost, the utility of these boards is limited because of the design complexity limitation. Due to only one surface available for connections the area of the board can grow very fast to accommodate all the components and connections.
Double-sided PCBs are similar to single-sided except the conducting layer is on both sides of the substrate. Now the connections can run on both sides of the PCB, hence it occupies a smaller area or can have more complex circuits. The connection between top and bottom layer is made using plated holes called “vias”. These boards are used for moderately complex circuits. It is generally not a good idea to try and design high-speed or high-frequency PCBs on double-sided boards as grounding and power distribution can be a real challenge, especially as the number of components increases.
Layers in a double-sided PCB
Multilayer PCBs have several layers of copper separated by insulating laminate materials. Connections between layers are also made using vias. Typical multilayer boards start with four layers, and the layer count grows for more complex (and costly) boards. The extra planes can be used for routing, power distribution, and grounding planes, which helps to reduce crosstalk and electromagnetic interference (EMI). A four-layer board is usually a good place to start for a moderately complex board that will run at high speed (faster than TTL logic) and/or high frequency (usually hundreds of MHz or higher).
Layer stack in a multi-layer PCB
Rigid-Flex PCBs are a middle ground between one of the previous types of PCBs and a flex PCB (see below). These boards are best used in applications where a board requires precise molding to its enclosure or when different sections of a board need to move with the enclosure. These boards are also useful in small spaces where a standard connector will not fit in the enclosure. These boards can be found in pacemakers, digital cameras, and cell phones.
Rigid-Flex PCB from RayPCB
These boards are not really boards; they are fully flexible PCBs that can be molded into nearly any shape without affecting circuits present on different layers. The substrate is usually made from polyimide with copper or other malleable metal used for conductors. These boards are more expensive than the other types of PCBs due to the additional fabrication complexity.
Which Type of PCB is Best for Your Design?
The answer to this question really depends on the application in which your board will be used, your production budget, and the level of complexity of your circuits. One rule of thumb that will aid in your decision is this: if your new design works properly on a breadboard, you can expect your circuits to work as designed no matter how you layout your PCB.
For designs that run at high speeds and or frequencies, single-layer or double-sided boards are typically unsuitable, and you’ll want to start with a four-layer PCB. Here are some other points to consider for different types of PCBs in certain applications:
- PCB for medical devices have severe area constraints therefore require dense routing with compact footprint. Multilayer PCBs are therefore quite common in medical and other advanced applications.
- Industrial applications usually have high current requirements than in other applications. PCBs used in these cases have a thicker copper layers compared to normal PCBs.
- Automotive and aerospace PCBs must withstand strong mechanical vibrations, hence flexible PCBs can be used for such cases.
No matter which types of PCBs you want to design, Upverter® provides the schematic design and PCB layout tools you need to design boards from start to finish in a browser-based interface. If you are preparing a complex PCB with multiple layers, Upverter gives an easy EDA teamwork platform for a live multi-user collaboration and real-time design rule check (DRC) features.