Knowledge Base

Single-Sided vs. Double-Sided vs. Multilayer PCBs

Creating a new PCB project is always very excited, with a lot of excitement comes also a lot of responsibility and consideration we need to take in order to ensure our project goes as smooth as possible. PCBs come in different sizes and different shapes, single sided PCB, multi-layer PCB, and how to go from prototyping those boards to the mass production stage.

Many things to consider including pricing, size, and components availability but in this article, we’ll mainly discuss the differences between Single-sided Vs. Double-Sided and Multilayer PCBs and PCBAs, the differences between them, and the things we need to consider before producing our first prototype.

Layers of PCB Design

If you are reading this, most probably you’ve made (or are about to make) a couple of PCB designs, depends on your project it might require different layers of design. starting from double (2 layers) PCB design and can go all the way up to 16 layers.

The layers depend on multiple factors, one of the factors would be the size of the PCB board. When we want to fit many components into a small area we might need multilayer PCB in order to be able to wire all the components successfully as each wire (PCB trace) runs across a single layer, two traces cannot overlap on a single layer thus we must use different layers in order to archive a complete circuit schematic design.

Another factor for designing multilayer PCB will be the complexity of the components that we place in our design, some components such as CPU or complex integrated circuits require multilayer PCB design with 4 or more layers, this is the requirement during the layout of such components and thus cannot be ignored.

Two or more layers designs mostly depend on the PCB project and the requirements of the size, components, and use case, the more complex the design is the more layers it will have. Multilayer PCB is very common these days and many PCB factories can process the customer's specific requirements for either single or multilayer PCB.

multilayer PCB manufacturing (4-16 layers) is often more expensive than 2 layers fabrication this is due to the increased complexity and the amount of cooperate and other materials used in multilayer PCB, if the design can be made with 2 layers, it will be recommended in order to reduce the cost of fabrication.

Etching the PCBs

You might be wondering how to etch double sided PCB, but first, what does etching even mean? Etching is the process of carving using a very high power laser across the surface of the PCB, this process is done in order to create the wire traces that are used in the custom PCB design circuit.

The etching process is very efficient and often used in the PCB industry and can be done either on single sided PCBs or multilayer PCB, this process eliminates the need of using toxic chemicals, ink, or acids which were traditionally used during the PCB manufacturing process.

Etching can be done at home as well but often requires expensive and dangerous chemicals and acids which could harm the environment, it can be done on cooper boards used for PCB fabrication as well as flex materials for production of a multilayer flex PCB.

a multilayer flex PCB is often made using sheets of polyimide material which has cooper on one or more sides of the sheet, the characteristic of the polyimide material is a very high melting point and flexibility which makes it perfect for manufacturing and creating samples of flexible PCBs.

Single Sided PCBA

Once we’ve decided if our PCB is two or multilayer PCB and if it will be a casual or flexible board, it’s time to consider on which side of the PCB the components will be placed.

Single sided PCB definition is when we place components on a single side of the PCB board (usually the top side) instead of populating the board with components on both sides of the PCB. However, Single sided PCB should not be confused with the number of layers the PCB has, that’s two different things. multilayer PCB indicates the internal wiring and layers of the PCB while the single or double sided PCB placement refers to the SMT process where we place the components on one side of the PCB board or both.

The PCB has only two sides, top, and bottom where we can place as many components as the design, layout, and space allows us to. A popular choice is single sided PCB, but unfortunately, as the design gets more complicated, there might not be enough space to fit all the components on a single layer, this is due to limited space available for the components and the number of increasing components a complex design might have.

Single sided PCB has many advantages, once the PCB is used as a solution or a product it’s easy to design enclosure or the board on a flat surface, this due to the fact that no components are set at the bottom layer, enabling the single sided PCB to fit nicely and easily with custom enclosures.

When choosing the single sided PCB components, it’s very convenient to choose DIP components instead of SMD due to the fact that we don’t need to worry about any conflict of components on the bottom side of the board as we only use a single sided PCB design, double sided PCB, on the other hand, will limit us over the number of DIP components we can fit in, by placing a DIP component we will have to create holes in the cooper to wire the components through, which will limit the ability to place SMD component at the same location over the PCB board, if the design use many DIP components, it is recommended to design a single sided PCB.

Another advantage will be that components usually create heat, by designing a single sided PCB we can ensure less heat spread over the PCB board which could benefit the board's long-term durability and stability. Single sided PCB price is often lower than multilayer PCBA this is due to the fact that only one layer needs to be assembled thus making it easier, cheaper and faster to accomplish during the mass production fabrication process.

Double Sided PCBA

Once we understand the advantages and disadvantages of a single sided PCB, let’s explain what double sided PCB is and compare single sided PCB vs double sided PCB.

The first obvious advantage of double sided layer PCB is that we have more place for components, the design could be made using 2 layers PCB but populated on both sides with components. However, When fabricating double sided PCB board prototype, the price will often be more expensive as for small batch of 1-5 pieces the worker will need to solder the components manually, on both sides. While the top side can be soldered with a small oven, the bottom side will need to be soldered manually, unlike single sided PCB where the entire board can be heated and soldered inside an oven or heating device.

Many customers wonder how to use double sided prototype PCB, the answer will be the same way as you’d use a single sided PCB. regarding usage and functionality, there is no differences except for things that should be considered such as enclosures or heat spread across the board.

Another advantage of double sided PCBA will be the ability to place more components on a smaller form factor of PCB, which means, we can design a smaller board but fit all the components on both sides of the PCB by taking advantage of both the top and the bottom layer in our design, single sided PCB has only the top side populated with components which might require a bigger size of PCB to be designed in order to compensate of the lack of space.

Conclusion & take-aways

We learned about different types of PCB designs such as single layer designs and multilayer PCB designs, we also went through the differences when it comes to the fabrication of single layer vs multilayer PCB manufacturing in terms of price and other things we should consider in advance. There is also the single sided vs double sided components population that we discussed and the differences it has in prototyping and mass production, the cons and pros, and what we should consider when making that kind of decision.

With that saying, PCBasic is an expert in field of single or multilayer PCB design as well as multilayer PCB manufacturing with over 15 years of accumulated knowledge, there is no doubt we can handle any type of design or fabrication requirements both for prototyping purposes and mass production of hundred thousands of pieces a day.

PCBasic works with top components suppliers and distributors as well as fabrication facilities of PCB that can handle 2 to 16 multilayer PCB fabrication with high accuracy and speed, eliminating uncertainties and risks during the fabrication of any PCBA project.

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