Until recently, the creation of efficient Printed Circuit Board layouts wasn’t exactly a pressing issue. Electronic devices were large, and PCBs weren’t restricted in size. Today, however, PCBs are smaller than ever before and sometimes even ultra-thin and flexible. Designers are now forced to put more powerful and complex PCBs on smaller boards. Unfortunately, the close proximity of components and traces increases the chances of failure. This means that PCB designers are investing significant resources into designing the most efficient and effective PCB layouts possible.
To do this, many large PCB manufacturers utilize teams of professional PCB layout designers. However, most PCB companies can’t afford such a luxury. As an alternative to this expensive solution, by following a simple process, it is possible to ensure that PCB layouts can be more efficient, compact, and effective than ever before.
Basic PCB Layout Considerations
Designing the perfect PCB layout isn’t an easy task. You most likely won’t find the right layout on the first try, but that’s okay. First, begin to draw your planned layout. Some things to consider include:
- Size Constraints: It is a good idea to discuss the required board size with your client. This is usually limited by the size of the electronic device. However, it’s possible that there is some leeway. The more surface area you can work with the better.
- Materials: What type of board will you be working with? Is it an ultra-thin or flexible board? Knowing the board material will influence your choice of components.
- Mounting: How will your board be mounted to the final product? It is necessary to sure that the mounting points won’t interfere with the PCB’s function. This is especially crucial when designing multilayer PCBs.
- Multi or Single Layered: Sometimes, your client may not have considered multilayer PCBs as a possibility. If the manufacturer has the capability, see if your customers are receptive to the idea; there is always a balancing act between cost effective production and reduction in size or footprint.
Trace Layout Considerations
You will need to ensure that your traces are properly placed. When working with today’s small PCBs, your traces can never be too efficient. Consider these basic points when designing your trace layout.
- Width: The volume of the trace will determine how much current it can handle (thickness and width of copper traces). Do some online research and determine just how large your traces need to be for their required load. If your traces are too small, your PCB may fail.
- Separation: As a general rule, it’s best to separate your traces as much as possible. If your traces are too small or too close together, your PCB can suffer from short circuits or other problems. However, on a small PCB, separating traces can waste valuable space. Find what works best for your design.
- Pad Size: Finding the right pad size will take a bit of research. You’ll need to know the pad requirements for the components you’ll be using. Often, this information can be found online or with PCB design software.
Electromagnetic Interference Between Traces
Accurately predicting electromagnetic or signal interference issues is nearly impossible. However, you can take some simple precautions to minimize crosstalk between traces. First, try to avoid running parallel traces for long distances. Parallel traces are notorious for causing high levels of crosstalk. Next, try to avoid intersecting traces. If you must, it is a common practice to intersect intersecting traces at right angles to minimize crosstalk.
When designing the PCB layout, you must not forget about the depaneling process. This will necessarily require you to collaborate with the manufacturer to determine which depaneling method they utilize. If high heat CO2 lasers are used, you’ll be limited in how close you can place sensitive components to the edge of the board. If newer technology such as UV Lasers is to be used, you’ll have much more space available.
Implement PCB Design Software
Even the most experienced PCB layout professionals can’t compete with the utility of CAD or DFM software. Software offers two basic functions. First, it can come with graphic interfaces that allow you to easily design your PCB layout on your desktop. You can search for components and quickly make changes to your design without having to start over. Second, software can have built in simulation functions. This means that it can predict which areas of your layout may cause potential problems.
Efficient Layouts are Critical
With today’s complex components packed onto such small boards, the risk of failure is greater than ever before. Designing PCB layouts by hand simply isn’t as practical as it once had been. As a result, all PCB designers need to take some time and properly educate themselves regarding how to design layouts for today’s electronics. A quick way to do this is by learning how to use CAD and DFM software. By using proper software and these basic tips, you’ll be well on your way to designing the perfect PCB layout.