Printed circuit boards (PCBs) are essential for modern-day life, but learning the ins and outs of what is often a complicated subject can be intimidating. Our PCB for beginners guide helps you understand the basics of printed circuit boards, so you will be more familiar with components and materials should you decide to design your own custom printed circuit boards for a prototype or new product.
What is a Printed Circuit Board (PCB)?
A printed circuit board, commonly called a “PCB,” is a (usually) rigid board printed with electrical circuitry called traces. Components and layers can then be added to engineer and build a nearly limitless array of designs fulfilling most any need. While the fundamentals of printed circuit boards seem simple at first, once you begin to design your own circuit boards the complexities are noticed quickly.
A layer of protection for leads that prevents oxidation and sometimes acts as a safeguard against solder bridges and shorts when solder pads and/or traces are especially close together.
The silkscreen layer is typically white, but can be other colors, and serves as a reference guide and sometimes contains decorative graphics.
Pads are areas on the printed circuit board that have exposed metal in order to connect components to the PCB. Typically, solder is used to adhere items to the surface of the pad, but there are many choices for both pad design and methods of establishing connections.
In printed circuit boards, you will hear the term “layers” quite a bit. While you may hear a PCB being referred to as a “single layer PCB” and think of it in terms as in reality, even a single layer PCB contains multiple layers of material in order to operate correctly. These can be 2 layer PCB, 4 layer PCB, and so forth. Typically, when a printed circuit board is referred to as having a certain number of layers, they are counting the number of conducting patterns.
The footprint of a printed circuit board is the blueprint of where the components will be attached to the board itself, including where the pads and through-holes should be located.
Jumpers are typically pins, either insulated or non-insulated, used as conductors. They may be incorporated into a PCB design either due to minimizing PCB costs by reducing the number of traces and/or layers in a board design, or to make a PCB that can be configured multiple ways by cutting certain jumpers. Jumpers used to be used regularly in PCB design, but are less common in modern PCBs.
Via or Thru-hole Via
A via is a plated hole wall that goes through part of the printed circuit board to provide a path that can connect the electrical signal from one layer to another. There are different types of vias, but the most common type of via, called a thru-hole via, is a hole that goes from the top of the PCB all the way through to the bottom.
A blind via is very similar to a thru-hole via, but the hole stops at some point, and does not extend all the way through the printed circuit board. Since blind vias are closed at one end, the plating process can be more difficult, which means increased costs.
Buried vias are contained within an internal structure, and do not have an external opening. Since buried vias are laminated over, it saves space and allows for more elements to be added to the external layers. When creating small PCBs, there often wouldn’t be enough room to add components if one were to use a thru-hole via.
The copper traces on a printed circuit board act in a similar way to wire. When a PCB is created, a thin layer of copper is attached to the board, and the pattern of the traces is overlaid with an etch-resistant coating. This allows the rest of the copper to be removed from the board. The copper traces on PCBs are more precise and much faster to create than traditional wiring.
An annular ring is the ring of copper that encircles a via. Annular rings are important because they serve as the point of contact for the connections between layers on a PCB. Vias created for this purpose are typically larger than other types of vias, and the diameter of annular rings can have an effect on your overall design.
Design rule check (DRC)
When you are designing your printed circuit board, you will run design rule checks (DRCs) regularly while creating your layouts and schematics. A design rule check makes sure that your design fits the parameters set for the manufacturing process.
Gerber files are the industry standard format for PCB manufacturing. You will save your PCB design as a Gerber file to give to your manufacturer so that your printed circuit boards can go into production.
Printed circuit boards are classified in any number of ways, depending on the design, utilization, and other features. Just a few of the many ways to classify printed circuit boards are listed below.
Classification based on the mounting technology used
- Through-hole PCB – components have leads that are connected through the board, rather than only soldered onto the surface. Through-hole PCBs are able to withstand more stress, vibration, and movement.
- Surface Mount PCB – components are connected by soldering them to the surface of the PCB. Surface mount PCBs are less expensive to manufacture, and faster to produce.
Classification based on the number of layers
- Single Layer PCB – Single layer PCBs are the simplest type of printed circuit boards, having only one layer of traces. They are inexpensive to produce, and simple to design. Single layer PCBs are used in applications such as calculators, power supplies, and printers.
- Double Sided PCB – Double sided printed circuit boards are similar to single layer PCBs, but they have traces on both sides of the board. Double sided PCBs are some of the most common printed circuit boards, since they are able to be produced at a similar price point to single layer PCBs, but with more space available for circuitry and design elements.
- Multi-Layer PCB – Complex printed circuit boards typically feature 4 or more layers that allow for unique, intricate designs, for high-tech applications.
Type of PCB based on their flexibility
Sometimes, printed circuit boards are classified based on their flexibility, which defines what applications they can be used for. Common categories of PCBs based on flexibility include:
- Rigid PCB
- Flexible PCB
- Rigid-Flex PCB
Commonly Used PCB Layout and Design Software
There is no universally accepted printed circuit board design software, and with so many options, beginners can become overwhelmed quickly. We have listed two of the most popular programs below, but there are many more options available.
Professional PCB Design Software
Altium Designer – A well known and highly-regarded PCB design software, Altium is a feature-packed platform with a price tag to match.
Free PCB Design Software for Beginners
KiCad – KiCad is a great choice for beginners. The free, open source software allows you to create PCB layouts and schematics, and even includes a 3D viewer.
Designing the Electronic Schematic
When you are designing your printed circuit board schematic, there are a few basic concepts you should keep in mind, regardless of how complicated your PCB is going to be.
Assembly process from the layout you created
The PCB Assembly Process from the layout you created should be kept in mind when you are fine-tuning your schematic design. From spacing components to how the PCB will be seated within the application, the assembly process is often overlooked. An otherwise perfectly fine PCB design may not work well in a practical sense; you should take the larger picture into consideration.
Disassemble the entire circuit, use your electronic software diagram and perform the assembly.
If you are wondering whether your schematic is fully optimized, one way to double check everything is to disassemble the circuit digitally using your software diagram, and “assemble” it again. You will quickly notice if there are areas where components could be organized better, or if there are parts that are going to cause hot or heavy areas.
Ensure a good organization in the structure of your layout
Once you have the basic components included in your design, it’s time to organize the structure of your layout. Most PCB designers begin this process by grouping similar components, keeping weight distribution, trace length, and heat sinks in mind to optimize the layout of their printed circuit board. It’s normal to experiment with multiple layouts to determine the best possible option.
How to go about designing a PCB Layout
Designing a PCB layout can be complicated, and it’s easy to skip over important steps. Some important aspects to consider when designing your PCB layout are below.
The schematic of your PCB design is the diagram that shows how everything is laid out and connected together. While the layout shows where each component is placed, the schematic also shows how each component is connected together, and how electricity flows throughout the PCB.
High-frequency circuit boards are complicated, densely wired, sophisticated printed circuit boards commonly used in communications, industrial, and medical industries. PCB designers who specialize in high-frequency circuits must be diligent about the layout of their boards, as well as the many special considerations a high-frequency PCB needs.
The Routing of Signal and Placement of Components
How all of the parts of your printed circuit board are routed together and where they are placed affects the heat distribution, weight, performance and longevity of the PCB. It’s important to take care to create a design that uses best practices so that your PCB works correctly, and doesn’t fail prematurely.
A Work of Art and Science
When you are creating your printed circuit board, you are able to infuse your own personal style, creativity and ideas to compliment the science behind your design. Although there are some general guidelines, the most innovative new products and schematics are made by people who incorporate their unique perspective when bringing an idea to life.
When it comes to printed circuit boards, this is just the beginning of your journey. There is a wealth of knowledge available online for free, so you are no longer limited by the barriers of a costly higher education. In the past decade, small volume orders have become not only possible, but affordable, opening up the doors of what used to be an exclusive industry to hobbyists, students, inventors, and entrepreneurs. As the industry continues to rapidly grow and evolve, the possibilities of what you can create are limitless.
We created Gerber Labs to cater to this exciting new market because we love innovation, and we are invested in your success. Our team of engineers and industry professionals is available to answer your questions and ensure that your design is ready for production.