PCB DESIGN PACKAGES How to choose the right printed circuit board design package
Many PCB design software packages are available, ranging from software that can be downloaded for free to high end tool suites costing tens of thousands of dollars. But which is best for your application? This article first looks at what is involved in PCB design, and then suggests some approaches you could use to find the right package for your project.
Any electronic product contains one or more printed circuit boards (PCBs) populated with the components needed to achieve its functionality. The PCB provides mounting and electrical interconnections for the components; it may also provide EMC shielding and thermal conduction paths for heat management.
The most basic PCBs have components and their interconnections – or ‘conductor pattern’ - mounted on one side of the board. These are known as ‘single-sided’ or ‘single-layer’ types. Because of their limited routing possibilities, they are only suitable for simple circuits. Most PCBs are at least double-sided, or more likely multilayer, with possibly many tens of layers. This is essential to cope with the ever more complex and densely packed component populations needed for today’s smaller yet more powerful products.
Converting your theoretical or prototype design into a manufactured PCB is a multistep process that can be performed with the help of a PCB design software package. Many different packages are available, for a very wide range of project sizes and complexities. Options vary from open-source products that can be downloaded for free, to high-end tool suites costing multiple thousands of dollars. Note that a higher price does not always guarantee a better product!
Basic PCB design steps
Irrespective of their size and feature set, all PCB software packages must accomplish a core set of tasks to convert a design concept into a production PCB. Below, we look at these steps – and then discuss some ways in which you might identify your ideal solution.
According to an online tutorial, the first step is to create a schematic of your required circuit. The schematic will serve as a blueprint for laying out the traces and placing the components on the PCB. Plus, PCB editing software can import all of the components, footprints, and wires into the PCB file, which will make the design process easier.
The next task is to draw the schematic. Begin by placing your schematic symbols for components onto this drawing. Schematic symbols are typically located in “Libraries”. These can comprise common symbols, but there can also be “User Generated Libraries” with many other symbols. Each symbol has a footprint associated with it. This defines the component’s physical dimensions and placement of the copper pads or through holes, and it can be changed if necessary.
After choosing the correct footprint, assign it to the symbol on the schematic. You can then draw in the wiring, and label the symbols with their names and values – for example, R1, 10kΩ. These will be printed onto the finished PCB.
The next stage involves PCB design optimization. It is important to keep conductive traces short, to minimize susceptibility to electrical interference and noise. Also, ensure that all parts of the circuit receive adequate voltage levels, without suffering from onboard I2R losses. Other decisions relate to the number of PCB layers, ground layers, layer thickness, and PCB trace (interconnection) design and width.
Now the schematic can be opened in a PCB Editor, to be converted into a PCB layout. You can draw traces between the components manually, or use auto-routing software to do so. You also need to define the size and shape of the PCB outline.
The PCB layout should then be subjected to a Design Rule Check (DRC), to check issues such as if any components overlap or if traces are routed too close together. Any problems identified by DRC will be highlighted in the PCB view, so that they can be spotted and rectified.
At this point, if you have been using a suitable package, you can send the supplier your layout, allowing them to manufacture your PCBs. Alternatively, if you want to give your PCB layout to a third-party manufacturer for production, you can usually do so by generating a set of Gerber files. Gerber files are open ASCII vector format files that contain information on each physical board layer of your PCB design. Circuit board objects, like copper traces, vias, pads, solder mask and silkscreen images, are all represented by a flash or draw code, and defined by a series of vector coordinates. These files are used by PCB manufacturers to translate the details of your design into the physical properties of the PCB.
Which are the best PCB design software packages?
Deciding which PCB design software package is best depends very much on your personal perspective: the complexity and size of your project, your budget, your expertise, and whether you are working alone or as part of a team are all factors. There are many packages available, and a large number of reviews available online to compare them. One approach would be to check several such reviews, and spot which packages appear near the top consistently. These would be candidates for further investigation, to see which would best fit your particular requirements.
Here are a few examples of high rated PCB design software packages:
Autodesk Easily Applicable Graphical Layout Editor, or EAGLE, are often considered as number one. EAGLE has the advantage of being one of the PCB design software heavyweights. At a reasonable annual cost, it has a significant community that puts tutorials online. It also has an extensive component library and runs in a Mac OS X or Linux environment. It is available in three versions: Free, Standard, and Premium. However, its graphic interface is considered by some as complex and not user-friendly.
Altium Designer is another popular package. With a licence starting price at several thousand dollars, the Altium software suite is especially suited for electronics engineers working for major industrial groups or on the Internet of Things. It is also extensively used by universities and leading schools. On the down side, it requires a long learning phase that will discourage DIY PCB fans.
KiCAD EDA comes top in one survey, and appears frequently in others. It is a free, open source PCB design software suite, yet compares well with paid-for packages. According to several reviews, the tool is even for beginners easy to use.
Another tool that appears regularly, if not always quite so high in the ratings, is EasyEDA. The package is free and runs online. This means that users always have access to the latest version, and can sign in from any location. EasyEDA is valued for its user-friendliness and simplicity, and support of a direct PCB ordering service as well as other features. While having comprehensive data and collaboration tools, it is designed for development of low to medium complexity electronic devices. It has been regarded as unsuitable for complex tasks.
Yet another view is offered by an article, which names Altium, Eagle and OrCad as the three PCB design packages that tend to be most popular and considered the best. However, it is argued that, due to pricing and complexity issues, none of these packages are ideal for entrepreneurs and freelance designers. Such users, the article suggests, would do better to use a lower cost and scalable package called DipTrace.
This simply highlights the point that the choice of PCB design software is highly subjective – your ideal choice depends very much on your particular circumstances and the type of project you are involved with.