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84 DESIGN007 MAGAZINE I SEPTEMBER 2020 criteria, so let's look at that first. Luckily, there are lots of low-cost and free CAD tools avail- able, keeping students and hobbyist designers in the game. When evaluating free tools, though, pay close attention. Some of them will be open-source or community-run projects, and while the philos- ophy behind them might be attractive, make sure those tools are still being actively main- tained. When you run into a problem, you want to make sure you can get help. Some low-cost and free CAD tools are funded and developed by PCB manufactur- ers. They produce tools that specifically work with their manufacturing process, which can be great if you have a specific manufacturer in mind. However, this choice can also lock you into a specific manufacturer path, so choose carefully. If your CAD tool is tied to a manufac- turer, can you get the Gerber files? Do they cost money? Is the price reasonable? Commercial packages can become expensive quickly. There are a few CAD tools available that charge a monthly subscription price, but most offer prices ranging from about $75 all the way up to over $2,000. Pay attention to the limits placed on products with multiple tiers of pricing and be particularly careful not to get caught in a "freemium" trap, where a piece of software seems great until that really important feature is locked behind an expensive paywall. Design Tip: If you have a PCB manufacturer in mind, make sure their process is compatible with your CAD tool before you spend any time or money on it. Component Libraries CAD tools should be customizable with libraries full of parts and components, but you need to be sure that the tool you're looking at can support the parts you need to use. Many tools like to brag about the size of their parts libraries, but don't be fooled by a big number. A typical designer might need a library of about 10,000 parts, but when looking at the library offered by a CAD tool, are you finding the parts you need? Look for commonly used parts and check whether the tool comes with proprietary libraries or access to specialized libraries. No matter the CAD tool, eventually you'll have to create components yourself. Make sure the tool provides the capabilities you need to both create new components and add them from external sources. Complexity CAD tools exist to tackle the complex prob- lem of designing PCBs. Unfortunately, it's inevitable that your CAD tool will itself be somewhat complex, but that doesn't mean you shouldn't evaluate a tool based on how intuitive and easy it is to use. Ease of use is an area where open-source software tends to lag behind. If the price is an important factor in your choice, you may end up looking at a balancing act between price and usability. Help and Documentation There will come a time when something in your PCB project will get too complicated, and you'll end up needing help. You want to make sure that help is available before you put too many hours into a CAD tool, so evaluate these resources early in the process. Check out the tool's documentation. Some tools make Figure 1: Are you finding the parts you need?