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Connect the Dots: Picking a Prototyping Strategy

No matter how simple or complicated your electronic project, PCB prototyping is part of its journey from concept to reality. This process of turning the design into something physical can teach you a lot about what needs to be tweaked and improved before your PCB is ready for full production. There are a few different approaches, ranging from various DIY options to commercial prototype fabrication.

But before you can prototype, you have to design.

PCB design and initial testing usually happen with CAD tools and circuit simulator software. These tend to target high-speed, high-frequency, mixed signals, and even RF designs. However, a lot of these software packages have a big price tag that can be prohibitive for a part-time designer or hobbyist hoping to take advantage of their testing features. Fear not. There are still cost-effective approaches to prototyping available. 

Since no two projects are the same, your approach to prototyping should be flexible. Your needs will be different every time. Are you going for fast-and-dirty prototyping? Do you need a quick turnaround time? Will it be easier for you to use a DIY prototyping technique? 

Iterative Prototyping
Prototyping often takes multiple iterations. Your first design and your first PCB may not work. With iterative prototyping, you lay out your physical components to make sure your design actually does what you want. If it doesn’t work, you make adjustments and try again. You will use actual ICs and components and try various designs until a prototype finally works. This working prototype will then be copied back into your CAD software. 

Today, most small projects start off with something like an Arduino, a handful of components and jumper wires, and a solderless breadboard. The resulting rat’s nest can be difficult to turn into a PCB design, however, which is why you will want to quickly move to something closer to a finished PCB (Figure 1).

Pro Tip
Note that solderless breadboards are great because you can easily reuse components. However, once you move to prototyping with other techniques, it’s likely that your components will be permanently attached to boards that don’t work. This can get expensive, so you will need to plan ahead carefully.

Doing It Yourself
Solderable prototyping boards are perfect for your early DIY prototype. They come in both set form factors and perforated sheets that allow you to pick a custom size for your prototype board. You can find good walkthroughs for planning IC and component layout for your first prototype using a blank board and Kynar wire ^[1]. 

If you’re in the mood for really taking your DIY prototype to the next level, you can always try making your own PCB at home ^[2]. This requires getting a blank PCB, special transfer paper, etching chemicals, a power drill, and a lot of patience and careful work. You can also create your own PCB at home with a CNC mill, which allows you to skip the chemical etching step. 

Pro Tip
If you do decide to make your PCB at home, just be careful with the chemicals. They require special handling and disposal, meaning you can’t just pour them down the drain and hope they don’t eat a hole in your pipes. You’ll end up subject to massive fines and find yourself in desperate need of a plumber (Figure 2).

Fabricated PCB Prototypes
When your design has progressed far enough, it’s time to turn your design into a professionally fabricated PCB. When preparing your design for printing, you will need to understand that every manufacturer has different capabilities, requirements, and turnaround time. You’ll need to take all of these into account to manage your project efficiently. 

If you already have your manufacturer figured out, keep all of this in mind from the very beginning of the design process. You don’t want to get to the fabrication stage of prototyping and realize at the last minute you’ve overstepped your manufacturer’s limitations. 

Picking the Right Partner or Service
If your project is complex, especially if it’s a brand new design, you will want to consider expert help. It makes sense to leverage such help with layout review. 

Rapid prototyping fabrication services can help shorten the turnaround on complicated designs, which saves money during production while helping you stay on schedule. However, just because you can get boards quickly from a manufacturer doesn’t mean you always should.  

Look for manufacturing partners that can provide detailed, comprehensive feedback on your PCB design before your prototypes are fabricated. This will reveal yield or reliability issues with your design, improve the integrity of your production schedule, and ultimately improve the quality of the boards. The manufacturer will also be able to tell you if your design fits within their capabilities and limitations, saving endless prototyping headaches later. 

Some PCB manufacturers offer multiple prototyping services. For example, we offer our ValueProto service through custom PCB manufacturing with access to experts, as well as a free DFM check with an online custom report for each job. 

Conclusion
Prototyping is a necessary step on the road to production, so it’s important to pick the right strategy for your project. An approach that works for one board may not be right for the next, and it will take time and experience to know which strategy is the best fit for each case. Be flexible in your approach to prototyping options. Whether you choose to etch your own prototypes in your garage or engage professional experts from your PCB manufacturer, remember to plan ahead and don’t get discouraged if one prototype is not enough.

Further Reading 

1. M.B. LeBlanc, “How to Prototype Without Using Printed Circuits Boards,” Instructables Circuits. 

2. O.N. Dahl, “DIY PCB: How to Create Your Own Printed Circuit Boards,” Build Electronic Circuits.

This column originally appeared in the May 2020 issue of Design007 Magazine.