Even though it seems that our new product design advances rather slowly, it’s unlikely to move quicker in the real world. Setting up a business takes time. The previous installment left us with a Bill of Materials (BoM) and a netlist, and so we can now start working on a printed circuit board (PCB) for the project. Or several, as needed. Please note that PCB designing is highly complex and cannot be treated in any depth in this short article. Please refer to [1] for more information on, and suggestions for, PCB design work. One of the first things we did in this article series was creating a mock-up of our future product. With this dummy in mind, we designed the electronic circuitry to put into it, and consequently we only selected components that fit inside and are adapted to the product’s intended working environment. Now we are going to add one or more PCBs to the mix, and they will have to fit as well. Therefore, before you start placing parts and routing traces you should think about the board’s outline and mounting holes, or other ways of keeping the PCB in place inside its enclosure. Often people simply start with a rectangular outline, place the parts as closely to each other as the routing allows, and then shrink the outline to get the smallest board as possible. Next, the board is etched, populated and tested and finally put into the enclosure. It then turns out that there either are no or insufficient mounting holes, or they are not in the right place, and not of the correct diameter. Furthermore, connectors are at the wrong side and cooling is not possible. In short, you created a mechanical nightmare, and the board is up for revision. Most of this could have been avoided if the product’s future enclosure had been on the desk of the PCB designer.
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