Turtles all the way down: Fabbing circuit boards

This brings us right along to designing and fabricating the circuit boards that our bright, shiny new open source chips will plug into. This level of complexity is probably one of the best understood parts of the development process. Arguably electrical engineering has been around since the discovery of electricity, because a circuit of some kind is required to guide an electrical current to do useful work. You could make the case that the wet string that Benjamin Franklin's kite was tied to was one of the first electrical conductors (because the Baghdad battery hypothesis has too many holes in it for my liking (I know, I know, Mythbusters disproved Ben Franklin in the thunderstorm, I need an alusion of some kind to make this work)). The advent of EDA software has accelerated the design process by at least several orders of magnetude compared the days of drafting circuitry on sheets of paper. In recent memory I've experimented with two open source packages, KiCAD and GEDA. These applications can handle even the design of multi-layer circuit boards, but I will warn you that some messing around with them is required to get used to their user interfaces and toolsets. Hypothetically speaking, if you start by loading up the proof of concept circuit schematics in your EDA package of choice you can start the process of manufacturing a mainboard for our hypothetical trusted and open source computer. Many open hardware projects make KiCAD or GEDA files available along with their source code, so it is certainly worth messing around with them to get a feel for things. More experienced engineers no doubt have some ideas for what they want to accomplish, by definition know what they are doing and are probably inclined to get right to work. Rather than attempt to go into detail that I don't understand well enough, I'll leave it as an exercise to the reader (don't you hate it when people say that?) and push on to the topic of circuitry manufacture. Having a set of schematics for a mainboard is all well and good but they have to be fabricated if they're going to be useful. That means transferring, etching and drilling at least one printed circuit board for our trusted and open computing platform. Hobbyists and hackers have been etching their own circuit boards for decades employing a variety of techniques. For example, here's a fairly simple technique that requires chemicals no more exotic than vinegar and hydrogen peroxide, both of which can be acquired from the corner grocery store. There is a more complex technique which involves ferric chloride, isopropyl alcohol, and baking soda, the first reagent of which can be purchased at a well stocked hardware store or Radio Shack. The layout of the circuitry must be transferred onto the copper clad board somehow, and then the copper that isn't part of the circuitry must be removed. There are many ways to accomplish both tasks:

• electroplating
• silk screening
• use a CNC router to cut the extraneous copper from the board

I'll be honest with you, I don't have any first hand experience with working with them, aside from tearing stuff apart that used them once in a while. I've hung out at HacDC when folks were doing it and I've read about it. It also seems feasible that flexible circuits could be used in this project instead of rigid plastic, metal, or fibreglass boards. They're certainly more lightweight than copper-clad boards. There is a highly rated tutorial on how one may make their own flexible circuit boards that may or may not be of interest in the context of this discussion. There are flexible circuit construction kits available on the open market (much to my surprise). It is also possible to cut and lay out your own flexible circuit boards if one has access to a vinyl cutter. If your friendly neighborhood hackerspace or workplace has a las