Connecting the Dots

We often forget just how good we have it, so let me remind you just how spoiled us makers are today. Compared to just a decade or two ago, the accessibility of technology to hobbyists has improved dramatically. Today we have an incredible array of affordable, cutting-edge technologies at our fingertips. 3D printers, which were once the stuff of science fiction, are now ubiquitous and relatively inexpensive, allowing custom parts to be manufactured at home. Microcontrollers and single-board computers, like the Arduino and Raspberry Pi, have democratized access to embedded systems and IoT development platforms. Even professional-grade test equipment, such as oscilloscopes and logic analyzers, has become remarkably affordable.

These advances extend to printed circuit boards (PCBs), but not in quite the same way. Yes, for a few bucks you can send your design files to a manufacturer and have the board show up at your house in a matter of weeks. This is a huge step forward from when it was so expensive and complex a process that it was out of reach for most people. But waiting a few weeks is a pretty big hurdle when you are trying to iterate on a design. And finding even a small mistake becomes a big deal when you have to wait weeks for a fix. If only we could produce production-quality PCBs at home in the same way that we 3D print parts…

This is the dream of many makers, including Levi Janssen, who decided to try to make it a reality. Janssen set out to make a 3D printer-like desktop PCB fabricator that is simple enough to use at home. Naturally you have to put some constraints on a project like this to keep it feasible, so he decided to limit the machine to producing 2-layer boards with traces and vias — no larger stacks of layers or solder mask, silkscreening, or anything else that is technically not necessary for a basic PCB.

Cutting some traces in a PCB is not too terribly challenging, and has been done by a number of other hobbyists in the past, but vias are a whole different beast entirely. These are the tiny components that electrically connect points on one layer of a PCB with another layer. The standard way of doing this is by drilling a hole in the board, using an electroless copper deposition process to lay down a thin base of copper, before finally electroplating this base to build it up and reduce electrical resistance between layers.

But this process requires a dozen toxic and corrosive chemicals, so it is not exactly friendly for home use. Janssen came up with an alternative plan that replaces the electroless copper deposition process with the application of a conductive ink, which is then electroplated to complete the via. Initial manual tests worked great, with resistance levels comparable to production processes being observed.

After seeing this great initial result, Janssen built a prototype with a base of aluminum extrusions, a pair of custom tool heads with x- and y-axis control, and microfluidic pumps to control the flow of liquids for electroplating. This build was fraught with difficulties, and required a complete rebuild from scratch at one point. But ultimately, after lots of revisions, Janssen was able to successfully create a via using the machine. The resistance levels were even acceptably low.

Unfortunately, there is a big caveat. This result was only achieved when creating 1 mm vias, which are way too large to be practical. A typical via is only 0.3 mm, and when Janssen attempted to use the same processes at this scale, no amount of tweaking could make it work.

While things are not up to snuff at this point, Janssen is still working on the problem. He has some ideas that — if they work — have the potential to outperform existing production processes. Be sure to stay tuned to see where this project goes. I, for one, would love to have a desktop PCB fabricator in my home lab!