Prototyping PCBs with Electrical Discharge Machining

Here at Hackaday, we thought we’d seen every method of making PCBs: CNC machining, masking and etching with a variety of chemicals, laser engraving, or even the crude but effective method of scratching away the copper with a utility knife. Whatever works is fine with us, really, but there still does seem to be room for improvement in the DIY PCB field. To whit, we present rapid PCB prototyping with electrical discharge machining.

Using an electric arc to selectively ablate the copper cladding on a PCB seems like a great idea. At least that’s how it seemed to [Jake Wachlin] when he realized that the old trick of cutting a sheet of aluminum foil using a nine-volt battery and a pencil lead is really just a form of EDM, and that the layer of copper on a PCB is not a million miles different from foil. A few experiments with a bench power supply and a mechanical pencil lead showed that it’s relatively easy to blast the copper from a blank board, so [Jake] took the next logical step and rigged up an old 3D-printer to move the tool. The video below shows the setup and some early tests; it’s not perfect by a long shot, but it has a lot of promise. If he can control the arc better, this homebrew EDM looks like it could very rapidly produce prototype boards.

[Jake] posted this project in its current state in the hopes of stimulating a discussion and further experimentation. That’s commendable, and we’d really love to see this one move along rapidly. You might start your brainstorming by looking at this somewhat sketchy mains-powered EDM, or look into the whole field in a little more detail.

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LEDs Shine Through PCB On This Tiny Word Clock

Everyone seems to love word clocks. Maybe it’s the mystery of a blank surface lighting up to piece together the time in fuzzy format, or maybe it hearkens back to those “find-a-word” puzzles that idled away many an hour. Whatever it is, we see a lot of word clock builds, but there’s something especially about this diminutive PCB word clock that we find irresistible.

Like all fun projects, [sjm4306] found himself going through quite the design process with this one. The basic idea – using a PCB as the mask for the character array – is pretty clever. We’ve always found the laser-cut masks to be wanting, particularly in the characters with so-called counters, those enclosed spaces such as those in a capital A or Q that would be removed by a laser cutter. The character mask PCB [sjm4306] designed uses both the copper and a black solder mask to form the letters, which when lit by the array of SMD LEDs behind it glow a pleasing blue-green color against a dark background. Try as he might, though, the light from adjacent cells bled through, so he printed a stand that incorporates baffles for each LED. The clock looks great and even has some value-added modes, such as a falling characters display a la The Matrix, a Pong-like mode, and something that looks a bit like Tetris. Check out the video below for more details.

We’ve seen word clocks run afoul of the counter problem before, some that solved it by resorting to a stencil font, others that didn’t. We’re impressed by this solution, though, enough so that we hope [sjm4306] makes the PCB files available so we can build one.

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Put that DLP Printer to Use Making PCBs

Now that these DLP printers are cheaper and more widely available, we’re starting to see hackers poking around the edge of the envelope to see what else the machines are capable of. [Electronoobs] recently got his hands on a couple of these printers, and thought he would do some experiments with using them for PCB production.

Rather than extruding molten plastic, these printers use light to cure resin layer-by-layer. In theory if the printer is good enough to cure the light-activated resin for a high resolution print, it should be able to do much the same thing with photosensitive PCBs.

Unfortunately, getting an STL out of a PCB design program takes a few intermediary steps. In the video after the break, [Electronoobs] shows his workflow that takes his design from EasyADA and turning it into a three dimensional object the DLP printer will understand. He does this with Blender and it looks pretty straightforward, but in the past we’ve seen people do similar tricks with Inkscape if that’s more your style.

Once you’ve grafted another dimension onto your PCB design, you may need to scale it to the appropriate size. [Electronoobs] notes that his STL for a 60 mm wide PCB came out of Blender as less than 2 mm wide, so you might need to break out the dreaded mathematics to find the appropriate scale value. Once the dimensions look good, you can load this file up into the printer as you would any normal print.

On the printer side of things, [Electronoobs] manually laminates UV photoresist film onto some copper clad boards with an iron, but you could skip this step and buy pre-sensitized boards as well. In any event, you drop the board where the UV resin normally goes, press the print button, and wait about ten minutes. That should give it enough time to expose the board, and you then proceed with the normal washing and acid bath process that hackers have been doing since time immemorial.

As [Electronoobs] shows, the results are quite impressive. While this still won’t make it any easier for you to do double-sided PCBs in the home lab, it looks like a very compelling method for producing even SMD boards with relative ease. This isn’t the first time somebody has tried using a DLP printer to run off some PCBs, but now that the technology has matured a bit it looks like it’s finally becoming practical.

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From Zero to Nano

Have you ever wanted to build your own Arduino from scratch? [Pratik Makwana] shares the entire process of designing, building and flashing an Arduino Nano clone. This is not an entry-level project and requires some knowledge of soldering to succeed with such small components, but it is highly rewarding to make. Although it’s a cheap build, it’s probably cheaper to just buy a Nano. That’s not the point.

The goal here and the interesting part of the project is that you can follow the entire process of making the board. You can use the knowledge to design your own board, your own variant or even a completely different project.

from-zero-to-nano-thumb[Pratik Makwana] starts by showing how to design the circuit schematic diagram in an EDA tool (Eagle) and the corresponding PCB layout design. He then uses the toner transfer method and a laminator to imprint the circuit into the copper board for later etching and drilling. The challenging soldering process is not detailed, if you need some help soldering SMD sized components we covered some different processes before, from a toaster oven to a drag soldering process with Kapton tape.

Last but not least, the bootloader firmware. This was done using an Arduino UNO working as master and the newly created the Arduino Nano clone as target. After that you’re set to go. To run an actual sketch, just use your standard USB to UART converter to burn it and proceed as usual.

Voilá, from zero to Nano:

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No-Etch Circuit Board Printing

If you’ve ever tried to build a printed circuit board from home, you know how much of a pain it can be. There are buckets of acid to lug around, lots of waiting and frustration, and often times the quality of the circuits that can be made traditionally with a home setup isn’t that great in the end. Luckily, [Rich] has come up with a way that eliminates multiple prints and the acid needed for etching.

His process involves using a laser printer (as opposed to an inkjet printer, as is tradition) to get a layer of silver adhesive to stick to a piece of paper. The silver adheres to the toner like glitter sticks to Elmer’s glue, and allows a single pass of a laser printer to make a reliable circuit. From there, the paper can be fastened to something more solid, and components can be reflow soldered to it.

[Rich] does post several warnings about this method though. The silver is likely not healthy, so avoid contact with it, and when it’s applied to the toner an indeterminate brown smoke is released, which is also likely not healthy. Warnings aside, though, this is a great method for making home-made PCBs, especially if you don’t want tubs of acid lying around the house, however useful.

Thanks to [Chris] for the tip!

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Etching Your Own Metal

It’s been said that with enough soap, one could blow up just about anything. A more modern interpretation of this thought is that with enough knowledge of chemistry, anything is possible. To that end, [Peter] has certainly been doing a good job of putting his knowledge to good use. He recently worked out a relatively inexpensive and easy way to etch metals using some chemistry skill and a little bit of electricity.

After preparing a set of stencils and cleaning the metal work surface, [Peter] sets his work piece in a salt solution. A metal bar is inserted in the other end of the bath, and both it and the work piece are connected to electrodes. The flow of electricity removes some metal from the exposed work surfaces, producing whatever patterns [Peter] wants.

One interesting thing that [Peter] found is that the voltage must stay under 6 volts. This is probably part of the reason it’s relatively easy to etch with even a wall wort. Above that, the iron work piece produces a different ion which can clog the work surface and create undesirable effects. Additionally, since his first experiments with this process he has upgraded the salt bath with magnetic stirrers. He also gets the best results in a very cold environment.

There are many other uses for etching metals, too. Creating your own printed circuit boards comes to mind, but there are plenty of other uses as well. What will you do with this technique?

Take Your PCBs from Good to Great: Toner Transfer

One-offs that I never would have gotten professionally made, but that were infinitely handy during development

A lot of us make circuit boards at home. I find it a useful skill to have in my bag of tricks for intermediate steps along the way to a finished project, even if the finished version is going to be sent out to a PCB fab. When I need a breakout board that meshes with other development tools, for instance, there’s nothing like being able to whip something up that plugs right in. Doing it quickly, and getting on with the rest of the project instead of placing an order and waiting for delivery, helps keep me in the flow.

Toner transfer is by far the fastest way to make a circuit board at home — simply print the circuit out on a laser printer, iron it onto the copper, and etch. When it works, it’s awesome. When it doesn’t, it can be a hair-pulling exercise in figuring out which of myriad factors are misaligned.

For a long time now, I’ve been using a method that’s very reliable and repeatable. Recently, I’ve been tweaking a bit on the performance of the system, and I thought I’d share what I’ve got. At the moment, I’m able to very reliably produce boards with 6 mil (0.15 mm) traces and 8 mil (0.20 mm) spacing. With a little care in post-production, 4 mil / 6 mil is entirely plausible.

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