Ask Hackaday: Are Conductive Inks Going to Make It?

It’s amazing how affordable PCB fabrication has become. It has long been economical (although not always simple) to fabricate your own singe and double-sided boards at home, the access to professional fabrication is becoming universal. The drive continues downward for both cost and turnaround time. But there is growing interest in the non-traditional.

Over the last year we’ve seen a huge push for conductive-ink-based PCB techniques. These target small-run prototyping and utilize metals (usually silver) suspended in fluid (think glue) to draw traces rather than etching the traces out of a single thin layer of copper. Our question: do you think conductive in will become a viable prototyping option?

Voltera V-One Circuit Board Prototyping Machine

I recorded this interview at 2015 CES but was asked not to publish it until their crowd funding campaign went live. If you haven’t been paying attention, Voltera is at almost 400% of their $70k goal with 26 days remaining. This printer definitely works. You can print circuits, solder components or reflow them, and there’s even a second non-conductive ink that can be used to insulate between traces when they cross over one another. In the video [Alroy] suggests Voltera for small production runs of 10-20 boards. Would you see yourself using this for 10-20 boards?

Personally, I think I could solder point-to-point prototypes in less time. Consider this: the V-One will print your traces but you still must solder on the components yourself. If the board design reaches a high level of complexity, that timing may change, but how does the increased resistance of the ink compared to copper traces affect the viability of a board? I assume that something too complex to solder point-to-point would be delving into high-frequency communications (think parallel bus for LCD displays, etc.). Is my assumption correct? Do you think conductive ink will get to the point that this is both viable and desirable over etching your own prototypes and how long before we get there?

Now, I certainly do see some perfect use-cases for Voltera. For instance, introduction to circuit design classes. If you had one of these printers at the middle school or high school level it would jump-start interest in electronics engineering. Without the need for keeping chemical baths like Cuperic Chloride or Ferric Chloride on hand, you could walk students through simple board design and population, with the final product to take home with them. That’s a vision I can definitely get behind and one that I think will unlock the next generation of hardware hackers.

Correction: [Arachnidster] pointed out in the comments that Voltera is still working on being able to reflow boards printed by the V-One. On their Kickstarter page they mention: “(Reflow onto Voltera printed boards is currently under development)”

Circuit Plotting With An HP Plotter

Over the last few years we’ve seen a few commercial products that aim to put an entire PCB fab line on a desktop. As audacious as that sounds, there were a few booths showing off just that at CES last week, with one getting a $50k check from some blog. [Connor] and [Feiran] decided to do the hacker version of a PCB printer: an old HP plotter converted to modern hardware with a web interface with a conductive ink pen.

The plotter in question is a 1983 HP HIPLOT DMP-29 that was, like all old HP gear, a masterpiece of science and engineering. These electronics were discarded (preserved may be a better word) and replaced with modern hardware. The old servo motors ran at about 1.5A each, and a standard H-Bridge chip and beefy lab power supply these motors were the only part of the original plotter that were reused. For accurate positioning, a few 10-turn pots were duct taped to the motor shafts and fed into the ATMega1284p used for controlling the whole thing.

One of the more interesting aspects of the build is the web interface. This is a small JavaScript app that is capable of drawing lines on the X and Y axes and sends the resulting coordinates from a server to the printer. It’s very cool, but not as cool as the [Connor] and [Feiran]’s end goal: using existing Gerber files to draw some traces. They’re successfully parsing Gerber files, throwing out all the superfluous commands (drills, etc), and plotting them in conductive ink.

The final iteration of hardware wasn’t exactly what [Connor] and [Feiran] had in mind, but that’s mostly an issue with the terrible conductivity of the conductive ink. They’ve tried to fix this by running the pen over each line five times, but that introduces some backlash. This is the final project for an electrical engineering class, so we’re going to say that’s alright.

Video below.

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Circuit printers: Voltera and Voxel8

There are two printers being shown off at the 2015 Consumer Electronics shows which really spark our interest. They are the Voltera and the Voxel8. Each is taking on the challenge of printing circuits. They use similar techniques but approach the problem in very different ways.

Voxel8

The Voxel8 marries the idea of a 3D printer with a silver conductive ink dispenser. You start by modeling your entire design, hardware and electronics, all in one. The printer will then begin the 3D print, pausing when necessary for you to add electronics and mechanicals. With the parts — and their pins — in place it lays out the conductive ink to connect the components and then continues with the 3D printing to finish the object.

Voltera

The Voltera is a PCB printer that uses silver conductive ink. It prints the ink onto a substrate. Pads made of the ink are used to solder the components in place after the printing is finished. The trick added to this design is the ability to print two layers, both on the same side of the board. There is a second ink material which is an insulator. It is laid over the first conductive layer before the second is printed, allowing traces to cross over each other.

Congratulations to the Voltera team who won $50k from the 2015 Hardware Battlefield at CES.

Our Thoughts

We didn’t see enough to shake our skepticism about the viability of silver conductive ink to take the place of copper on prototype boards. But if anyone is going to make the case that it is plausible these two offerings will.

One interesting thing about the Voxel8 is the ability to specify point-to-point wiring as a “part”. If you do so, the machine will pause while you solder the wires in place before it encapsulates them with the rest of the print. Of course if you’re going to do this manually it shouldn’t really matter which printer you use for it.

What do think about the future of conductive ink for prototyping? Lets us know in the comments.

Fail of the Week: Transparent Circuit Design is Clearly a Challenge

[Frank Zhao] wanted to try his hand at making a transparent circuit board. His plan was to etch the paths with a laser cutter and fill in the troughs with conductive ink. The grooves are ~0.1mm deep x ~0.8mm wide.

He used nickel ink, which is slightly cheaper than silver ink. The ink was among the least of his problems, though. At a measured resistance of several hundred ohms per inch, it was already a deal breaker since his circuit can’t function with a voltage drop above 0.3V. To make matters worse, the valleys are rough due to the motion of the laser cutter and don’t play well with the push-to-dispense nature of the pen’s tip. This caused some overflow that he couldn’t deal with elegantly since the ink also happens to melt acrylic.

[Frank] is going to have another go at it with copper foil and wider tracks. Do you think he would have fared better with silver ink and a different delivery method, like a transfer pipette? How about deeper grooves?


2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.

DIY Conductive Paint For All Your Wearable Needs

DIY Conductive Paint

Conductive ink or paint is lots of fun. It opens up tons of possibilities for flexible and unique circuits — unfortunately, it’s pretty expensive. [Brian McEvoy] shows us how to make your own for cheap, and it works great!

He started trying to formulate his own recipe after playing with other Instructable guides and commercially available paint, and what he found is it’s really not that complex! Graphite powder, acrylic paint, and a jar with an airtight seal — seriously, it’s that simple! But, like any engineer worth their salt (he calls himself the 24 Hour Engineer), he had to do some tests to compare his formula.

In a detailed experiment he compares his formula to the commercially available Wire Glue, and two other recipes using Elmer’s Glue-All and graphite, and Titebond III with graphite. The results? Acrylic paint and graphite produce the most conductive material — and the cheapest!

Now that you can make conductive ink, why not 3D print a circuit stamp to make your very own SMD circuit board!

CartoLucci: A Candle-Powered Christmas Card

cartoLucci

If you’re looking for a last-minute Christmas present, you probably won’t have enough time to reproduce [Helmar’s] candle-powered Christmas card. He’s been working on it for a few years now, since his first prototype in 2010. Though he pieced together the original card with parts lying around his workshop, the most recent iteration looks like it belongs on the shelf in a store.

We last saw [Helmar’s] work two years ago, when he shared his Full Color Laser TV. This project is a bit more compact: the circuitry was printed with conductive ink on the cardstock, and all the required components are held together by conductive adhesive. To power the electronics, he decided against a battery and instead chose to embed a solar cell on the inside of the card. Placing a lit candle inside the open card provides enough juice for the exterior of the card to shine.

You can see a video of both the current and prototype versions of [Helmar’s] cards after the break.

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3D printed circuit boards using conductive ink

The thought of using a 3D printer to fabricate PCBs is tantalizing and the good news is that it’s a reality. This project shows that it’s possible to use a special printer head to apply traces to an extruded substrate.

This is similar to the point-to-point 3D printer circuits with one big upgrade. Now the traces can be printed directly onto the ABS using conductive ink. The process starts with the design files, which are used to model a substrate that has a trench for each trace. A Makerbot then prints out this model. Once complete, the ABS extruder head is swapped for a special ink head. Each trace is then filled with the conductive fluid, which is kept in place by the trench walls until it can dry. We think this improves on the trace printing techniques we’ve seen before because it doesn’t require your printer heat to use molten metals.

The circuit above uses printed traces for the high and low side of an LED circuit. It’s a bit rough at the edges, but it shows a lot of promise. Don’t miss the demo video embedded after the jump.

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