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EETE SEP 2014

“Desktop PCB factory” turns a design into a working circuit in 30 minutes By Lee Goldberg What would you do if you could turn the schematic you sketched on the back of a napkin during your lunch break into a fully-assembled circuit before your afternoon coffee break? What would you do if you could print a circuit which monitored your vital signs onto a flexible circuit board which could be easily sewn into your workout clothes? These, and many other “what-if?” scenarios may be answered by Squink, a $3000 “screen-to-machine” desktop electronics factory, after it completes its recently-launched crowdfunding campaign on Kickstarter. BotFactory, the team which created Squink, is based in Brooklyn, New York, the fashionably grungy appendix of Manhattan which birthed avant-tech startups like Adafruit Labs and MakerBot. The prototype they’ve built has already demonstrated how many of the same technologies commonly used in 3D printers can be adapted to print a circuit on a variety of materials, populate it with ICs and other components, and “solder” them in place with conductive adhesives. Next; 3D printing shows the way... BotFactory’s Squink - a desktop PCB factory One glance at Squink is all it takes to see how much of its innards From back-of-napkin sketch to operational PCB in an afternoon! have been cleverly adapted from the 3D printer world. This is a good thing since it means that most of the design can take advantage of the low-cost, high-quality standard components and vast amounts of open-source IP which resulted from nearly a decade’s worth of 3D printer development. In addition to increasing the design’s reliability and manufacturability, I’m sure that using proven Maker technologies played a big role in allowing BotFactory to offer Squink units for $3500-$3999 during its Kickstarter drive. Both of Squink’s X-Y stages use a ball screw drive system favoured by many 3D printers, with the element which would normally hold the print head moving along one axis, and the platform which holds the circuit board along the other. The tool head also moves in the Z direction. Instead of a 3D printer’s print head, Squink has a tool holder which can accept three interchangeable heads. As shown in the video above, the first head deposits the conductive ink on the circuit board material, guides by either GERBER RS-274X files or uploaded PNG, JPG Look Ma, no solder! Squink attaches components to the PCB using conductive adhesive. Squink can print and populate circuit boards using a variety of flexible and inflexible materials. or BMP files. Once the conductors are laid, the conductive ink cartridge is swapped out for a conductive glue dispenser. Squink can use a standard soldermask file, typically generated by your CAD tool, to place dots of conductive adhesive at every place where a part will need to be connected. The third head is a vacuum pick-up assembly which can be used to select a component from a holding tray and place it on the proper set of adhesive-primed contacts. If desired, the adhesive can be quickly set with an optional 15-minute heat-curing cycle. Next; capabilities and costs... The machine being offered on Kickstarter can fabricate printed circuits up to 25x25cm. It’s estimated that it will take Squink about 30 minutes to print a 10 x 10-cm PCB and place 15 components on it. At present Squink’s conductive ink allows it to print circuits on Photopaper or coated transparency film. BotFactory estimates that the combined cost of ink and circuit material for a 10 x 10-cm board will be about $5. They also say that advanced inks are in development which will allow circuits to be laid down on some types of paper, as well as glass, plastic, FR4, and other non-porous materials. As exciting as it is, Squink is not perfect. BotFactory admits that its first-generation machine doesn’t do everything that commercial equipment can, including the fact that automatic placing of through-hole components is not presently supported. From what I observed, it also can’t support multi-layer PCB designs, and I don’t think its 10mil (0.25mm) line width and pitch are fine enough to produce the tiny traces needed to connect some popular high-density IC packages. I also suspect that it might be difficult to produce circuits capable of handling the signals of high-frequency applications. Then again, the printer’s ability to lay down a circuit on ceramics or other low-capacitance substrates may allow it to support applications operating at 1 GHz or higher. But regardless of its limitations, the boards it can produce should be perfectly fine for many consumer and commercial applications and eliminate the cost of short production runs at contract assembly houses or the purchase of $25k-$100k worth of SMT assembly equipment. Squink’s extensive use of proven hardware and existing standards can really deliver on most of its promises, its arrival has the potential to change the way Makers and corporate engineers alike build their prototypes and low-volume/custom products. I suspect that anyone who’s had to pay fabricators a fortune for the privilege of getting a one-off circuit board built up in “only a week” would agree. 6 Electronic Engineering Times Europe September 2014 www.electronics-eetimes.com


EETE SEP 2014
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