We are going to great lengths to turn a quick idea into an electronic prototype, be it PCB milling, home etching or manufacturing services that ship PCBs around the world. Unwilling to accept the complications of PCB fabrication, computer science student [Varun Perumal Chadalavada] came up with an express solution for PCB prototyping: Printem – a Polaroid-like film for instant-PCBs.
You can find flex PCBs in just about every single piece of consumer electronics. These traces of copper laminated in sheets of Kapton are everywhere, and designing these cables, let alone manufacturing them, is a dark art for the garage electronics wizard. Having these flat flex cables and PCBs manufactured still requires some Google-fu or a contact at a fab house, but at least now designing these cables is a solved problem.
[Oli] needed a way to connect two PCBs together over a moving part. Usually this means some sort of connector or cable, but he’s developed an even better solution – flexible PCB connections. To generate these copper traces sandwiched between a few layers of Kapton, [Oli] wrote a Python script to take a set of parameters, and produces an design for Eagle that includes all the relevant bits.
Of course, with a flexible PCB layout, the question of how to get these manufactured comes up. we’ve seen a few creative people make flexible PCBs with a 3D printer and there’s been more than one Hackaday Prize project using these flex PCBs. [Oli] says any manufacturer of flexible circuits should be able to reproduce everything generated from his script without much thinking at all. All we need now is for OSH Park to invent purple Kapton.
You can grab [Oli]’s script on his GitHub.
Still working with PCBs in 2D? Not [Yoav]. With some clever twists on the way we fab PCBs, he’s managed to create a state-aware foldable circuit board that responds to different configurations.
From his paper [PDF warning], [Yoav] discusses two techniques for developing foldable circuits that may be used repeatedly. The first method involves printing the circuit onto a flexible circuit board material and then bound front-and-back between two sheets of acrylic. Valid folded edges are distinguished by the edges of individual acrylic pieces. The second method involves laying out circuits manually via conductive copper tape and then exposing pads to determine an open or closed state.
Reconfigurable foldable objects may open the door for many creative avenues; in the video (after the break), [Yoav] demonstrates the project’s state-awareness with a simple onscreen rendering that echoes its physical counterpart.
While these circuits are fabbed from a custom solution, not FR1 or FR4, don’t let that note hold your imagination back. In fact, If you’re interested with using PCB FR4 as a structural element, check out [Voja’s] comprehensive guide on the subject.
The last few years have seen great strides in budget printed circuit board manufacturing. These days you can have boards made in a week for only a few dollars a square inch. Flexible PCBs still tend to be rather expensive though. [Mikey77] is changing that by making flex circuits at home with his 3D printer. [Mikey77] utilized one of the properties of Ninjaflex Thermoplastic Elastomer (TPE) filament – it sticks to bare copper!
The TPE filament acts as an etch resist, similar to methods using laser printer toner. For a substrate, [Mikey77] lists 3 options:
.004″ thick “Scissor cut” copper clad board from Electronics Goldmine
.002″ thick pure copper polyester taffeta fabric from lessEMF.com
<.001″ Pyralux material from Adafruit, which is one of the materials used to make professional flex PCBs.
A bit of spray adhesive will hold the Flex PCB down on the printer’s bed. The only issue is convincing the printer to print a few thousandths of an inch higher than the actual bed level. Rather than change the home position on his Z axis, [Mikey77] used AutoDesk 123D to create 3D PCB designs. Each of his .stl files has a “spacer bar”, which sits at the bed level. The actual tracks to be printed are in the air a few thousandths of an inch above the bed – exactly the thickness of the substrate material. The printer prints the spacer bar on the bed, then raises its Z height and prints on the flexible PCB material. We’re sure that forcing the printer to print in mid-air like this would cause some printer software to throw errors, but the system worked for [Mikey77] and his Makerbot.
Once the designs have been printed, the boards are etched with standard etching solutions such as ferric chloride. Be careful though – these thin substrates can etch much faster than regular PCB.
Prototyping circuits is still a pain. The typical process is to order your PCBs, await their arrival, hand assemble a board, and start testing. It’s time consuming, and typically takes at least a week to go from design to prototype.
The folks at BotFactory are working on fixing that with the Squink (Kickstarter warning). This device not only prints PCBs, but also functions as a pick and place. Rather than using solder, the device uses conductive glue to affix components to the substrate.
This process also allows for a wide range of substrates. Traditional FR4 works, but glass and flexible substrates can work too. They’re also working on using an insulating ink for multilayer boards.
While there are PCB printers out there, and the home etching process always works, building the board is only half the battle. Hand assembly using smaller components is slow, and is prone to mistakes. If this device is sufficiently accurate, it could let us easily prototype complex packages such as BGAs, which are usually a pain.
Of course it has its limitations. The minimum trace width is 10 mils, which is a bit large. Also at $2600, this is an expensive device to buy sight unseen. While it is a Kickstarter, it’d be nice to see an all in one device that can prototype circuits quickly and cheaply.
Hackaday alum [Caleb Kraft] tipped us about a nice hack he got to see at the Open Hardware Summit this year. It is a flexible haptic strip made from a LED strip.
Cheap flexible printed circuit boards aren’t easy to find, so [Jacob] basically switched all the RGB LEDs of his strip with shaftless vibratory motors. The LEDs were addressed using WS2801 LED drivers so the hack also consisted in shorting the current feedback resistors. As a result, the motors will use as much current as the driver can give and [Jacob] can individually drive each motor. Luckily for him there already was an Arduino library called fastSPI to drive the strip, so he managed to make a nice haptic device in no time. In case you were wondering, the maximum number of motors you could drive is 32.
Our own [Eric Evenchick] also saw a lot of great project demos during his time at the OHS.
[via EE Times]