Four years ago, Brooklyn-based startup BotFactory successfully crowdfunded its desktop PCB factory, the interestingly named Squink, that lets users 3D print working circuit boards with conductive inks, and even fabricate circuit traces on a variety of substrate materials. After getting a little help from the Shapeways 3D printing service in developing its 3D printed toolhead, the startup closed a $1 million seed round of financing in 2016 – on the second anniversary of its $100,000 Kickstarter campaign, no less.
This financing, at least in part, went to helping BotFactory develop its second PCB 3D printer, the SV2, which offers finer tolerance, higher speeds, and a larger build area than the Squink.
Some companies, like BotFactory, like to put their new 3D printers to the test with interesting projects. The startup decided to use its latest PCB 3D printer to create edge connectors, which are, as BotFactory wrote in a blog post, “a cheap and simple way to avoid using standard connectors and having to open and plate holes, or to use SMT connectors.”
An edge connector, for the uninitiated, is the part of a PCB that consists of traces that lead to the board’s edge and will be plugged into a matching socket. They come in a varied selection, and usually need a specialized female connector. A PCI is a type of connector typically used inside desktop computers as motherboard expansion slots.
According to the blog post, “The goal here was to create a simple connector that we could plug in and remove very quickly into an ordinary USB A-plug, repeating up to 1000 times or until failure.”
Since no one in the office had an actual desktop computer, the project participants decided to start 3D printing edge connectors that would work with a USB. The goal wasn’t to maintain data fidelity after a large number of cycles, but rather to see how long it would last being plugged in and out. Several people predicted it wouldn’t even hang on for more than 50 cycles before failing.
First, they created a simple design for a set of USB ‘keys,’ using the EDA system Upverter, that included a resistor and a 1206-sized LED, which was very easy to pick and place.
“We thought about designing something complex, but the real goal was to determine if there would be any immediate risk of failure,” they noted.
Once the Gerber files for the USB key design had been uploaded into the SV2, it took less than five minutes to 3D print them, and about the same amount of time to cure them. BotFactory believes the whole process, starting with the design and including set-up and using PCB shears to cut out the boards, only took 15 minutes, as they noted:
“One of the big advantages of SV2 is our new heatbed/fan setup, which allows for extremely rapid heat-up and cool-down cycling. For Squink users, you might feel envious – we love it. It makes prototyping a whole lot faster!”
But the team’s favorite feature of the SV2 is its new one-part epoxy, which is just as strong as a two-part but dispenses much finer and cures rapidly.
Since no one wanted to volunteer their own computer for testing purposes, the USB key was plugged into a spare power adapter, and immediately worked. The key was rapidly plugged in, then removed, over and over again over a few minutes, and the team marked it down every 50 counts. The results were surprising – the durable USB pads still hadn’t broken after 500 cycles.
“By the time 1000 cycles hit, we weren’t even mad,” the blog details. “A 1000 cycles is better than daily use over a year – excellent results for prototyping devices that might be used in the field or in a customer’s hands for a short period of time.”
According to GCT, most USB connectors go through anywhere from 1,500 to 10,000 mating cycles, so 1,000 was a pretty “respectable” amount. However, while the part was fully operational, a closer look showed that the USB connection was pretty battered.
“Using USB connectors in your day-to-day prototyping is a really simple way to get a 5V source without any complicated connectors or wasted space and time,” they said.
BotFactory admits that it didn’t go too deep into designing USBs for data transfer for this durability experiment. But if anyone else wants to have a go, you can contact the startup for details on how to get access to its design files.
Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts in the comments below.[Source/Images: BotFactory]