Oct. 31, 2014 | By Alec
3D printing has been making circuit board manufacturing far easier and cheaper in recent years. Just a few months ago, we even reported on the intriguing portable Squink circuit board 3D printer. However, flexible circuit boards, that are perfect for small and unusual projects, remain very expensive.
All that could change, however, thanks to a cool project by Instructables user Mikey77. He has recently posted a guide for 3D printing circuit boards with just about any type of FDM printer. His handy tutorial could very well hold the key to easy and affordable circuit boards for any project you've been itching to do.
His secret? Ninjaflex Thermoplastic Elastomer (TPE) filament, an FDM 3D printer filament that has an interesting property: it sticks to copper. As Mikey explained, commonly-used filaments like PLA, Nylon and ABS 'do not stick to copper well enough to lay down a pattern that can be etched to create a circuit board.' But this TPE stuff, printed onto a copper substrate, is perfect for making circuit boards in your own home with your own printer.
Firstly, obviously, is design. Mikey relied on the free and popular 123D Design. It was drawn and then extruded to .011" thick. Crucially, he also added a spacer bar to the side of the pattern, which the extrusion head will reach first. 'When it is printed it prints the spacer bar first on the base and then jumps to the circuit board material and starts printing at the right height to accommodate the thickness of the circuit board material.
While working with Ninjaflex filament, you will need to fine tune your 3D printer a bit. This will likely depend on the printer you have, though you will not need a heated bed for this project.
Mikey used an older model of the Replicator 2, which required an extrusion head update. As for other printers, he advises the following: 'If you have a different 3d printer, you should check out Thingiverse for drive blocks that use a spring and roller bearing that will fit your printer. There should be a very small gap (orange arrow) below the bearing and drive gear and the hole where it goes into the hot end of the extruder. Ninjaflex is like a wet noodle and an excessive gap here will allow it to flex and jam.'
However, one thing is true for all types of FDM 3D printer and this material: make sure your bed is level! 'There is a very small margin of error for printing a thin coating on copper. To close and the extruder will clog, too far, and it will not stick well enough to etch. Your bed has to be very flat and very, very level. Nothing else will do.'
This can be achieved using calibration.stl to fine tune the levelling of the bed. Print it onto the middle of the bed in PLA. Measure all the ends and make sure they are within .002" of each other in thickness. 'Do not skip this step.'
Then there's just one more step before printing can begin: stick your flexible board material (which can be a thin copper clad board or plated conductive fabric) onto the print bed using an adhesive spray. This is necessary because it needs to be dead flat on the print bed.
Now you can start printing; if the Ninjaflex smears around a bit, you will have to adjust the STL file to thicken the spacer bar. And if it doesn't adhere properly, do the opposite.
Print the circuit pattern and then check to see how well it sticks to the copper circuit board. If it smears around, it is too close and you will have to adjust the STL file in 123D Design and thicken the spacer bar. If it does not adhere well you may have to make the spacer bar thinner.
If all things go as planned, you'll now have a printed circuit board. Simply detach it from your print bed, remove any adhesive residue (duct tape works well) and just etch off the bottom copper cladding using a standard Ferric Chloride approach. Just be careful with this last step, as these super-thin substrates etch off much faster than regular PCB would.
All in all, it's a quite easy process and definitely a cheaper option than store bought flexible circuit boards. Give it a try!
Posted in 3D Printing Applications
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Jamie wrote at 2/25/2015 7:30:16 PM:
Wow this is mind blowing to me. Thank you for this helpful post. I've been growing more an more interested in circuit boards and particularly love the winning designs on a circuit board design challenge from FirstBuild and Upverter. The winner noticed some shortcomings of the Raspberry Pi circuit boards and created a design to overcome it. I thought their graphic cleared it up for me (http://bit.ly/diffcircuit). Thanks again for the helpful post!
Ryan Casuna wrote at 2/16/2015 2:40:42 AM:
Were could i buy this materials?