Getting your own PCBs made is a rite of passage for the hardware hacker. Oftentimes, it’s a proud moment, and many of us choose to immortalise the achievement with a self-aggrandizing credit on the silk screen, or perhaps a joke or personal logo. However, as far as artistically customized PCBs go, the sky really is the limit, and this is the specialty of [TwinkleTwinkie], whose Supercon talk covers some of the pitfalls you can run into when working at the edges of conventional PCB processes.
[TwinkleTwinkie]’s creations are usually badges of one type or other — they’re meant to be worn on a lanyard around your neck, as a pin, or as a decoration added to another badge. The whole point is the aesthetic, and style is just as important as functionality. With diverse inspirations like Futurama, Alice in Wonderland and the shenanigans of the GIF community, his badges blend brightly colored boards with a big helping of LEDs and artistic silkscreening to create electronic works of art.
Keeping PCB Fab Houses from Upsetting the Artwork
These days, PCB fab houses offer more choice than ever, in terms of silkscreens, soldermask colors, and other options. However, fundamentally, their primary concern is to produce reliable, accurate, electronically functional boards — and it’s something that can cause problems for #badgelife hackers designing for more aesthetic reasons.
[TwinkleTwinkie] ran into this very problem during the development of the Arc Badge, a piece designed to replicate the famous arc reactor from the Iron Man and Avengers films. The basic idea of the badge was to have a base PCB which carries all the hardware, along with a spacer, and then a third top layer consisting of a PCB which the LEDs were intended to shine through. The prototype board worked well, with the fab house producing it on 1.6mm thick FR4 with white silkscreen and red soldermask. For the final product, wanting something a little fancier, black silkscreen was chosen instead. Ordered through PCBWay, this necessitated using their “Advanced Production Fab”, and a longer lead time, but after a few weeks the boards were ready.
Unfortunately, despite looking great with the black silkscreen contrasting with the rich red soldermask, there was a problem. When [TwinkleTwinkie] asked for black soldermask, this also led to a change in FR4 material, to a different grade which was more opaque than the prototype board. This led to the LEDs showing up very dim, and spoiled the visual effect that was desired for the ArcBadge. The dimming was so significant that users would no longer get the glow-through effect when wearing the badge under a T-shirt, a la Tony Stark. It took comparison with the prototype to figure out what had happened. PCBWay had simply used a higher-grade material when switching to the black silkscreen. Given that PCBs are sold as electronic products, and not for their optical qualities, they hadn’t done anything wrong, per se – but regardless, the new boards weren’t fit for purpose.
Order, and Order, and Order Again
The solution was simple – the boards would need to be reordered. In order to guarantee the LEDs would shine through and be truly resplendent, precautions were taken. The final board switched back to white silkscreen. As an additional precaution, in case PCBWay kept using the new material, the new part was instead 0.8mm thick, allowing it to block less light.
The redesign left [TwinkleTwinkie] with 250 coasters to give out, but his commitment to giving his customers a quality product is commendable. Despite nobody outright making a mistake, the final product would have been a little disappointing had the redesign not taken place. The Arc Badge, as delivered, glows with the best of them, and we’re sure everyone involved is wiser for the experience!