A self-powered computer in actual credit-card size (~1mm thick)

# I built a fully self-powered computer in actual credit-card size (~1mm thick) Source: [https://old.reddit.com/r/electronics/comments/1td7yxl/i_built_a_fully_selfpowered_computer_in_actual/](https://old.reddit.com/r/electronics/comments/1td7yxl/i_built_a_fully_selfpowered_computer_in_actual/) For years, devices like the RbPi have been described as “credit\-card sized”\. And of course the message is rather the footprint, but at some point I became obsessed with taking that idea one step further: What would it take to build something that is*literally*sized like a credit card? *I've got a slight feeling that you really don't seem to like questions here, but I hope this rhetorical one is okay :P* That question slowly escalated into months of experiments to find solutions for things where default methods won't work\. I can't use large, rigid components, connectors, and find a way to make my own custom flexPCB\. And after months of tinkering, I made the first prototype\. Fragile, but it works within the goal of not exceeding 1 millimeter\. Somehow, news pages have picked this up and described it as "revolutionary" which is a bit far fetched, but I feel flattered 🤭 To be fair, 'computer' might be a little overstatement, but it's technically perfectly within the definition of one\. If you should have suitable words for it that sounds cool, feel free to suggest ^^ **The prototype includes:** - ESP32\-C3FH4 w/ WiFi & BLE - NFC read/write - 1\.54" 200\*200 E\-Paper display - ultra\-thin LiPo battery including charging circuit and power path management - accelerometer Finding small/thin enough components wasn't really the main challenge, mechanical stability was\. Solder and general material fatigue, pressure distribution \(particularly focused pressure\) and other strain related issues were the real problem\. This doesn't even include battery protection and some other things to solve\. At this scale, the project turned into a weird mix of electrical, mechanical and chemical engineering\. A few things that became clear over time: - preventing strain is much easier than surviving strain - tiny real\-world tolerances start dominating the entire design near the physical limit - many “thin enough” components stop being thin enough once assembly is considered - FPC connectors are basically obsolete, forcing me to get creative and solder each single wire for each 0\.5mm pitch pad one by one\. The prototype is fully self\-powered and running from its internal battery\. I documented a large part of the engineering process, including the process of etching my own flexPCB, on my[GitHub repo](https://github.com/krauseler/muxcard)\. And yes, it's not like this thickness is a necessity, going just 0\.5mm thicker would probably have saved me months of engineering\. This entire project was probably motivated way too much by the 'disbelief' factor 😄 I am curious on your thoughts on this\! :\)