See Your Circuits in All Their Glory with This Glass-Based "PCB"
Printed circuit boards, or PCBs, are essentially circuits that have been etched onto a piece of substrate material in order to use less space than something using wires and plugs.
Commercially, PCBs are opaque, which does not allow anyone to easily observe the traces unless they get extremely close. It was for this reason that Okubo Heavy Industries wanted to build his own transparent version for a better viewing experience.
A normal PCB consists of several layers that are all sandwiched together to form the final product. These include the substrate, which is typically a dense fiberglass board onto which everything else is attached; the copper traces that actually conduct the electric current between various components; soldermask that covers the traces and substrate in a protective coating; and finally silkscreen printing which is how those tiny letters, numbers, and illustrations are able to be shown.
This more transparent version largely follows the layering model laid out in the previous section, albeit with some pretty major caveats. Rather than using any kind of opaque substrate base material, a glass microscope slide was chosen instead due to its thinness and transparency.
The traces were formed by taking copper tape and routing it in a certain pattern to create the circuit, which in this case is a solar-powered blinking light demonstration that has an ATtiny85, four LEDs, and a small solar panel at the top. Once everything was soldered together, this novel clear "PCB" was finished.
This glass-based PCB certainly looks quite different compared to the normal mass-produced kind, and being able to see the copper paths from all sides is something neat to admire.
However, the wide traces and lack of a protective top layer does prevent this design from being used for much more than a fun one-off project. You can view the Glass PCB Solar Arduino here in this Reddit post.