Printed Circuit Boards (PCB) are important components used in the more high tier machines. Making them requires a few steps. First of all, craft an Empty PCB by throwing an Iron Ingot and a piece of Plastic in the Pressure Chamber.
Then there are two ways to make a Unassembled PCB. You can throw the Empty PCB in a Assembly line in which it will be lasered, or you can develop a PCB chemically by throwing it in a UV Light Box and then etch it, described here.
UV Light Box
The UV Light Box is a machine in which you can expose PCB’s to UV light, at certain places (which is determined by the Blueprint laying on top of the PCB). The exposure process takes a maximum of 10 minutes. When you wait these full 10 minutes you’ll have a 100% chance that the etching process (next step) will succeed. You can however expose the PCB for a shorter time, which will result in a lower chance of the PCB successfully being etched. The UV Light Box needs pressure to run, the tubes can’t be connected to the front, back or top of the machine.
PCB Blueprints only can be acquired via trading with Mechanics (PneumaticCraft Villagers). They spawn naturally or you can ‘make’ them in a Pressure Chamber.
The next step is to throw (literally) the Empty (exposed) PCB in Etching Acid. A bucket of Etching Acid can be crafted in a Pressure Chamber. The PCB needs to be etched for 5 minutes. You can pick it up while it’s being etched to see the progress. You’ll have to pick it up as a matter of fact, to prevent despawning. Seems like a nuisance, but now you have another thing to automate! After these 5 minutes, the Empty (exposed) PCB turns into a Unassembled PCB when succeeded, or in a Failed PCB when not. A Failed PCB can be thrown in a Furnace to be turned into an Empty PCB (not exposed).
Assembling the PCB
The final step is to mount the components on the Unassembled PCB.