Building complex development boards and projects with various component parts, you can sometimes forget that for the first step in the process, someone out there is designing and manufacturing the PCBs!
Star Simpson took to Digi-Key’s Maker.io to outline the whole process in all its glory and detail. “We sought to answer the question: what goes on behind the scenes at the PCB manufacturer?”
Some of what Simpson outlines is fairly straightforward, but there are certain details in the process that stir even the most latent inner scientist
The next step is an electroplating process, in which copper is plated onto the conductive pattern and on the hole walls of the PCB to meet the design requirements for the circuitry. The PCB is plated in a copper plating bath (an electrolyte of sulfuric acid/copper sulfate) that utilizes a DC power supply to apply current to anode and cathode bars. The panel to be plated is placed on a rack and connected to the cathode bar. Copper anodes hang in the solution from anode bars. As current is applied, copper from the solution is deposited onto the conductive surface of the board and onto the hole walls while copper from the anodes is broken down into the electrolyte. Typically, the PCB will be plated with a thickness of around 1 mil (0.001”).
After the copper plating is complete the panel will be plated in a tin plating bath to deposit a thin coating of tin which will serve as an etch barrier when the PCB is etched.
Awesome right!? Check out the whole post over at Maker.io. And if you want to see these boards in action, check out Simpson’s finished products over at Adafruit.com — the LED flasher kit, the stepped tone generator, and the voltage indicator.