Printed Circuit Board Lab

The first step in making an electronics project is prototyping. An initial design is made and then tested; usually using something called a solder-less breadboard. A solder-less breadboard consists of a two-dimensional grid of pinholes with a gap running down the middle columns. The columns of pinholes on each side of the gap are connected together along a single row inside the breadboard. Circuit components are inserted into the breadboard and wired together.

Source: electronicsclub.info

Sometimes complicated designs containing a large number of wires and components become difficult to deal with. In those instances it is useful to have a printed circuit board or PCB made. A PCB is similar to a breadboard in that it is a board, usually made of fiberglass. Instead the place of wires it has permanent copper “traces” on its surface which are the conductive interconnections between components. Components are then soldered to the copper trace “pads” of the PCB and the circuit complete.

Source: wikimedia.org

PCBs can be ordered on the Internet, but are expensive and take time to be manufactured and shipped. If you’re in the middle of prototyping a circuit and need to build and revise, all the ordering and waiting can be expensive and time consuming. I got tired of all the waiting. That’s why I have taken matters into my own hands and have made a PCB lab at home.

There are kits you can buy for making PCBs at home, but they are pricy and require making negatives, mixing photoresist and other darkroom techniques. The method I chose to make PCBs is more “do it yourself” than a kit. It’s also a lot cheaper.

Source: usm.edu

The first step in making a PCB at home is generating the artwork, a layout of the copper traces. The artwork is applied to a fiberglass board with a thin layer of copper covering its surface. There are several techniques for applying the artwork to the copper board, with photolithography being the most common. I use a technique known as the toner transfer method in which a mirrored version of the artwork is printed onto glossy photo paper, which is then heated and pressed onto the copper board. The toner bonds to the copper and the paper can be soaked in water and then dissolved away, leaving behind the copper board with an non-mirrored version of the artwork attached to it.

Source: slug.blog.aeminium.org

The toner covers and protects the traces underneath while the exposed copper can be etched away in acid. Typically the acid used in etching is ferric chloride, however to keep the cost as low as possible I use a special formula of hydrochloric acid. After etching the toner is easily removed with acetone revealing the shiny copper traces underneath.

Source: pcbfx.com

All that is left after etching is to drill the holes for the components and solder them in place. Being able to do this process at home makes prototyping go much faster and it’s a pretty cool experience.