Making Printed Circuit Boards

Workshop 88 has growing expertise in making simple single-sided printed circuit boards.  In addition to boards for individual members’ projects, we’ve even made a small production run of boards for the badges we provide for a security convention.

Physical board manufacture

Once the circuit has been designed, making a board consists of the following steps:

  • Board layout – drafting the exact pads and traces on the board to mount and interconnect the components to implement the desired circuit.  Eagle is one common tool for this step, and we’ve even done basic classes on how to use it.
  • Resist layer – putting a layer of material on the raw board in the pattern of the desired pads and traces.  The two  approaches we’ve tried are:
    • Toner transfer  Transferring laser printed toner images to the board.  The actual plastic toner is the etch resist, and must be melted off the original and onto the PCB blank.  While it’s possible to do this with a conventional iron, we’ve had better success with an electric laminator.
    • Photographic process using presensitized board material.  Excellent results have been produced quite consistently with this approach.  Black-on-clear artwork is produced in an inkjet or laser printer to begin this process
  • Etching – dissolving all the copper except the desired pattern with a chemical etching bath.  The chemicals involved are somewhat caustic, and there are significant environmental concerns with discarding used etchant.
  • Removing the resist layer – to expose the copper paths for soldering.  Acetone works very well for the photo resist.

An alternate methodology is CNC machining away some of the copper layer to electrically isolate the desired traces.  This purely mechanical process avoids all chemical processing.  We’re just beginning to explore this, and have not yet made any boards this way.

Drilling the board

While we have a couple of nice Dremel drill presses that work well for hand drilling boards, we’re moving toward using the Shapeoko as a CNC drilling machine to automate the process.  Significant progress has been made on using gcode generated from Eagle files to automate this step.

Actually, the (surmountable) additional step of drilling the board has led to considerable interest in using surface mount components – which don’t need holes!

Reflow soldering

Etching chemicals