hammes hacks

When a electrical device needs to be a piece of art or used as a mechanical component, a printed circuit board is more than a piece of fiberglass with wires embedded in it. In chemical engineering applications internal holes which allow fluids to be transported through the PCB need to be placed in complex precise patterns. As art, holes can be used to create positive and negative space, allowing you to see a charlieplexed LED display as a snowflake. Creating complex shapes in PCB design software is difficult to impossible. However, it is easy in CAD software. In this talk I will present the project workflow I use to design and manufacture my PCBs. Additionally, I will discuss the problems I have run into during manufacturing and how these problems were resolved.

Making electrical-artistic and electrical-mechanical PCBs adds steps and complications to the usual PCB fabrication process. In this talk I will go over my project workflow and discuss how and why I do each step. I will also discuss problems I have run into during both the design and the manufacturing process.

An overview of my workflow is as follows:

• Make a sketch of what the final PCB will look like and what it will do.
• Make a schematic of the electronics (kicad).
• Assign footprints to the electrical components (kicad).
• Check the manufacturers webpage for the design criterion on internal cuts.
• Create a CAD file of the PCB outline (no electrical connections) (fusion 360/solidworks etc).
• (optional) Conduct multiphysics simulations of the PCB outline, to find an optimal design (comsol etc).
• Make boxes to represent the footprints of the electrical components and place these where you want them to be on the final PCB (fusion 360/solidworks etc).
• Think about how the boards will be panelized and insert mouse bites/tabs for V-cuts as needed (fusion 360/solidworks etc).
• Export a 2D drawing of the PCB including the components.
• Make a PCB file with all the components (kicad).
• Import the 2D drawing of the PCB as the edge cuts in the PCB file (kicad).
• Place electrical components in the correct location and delete the edge cuts which are just being used as markers (kicad).
• Use a routing software to connect components or connect these manually.
• (optional) Panelize the boards by making a new PCB file and importing the single PCB.
• Export the gerber files.
• Check that the outlines are correct in the gerber files and clean up machining code if necessary.
• Upload files to manufacturers webpage and include an image of which places should be milled out.

Common problems have included:

• V-cuts on non-rectangular PCBs.
• Keepout zones on internal edge-cuts.
• Gerber file generation errors caused by internal edge cuts and pannelization.
• Some manufacturers do not do internal edge cuts.
• Boards are mechanically weakened by internal cuts.