or: How I Learned to Stop Worrying and Love the Board

Alon Gruss 20/11/16

Tl;dr:

I made a tool that converts an image into multiple PCB layers - pixel brightness to board opacity.

source on Github

1. You are not limited to your discipline!

As a Designer by trade I like to jump head-first into new disciplines which I know nothing about, learn to control the terminology and try to mess around in unexpected ways. I am also lucky to share studio space with Arkadi Rafalovich, A talented engineer and omni-potentialite, who inspires and guides me through learning the basics of electronics and Eagle PCB design.

While diving into the subject I was constantly visualizing and thinking about the tools that are missing for me, the tools I need for implementing my art and design.

(I recommend Sparkfun’s tutorials).

2. Most PCB’s are boring!

PCB’s are usually designed functionally without any visual attention, A very boring rectangle. Sure, they have their digital charm with mazes of tracing running along the board, but as a user, I prefer my PCB’s when they're inside my products. Covered in a well designed injection-moulded shell.

I use the word ‘usually’ because sometimes you get boards like the Defcon badge - which can masterfully merge function and design to create a fun user experience.

Or this wonderful PCB-USB-Business card by Frank Zhao.

3. The Artist in the Engineer

So, what’s different in business cards and convention badges? These are where the engineer isn't working for a client, he relaxes a bit and has fun with the design tools. He’s not just a cog in the product development process. When he has no restrictions.

Sadly, even then, the board designer dare only to use the tools given. Drawing only in the ‘Silk’/’Copper’ layers or slightly shaping the board’s outline in the ‘Dimension’ layer.

4. All the layers!

Some of my past Design projects deal with layered/laminated materials and the smart use of the different layer properties:

Those were opaque materials. What intrigued me with PCB design-wise, was the ability to play with material’s opacity and the light transfer through the board. Artistically I thought I can convey a more complete message and user experience by having graphics that support and integrate with the board’s functionality.

5. Testing the hypothesis

I searched google for leonardo da vinci’s portrait of Mona Lisa (which I consider globally identifiable) and saved one of the results to my PC.

Opened it up in Gimp. scaled it down (nearest neighbour) and duplicated it to a couple of layers.

I then run a threshold filter on the layers changing the value a bit in each one and saved the layers to separate files.

Only then have I noticed that the new versions of Eagle already have a built-in script for importing image, from colors to layers. “That’s great! This saves me a lot of time” or so I thought.

Don’t misunderstand, It's a really great tool, just not for my purposes.

You see, I need to control the cumulative combination of layer opacities in order to achieve my goal. I aim for the PCB to be facing up (showing the top layers).

For example:

Lightest - clear from traces or solder mask on both sides. ( no top + no bottom + yes tstop + yes bstop )

Light - clear from traces on both sides + solder mask only in back (bstop). ( no top + no bottom + yes tstop + no bstop )

Medium - ...

Dark - ...

Darkest - ...

We also have:

White Silkscreen - requires the top solder mask layer and the top silk layer (... + no tstop + yes tsilk )

Copper trace - requires the top trace but without soldermask.

You might have noticed that some layers control the lack of material and must be treated as a negative. That’s a bit confusing, so here is a guide table:

( legend: x = no || ⎷ = yes || ? = doesn't matter || n = inverted )

Color (layer No.) Top (1) Bottom (16) tStop (29) bStop (23) tPlace (21) bPlace (22) 0 x x ⎷n ⎷n x x 1 x x x ⎷n x x 2 ⎷ ? x ? x ? 3 x x x x x x 4 x x x x x ⎷ 5 x ⎷ x x x x 6 x ? x ? ⎷ ? 7 ⎷ ? ⎷ ? x ?

6. Lessons learned

I ordered the boards from Seeed...