Soil Moisture Business Card | Part 1: Research and Design Goals
PCB-based business cards are the calling card of many freelance electrical engineers, particularly those with a product design focus. I knew as I looked towards networking and building a platform over the next 6-12 months it was something that I would like to have up my sleeve when meeting someone new.
A typical business card is designed to communicate the brand of a person, their style, personality and market positioning. For me, I also want it to communicate technical ability, creativity and the ability to procure electronic systems at low cost.
This being the goal puts me in a smaller crowd - those who design PCB business cards that fulfil an actual function, a very interesting design exercise.
I ended up designing a business card that can tell you the soil moisture of a plant. But I’d like to walk through how the process I got there - as I believe that creativity is enhanced by having strong design goals from the outset. These goals are then translated into technical requirements and eventually a complete product concept.
Designing on the shoulders of giants
Like anybody, I started with a Google search. There are two amazing examples of these on the internet that stand head-and-shoulders above all others. I took these as inspiration when embarking on my own design process.
These are Mixtela’s StyloCard and George Hilliard’s Linux Business card. Please check them out as I reference their work heavily here. Mixtela creates more beautiful things than I can, and unlike me, George can create things with an OS.
These business cards share a common styling that has defined the genre - a Matte black soldermask, with white silkscreen text and ENIG pads giving beautiful golden accents.
But there is a key weaknesses that both of these business cards have (and the litany of similar business cards that you can find by searching “PCB Business card” on youtube suffer from even more).
Its functionality can’t be demonstrated at the point of handover.
This is almost an inevitability for two key reasons:
The business card needs a power source.
The business card needs a complete set of input and output interfaces.
The above exemplars address these needs by including a USB A plug - extremely cleverly implemented by cutting off a corner of a 1mm thick PCB, and soldering another layer on to create a 2mm thick tongue that works as a USB-A connector. I recommend reading Mixtela’s post on his stylocard here, for a better explanation of how to do this.
Mixtela beautifully creates a USB-A connection by layering the PCB itself.
However, they both then need a computer to operate, which means a demonstration is not practical in the usual settings of passing around business cards.
My other goal is to design something more universally understood - users of the StyloCard and LinuxCard need to know how to use a MIDI input device, or a Linux shell via virtual serial port respectively.
While professionals in the relevant industry are more likely to understand these than an average person, they narrow the appeal of the application itself. These business cards are primarily only impressive to those that understand what goes into them from a technical design perspective.
The sad reality is that often the stakeholder with the money is the one that does not have the technical knowledge to understand what you do.
With all this in mind I settled upon the 3 main requirements for my design:
Functionality that can be demonstrated at the moment of handover.
Usability and understandability by someone with no technical knowledge.
Minimum total thickness.
