Zero to PCB: Circuit Requirements

In this blog post I am going to be covering developing a set of PCB requirements.

Unfortunately, there is not one set of requirements that I can list out which covers everything that you could possibility consider. The requirements for a LED badge and requirements for a motherboard going into outer space are so wildly different I don't know where to begin. However, if I may presume that you are building a certain class of electronics the following list of questions may help you build your own set of requirements.

Don't worry if some of these don't make sense the answer is probably no or it doesn't matter for you. For example I didn't know what a pick and place machine was until fairly recently.

  • Functionality
    • What is this PCB expected to actually do?
    • Does it need to physically interact with the world in any way?
  • Physical Considerations
    • Do I have physical constrains? Height, width, volume, weight?
    • What temperature range will the circuit board be expected to operate in?
    • Will it operating in an location will a lot of RF emissions?
    • Will moisture be an issue?
    • Is it a high vibration environment?
  • Power Requirements
    • What voltage and current levels do we expect the PCB to be able to handle?
    • Where is the power coming from? Do I need a Battery?
  • Manufacturability
    • How many will be made?
    • Are they being hand assembled or is a robot doing it (pick and place)?
    • Can my manufacturer actually make it? (Square holes? Really?)
  • Budget and Timeframe
    • What the budget per PCB?
    • Is there a deadline we have to meet? (Maybe some parts have a lead time)
  • Compliance and Standards
    • Does my PCB need to meet any regulatory standards or certification? (RHoS, FCC)
  • Other
    • Does my PCB need to be pretty?

Example: LED Badge

The led badge I am building is for Allspice's company meetup. While things like soldering, schematics, and component selection are well known for the electrical engineers on our staff, for the non trained like myself the badge will be a learning experience. My hope is if I can get this done on time (December 2023) then each of us can hand assembly their very own badge :smile: :celebration:.

Since the badge is relatively simple the requirements are fairly straight forward.

I will attempt to break them into groups similar to the question grouping above.

  • Functionality
    • Needs to light up and display an interesting pattern on the front of the pcb. There are no hard requirements on the pattern and interesting is subjective but thats okay.
    • The pattern should change over time.
    • Need to be able to turn it on and off
  • Physical Considerations
    • I want it to be able to be pinned to a shirt or backpack so it can't weigh that much.
    • I also want it to be "badge sized" which I am going to say is about the size of a teensy, about 50mm x 50mm.
  • Power Requirements
    • Needs to be able to stay on for at least an hour.
    • It sort of needs to be battery operated as I won't be connected to a power outlet all the time.
    • Beyond that it will depend on my component selection with relied on my power budget :head explode:.
  • Manufacturability
    • Since this will be a team building activity all components must be hand solderable.
  • Budget
    • I don't plan making a ton of these so < $20 per board.:
  • Timeframe
    • I need this done by end of December so long lead times are a no go.
  • Other
    • Part of the functionality is how pretty it is, so the ability to have PCB art on the board is important to me.