8. Electronics Production¶

Individual Assignment¶

Make and test a microcontroller development board that you designed

Button Blink PCB¶

KiCad Design¶

To see my detailed design process, you can visit my Electronics Design page.

This is the final schematic:

This is my final PCB design in the PCB Editor:

This is my final PCB design in the 3D Viewer:

Milling¶

Elle Hahn helped me mill my PCB. She walked me through the settigns to make sure I did it correctly. Also, there was an issue with the milling machine we were using, so we needed to use alligator clips in two specific locations, so she helped me with that.

To ensure that I had learned how to do it correctly, I guided Andrew Puky through the necessary settings when he was milling.

This is the homed milling machine I used:

In ninth grade engineering, I made a milling machine workflow for the Othermill milling machine, so I decided to follow this workflow when producing my PCB. Below is my ninth grade workflow with necessary adjustments made:

Turn on the Othermill milling machine.
Open the Bantam Tools software.
In the “Initial Setup” tab, open your Gerber files.
In the “Material Setup” tab, insert the size of your PCB.
Always use calipers to double check the measures of your PCB.
Apply double sided tape to the back of the PCB, being careful not to let the tape overlap in any spots but also ensuring that there is enough tape for the PCB to stick. There was already a piece of copper down when it was my turn to mill, so I did not need to put a new piece down.
Clean the aluminum spore board to remove any dust and leftover adhesive with an alcohol swab.
Once all the alcohol is evaporated, press the back side of the PCB onto the aluminum spore board firmly.
You may want to wear a glove because the oils on your hand can oxidize the copper on the PCB if you care about looks.
Back in the software, in the “Initial Setup” tab, you must change the bit size for milling. I used a 1/32” bit for this PCB. It was already installed in the milling machine because someone else had used it before me, so I did not need to install it.
For single sided PCBs, they occur in order from smallest bit to largest bit, and for double sided PCBs, you must turn off the cutout operation, “Outline,” for the first paths to make the milling operation easier.
The bit holder should only ever be open when you’re selecting a bit because they can easily harm people due to their sharpness
Use the two wrenches on top of the machine to loosen the collet and put the bit you chose into it and then tighten it using your fingers. Once you think it is tight with your fingers, finish tightening it with the wrenches.
Tighten it firmly but not so firmly that the threads on the column start to strip.
Back in the software, position the material under the “Material Setup” tab.
In the “Plan Setup” tab, change the plan offset too move the tool paths in from the bracket a few millimeters, so the bit will not run into it.
Install the correct bit if it is not already installed.
Under the “Jog” tab at the bottom, select “Install Tool,” and then follow the steps.
Whenever doing this process, keep your hand hovering over the red “e-stop” button on the milling machine in case you hear a grinding noise and need to stop the machine, clean the bed, and restart the z-height finding operation. The z-height feature on the milling machine was not working properly, so we needed to use alligator clips while homing the machine and setting the z-height. Before milling, it was crucial to remove the alligator clips.
Once you have found your z-zero, go back to the software, and under the “Summary Run Job” tab, press “Machine All” and watch the mill.
If something were to go wrong, it would happen in the first few seconds of machining.
After it is finished, be careful not to inhale the dust. Fiberglass is toxic.
Vacuum out the machine, remove and put away the bit, and clean the spoil board with an alcohol pad.

Milling my PCB:

This is my milled PCB:

Soldering¶

My milled PCB had one issue I did not realize in my design: one of the grounds used in the circuit was the ground under the Xiao RP2040 and not the ground pin. This was not a big enough issue for me to have to remill, but it was still not ideal because if I soldered it even a little bit off, and the ground under the RP2040 was not touching the traces, then it would not work properly. Elle Hahn mentioned to me that the surface mount push buttons were mot working for anyone who had tried them yet, so we both decided to use through hole push buttons instead. This was probably not the best decision, but it worked. If I were to remill the PCB again, that is definitely soemthign I would change. When soldering it was CRUCIAL to make sure that the LED polarity was correct and that the button was facing the correct direction.

This is my fully soldered PCB:

I was not expecting my PCB to work because of the ground issue I mentioned earlier and because my soldering job was not the most beautiful or accurate, but I was very happily surprised that it worked first try!

When I plugged the Xiao RP2040 into my computer, the LED turned on, which was immediately a good sign.

Then, I ran the code from my Embedded Programming week to make an LED blink using a button, but I changed the pin numbers to the correct ones for my PCB design. The button worked, but instead of starting with the LED off, the LED started out turned on, but that was a very quick and easy issue to resolve.

Button working backwards (LED starting on):

One strange issue that none of classmates had was that my LED was very bright, which makes me think that the resistor I used may have been mixed up in the wrong bin and should have been a resistor of a higher resistance, but that was not a significant problem.

Final PCB¶

This is my Button Blink PCB working properly:

Final Project PCB: Step Response¶

KiCad Design¶

Designing this board was definitely much more difficult than I initially anticipated. I followed Neil’s board and also looked at this version of Neil’s board to try and get a good idea of using step response, but it was difficult to find all the components he used. I tried to make my own touch pads which was much more difficult than it should have been. I ended up just using surface mount resistors for my touch pad component.

I followed a step-by-step process from ChatGPT to make the touch pads fro my PCB. I eventually stopped trying to make my own ones because the pads in the PCB editor were not working correctly, but ultimately, I would say it was a good learning process and if I had to do it again, it would likely be much easier and more efficient.

First, I had to create the symbol in the Schematic Editor. This was definitely the easiest part.

Initially, I forgot to include something to connect the touch pad to other components, but that was an easy fix.

Then, I had to create the footprint for it in the Schematic Editor. I kept debating if I should make the pad circular or rectangular.

To see if the footprint worked, I tried updating the PCB from schematic.

When I got the footprint to appear, I could not connect it to other components in the PCB Editor even though it connected well in the Schematic Editor.

After dealing with issue for several hours and using ChatGPT to troubleshoot, I eventuall just decided that I would use a surface-mount resistor component in KiCad as my touchpad.

Here is the final schematic for my step response PCB:

Here is my step response PCB in the PCB Editor:

Here is my step response PCB in the 3D Viewer:

Milling¶

I followed the same workflow as above when milling this PCB.

Here is an image of the bit being changed:

Here is the copper board before being milled:

Here is the PCB being milled:

Here is the milled PCB:

Soldering¶

Here is the soldered PCB:

As you can see, the spot where I used the resistors for the touchpads do not have any component on them.

Group Assignment¶

Our group assignment for this week was to characterize the design rules for your in-house PCB production process: document feeds, speeds, plunge rate, depth of cut (traces and outline) and tooling. I worked with the same group as last week which was all of the girls who are doing Fab Academy. Here is a link to our group page for this week. I completed the speeds and feeds section for this week.

Reflection¶

I enjoyed this week. It was cool to learn how to produce a PCB that I designed myself because that is definitely a skill that will come in handy later. It was also cool to make the first prototype for a board that I will use in my final project. I am sure there are some changes that I will need to make later, but it was cool to get a solid idea formed. I also enjoyed the group part of our project even though we were pretty crammed for time due to our school spring break.

AI Help¶

Here are all my ChatGPT searches from Week 8: PDF

Files¶

KiCad design I used for my Button Blink PCB

KiCad design I used for my Step Response PCB

Last update: April 20, 2025