8. Electronics Production¶

Weekly Assignment:¶

Individual Assignment:

Make and test a microcontroller development board that you designed

Design¶

I used these components in my design:

(From left to right, top down, Module_XIAO_ESP32C3, LED_1206, R_1206, Switch_Tactile_ESwitch, all of which can be found in the Fab academy library downloadable here)

When I finished my schematic design, I ran an Electric Rools Check (ERC) and assigned footprints.

In the PCB editor, I arranged my components in the way I wanted them to be and made my tracks 0.5mm thick.

I opened up the 3D viewer and double checked that it was what I had in mind.

Printing¶

For printing my PCB in-house, I needed the F.Cu and Edge.Cuts layer files as well as the drill files for the holes.

I used the 1/64" Flat End Mill and the PCB Engraving Bit 0.005"

Soldering¶

-- Referring back to my electronics design week when I first tried soldering, I learned an important lesson: not to use solder paste for surface mount soldering. These were the pictures for reference.

On my new board, I started with the button because it was larger and I was confident in my abilities to solder it on.

The method I found worked for me was to add a bit of solder at one of the two points and then use tweezers to hold my component down as I melt the solder. With that side secured, I could move to the other without worrying about it shifting. The only issue with that was when I had to solder super small components and the other side would melt as well, but tweezers ultimately held it all together.

After soldering each component, I'd use the multimeter to check for continuity. For the resistors, Angel let me know that I should not expect to hear a beep, which was helpful because I was about to crash out and resolder my resistors.

On my second resistor, I created a huge mess and was worried I created a solder bridge. I tried using the copper braid to strip the excess solder off, but it did not really work for me. I switched to using the solder sucker, which worked more effectively. As for the bridging, I just scraped the solder away from the traces so that the sides around the trace did not touch.

When I finished my LED, I used continuity to check if it would light up when some voltage goes through, which is properly did.

And then I soldered on my microcontroller.

I opened Arduino to upload the code I got from ChatGPT. Here is a public link to the conversation. This was the C++ code:

#define LED_PIN 1
#define BUTTON_PIN 16

void setup() {
    pinMode(LED_PIN, OUTPUT);
    pinMode(BUTTON_PIN, INPUT_PULLUP); // Assuming the 10k pull-up resistor pulls it high
}

void loop() {
    if (digitalRead(BUTTON_PIN) == LOW) { // Button pressed (assuming active-low setup)
        digitalWrite(LED_PIN, HIGH); // Turn LED on
    } else {
        digitalWrite(LED_PIN, LOW);  // Turn LED off
    }
}

Once connected to power, the LED would light up when I pressed my button, which was how I intended it to be.

It can be seen more clearly in this photo.

Group¶

This week's group assignment 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. We also had to document the workflow for sending a PCB to a boardhouse.

Individual Contribution¶

My contribution was on documenting the workflow for sending a PCB to a boardhouse:

The reason you would send a PCB to a boardhouse is to get professional fabrication with high precision. Instead of manually etching or milling, you upload design files, and the manufacturer handles printing, drilling, and finishing. Some boardhouses, like JLCPCB, also offer assembly services, soldering components directly onto the board.

Assuming you have your design finished, perform a final Design Rule Check (DRC) to detect any errors
Open the Gerber Export tool in your EDA software
Generate Gerber files for the following layers:
Top & Bottom Copper Layers (GTL, GBL)
Top & Bottom Solder Mask (GTS, GBS)
Top & Bottom Silkscreen (GTO, GBO)
Board Outline (GKO or GBR)
NC Drill File (Excellon format, .TXT or .DRL
Open the Gerber files in a viewer
Check that all layers are aligned correctly, verify hole placements and sizes, and confirm that any silkscreen text is legible and positioned properly
Select all Gerber files and the NC Drill file and compress them into a .zip archive. Double-check that all necessary layers are included before proceeding

Go to the website of the boardhouse you want to send your PCB to and select the type you want by clicking "Quote Now" (I went with JLCPCB)

Upload your .zip file where it says "Upload Gerber File"

Configure the PCB Specifications by going through the rest of the page
Choose the PCB quantity and size (JLCPCB automatically detects dimensions)
Select the number of layers (1-layer, 2-layer, or more)
Choose the PCB thickness (default: 1.6mm)
Set the copper weight (default: 1oz/ft²)
Pick a solder mask color
Choose a surface finish (default: HASL, or ENIG)
etc.
Review and confirm the final settings

Choose PCB Assembly (Optional). If you want your components soldered as well, there's another option to toggle below called "PCB Assembly"
Upload a BOM (Bill of Materials) and Pick & Place (CPL) file
Select components from JLCPCB’s parts library
Confirm placement and approve the assembly preview
Review the order summary to ensure everything is correct.
Upon arrival, inspect the PCBs for defects (check traces, silkscreen, and hole alignment)
Use a multimeter to check for continuity and short circuits. Power the board with a regulated power supply and check voltage levels. Test individual components and signals with an oscilloscope if needed.

Last update: March 28, 2025