This week, I focused on designing, fabricating, and assembling a custom PCB. I used KiCad for schematic and PCB design, then fabricated the board using milling and laser etching, and finally assembled and tested it.
Learning Objectives
Select and use software for circuit board design
Demonstrate workflows used in circuit board design
Assignments
Group Assignments
characterize the design rules for your in-house PCB production process
As part of the group assignment, we tested the trace width and spacing capabilities of different PCB fabrication tools, including the milling machine, laser engraver, and vinyl cutter. The goal was to determine the minimum trace width and spacing each method could reliably produce while maintaining proper electrical isolation.
We began by fabricating test patterns with varying trace widths and spacing on different materials. The milling machine produced the most precise results, but smaller trace widths required careful tool selection and calibration. We experimented with 1/64" and V-bit end mills, finding that the 1/64" end mill provided consistent results down to 0.4 mm trace widths. The laser engraver, while faster, had limitations due to excessive burning at high power settings, making it difficult to achieve fine-pitch traces without over-etching. The vinyl cutter, used for flexible circuit fabrication, performed well for simple, low-resolution circuits but struggled with fine traces due to material stretching and adhesion issues.
By comparing results across these fabrication methods, we gained a better understanding of their strengths and weaknesses. Milling offered high precision but required more time and careful calibration. Laser engraving provided rapid results but needed fine power control to avoid overburning. Vinyl cutting was useful for rapid prototyping of flexible circuits but had resolution constraints.
Learning Section
How are PCBs made
Industrial PCB Manufacturing
Fabrication Techniques: Milling/Laser/Vinyl
Terms and Jargons in PCB
Soldering Essentials
Reflow
Individual Assignments
Designing the Development Board
The design of the development board was done during the Week 6: Electronics Design. I designed a development board using the XIAO ESP32C6 at it's core. I named the board AXIAO - Ashish's Board. You can view the whole design process in the week 6 documentation
Schematic Design of Circuit
After the design was finalised after making some edits according to the design rules and constratints we found during the group assignment. Acccording to the tools available at our lab and the constraints of the tools, we added these values for trace width and trace clearance.
Design Rules
After assigning the design rules I added the traces and the final PCB design can be seen below.
PCB Design of Circuit
Setting up the PCB Design for Milling
The PCB design needs to be converted into GERBER and then into PNG to be used in the Fab MODS program. The following section shows the steps to obtain the gerber files for our PCB.
Plot the GERBER
The plotting of the PCb genertes it's GERBER files in the folder /gerber. You can change the format in the window using
Generating GERBER Files
gerber2PNG
I used gerber2PNG tool made by Fablab Kerala
gerber2PNGSchematic Design of CircuitSchematic Design of CircuitSchematic Design of CircuitSchematic Design of Circuit
Making the Development Board using Milling
Toolpath Generation using FAB mods
I used Fablab Mods software to genrate the toolpath for my PCB.
Schematic Design of Circuit2D Toolpath3D toolpath3D Toolpath
Fabricating the Development Board
Schematic Design of CircuitSchematic Design of CircuitSchematic Design of CircuitSchematic Design of CircuitSchematic Design of Circuit
The engraving of the top layer was done using the 0.2 mm 60 degree V bit. The V bit was the one available for
The cutting of the outline using 1/32 inch end mill
Schematic Design of Circuit
Collect the components
Before assembling the components, we need to acquire the necessary components. KiCad provides a plugin which can be installed and used to make a Interactive Bill of Materials for easier visibility and list the Materials for requesting in our lab.
Interactive HTML BOMHow to use Interactive HTML BOMSchematic Design of CircuitSchematic Design of CircuitSchematic Design of CircuitSchematic Design of CircuitHTML View BOMSchematic Design of Circuit
Request Components from Fabstash Inventory
The components from our inventory are organised and need to be acquired by requesting them from the fabsttash inventory.
Fab StashSchematic Design of CircuitSchematic Design of CircuitSchematic Design of CircuitSchematic Design of Circuit
Assemble the Development Board
The collected components are soldered using the solder station and tweezers.
Soldering Station
The assembly bench consists of all the necessary parts required to assemble the fabricated PCB. The devices availbel at the bench are: Soldering Station: Soldering Iron and Heat Blower, Tweezers, Flux, Exhaust System, Solder Wire, Desoldering Pump and Wick
Soldering StationSoldering ProcessSolderingAssembled PCBAssembled PCBSchematic Design of CircuitSchematic Design of Circuit
Visual Inspection using Microscope
Schematic Design of Circuit
Soldering Guide
After I soldered, I was told that at some places the solder was little too much. Then I saw this guide to good solder. Most of my solders are blobs. I recalled from the class that the solders should be shiny. Therefore I tried to make it shine somehow adding more solder wire. Therfore the blobs. But at some places the solder overflowed into the traces.
Test the Development Board
Schematic Design of Circuit
I used the connectivity mode to test if there was any shorting on the circuit and the power lines. I found no issue with board and thus started the program.
Hero Shots of AXIAO DEV Board
Schematic Design of CircuitSchematic Design of CircuitSchematic Design of Circuit
Getting Started with AXIAO Dev Board
Schematic Design of CircuitSchematic Design of Circuit
Program Development Board
Blink LED Program
int ledPin = D3 //Builtin LED pin on AXIAO
// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin ledPin as an output.
pinMode(ledPin, OUTPUT);
}
// the loop function runs over and over again forever
void loop() {
digitalWrite(ledPin, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(ledPin, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
}
//The Blue LED Starts Blinking
LED with Builtin Push Button
const int buttonPin = D3; // the number of the pushbutton pin
const int ledPin = D8; // the number of the LED pin
int buttonState = 0; // variable for reading the pushbutton status
void setup() {
pinMode(ledPin, OUTPUT); // initialize the LED pin as an output:
pinMode(buttonPin, INPUT); // initialize the pushbutton pin as an input:
}
void loop() {
// read the state of the pushbutton value:
buttonState = digitalRead(buttonPin);
// check if the pushbutton is pressed. If it is, the buttonState is HIGH:
if (buttonState == HIGH) {
// turn LED on:
digitalWrite(ledPin, LOW);
} else {
// turn LED off:
digitalWrite(ledPin, HIGH);
}
}
