ELECTRONICS DESIGN
Designing and fabricating a custom development board with KiCad
Introduction to Electronics Design
This week was dedicated to learning how to build our own circuit, which enabled us to acquire fundamental skills and knowledge in electronic design. Understanding these concepts paves the way for future advancements in electronics as we delve deeper into the basic concepts for electronic operations:
- Voltage (V): The electric potential difference between two points
- Current (I): The rate of flow of electric charge
- Resistance (R): Opposition to the flow of current
- Power (P): The rate at which energy is transferred
The fundamental relationship between voltage, current, and resistance:
V = I × R
Where V is voltage in volts, I is current in amperes, and R is resistance in ohms.
For a more comprehensive understanding of these concepts, you can refer to the group assignment online.
Group Assignment: Test Equipment
For our group assignment, we used various test equipment to observe the operation of a microcontroller circuit board. The minimum requirement was to demonstrate the use of a multimeter and oscilloscope.
Multimeter Measurements
We used a digital multimeter to measure voltage, current, and resistance in our circuit. The multimeter helped us verify proper power supply voltages and check for short circuits.
- Measured VCC at 5V ±5%
- Verified continuity of all traces
- Checked resistor values before soldering
Oscilloscope Analysis
The oscilloscope allowed us to visualize signal waveforms and timing. We observed the clock signal, PWM outputs, and communication protocols like UART and I2C.
- Verified 16MHz crystal oscillator
- Analyzed button debouncing
- Checked signal integrity
Through this group assignment, I learned how essential proper test equipment is for debugging circuits. The multimeter provided quick verification of basic parameters, while the oscilloscope gave deeper insight into signal behavior and timing issues that would be impossible to diagnose otherwise.
Electronic Components
To manufacture my electronic design well, it was essential to understand the basic components used in the design process.
| Component | Unit | Schematic | Footprint | Image |
|---|---|---|---|---|
| Resistance | Ohms |  |
 |
 |
| Button | N/A |  |
 |
 |
| Microcontroller | N/A |  |
 |
 |
| Capacitor | Farad |  |
 |
 |
| LED | N/A |  |
 |
 |
Choosing the right components was crucial for my board's functionality. I learned to consider not just the electrical characteristics but also the physical footprints and availability of components. The schematic symbols represent the logical function, while the footprints define the physical connection points on the PCB.
KiCad Design Process
For this task, we relied on KiCad, an open-source electronic design tool. With it, you can create from the simplest diagrams to complex designs with considerable ease. KiCad offers a range of options to customize designs, and its built-in simulator allows you to check everything before you build it. Additionally, its 3D viewer gives a preview of what your project will look like once finished.
Step-by-Step Design
Step 1: Adding Symbol Libraries
Adding the symbols library is the first step in creating our schematic sample. Using the preferences tool at the top, I clicked on the (+) button to add my folder containing the symbol files.
Step 2: Library Configuration
Configuring the symbol library path in KiCad to include all necessary components for our design.
Step 3: Footprint Libraries
Adding footprint libraries is equally important as they guide the physical layout of components on the PCB.
Step 4: Footprint Configuration
Setting up the footprint library path to ensure all components have proper physical representations.
Step 5: Creating a New Project
Starting a new project in KiCad by clicking on File > New Project, which loads the previously configured libraries.
Step 6: Schematic Editor
The schematic editor interface where components are placed and connected to form the circuit diagram.
Step 7: Placing Components
Using the 'A' key to open the library of saved symbols and placing them in the schematic workspace.
Step 8: Connecting Components
Connecting placed components with wires using the 'X' key to establish electrical connections.
Step 9: PCB Layout
Moving to the PCB editor to arrange components and route traces based on the schematic.
Step 10: Final PCB Layout
The completed PCB layout after arranging components and routing all connections.
The schematic design phase involved selecting appropriate components and creating logical connections between them. This is the blueprint of the circuit without concern for physical placement.
Key considerations included:
- Proper power supply decoupling
- Signal flow organization
- Component compatibility
- Circuit functionality verification
The PCB layout phase transforms the schematic into a physical board design. This involved:
- Component placement for optimal signal integrity
- Trace routing considering current requirements
- Ground plane design
- Design rule checking (DRC)
I imported a DXF file from CorelDRAW to use as a board outline by going to File > Import > Graphics.
PCB Fabrication Process
After completing the PCB design in KiCad, the next step was to prepare the files for fabrication and actually mill the board.
Exporting Files
To generate files for the milling machine, I needed to convert the KiCad design to SVG format:
- In KiCad's PCB editor, I went to File > Plot
- Selected the layers to export (F.Cu, B.Cu, and User.Drawings)
- Chose SVG as the output format
- Clicked on Export to generate the files
Plot Settings
Configuring the plot settings in KiCad to export the correct layers in SVG format for PCB fabrication.
Layer Selection
Selecting F.Cu (front copper), B.Cu (back copper), and User.Drawings (board outline) for export.
Generating G-code with MODS
The SVG files were then processed using MODS to generate G-code for the milling machine:
Step 1: Accessing MODS
Right-clicking to open the page menu and selecting Programs > Machines > G-code > mill 2D PCB.
Step 2: Loading SVG Files
Loading the .SVG files generated from KiCad into MODS for G-code generation.
Step 3: Inverting Traces
Clicking the invert button and inserting traces to prepare for G-code generation.
Step 4: Calculating G-code
Generating the .nc file that the CNC machine will use by clicking the calculate button.
Milling the PCB
With the G-code files ready, the next step was to mill the PCB using a mini milling machine:
Machine Setup
Setting up the mini mill with the proper bit for PCB milling and securing the copper-clad board.
Loading G-code
Loading the .nc files into the machine control software to begin the milling process.
Milling Process
The machine carefully mills away copper to create the circuit traces according to our design.
The result of cutting my PCB - the first attempt had some imperfections but demonstrated the process well.
Soldering and Assembly
After milling the PCB, the next step was to solder all the components onto the board.
Soldering Station
Setting up the soldering iron with proper temperature control and preparing the components for assembly.
Soldering Components
Carefully placing and soldering each component, starting with the smallest and working up to larger components.
I wasn't completely satisfied with my first soldering attempt, so I tried again. The second attempt resulted in better solder joints, though I preferred the cleaner milling of the first board. This process taught me the importance of:
- Proper soldering iron temperature (around 300-350°C)
- Using the right amount of solder
- Applying flux for better joint formation
- Checking for solder bridges with a magnifier
Front view of the completed PCB
Side view showing component height
Close-up of solder joints
Final Reflections
- The complete workflow from schematic design to physical PCB
- Importance of proper component footprints
- Design considerations for manufacturability
- How to use test equipment effectively
- Troubleshooting techniques for PCB issues
- Initial difficulty with trace routing in KiCad
- Ensuring proper clearance between traces
- Debugging milling issues
- Improving soldering technique
- Time management for the complete process
This electronics design lesson has been incredibly valuable in developing my skills in PCB design and fabrication. I've gained a much deeper appreciation for the complexity involved in creating even simple circuit boards. The experience of designing a board from scratch, troubleshooting issues, and iterating on the design has given me confidence in my ability to create custom electronic solutions.
While challenging at times, particularly with the soldering and debugging aspects, overcoming these obstacles has been rewarding. I now feel equipped with practical knowledge that I can apply to future projects, including my final project for Fab Academy.
Files and Resources
| File Type | Description | Download |
|---|---|---|
| Traces SVG | SVG file containing the PCB traces | Download |
| Cut File SVG | SVG file for the board outline cut | Download |
| Traces G-code | NC file for milling the traces | Download |
| Cut G-code | NC file for cutting the board outline | Download |
