This week focused on understanding the complete workflow of PCB fabrication, from the conceptual electronic design to the validation of a fully functional embedded system.
The main goal was not only to fabricate a PCB but to understand how fabrication parameters directly affect electrical performance. A 50W fiber laser machine was used as an alternative manufacturing method, replacing traditional CNC milling or chemical etching processes.
This required developing an understanding of digital manufacturing processes, thermal material behavior, and iterative experimentation.
GROUP ASSIGNMENT — Fiber Laser PCB Characterization
The group assignment consisted of analyzing and characterizing the fabrication capabilities of a 50W fiber laser machine when applied to PCB production.
PCB Manufacturing: Dual Technology Approach
In this assignment, PCB fabrication will be explored using two complementary manufacturing technologies:
CNC milling with a high-speed spindle and fiber laser machining. The goal is to compare precision, speed,
and manufacturing constraints of each method.
Process: Subtractive manufacturing using rotating cutting tools
Tooling: V-bits and micro end mills (0.2–0.8 mm typical)
Precision: Medium to high (depends on calibration and tool wear)
Strengths: Good for rapid prototyping and multilayer isolation routing
Limitations: Tool wear, mechanical vibration, and minimum trace width constraints
2. Fiber Laser Machine (JPT 90W)
Technology: Fiber laser marking and ablation system
Power: JPT laser source, 90W
Process: Non-contact material removal using high-energy laser beam
Precision: Very high (excellent for fine traces and micro-patterns)
Strengths: No tool wear, high repeatability, clean edges
Limitations: Material sensitivity, heat effects, and higher setup cost
Objective
Both technologies will be evaluated to determine their effectiveness in PCB fabrication,
focusing on resolution, reliability, and workflow efficiency.
PCB Design Rules: CNC & Fiber Laser Manufacturing
This section defines the minimum design constraints and fabrication rules for producing PCBs
using two in-house technologies: CNC milling and JPT 90W fiber laser. These rules ensure
manufacturability, reduce errors, and improve repeatability in the production process.
CNC Milling Design Rules
Minimum trace width: ≥ 0.4 mm (recommended 0.5 mm for reliability)
Minimum isolation gap: ≥ 0.4 – 0.6 mm depending on tool diameter
Tool diameter: 0.2 mm – 0.8 mm V-bit or micro end mill
Cut depth per pass: 0.05 – 0.2 mm (avoid tool breakage)
Material flatness: Must be perfectly leveled (critical for isolation routing)
Minimum spacing: ≥ 0.15 – 0.25 mm depending on energy settings
Power range: Adjustable (JPT 90W, optimized per material)
Process type: Non-contact ablation (no mechanical stress)
Heat affected zone: Must be controlled to avoid substrate damage
Surface requirement: Clean, flat copper surface for consistent engraving
Limitations: Sensitive to material reflectivity and thermal distortion
These rules define the baseline for PCB layout design before fabrication. Proper adherence ensures
higher yield, reduced iteration cycles, and compatibility with both CNC and laser manufacturing workflows.
Machine and Process Description
PCB Test Production: Trace Fabrication Trial
We used the provided drawings for the traces to generate a controlled fabrication test.
The objective was to evaluate resolution, precision, and repeatability in both CNC milling
and fiber laser processes under real manufacturing conditions.
CNC Milling Process
Import of trace drawings into CAM software
Toolpath generation for isolation routing
Selection of V-bit tool (0.2–0.4 mm tip)
Material leveling and fixturing of copper board
Execution of milling with controlled feed and depth
Cleaning and inspection of trace quality
Fiber Laser (JPT 90W) Process
Import of vector trace design into laser software
Parameter setup (power, speed, frequency)
Focus calibration of JPT 90W fiber laser
Non-contact ablation of copper layer
High-resolution engraving of fine traces
Final cleaning and inspection under magnification
This comparative test highlights the differences between subtractive CNC milling and
non-contact fiber laser machining, focusing on precision, repeatability, and fabrication efficiency.
The fiber laser machine operates by emitting high-frequency pulses of energy that remove copper from the PCB surface through thermal ablation. This process is entirely contactless and controlled digitally.
Unlike milling, there is no mechanical force applied to the board. However, the process introduces thermal energy that can affect both the copper layer and the substrate.
Critical parameters:
Laser Power: Controls energy intensity
Speed: Determines exposure time
Frequency: Defines pulse density
Number of passes: Controls depth and precision
Understanding the interaction between these variables is essential for achieving reliable PCB results.
Test Board and Experimental Strategy
A test PCB was designed to explore the limits of the fabrication process. This board included a range of geometries to evaluate resolution, spacing, and engraving quality.
The experimentation followed a structured iterative process:
Prepare the copper board by cleaning oxidation and residues
Generate monochrome design files for laser input
Select initial parameter combinations
Execute engraving process
Inspect traces visually using magnification
Test electrical continuity and isolation
Adjust parameters and repeat
This process was repeated multiple times to ensure consistent results and identify optimal fabrication conditions.
Results
PCB Test Results: CNC vs Fiber Laser
This section summarizes the results obtained from the PCB trace fabrication tests using
two different manufacturing technologies: CNC milling and JPT 90W fiber laser. The comparison
highlights performance differences, advantages, and limitations observed during the process.
CNC Milling Results
Pros
Accessible and widely available fabrication method
Good for rapid prototyping and iterative testing
Works with standard PCB copper boards without special coating
Easy integration with CAM workflows (e.g., FlatCAM, Fusion 360)
Cons
Tool wear affects precision over time
Limited resolution due to mechanical constraints
Requires careful leveling of the material
Risk of trace breakage or inconsistent isolation paths
Fiber Laser (JPT 90W) Results
Pros
High precision and excellent trace definition
No physical contact → no tool wear
Fast processing for detailed micro-patterns
High repeatability and consistency
Cons
Higher setup complexity and parameter tuning required
Sensitive to material reflectivity and surface condition
Thermal effects may damage fine features if not controlled
Equipment cost is significantly higher than CNC milling
Overall, CNC milling is more practical for fast prototyping and educational environments,
while fiber laser machining provides superior precision and repeatability for advanced PCB fabrication.
INDIVIDUAL ASSIGNMENT — LED Roulette PCB
The individual assignment focused on applying the characterized process to fabricate a functional PCB capable of producing a LED roulette animation using a XIAO ESP32C3.
Bill of Materials
Component
Quantity
Description
XIAO ESP32C3
1
Main microcontroller
LEDs
7
Visual output
Resistors 220Ω
7
Current limiting
Copper PCB
1
Base material
Step 1 — Schematic Design (KiCad)
The design process began with the creation of a schematic in KiCad. This stage defines the logical structure of the circuit.
Each LED was connected to a dedicated GPIO pin from the XIAO ESP32C3 through a 220Ω resistor. This ensures proper current limiting and protects both the LED and the microcontroller.
Special attention was given to:
Correct LED polarity (anode and cathode)
Selection of GPIO pins capable of digital output
Clear and organized schematic layout
Electrical Rule Check (ERC) was executed to detect connection errors before proceeding.
Step 2 — PCB Layout Design (KiCad)
After validating the schematic, the design was transferred to the PCB editor.
Components were placed with a clear intention: LEDs arranged in a circular geometry to visually simulate a roulette effect.
Routing required careful planning:
Minimize trace length to reduce resistance
Avoid crossing traces
Maintain consistent spacing for laser fabrication
Ensure accessibility for soldering
The design rules obtained in the group assignment were strictly followed to ensure manufacturability.
Step 3 — File Preparation in Inkscape
The PCB layout was exported and processed in Inkscape to generate a file compatible with the fiber laser.
This step is critical because the laser interprets graphical information directly.
Detailed process:
Export traces from KiCad as SVG
Open file in Inkscape
Convert all traces to pure black color
Ensure background is white
Remove labels, dimensions, and unnecessary layers
Convert strokes into filled paths
Check for line continuity
Export final file
Any graphical error at this stage results in fabrication defects.
Image Processing and G-code Generation using Fab Modules (Mods)
For this project, Fab Modules (Mods) were used to process the PCB design images and generate the corresponding G-code required for digital fabrication. This step is critical because it translates visual design data into machine instructions.
The workflow in Mods follows a modular structure where each node processes specific information. The objective was to convert a monochrome PCB image into precise toolpaths that define how the machine removes copper.
Detailed Process
Open Mods in a web browser (local or online version)
Select the program: PCB → mill traces (1/64) or equivalent depending on machine
Load the PNG image exported from KiCad or Inkscape
Verify image resolution and scale (DPI must match design)
Adjust threshold if necessary to ensure clean black/white separation
Define tool diameter according to fabrication method
Configure cut depth and max depth
Set offset number (number of passes around traces)
Adjust step-over for precision
Define feed rate (speed of tool movement)
Set spindle speed or equivalent parameter (if required)
Generate toolpath preview
Inspect for errors such as disconnected traces or unwanted cuts
Calculate toolpath
Export G-code file
Important Considerations
The image must be strictly black and white (no grayscale)
Incorrect DPI leads to scaling errors in the final PCB
This project demonstrated that PCB fabrication is not only a design challenge but also a manufacturing challenge.
The fiber laser method offers flexibility and speed, but requires precise calibration and understanding of thermal effects.
The integration of all stages resulted in a functional and well-documented embedded system.
Conclusion
This assignment demonstrated the complete workflow of PCB fabrication, integrating design, manufacturing, and programming into a single process. The use of a fiber laser introduced a non-traditional method that required careful parameter calibration and a deep understanding of thermal effects on materials.
Through iterative testing, it was possible to establish reliable design rules and validate the feasibility of this fabrication method. The integration of tools such as KiCad, Inkscape, and Fab Modules (Mods) ensured a consistent transition from digital design to physical implementation.
The final result, a fully functional LED roulette controlled by the XIAO ESP32C3, confirms that the workflow was successful. This process reinforced the importance of precision, testing, and multidisciplinary integration in digital fabrication.
Final Checklist — Electronics Production Assignment
✔ Designed a complete PCB using electronic design software (KiCad)
✔ Created and validated the schematic (ERC check completed)
✔ Designed PCB layout following fabrication constraints
✔ Applied design rules obtained from group assignment
✔ Exported PCB design to SVG/PNG format correctly
✔ Processed design files in Inkscape (clean black/white, vector preparation)
✔ Used Fab Modules (Mods) to generate toolpaths and G-code
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