WEEK 08 — Electronics Production

XIAO ESP32C3 + Fiber Laser PCB Manufacturing

Week Objective

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.

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View Week 08 Assignment

1. CNC Milling Machine

  • 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
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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)
  • Speed & feed: Low feed rates required to avoid copper tearing
  • Limitations: Mechanical wear, vibration, and tool deflection affect precision

Fiber Laser (JPT 90W) Design Rules

  • Minimum trace width: ≥ 0.1 – 0.2 mm (high precision capability)
  • 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.

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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.

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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:

  1. Prepare the copper board by cleaning oxidation and residues
  2. Generate monochrome design files for laser input
  3. Select initial parameter combinations
  4. Execute engraving process
  5. Inspect traces visually using magnification
  6. Test electrical continuity and isolation
  7. 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
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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
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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.