Automating PCB Design Workflows with Python Scripting: A Step-by-Step Guide

Printed Circuit Board (PCB) design is a cornerstone of electronics engineering. From prototype development to high-volume production, PCBs are at the heart of every electronic device. However, manual PCB design processes—especially those involving repetitive layout configurations, rule checking, or component placement—can be time-consuming and error-prone.

This is where Python scripting comes in. By automating various tasks in PCB design, engineers can speed up development, reduce human error, and improve design consistency. Most modern PCB EDA (Electronic Design Automation) tools, such as KiCad, Altium Designer, and EAGLE, offer APIs or scripting interfaces compatible with Python.

In this article, we’ll explore how Python can be used to automate PCB design workflows with practical examples, tools, and FAQs to help you get started.

1. Why Automate PCB Design?

Automation in PCB design solves several real-world issues:

✅ Faster iteration for complex or repeated designs
✅ Reduced manual errors in placement and routing
✅ Consistency across design teams
✅ Rule-based automation for DRC (Design Rule Checks)
✅ Seamless BOM generation and manufacturing outputs
✅ Easy parametric design changes

Automation is not just for large-scale manufacturers; even hobbyists and small design teams can benefit.

2. Overview of EDA Tools Supporting Python

EDA Tool	Python Support	Type
KiCad	Yes (via `pcbnew` API)	Open-source
Altium Designer	Yes (via scripting server)	Proprietary
EAGLE	Limited (via ULP scripting, not pure Python)	Proprietary
EasyEDA	Limited (cloud API access)	Freemium

🔧 Note: KiCad offers the most robust Python API out-of-the-box, making it ideal for automation.

3. Python Scripting in KiCad: A Primer

KiCad's scripting interface is built into its pcbnew layout editor and exposes access to:

Modules (footprints)
Tracks and vias
Layers
Netlist and components
Board dimensions

🛠 Example: Load and Inspect a PCB File

import pcbnew

board = pcbnew.LoadBoard("my_project.kicad_pcb")
print("Number of footprints:", len(board.GetFootprints()))

This script loads a .kicad_pcb file and counts the number of footprints on the board.

4. Common Automation Tasks in PCB Design

Here are common use cases for Python in PCB workflows:

🔹 1. Automatic Component Placement

Place components relative to each other using coordinate rules.

for footprint in board.GetFootprints():
    if "R" in footprint.GetReference():
        footprint.SetPosition(pcbnew.wxPointMM(50, 50))

🔹 2. Batch Renaming or Labeling

Apply naming schemes to silkscreen text or net labels.

🔹 3. Rule-Based Layout Checks

Perform DRC checks on spacing, trace widths, or via clearances using Python logic.

🔹 4. Netlist Parsing and Manipulation

Modify or validate net connectivity before routing.

🔹 5. Batch Gerber Generation

Automate the export of Gerber and drill files with standardized naming.

plot_controller = pcbnew.PLOT_CONTROLLER(board)
plot_controller.OpenPlotfile("TopLayer", pcbnew.PLOT_FORMAT_GERBER, "Top layer")

🔹 6. BOM (Bill of Materials) Automation

Generate a BOM with custom filters (e.g., exclude test points).

5. Sample Python Automation Scripts

📌 Script: Align All Capacitors Along a Grid

import pcbnew

board = pcbnew.LoadBoard("example.kicad_pcb")
x_offset = 30 * 1e6
y_base = 50 * 1e6
gap = 5 * 1e6

index = 0
for fp in board.GetFootprints():
    if fp.GetReference().startswith("C"):
        fp.SetPosition(pcbnew.VECTOR2I(x_offset + index * gap, y_base))
        index += 1

pcbnew.SaveBoard("output.kicad_pcb", board)

📌 Script: Highlight Violated Nets

for net in board.GetNetsByName():
    if net.GetNet().GetLength() > 5000000:  # 5 meters in internal units
        print(f"Warning: {net.GetNetname()} exceeds recommended length")

6. Integration with BOM, DRC, and Manufacturing

Python can extend your PCB design process beyond layout:

BOM generation: Use pandas to create filtered Excel/CSV files
DRC scripting: Define custom rules and flag violations
Version control: Auto-commit changes to Git with scripts
3D Modeling: Export footprint locations for enclosure integration

Example: Generate a BOM in .xlsx

import pandas as pd

data = {"Reference": ["R1", "C1"], "Part Number": ["10K", "100nF"]}
df = pd.DataFrame(data)
df.to_excel("BOM.xlsx", index=False)

7. Benefits and Limitations

✅ Benefits:

Scales well for large projects
Saves time and reduces fatigue
Encourages reusability of design blocks
Supports design for manufacturing (DFM)

⚠️ Limitations:

Learning curve for APIs
Scripting access may vary between EDA tools
Debugging can be complex without UI feedback

8. FAQs

Q1: Which EDA tool is best for Python automation?

KiCad is currently the best for open-source Python scripting. Altium has scripting capabilities but requires licensing and COM server setup.

Q2: Can I write routing algorithms with Python?

Yes, but it’s complex. You can place vias and tracks, but full autorouting requires geometric algorithms and constraint solvers.

Q3: Is this only useful for large PCBs?

No! Even small boards benefit from automated component placement, BOM generation, and design checking.

Q4: Can I automate schematic capture?

KiCad v6+ allows some schematic automation via schematic APIs, though it's less mature than layout scripting.

Q5: What skills do I need to start?

Basic Python skills and familiarity with your EDA tool’s scripting environment. No need to be an expert in Python to automate repetitive tasks.

9. Conclusion

Python scripting for PCB design automation is a game-changer for engineers. It enables you to build faster, smarter, and more reliable designs with minimal repetitive effort. Whether you're working on hobby electronics or high-volume manufacturing, automating your PCB workflow with Python gives you a competitive edge.

Start small: write a script that moves all resistors to a grid or generates your BOM automatically. Over time, build a library of reusable scripts to streamline your design process.

Prasun Barua