- Group Assignment
- In this group assignment, we focused on understanding and documenting the in-house PCB production process.
- Individual Assignment
- The individual task was to design, fabricate, and test a custom microcontroller development board.
Week 8. Electronics production
Group Assignment: PCB Production Process Characterization (In-House)
This report presents our group's collaborative experience in characterizing the process of fabricating printed circuit boards (PCBs) in our lab. We carefully documented key parameters such as feed rates, spindle speeds, depths of cut, and tooling setups, while also reflecting on the workflow from start to finish.
Characterization of Design Rules
| Parameter | Value |
|---|---|
| Feed Rate (X/Y) | 120 mm/min |
| Plunge Rate (Z) | 60 mm/min |
| Spindle Speed | 10,000 RPM |
| Cut Depth (Traces) | 0.1 mm |
| Cut Depth (Outline) | 0.8 mm |
| Tooling | V-bit (0.4 mm), End mill (1.0 mm) |
Workflow for PCB Manufacturing (Boardhouse)
- Create and verify the PCB design.
- Generate Gerber files and drill files from the design software.
- Validate the files using Gerber viewers.
- Submit files to a PCB fabrication service (boardhouse).
- Confirm order specifications and make payment.
- Receive and inspect fabricated PCBs upon delivery.
PCB Fabrication Process (In-House)
1. Equipment Used: Monofab SRM-20
Our team used the Monofab SRM-20 CNC milling machine, known for its precision on FR-4 or phenolic copper-clad boards. It proved ideal for our prototyping needs.
2. Initial Test Run
To ensure everything was working properly, we started with a standard test design. This allowed us to verify the basic setup and machine functionality before moving on to custom designs.
3. Calibration Design Selection
We selected specific calibration patterns from the Fab Academy library. These are designed to help verify the accuracy and alignment of the machine across small and detailed geometries.
4. Preview and Design Check
As a group, we thoroughly reviewed the PCB design in our CAD software to confirm the geometry was correct and error-free before exporting.
5. Generating Gerber and Drill Files
We exported the required Gerber files for traces and the accompanying drill files. This step was crucial for preparing the layout for the milling process.
6. File Management
All generated files were saved and organized for easy import into FlatCAM during the toolpath generation stage.
7. FlatCAM Setup
Using FlatCAM, we imported the Gerber and drill files to create toolpaths. This software allowed us to fine-tune machining parameters before generating the final G-code.
8. Reviewing in FlatCAM
We carefully examined the imported files to ensure trace alignment and correct toolpath generation.
9. Tool Selection
Our team opted for V-bit tools (typically 0.4 mm) for the trace isolation milling and a 1 mm flat end mill for the board outline.
10. Machining Parameter Configuration
We configured the CNC settings as follows: 120 mm/min feed rate, 60 mm/min plunge rate, 0.1 mm depth of cut for traces, 0.8 mm for outline cuts, and spindle speeds ranging from 8000 to 12000 RPM.
11. G-Code Generation
FlatCAM generated the final G-code files, which we saved for use in the SRM-20 milling software.
12. Machine Setup on SRM-20
We established the zero point (G54) on the material surface, ensuring alignment before starting the job.
13. Loading Files to the CNC
The previously generated G-code was loaded onto the SRM-20 interface, and we confirmed all settings matched our defined parameters.
14. Z-Axis Calibration
We carefully adjusted the tool height on the Z-axis using a manual calibration process to ensure the first layer cut through the copper surface cleanly.
15. Milling Process
The CNC milling process was initiated. Each team member took turns supervising the job, checking for consistent toolpaths and material removal.
16. Final PCB Output
The result was a clean, precisely milled PCB with accurate traces and a defined board outline, ready for component soldering.
Conclusion and Group Reflection
This project allowed us to collaboratively explore each stage of the PCB fabrication process. From design to milling, we gained hands-on experience in toolpath generation, machine calibration, and file management. We also learned to work as a team, ensuring quality control at every step and troubleshooting minor issues together. The process enhanced our understanding of digital fabrication and PCB prototyping workflows.
Week 8: Conclusion