Group Assignment … on progress¶
Characterize the Design Rules for Our In-House PCB Production Process¶
Assignment Objective¶
Analyze the design rules and limitations of our in-house PCB production process using the BotFactory SV2 PCB printer to establish reliable manufacturing guidelines for future projects.
Key Tasks¶
| Task | Description | Status |
|---|---|---|
| Minimum Trace Width Test | Print varying trace widths (6-14 mil) to determine reliable minimum | ✅ Complete |
| Minimum Clearance Test | Test spacing between traces to prevent bridging | ✅ Complete |
| Ink Characterization | Document ink behavior, sintering requirements, and conductivity | ✅ Complete |
| Print Pass Optimization | Determine optimal number of passes for adequate conductivity | ✅ Complete |
| Test PCB Design | Create and print a test board with all characterization structures | ✅ Complete |
| Design Rule Table | Compile findings into a comprehensive design rule document | ✅ Complete |
Test Methodology¶
Trace Width Test Results¶
| Trace Width | Result | Conductivity | Microscope Observation |
|---|---|---|---|
| 6 mil | ❌ Failed | Open circuit | Severe ink bridging, traces merged |
| 8 mil | ⚠️ Unstable | Intermittent | Occasional bridges, inconsistent |
| 10 mil | ✅ Reliable | 1.8-3.2 Ω | Clean edges, no bridges |
| 12 mil | ✅ Excellent | 1.2-2.5 Ω | Perfect definition, robust |
| 14 mil | ✅ Excellent | 0.9-2.0 Ω | Ideal for power traces |
Minimum reliable trace width: 10 mil (0.254 mm)
Clearance Test Results¶
| Clearance | Result | Isolation | Observation |
|---|---|---|---|
| 8 mil | ❌ Failed | Shorted | Ink bridging between traces |
| 10 mil | ⚠️ Marginal | Occasional shorts | Unreliable for production |
| 12 mil | ✅ Reliable | Good isolation | No shorts, clean separation |
| 14 mil | ✅ Excellent | Perfect isolation | Recommended for dense areas |
Minimum reliable clearance: 12 mil (0.305 mm)
Process Parameters¶
| Parameter | Value | Notes |
|---|---|---|
| Machine | BotFactory SV2 | Additive inkjet PCB printer |
| Ink Type | ChemCubed C3-Ag-1037 | Ethanol-based silver nanoparticle |
| Sintering Temperature | 110°C | Continuous during printing |
| Number of Passes | 5-6 | For adequate conductivity |
| Layer Thickness | ~1-3 µm per pass | Final thickness: 10-15 µm |
| Substrate | FR4 / PET | Heat-resistant material required |
| Nozzle Test | ✅ Required before each print | Verify all jets firing |
Design Rule Table¶
| Parameter | Recommended Value | Critical for XIAO ESP32-C3 |
|-----------|-------------------|----------------------------|
| **Minimum Trace Width** | **10 mil (0.254 mm)** | ⚠️ Essential for dense pins |
| **Minimum Clearance** | **12 mil (0.305 mm)** | ⚠️ Essential for dense pins |
| Minimum Pad Size | 1 mm | ✅ Sufficient |
| Minimum Drill Diameter | 0.6 mm | For mechanical drilling |
| **Heat Bed Temperature** | **110°C** | ✅ Verified |
| **Printing Passes** | **5–6** | ✅ Verified |
| Ink Curing | Continuous sintering | During printing |
Test PCB Documentation¶
 Complete test PCB |
 Trace width test pattern |
 Clearance test pattern |
 10 mil trace - successful |
 8 mil trace - bridging failure |
 XIAO footprint inspection |
Group Assignment Resources¶
| Resource | Link |
|---|---|
| Full Group Assignment Documentation | week08_group_assignment_complete.md |
| Test PCB Design Files | design_files/test_pcb/ |
| Gerber Files | gerbers/test_pcb/ |
| Raw Data & Measurements | data/trace_width_test.csv |