Units
LinkCAD works with physical coordinate units throughout the conversion pipeline. Understanding how units are handled is essential for accurate conversions.
Supported Units
| Unit | Abbreviation | Relation to Meter |
|---|---|---|
| Nanometer | nm | 10⁻⁹ m |
| Micron | µm | 10⁻⁶ m |
| Millimeter | mm | 10⁻³ m |
| Centimeter | cm | 10⁻² m |
| Meter | m | 1 m |
| Mil | mil | 25.4 × 10⁻⁶ m |
| Inch | in | 25.4 × 10⁻³ m |
How Units Work
Database Units
LinkCAD’s internal database uses integer coordinates with a fixed resolution (database units). The database unit is typically 1 nanometer.
User Units
User units define the display scale. For example, with a database unit of 1 nm and user units of 1 µm, a coordinate of 1000 database units displays as 1.0 µm.
Format-Specific Units
Each format has its own unit conventions:
| Format | Typical Units | Notes |
|---|---|---|
| GDSII | nm (database), µm (user) | Defined in file header |
| DXF | Unitless | Must be specified by user |
| Gerber | Inches or mm | Defined in file header |
| CIF | 1/100 µm (standard) | Convention-dependent |
Unit Conversion
When converting between formats with different unit systems, LinkCAD handles the scaling automatically based on:
- The input file’s declared units (if any)
- The user-specified input unit interpretation
- The target output units
Example
Converting GDSII (µm) to DXF (mm):
- GDSII coordinate: 1000 µm
- DXF output: 1.0 mm
Command Line
Specify units with the --units parameter:
linkcad.exe -i chip.gds -o chip.dxf ` --units micron --quit