Provide explicit fab notes either in the Gerber package or as a separate fab drawing. Do not rely on fab shop defaults.
| Specification Item | Guidance / Example |
|---|---|
| Layer Count | Specify total layer count (e.g., 4-layer) |
| Material | FR-4 standard, FR-4 high-Tg (>170°C), Rogers, Polyimide, etc. |
| Board Thickness | Specify in mm or inches (e.g., 1.6mm / 0.063″) |
| Finished Copper Weight | Outer layers (e.g., 1oz); Inner layers (e.g., 0.5oz) |
| Surface Finish | HASL (lead-free), ENIG, OSP, Immersion Silver, ENEPIG |
| Solder Mask Color | Green standard; specify if blue, black, red, etc. |
| Silkscreen Color | White standard; specify if yellow or black |
| Min Trace / Space | e.g., 4/4 mil (0.1/0.1mm) |
| Min Drill (PTH) | e.g., 0.2mm finished hole |
| Via Fill / Cap | Specify if vias need tenting, plugging, or cap plating |
| Controlled Impedance | State layer, trace width, target ohms, tolerance (e.g., ±10%) |
| IPC Class | IPC-6012 Class 2 or Class 3 |
| UL Marking | Required or not — specify |
| RoHS Compliance | Specify if required for your program |