Most DFM questions are avoidable. These are the values we check on every order — design to them and your quote, fabrication and assembly will move without rework.
Fabrication rules
| Feature | Minimum / recommended |
|---|---|
| Trace width / spacing | 4 / 4 mil standard; 3 / 3 mil on HDI with process review |
| Annular ring | 0.15 mm minimum; 0.20 mm preferred |
| Minimum drill | 0.15 mm mechanical; 0.075 mm laser microvia |
| Aspect ratio | 10:1 standard; 12:1 reviewed |
| Solder mask clearance | 0.1 mm per side minimum; 0.15 mm preferred |
| Solder mask dam | 0.1 mm minimum between pads |
| Board thickness | 0.2 mm - 6.0 mm |
| Copper to board edge | 0.3 mm minimum; 0.5 mm preferred |
| Plated hole to copper | 0.25 mm minimum |
| Silkscreen line width | 0.15 mm minimum; 0.2 mm preferred |
Panel and assembly considerations
- PanelizationLeave 5-10 mm rails for handling. Confirm the panel size against our 520 x 620 mm maximum.
- FiducialsAdd three global fiducials, 1 mm copper dot with 2 mm clear area, outside the component area.
- Tooling holesTwo or three 2.0-3.0 mm non-plated holes in the rails for assembly fixtures.
- ImpedanceState the target and tolerance in the fab notes; we will propose the stack-up and coupons.
- Edge clearanceKeep components at least 3 mm from the board edge unless the assembly drawing says otherwise.
What we check in DFM review
We compare your Gerber, drill and drawing against our process window, then report anything that could affect yield, reliability or assembly. The report is descriptive, not a redesign: you decide which suggestions to accept. Typical findings include insufficient annular ring, solder mask slivers, missing solder mask between fine-pitch pads, unsupported via-in-pad, and panel features that fall outside the handling area.
A clean DFM review is not a guarantee that the design works — it confirms the board can be built repeatably. Electrical, thermal and mechanical validation remain part of your design process.
Frequently asked questions
What happens if my design is outside the rules?
We quote an exception with the process change and any cost impact. Nothing is changed without your approval.
Can you panelize my board?
Yes. We propose a panel based on board size, quantity, assembly method and material utilization.
Do you charge for DFM review?
No. DFM review is included with every quote and order.