DFM review is included on every order, and it is not a formality — it is a fixed checklist of the failure modes that actually scrap panels. This is the list, so you can pre-check before sending Gerbers.
The twelve checks
- annular ring against layer count and drill tolerance — the single most common first-article rejection.
- Trace/space vs copper weight — 2/2 mil is a 1 oz figure; etch undercut widens the rule on 3 oz and above.
- aspect ratio — board thickness divided by the smallest drill; 8:1 standard, 20:1 with process controls, 25:1 backplane-class.
- Copper-to-edge clearance — 0.30 mm minimum unless edge plating is specified.
- Thermal-relief spokes on plane connections to vias and pads — solid connections on big planes make hand soldering impossible and reflow profiles unreliable.
- Solder-mask dams between fine-pitch pads — below a certain pitch the dam cannot be held and the pads must be mask-free by design.
- silkscreen over pads and vias — the classic self-inflicted assembly defect; we check it even when the fab drawing does not.
- Panelisation and depaneling — tab-route vs V-score vs edge rail; width, fiducials, and whether a router or a V-scoring line depanels it.
- impedance reference planes — every controlled trace needs an unbroken reference beneath it; we check plane splits before quoting tolerance.
- Via-in-pad — flagged for fill-and-cap unless tented vias are explicitly acceptable under the part.
- Paste layer vs footprint — aperture ratio and home-plate adjustments for reflow yield, checked at assembly handoff.
- Balanced copper distribution across the panel — asymmetric copper warps boards in reflow; we may add thieving or ask for a stackup change.
What DFM costs you
Nothing if it passes, a day if it flags a real problem. What skipping it costs: a scrapped panel and a slipped schedule. The asymmetry is the whole point — it is much cheaper to change a Gerber file than to scrap a panel.
How to make the review fast
- Send the stackup intent (layer count, target impedances, copper weights) with the Gerbers, not after.
- State the finish and any press-fit or wire-bond requirements up front — they change which checks matter.
- If the design is cost-sensitive, send the outline early so panelisation can be evaluated before layout freezes.
Questions we get about this
Does DFM review cost extra or delay my order?
It is included on every order and costs nothing when it passes. If it flags a real problem, deciding and revising typically adds about a day — far less than scrapping a panel.
What is the most common DFM rejection?
Insufficient annular ring relative to layer count and drill tolerance — it accounts for the largest share of first-article rejections.
Can I run DFM myself before sending Gerbers?
Yes — the checklist on this page is the same list our engineers run. Twelve checks cover the failure modes that actually scrap panels.