Design for Manufacturing (DFM) Checklist Before Sending Gerbers to a Fab
The design decisions that determine whether your board fabricates cleanly the first time, or comes back with a list of exceptions.
Why DFM matters before submission
Most fabrication issues aren't caught because a board was designed incorrectly in a functional sense, they're caught because it was designed without the fab's actual process capabilities in mind. A schematic can be electrically perfect and still be expensive, slow, or impossible to build at the layout stage.
Design for Manufacturing (DFM) is the practice of checking a layout against real fabrication and assembly constraints before submission, not after a fab's engineering review flags it. Catching an issue at review stage costs a design revision and a delay. Catching it during layout costs nothing but attention.
Trace width, spacing, and copper-to-edge clearance
Every fab publishes minimum trace width and spacing for their standard process, commonly 4mil/4mil or 6mil/6mil depending on the shop and the layer. Designing tighter than your fab's standard capability pushes the board into an advanced or prototype-only process tier, which usually means higher cost and longer lead time for no functional benefit.
Copper-to-board-edge clearance is a related, often-missed rule. Copper features placed too close to the board outline risk being cut into during profiling or routing, especially on panels that get V-scored or tab-routed. A consistent 0.3mm to 0.5mm keep-out from the edge avoids this entirely.
Vias, drill sizes, and aspect ratio
Via aspect ratio, the board thickness divided by the drill diameter, determines whether plating can reliably reach the bottom of the hole. A standard fab can typically handle up to about 8:1 to 10:1 without moving to a specialized process. On a 1.6mm board, that means a 0.2mm drill is well within normal capability; a 0.1mm drill on the same board is pushing into a different cost tier.
Microvias and blind/buried vias are sometimes necessary for dense designs, but they should be a deliberate decision, not an accident of routing density. Each one adds a process step and a cost line.
Silkscreen and solder mask rules
Silkscreen printed over exposed copper or pad edges doesn't adhere properly and can flake into the assembly process. Keep silkscreen text and markings clear of pads with a small margin, and keep minimum text height above what your fab's printer can actually resolve, usually around 0.8mm to 1mm for clean legibility.
Solder mask slivers, thin strips of mask between closely spaced pads, are a common review flag. If mask dam width falls below the fab's minimum (commonly 0.1mm to 0.15mm), the mask can lift during reflow. Widening pad-to-pad spacing or removing mask between pads that don't need isolation both resolve it.
Panelization and assembly considerations
If the board is small enough to be panelized for assembly, decide on V-scoring or tab-routing (with mouse bites) early, since it affects keep-out zones and how close components can sit to the panel breakout line. Fiducial markers, at least two per panel and ideally two per individual board on dense assemblies, are what let pick-and-place equipment register accurately; a board without them may need to be placed manually, adding cost.
Component courtyards, the clearance zone around each part reserved for the placement nozzle, matter more on panels than single boards, since placement machines run the whole panel in one pass.
The file checklist: what to actually send
A complete submission is what prevents a fab from guessing, or worse, building to an assumption. At minimum: Gerbers for every copper, mask, and silkscreen layer; drill files with a matching drill legend; a pick-and-place (centroid) file if the fab is assembling; a BOM with manufacturer part numbers, not just values; and a fabrication drawing calling out board thickness, stack-up, surface finish, and any impedance-controlled nets.
Running a design rule check (DRC) against the fab's specific rule set before export catches the majority of these issues automatically. It's a five-minute step that replaces a week of back-and-forth with a fab's engineering team.
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