10 rules for manufacturing-friendly PCB design – avoid errors, save costs.
What is DFM?
DFM (Design for Manufacturing) means designing the PCB layout so that it can be manufactured error-free and cost-effectively. Good DFM saves money and increases quality.
The most common manufacturing problems arise from layout errors that could have been avoided during design. A DFM review before ordering is therefore indispensable.
The 10 DFM Rules
- Correct pad sizes: Pads must match the component footprint. Pads too small = poor solder joints, too large = risk of solder bridges. Use IPC-7351 as a reference.
- Maintain minimum clearances: At least 0.2mm between SMD pads, 0.3–1.0mm between components depending on size. Too-tight placement hinders inspection and rework.
- Place fiducials: At least 3 fiducial marks on the board (2 global + 1 local for fine-pitch). Diameter 1.0mm with 2.0mm keep-out zone.
- Solder mask openings: Solder mask must be correctly defined. Standard: pad + 0.05mm per side. For fine-pitch, consider using Solder Mask Defined (SMD) pads.
- Thermal relief pads: Connect pads to copper planes with thermal relief – otherwise heat dissipates during soldering and the joint becomes cold.
- Component orientation: Place similar components in the same direction (consistent polarity marks). This simplifies inspection and reduces placement errors.
- Provide test points: Accessible test points for ICT and functional testing. At least 1.0mm diameter, not hidden under components.
- Panel design: For small boards: design panels with V-score or routing. At least 5mm edge clearance for the placement machine.
- Assembly drawing: Clear assembly side, component polarity, and reference designators. Helps with manual assembly and quality control.
- Prevent tombstoning: For small passive components (0402, 0603): symmetric trace routing to both pads, equal copper area under both pads.
DFM Check Before Ordering
Before sending your design to manufacturing, check the following:
- Visually inspect Gerber data (e.g., with KiCad Gerber Viewer)
- Verify BOM against footprints
- Generate and review the pick & place file
- Verify minimum clearances and pad sizes
- Are fiducials and tooling holes present?
Many EMS partners like SMTEC AG offer a free DFM review as part of the quotation process.
Ready for your PCBA project?
SMTEC AG manufactures prototypes and series – fast, flexible and of the highest quality.
Request a quote →
