DFM for PCB Manufacturing in China
1 resources tagged with "Dfm"
Design for Manufacturability (DFM) is the gate between your Gerber files and a Chinese fab actually being able to build your board at yield. Most Shenzhen PCB houses run a free DFM check on upload, flagging trace/space below 5 mil, annular rings under 0.15 mm, or stencil aperture ratios outside the 0.66 area-ratio rule that wrecks paste release. Catching these before tooling saves the 2-3 day back-and-forth that otherwise stretches a 5-day quick-turn into two weeks.
When you source PCBs or assembly from China, DFM is the supplier's review of whether your design respects their process capabilities — minimum trace, via, clearance, and stencil rules. The common pitfall is accepting the fab's silent auto-corrections (e.g. silkscreen shifts or pad expansions) without a marked-up confirmation, which can move test points or alter footprints.
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FAQ
Do Chinese PCB factories charge for a DFM check?
Most quick-turn fabs include a basic automated DFM review for free at quote time. A detailed engineering DFM report with annotated fixes is sometimes a paid service on complex HDI or rigid-flex boards.
What are the most common DFM failures on boards built in China?
Insufficient annular ring (drill-to-pad), trace/space below the fab's standard 5/5 mil, acid traps at acute angles, and missing or undersized fiducials for SMT placement.
How long does a DFM round take before production starts?
A clean board clears DFM in a few hours; if the fab flags issues, expect 1-3 days of email exchange to confirm corrections before tooling and panelization begin.
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