PCB DFM (Design for Manufacturability) check aims to indicate the design’s non-conformance with manufacturing requirement. Circuit designers tend to know little about manufacturing and some points described in design file may not be totally compatible with manufacturing requirement. More significantly, DFM check can help reducing potential issues that may cause defects in manufacturing process, improving products’ reliability.
The Drill Checks action is intended to find potential manufacturability defects in drill layers (through, buried and blind via layers) and generate statistics on drill layers. It is intended to operate only on drill layers. It uses the drill layer, the top and bottom layers of its drill stack and any power/ground layer in the stack.
Main Checklist: ● Hole Size—provides a list of all PTHs, NPTHs, and vias, as well as NPTHs that need pilot drills. ● Hole Separation—reports duplicate holes, touching holes and close holes. ● Missing Holes—report missing drills for non-SMD pads. ● Extra Holes—report redundant drills that do not belong to any pad. ● Power/Ground Shorts—report drills touching large copper nets of more than one power/ground layer. ● NPTH to Route—reports drills that have the Tooling Hole or Mounting Hole attributes, and NPTHs that are close to the route path. ● Stubbed Vias—report cases of vias not connected to at least two copper layers. ● Thermal Connection—reports the absence of thermals for through-hole pin drills and calculates the total copper area of thermal connections through all negative power/ground and mixed layers.
2. Signal Layer Checks This function is intended to find potential manufacturability defects in signal layers and mixed layers and generate statistics. The action can operate on any layer, but is mainly intended for signal layers. It uses the layer itself and any NC (drill or route) layer which pierces it.
Parameters * Spacing: Defines search radius to use when looking for closely spaced features. * Drill to Copper: Defines the search radius to use when looking for copper features that are closer to drills, also determines the maximum annular ring values that will be reported. * Route to Copper: Defines the search radius to use when looking for copper features that are close to the center-line (skeleton) of route elements. * Sliver min: Maximum sliver width to be reported in the sliver category.
Main Checklist： ● Spacing—reports spacing violations between pads, circuits and nets, and between texts. It also reports shorts and spacing between different CAD nets and close distances between non-touching features on the same CAD or layer nets. ● Drill—reports distance violations between NPTHs/PTHs/Vias, and pads, circuits, annular rings and copper. It also reports missing pads. ● Route—reports distance violations between edge of route features and pads, circuits, etc. ● Size—reports sizes of pads, shaved lines, text, line neckdowns, arcs and shaved arcs. ● Sliver—reports on slivers between lines and pads or between pads. Slivers between two features with the Copper Text attribute are ignored. However, a sliver between a text feature and a functional pad is reported. ● Stubs—report unconnected line endpoints. 3. Power/Ground Checks The Power/Ground Checks are intended to find potential manufacturability defects in power and ground planes, and mixed layers. It uses different algorithms to diagnose negative and positive power and ground layers.
Parameters * Drill to Copper: Maximum search radius for all drill-related measurements. * Minimal Sliver: Minimum allowable sliver width. A sliver narrower than this value will be reported. * Route to Copper: Search distance for copper to route measurements. * NFP Spacing: Search distance for NFP spacing measurements. * Plane Spacing: Search distance for split plane spacing measurements.
Main Checklist： ● Drill—reports distance violations between NPTHs/PTHs/Vias to plane, copper, clearances and annular rings. ● Sliver—reports slivers in negative and positive layers. ● Route—reports close spacing between copper/clearances and rout features. ● Thermal—reports spoke (tie) widths and reduction of connectivity of thermal pads. ● NFP Spacing—reports spacing between NFPs to NFPs, and NFPs to planes. ● Plane Spacing—reports spacing between features of different planes. ● Keepin/Keepout Areas—report features inside/outside Keepin/Keepout areas. ● Plane Width—reports insufficient width of copper between two drills connected to a copper plane. ● Plane Connection—reports disconnected areas of copper often used as reference planes that are left in a design could cause an unreferenced critical net, or a missing electrical connection.
4. Solder Mask Checks This function checks Solder Mask layers for potential manufacturability defects. Solder Mask layers are always assumed to be negative, that is, all positive features describe clearance or the absence of solder masks. This action also checks if solder paste has been deposited on all SMD pads. The action operates on a single Solder Mask layer per side at a time. If more than one SMD is selected, the action will not work.
Parameters * Spacing min: Defines search radius for closely-spaced features. * Solder Mask Annular Ring: Defines search radius for close to solder mask annular rings. * Sliver min: Reports sliver of solder masks. * Solder mask coverage: Reports circuit features too close to solder masks. * Solder mask to rout: Reports close distance between rout features and solder mask clearances. * Tests List: Defines the tests that will be run. * Compensated Rout: Yes - enables measurements to internal cutout of compensated rout feature. No - measures to skeleton.
Main Checklist： ● Drill—reports close distances to solder mask openings of PTH/NPTH annular rings, and where NPTH touches mask. ● Pads—reports close distances to solder mask openings of all pads, including undrilled pads. It also reports on a special group, Gaskets, which reports the width of solder mask overlap on features. ● Coverage—reports lines too close to clearances (that is, not adequately covered). ● Route—reports close distances between solder mask and route features. ● Bridge—reports different net pads without solder mask bridges. ● Sliver—reports slivers between solder mask clearances. ● Missing—reports missing clearances. ● Spacing—reports close spaces between clearances (wider than sliver). ● Extra—reports solder mask features which lack copper pads, or do not intersect with copper.
5. Silkscreen Checks This function is intended to find potential manufacturing defects in silkscreen layers and generate statistics. The check operates only on silk screen layers because it relies on the job matrix to find the related external copper, solder mask and drill layers against which to check.
Parameters * Spacing: Defines the search radius to use when looking for closely-spaced features. * Compensated Route: Yes - enables measurements to internal cutout of compensated route feature.
Main Checklist： Solder Mask Clearance—reports close distances between silkscreen features and solder mask clearances. SMD (Surface Mount Device) Clearance—reports close distances between silkscreen features and SMD pads. Pad Clearance—reports close distances between silkscreen features and pads. Hole Clearance—reports close distances between silkscreen features and drills. Route Clearance—reports close distances between silkscreen features and route features. Line Width—reports line width violations and length to width ratio violations. String Overlap—reports the touching or intersection of silkscreen features of different string value.