As a value-added option for our Assembly services, we offer Free PCB File Check, also known as Free DFM, namely we help check your PCB design file for possible issues that may affect manufacturability. If any issues were detected, we would get in touch immediately to solve the issue together, then schedule the PCB production accordingly.
The DFM will be carried out from 5 aspects: Drill Checks, Signal and Mixed Layer Checks, Power/Ground Checks, Solder Mask Checks, Silkscreen Checks. Read through the following paragraphs for more details.
1. Drill Checks
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 or ground layer in the stack. The main checklist is displayed in the following Table 1.
|Hole size||Provides a list of all PTHs, NPTHs & vias, and NPTHs that need pilot drills.|
|Hole separation||Reports duplicate holes, touching holes and close holes.|
|Missing holes||Reports missing drills for non-SMD pads.|
|Extra holes||Reports redundant drills that do not belong to any pad.|
|Reports drills touching large copper nets of more than one power or 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||Reports cases of vias not connected to at least two copper layers.|
|Reports the absence of thermals for Thru-hole pin drills and calculates the total copper area of thermal connections through all negative power, ground and mixed layers.|
2. Signal and Mixed 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. The main checklist is displayed in the following Table 2.
|Spacing||Reports spacing violations between pads, circuits and nets, and between text to text, also shorts and spacing between different CAD nets & 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. Also reports missing pads.|
|Route||Reports distance violations between edge of route features and pads, circuits, etc.|
|Size||Reports size of pads, shaved lines, text, line neckdowns, arcs and shaved arcs.|
|Sliver||Reports on slivers between lines and pads & between pads and pads. Slivers between a text feature & a functional pad will be reported, while silver between two features with the Copper Text attribute will be ignored.|
|Stubs||Reports unconnected line endpoints.|
3. Power/Ground Checks
The Power/Ground Checks are intended to find potential manufacturability defects in power, ground and mixed layers. It uses different algorithms to diagnose negative and positive power and ground layers. The main checklist is displayed in the following Table 3.
|Drill||Reports distance violation between NPTHs/PTHs/Vias to plane, copper, clearance and annular rings.|
|Silver||Reports slivers in negative and positive layers.|
|Route||Reports close spacing between copper/clearance and route features|
|Thermal||Reports spoke (tie) widths and reduction of connectivity of thermal pads.|
|NFP Spacing||Reports spacing between NFPs and NFPs, NFPs and planes.|
|Plane spacing||Reports spacing between features of different planes|
|Reports features inside/outside Keepin/Keepout areas|
|Plane width||Reports insufficient width of copper between 2 drills connected to a copper plane.|
|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. The main checklist is displayed in the following Table 4.
|Drill||Reports close distance to solder mask openings of PTH/NPTH annular rings, and where NPTH touches mask..|
|Pads||Reports close distance 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 clearance (that is, not adequately covered).|
|Route||Reports close distance between solder mask and route features.|
|Bridge||Reports different net pads without solder mask bridges.|
|Silver||Reports slivers between solder mask clearance.|
|Missing||Reports missing clearances.|
|Spacing||Reports close spacing between clearance (wider than silver).|
|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. The main checklist is displayed in the following Table 5.
|Reports close distances between silkscreen features and solder mask clearance.|
|SMD 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.|
|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 various string value.|