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Section 11: SMT Assembly Defects
August 11, 2010 |Estimated reading time: 2 minutes
These images of SMT defects and attributes were compiled by consultant Tom Clifford. Section 11 includes images of bridges, tombstoning, dead-shorts, "type G" defects and more.
These images of SMT defects and attributes provide resources for training, quality control specs and standards and research. Other Sections, published and upcoming, are listed below the gallery. Descriptions, provided below each image, do not necessarily define causality or severity, but serve only as identification.Figure 1: Lead-on-land (~30%).Figure 2: "Sweep" bent fingers, separation violation.
Figure 3: Solid bridge.
Figure 4: Unknown bridge, probably metallic. Might not be a dead-short now, but will fail later.Figure 5: Odd erupted via-fill situation, resulting in extreme stand-off of attached SMR.Figure 6: Compromised joint: Solder on lead is not wetted to solder on pad. Might test okay, but will not be reliable.
Figure 7: Type G" defect. Solder did not wet to end-cap of SMC.Figure 8: "Type G" defect. No solid solder connection. Might test okay, but will not be reliable.
Figure 9: Copper wire bridge. Source at printing or on incoming bare-board.Figure 10: Fiber debris. If metallic: Dead short; if non-conductive: Probably high-resistance short.Figure 11: Unknown fiber contaminant. Possibly loose enough to wash off, if not: Trouble.Figure 12: Unknown bridging particulate FOD--assume the worst.
Figure 13: "Tombstoned" SMR.
Figure 14: Misplaced SMC.
Figure 15: "Type G" or "head-in-pillow" defect. Solder does not wet both surfaces.
Figure 16: "Type G" defect.
Figure 17: Nominal gull-wing (probably fine-pitch) solder joint.Figure 18: Nominal SMC solder joint. Note: Fairly common small voids.Figure 19: Nominal J-lead solder joint.
Figure 20: Nominal SMR. Note: Every planar, unconstrained SMT component produces a ~1 mil solder-film thickness.
Figure 21: Excess solder, gull-wing.
Figure 22: Excess solder, SMD.
Figure 23: SMR with a couple of voids.
Figure 24: Starved J-lead. Note: Again, every planar unconstrained solder-joint (excess or starved) yields a ~1 mil solder-film thickness.
Figure 25: Solder-splash, possible bridge, likely isolation gap violation.
Figure 26: Bent-up-off-plane lead, no solder contact.
Figure 27: Top view of "snaggle-tooth" condition. Looks like a damaged fine-pitch gull-wing, clumsily "repaired," prior to placement. Might pass electrical-test, but will not be reliable, long-term.
Section 1. BGA PCB Defects, Plating
Section 2. BGA PCB Defects, External Damage
Section 3: BGA PCB Defects, Via-in-Pad
Section 4: BGA PCB Defects, Dimensions, Poke-Thru
Section 5: BGA PCB Defects, Mask
Section 6: BGA PCB Defects, Metallic Contamination
Section 7: BGA Pads--Non-Metallic ContaminationSection 8: BGA PWB-Related Assembly DefectsSection 9: BGA Assembly X-Sections
(Upcoming)Section 12: SMT Assemblies, T-Cycled CracksSection 13: SMT PWB PadsSection 14: PWB Vias, X-Sections
Do you have images of solder-joint or other interconnect features or defects that you would want to share? Send them to Holly Collins at SMT, editorial@iconnect007.com. You must obtain permission to publish the photos and may not show proprietary or company-specific information on the images. We are particularly interested in images of advanced SMT assembly technologies and failure analyses.