Integrating IEEE 1149.1 Boundary Scan with Flying Probe Target Vectors
Integrating IEEE 1149.1 boundary scan with flying probe target vectors maximizes fault coverage on high-density PCBs while slashing test times and fixture costs.
Solder Bridges
Defect Condition
Unintended conductive connection formed between adjacent solder joints creates short circuits on assembled printed circuit boards. Excess alloy deposition causes solder bridges during wave or reflow soldering processes, bridging fine-pitch component leads or surface-mount pads. Manufacturing standards classify short circuits caused by unwanted solder as major workmanship defects requiring rework.
Formation Mechanism
Molten solder surface tension fails to separate adjacent pads when stencil aperture volume exceeds solder mask clearance limits. Excess solder paste printing, misaligned stencil registration, and insufficient solder mask dam thickness promote solder bridges during reflow profile peak temperatures. Dragging actions during wave soldering also cause molten solder alloys to span across closely spaced pin header leads when conveyor speed or solder pot temperature deviates from validated parameters.
Component placement misalignments squeeze printed solder paste laterally, joining separate solder deposits prior to heating. PCB fabrication facilities specify minimal solder mask clearance dams between fine-pitch integrated circuit pads to contain molten alloy flow.
Inspection Method
Automated optical inspection systems flag abnormal solder shapes between adjacent lead terminations before electrical testing. X-ray inspection equipment identifies hidden solder bridges beneath ball grid array packages where visual access is impossible. Technicians repair identified short circuits using desoldering braid and targeted thermal flux application to meet acceptance standards.