Placement Rate Brochures against the Line That Runs the Job
Nominal SMT placement rates ignore vision latency, board transport dead time, and nozzle swaps; real line throughput requires simulation-derived cycle times.
Coplanarity Inspection
Lead Measurement
Lead height verification gauges the vertical deviation of surface mount device termination feet relative to a common seating plane before board attachment. Coplanarity inspection prevents open circuits on printed circuit boards by identifying deformed leads that fail to touch solder paste during reflow. Optical or laser sensors capture the spatial coordinates of every pin tip simultaneously, comparing individual heights against an absolute zero plane established by three primary contact points.
Component leads exceeding predefined height tolerances generate rejection flags before placement machines drop defective parts onto solder pads.
Solder Joint
Solder bridging occurs when excessive paste volume combines with poor lead deformation control, creating unintentional electrical shorts between adjacent pins during thermal processing. Insufficient paste transfer happens when an elevated lead floats above the deposit, leaving zero meniscus formation after the board exits the convection oven. Thermal expansion mismatches between the silicon package and the laminate substrate place mechanical stress on marginal joints, turning initial microcracks into complete opens over operational thermal cycles.
Process Limit
Maximum allowable vertical displacement depends strictly on pitch dimensions, where finer lead spacing demands tighter tolerances to prevent adjacent bridging and non-wetting defects. Automated optical metrology systems apply triangular laser triangulation to measure height variations down to micrometre resolution without exerting physical pressure on fragile gull-wing leads. Production floors set reject thresholds at fifty percent of the nominal paste thickness deposited by the stencil printer, ensuring every terminal establishes reliable contact during reflow.