Selective Solder Process Windows for Plated through Hole Components
Selective solder process windows require matching top-side preheat above 110C with precise 3-second pin dwell times to achieve 75 percent Class 3 barrel fill.
Overall Cycle Time
Fabrication Duration
Surface mount technology production lines calculate overall cycle time by measuring the continuous interval from paste deposition through reflow soldering and final automated optical inspection. Board fabricators track this metric to expose material bottlenecks where pick and place machines starve or thermal profiles stall. Solder paste inspection feeds direct timing data into the software, establishing baseline parameters for every individual panel passing underneath the squeegee blades.
Conveyor speed adjustments and feeder replenishment delays dictate the practical limit of throughput efficiency. Operator intervention during component jam clearance adds variance to the baseline calculation, separating nominal machine speed from actual factory output.
Line Balance
Factory planners use overall cycle time to distribute placement work evenly across sequential modular heads, preventing starvation at high speed chip shooters. Feeder setups dictate whether placement heads complete their programmed arrays simultaneously or wait for slower dispensing modules to finish upstream. Thermal profiling constraints in convection ovens impose strict boundaries on belt velocity, forcing placement engineers to synchronize upstream feeder speeds with maximum solder reflow dwell limits.
Staggered component feeder allocation reduces idle time on cantilever placement gantries, converting erratic component distribution into smooth mechanical motion.
Yield Loss
Scrap rates distort overall cycle time calculations by consuming machine capacity on defective circuit boards that ultimately fail automated optical inspection or electrical test. Rework routing removes faulty assemblies from the main conveyor loop, introducing administrative delay and manual handling that inflates the rolling average duration per finished unit. Thermal shock during second pass reflow induces micro cracking in ceramic capacitors, triggering diagnostic pauses and scrap disposition routines that stall downstream packaging lines.
Component solder bridging forces immediate line stoppage for stencil wiping and squeegee pressure recalibration, degrading the metric through unscheduled downtime.