Calculations

How to Calculate SMT Throughput, Cycle Time, and PCB Panel Yield

A step by step walkthrough of the five formulas that govern SMT and PCB output, each solved with real component counts, panel dimensions, and CPH figures.

Everything on an SMT line traces back to placement rate. A machine rated at 40,000 components per hour (CPH) never hits nameplate, so use effective CPH. If a chipshooter is rated at 40,000 CPH but runs at 72 percent efficiency on a mixed board, effective rate is 40,000 times 0.72, or 28,800 CPH. For a board with 1,150 placements, placement time per board is 1,150 divided by 28,800 hours, which is 0.0399 hours, or 143.7 seconds. The SMT Placement Rate calculator does this conversion and lets you split fine-pitch, BGA, and odd-form parts that each carry different nozzle indexes and vision times.

Cycle time is the placement time plus the fixed non-placement overhead per board: board load, fiducial alignment, conveyor transfer, and reflow indexing. Take the 143.7 seconds of placement above and add 11 seconds of transfer and index overhead, and cycle time is 154.7 seconds per board on the constraining machine. The line beat rate is set by the slowest station, not the average. If your printer runs at 45 seconds and your slowest placement head runs at 154.7 seconds, the line moves at 154.7 seconds. The SMT Cycle Time calculator isolates the bottleneck station so you size to the real constraint.

Throughput converts cycle time into boards per shift after availability. Gross boards per hour equals 3,600 divided by cycle time in seconds. At 154.7 seconds that is 23.3 boards per hour. Apply line availability and first-pass yield: 23.3 times 0.85 uptime times 0.97 yield gives 19.2 good boards per hour, or 153 good boards across an 8-hour shift. The SMT Line Throughput calculator strings these together so you can see gross capacity, uptime loss, and yield loss as separate board counts rather than one blended number that hides where output leaks.

Utilization tells you how hard the placement asset actually works. Pick-and-place utilization equals productive placement time divided by scheduled time. If a machine places for 5.4 hours of an 8-hour scheduled shift, utilization is 5.4 divided by 8, or 67.5 percent. The other 2.6 hours went to changeovers, feeder reloads, and starvation waiting on the printer. The Pick-and-Place Utilization calculator separates these buckets. On high-mix lines, feeder work dominates, which is why the Feeder Setup Time calculator matters: 60 feeders at 90 seconds each is 90 minutes of setup, and that setup falls on every job changeover, not once.

Panel math sets your material base. Boards per panel depends on the usable panel area after rails and the board footprint plus routing gap. A 457 by 610 mm panel with 12 mm rails yields roughly 433 by 586 mm usable. A 60 by 40 mm board with a 3 mm gap occupies 63 by 43 mm, so you fit 6 columns by 13 rows, or 78 images, before scrap features. The Boards Per Panel calculator handles orientation flips and step-and-repeat, and PCB Panel Utilization reports the area ratio: 78 boards times 2,400 mm squared each is 187,200 mm squared of 278,338 mm squared usable, a 67 percent utilization.

Solder paste usage ties the stencil to consumption and cost. Volume per board equals the sum of aperture areas times stencil thickness times a transfer efficiency near 0.9. For a board with 6,200 mm squared of total pad area under a 0.12 mm stencil, deposited paste is 6,200 times 0.12 times 0.9, or 669 mm cubed per board. At a paste density of 4.5 grams per cubic centimeter, that is 3.0 grams per board. The Solder Paste Usage calculator converts this to jars per 1,000 boards and flags stencil-life waste, since paste left on the stencil at end of shift is unrecoverable.

Put the chain together with real inputs and the numbers reconcile. Take 153 good boards per shift at 3.0 grams of paste each: that is 459 grams of deposited paste per shift, plus stencil and squeegee losses that typically add 15 to 25 percent, so budget roughly 550 grams. Across 78-up panels, 153 boards is only 2 complete panels of demand per shift on that product, which tells you the panel utilization decision and the placement bottleneck are the two levers that move output. Every downstream cost estimate depends on getting these five numbers right first.

A common trap is mixing per-board and per-panel units mid-calculation. If your placement count is per image but your cycle time is measured per panel of 78 images, throughput is off by 78 times. Always state the unit basis before you compute: components per image, images per panel, panels per hour. When you feed the SMT Line Throughput and Boards Per Panel calculators, confirm both use the same basis. A single unit mismatch here is the difference between quoting 150 boards a shift and quoting 11,700, and that error survives all the way to the customer quote.

Published 2026-07-01.