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Wafer Probe Throughput and Test Cell Capacity Calculator

This calculator estimates how many wafers a wafer probe cell can test per hour and per week, based on dies per wafer, parallel sites, test time, prober index time, load overhead and retest rate. It is built for test engineers and capacity planners who need a quick answer before spending on probe cards or testers.

Your numbers

Dies per wafer

dies

Gross die tested per wafer.

Parallel test sites

4 sites

Dies probed in each touchdown.

Test time per touchdown

Prober index time

Move time between touchdowns.

Wafer load and align overhead

Retest rate

Share of touchdowns repeated.

Prober and tester cells

cells

Calendar hours per week

Cell utilization

Share of time spent testing after downtime, setup and idle.

Your results

Wafers per hour per cell

5.8824

Wafers per week, all cells

2,224

Touchdowns per wafer

300

Seconds per wafer

612

Dies tested per hour per cell

7,059

Simplified model. Real throughput also depends on probe card cleaning, edge die partial touchdowns, wafer map handling, temperature soak and prober specific timing. Measure on the real cell to calibrate.

Save results:

Wafers per hour vs parallel sites

Sweeps Parallel test sites from 1 to 32, holding your other inputs fixed.

Capacity planning from live ERP data

Optional: see how test cell capacity can be compared with open work orders in your ERP.

Optional. The tool and every export work without this. No spam.

How to use it

Enter the die count per wafer and the number of parallel sites your probe card supports. Add the test time per touchdown, the prober index time and the wafer load overhead, then set a retest rate and utilization. The result is wafers per hour per cell and total weekly capacity across all cells. The chart shows how adding sites changes throughput.

Use measured test time from the real test program
Keep utilization realistic after downtime and setup
Compare multi-site options on the chart

The formula

Touchdowns per wafer is dies divided by sites, rounded up. Time per wafer is touchdowns times one plus the retest fraction, times the sum of test time and index time, plus the wafer load overhead. Wafers per hour is 3600 divided by that time. Weekly capacity multiplies by the hours, utilization and number of cells.

Worked example

With 1,200 dies, 4 sites, 1.5 s test time and 300 ms index, there are 300 touchdowns. With a 5 percent retest rate, the touch time is 300 times 1.05 times 1.8 s, or 567 s, plus 45 s load for 612 s per wafer. That is about 5.9 wafers per hour per cell, and roughly 2,200 wafers per week for three cells at 75 percent utilization.

Common mistakes

Assuming perfect multi-site efficiency overstates throughput, because edge dies and partial touchdowns waste sites, and parallel test time can grow with site count. Another mistake is using calendar capacity as if utilization were 100 percent. Finally, do not forget extra time for temperature tests, where thermal soak can dominate.

Frequently Asked Questions

What is a touchdown in wafer probing?

A touchdown is one contact of the probe card with the wafer. With multi-site probing, one touchdown tests several dies in parallel, so fewer touchdowns are needed per wafer.

Why is edge die handling not modeled?

Edge dies create partial touchdowns where not all sites are used. This tool uses a simple ceiling of dies divided by sites. For precise numbers, use the prober's actual touchdown map.

How do I reduce wafer probe cost per die?

Increase parallel sites, shorten test time through test program optimization, reduce retests and improve utilization. Each affects the time per wafer shown in this model.

Does test time grow with more sites?

Often yes, a little, because tester resources are shared and some tests are serialized. Use a measured test time at the target site count rather than the single site time.

If you want capacity and WIP questions answered from your ERP and test data in plain language, Netray can set that up on-prem.

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