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Wafer Cost Per Good Die Calculator

The wafer price is only the start of a die cost. This calculator walks from wafer cost through gross die, a yield model, wafer sort and assembly to the cost of a packaged unit that works.

Your numbers

per wafer

Processed wafer price or fab standard cost.

mm
mm
mm
mm
defects/cm2
per wafer
per unit
%

Your results

Cost per good die
$5
Wafer plus sort cost divided by good die.
Cost per packaged unit
$7
Adds assembly cost and spreads assembly and final test loss over good units.
Die pitch area (mm2)
65.61
Usable diameter
294
Gross die per wafer
954
Defects per die
0.128
Die yield (Murphy)
88.1%
Good die per wafer
840.5268

A planning model only. Real costs include mask amortization, yield learning, test time, burn in, known good die handling and overhead.

Save results:

Cost per good die vs defect density D0

Sweeps Defect density D0 from 0.05 to 1.5, holding your other inputs fixed.

Model versus ERP actuals

Want modeled die cost compared with real standard and actual costs from your ERP? Ask for an optional expert review.

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

How to use it

Enter the wafer price, wafer diameter, die dimensions and the layout assumptions for scribe lane and edge exclusion. Enter D0 for the process and the wafer sort cost per wafer. Add assembly cost per unit and the combined assembly and final test yield. The calculator computes gross die, Murphy yield, good die per wafer, cost per good die and cost per packaged unit. The chart shows how both costs climb as D0 rises, which is the quickest way to see what a yield problem is worth.

The cost chain

Cost per good die is (wafer cost + sort cost) divided by good die per wafer. Good die equals gross die times yield. Packaged cost then adds assembly and divides by the assembly and final test yield, since units lost late in the flow carry the whole cost already spent on them. The result is intentionally simple. It does not include design amortization, mask sets, probe card wear, yield learning or inventory carrying cost.

  • Gross die from the analytic die per wafer formula
  • Murphy yield from die area and D0
  • Sort cost added before dividing, because bad die are still probed
  • Assembly yield applied to the packaged result

Reading results and ERP notes

With the defaults you should see a cost per good die in the low single digits of dollars, and a packaged cost slightly above it. A 20 percent change in D0 matters little for a small die and a lot for a big die, so use the chart on your actual die. In ERP, the same chain shows up as wafer standard cost, a yield or scrap factor on the BOM or routing, and a test and assembly operation cost. Check your standard costs reflect actual yield, otherwise inventory variances will hide the problem.

Frequently Asked Questions

What is included in cost per good die?

Wafer price and wafer sort cost divided by good die per wafer. It leaves out assembly, final test, design amortization and overhead, which the packaged unit output partly adds.

Which yield model does it use?

It uses the Murphy model from die area and D0. For other models use the die yield calculator and enter the yield into your own spreadsheet. The choice shifts results most for large die.

Why include sort cost before dividing?

Every die is probed whether it passes or not, so the cost of probing bad die is carried by the good ones. Dividing wafer plus sort cost by good die captures that.

Can I use it for foundry quotes?

Yes as a cross check. Compare the quoted wafer price with your die size and expected D0 to see if the cost per good die fits your target. Final quotes include minimums, masks and terms.

Netray can compare modeled cost per die with actual costs and yields from your ERP, so finance and process engineering work from the same numbers on private infrastructure.

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