# Wafer Cost Per Good Die Calculator

> Source: https://netray.co/tools/wafer-cost-per-good-die-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Convert wafer price, die size and yield into cost per good die and cost per packaged unit.

## Category

cost-finance

## Industry

Semiconductors

## Audience

- Product engineer
- Fab finance
- Procurement
- OSAT planner

## Tool

**Kind:** calculator

**Currency:** $

**Inputs:**

#### Wafer cost

**Key:** wafer_cost

**Type:** number

**Default:** 4500

**Min:** 0

**Step:** 100

**Unit:** per wafer

**Help:** Processed wafer price or fab standard cost.

#### Wafer diameter

**Key:** wafer_d

**Type:** select

**Default:** 300

**Options:**

##### 150 mm

**Value:** 150

##### 200 mm

**Value:** 200

##### 300 mm

**Value:** 300

#### Die width

**Key:** die_w

**Type:** number

**Default:** 8

**Min:** 0.5

**Step:** 0.1

**Unit:** mm

#### Die height

**Key:** die_h

**Type:** number

**Default:** 8

**Min:** 0.5

**Step:** 0.1

**Unit:** mm

#### Scribe lane

**Key:** scribe

**Type:** number

**Default:** 0.1

**Min:** 0

**Step:** 0.01

**Unit:** mm

#### Edge exclusion

**Key:** edge

**Type:** number

**Default:** 3

**Min:** 0

**Step:** 0.5

**Unit:** mm

#### Defect density D0

**Key:** d0

**Type:** number

**Default:** 0.2

**Min:** 0

**Step:** 0.01

**Unit:** defects/cm2

#### Wafer sort cost

**Key:** sort_cost

**Type:** number

**Default:** 120

**Min:** 0

**Step:** 5

**Unit:** per wafer

#### Assembly and package cost

**Key:** assy_cost

**Type:** number

**Default:** 0.85

**Min:** 0

**Step:** 0.05

**Unit:** per unit

#### Assembly and final test yield

**Key:** final_yield

**Type:** number

**Default:** 97

**Min:** 1

**Max:** 100

**Step:** 0.5

**Unit:** %

**Outputs:**

#### Die pitch area (mm2)

**Key:** pitch

**Expr:** (die_w + scribe) * (die_h + scribe)

**Format:** decimal

#### Usable diameter

**Key:** ud

**Expr:** wafer_d - 2 * edge

**Format:** decimal

#### Gross die per wafer

**Key:** dpw

**Expr:** floor(pi * pow(ud / 2, 2) / pitch - pi * ud / sqrt(2 * pitch))

**Format:** integer

#### Defects per die

**Key:** lam

**Expr:** die_w * die_h / 100 * d0

**Format:** decimal

#### Die yield (Murphy)

**Key:** yield_pct

**Expr:** if(gt(lam, 0.000001), pow((1 - exp(-lam)) / lam, 2), 1) * 100

**Format:** percent

#### Good die per wafer

**Key:** good

**Expr:** dpw * yield_pct / 100

**Format:** decimal

#### Cost per good die

**Key:** cost_good

**Expr:** (wafer_cost + sort_cost) / good

**Format:** currency

**Primary:** true

**Description:** Wafer plus sort cost divided by good die.

#### Cost per packaged unit

**Key:** cost_unit

**Expr:** (cost_good + assy_cost) / (final_yield / 100)

**Format:** currency

**Primary:** true

**Description:** Adds assembly cost and spreads assembly and final test loss over good units.

**Chart:**

#### Cost per good die vs defect density D0

**Type:** line

**X:** d0

**From:** 0.05

**To:** 1.5

**Steps:** 30

**Series:**

- cost_good
- cost_unit

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

## Content

**Intro:** 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.

**Sections:**

#### How to use it

**Body:** 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

**Body:** 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.

**Bullets:**

- 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

**Body:** 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.

**Cta:** 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.

**Faq:**

#### What is included in cost per good die?

**Answer:** 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?

**Answer:** 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?

**Answer:** 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?

**Answer:** 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.

## Search terms

wafer cost per die calculator, cost per good die, semiconductor cost model, die cost calculator, wafer price per die, chip cost calculator, known good die cost, packaged unit cost

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