Normalizing Throughput Yield

[Pages:16]Normalizing Throughput Yield

White Paper

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Normalizing Throughput Yield

"A Practical Guide for Yield Normalization"

A White Paper

by

David C. Wilson, MSEE

Wilson Consulting Services, LLC December 23, 2004

WP-1: DCW_Normalizing Throughput Yield 12-23-04

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Normalizing Throughput Yield

Abstract

ABSTRACT

This paper provides a practical exercise for yield normalization using real data from a production line. The name of the company has been removed from this report for proprietary reasons. The intended audience is manufacturing, quality, and test engineering interested in evaluating operation and throughput yields. This information is being provided as result of the author's observations and a review of production yield data.

Yield is a measure of quality of a product relative to the manufacturing line. It is the fraction of total elements processed, which result in a good product. Production processes in manufacturing industries require yield parameters for making decisions of the goodness of the product. Therefore, yield data parameters are good measures of product performance as it is being produced. Data from products in the field provide another important source of information, which describes or predict its performance over time. Field data can be used both with statistical methodologies, plus some of the unfamiliar distributions such as Weibull, lognormal, exponential, gamma models, etc. Nevertheless, all of these

models call for inferences that involve extrapolation.

Wilson Consulting Services, LLC

WP-1: DCW_Normalizing Throughput Yield 12-23-04

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Normalizing Throughput Yield

Table of Contents

Description

Page

1.0: Introduction _______________________________________4 - 16

2.0: Summary _________________________________________5 - 16

3.0: Cumulative & Operation Yield_________________________9 - 16

4.0: Normalized Yield___________________________________10-16

5.0: Yield Scorecard____________________________________14 -16

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Normalizing Throughput Yield

Introduction

1.0 Introduction

Objective: ? To measure throughput yield in production with a comparative analysis of the

cumulative versus the normalized methods.

Data Source: ? Examples were taken from April 2003 Monthly Quality Yield Report.

Software Tools ? Excel ? Minitab

Definition of Yield: ? Yield is a measure of quality of a product relative to the manufacturing line.

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Normalizing Throughput Yield Introduction ? cont'd

Definition of Terms used

Y e ? Throughput yield : = -DPU TP

? Defects per unit : DPU = - ln(Y )

m

Y Y ? Rolled throughput or cum yield : =

RTY

TPi

i =1

( ) Y ? Total Defect per Unit : TDPU = - ln RTY

Y Y Y ? Normalized yield :

=m

or m

norm

RTY

cum

(Y ) ? Defect per normalized unit : DPU norm = - ln norm

?FPY n : for period yield n

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Normalizing Throughput Yield

Summary

2.0 Summary

The difference between the two methods is statistically significant with p-value = 0.001 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

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