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The Economics of Test. Tony Ambler Dept. of Electrical and Computer Engineering The University of Texas at Austin ambler@ece.utexas.edu. From PRODUCTION through to PRODUCT RETIREMENT. COSTS OF DESIGN FOR TEST. BIST. Scan. No DFT. Total Manufacturing Costs. Number of ICs Produced.

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Presentation Transcript
slide1

The

Economics of Test

Tony Ambler

Dept. of Electrical and Computer Engineering

The University of Texas at Austin

ambler@ece.utexas.edu

slide2

From PRODUCTION through to

PRODUCT RETIREMENT

slide3

COSTS OF DESIGN FOR TEST

BIST

Scan

No DFT

Total Manufacturing Costs

Number of ICs Produced

slide4

COSTS OF DESIGN FOR TEST

No DFT

Cost

With DFT

Production Volume

slide5

BOUNDARY SCAN

Practical Applications of Boundary Scan

Production of PCB’s...

Boundary scan designed into the ASIC’s used in generation of test programmes, test diagnose times, repairs to defective PCB’s, tester investment...

Two board types, one with 100% boundary scan, the other with 0%!

YEARLY COST TOTAL REDUCED FROM $2,555K TO $1,325K

(based upon an analysis by Philips Electronics)

‘Boundary-Scan Test: A Practical Approach’, Bleeker et al, Kluwer 1993

cost per board vs production volume
COST PER BOARD VS PRODUCTION VOLUME

12,000

10,000

8,000

without b/s

6,000

cost per board

with b/s

4,000

2,000

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

11000

10000

number of boards

slide7

Field

System

Board

Design &

Production

COMPARISON OF COSTS FOR DIFFERENT BOARD TEST METHODS -5,000 SYSTEMS

Component

Test

Total Production & Test Cost

Wafer

Test

Packaging

no DFT

Scan

Bscan

slide8

Field

System

Board

Design &

Production

COMPARISON OF COSTS FOR DIFFERENT BOARD TEST METHODS -50,000 SYSTEMS

Component

Test

Total Production & Test Cost

Wafer

Test

Packaging

no DFT

Scan

Bscan

slide10

TEST STRATEGY PLANNING

(250,000 ICs)

18,000

17,000

Cost ($K)

16,000

15,000

14,000

1

2

3

4

5

add ‘treuer’ to node 1

int_scan, node 3

ext_scan, node 2

int_scan, node 2

‘March’, node 4

slide12

Preconceived Ideas like….

“He won’t get there any quicker…”

slide13

Pre-Conceived Ideas Like……..

“But……

We’ve Always Done It This Way!”

slide14

Pre-Conceived Ideas Like……..

“Everyone Knows That This Is The

Expensive Part Of the Operation...”

slide15

Pre-Conceived Ideas Like……..

“It’s Someone Else's Problem”

slide17

Pre-Conceived Ideas Like……..

“To Get Better Quality,

Means We Have to Test More,

Which Will Cost Us More Money”

slide18

Pre-Conceived Ideas Like……..

“Just Add Scan Path

And It Should Be Alright”

slide19

OPTIMUM DECISION-MAKING DEPARTMENTS

Accounting Practices

Method of Cost Accounting

Investment Plans

Strategic Direction

Management

Finance

Corporate Cost

Capital Utilisation

Optimum

Solution

Field Service

Design

Mean Time to Diagnosis

Field Spare Inventory

Design Time

Performance

Manufacturing

Test

Marketing

Test Yield

Manufacturing Cost

New Features

slide20

TOTAL COST VISIBILITY

Poor

Management

Acquisition Cost

(Junk)

Operations

Cost

Product Distribution Cost

Software

Cost

Test & Support

Equipment Cost

Maintenance

Cost

Technical

Data

Cost

Supply

Support

Cost

Training Cost

Retirement &

Disposal Cost

slide21

Test Economics

Design and Test:

Design costs

DFT and test time

Budget

Market forces

Quality/Reliability

Target throughput

Training

Packaging technology

Circuit layout

Silicon cost

Pin out

Cad tools

Designer’s skills

Performance degradation

Computing equipment

Capital investment

Test

Strategy

slide22

Test Economics

DFT and ATE:

Purchase cost

Depreciation and maintenance

Operator & Programming Cost

Setup Time

Test Program Length

Pin Memory

Labour Rates

Program Fault Cover

Program Preparation Time

Test and Diagnosis Time

Fixture Cost

Manufacturing Yield

Production Volume

Number of Board Types

Cost of Field Service:

Repair Depot Cost

Logistic Support

Field Repair Cost

Downtime Cost

Curtailing Repeat Visits

Design for Maintainability

Test

Strategy

slide23

COST OF DFT

Scan

BIST

Silicon area

(Fault Coverage)

TPG

Fault Simulation

ATE

Package (pins)

~

slide24

Die area

Design cycle time

Performance impact

EDA tools

Fault simulation

Simplified debug/diagnostics

Fewer design changes

Lower ATE cost

EFFECT OF DFT COST BY DEPARTMENT

DESIGN

TEST

Politics…

slide25

COSTis a common reference point

RELATIVE IMPORTANCE

determined in financial terms

slide26

‘OTHER’ TEST COST ANALYSES

A Company...

Sought to reduce test length by 50% - “insignificant”

Sought to reduce board/system test costs by ‘verifying’ the removal of a specified test stage.

Sought to verify their intended use of scan in all future chip designs. Analysis pointed the way to use of BIST

Analysed System Test – reduced factory system test costs and improved outgoing product quality.

slide27

LACK OF AUTOMATION

High Labour Costs

High Staff Training Costs

High dependency on human interaction causes inconsistency in service. Service prone to human error causing incorrect diagnosis.

- Increased service visits.

- Results in increased repair inventory and

transportation costs.

- Reliability degradation

20% of Service Calls are Repeat Visits

Down Time Costs…Penalty Clauses…Repeat Sales

slide28

Effect of Changing Purchasing/Contract Policy

On

Total Life Cycle Cost of Ownership

CONSEQUENTIAL LOSS

slide29

The Wider (Greater?) Issue

  • COTS test systems will be cheaper than the current tailor-made systems.
  • Training costs will be greatly reduced
  • Manpower requirements will be greatly reduced
  • Human factors-related errors will be reduced
  • Rehost time will be greatly reduced
  • Spares costs for ATE systems will be greatly reduced
  • Reliability of test systems will be improved
  • Up-time of weapons systems will be improved
  • Reliability of weapon systems is likely to be improved
  • Spares costs for weapon systems can be reduced
  • Transport costs of weapons system support will be greatly reduced

Politics…

slide30

PERIPHERAL ISSUES

  • Time to Market
  • Company Policy
  • Company Image
  • Warranty
  • Product Liability
  • Safety-Critical Systems
  • Performance
slide31

ON-LINE DOCUMENTATION

Removing the problem of incorrect documentation reduces the cost of ensuring all documentation is up-to-date.

Estimated

Savings

Fewer Repeat Calls 50%

Reduced Training 30%

Faster Repair Time 50%

Fewer On-Site Specialists 40%

Fewer Good Boards Swapped 40%

Reduced Pipeline Inventory 40%

Increased sales due to customer satisfaction ??%

Improve diagnostics due to increased quality of docs.

(Rosh Intelligent Systems)

slide32

PRODUCT LIABILITY ISSUES

Instrumentalities That Affect the Quality of Products

Primary influencers of new, cost effective and safe products:

1. Engineer/designer (service)

2. Manufacturer (product)

3. User

Causes of (responsibility for) product failure:

1. Defective design

Floppy Disc Controller…

slide33

Stuff…

Test Costs in Design is one of several issues

Time to Market

Physical Constraints

…depending upon product type/area/application/

volume/complexity/marketplace…but the numbers can still be large $$$$$$$$$$$$$$$$$$$$$

Adding in LIFECYCLE implications makes a BIG difference

slide34

VALUE-FOCUSED THINKING?

Creating

Alternatives

Uncovering

Hidden

Objectives

Identifying

Decision

Opport.

Guiding

Strategic

Thinking

Evaluating

Alternatives

Thinking

About

Values

Improving

Commun-

ication

Interconn-

ing

Decisions

Facilitating

Involvement in

Multiple-

Stakeholder

Decisions

Guiding

Information

Collection

Value-Focused Thinking: A Path to Creative Decision Making, Ralph Keeney, Harvard Press, 1992

slide36

Test Economics in a Nutshell:

IT DEPENDS...

But it sure does matter a lot…

…and be careful how you use/apply the data…

slide38

DESIGN SELECTION IS LIKE...

Choosing your spouse!*?

You each have your own specification for the ideal spouse

- Based upon some irrational criteria

- That can be altered by some fashion change

- Your parents/friends won’t agree on your choice

and then...

slide39

They Hear That Money Is Involved!

So...

Are Design selection CAD tools

like marriage bureaux?

slide40

“Price is not the only cost”

The Best of DEMING

collected by Ron McCoy

SPC Press