The Economics of Test. Tony Ambler Dept. of Electrical and Computer Engineering The University of Texas at Austin firstname.lastname@example.org. From PRODUCTION through to PRODUCT RETIREMENT. COSTS OF DESIGN FOR TEST. BIST. Scan. No DFT. Total Manufacturing Costs. Number of ICs Produced.
Economics of Test
Dept. of Electrical and Computer Engineering
The University of Texas at Austin
Total Manufacturing Costs
Number of ICs Produced
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
number of boards
COMPARISON OF COSTS FOR DIFFERENT BOARD TEST METHODS -5,000 SYSTEMS
Total Production & Test Cost
COMPARISON OF COSTS FOR DIFFERENT BOARD TEST METHODS -50,000 SYSTEMS
Total Production & Test Cost
add ‘treuer’ to node 1
int_scan, node 3
ext_scan, node 2
int_scan, node 2
‘March’, node 4
“He won’t get there any quicker…”
We’ve Always Done It This Way!”
“Everyone Knows That This Is The
Expensive Part Of the Operation...”
“It’s Someone Else's Problem”
Our Quality is Great!
“To Get Better Quality,
Means We Have to Test More,
Which Will Cost Us More Money”
“Just Add Scan Path
And It Should Be Alright”
Method of Cost Accounting
Mean Time to Diagnosis
Field Spare Inventory
Product Distribution Cost
Test & Support
Design and Test:
DFT and test time
DFT and ATE:
Depreciation and maintenance
Operator & Programming Cost
Test Program Length
Program Fault Cover
Program Preparation Time
Test and Diagnosis Time
Number of Board Types
Cost of Field Service:
Repair Depot Cost
Field Repair Cost
Curtailing Repeat Visits
Design for Maintainability
Design cycle time
Fewer design changes
Lower ATE cost
EFFECT OF DFT COST BY DEPARTMENT
determined in financial terms
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.
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
- Reliability degradation
20% of Service Calls are Repeat Visits
Down Time Costs…Penalty Clauses…Repeat Sales
Total Life Cycle Cost of Ownership
Removing the problem of incorrect documentation reduces the cost of ensuring all documentation is up-to-date.
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)
Instrumentalities That Affect the Quality of Products
Primary influencers of new, cost effective and safe products:
1. Engineer/designer (service)
2. Manufacturer (product)
Causes of (responsibility for) product failure:
1. Defective design
Floppy Disc Controller…
Test Costs in Design is one of several issues
Time to Market
…depending upon product type/area/application/
volume/complexity/marketplace…but the numbers can still be large $$$$$$$$$$$$$$$$$$$$$
Adding in LIFECYCLE implications makes a BIG difference
Value-Focused Thinking: A Path to Creative Decision Making, Ralph Keeney, Harvard Press, 1992
But it sure does matter a lot…
…and be careful how you use/apply the data…
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
Are Design selection CAD tools
like marriage bureaux?
The Best of DEMING
collected by Ron McCoy