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The Economics of Test

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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The Economics of Test

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  1. The Economics of Test Tony Ambler Dept. of Electrical and Computer Engineering The University of Texas at Austin ambler@ece.utexas.edu

  2. From PRODUCTION through to PRODUCT RETIREMENT

  3. COSTS OF DESIGN FOR TEST BIST Scan No DFT Total Manufacturing Costs Number of ICs Produced

  4. COSTS OF DESIGN FOR TEST No DFT Cost With DFT Production Volume

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Pre-Conceived Ideas Are As Old As... Stonehenge

  11. Preconceived Ideas like…. “He won’t get there any quicker…”

  12. Pre-Conceived Ideas Like…….. “But…… We’ve Always Done It This Way!”

  13. Pre-Conceived Ideas Like…….. “Everyone Knows That This Is The Expensive Part Of the Operation...”

  14. Pre-Conceived Ideas Like…….. “It’s Someone Else's Problem”

  15. Pre-Conceived Ideas Like…….. Our Quality is Great!

  16. Pre-Conceived Ideas Like…….. “To Get Better Quality, Means We Have to Test More, Which Will Cost Us More Money”

  17. Pre-Conceived Ideas Like…….. “Just Add Scan Path And It Should Be Alright”

  18. 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

  19. 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

  20. 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

  21. 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

  22. COST OF DFT Scan BIST Silicon area (Fault Coverage) TPG Fault Simulation ATE Package (pins) ~

  23. 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…

  24. COSTis a common reference point RELATIVE IMPORTANCE determined in financial terms

  25. ‘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.

  26. 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

  27. Effect of Changing Purchasing/Contract Policy On Total Life Cycle Cost of Ownership CONSEQUENTIAL LOSS

  28. 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…

  29. PERIPHERAL ISSUES • Time to Market • Company Policy • Company Image • Warranty • Product Liability • Safety-Critical Systems • Performance

  30. 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)

  31. 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…

  32. 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

  33. 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

  34. Test Economics in a Nutshell: IT DEPENDS...

  35. Test Economics in a Nutshell: IT DEPENDS... But it sure does matter a lot… …and be careful how you use/apply the data…

  36. Y’All

  37. 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...

  38. They Hear That Money Is Involved! So... Are Design selection CAD tools like marriage bureaux?

  39. “Price is not the only cost” The Best of DEMING collected by Ron McCoy SPC Press

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