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Holistic Reliability The Modern Day Solution to achieving World Class

Reliability

Martin Shaw – Reliability Solutions www.reliabilitysolutions.co.uk

Copyright © 2016 reliability solutions all rights reserved


Reliability Solutions – Background


Abbreviations

• DQA – Design Quality Assurance

• DFM – Design for Manufacture

• DFA – Design for Assembly

• DFT – Design for Test

• ELP – Early Life performance

• ALT – Accelerated Life Test

• M.P – Mass Production

• NPI – New Product Introduction


Background

• In today’s business you simply CANNOT separate Reliability from all other areas of product and process development

• Reliability Engineers can no longer rely on old standards such as Mil-Std 217 or using software packages only to estimate possible future failure levels

• Using old fashioned standard High Temp Accelerated Life Testing (ALT) simply does not stimulate the types of complex weaknesses found in modern product designs with wireless connection, battery support, multi processors, etc

• As consumer electronic products have become more complex and are regarded as throw away type items, the need to understand and measure reliability has become CRITICAL to SUCCESS and PROFIT

• A new approach is ESSENTIAL


Introduction

• Form 30 yrs experience in working with numerous clients, Reliability Solutions have developed the most effective ‘Holistic’ approach to achieving WORLD CLASS Reliability

• Holistic ‘is a belief that the parts of something are intimately interconnected and explicable only by reference to the whole’

• 6 key improvement Focus Items are used which bring highest level of return in defect reduction;

1) % Design Maturity Measure based on success of Design Quality Testing

2) DFA / DFT % score based on detailed methodology and scoring

3) Early Life Reliability Test data from unique Early Life Test approach per product type

4) Process Early Life Failure escape prediction from process failure / yield data

5) ALT output / fail rate prediction

6) DFMEA summary scoring with overall scoring based on potential defect grading

• Working in a systematic manner with simultaneous focus on all 6 areas will MAXIMISE production yield, efficiency AND Reliability

• In today’s business you simply CANNOT separate Reliability from all other areas of product and process development


How is it Done ?

• Basically it is ALL ABOUT MEASUREMENT and ensuring a clear OBJECTIVE approach to

improvement. As we all know, ‘You cannot improve what you cannot measure’

– Apply STRONG test programmes with MEASUREMENTS which can be used to asses future product

reliability

• Set up key measurements which all contribute to future product failure levels , though none individually may correlate directly

1) % Design Maturity Measure based on success of Design Quality Testing

2) DFA / DFT % score based on detailed methodology and scoring

3) Early Life Reliability Test data from unique Early Life Test approach per product type

4) Process Early Life Failure escape prediction from process failure / yield data

5) ALT output / fail rate prediction

6) DFMEA summary scoring with overall scoring based on potential defect grading

• Develop the overall model that takes all measurements and combine in a suitable statistical manner to provide a single output score

The Holistic Approach


How is it Done ?

1. % Design Maturity Score

• Establish Design Quality Test Matrix with

range of function stress tests and ELP, ALT

• Each Test given weighted score based on

ability to stimulate latent defects

• Failures are scored based on severity and

resolution status

• Overall test Score is cumulative of all

individual test scores

• DQA % Maturity is ratio of (Total Points

achievable – defect scores / Total Points)

• Provides a STRONG measure of Design

Quality

• Design Maturity Example – 81%


How is it Done ?

Test Item Test Weight Score EVT

Visual check Minor 30 PASS

Performance test Critical 100 PASS

Operating Rated voltage test Major 70 PASS

Output Voltage Critical 100 PASS

Operating Angle Critical 100 PASS

Supply Reverse @5V DC Minor 30 PASS

Output Shor circuit @ 5V DC Minor 30 PASS

Installation coverage angle Major 70 PASS

Storage at Low temperature Major 70 PASS

Storage at high temperature Major 70 PASS

Operating at High temperature Major 70 PASS

Temperature cycling tests Major 70 PASS

Thermal Shock Major 70 PASS

Temperature and Humidity Cycle Major 70 PASS

Resistance to Water - IP65 Major 70 PASS

Salt spray Minor 30 PASS

Vibrations Major 70 Fail-2017

Drop test Major 70 Fail-2017

Dust proofness Minor 30 PASS

Oil resistance test Major 70 PASS

Gasoline resistance test Major 70 Fail-2017

Endurance test 1 Critical 100 PASS

Endurance test 2 Critical 100 PASS

Terminal section stregth Minor 30 PASS

Lead wire tensile test Major 70 PASS

UV resistant testing (Xenon Arc) Major 70 PASS

Electrical stress test - Transient voltage 3A 3B Critical 100 Fail-2017

Electrostatic discharge Critical 100 Fail-2017

Electromagnetic interferance test-BCI: 11452-4 Critical 100 PASS

Rediated Immunity Critical 100 PASS

Rediated Emission:CISPER-25 Critical 100 PASS

Conducted Emission:CISPER25 Critical 100 PASS

Resistance to Water - IP67 Critical 100 PASS

PCBA, Pendulum Accel Stress Test Critical 100 PASS

Full Product Accel Life Test Critical 100 PASS

5

235

2630

91.06%

New Fail Item

Points Lost to Date

Max Score

Design Maturity


How is it Done ?

Total Max Score

Total

Actual

Score

% of EVT

Readines

s

3060 2660 86.93%

Formula = Total Actual Score / Total Max Score

Priority 1 = 5 Points (High impact)

Priority 2 = 3 Points (Mid impact)

Priority 3 = 1 Point (Low impact)

Item Description Status Priority Max Score Actual

1 Availability? Completed 2 3 3

2 Compatible with manufacturing process? Completed 2 3 3

3 Source reliability Completed 1 5 3

4 Price variability? Completed 1 5 5

5 Optimization? Completed 1 5 3

6 CTFs: what are the failure limits Completed 2 3 3

7 CTFs: what are the process capability limits? In Progress 1 5 3

8 CTFs: what is the margin or factor of safety? In Progress 2 3 2

9 Is the metrology plan clearly described? In Progress 1 5 3

10 Material economy? Completed 2 3 3

11 Verify plastic design rules. Completed 2 3 3

12 Tooling review. Completed 2 3 3

13 Production Part Approval Process (PPAP) Open 2 3 0

14 Appropriate tool? Completed 2 3 3

15 Verify sheet metal design rules. Completed 2 3 3

16 Tooling review. In Progress 2 3 2

17 Production Part Approval Process (PPAP) Open 2 3 0

18 Appropriate tool? Completed 2 3 3

19 Verify design rules. Completed 2 3 3

20 Tooling review. Completed 2 3 3

20 Production Part Approval Process (PPAP) Completed 2 3 3

Mechanical Design: Sheet Metal Parts

Mechanical Design: Other Processes

Mechanical Design: Plastic Parts

Design for Assembly - EVT

Material

Fabricated Parts

• Products not designed for efficient high

quality assembly suffer too many in-

process reworks

• Results in escapes of latent defects to the

field not caught in normal func testing, Early

Life failure rate is affected

• Poor Design for Test results in poor test

coverage, too many escapes

• Need organized DFM / DFT assessments

with scoring for benchmarking and continual

improvement measure

• Example, DFA Score 86.9%

2. DFA Scores


How is it Done ?

3. Early Life Reliability Testing

• Sequential short duration stress testing required, Use mix of different stress methods to

achieve high Test Strength

• High Volume samples, units can be shipped without concern after test unlike ALT

• High level of defect detection with poor designs

– PCBA component / process fails

– Bad Assy defects

– Unseated connectors

– Etc

• Score achieved based on

No. defects

0 def – 100%

<3 def – 50%

> 2 def - 0


How is it Done ?

4. Predicting Early Life Failure escapes from Process data

• Applying the appropriate model and correlating with Field Data shows how Process Yield data can be used to predict Field Fail Levels from M.P

Developed for Electronic Sub-Systems in LCD TV, equally appropriate to other products

Example of approach taken to show Power Board Prediction from Process data

Develop correlation model to take Rolled yield and predict Early Life Failure rate, example


How is it Done ?

5. ALT Fail Prediction

• ALT cannot be standard test, must characterize product to MAXIMISE stress level below Design

Limit, create UNIQUE profiles to each product

• Combine range of stress methods; Temp/Humidity, Power Cycling, Voltage change, etc

• Develop a profile that gets repeated continuously to detect issues within design limits

• Power gets applied at range of temps and voltage levels, power cycling excites defects


How is it Done ?

6. DFMEA Summary Scoring

• DFMEA is important but needs to be TAILORED for a Non Standard approach

• Simply using RPN scores does NOT give overall rating of Design Capability

• Use simple approach to score DFMEA output and use in Holistic scoring

• In this example, the product receives a ‘0’ score

RPN Score Groupings 0-199 200 - 399 400 - 599 600 - 699 700 - 799 800 - 899 900 - 999 Score Rules

Total Grouping Scores 151 81 18 7 4 4 1 > 2500 0

Score Scaling 2 8 32 128 128 128 128 2001-2500 0.25

Adjusted Group Scoring 302 648 576 896 512 512 128 1501-2000 0.5

1001-1500 0.75

Tot RPN Rating Score 3574 < 1000 100%


Holistic Reliability and the NPI Model

• Relying on personal views from engineers or managers is VERY RISKY !! ,An organised measurement approach is the answer with a scoring model to provide strength in decision making

• The Holistic solution now needs a summary of all the measurements / scores into a single SIMPLE

Table, the New Product Introduction (NPI) Summary;

Product Realization 30 82 24.6


Product Realization 20 50 10

M.P Trial 15 60 9


Process Realization 10 0 0

TOTAL SCORE 100 66.65

Ratio 67%

TARGET 85

NPI SCORING MODEL

2. DFA

1. DesignMaturity

6. DFMEA Score

3. Product ELR Rel Test (Early life Reliability)

5. ALR long term reliability test (Accelerated Life Reliability)

Key Measures / Review PointsActual

Score

% Score /

WeightingMax Score

4. Process Yield Measurement

NPI Scoring

Seminar Models/Holistic NPI Scoring Template 201117.xls





Process Realization 3 92 2.76

0


M.P Trial 3 1 3




M.P Trial 8 100 8


M.P Trial 3 95 2.85


M.P Trial 5 80 4

M.P Trial 7 100 7

M.P Trial 5 0 0


M.P Trial 5 80 4

TOTAL SCORE 100 88.23

Ratio 88%

11. Process Yield Measurement

10. Mould Tooling Readiness Review

Note - Scores achieved from DFMA Report Score

Note - Scores achieved from DFT Report Score

Note - % Design Maturity from DQA Reporting

XXXX NEW PRODUCT SCORING MODEL

2. Product Lvl DFM/DFA

1. DFMEA

Note - Scores achieved from RPN summaries in DFMEA report

6. Technical Process Validation

Note - Scores achieved from RPN summaries in PFMEA report

Max Score% Score /

WeightingActual Score

4. PCBA DFSS (DESIGN FOR SIX SIGMA)

8. Product ELR Rel Test (Early life Reliability) ORT

7. Factory Process Readiness Review (QAV)

Key Measures / Review Points

5. Gross Design Maturity (DQ compliance testing / RD)

9. ALR long term reliability test (Accelerated Life Reliability)

3. PFMEA


Working with Reliability Solutions

• Martin Shaw performs GAP analysis at new Customers wishing to run an overall Improvement Programme

Each of Key Item areas are assessed plus additional areas he feels would feel need improvement

Detailed Executive Report is issued to define GAP analysis summary with list of Actions / Projects that will be required to make necessary improvements

Key Measurements defined that directly relate to each Project’s Success level

• Process Yields, DQA Maturity, Key Comp ppm , NPI, Field Return Rates, etc

• Project Teams are formed for each Key Improvement Project defined in GAP Analysis

Key individual at Client is nominated to handle Project Mgmt with Martin Shaw

• Project Schedules defined and Teams begin projects, Project Management handled by Martin Shaw and a nominated client representative for communication internally

• Outline of support required from Reliability Solutions is defined with Costs

Includes the on site reviews at client (recommended every 10-12 wks)

holistic reliability the modern day solution to achieving ... · process realization 5 90 4.5 m.p...

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