sk 09-sep-2002 motorola general use, kelly_quality_lhc motorola and the stylized m logo are...

SK 09-SEP-2002Motorola General Use, Kelly_Quality_LHC

MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2002.

Managing for Quality in the Electronics Industry

Sean Kelly

Motorola Inc.



Greetings Greetings from Arizonafrom Arizona

Motorola Computer GroupTempe, Arizona, USA

Saguaro Saguaro CactusCactus

Grand Grand Canyon Canyon



Introduction… What is Product Quality?

ProductQuality

Defect Rate

Reliability

Ease of UseServiceability

Look and Feel

Availability



Introduction… What is Product Quality?

ProductQuality

Defect Rate

Reliability

Ease of UseServiceability

Look and Feel

Availability

All of these attributes contribute to the overall quality experience



Introduction

• This presentation will explore the reliability, availability and defect rate attributes of product quality – What the attributes mean – How they are measured– How they impact the product performance and the

customer



Introduction

• This presentation will also cover some of the methods and tools that product developers and manufacturers use to ensure desirable quality results.

MTBF

HA

SPC

DFMMTTR

ELF

ALT

RedundancySix Sigma



Agenda

• Reliability• Availability• Quality (Defect Level) Time

Monthly Failure

Rate

0.01

0.1

1

10

100

1000

1,000 10,000 100,000 1,000,000MTBF

MT

TR

0.99 0.999 0.9999 0.99999 0.999999Total Defects Per Unit (TDU)

0.00

0.04

0.08

0.12

0.16

0.20

Time



Product Focus

Computer SystemsPrinted

Circuit Assemblies



Reliability & Availability

Defect Prevention and Elimination

Quality Life Cycle of a Product

Useful LifeIntegration, Deployment& Early Life

Supplied Materials &

Parts

ManufactureDesignEnd of Service



Product Reliability



Product Reliability• Reliability is an expression of the probability

that a part or system will function without failure in a defined environment for a designated period of time.– Example: Computer system X operating at 25 degrees C

has a 99% likelihood of functioning for a year without failure.

• Reliability Objective: Design and manufacture product that will continue to function with minimal failures for the intended life of the product



Product Reliability Metrics

• Failure Rate– Commonly expressed as % per month or % per year

• Mean Time Between Failures– Reciprocal of failure rate; Usually expressed in hours

• Mean Time To Failure– Typically used for non-repairable product

Number of FailuresUnits x Time

=

Units x TimeNumber of Failures

MTBF =

(Time to Failure)Units

MTTF =



Product Reliability Metrics - Examples• Failure Rate

= Number of Failures = 24 failures = 2.4% per year

( Units x Time ) 1000 units x 1 yr

• Mean Time Between FailuresMTBF = ( Units x Time ) = 1000 x 8760 hrs = 365000 hours

Number of Failures 24 failures



Product Failure Rate Over Time: Early Life Failures and the Bathtub Curve

Time

Monthly Failure

Rate

Early Life Failures

Steady State

Wear-out




Time

Monthly Failure

Rate

Inherent Failure Rate Latent Defects

Early Life Failures

Steady State

Wear-out



Product Return Rate Trend

Months Since Product Shipment

% Returned

Per Month

Early Life Failures and Possible

Design or Materials Problems Exposed

Escaping Defects,

Integration and

Application Problems

Stable Operating

Period

Wear-out Phase is well beyond this time

scale



Product Field Return Trends

Time

Cu

mu

lati

ve

% R

etu

rns

Ob

se

rve

d M

TB

F

Cumulative Returns Observed MTBF

In general, after the initial ramp-up, return rate continues to drop throughout the first several years after product shipment

Observed MTBF increases with time

Return Rate decreases with time



Predicting Product Reliability

• Reliability Predicted using models– Based on expected reliability of the components used in

the higher level product

• Demonstrated via ALT (Accelerated Life Testing)– Stress test a sample of the product

• Actual or Observed– Track field failure and returns data– Compare new designs to similar existing designs



Accelerated Life Test (ALT)

• ALT is a process by which products are subjected to increased stress factors for controlled time periods– Temperature

– Vibration

– Humidity

– Voltage

– Power, etc.

• Multiple years of normal product life are compressed into a several week period.

• ALT testing enables a product developer to simulate potential product field-failure modes.



ALT

• ALT may expose:– Hardware failures - True defects (repairable)– Design Failures - Failures due to design problems– Component Failures - Failures due to component

deficiencies– Integration Failures - Failures resulting from integration

with other products



Accelerated Life Test (ALT)Example Test Process

A functional test is conducted between test phases

End

Thermal Shock Cycle

+85C/-40C time soak

No power applied

Random Vibration

6G’s RMS 20-2000 Hertz random time horizontal

time vertical

Temperature Cycle continuous time cycles

–20C to +75COr T of 95C

Power Soak Cycle

75C/85% RH

Functional Test

45C/85% RH

Start

Acceptance Test

0C 4.75 & 5.25 VDC

50C 4.75 & 5.25 VDC

45C/85% RH



Environmental DVT (Design Validation Test)

• The purpose of Environmental Design Validation Testing (DVT) is to validate the hardware design and manufacturing process by stressing the product in various environmental conditions.



Environmental DVT (Design Validation Test) Example Test Process

Sinusoidal Vibration

16G’s RMS 5-12000Hz

Horizontal &Vertical

Thermal Shock Cycle

+85C/-40C No Power

AcceptanceTest

at Ambient Temperature to Verify Product

Prior to Testing

End

Test at Ambient Temperature

to Verify Thermal Shock and Sinusoidal Vibration Did

Not Cause Defects

Temperature Cycle

Continuous 2-Hour Cycles

5o of Datasheet

Temperatures

Power Cycle with Temperature

Cycles and Voltage Margins

Verify Product Initializes on Each

Power Cycle

Voltage Margins with Temperature Cycles

3.3v/3.4v/3.3v/3.2v Cycles5v/5.2v/5v/4.8v Cycles

12v/12.6v/11.4v Cycles-5C/+55C Cycles

Start



Other Tests: Compliance, Regulatory, Safety, Packaging, etc.

• Drop Tests (Packaging)• Radiated & Conducted Emissions• Electrostatic Discharge Immunity (ESD)• Surge• Voltage Dips and Interruptions • Safety



Product Availability

• Probability that a product is operational at a given time

High Availability High Availability Five 9’s Five 9’s 99.999% 99.999%



Product Availability Metrics

(Time to Repair)Number of Failures

MTTR =

Availability = 1 - Unavailability

MTBFMTBF + MTTR

Availability =

Under steady-state conditions:

Where:

The product is either available or unavailable:



Product Availability Calculation

0.01

0.1

1

10

100

1000

1,000 10,000 100,000 1,000,000MTBF

MT

TR

0.99 0.999 0.9999 0.99999 0.999999



Availability: 5 Nines Examples

0.01

0.1

1

10

100

1000

1,000 10,000 100,000 1,000,000MTBF

MT

TR

0.99 0.999 0.9999 0.99999 0.999999

8760 Hours

5.26 Minutes (0.0876 Hours)

438000 Hours (2%/yr)

4.38 Hours



Availability From An End-User Perspective• Probability that a product is available for use

when the user wants to use the product• Availability is often dependent on both the

end-user product and the service provider– Example: Each of these factors contributes to cell phone

availability from the end-user perspective• Cellular phone is functional• User has a charged battery• Network coverage exists • Network is functional

NetworkNetwork



Design for Increased AvailabilityEnd-User Consumer Product• Increase reliability (MTBF) and reduce latent defects• Provide a back-up for common failure modes

– Battery back-up in plug-in alarm clock for power outages

• Provide fast repair or replacement– Cellular phone failure

• Slower: Send in for repair and return. • Faster: Delivery of replacement phone.• Even Faster: On-site spare.

– Flat tire• Slower: Call for tow service.• Faster: Replace flat tire with spare.• Even Faster: Tire that indicates failure, but does not go flat

right away.



Availability From A System Perspective

• Percentage of time a system is available for use• Key factors

– Failure Rate of each system module

– Impact of a module failure on the overall system

• Single point of failure causes system level failure– Time to repair or replace faulty product determines downtime

• Module failure causes loss of certain functions– May be able to continue to use

• Module failure does not result in system level failure– Redundancy and fault resiliency

– Time to Repair or Restore full system functionality



Design for Increased AvailabilitySystem Product• Use redundancy within the system so a single module failure will

not cause a system failure; all system components have back-ups

3 redundant power supplies (2+1)

3 redundant cooling fans (2+1)

2 redundant storage drives

Sets of redundant process boards

Hot swap Hot swap capabilitycapability



Design for Increased AvailabilitySystem Product

• Allow for very rapid return to service– Software fault management

• Software manages system resources to work around faulty module and to restore operation to the replacement module

– Hot swap replacement• System remains functional during replacement

operation– Redundant system as standby

• Hot standby with immediate switchover



Product Selection For Availability

• Determine application requirements– Impact of a failure during operation

• Service options– Attended vs. remote site

• For example, office vs. mountain top product location– Cost and time of service vs. cost of other designed in

robustness options

• Select products and suppliers that can hit the quality, reliability and availability requirements



Product Quality

• Objective:

Design, manufacture

and deliver defect

free product that

meets defined

specifications and

customer

requirements



Manufacturing QualityDefinitions

• Unit– The item produced or processed.

• CTQ (Critical To Quality)– Characteristics which are key to the customer’s perception of

quality.

• Defect– An unacceptable variation of a quality characteristic from its

intended level.

• Opportunity– Any action in which the product, service, or information is

handled.– Any action performed or neglected during the creation of a unit

of work.



Manufacturing Standards

• Examples of manufacturing quality standards – IPC-A-600 Acceptability of

Printed Boards– IPC-A-610 Acceptability of

Printed Board Assemblies– IPC R-700 Guidelines for

Modification, Rework and Repair of Printed Boards and Assemblies



Manufacturing TestingPrinted Circuit Board Example

• In-Circuit Test (ICT), sometimes using a bed-of-nails fixture, tests the product for electrical properties.

– Shorts, Opens, Parts, etc.

• Functional Test is performed on the completed product assembly to verify the functional characteristics of the product.

– Use on-board or external diagnostics and relevant operating systems.– Intent is to simulate actual customer operation of the product as closely

as possible.

• Automated Optical Inspection (AOI) is used to verify all parts are on the board in the correct position.

– Supplements human inspection, which is not capable of detecting all defects



Manufacturing Process: Delivered Defects

• No test or inspection is 100% effective in finding defects.– For example, a single visual inspection may only identify 70% of

the actual defects

• Multiple, successive visual inspections will find more defects, but this adds cost and time

• Delivered defects escape the test and inspection processes within the factory.




Time

Monthly Failure

Rate

Inherent Failure Rate Latent Defects

Early Life Failures

Steady State

Wear-outProportional to Manufacturing Defects

ELF Caused by Latent Defects



Manufacturing Process

• Reducing the TDU in the entire manufacturing process will:– Reduce the cycle time per unit

• Less rework, test and inspection required– Reduce delivered defects– Reduce early life failure rate– Decrease warranty cost per unit

• Total Defects Per Unit (TDU or DPU)Total Number of Defects

Number of UnitsTDU =



Design Process: Long-Term Reliability

• The greater the design margin, the lower the inherent failure rate.

• Electronic products, with superior design margin, built without defect, and operated within design limits…

will operate without failure

for many, many years



Product Sigma, a Figure of Merit

• From DPMO, we can calculate Sigma for a product.– Sigma is a standardized method to measure and compare the

quality of any product or process, regardless of complexity.

• Defects Per Unit could be expected to be proportional to complexity of the unit

• Complexity is directly proportional to the number of opportunities to create a defect

• To normalize products of different complexity, use

Total Number of DefectsOpportunities Per Unit x Number of Units

DPMO = x 1,000,000



Product Quality Metrics: TDU & DPMO

Total Defects Per Unit (TDU)

0.00

0.04

0.08

0.12

0.16

0.20

Time

Defects Per Million Opp. (DPMO)

0

5

10

15

20

25

Time



Design For Manufacturability (DFM)

• Manufacturability is the ability to reproduce, identically and without waste, units of product so that they satisfy all of the customer’s physical and functional requirements.

• The greater the design margin, the lower the Total Defects Per Unit (TDU).

• Design margin is measured by Capability Index (Cp)

Maximum Allowable Range of CharacteristicNormal Variation of Process

Cp =



Statistical Process Control (SPC)

• Process characteristics and outcomes contain variability over time.

• Statistical Process Control is used to– Track the process variation,– Determine the current amount of expected variation,– Identify when the variation exceeds statistical limits, – Provide insight into how to reduce the process variation, thus

increasing the process capability (Cp)

• SPC control charts show the tracked values and statistical limits– Goal is to stay inside the limits and to reduce the limits by

continuously decreasing variability



Reduce the variation and center the process to eliminate defects

Need to center the process meanNeed to reduce

the process variation

Six Sigma process, centered on target



SummaryQuality Life Cycle

Useful LifeIntegration, Deployment& Early Life

Reduce Variation for

Fewer Defects

ManufactureDesignEnd of Service

Have Fewer Escaping

and Latent Defects

Achieve Higher MTBF

and Availability

Longer Life with Lower

Cost

Create Reliable and Manufacturable

Designs

DFM SPCDVT HA MTTR6 ALT

Reliability & Availability

Defect Prevention and Elimination



Summary

• Start with a Robust Design – Manufacturable (DFM)– Reliable (DVT, ALT, MTBF)– Repairable (MTTR)

• Control the variability in the factory (Cp, SPC)– Lower TDU

• Which results in…– Fewer latent defects & early life failures– Higher MTBF– Higher Availability

• High MTBF & Low MTTR High Availability– Lower costs and higher Customer Satisfaction

sk 09-sep-2002 motorola general use, kelly_quality_lhc motorola and the stylized m logo are...

Documents

lhc motorola

motorola general use

product developers

product performance

us patent trademark

service names

respective owners

desirable quality results