Enhancing

Reliability through

HALT

Introduction to HALT

Benefits of HALT

The HALT process

Objective

HALT - Highly Accelerated Life Test

TO IMPROVE RELIABILITY

reduce warranty claimsrelease product to market earlier

extend warranty periods

Benefits, Economic Rationale

Finding design weaknesses as early in the product design cycle as possible, can save a

substantial amount of money.

~ Hiroshi Hamada, Ricoh Chairman

£X design phase £5X before procurement £11X before production £486X before shipment £19,714X on customer site

If £X = £40 for example, the cost to find design weakness on customer site is …….

Benefits, Cost & Time

Product #1 -Product #1 -HALT ProcessHALT Process

• 3-5 days to complete

• 1 integrated test chamber • 3 test specimens• no vibration fixture

Product #2 -Product #2 -Traditional Traditional MethodsMethods• 7 months to

complete

• Misc test chambers• 2 test specimens• 2 vibration fixtures

Conclusion: HALT provided faster time to market (reduction in test time), reduced engineering costs, and better results than traditional testing methodologies.

Information from United Technologies Presentationby Ronald Horrell, Chief of Reliability

Benefits, Faster Market Release for LESS

Market Release

Time

1 2 3

SpendingRate

0

1

2

3

4

5

6

4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Savings

HALT

Market Release

Benefits, Overview

• Quickly discover design & process flaws.• Evaluate & improve design margins.• Reduce development time & cost.• Eliminate design problems before

release to manufacturing.• Ship a mature product at market

introduction.• Use as a sustaining engineering tool to

evaluate impact of product modifications and cost reductions.

Definition of HALT

A process used during the

design stage of a product that provides a stringent

environment to force design and process maturity

Although normally

performed before manufacturing release, a HALT

can be beneficial in finding product

weaknesses at any point in a product’s life

Example

“No fault found” following product return

Dissatisfied client

Sample put through HALT which stresses the product

Identification of same failure as experienced by client

Equipment used

• Liquid Nitrogen Cooled rapid thermal transitions up to 60ºC/min on product

• Repetitive Shock Vibration

6 degrees of freedom 3 axes & 3 rotations, simultaneous broad frequency band (2-10,000 Hz)

• Combined Environment

Thermal and Vibration

• Liquid Nitrogen Cooled rapid thermal transitions up to 60ºC/min on product

• Repetitive Shock Vibration

6 degrees of freedom 3 axes & 3 rotations, simultaneous broad frequency band (2-10,000 Hz)

• Combined Environment

Thermal and Vibration

HALT Process

1 Test Plan Development (incorporate product specific stress sources,

develop functional tests with good coverage, define what constitutes a failure,...)

2 Determine method of attachment to vibration table3 Ensure adequate airflow within the product (modify the case if required)4 Verify Functionality5 Run HALT6 Failure Analysis7 Implement Corrective Action8 Verify corrective actions by repeating HALT

It is not just the testing - you also benefit from test plan development verification of the functionality and the analysis of the results

HALT Application

Apply Product Specific Stresses

oC

Hot thermal step stress.Begin at +30ºC, increase in 10º C steps. Continue until operating & destruct limits found.

Cold thermal step stress.Begin at + 20ºC, decrease temp in 10ºC stepsContinue until operating & destruct limits found.

6 DoF6 DoFVibeVibe

Vibration step stress.Begin at 5 Grms, step in 5 Grms incrementsContinue until operating & destruct limits found.Functional Testing

& Monitoring

Rapid thermal cycles between the operational limits

Combination of rapid thermal cycles and vibration

When failures occur during HALT

Stop test & record failure mode & stress level

Use isolation techniques to identify failure location

Determine root cause analysis ~ May require further investigation, or, Implement temporary fix

Continue testing to try to induce additional failures

Stop test & record failure mode & stress level

Use isolation techniques to identify failure location

Determine root cause analysis ~ May require further investigation, or, Implement temporary fix

Continue testing to try to induce additional failures

How long does a HALT take?

3 to 5 Days!!!

Not all examples of a product fail at the same level of stress, some are stronger than others. A distribution will

exist for each failure

Not all examples of a product fail at the same level of stress, some are stronger than others. A distribution will

exist for each failure

Distributions shown as Gaussian Distributions for illustrative purposes

only

Distributions shown as Gaussian Distributions for illustrative purposes

only

The above example could indicate where a ‘strong’ unit has been used during qualification and the results from this test has allowed market release but 5% of the units are weaker than the specification limit leading to a high early mortality

rate

The above example could indicate where a ‘strong’ unit has been used during qualification and the results from this test has allowed market release but 5% of the units are weaker than the specification limit leading to a high early mortality

rate

The example above shows how a failure distribution (A) is well above the product specification limit when new but due to aging, some of the product population becomes weaker

than the specification limit

The example above shows how a failure distribution (A) is well above the product specification limit when new but due to aging, some of the product population becomes weaker

than the specification limit

HALT Knowledge

HASSHASSHighly Accelerated Stress Screen

A process used in manufacturing, to allow discovery of process changes and prevent products with latent defects from getting into the field.

HASSHASSHighly Accelerated Stress Screen

The link with HASS

The application of HALT and HASS The application of HALT and HASS plays a critical role in improving the plays a critical role in improving the

in-service reliability of a product in-service reliability of a product through better, more robust, through better, more robust, designs and manufacturing designs and manufacturing

processes.processes.

Benefits, Overview

• Quickly discover design & process flaws.• Evaluate & improve design margins.• Reduce development time & cost.• Eliminate design problems before

release to manufacturing.• Ship a mature product at market

introduction.• Use as a sustaining engineering tool to

evaluate impact of product modifications and cost reductions.

Contact UsContact Us

TUV Product Service Ltd

Segensworth Road, Fareham, Hampshire, PO15 5RH, UK

Email: info@tuvps.co.uk

Web: www.tuvps.co.uk

Tel: +44 (0) 1329 443300

Fax: +44 (0) 1329 443421