Enhancing Reliability through HALT

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Enhancing Reliability through HALT
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• Introduction to HALT
• Benefits of HALT
• The HALT process

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Objective
HALT - Highly Accelerated Life Test TO IMPROVE
RELIABILITY reduce warranty claims release
product to market earlier extend warranty periods
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Benefits, Economic Rationale
Finding design weaknesses as early in the product
design cycle as possible, can save a substantial
amount of money.
If X 40 for example, the cost to find design
weakness on customer site is .
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Benefits, Cost Time
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
Presentation by Ronald Horrell, Chief of
Reliability
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Benefits, Faster Market Release for LESS
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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.

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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 products
life
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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
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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

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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 table 3 Ensure
adequate airflow within the product (modify the
case if required) 4 Verify Functionality 5 Run
HALT 6 Failure Analysis 7 Implement Corrective
Action 8 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
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HALT Application
Rapid thermal cycles between the operational
limits
Combination of rapid thermal cycles and vibration
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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

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How long does a HALT take?
3 to 5 Days!!!
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Distributions shown as Gaussian Distributions for
illustrative purposes only
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
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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
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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
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The link with HASS
HALT Knowledge
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The application of HALT and HASS plays a critical
role in improving the in-service reliability of a
product through better, more robust, designs and
manufacturing processes.
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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.

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