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Highly Accelerated Life Test (HALT)

Wayne Bradley8 April 2014

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Agenda

• HALT Definition• HALT Process• Defense Versus Commercial Industry Application• HALT Benefits• DoD HALT Implementation• HALT Versus Design Verification Test• Challenges To Implementing HALT In Defense

Industry• HALT Summary• HALT Discussions

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HALT Definition

• The Term HALT Was Coined in 1988 By Dr. Gregg K. Hobbs To Describe A Process Previously Referred To As "Design Ruggedization“.

• A Test Method That Utilizes Accelerated Stresses To Detect and Eliminate Design Weaknesses During The Product Design Phase

• Conducted Early In The Development Cycle• An Iterative Test Approach (Test-Analyze-Fix-Test) Used To:

• Define The Stabile Operating Limits• A Design Phase Best Practice

• Define The Material Limits• Identifies Opportunities For Increasing Design Margin Over

The Performance Specification

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HALT Process

• A Typical HALT Program Applies An Iterative Test Approach Where Hardware Is Exposed To Incremental Changes In Either Temperature Or Vibration Until A Failure Occurs.

• If The Hardware Returns To An Operational Condition Upon Return To The Previous Step’s Input Level, Then The Stable Operating Limit Has Been Reached.

• To Determine The Destruct Limits Of The Hardware, Testing Is Resumed And Continues Until A Failure Occurs Where A Repair Is Required To Make The Hardware Functional At That Input Level. The Failure Mechanism Is Diagnosed, Corrected, And The Process Is Repeated Until A Point Where Implementation Of A Fix Is Technically Or Economically Unfeasible.

• The Improvement In Design Margin Is Dependent Upon How Much Beyond The Stable Operating Limit The Test Is Taken And Whether Or Not Corrective Actions Are Implemented For The Failures Modes

Identified During The Test.

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Defense Versus Commercial

• Commercial Industry- Requirements Generated By Market Demands- Customers Have Alternative Sources For Goods/Services- Customer Pays Directly For The Product- Developer Controls The Requirements Placed On The Supply Base- Most Products Have Short Life Cycles With Rapid Introduction Of New

Capability• Defense Industry

- Requirements Generated By A Combat Developer Representing The Customer

- Customer Has A Single Source For Goods/Services- Customer Developed Requirements Are Used To Establish Budgets That

Pay For The Product Development and Production- Developer Controls Performance Specification. Lower Level

Requirements Controlled By Supply Base- Most Products Have Long Life Cycles With Slow Introduction Of New

Capability

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HALT Benefits

• Commercial Industry- Reduced Product Development & Design Time

– Product Reaches Market/Customers Faster- Increased Product Quality & Reliability - Increased Customer Confidence - Reduced Warranty Costs - Increased Profitability

• Defense Industry- Increased Margin Over Design Limits- Increased Component/Subassembly Reliability- Increased Confidence In A First Time Pass For System

Qualification- Potential Increase In System Reliability- Potential Reduction In Operation and Support Cost

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DoD HALT Implementation

SystemPerformance

Spec

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Prime ContractHALT

Requirements

Prime Item Development

Specs

2Tier 1

Suppliers Primary HALT Implementation

Sub Contracts

Possible HALT Implementation

Prime Contractor

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Indenture Level

HW

& T

est

Co

st -

$

1 – Part: A single piece, or two or more joined pieces.2 – Subassembly: Comprised of 2 or more parts. 3 – Unit: A functional item viewed as a complete and separate entity for purposes of manufacturing. 4 – Subsystem: An assembly of functionally related units. 5 – System/Vehicle: An integrated set of subsystems and units capable of supporting an operational role

Notional Data

Procuring Agency

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HALT Versus Design Verification Test

HALT DVT Stresses The Product Beyond Specification Limits

Verifies That The Product Meets The Specification

Stresses The Product Until Weak Points Fail

Verifies That The Product Will Function In Its Intended Environment

Determines Stabile Operating And Destruct Limits

Is Successful When Product Does Not Fail

Conducting HALT At Part and Subassembly Level Improves Probability Of Completing System Qualification

Without Discovery Of A Significant Design Flaw

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Challenges With Implementing HALT In Defense Industry

• Procuring Agency Requirements Are Limited To The System Level Performance And Control Of Critical Interfaces

• HALT Is Most Effectively Implemented At A Level Below What The Procuring Agency Has Contract Control

• Acquisition Guidelines Encourage s The Procuring Agency To Allow Maximum Latitude To Prime Contractor In Developing The Technical Design And Production Solutions

- Imposing Technical Requirements Tighter Than The Performance Specification Is Considered Gold Plating

• Maintaining Achieved Margin Over Performance Specification Is Difficult In A Competitive Environment Where Cost Is A Major Factor In Contract Award.

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HALT Summary

• While there are general guidelines for implementing HALT, it must be tailored for each application.

- Detailed Knowledge Of The Material Characteristics Is Critical To Understanding When HALT Process Has Achieved The Most Cost Effective Margin Increase

• HALT Is Ideally Suited For Hardware Such As Circuit Card Assembly.• Since Conditioning Environments Are Applied In An Accelerated

Manner, HALT Can Be Conducted In A Short Period Of Time.- Use of HALT Should Not Impact System Development Test

• Temperature and vibration profiles for HALT are not tied to the expected system operating and storage environmental limits.

- HALT Is A Discovery Test And Not A Verification Test• HALT Is Most Effective When Applied At A Level Where Design

Features Such As Vibration Dampeners And Heat Sinks Do Not Interfere With The Rapid Application Of The Conditioning Environment

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HALT Discussion

• How Do We Impose HALT Requirements At Suppliers That Force Increase Margin Over What Is Required To Meet System Performance Requirements?

• Once We Achieve Greater Performance/Margin At Suppliers Through HALT, How Do We Maintain It?