HALT vs. ALTWhen to Use Which

Technique?

by

Mike SilvermanManaging Partner

Ops A La Cartemikes@opsalacarte.com

www.opsalacarte.com(408) 472-3889

Overview

HALT and ALT are two of the most popular testing methods but often times engineers are confused about which to use when.

OverviewHighly Accelerated Life Testing (HALT) is a great reliability technique to use for finding predominant failure mechanisms in a hardware product.

However, in many cases, the predominant failure mechanism is wear-out.

When this is the situation, we must be able to predict or characterize this wear-out mechanism to assure that it occurs outside customer expectations and outside the warranty period.

The best technique to use for this is a slower test methodAccelerated Life Testing (ALT).

Overview

In many cases, it is best to use both because each technique is good at finding different types of failure mechanisms.

The proper use of both techniques together will offer a complete picture of the reliability of the product.

HALTHighly Accelerated Life Testing

used for Product Ruggedization

ALTAccelerated Life Testing

used to Characterize Predominant Failure Mechanisms, Especially for Wearout

Comparison Between ALT and HALT

FAILURE TESTING

HALT

OBJECTIVES1. Root Cause Analysis2. Corrective Action Identification3. Design Robustness Determination

TESTING REQUIREMENTS1. Detailed Product Knowledge2. Engineering Experience

ALT

OBJECTIVES1. Reliability Evaluation (e.g. Failure Rates)2. Dominant Failure Mechanisms Identification

TESTING REQUIREMENTS1. Detailed Parameters

(a) Test Length(b) Number of Samples(c) Confidence/Accuracy(d) Acceleration Factors(e) Test Environment

2. Test Metrology & Factors(a) 4:2:1Procedure Or Other(b) Costs

ANALYTICAL MODELS1. Weibull Distribution2. Arrhenius3. Coffin-Manson4. Norris-Lanzberg

HALT on System ALT on System Fan

Combining ALT with HALTOften times we will run a product through HALT and then run the subassemblies through ALT that were not good candidates for HALT.

Developing ALT from HALTAnd at other times, we may develop the ALT based on the HALT limits, using the same accelerants but lowering the acceleration factors to measurable levels.

HALT on System ALT on System

Examples of Products for HALT and ALT

FanInfusion Pump

MedicalCabinet

Robot

These pictures are samples of products we have tested. These are not the actual products to protect the proprietary nature of the products we test.

Automotive Electronics

AutomobileCell Phone

Component

Hard Drive

Component

Temp/HumidityContamination, Package Hermeticity

Temp CyclingMismatch of Thermal Characteristics of Package Matls

VibrationDie Attachment, Bond Wires

High TemperatureAgingAccelerantCharacteristic

Automobile

Repetitive cycling testMechanical

Temperature, Vibration, Humidity Contamination

ElectronicsAccelerantTest

Fan

Temperature, Humidity, Contamination

Lubricant Longevity

Duty Cycle, Speed, Torque, Backpressure

SpinningAccelerantTest

Hard Drive

Temperature/VoltageBoard Derating

Non-Operational VibrationContamination on Head Surface

Duty Cycle, Force, AngleConnectors – Power, Data

Duty Cycle, Start/Stop, Speed, Temperature?, Vibration?

Head SpinningAccelerantTest

Robot

Duty Cycle, Speed, TorqueZ-Stage (up and down)

Temperature, AltitudeVacuum Hold-down

Duty CycleRepeatability

Duty Cycle, Speed, TorqueArm Movement (side to side)

AccelerantTest

Automotive Electronics –

GPS Receiver

Duty Cycle, Force?, AngleButton Pushing

Temperature, Vibration, Humidity Contamination

Electronics

AccelerantTest

Infusion Pump

Duty Cycle, Rate, Plunger ForcePumping

Duty Cycle, Force, AngleConnectors – Battery, Charger, Pole Clamp, IV Line, Cassette

Duty Cycle, Location, Force?Touchscreen

Duty Cycle, Deep Discharge, Speed of Charge

Battery Charging

AccelerantTest

Drawer for Medical Cabinet

Duty Cycle, Force, ContaminationLocking Mechanism

Duty Cycle, Force, AngleOpening/Closing of Drawer

AccelerantTest

Cell Phone

Duty Cycle, Force, AngleConnectors – Headset, Battery, Charger

Duty Cycle, Location, Force?TouchscreenDuty Cycle, Force?, AngleButton Pushing

AccelerantTest

SummaryWhen wear-out is not a dominant failure mechanism, HALT is an excellent tool for finding product weaknesses in a short period of time.

SummaryWhen wear-out is a dominant failure mechanism, we must be able to predict or characterize this wear-out mechanism to assure that it occurs outside customer expectations and outside the warranty period.

ALT is an excellent method for doing this

Next StepsReview the electrical portion of your product and determine what stresses can be used to accelerate these failures –Concentrate on HALT style testing.

Review the mechanical portion of your product and determine what stresses can be used to accelerate these failures –Concentrate on ALT style testing.

Write a test plan that incorporates both

…and of course, we can help you with all of these

ANNUAL RELIABILITY SYMPOSIUMMay 7-11, 2007Santa Clara, CA

1) Design for Reliability (DfR) - Learn the building block tools for reliability during the concept and design phase. May 7-8

2) Design for Manufacturability (DfM) - Learn what tools are needed to produce great products with high quality. May 9

3) Design for Warranty Cost Reduction (DfW) - Introduces a proven warranty event cost model that helps identify warranty cost red. Solutions. May 10

4) Design of Experiments (DoE) - Includes basic statistics behind a DOE as well as a workshop inwhich we perform a DOE on a specific product. May 9-10

5) Best Accelerated Reliability Test Methods: HALT, ALT, and RDT – This course will review each of the best Accelerated Test Methods and show when to use each. Great for those already familiar with the concepts of HALT as well as those that are newcomers to the field. May 7-8

6) Fundamentals of Climatic Testing - Review the different types of climatic tests—temperature, humidity, altitude, rain, solar, salt/fog, & more. May 9-10

7) Software Reliability - Highlights “best practices” in S/W Reliability and explains their application & positive impact to each of the development life cycle phases: Concept, Design, Implementation, & Testing. May 11

NEW TEST LAB

HALT and HASS Labs www.haltandhasslabs.com Ph: (408) 654-0499 Fx: (408) 255-5789 990 Richard Ave., Suite 101, Santa Clara, CA 95050

Ops A La Carte LLC is proud to announce that we now own and operate

HIGHLIGHTS ABOUT

• Tested over 500 products in over 50 different industries • Second oldest HALT facility in the world, established in 1995 (originally owned by QualMark) • Most experienced staff with over 50 years of combined experience in HALT and HASS • We only use degreed engineers to run all our HALT. • HALT equipment has all latest technology – only lab in region • Our HALT/HASS services are fully integrated with our other consulting services. • We provide HALT/HASS services on a world-wide basis, using partner labs for tests outside California.

990 Richard Ave., Suite 101 Santa Clara, CA 95050

(408) 654-0499

TEST LAB CAPABILITIES

HALT and HASS Labs www.haltandhasslabs.com Ph: (408) 654-0499 Fx: (408) 255-5789 990 Richard Ave., Suite 101, Santa Clara, CA 95050

HALT & HASS Labs adds two more pieces of Reliability Test equipment.

In addition to our two HALT chambers, we now have an electro-dynamic shaker capable of doing two axis sine and random, and we also have a Combined Temperature/Humidity chamber. Both chambers add versatility to the types of reliability tests we can perform.

HERE IS A LIST OF SOME OF THE SPECS WE CAN TEST TO:

• DO160 • IEC • IEEE • ISTA/ASTM • JEDEC • MIL-STD-810 • SAE • SEMI • Telcordia • and more