HALT vs. ALTWhen to Use Which
Technique?
by
Mike SilvermanManaging Partner
Ops A La [email protected]
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