1. HALT: Notebook Computer Case Study
Nate Drees
Dell Inc.

2. Objective Introduce HALT methodology
Provide information on specific implementation of HALT (notebook computers)
Illustrate examples of HALT-unique failures

3. What is HALT? Highly Accelerated Life Test
Key concept is combined stresses
Rapid Thermal Cycling and Vibration at a minimum
Can also include voltage, frequency, etc.
Margin test / Test to Failure
Goal is to quickly highlight design weaknesses on a small sample size.
Stresses often exceed expected field use or even specification

4. HALT Equipment Special Chamber Required
Capable of Rapid Thermal Transition
Rate in excess of 45°C/min
Requires close access to LN2
Capable of Random Vibration
6 degrees-of-freedom (not just z-axis) quasi-random vibration
Frequency range from ~2Hz to 10kHz
Vibration usually provided by circular arrangement of pneumatic hammers

5. HALT Procedure Setup Thermal Step-Stress Rapid Thermal Cycling
Vibration Step-Stress
Combined Stress Cycles

6. HALT Setup
Use external peripherals (mouse, KB, etc.) to monitor unit as testing is operational.
Mount an accelerometer on a flat PCB surface near the CPU.
Mount a thermocouple to the PCB, usually on an IC.
Use proper fixturing to mount the test unit to the chamber floor.
Fixture
Thermocouple
Accelerometer
Power switch

7. Thermal Step Stress

8. Rapid Thermal Cycling
Following Thermal Step Stress, some HALT methodologies call for 3 rapid thermal cycles.
Can help distinguish thermal cycling failures from thermal/vibration failures
Omitted at Dell, due to experience with standalone thermal shock chamber.

9. Vibration Step Stress

10. Combined Cycles

11. HALT Failure Case Studies
Next 3 slides contain actual HALT failures
All case study failures were detected during the development cycle
These were determined to be legitimate failures, based on historical data
HALT is the only test that detected these failures
These issues were corrected and regressed prior to releasing the product

12. HALT Failure #1
Failure Occurred during combined cycles at system level
Connecting tabs in battery pack fractured
This failure sparked interest in performing HALT at battery pack level

13. HALT Failure #2
Failure occurred during vibration step stress at system level.
Historical data shows hinge was never weak link.
Increased radius solved the issue.
Hinge has fractured at the thinnest cross sectional area between base and display attachment.

14. HALT Failure #3
Initial sample of LF motherboard produced numerous solder joint cracks in vibration step stress
Failures occurred at levels much lower than eutectic
HALT is therefore an integral part of LF qualification

15. References
Hobbs, Gregg K.: HALT and HASS, The New Quality and Reliability Paradigm:
GM Worldwide Engineering Standards GMW8287: Highly Accelerated Life Testing. February 2002.

16. Thank you
© 2005