HALT/HASS/HASA and Practical Design FMEA
(course HALT 534)

Day 1

FMEA Class Overview:
A Failure Modes & Effects Analysis (FMEA) is a structured method to study a design or process that seeks to anticipate and minimize unwanted performance or unexpected failures.
Functional Block Diagrams (FBD):
 Much like an operational flow diagram that emphasizes Inputs, Outputs and the Process flow of the device being FMEAed
Exercise & Review:
The class will develop a FBD in small teams for a device that is specified in the class.  Each team’s effort is reviewed by the class.
Fault Trees (FT):
Fault Tree is produced from the FBD with an easy-to-use Excel spreadsheet.
Exercise & Review
The class will develop a fault tree from the FBD using the Excel spreadsheet.  Each team’s effort is reviewed by the class.
Failure Modes & Effects Analysis (FMEA):
 An FMEA is produced to identify the weak areas in the product.  An action Item list follows to assign tasks for later corrective action.  Three areas are emphasized: Severity of the failure mode, Detectability of the failure before shipping, and probable occurrence of the failure mode in the field.
Exercise & Review:
In teams the class will develop an FMEA from the FBD and FT.  Each team’s effort is reviewed by the class.
Assign corrective action tasks:
The class will weigh the results of the FT and develop a list of what needs to be improved upon and what doesn’t

DAY 2

Highly Accelerated Life Test (HALT):
HALT Defined - Temperature/Vibration/Voltage Stress - Voltage Margining - Clock Rate Stress - Hard & Soft Failures - Combined Stress
The Number of Units required for HALT: 
One is not enough - You must test to failure - Quantity needed for HALT – Gold Unit - Time to perform HALT
HALT Planning:
HALT Planning Action Item List - Weekly Meetings
Fixturing:
Specific mechanical fixtures - Universal Fixtures - Subassembly - Full Unit
HALT Lab Requirements:
Liquid Nitrogen – Tank - Multiple Dewars - Nitrogen Hose - Nitrogen Gas Purge – Air Purge -      Power - Floor Space - Oxygen Detector(s) - Shop Air - Exhaust Air
HALT Mitigations to Isolate Test Areas:
Using Shop Air - Mitigation Boxes - Best RTV adhesives - Best tape for strapping DUTs
Recommended Tools:
Toolbox – Torque Wrench- Strobe Light – High Torque Power Drill – Digital Camera             Microscope
Liquid Cooling: 
Water - 3M Liquids (non HFC) - Chiller Requirements
HALT Report:
When Done - What is Included – Data Tracking Sheets

Day 3

Highly Accelerated Stress Screening (HASS):
Stress Levels Defined - Product Specification Range – Precipitation of Defects  - Detection Screen - HASS Profile - Number of Units HASSed before HASA
Proof of Screen (PoS):
Determining Acceptable Fraction of Life Removed - Number of Units Required - PoS on One Unit - PoS during HASS - Salted Samples (a discussion) - PoS in Manufacturing -      Pos Determined During HALT - PoS Specifications required in HALT Report
Highly Accelerated Stress Audit (HASA):
Determining Sample Size - Customer Requirements - Queuing Space (before Shipment) Corrective Action(s) - Stop Order (in manufacturing)

Open Discussion on Class Subjects and Concerns