Preventing Thermal Cycling and Vibration Failures

Presented by the well-known author and internationally recognized authority on electronic equipment

Prof. Dave Steinberg, P.E. - 2 days


OBJECTIVES

  • To understand how variations in thermal coefficients of expansion (TCE) can affect the magnitude of the displacements, forces, and stresses that are developed in electronic assemblies during thermal cycling environments.
  • To understand how resonant conditions can affect dynamic displacements, forces and stresses in electronic assemblies during different sine vibration, random vibration and environments.
  • To understand the concept of "damage accumulation" and how it can be used to determine the approximate fatigue life of various electronic assemblies due to different combinations of fatigue accumulated in thermal cycling, vibration and shock environment.

WHO SHOULD ATTEND

Designers, engineers and managers from all the following functions:

  • Quality Assurance
  • Reliability
  • Test Engineer
  • Research & Development
  • Product Design
  • Production & Manufacturing

COURSE OUTLINE

PHYSICS OF FAILURE IN ELECTRONIC SYSTEMS

  • Program Objective
  • Areas That Require Analysis And Evaluation
  • Environmentally Induced Failures
  • Reliability Perspectives, MTBF Versus Effective Operating Life
  • How Thermal Cycling Environments Affect Fatigue Life
  • Effects Of Thermal Expansion
  • Sine And Random Vibration Characteristics
  • Estimating The Fatigue Life Of Surface Mounted Devices
  • Combining Fatigue Damage From Many Different Environments
  • Sample Problems

MOUNTING METHODS FOR VARIOUS TYPES OF ELECTRONIC COMPONENTS

  • Different Types Of Electronic Components And PCB Mountings
  • Techniques For Attaching Surface Mounted And Through-Hole Devices To PCBs And Their Associated Problems
  • Mounting Components That Have Bottom Lead Wires
  • Problems With Mounting Small Axial Leaded Components
  • Areas Where Minor Structural Changes Can Produce Large Increases In Fatigue Life
  • Tips To Improve Heat Dissipation

THERMAL CYCLE CREEP AND FATIGUE FAILURES IN LEAD WIRES AND SOLDER

  • Solder Thermal Cycle And Vibration S-N Fatigue Curves
  • Solder Strain Fatigue Life Plots
  • Solder Creep With Constant Stress And With Constant Displacement
  • Solder Creep And Stress Relaxation
  • Solder Creep Stress Relaxation As A Function Of Time
  • Thermal Cycle Fatigue Life Test Data On Different Types Of Surface Mounted And Through-Hole Mounted Components

X-Y THERMAL EXPANSION DISPLACEMENTS AND STRESSES IN BOTTOM LEADED COMPONENTS

  • Sample Problem: Methods For Reducing Forces And Stresses In The Lead Wires And Solder Joints Of A Hybrid
  • Sample Problem: Shear Tear-Out Stress In A Through-Hole Solder Joint
  • Thermal Cycling Crowbar Effects In DIP Lead Wires

THERMAL CYCLING AND VIBRATION FATIGUE IN ELECTRONICS STRUCTURES

  • Effects Of Fatigue And Damage In Electronic Structures
  • Problem Areas In Predicting Vibration Fatigue Life Of Electronic Components
  • Comparing Vibration Test Data Failures With Finite Element Computer Analysis Data
  • Vibration Test Set Up With An Electrodynamic Shaker
  • Typical Failure Locations In DIP Lead Wires And Solder Joints
  • COMBINING THERMAL CYCLING AND VIBRATION FATIGUE DAMAGE
  • Alternating Stress Superimposed Upon A Steady Stress
  • Vibration Test Data Failures In Pin Grid Array Wires At Low Temperatures
  • Combining Thermal Cycling And Vibration Damage
  • Miner's Combined Cumulative Fatigue Damage Criteria
  • Integrity Driving Geometric Factors That Influence Fatigue Life
  • Tension, Torsion And Bending Stresses In 40-Pin DIP Wires

COMBINING THERMAL CYCLING AND VIBRATION FATIGUE DAMAGE

  • Alternating Stress Superimposed Upon A Steady Stress
  • Vibration Test Data Failures In Pin Grid Array Wires At Low Temperatures
  • Combining Thermal Cycling And Vibration Damage
  • Miner's Combined Cumulative Fatigue Damage Criteria
  • Integrity Driving Geometric Factors That Influence Fatigue Life
  • Tension, Torsion And Bending Stresses In 40-Pin DIP Wires

DISPLACEMENTS, FORCES AND STRESSES IN AXIAL LEADED COMPONENT WIRE FRAMES DUE TO X-Y THERMAL EXPANSIONS

  • Thermal Expansion Model
  • Use Of Superposition Method
  • Application Of Castigliano's Strain Energy Theorem
  • Samples Of Spread Sheets For Lead Wire Forces And Stresses
  • Samples Problems To Illustrate Methods For Reducing Forces And Stresses

THERMAL CYCLING STRESS FAILURES IN SURFACE MOUNTED COMPONENTS

  • Solder Shear Strain In Surface Mounted Components
  • The U.S. Air Force Avionics Integrity Program To Improve The Reliability Of Electronic Equipment
  • Predicting The Approximate Fatigue Life In Electronic Assemblies
  • Accelerated Life Testing Methods
  • Thermal Cycling Tests
  • Ceramic Chip Carrier And Plastic Chip Carrier Components
  • Cumulative Damacre Concepts For Estimating The Fatigue Life
  • Sample Problems

VIBRATION AND NATURAL FREQUENCIES OF SIMPLE ELECTRONIC STRUCTURES

  • Sample Problems To Illustrate Different Modes Of Resonant Frequencies
  • Desired PCB Resonant Frequency For A 10 Million Cycle Fatigue Life
  • The Most Important Relation In Dynamics
  • How The Component Location And Orientation On A PCB Affect The Fatigue Life
  • Test Data Of PCBs And Electronic Boxes
  • Case History Of A Failed Die Bond Wire Inside A Hybrid

RELATIVE DYNAMIC DISPLACEMENT BETWEEN THE COMPONENT AND THE PCB PRODUCING STRAIN IN THE LEAD WIRES

  • Derivation Of The Displacement Equation
  • Sample Problem To Determine The Relative Displacement Between The DIP And The PCB
  • Application Of Castigliano's Strain Energy Theorem To Derive The Lead Wire Stiffness With A Small Kink And Compare With Results Of Finite Element Analysis
  • Estimation Of Fatigue Life

VIBRATION AND THERMAL STRESSES IN THE LEAD WIRES AND SOLDER JOINTS OF A TRANSISTOR MOUNTED ON A PCB

  • Fatigue Life Dynamic Analysis
  • Derivation Of Thermal Expansion Equilibrium Equations
  • Analysis Of The Tensile Stresses, Shear Stresses And Fatigue Life
  • Sample Problem To Study Failure During Sinusoidal Vibration

FINITE ELEMENT MODELING METHODS, TECHNIQUES AND PROBLEMS

  • Finite Element Methods (FEM) For Accurate Prediction Of Resonant Frequencies, Forces And Stresses
  • Discussions Of Different FEMs
  • Various FEMs Of Different Types Of Solder Joints
  • Finite Element Model Showing Stresses In DIP Lead Wires

CASE HISTORIES OF FAILURES AND FAILURE ANALYSIS

  • Failures Of Small Ceramic Chip Resistors And Capacitors
  • Failures In Small Axial Leaded Through-Hole Components
  • Surface Mounted Transformer Lead Wire Failures
  • Microprocessor Lead Wire Solder Joint Failures
  • Relay Vibration Failures And Possible Screening Methods
  • Hybrid Shock Failure Of Internal Die Bond Wires
  • Cracked Casting Failure Analysis
  • Failure Analysis Of A Small Shaft

CONNECTOR WEAR AND FRETTING CORROSION

  • Connector Materials And Protective Coatings
  • Visual Inspection Of Failed Connector Pins
  • Non-Destructive Chemical Test
  • Connector Contact Resistance Test Set Up
  • Connector Contact Vibration Test Set Up
  • Test Data Of Different Connector Wear Curves

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