- Effect "What does it look like?"
- May appear as:
- In x-ray or optically it appears as a discontinuity (missing piece) in
the wire. Sometimes a melted ball is seen at each termination of the break.
- Can be associated with a carbonized epoxy sheath, electrical open,
intermittent open and/or gross functional failure
- Causes (What caused the damage?)
- Sustained high current or power dissipation
- Diagram or refer to HBM waveform or other waveforms
- Junction damage may have occurred first
- Refer to Junction damage section
- Metallization burn-out
-
Voltage >10v and Pulse width >1µsec but <10sec
- Sources (What generated the voltage spike)
- Humans
- Mis-orientation of IC
- Monitor for compliance to correct procedures
- Inadvertent application of voltage
- Check line test history for voltage surges or sustained high current
sources
- Machine
- Mis-orientation of IC
- Determine and monitor assembly process
- Inadvertent application of voltage
- Check for unregulated or faulty power supplies
- Environment
- Lightning strike, power supply surge/transient
- Device and application exposure to lightning and/or
power supply transients during test or assembly
- Latch-up condition
- Application and test procedures
- Manufacturing defects
- Metallization or polysilicon thinning
- Requires die-level investigation, i.e. component failure
analysis
- Methods for Investigation
- Look first at
- Quantify scope/size of problem
- Is it a sporadic occurrence?
- Does it happen on a recurring basis?
- Does it appear to be "batch" related?
- Most likely problem areas
- Electrical Test (Over-voltage; Voltage spikes; Power sequencing)
- Board or System Assembly (Mis-orientation of IC, subassembly, or
cabling; Hot-switching
- Also see the Junction Damage section
- Didn't find anything. Now What?
- Address any findings resulting from ESD survey or
process review
- ESD audit using spec: EIA 625
- Humidity survey (>40%RH)
- Grounding (human and machine)
- Packing materials
- Remove non-essential ESD-generating material
- ESD or static field sources
- Check application for inductors in proximity
- Supply line monitors
- Found something. Now what?
- Address any findings resulting from ESD survey or process review
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