- Effect "What does it look like?"
- May not be visible
- Not visible unless device has been deprocessed.
- May look like a "pin-hole" or tiny dot at 3000x
- Causes (What caused the damage?)
- Voltage spikes
- Diagram or refer to HBM waveform or other waveforms
- Greater than 100V and less than 1 µsec (pulse width)
- Reference: Intel web site (www.intel.com)
- Pulse width between 200 ps and 200ns
- Ref: Smith, J.S., "Electrical Overstress Damage in Microcircuits", RADC #11.
- Sources (What generated the voltage spike)
- Humans
- Handling by un-grounded personnel
- Insufficient training or certificate program
- Uncontrolled work flows / processes
- Current procedures or practices not ESD compliant
- Machine
- Design
- PCB design and layout with ESD suppression
- Improperly grounded
- All components contacting IC or PCBs must be conductive and
connected to ground
- All components contacting IC or PCBs must be conductive and
equi-potential to ground
(ie. Phenolic spacers in a handler; Suspect any non-metallic piece
- Soldering Irons (ie. Too high resistance of tip to ground;
Three prong electrical plug.)
- Field Inductance or EMI
- Arcing; CRT related items; Electric motors; Microwave sources, RF sources
- Environment
- Weather
- Lightning strikes; Low humidity (<40RH)
- Triboelectric materials
- Non-conductive table tops, wall panels, floor.
Packing & transport materials. Styrofoam coffee cups.
- Resistive ground references
- ESD ground common with facility ground
- Manufacturing defects
- Inherent design weakness
- Oxide defect
- crystalline; particulates
- 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
- Is there adequate ESD training?
- Are ESD control components maintained?
- Are there unwanted voltage spikes in Electrical Test?
- Are the machines properly grounded?
- Did any of the following occur?
- Non-standard process handling (ie. re-work, off-line sampling)
- Process or material changes prior to recent events (ie. ESD component or
raw material changes; Power disruptions to plant or assembly line)
- 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?
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