Defect Description
Protrusion of glass fiber in the board laminate into PTH walls that affects PTH plating thickness and can contribute to PTH cracks [1]
Defect Formation Process(s)
Possible causes for this defect can be process control variability during hole drilling, hole preparation or application of flash copper [1]
|
List of Tests to Precipitate this Defect |
Failure Acceleration |
Likelihood to Precipitate this Defect (condition) |
Failure Mechanism(s) |
|
Thermal Shock |
• Cyclic thermal mechanical stress accelerates crack initiation or crack growth at the protrusions where local stress concentration is high • Thermal mechanical stress causes fracture of the copper plating at the protrusions where local stress concentration is high |
✔ |
Thermal Fatigue Thermal Mechanical Overstress |
|
Random Vibration (RS/ED) |
• Random Vibration accelerates crack initiation or crack growth at the protrusions where local stress concentration is high • Vibration causes fracture of the copper plating at the protrusions where local stress concentration is high |
✔/✇ |
Mechanical Fatigue Mechanical Overstress |
|
Combined Environment |
• Combination of Thermal Shock and Random Vibration |
✔ |
Combination of Thermal Shock and Random Vibration |
|
Bend Test |
• Bending can cause fracture of the copper plating at the protrusions where local stress concentration is high |
✇ (Defect at a location with significant strain due to bending) |
Mechanical Overstress |
[2]
References
[1] Tulkoff C., Hillman C., “Reliable plated through via design and fabrication.” DFR Solutions
Permission for pictures
[2] Tulkoff C., Hillman C., “Reliable plated through via design and fabrication.” DFR Solutions
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