Defect Description
Insufficient solder that weakens a solder joint leads due to a reduction in area. The change in the solder fillet shape also leads to a change in the path of maximum shear strain in a solder joint due to differential thermal expansion, which can alter the crack propagation path to a greatly reduced cross-sectional area [1].
Defect Formation Process(s)
Insufficient solder can be a result of non-optimized soldering process and different factors such as the assembly design, assembly process, shape of solder wave, etc. [1]
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List of Tests to Precipitate this Defect |
Failure Acceleration |
Likelihood to Precipitate this Defect (condition) |
Failure Mechanism(s) |
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Thermal Shock |
• Cyclic thermal mechanical stress accelerates crack initiation or growth of the weak solder joint • Thermal mechanical stress causes fracture of the weak solder joint |
✔ |
Thermal Faitgue Thermal mechanical Oberstress |
|
Random Vibration (RS/ED) |
• Random Vibration accelerates fatigue cracking of the weak solder joint • Random Vibration can cause fracture of the weak solder joint |
✔/✇ |
Mechanical Fatigue Mechanical Overstress |
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Combined Environment |
• Combination of Thermal Shock and Random Vibration |
✔ |
Combination of Thermal Shock and Random Vibration |
|
Bend Test |
• Bending can cause fracture of the weak solder joint |
✇ |
Mechanical Overstress |
References
[1] Hillman, C., Rogers, K., Dasgupta, A., Pecht, M., Dusek, R., & Lorence, B., “Solder failure mechanisms in single-sided insertion-mount printed wiring boards.” Circuit World, pp. 28-38, 1999
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