Lecture 4 - Failure Mechanisms

Question 1

Define failure mechanisms

Answer 1

Are physical processes whose occurrence either lead to or are caused by stress agents (challenges), and may deteriorate the capacity of an item.

Question 2

What is failure mechanisms - mechanical?

Answer 2

• Modarres describes 3 classes
  Stress-induced
  – cause or are the result of localized stress (permanent or temporary)
  – e.g. elastic deformation, brittle fracture, buckling, yield, impact, ductile fracture
  Strength-reduced
  – Lead to a reduction of an item’s strength or endurance to withstand stress or damage
  – e.g. radiation embrittlement, fretting, wear, corrosion, cracking, diffusion, creep.
  Stress-increasing
  – Results in an increase in the applied stress
  – e.g. fatigue, radiation, thermal shock, impact, fretting

Question 3

What is failure mechanisms - electrical?

Answer 3

• Modarres describes classes
  Electrical stress
  – When subjected to voltage/ current/ electrostatic discharge levels higher than design
  – E.g. electrical overstress, electrostatic discharge
  Intrinsic
  – Related to the basic electrical activity of the device
  – e.g. gate oxide breakdown, ionic contamination,
  Extrinsic
  – Stem from issues with packaging and interconnections
  – E.g. corrosion, bonding failures, radiation

Question 4

What are the links between mechanism, causes and effect

Answer 4

REFER TO LAST SLIDE