Power semiconductors

What is a typical failure seen in power cycling tests, which repeatedly heat and cool power modules?

  1. ABond wire lift-off and solder layer cracking caused by differences in thermal expansion coefficients
  2. BA change in chip color
  3. COnly gate oxide breakdown
Show answer and explanation

Answer: A. Bond wire lift-off and solder layer cracking caused by differences in thermal expansion coefficients

Power modules combine materials with different thermal expansion coefficients, such as silicon or SiC chips, aluminum wires, solder and substrates. Repeated temperature changes from current flow stress the interfaces, causing wire bonds to lift off and solder layers to crack. This is one of the main factors determining lifetime.

  • A. Correct. Wire lift-off and solder cracking from thermal expansion mismatch.
  • B. Color change is not a failure criterion.
  • C. Oxide breakdown is not a typical power cycling failure.
Practice this topic Back to topic

More Power semiconductors questions

  1. In packages for fast-switching power devices, what is the purpose of a dedicated source terminal for the gate-drive return (Kelvin source)?
  2. Which circuit uses a diode and capacitor to create a gate voltage above the supply to drive the upper (high-side) n-channel MOSFET of a half bridge?
  3. In Baliga's figure of merit, used to compare materials for unipolar power devices, which material property has a particularly strong effect?
  4. What is the main reason SiC (silicon carbide) is advantageous over Si for high-voltage power devices?
  5. Which correctly describes an IGBT?