Power module packaging and reliability
How dies, substrates and housings are assembled into a module that must last the life of the car.
- Explain power module packaging and reliability at engineering level
- Read the numbers that define the behaviour
- Apply the idea to a real drive system
Overview
An automotive power module is expected to survive fifteen years and hundreds of thousands of thermal cycles without a single failure. That reliability is designed into the packaging as much as into the semiconductor itself.
In depth
Aluminium wire bonding
The traditional interconnect between die and substrate; simple and cheap, but a common failure point under thermal cycling.
Direct-cooled baseplates
Pin-fin baseplates in direct contact with coolant remove one thermal interface entirely, cutting junction temperature.
Sintered-silver die attach
Replaces solder with a sintered silver joint that tolerates far more thermal cycles before fatigue.
Double-sided cooling
Removing heat from both faces of the die roughly doubles the achievable current density for the same temperature rise.
Packaging check
- 1
Which die-attach technology best resists thermal cycling fatigue?
- 2
Double-sided cooling removes heat from both faces of the die.
Key takeaways
- Automotive power modules must survive hundreds of thousands of thermal cycles.
- Wire-bond lift-off and solder fatigue are the classic failure modes packaging aims to defeat.
- Direct cooling and sintered-silver attach are the current state of the art in reliability.
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