Power Module Substrate Electrode Stack for Low-Damage Wire Bonding
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Solution Overview
Problem
The increasing trend towards higher voltages, larger currents, and faster switching in power semiconductor elements leads to greater damage during wire bonding, necessitating a technique to further reduce damage to the power semiconductor element.
Innovation Solution
A substrate for a power module with an insulating plate and a three-layer electrode portion structure, comprising a contact layer, a protective layer made of conductive ceramic, and a connection layer, where the protective layer has a higher hardness than the contact and connection layers, to absorb pressure and reduce heat conduction during wire bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of bonding wires is increased to handle higher voltages and currents, then the power handling capability is improved, but the damage to the power semiconductor element during wire bonding increases
Solution Approach 1:
A protective layer is introduced as an intermediary between the bonding wire and the power semiconductor element. This protective layer absorbs the pressure and mechanical stress during wire bonding, preventing direct damage to the element while allowing the bonding process to proceed with multiple wires for higher power handling.
Solution Approach 2:
The protective layer is applied beforehand to the power semiconductor element to cushion against the mechanical stress that will occur during subsequent wire bonding operations. This pre-protection enables the use of multiple bonding wires without increasing damage risk, thus improving power handling capability safely.
2Strength
If a hard protective layer is applied to reduce damage during wire bonding, then the resistance to mechanical stress is improved, but the heat conduction from the bonding wire to the element increases
Solution Approach 1:
The protective layer's physical parameters are optimized to achieve a balance: it has sufficient hardness to resist mechanical stress during bonding, but its thickness and material properties are controlled to limit thermal conduction. This allows the layer to protect against damage while minimizing energy loss through heat transfer.
Solution Approach 2:
The protective layer provides localized mechanical protection exactly where the bonding wire contacts the element, without requiring a thick or extensive coating that would impede heat conduction. The protection is precisely where needed, maintaining thermal efficiency while providing necessary mechanical strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The substrate effectively reduces damage to the power semiconductor element by minimizing pressure and heat transmission during wire bonding, thereby suppressing cracks and fissures.
Implementation Method 1
the protective layer has a higher hardness than the contact layer and the connection layer, to absorb pressure and reduce heat conduction during wire bonding
Implementation Method 2
the protective layer has a higher hardness than the contact layer and the connection layer, to absorb pressure and reduce heat conduction during wire bonding
Data Source
AI summary
A power module substrate according to the present disclosure comprises: an insulating plate; a plurality of surface patterns provided on the surface of the insulating plate; a power semiconductor element connected to one surface pattern among the plurality of surface patterns; an electrode unit provided on the upper surface of the power semiconductor element; and a bonding wire connected to both the electrode part and another surface pattern that is different from the one front surface pattern among the plurality of surface patterns. The electrode part comprises: a contact layer that is formed from a metal and is provided on the upper surface; a protection layer that is layered on the contact layer; and a connection layer that is formed from a metal, and is layered on the protection layer in a state where said connection layer is connected to the bonding wire. The protective layer contains a highly electrically conductive ceramic that is harder than the contact layer and the connection layer.