Power Module Bond Encapsulation for Leak-Tight Cooling
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Solution Overview
Problem
Existing power semiconductor modules in electric vehicle inverters face challenges with reliable leak-tight seals and high thermal conductivity bonds, which can lead to damage and delamination due to elevated process temperatures.
Innovation Solution
A power module design featuring a semiconductor chip on a substrate with a lead frame and a bond layer connected to a base plate with cooling structures, encapsulated by a mold compound, providing a metallurgical seal and improved thermal dissipation without the need for elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the power semiconductor modules are mounted on a closed cooler with a reliable bond, then high thermal conductivity is achieved, but elevated process temperatures cause damage and delamination of the casing
Solution Approach 1:
A mold compound is introduced as an intermediary material that encapsulates the bond layer connecting the power semiconductor module to the base plate. This mold compound protects the bond layer from thermal stress and mechanical damage during the bonding process, enabling reliable high-thermal-conductivity bonding without causing casing damage or delamination.
Solution Approach 2:
The bond layer is encapsulated with mold compound before the bonding process occurs. This pre-protection cushioning prevents thermal shock and mechanical stress from directly affecting the casing during elevated temperature bonding, thereby preventing damage and delamination while still achieving high thermal conductivity.
2Reliability
If screws with O-ring sealing are used to mount power semiconductor modules, then leak-tight seal is achieved, but thermal conductivity is reduced
Solution Approach 1:
The sealing function and thermal bonding function are merged into a single integrated bond layer. The bond layer simultaneously provides leak-tight sealing between the power semiconductor module and base plate while maintaining high thermal conductivity, eliminating the need for separate O-ring sealing and screw mounting.
Solution Approach 2:
The mold compound acts as an intermediary that protects the bond layer, enabling it to perform both sealing and thermal conduction functions effectively. The encapsulation ensures the bond layer maintains its integrity for both sealing and heat transfer without interference from external mechanical fastening elements.
3Ease of manufacture
If the bond layer is exposed, then manufacturing simplicity is maintained, but the risk of coolant leakage increases
Solution Approach 1:
The mold compound forms a protective shell or encapsulation around the bond layer. This shell protects the bond layer from coolant exposure and potential leakage paths, significantly improving leak protection while the encapsulation process remains compatible with standard manufacturing techniques.
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
This design reduces the risk of coolant leakage, enhances thermal cycling capability, and allows for higher operating temperatures while minimizing the risk of delamination and damage, thus improving the reliability and efficiency of power modules.
Implementation Method 1
a bond layer connects the power semiconductor module and the base plate
Data Source
AI summary
A power module includes a power semiconductor module having a semiconductor chip arranged on a substrate. A lead frame is arranged in electrical contact with the semiconductor chip. Abase plate includes cooling structures and micro channels that are connected to an inlet port and an outlet port. A bond layer connects the power semiconductor module and the base plate. A mold compound is arranged on the power semiconductor module, the bond layer and the base plate. The bond layer is encapsulated completely by the power semiconductor module, the base plate and the mold compound and the lead frame is arranged at least partially within the mold compound.