Power Module Sealing Resin Adhesion via Rough Metal Case Surface
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Solution Overview
Problem
In power modules for converters, moisture can adhere between the metal case and the power semiconductor module, compromising insulation and heat conductivity.
Innovation Solution
A power module design featuring a power semiconductor module with conductor plates and a first sealing resin, integrated within a metal case with a heat dissipation unit and a second sealing resin that adheres to a rough surface layer on the metal case's inner surface, enhancing adhesiveness and sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth inner surface is used on the metal case, then manufacturing is easier and surface quality is better, but adhesiveness with the sealing resin is insufficient allowing moisture to adhere
Solution Approach 1:
The rough surface layer is applied only to the specific region on the inner surface of the metal case that contacts the sealing resin, rather than the entire surface. This partial application provides sufficient adhesiveness for sealing while minimizing additional manufacturing complexity and maintaining smooth surfaces in other areas.
Solution Approach 2:
The inner surface of the metal case is given different surface qualities in different regions: a rough surface layer is formed only in the region that contacts the sealing resin to enhance adhesiveness, while other regions maintain their original smooth surfaces for manufacturing efficiency and aesthetic purposes.
2Reliability
If a rough surface layer is formed on the inner surface of the metal case to improve adhesiveness, then sealing force is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of making the entire inner surface rough, only the necessary contact region with the sealing resin is treated with a rough surface layer. This reduces the overall complexity added to the metal case while achieving the required sealing force in the critical area.
Solution Approach 2:
The metal case inner surface is differentiated into two zones: a rough surface layer zone for enhanced sealing adhesion and a smooth surface zone for general structural purposes. This localized differentiation improves sealing without unnecessarily complicating the entire case structure.
3Reliability
If moisture adheres between the metal case and power semiconductor module, then insulation performance deteriorates, but adding sealing structures increases manufacturing complexity
Solution Approach 1:
The rough surface layer is pre-formed on the metal case inner surface before assembly with the power semiconductor module. This preliminary surface treatment ensures that when the sealing resin is applied during assembly, it achieves optimal adhesion and sealing, preventing moisture ingress without requiring complex assembly procedures.
Solution Approach 2:
The sealing enhancement is achieved by treating only the critical contact region between the metal case and sealing resin with a rough surface layer, rather than implementing complex sealing structures throughout the entire assembly. This localized approach maintains insulation performance while simplifying the overall manufacturing process.
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 improved sealing force and adhesiveness between the second sealing resin and the metal case's inner surface enhance the module's insulation and heat dissipation performance, reducing moisture ingress and increasing reliability.
Implementation Method 1
a rough surface layer, for improving adhesiveness with the second sealing resin, at least on a region opposing the side surface of the second sealing resin on the inner surface of the metal case
Implementation Method 2
the second sealing resin fills dents of the rough surface layer
Implementation Method 3
the second sealing resin fills dents of the rough surface layer
Implementation Method 4
a metal case including a heat dissipation unit on an outer side surface thereof
Data Source
AI summary
Sealing force between a metal case and a power semiconductor module is improved. In a power semiconductor module 3, peripheral side surfaces of power semiconductor devices 31U and 31L and conductor plates 33 to 36 are integrated by being covered with a first sealing resin 6. An oxide layer (rough surface layer) 46 is formed on an inner surface of a metal case 40. A fluid resin material is injected into a space S between the oxide layer 46 provided to the metal case 40 and a power semiconductor module 30, and then a second sealing resin 52 is formed. The second sealing resin 52 fills dents of the oxide layer 46, and therefore sealing force improves.