Semiconductor Module Housing With High-CTI Layers for Creepage Isolation
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Solution Overview
Problem
Power semiconductor modules face issues with short-circuits due to insufficient creepage distances between terminal elements with different electrical potentials, which can lead to operational failures or destruction, and existing solutions are costly or difficult to produce while maintaining required electrical isolation.
Innovation Solution
A housing design featuring a first layer with openings and a second layer of higher comparative tracking index material, where the second layer partly covers the first layer, including gaps sealed by the second layer, to extend creepage distances while maintaining low production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If terminal elements with different electrical potentials are arranged close to each other, then the housing size is reduced, but the creepage distance becomes shorter than the minimal required distance causing short-circuits
Solution Approach 1:
A casting compound with high comparative tracking index (CTI) is introduced as an intermediary material between terminal elements with different electrical potentials. This casting compound fills the housing and provides enhanced surface insulation, ensuring that the creepage distance along the surface meets or exceeds the minimal required distance while allowing compact arrangement of terminal elements.
2Reliability
If a housing design with extended creepage distances is implemented, then electrical isolation is improved, but production costs and manufacturing complexity increase
Solution Approach 1:
The solution changes the material parameter (comparative tracking index) of the housing or casting compound to achieve higher surface insulation properties. By selecting materials with higher CTI values, the creepage distance requirement is effectively increased without physically extending the housing dimensions, thereby maintaining compact size while improving electrical isolation and keeping manufacturing relatively simple.
Data Source
AI summary
A housing for a power semiconductor module arrangement includes sidewalls and a top. The top includes a first layer of a first material having a plurality of openings, and a second layer of a second material that is different from the first material. The second material has a comparative tracking index (CTI) that is higher than a comparative tracking index of the first material. The second layer partly covers at least one of a bottom surface of the first layer and a top surface of the first layer, and/or the first layer includes at least one gap sealed by a section of the second layer such that the second layer forms at least one section of the housing.