Low-Profile Power Module Creepage Design for 6 mm Isolation
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Solution Overview
Problem
Existing power modules fail to effectively address the technical problem of existing power modules fail to address the technical problem of existing power modules fail to effectively address the technical problem of existing power modules fail to address the technical problem of existing power modules fail to address the technical problem of existing power modules fail to effectively reduce package height to 6mm or less without compromising creepage distance and electrical isolation in baseplateless power modules.
Innovation Solution
A baseplateless power module design with a lidless electrically insulative enclosure and a thinner electrically insulative coating, utilizing a jetting process for conformal coating and incorporating protruding ridges to enhance creepage distance, maintains electrical isolation and thermal expansion accommodation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the package height is decreased to meet spatial requirements (e.g., to 6mm or less), then the power module can be integrated into applications with limited space, but the creepage distance between terminals decreases
Solution Approach 1:
The patent extends the creepage pathway from a two-dimensional surface measurement to a three-dimensional path that travels through the interior volume of the enclosure. By routing the creepage path through the depth of the housing rather than along the top surface, the effective creepage distance is increased without increasing the horizontal footprint or package height. This dimensional transition allows the module to maintain adequate creepage clearance in a compact form factor.
2Length of moving object
If the package height is decreased to meet spatial requirements, then the power module fits in smaller spaces, but the volume available to accommodate thermal expansion of the electrically insulative coating decreases
Solution Approach 1:
The patent utilizes the vertical dimension and internal volume of the enclosure to provide thermal expansion accommodation. Rather than requiring additional horizontal space, the design allows the insulative coating to expand into the available volume within the enclosure boundaries. The enclosure is designed with sufficient internal volume to absorb the thermal expansion of the coating material while maintaining a compact external package height.
3Reliability
If the thickness of the electrically insulative coating is increased to ensure sufficient electrical isolation, then the electrical isolation between substrate metallization and semiconductor dies is improved, but the package height increases
Solution Approach 1:
The patent applies the electrically insulative coating selectively to specific areas where electrical isolation is required, rather than uniformly throughout the entire module. The coating is applied to the substrate metallization and semiconductor dies in regions where electrical isolation is critical, while minimizing coating thickness in areas where it is less critical. This localized application maintains adequate electrical isolation while reducing the overall package height.
4Reliability
If a housing material with high comparative tracking index (CTI) is used to decrease required creepage distance, then the creepage distance requirement is reduced, but the material cost increases
Solution Approach 1:
The patent uses geometric design of the enclosure to extend the creepage path through three-dimensional space rather than relying solely on material properties. By designing the enclosure geometry to create a longer creepage pathway that travels through the interior volume, the required CTI of the housing material can be reduced. This allows the use of more cost-effective materials while still meeting creepage distance requirements through intelligent structural design.
Data Source
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AI summary
A power module includes a substrate, a plurality of power semiconductor dies, an electrically insulative enclosure, and an electrical interface for the power semiconductor dies. The substrate includes a first metallized side and a second metallized side separated from one another by an electrically insulative body. The plurality of power semiconductor dies is attached to the first metallized side of the substrate. The electrical interface is accessible outside of the electrically insulative enclosure. An electrically insulative coating is applied to at least part of the first metallized side of the substrate, at least part of the power semiconductor dies, and at least part of the electrical interface. A combined height of the lidless electrically insulative enclosure and the substrate is 6mm or less. The power module may also include a lid or may be lidless.