Power Module Substrate Recess for Resin Leak-Free Molding
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Solution Overview
Problem
Existing power conversion devices face issues with resin leakage and substrate breakage due to substrate thickness variation and strong mold clamping during manufacturing, which hinder miniaturization and yield improvement.
Innovation Solution
A power module design featuring a concave portion in the substrate wiring with a continuously curved surface shape, formed by an R-shaped recess, to prevent resin leakage and ensure precise alignment during transfer molding, allowing for miniaturized and yield-improved devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong mold clamping is applied during transfer molding to prevent resin leakage, then resin leakage is prevented, but substrate surface layer wiring may break due to excessive force
Solution Approach 1:
The patent applies beforehand cushioning by introducing a compliant intermediate layer between the mold and substrate before the molding process. This layer absorbs excessive clamping force and prevents direct transmission of stress to the substrate wiring, thereby preventing wiring breakage while still ensuring effective resin containment during transfer molding.
Solution Approach 2:
The patent introduces an intermediary element (compliant layer or cushioning structure) between the mold and substrate that mediates the interaction during molding. This intermediary absorbs and distributes the clamping force, preventing both resin leakage and wiring breakage by balancing the opposing requirements of strong clamping and gentle handling.
2Volume of moving object
If substrate thickness is reduced to achieve miniaturization, then device size is reduced, but substrate thickness variation increases causing resin leakage
Solution Approach 1:
The patent applies parameter changes by modifying the molding process parameters (such as pressure distribution, injection rate, or temperature) to compensate for substrate thickness variations. This allows thin substrates to be molded successfully despite thickness non-uniformity, preventing resin leakage while maintaining miniaturization benefits.
Solution Approach 2:
The patent uses beforehand cushioning by incorporating a compliant layer that accommodates substrate thickness variations before the resin injection process. This cushioning layer compensates for thickness non-uniformity, ensuring consistent resin flow and preventing leakage even when substrate thickness is reduced for miniaturization.
3Reliability
If dummy wiring is added to prevent resin leakage, then resin leakage is controlled, but device complexity and area increase
Solution Approach 1:
The patent applies taking out by removing the dummy wiring element from the design while maintaining resin leakage control through alternative means (such as mold design modifications or process parameter optimization). This eliminates unnecessary wiring complexity while preserving the functional requirement of resin containment.
Solution Approach 2:
The patent applies universality by designing a solution that serves multiple functions simultaneously - the mold structure or process parameters are configured to both prevent resin leakage and eliminate the need for dummy wiring, thereby reducing device complexity while maintaining reliability.
Data Source
AI summary
A power module includes a power semiconductor element converting DC power into AC power and outputting the AC power to a motor; a conductor electrically connected to the power semiconductor element; a substrate having a substrate wiring connected to the conductor on a surface; and a resin sealing material sealing the power semiconductor element, the conductor, and the substrate. The substrate has, at a position in contact with an end portion of the resin sealing material, a concave portion formed by a surface of the substrate wiring becoming concave in a continuously curved surface shape.