Power Module Substrate Recesses for Resin Leak Prevention
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Solution Overview
Problem
Existing power conversion devices face issues with substrate thickness variation and resin leakage during manufacturing, leading to potential substrate surface layer wiring breakage and reduced yield due to strong mold clamping.
Innovation Solution
A power module design featuring R-shaped recesses around the sealing material to absorb thickness variations, preventing resin leakage and allowing for miniaturization and improved yield by using R-shaped mold protrusions during transfer molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strong mold clamping is applied during transfer molding to prevent resin leakage, then sealing quality is improved, but substrate surface layer wiring breakage occurs
Solution Approach 1:
The patent applies preliminary action by forming R-shaped recesses in the substrate surface layer wiring before the transfer molding process. These pre-formed recesses create a stress-absorbing structure that prevents wiring breakage during subsequent mold clamping, allowing strong clamping to be applied without damaging the wiring.
Solution Approach 2:
The R-shaped recesses serve as a cushioning structure that absorbs and distributes the stress from mold clamping. By providing this stress-absorbing feature beforehand, the patent prevents direct transmission of clamping forces to the wiring, thereby preventing breakage while maintaining strong mold clamping for sealing quality.
2Reliability
If substrate thickness is increased to prevent resin leakage, then sealing reliability is improved, but device size increases
Solution Approach 1:
Instead of increasing the overall substrate thickness, the patent applies local quality by creating R-shaped recesses only in specific areas where resin leakage is prone to occur. This localized structural modification provides the necessary sealing reliability without increasing the overall device volume.
Solution Approach 2:
The patent solves the thickness-volume contradiction by transitioning from a one-dimensional thickness increase to a two-dimensional surface feature (R-shaped recesses). This dimensional change allows the substrate to maintain its original thickness while providing enhanced sealing capability through surface-level structural modifications.
3Manufacturing precision
If dummy wiring is added to prevent resin leakage, then sealing quality is improved, but substrate area increases
Solution Approach 1:
The patent changes the geometric parameters of the substrate surface by forming R-shaped recesses with specific dimensions and shapes. These parameter modifications create effective stress distribution and resin flow control without adding extra wiring elements, thereby maintaining sealing quality while preserving substrate area.
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(e)
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, in which 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.