Insulated Heat Dissipation Substrate with Rounded Conductor Edges
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Solution Overview
Problem
Existing insulated heat dissipation substrates face challenges in miniaturization and electric discharge suppression, as they require a balance between maintaining electrical insulating properties and increasing semiconductor chip mounting area, with previous solutions resulting in reduced bonding areas due to corner chamfering which does not effectively address both requirements.
Innovation Solution
The substrate features a conductor layer bonded to a ceramic substrate with a cross-sectional shape where the upper surface tip recedes from the lower surface, and the side surface has an inwardly recessed curve, with a rounded connection portion between the upper and side surfaces, allowing for a larger bonding area while maintaining electrical insulation, even with a smaller curvature radius than previous standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the upper surface outer peripheral corner portion of each metal circuit board is chamfered by an arc shape having a curvature radius of 0.05 mm or more, then electrical insulating properties between adjacent metal circuit boards are improved, but the area for bonding the semiconductor chip is reduced
Solution Approach 1:
The invention applies different geometric characteristics to different parts of the conductor layer: the connection portion between upper and side surfaces has a rounded shape with small curvature radius (0.01-5 μm) for electrical insulation, while the main bonding area maintains a flat surface for optimal chip bonding. This local differentiation resolves the contradiction by providing both insulating properties and bonding area.
Solution Approach 2:
The invention transitions from a two-dimensional planar chamfering approach to a three-dimensional multi-stage geometric structure with rounded connection portions and inwardly recessed side surfaces. This dimensional change allows the bonding area to extend closer to adjacent conductor layers while maintaining electrical insulation through the rounded corners, effectively resolving the area-insulation contradiction.
2Volume of moving object
If the distance between adjacent metal circuit boards is reduced to achieve miniaturization, then the power semiconductor module size is reduced, but electric discharge between the metal circuit boards occurs
Solution Approach 1:
The invention applies spheroidality by rounding the connection portions between the upper surface and side surfaces of conductor layers with a small curvature radius (0.01-5 μm). This rounded geometry prevents electric field concentration at sharp corners, thereby suppressing electric discharge even when the distance between adjacent conductor layers is reduced for miniaturization.
Solution Approach 2:
The invention changes the geometric parameters of the conductor layer edges from sharp corners or large-radius arcs to small-radius rounded portions. This parameter change in the curvature radius (0.01-5 μm) effectively suppresses electric discharge while allowing reduced spacing between conductor layers for module miniaturization.
3Reliability
If the curvature radius of the upper surface outer peripheral corner portion is increased to suppress electric discharge, then electrical insulation is improved, but the dead area increases and bonding area is reduced
Solution Approach 1:
The invention applies local quality by using a small curvature radius (0.01-5 μm) specifically at the connection portions between upper and side surfaces where electric field concentration occurs, while maintaining a flat upper surface for bonding. This localized rounding provides electrical insulation without creating large dead areas, resolving the contradiction between insulation and bonding area.
Solution Approach 2:
The invention applies partial action by rounding only the critical connection portions at the edges of conductor layers rather than the entire surface. This selective rounding with small curvature radius (0.01-5 μm) provides sufficient electrical insulation while minimizing the impact on bonding area, unlike comprehensive chamfering approaches.
Data Source
AI summary
An insulated heat dissipation substrate including: a ceramic substrate; and a conductor layer bonded onto at least one of main surfaces of the ceramic substrate, wherein the conductor layer includes an upper surface, a lower surface bonded to the ceramic substrate, and a side surface connecting the upper surface with the lower surface wherein, a tip of the upper surface recedes in the normal direction of the conductor layer from a tip of the lower surface, the side surface has a contour having an inwardly recessed curve line and having a portion receding in the normal direction of the conductor layer from the tip of the upper surface, and a connection portion between the upper surface and the side surface has a rounded shape such that a maximum radius R of a circle is 0.1 μm≤R≤5 μm on average.