Insulated Heat Dissipation Substrate Curved Bonding End
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Solution Overview
Problem
The challenge is to enhance the durability of insulated heat dissipation substrates for power semiconductor modules under cooling/heating cycles, as thicker copper plates increase thermal stress and lead to cracking due to thermal expansion differences between copper and ceramic substrates, which existing technologies fail to adequately prevent.
Innovation Solution
The solution involves smoothing the bonding end between the conductor layer and the ceramic substrate, with specific side surface shapes and elevation angles to reduce thermal stress, and expanding the mounting area, thereby improving durability and allowing for thicker copper plates for better heat dissipation and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the copper plate is increased to improve heat dissipation and enable miniaturization, then heat dissipating properties are improved, but thermal stress at the bonding interface increases due to thermal expansion difference between copper and ceramic substrate, causing cracking in the ceramic substrate
Solution Approach 1:
The bonding end of the conductor layer is formed with a curved surface instead of a sharp edge, creating a smooth transition zone between the conductor layer and ceramic substrate. This curvature eliminates stress concentration points and distributes thermal stress evenly, preventing cracking in the ceramic substrate while allowing increased copper plate thickness for improved heat dissipation
2Loss of energy
If the thickness of the copper plate is increased for better heat dissipation, then heat conductivity is improved, but the thermal stress generated at the bonding interface increases, leading to cracking in the ceramic substrate
Solution Approach 1:
The curved surface at the bonding end distributes thermal stress uniformly across the bonding interface, preventing stress concentration that would lead to cracking. This allows the use of thicker copper plates with improved heat conductivity while maintaining bonding interface strength
3Ease of manufacture
If a sharp bonding end is used between conductor layer and ceramic substrate, then manufacturing is simpler, but thermal stress concentration occurs leading to cracking under cooling/heating cycles
Solution Approach 1:
The bonding end is formed with a curved surface through controlled etching or machining, creating a smooth transition that eliminates sharp edges. This curvature prevents stress concentration during thermal cycling while maintaining manufacturing feasibility through standardized processing steps
4Productivity
If the copper plate thickness is increased for miniaturization and heat dissipation, then power density is improved, but residual thermal stress and repeated thermal stress cause cracking in the ceramic substrate
Solution Approach 1:
The curved bonding end surface distributes both residual thermal stress from manufacturing and repeated thermal stress from operation evenly across the bonding interface. This prevents cracking in the ceramic substrate, enabling increased copper plate thickness for improved power density and miniaturization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances the durability of the insulated heat dissipation substrate under cooling/heating cycles, enabling increased copper plate thickness for improved heat dissipation and miniaturization of power semiconductor modules while preventing cracking.
Implementation Method 1
a thermal stress generated at a bonding interface between the copper plate and the ceramic substrate is increased due to a thermal expansion difference between the copper and the ceramic
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; and a side surface 1 connecting the upper surface with the lower surface; the ceramic substrate includes: a lowest portion; a side surface 2 connecting the lowest portion with the side surface 1 of the conductor layer; and a bonding surface at a position higher than the lowest portion, the bonding surface being bonded to the lower surface of the conductor layer; an absolute value (|α−β|) is 20° or less on average; and the side surface 1 has a receding portion from an end of the upper surface in the normal direction relative to the tangential line of the contour of the conductor layer as viewed in plane.