Ceramic Substrate With Differential Brazing Layers for Warpage Control
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Solution Overview
Problem
Ceramic substrates used for mounting high-power transistors in electric motors face warpage issues when the heat dissipation plate or circuit plate is made thicker to enhance thermal conductivity, as existing methods do not effectively manage the thickness difference between these components.
Innovation Solution
A ceramic substrate design featuring a flat ceramic base with differential brazing material layers, where the thickness of the brazing material layers is adjusted to match the thickness difference between the heat dissipation plate and the circuit plate, with the thicker plate having a correspondingly thicker brazing material layer to mitigate warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the heat dissipation plate is increased to improve thermal conductivity, then heat dissipation performance is improved, but warpage occurs during manufacturing
Solution Approach 1:
The patent applies asymmetry by making the brazing material layer thickness asymmetric - the first brazing material layer (under the heat dissipation plate) is made thicker than the second brazing material layer (under the circuit plate). This asymmetric thickness distribution compensates for the thermal expansion differences caused by the thick heat dissipation plate, thereby suppressing warpage while maintaining improved heat dissipation performance
Solution Approach 2:
The patent changes the parameter of brazing material layer thickness to resolve the contradiction. By adjusting the thickness of the first brazing material layer to be greater than that of the second brazing material layer, the system compensates for the thermal stress induced by the thick heat dissipation plate, preventing warpage while preserving the enhanced thermal conductivity
2Power
If the thickness of the circuit plate is increased to increase current flow, then electrical performance is improved, but warpage occurs during manufacturing
Solution Approach 1:
The patent applies asymmetry by adjusting the brazing material layer thicknesses differently on each side of the ceramic substrate. When the circuit plate is made thicker, the second brazing material layer can be made thinner relative to the first, creating an asymmetric compensation mechanism that balances thermal expansion forces and suppresses warpage while allowing increased current flow capability
Solution Approach 2:
The patent changes the brazing material layer thickness parameters to compensate for the increased circuit plate thickness. By making the second brazing material layer thinner than the first, the system offsets the thermal stress from the thick circuit plate, preventing warpage while maintaining the improved electrical performance
3Temperature
If the thickness difference between heat dissipation plate and circuit plate is increased, then thermal conductivity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by differentiating the brazing material layer thickness at different locations - the first brazing material layer under the heat dissipation plate is made thicker while the second brazing material layer under the circuit plate is made thinner. This localized thickness variation allows the system to handle large thickness differences between plates without increasing overall manufacturing complexity, as it only requires localized adjustment of brazing material application
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 design effectively suppresses warpage in ceramic substrates even when one of the heat dissipation or circuit plates is thicker, ensuring stable manufacturing and improved thermal conductivity.
Implementation Method 1
a first brazing material layer provided on a first main surface of the insulating base; a second brazing material layer provided on a second main surface of the insulating base; a circuit plate comprising a metal and being fixed through the first brazing material layer to the insulating base; and a heat dissipation plate comprising a metal and being fixed through the second brazing material layer to the insulating base
Data Source
AI summary
A ceramic substrate is provided with a flat plate-shaped insulating base composed of a ceramic, a first brazing material layer provided on a first main surface of the insulating base, second brazing material layer provided on a second main surface of the insulating base, a circuit plate composed of a metal and fixed through the first brazing material layer to the insulating base on a first main surface-side, and a heat dissipation plate composed of a metal and fixed through the second brazing material layer to the insulating base on a second main surface-side. A thickness of one of the heat dissipation plate and the circuit plate is larger than a thickness of the other. When the thickness of the heat dissipation plate is larger than the thickness of the circuit plate, a thickness of the first brazing material layer is larger than a thickness of the second brazing material layer. When the thickness of the circuit plate is larger than the thickness of the heat dissipation plate, the thickness of the second brazing material layer is larger than the thickness of the first brazing material layer.