Multilayer Assembly Structure for Low-Temperature Joining and Warpage Control
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Solution Overview
Problem
In existing insulating circuit boards, joining at high temperatures often results in warpage due to thermal expansion differences between the heat sink and the ceramic substrate, as well as between copper and aluminum components, leading to decreased joinability.
Innovation Solution
A multilayer assembly is created using a ceramic substrate, an aluminum plate, an intermediate metal layer, a sintered copper layer, and a metal member, allowing for low-temperature joining through a sintered copper layer, thereby reducing warpage and improving joinability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperature joining is used to join the heat sink to the ceramic substrate, then the joining strength is improved, but warpage occurs due to thermal expansion differences
Solution Approach 1:
The patent introduces an intermediate layer structure consisting of a first aluminum plate, first intermediate metal layer, and first sintered copper layer between the heat sink and ceramic substrate. This intermediate structure acts as a mediator that reduces thermal expansion differences and enables low-temperature joining while maintaining connection strength, thereby preventing warpage during the joining process.
Solution Approach 2:
The patent changes the joining temperature parameter from high temperature to low temperature by introducing the intermediate layer structure. This parameter change allows the joining process to be performed at lower temperatures, preventing thermal expansion-induced warpage while still achieving adequate joining strength through the specialized intermediate layer composition.
2Strength
If high temperature joining is used to join copper plates to aluminum plates, then the joining strength is improved, but warpage occurs due to thermal expansion differences
Solution Approach 1:
The patent introduces an intermediate layer structure consisting of a first aluminum plate, first intermediate metal layer, and first sintered copper layer between the heat sink and ceramic substrate. This intermediate structure acts as a mediator that reduces thermal expansion differences and enables low-temperature joining while maintaining connection strength, thereby preventing warpage during the joining process.
Solution Approach 2:
The patent changes the joining temperature parameter from high temperature to low temperature by introducing the intermediate layer structure. This parameter change allows the joining process to be performed at lower temperatures, preventing thermal expansion-induced warpage while still achieving adequate joining strength through the specialized intermediate layer composition.
3Shape
If low temperature joining is used to join the heat sink to the ceramic substrate, then warpage is suppressed, but the joining strength may be reduced
Solution Approach 1:
The patent employs a composite intermediate layer structure comprising a first aluminum plate, first intermediate metal layer, and first sintered copper layer. This composite material structure enables low-temperature joining while maintaining adequate strength by combining materials with complementary properties that facilitate bonding at lower temperatures without sacrificing mechanical integrity.
Solution Approach 2:
The intermediate layer structure serves as a mediator that enables low-temperature joining to achieve both warpage suppression and adequate joining strength simultaneously, resolving the contradiction between temperature reduction and strength maintenance.
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
The proposed solution effectively suppresses warpage and enhances joinability by performing the joining process at a low temperature, ensuring reliable connections between components in insulating circuit boards.
Implementation Method 1
a first sintered copper layer which is joined to a surface of the first intermediate metal layer opposite to the first aluminum plate
Data Source
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Figure 6~7
AI summary
Joining is made at a low temperature and warpage is suppressed in the formation of a multilayer assembly, such as joining of a heat sink to an insulating circuit board. A multilayer assembly including: a ceramic substrate; a first aluminum plate which is joined to one surface of the ceramic substrate and contains aluminum or an aluminum alloy; a first intermediate metal layer which is joined to a surface of the first aluminum plate opposite to the ceramic substrate and contains any of copper, nickel, silver, or gold; a first sintered copper layer which is joined to a surface of the first intermediate metal layer opposite to the first aluminum plate; and a first metal member which is joined to a surface of the first sintered copper layer opposite to the first intermediate metal layer and contains any of aluminum, an aluminum alloy, copper, or a copper alloy.