Ceramic Carrier Substrate Bonding for High-Temperature Heat Sinks
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Solution Overview
Problem
Existing heat sinks for electrical components, particularly those using metal-ceramic substrates, are limited by the choice of ceramic materials due to bonding processes, preventing the use of materials like Si3N4 that offer high thermal conductivity and insulation, and traditional solder-based bonding methods fail to withstand the high temperatures required for heat sink attachment.
Innovation Solution
A solder-free bonding layer with a high surface resistance, achieved through hot isostatic pressing and an active metal layer, connects the heat sink to ceramic elements like Si3N4, allowing temperatures that do not damage the bond, and enabling the use of materials that were previously unsuitable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder-based bonding is used to attach the heat sink to the ceramic element, then the bonding process can be performed at lower temperatures, but the bond cannot withstand the high temperatures required for heat sink attachment
Solution Approach 1:
The patent removes the solder material from the bonding layer, extracting the problematic component that cannot withstand high temperatures. The bonding layer consists solely of active metal that forms a heat-resistant bond between the heat sink and ceramic element, eliminating the temperature limitation imposed by solder melting points.
Solution Approach 2:
The patent changes the material composition parameter of the bonding layer from solder-based to active metal-only. This parameter change enables the bonding layer to withstand the high temperatures (typically above 400°C) required for heat sink attachment while maintaining bond strength, as active metals form stable intermetallic compounds at these temperatures.
2Adaptability or versatility
If traditional bonding processes are used, then the manufacturing process is simple, but the choice of ceramic materials is limited and high thermal conductivity materials like Si3N4 cannot be utilized
Solution Approach 1:
The patent uses an active metal layer as an intermediary between the heat sink and the ceramic element. This active metal serves as a mediator that can bond to both the heat sink metal and the ceramic material (including Si3N4), enabling the use of high-performance ceramics that would otherwise be incompatible with traditional solder-based bonding processes.
Solution Approach 2:
The bonding layer is formed as a composite structure through the interaction of active metal with the ceramic element surface. The active metal creates a metallurgical bond with the ceramic that is stable at high temperatures, enabling the combination of dissimilar materials (metal heat sink and ceramic insulator) with complementary properties.
3Reliability
If a solder-containing bonding layer is used, then the bonding process is easier to perform, but the surface resistance is insufficient and the bond is damaged at heat sink attachment temperatures
Solution Approach 1:
The patent extracts the solder material from the bonding layer, removing the component that fails at high temperatures. The resulting bonding layer consists only of active metal that forms a thermally stable bond, eliminating the temperature threshold limitation imposed by solder melting and degradation.
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 solution provides a robust, high-surface-resistance bond that withstands heat sink attachment temperatures, enabling the use of high thermal conductivity ceramic materials like Si3N4, enhancing heat dissipation and insulation in electrical components.
Implementation Method 1
the bonding to the ceramic element is achieved via hot isostatic pressing, preferably hot isostatic pressing in which an active metal layer is arranged between the ceramic element and the metal layer to be bonded
Implementation Method 2
a cooling fluid is circulated through this channel to absorb and dissipate heat emanating from the electrical or electronic component
Data Source
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AI summary
The invention relates to a carrier substrate (1) for electrical components (4), comprising: - a heat sink (20), and - a ceramic element (71), wherein the ceramic element (71) is bonded at least in some sections to the heat sink (20), wherein in the finished carrier substrate (1) a bonding layer without solder material is formed between the heat sink (20) and the ceramic element (71), and wherein an adhesion promoter layer of the bonding layer has a sheet resistance greater than 5 ohms/square, preferably greater than 10 ohms/square and particularly preferably greater than 20 ohms/square.