Metal-Ceramic Bonding Using Controlled Pressing and Active Solder
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Solution Overview
Problem
The challenge lies in creating stable and durable ceramic-metal connections, particularly for high-performance ceramics that undergo thermal cycling, as existing methods face issues with mechanical stress and quality due to differing thermal expansion coefficients and the complexity of vacuum furnaces.
Innovation Solution
A method involving controlled arrangement and pressing of metal and ceramic parts using a stamp before solder softening, followed by resistance heating with controlled current and pressure, ensuring precise positioning and reduced mechanical stress through a sufficient solder layer, allowing for higher adhesive strengths and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum furnaces are used for producing ceramic-metal connections, then connection quality can be improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the essential requirement for oxide removal from the complex vacuum furnace environment and implements it through a simplified active soldering process that operates in ambient atmosphere. The active solder components (aluminum, titanium, or their alloys) chemically react with and remove oxides from the ceramic and metal surfaces, eliminating the need for vacuum conditions while maintaining connection quality.
Solution Approach 2:
The active solder acts as an intermediary substance between the ceramic and metal components. It contains reactive elements that chemically interact with oxide layers on both surfaces, creating a metallurgical bond without requiring vacuum equipment. The solder layer mediates the interface, enabling reliable connections in ambient conditions.
2Adaptability or versatility
If thermal cycling is applied to ceramic-metal connections, then functional performance is improved, but mechanical stress increases due to different thermal expansion coefficients
Solution Approach 1:
The patent changes the chemical composition parameters of the solder layer by using active solder components (aluminum, titanium, or their alloys) that form intermetallic compounds with the ceramic and metal. This compositional change creates a gradient structure that accommodates thermal expansion differences, allowing the connection to withstand thermal cycling without failure.
Solution Approach 2:
The connection structure becomes a composite material system consisting of ceramic, active solder, and metal layers. The active solder layer, being a composite of reactive metals and their intermetallic compounds, provides a transition zone that bridges the thermal expansion mismatch between ceramic and metal, enabling the assembly to survive thermal cycling.
3Strength
If active solder components are used to remove oxides, then adhesive strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The active solder performs self-service by automatically removing oxides from the ceramic and metal surfaces through chemical reaction during the soldering process itself. The reactive components (aluminum, titanium) in the solder react with oxide layers, reducing them in situ without requiring separate surface preparation steps or high-precision manufacturing. The solder 'self-cleans' the surfaces as it bonds them.
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 results in significantly improved adhesive strengths and reproducibility of ceramic-metal connections, withstanding high temperatures and thermal cycling without failure, and can be applied in various applications including electrotechnical purposes without the need for vacuum furnaces.
Implementation Method 1
pressing the metal-ceramic parts against each other with a stamp before the solder has substantially softened
Implementation Method 2
resistance heating with controlled current and pressure
Implementation Method 3
when the solder has softened
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
The invention relates to a process for producing a metal-ceramic compound which is repeatedly thermally cycled during use, in which metal and ceramic are soldered together over an area. Here, the metal and ceramic are arranged against one another in a controlled manner, preferably a displacement-controlled manner.