Brazing Non-Diffusing Ceramics With Aluminum Alloy
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Solution Overview
Problem
Current ceramic joining methods require high temperatures and pressures, leading to high manufacturing costs and the inability to achieve hermetic seals, especially for non-diffusing ceramics like aluminum nitride, alumina, and zirconia, which also limit repair and rework capabilities.
Innovation Solution
A brazing method using a controlled atmosphere and aluminum alloy to join ceramic pieces at lower temperatures, ensuring a hermetic seal without diffusion into the ceramics, allowing for the use of non-diffusing ceramics like aluminum nitride, alumina, and zirconia, and enabling the preservation of material properties and the ability to disassemble for repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If liquid phase sintering is used to join ceramic materials, then strong bonds are achieved, but very high temperatures and pressures are required leading to high manufacturing costs
Solution Approach 1:
A metal interlayer is introduced between the ceramic components to facilitate joining at lower temperatures. The metal interlayer acts as a mediator that bonds to the ceramic surfaces and provides a pathway for joining without requiring the extreme temperatures and pressures of liquid phase sintering, thereby reducing manufacturing costs while maintaining bond strength.
Solution Approach 2:
The joining temperature and pressure parameters are significantly reduced by changing the joining mechanism from direct ceramic-to-ceramic liquid phase sintering to ceramic-to-metal-to-ceramic brazing. This parameter change allows joining to occur at lower temperatures and pressures, reducing the complexity and cost of manufacturing equipment and processes.
2Reliability
If diffusion bonding is used to join ceramic pieces, then hermetic seals are achieved, but significant amounts of time are required and material properties are altered
Solution Approach 1:
The metal interlayer serves as an intermediary that enables hermetic sealing through controlled diffusion and metallurgical bonding at lower temperatures and shorter times compared to direct diffusion bonding of ceramics. The metal layer facilitates rapid diffusion and bond formation without requiring the extended time periods needed for direct ceramic-to-ceramic diffusion bonding.
Solution Approach 2:
The joining temperature and time parameters are optimized by using a metal interlayer, which allows hermetic seals to be achieved at lower temperatures and significantly reduced time compared to traditional diffusion bonding. The metal interlayer enables faster diffusion kinetics and bond formation.
3Strength
If high temperature joining processes are used, then ceramic pieces are joined, but the pieces cannot be disassembled for repair
Solution Approach 1:
The metal interlayer acts as a reversible bonding interface that allows for controlled disassembly. The metallurgical bond between the metal and ceramic can be selectively broken through controlled heating or mechanical means, enabling disassembly for repair while maintaining strong joint strength during normal operation. This intermediary layer provides a reversible bonding mechanism unlike permanent high-temperature ceramic bonds.
4Ease of manufacture
If specialized fixturing and high-temperature ovens are used for ceramic joining, then joining is achieved, but device complexity increases
Solution Approach 1:
The joining temperature and pressure parameters are reduced to levels that can be achieved with simpler, more common equipment. The metal interlayer enables joining at temperatures and pressures that do not require specialized high-temperature ovens and complex fixturing, thereby reducing device complexity while maintaining joining capability.
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 method reduces manufacturing costs by eliminating the need for high-temperature ovens and specialized fixturing, achieves hermetic seals, and allows for the reuse of ceramic components by maintaining their material properties and enabling disassembly for repair.
Implementation Method 1
heating the brazing layer to a temperature of at least 800 C and cooling the brazing layer to a temperature below its melting point
Implementation Method 2
The wetting and flow of the joining material is controlled by the selection of the joining material, the joining temperature, the joining atmosphere
Implementation Method 3
The wetting and flow of the joining material is controlled by the selection of the joining material, the joining temperature, the joining atmosphere
Implementation Method 4
brazing a layer of joining material between the two pieces... under controlled atmosphere
Data Source
AI summary
A method for the joining of ceramic pieces with a hermetically sealed joint comprising brazing a layer of joining material between the two pieces. The wetting and flow of the joining material is controlled by the selection of the joining material, the joining temperature, the joining atmosphere, and other factors. The ceramic pieces may be on a non-diffusable type, such as aluminum nitride, alumina, beryllium oxide, and zirconia, and the pieces may be brazed with an aluminum alloy under controlled atmosphere. The joint material is adapted to later withstand both the environments within a process chamber during substrate processing, and the oxygenated atmosphere which may be seen within the shaft of a heater or electrostatic chuck.