Electrostatic Chuck Joining Layer With Porous Stress Buffering
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Solution Overview
Problem
Existing techniques for joining bodies with different thermal expansion coefficients, such as those described in Patent Documents 1 and 2, face issues with insufficient stress buffering or failure in joining due to varying degrees of brazing filler metal infiltration, leading to potential separation and warpage.
Innovation Solution
A joined body configuration with a metal layer having unfilled holes impregnated with joining materials, allowing for stress buffering through deformation, and ensuring secure joining of ceramic and metal members using inorganic or metal joining materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a porous metallic material is used as an intermediate layer to buffer thermal stress, then the stress buffering ability is improved, but the degree of infiltration of brazing filler metal becomes uncontrollable leading to insufficient joining or reduced stress buffering effect
Solution Approach 1:
The patent divides the intermediate layer into three distinct functional zones: a first impregnated layer near the first member, a second impregnated layer near the second member, and an unfilled hole layer in the middle. This segmentation allows the outer layers to provide reliable joining through brazing filler metal infiltration while the central unfilled layer maintains stress buffering capability, thus resolving the contradiction between joining reliability and stress buffering ability.
Solution Approach 2:
Different regions of the intermediate layer are given different properties: the first and second impregnated layers have high brazing filler metal content for strong joining, while the unfilled hole layer has high porosity for stress buffering. This local differentiation of material properties allows each zone to perform its specific function optimally, solving the contradiction between reliable joining and effective stress buffering.
2Stability of the object's composition
If the joining layer thickness is increased to prevent decrease in thermal stress relaxing ability, then the stress buffering effect is improved, but the cell structure becomes fixed and the stress buffering effect becomes smaller during use
Solution Approach 1:
The patent utilizes a porous metallic material with controlled porosity (50-90%) as the intermediate layer. The porous structure provides both mechanical strength and stress buffering capability. The unfilled hole layer specifically maintains high porosity to enable deformation under thermal stress, preventing the cell structure from becoming fixed while still providing adequate thermal stress relaxing ability.
Solution Approach 2:
By segmenting the intermediate layer into impregnated and unfilled regions, the patent achieves a balance where the overall layer thickness provides thermal stress relaxing ability while the unfilled hole layer maintains adaptability for stress buffering during use through its deformable porous structure.
3Strength
If brazing filler metal infiltration into porous metallic material is increased to ensure joining, then the joining strength is improved, but the stress buffering effect of the porous metallic material becomes smaller
Solution Approach 1:
The patent segments the intermediate layer into first and second impregnated layers for strong joining and an unfilled hole layer for stress buffering. This segmentation ensures that brazing filler metal infiltration is concentrated in the outer layers where joining strength is needed, while the central unfilled layer retains its porous structure for effective stress buffering, thus resolving the contradiction between joining strength and stress buffering effect.
Solution Approach 2:
Different regions of the intermediate layer have different degrees of brazing filler metal infiltration: the impregnated layers have high infiltration for strong joining, while the unfilled hole layer has low infiltration to preserve stress buffering. This local quality differentiation resolves the contradiction by allowing each region to optimize for its specific function.
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 configuration effectively buffers thermal stresses, preventing separation and warpage, and enhances joining integrity, particularly under high-temperature conditions, with a stress buffering effect achieved through a specific void fraction and metal fiber diameter range.
Implementation Method 1
stresses generated as a result of deformation of the first member and the second member can be buffered by the metal layer
Implementation Method 2
the metal layer can deform under a heating or cooling atmosphere during use of the joined body
Implementation Method 3
the metal layer of the joining portion has the unfilled hole layer... as a result of the metal layer being impregnated with the joining materials
Data Source
AI summary
A joined body includes a first member, a second member, and a joining portion disposed therebetween and joining the first member and the second member. The joining portion includes a first joining layer on a side toward the first member and formed of a first joining material, a second joining layer on a side toward the second member and formed of a second joining material, and a metal layer therebetween and having a plurality of holes communicating with one another. The metal layer includes a first-joining-material-impregnated layer on a side toward the first joining layer and in which the plurality of holes are impregnated with the first joining material, a second-joining-material-impregnated layer on a side toward the second joining layer and in which the plurality of holes are impregnated with the second joining material, and an unfilled hole layer therebetween and in which the plurality of holes are void.