Ceramic Joint Brazing With Nickel-Phosphorous for High-Temperature Seals
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Solution Overview
Problem
Current methods for joining ceramic objects in semiconductor processing equipment face challenges such as limited temperature resistance, non-uniformity, and high manufacturing costs due to the use of liquid phase sintering and high contact pressures, which restrict the ability to withstand temperatures above 700 C and result in costly and complex manufacturing processes.
Innovation Solution
A method involving the application of titanium and nickel-phosphorous layers on ceramic pieces, followed by assembly and heating in a vacuum to create a hermetic seal, which eliminates the need for liquid phase sintering and high contact pressures, allowing the joined ceramic pieces to withstand higher temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid phase sintering and high contact pressures are used to join ceramic pieces, then the joined ceramic pieces can withstand high temperatures, but the manufacturing process becomes complex and costly requiring specialized high-temperature ovens and presses
Solution Approach 1:
The patent changes the joining temperature parameter from traditional high-temperature liquid phase sintering (above 1700°C) to a lower temperature range (900-1100°C) using a nickel-phosphorous braze alloy. This parameter change enables the use of simpler equipment without specialized high-temperature ovens and presses, while still achieving hermetic seals with vacuum leak rates below 1×10^-9 sccm He/sec
Solution Approach 2:
The patent uses a composite joining approach by applying multiple layers (titanium layer followed by nickel-phosphorous layer) on ceramic surfaces. This composite material system provides both mechanical bonding and hermetic sealing properties at lower temperatures, eliminating the need for complex single-step high-temperature sintering processes
2Strength
If high contact pressures are applied during sintering to join ceramic components, then the joint strength increases, but the shaft walls require thicker cross-sectional thickness which increases heat flow and reduces thermal efficiency
Solution Approach 1:
The patent replaces the mechanical high-contact-pressure sintering system with a chemical bonding system using nickel-phosphorous braze alloy. The joining process uses minimal contact pressure (less than 500 psi) compared to traditional sintering (thousands of psi), as the chemical bonding mechanism provides sufficient joint strength without requiring thick shaft walls to support compressive forces
Solution Approach 2:
The patent changes the pressure parameter from high compressive forces (thousands of psi) in traditional sintering to low contact pressure (less than 500 psi) in the braze joining process. This parameter change allows the use of thinner shaft walls that maintain both joint strength and thermal efficiency by reducing heat flow path length
3Ease of manufacture
If traditional brazing materials like aluminum are used to join ceramic pieces, then the joining process is simpler, but the equipment cannot withstand temperatures above 700°C due to the solidus temperature limit of the brazing material
Solution Approach 1:
The patent uses a composite braze alloy system consisting of nickel and phosphorous (with phosphorous content of 3-13 weight percent). This composite material combines the benefits of simple brazing processes with high-temperature capability, as the nickel-phosphorous eutectic system maintains structural integrity at temperatures above 700°C while still enabling straightforward joining operations
Solution Approach 2:
The patent changes the compositional parameter of the brazing material from aluminum-based (with solidus temperature around 700°C) to nickel-phosphorous-based (with eutectic temperature around 900-1100°C). This compositional parameter change raises the maximum operating temperature limit while maintaining the simplicity of the brazing process
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 achieves a hermetic seal with a vacuum leak rate of <1×10E−9 sccm He/sec, enabling the use of ceramic assemblies in high-temperature semiconductor processing environments while reducing manufacturing complexity and cost by eliminating the need for specialized high-temperature ovens and presses.
Implementation Method 1
heating the nickel-phosphorous braze layer to a temperature above its solidus temperature in vacuum, melting the filler material
Implementation Method 2
heating the nickel-phosphorous braze layer to a temperature above its solidus temperature in vacuum
Data Source
AI summary
A method for the joining of ceramic pieces includes applying a layer of titanium on a first ceramic piece and applying a layer of titanium on a second ceramic piece; applying a layer of nickel on each of the layers of titanium on the first ceramic piece and the second ceramic piece; applying a layer of nickel phosphorous to each of the layers of nickel on the first ceramic piece and the second ceramic piece; assembling the first ceramic piece and the second ceramic piece with the layers of titanium, nickel, and nickel phosphorous therebetween; pressing the layer of nickel phosphorous of the first ceramic piece against the layer of nickel phosphorous of the second ceramic piece; heating the first ceramic piece and the second ceramic piece to a joining temperature in a vacuum; and cooling the first ceramic piece and the second ceramic piece. A hermetic seal is formed between the first ceramic piece and the second ceramic piece.