Turbo-molecular pump nickel plating for corrosion resistance
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Solution Overview
Problem
In semiconductor manufacturing processes, chlorine-based or fluorine-based gases used in vacuum chambers can corrode components of turbo-molecular pumps, leading to the release of metal particles containing Fe or Cr, which cause contamination in the vacuum chamber.
Innovation Solution
Applying nickel plating selectively to the gas contacting sections of turbo-molecular pump components on the upstream side of the first rotor blade, excluding abutment surfaces and areas not directly exposed to corrosive gases, to prevent corrosion and metal particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroless nickel plating is applied to components in the vacuum chamber to prevent corrosion, then corrosion resistance is improved, but manufacturing complexity increases due to unclear coating area specifications
Solution Approach 1:
The patent applies electroless nickel plating selectively to specific gas-contacting surfaces of components (suction port, flange, rotor blade upstream side, stator blade upstream side, exhaust port) rather than entire components. This localized coating approach provides corrosion protection where needed while simplifying manufacturing by clearly defining coating areas.
2Reliability
If nickel plating is applied to all component surfaces, then corrosion protection is improved, but metal particle generation increases from unnecessary coating areas
Solution Approach 1:
The patent restricts nickel plating application to only those surfaces that contact corrosive gases during pump operation. By excluding non-gas-contacting surfaces (such as abutment surfaces, downstream sides of blades, and internal fastening surfaces) from plating, the invention prevents corrosion protection where unnecessary while eliminating the source of metal particle contamination in the vacuum chamber.
3Reliability
If abutment surfaces are coated with nickel plating, then corrosion resistance is improved, but fastening reliability deteriorates due to plating peeling from friction
Solution Approach 1:
The patent extracts abutment surfaces from the nickel plating treatment zone. Specifically, the suction port inner face, flange abutment surfaces, and rotor-stator blade abutment surfaces are excluded from plating. This separation removes the source of plating peeling issues while maintaining corrosion protection on gas-exposed surfaces.
4Reliability
If nickel plating is applied to the first rotor blade upstream side, then corrosion resistance is improved, but the blade becomes unbalanced due to added weight
Solution Approach 1:
The patent applies nickel plating only to the upstream side surface of the first rotor blade that contacts corrosive gases, while excluding the downstream side and abutment surfaces. This localized approach provides necessary corrosion protection on the gas-exposed surface while minimizing added mass and maintaining rotor balance.
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
Prevents corrosion of stainless and steel components, thereby suppressing the generation and backflow of metal particles containing Fe or Cr into the vacuum chamber, reducing contamination risks.
Implementation Method 1
Applying nickel plating selectively to the gas contacting sections of turbo-molecular pump components
Data Source
AI summary
A turbo-molecular pump comprises: a case having a suction port and a flange; a rotor assembly housed inside the case, the rotor assembly having a shaft and a rotor integrated with the shaft with a fastening bolt, the rotor having a plurality of rotor blades formed thereon; a plurality of stator blades housed inside the case and arranged to face the rotor blades; and a plurality of spacers stacked along a peripheral surface of the case, the spacer fixing the stator blades. An anti-corrosion treatment is applied to a gas contacting section in a component that is provided on an evacuation upstream side with respect to an evacuation downstream side end of the first rotor blade from the evacuation upstream side and made of an alloy containing Fe or Cr.