Composite Micromechanical Component Fabrication via Silicon Dioxide Buffer
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Solution Overview
Problem
Existing methods for fabricating silicon-metal composite micromechanical components are complex and unsuitable for components with high slenderness ratios, as they often result in delamination due to inner stresses in deposited materials like nickel-phosphorus, and require additional coating steps to improve tribological properties.
Innovation Solution
A method involving a substrate with conductive top and bottom layers separated by an insulating layer, where patterns are etched and coated with silicon dioxide to form cavities, followed by electrodeposition to integrate tribologically superior metal parts within the component, reducing the need for post-fabrication coatings and minimizing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If galvanic growth is used to deposit metal parts in silicon-metal composite micromechanical components, then metal parts can be integrated into the component, but inner stresses in the deposited nickel-phosphorus cause delamination
Solution Approach 1:
A silicon dioxide intermediate layer is introduced between the silicon substrate and the nickel-phosphorus metal deposit. This intermediary layer acts as a stress buffer that prevents delamination by accommodating the inner stresses generated during galvanic growth, while still allowing the metal parts to be successfully integrated into the micromechanical component.
Solution Approach 2:
The invention creates a multi-layer composite structure consisting of silicon substrate, silicon dioxide intermediate layer, and nickel-phosphorus metal parts. This composite approach combines materials with different mechanical properties to achieve both successful metal integration and delamination resistance through the stress-absorbing silicon dioxide layer.
2Ease of manufacture
If photosensitive resins and galvanic growth are used to fabricate silicon-metal composite micromechanical components, then metal parts can be formed, but the method becomes complex to implement for metal parts over several levels
Solution Approach 1:
The silicon dioxide intermediate layer is deposited in advance on the silicon substrate before the galvanic growth process begins. This preliminary action simplifies subsequent metal deposition steps by providing a stable base layer, eliminating the need for complex intermediate steps when forming metal parts at multiple levels.
Solution Approach 2:
The fabrication process is segmented into distinct stages: first depositing the silicon dioxide intermediate layer, then performing galvanic growth for metal parts at different levels. This segmentation allows each step to be optimized independently, reducing overall process complexity while enabling multi-level metal integration.
3Ease of manufacture
If micromachinable material is used for the component structure, then the component can be fabricated, but the tribological properties are insufficient
Solution Approach 1:
The silicon dioxide coating is applied specifically to surfaces that require improved tribological properties, such as contact surfaces and vertical walls, while leaving other areas as micromachinable silicon. This localized treatment enhances friction and wear resistance where needed without compromising the overall fabricability of the component.
Solution Approach 2:
The component becomes a composite structure combining micromachinable silicon with silicon dioxide coating layers. This composite material approach allows the base silicon to provide ease of fabrication while the silicon dioxide surfaces provide superior tribological properties for operational reliability.
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 simplifies the fabrication process, enhances tribological properties by integrating better deposition within the component, and prevents peeling issues with materials like nickel-phosphorus, allowing for precise and reliable micromechanical components with improved geometrical precision and mechanical force transmission.
Implementation Method 1
directionally etching said coating and said intermediate layer so as to limit the presence thereof exclusively at each vertical wall formed in the top layer
Implementation Method 2
performing an electrodeposition by connecting the electrode to the conductive bottom layer of the substrate to form at least one metallic part of the composite component
Data Source
AI summary
The invention relates to a method of fabricating a composite micromechanical component, particularly for timepiece movements, including steps: a) providing a substrate including a horizontal top layer and a horizontal bottom layer made of electrically conductive, micromachinable material, and secured to each other by an electrically insulating, horizontal, intermediate layer; b) etching a pattern in the top layer through to the intermediate layer, thereby forming at least one cavity in the substrate; c) coating the top part of the substrate with an electrically insulating coating; d) directionally etching the coating and the intermediate layer to limit the presence thereof exclusively at each vertical wall; e) performing an electrodeposition by connecting the electrode to the conductive bottom layer of the substrate to form at least one metal part of the component; g) releasing the composite component from the substrate.