Silicon Balance Wheel Metal Insert via Blind Cavity
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Solution Overview
Problem
Current methods for producing silicon parts with metal inserts for watchmaking, such as balance wheels, are complex, costly, and prone to embrittlement, with difficulties in precise etching and metal pollution, especially when using Deep Reactive Ion Etching (DRIE), and often require additional assembly or separation steps.
Innovation Solution
A method involving prior structuring of a silicon substrate to form a blind cavity, which is then filled with metal or a metal alloy, eliminating the need for intermediate parts and assembly steps, and allowing for direct integration of metal parts within the silicon substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If metal parts are added to silicon parts by mechanical insertion or in-situ creation by galvanic means, then the inertia/mass ratio is improved, but the manufacturing complexity and cost increase with additional assembly or separation steps
Solution Approach 1:
The patent merges the silicon substrate and metal insert into a single integrated component. The blind cavity is formed directly in the silicon substrate, and metal is deposited in-situ to fill the cavity, eliminating the need for separate assembly steps. This integration achieves the desired inertia/mass ratio while reducing manufacturing complexity.
Solution Approach 2:
The patent performs preliminary structuring of the silicon substrate to create the blind cavity before metal deposition. This preliminary action prepares the substrate for direct metal filling, eliminating the need for subsequent assembly operations and reducing overall manufacturing complexity.
2Ease of manufacture
If a blind cavity is formed in the silicon substrate and filled with metal by galvanic means, then the manufacturing process is simplified, but the presence of metal pollutes the engraving machine and prevents future silicon oxidation operations
Solution Approach 1:
The patent applies local quality by creating a blind cavity with specific geometric characteristics (depth-to-section ratio between 10^-3 and 10^1) that allows metal filling while limiting metal spread. The cavity's localized structure confines the metal to a specific region, preventing pollution of the engraving machine and preserving oxidation capabilities in other areas of the silicon substrate.
Solution Approach 2:
The blind cavity acts as an intermediary structure that enables metal insertion without direct contact between metal and the silicon surface. The cavity walls provide a barrier that prevents metal from polluting the engraving machine and allows future oxidation operations to proceed on the silicon surface without interference from the metal insert.
3Manufacturing precision
If the silicon part is separated from its support after galvanic deposition, then the metal filling is achieved, but the parts become embrittled
Solution Approach 1:
The patent merges the metal filling process with the silicon substrate structure by forming the blind cavity directly in the substrate and filling it in-situ. This eliminates the need for separation from a support structure, thereby avoiding embrittlement while maintaining precise metal filling through controlled galvanic deposition.
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
This method simplifies the manufacturing process, reduces costs, and avoids the risks of embrittlement and pollution, while enabling precise control over the metal insert's placement and shape, enhancing the inertia/mass ratio of watch components like balance wheels.
Implementation Method 1
filling of said cavity with a metal or a metal alloy
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3~5
AI summary
The method involves preliminary structuring of a silicon substrate such that the substrate preliminary possesses a form of a timepiece, where the substrate comprises monolithic silicon block. A blind cavity is formed in the structured silicon substrate, and is filled with a metal/metal alloy (7). A conductive bottom of the cavity is formed, where the bottom is formed by the silicon substrate and by a porous silicon layer. Walls of the cavity are covered by an insulating material layer.