Micro-Mechanical Watch Parts DRIE Process Vertical Flanks
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Solution Overview
Problem
Existing micro-mechanical part manufacturing processes, such as deep reactive ion etching (DRIE), often result in parts with non-vertical sides, leading to uncontrolled contact surfaces and increased risk of breakage or premature wear, especially in precise mechanisms like watch movements.
Innovation Solution
A continuous deep reactive ion etching process with adjusted parameters to produce micro-mechanical parts with optimized lateral flanks, including essentially vertical and inclined sides, allowing for controlled contact surfaces and improved precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deep reactive ion etching (DRIE) is used to manufacture micro-mechanical parts, then vertical or almost vertical sides can be obtained, but the sides often have inclination with respect to the vertical making them less suitable for precise mechanisms
Solution Approach 1:
The patent segments the etching process into multiple distinct steps: a first etching step to create vertical sides, and a second etching step to create inclined sides. This segmentation allows each step to be optimized independently, with the first step achieving verticality and the second step creating the desired inclination angles for proper contact surface control in precise mechanisms.
Solution Approach 2:
The patent employs periodic action by alternating between etching cycles and passivation cycles within each etching step. The passivation layer is deposited periodically to protect lateral surfaces during etching, then removed periodically to allow continued etching. This periodic deposition and removal enables precise control over the etching profile and final side inclination.
2Ease of manufacture
If sides are inclined in parallel (Figure 1), then the side surfaces of contacting parts are uncertain or uncontrolled
Solution Approach 1:
The patent introduces dynamics by making the second etching step adjustable. The inclination angle of the sides created in the second step can be varied by modifying etching parameters such as gas flow rates, pressure, or power. This dynamic adjustment capability allows optimization of contact surface geometry for different mechanical requirements while maintaining manufacturing simplicity through a single integrated process.
3Manufacturing precision
If sides are inclined in opposite direction (Figure 2), then contact surfaces are very small leading to large pressures and risk of breakage
Solution Approach 1:
The patent applies parameter changes by systematically varying etching conditions during the second etching step to achieve optimal side inclination angles. By adjusting parameters such as etching time, gas composition, pressure, or power, the process creates inclined sides that maximize contact surface area between mating parts. This increased contact area distributes mechanical loads more evenly, reducing peak pressures and enhancing resistance to breakage and wear.
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 process ensures better control over contact surfaces and optimized performance in mechanical timepieces by achieving desired profiles with adjusted etching parameters, reducing the risk of breakage and wear.
Implementation Method 1
The basic DRIE process is a plasma etching process which is time multiplexed and consists of two different cycles
Implementation Method 2
ions produced by a plasma are used (for example the ionized gas SF 6 for the etching of silicon)
Implementation Method 3
this plasma gas is replaced by another gas (for example C 4 F 8 ) which results in the deposition of a passivation layer of a material similar to Teflon on all the surfaces of the substrate
Data Source
Figure 1~3
Figure 4~5
AI summary
The present invention relates to a method for manufacturing a micromechanical part, in particular a mechanical watch part, by etching from a substrate. The method comprises at least a first step performed by deep reactive ion etching (DRIE) with parameters adjusted to produce essentially vertical flanks, and a second step performed by deep reactive ion etching (DRIE) with parameters adjusted to produce flanks inclined at a predetermined angle to the vertical. The first and second steps are performed continuously, without stopping the etching process. Furthermore, the present invention also relates to a micromechanical part, in particular a mechanical watch part, manufactured using this method, having a predetermined lateral flank profile.