Silicon Balance Spring Fabrication with Internal Wafer Anchors
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Solution Overview
Problem
Existing methods for manufacturing silicon timepiece components face challenges in maintaining attachments to the wafer without impairing functional surfaces and ensuring a clean, immaculate appearance, particularly for components with micro-toothing, and do not allow for decoration or surface treatment on the rear face.
Innovation Solution
A method using SOI wafers with a silicon oxide bonding layer to form internal anchors and bridges, allowing components to be attached to a non-critical inner contour while enabling access to the rear face for decoration and surface treatment, using DRIE and wet etching to release the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If attachments are used to connect components to the wafer during manufacturing, then the components can be held and manipulated easily, but the functional outer surface of the component is impaired by attachment residues
Solution Approach 1:
The patent moves the attachment from the outer peripheral surface (2D plane) to the inner contour area (internal dimension), allowing the component to be held without attaching to the functional outer surface. This dimensional relocation resolves the conflict between ease of handling and surface quality.
Solution Approach 2:
The patent segments the component structure by identifying a specific inner contour area separate from the functional outer surface, allowing independent treatment of attachment and functional areas. This segmentation enables the attachment to be placed in a non-critical area without affecting the functional surface quality.
2Strength
If attachments are placed on the outer contour of the component, then the component can be securely attached to the wafer, but the functional outer surface is compromised and no decoration or surface treatment can be applied
Solution Approach 1:
The attachment is relocated from the outer contour (external dimension) to the inner contour area (internal dimension), freeing the outer surface for decoration and surface treatment while maintaining secure attachment through the internal anchor element and bridge structure.
Solution Approach 2:
The attachment structure is nested within the component's internal geometry, with the anchor element and bridge contained within the component's outer profile. This nesting allows the outer surface to remain fully accessible for aesthetic treatments while the internal structure provides secure attachment.
3Ease of operation
If the component periphery is used for attachment, then the component can be held during manufacturing, but components with micro-toothing lack sufficient free space for strong attachments
Solution Approach 1:
The attachment location is shifted from the outer periphery (where micro-toothing leaves insufficient space) to the inner contour area (which provides adequate space). This dimensional shift resolves the space constraint issue for micro-toothing components while maintaining handling capability.
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
Enables the manufacturing of silicon timepiece components with functional external profiles by maintaining attachments without interfering with the outer surface, allowing for decoration and surface treatment, and ensuring precise, clean finishes.
Implementation Method 1
growing a silicon oxide layer on the surface of the wafer
Implementation Method 2
etching the silicon oxide layer (etching mask) on the face, then the 'device' layer by DRIE
Implementation Method 3
releasing the timepiece component by means of wet etching
Data Source
AI summary
A method for manufacturing a silicon timepiece component (1) with a functional external profile.