Galvanoplasty Mold with Insulating Intermediate Layer
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Solution Overview
Problem
Existing methods for fabricating micromechanical parts with high slenderness ratios, such as coaxial escape wheels, face delamination issues due to internal stresses in nickel-phosphorus materials during electrolytic deposition in LIGA techniques.
Innovation Solution
A method involving a substrate with electrically conductive top and bottom layers secured by an insulating intermediate layer, where patterns and recesses are etched to create cavities and recesses with insulating walls, allowing directional etching and electrolytic deposition to avoid delamination, using silicon-based materials for improved adhesion and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LIGA techniques are used to fabricate micromechanical parts with high slenderness ratio, then geometrical precision is improved, but delamination occurs due to internal stresses in nickel-phosphorus material during electrolytic deposition
Solution Approach 1:
The substrate is divided into multiple conductive layers (first conductive layer, second conductive layer) separated by an insulating intermediate layer. This segmentation allows independent electrical connection and stress management for each layer, preventing delamination during electrolytic deposition while maintaining high geometrical precision through controlled etching patterns in each layer.
Solution Approach 2:
An insulating intermediate layer is introduced between the first and second conductive layers. This intermediary layer electrically isolates the layers while mechanically bonding them together, preventing stress-induced delamination during the galvanoplasty process while allowing precise control of the cavity geometry through selective etching.
2Device complexity
If conventional machining is used to fabricate micromechanical parts, then device complexity is reduced, but manufacturing precision deteriorates compared to LIGA techniques
Solution Approach 1:
The fabrication process is segmented into distinct etching steps for the first and second conductive layers, with the insulating intermediate layer providing clear separation. This allows conventional machining techniques to be applied to each layer independently while achieving LIGA-level precision through the cumulative effect of controlled etching patterns and selective removal of material.
3Adaptability or versatility
If multiple levels are fabricated in a single substrate layer, then device integration is improved, but control over independent thickness and positioning deteriorates
Solution Approach 1:
Multiple conductive layers are stacked vertically with an insulating intermediate layer between them, allowing each layer to be independently patterned and etched. This enables precise control of thickness and positioning for each level while maintaining high device integration, as each layer can be optimized independently through selective etching processes.
Solution Approach 2:
The invention transitions from planar multi-level fabrication to vertical stacking of conductive layers separated by an insulating layer. This dimensional change from 2D to 3D architecture enables independent thickness control of each level while maintaining precise positioning through the structured arrangement of layers in the vertical dimension.
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 fabrication of micromechanical parts with high slenderness ratios and multiple levels with improved geometrical precision and reduced delamination, achieving parts like coaxial escape wheels with precise positioning and independent thicknesses.
Implementation Method 1
a substrate with electrically conductive top and bottom layers secured by an insulating intermediate layer
Implementation Method 2
patterns and recesses are etched to create cavities and recesses with insulating walls
Implementation Method 3
allowing directional etching and electrolytic deposition to avoid delamination
Data Source
AI summary
The invention concerns the field of micromechanical parts, in particular, for timepiece movements. The invention relates to a method of fabricating a mold that includes the following steps: (a) providing a substrate that has a top layer and a bottom layer made of electrically conductive, micromachinable material, and secured to each other by an electrically insulating, intermediate layer; (b) etching at least one pattern in the top layer as far as the intermediate layer to form at least one cavity in the mold; (c) coating the top part of the substrate with an electrically insulating coating; and (d) directionally etching the coating and the intermediate layer to limit the presence thereof exclusively at each vertical wall formed in the top layer.