One-Piece Micromechanical Part Fabrication With Multi-Level Precision

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Solution Overview

Problem

Existing methods for manufacturing metal parts with multiple distinct functional levels are costly and difficult to implement, as they require precise alignment and stacking of layers, which increases production costs and complexity.

Innovation Solution

A method involving a silicon substrate with an electrically conductive surface, structuring a mold from photosensitive resin, electroplating to form a metal part, and selective machining to create a one-piece micromechanical part with at least two functional levels, allowing for precise positioning and reduced manufacturing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If successive LIGA processes are used to form metal parts with multiple functional levels, then manufacturing precision is improved, but device complexity and manufacturing cost increase significantly

Engineering Contradiction:
Improvedimensional precisionVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent merges the LIGA electroplating process with traditional machining operations into a single integrated manufacturing process. The metal part is first formed by electroplating in a LIGA mold to achieve high dimensional precision, then subsequently machined to create multiple functional levels. This combination eliminates the need for multiple sequential LIGA processes and their associated alignment requirements, thereby reducing process complexity while maintaining precision where needed.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The manufacturing process is segmented into distinct stages: first forming the base metal part through electroplating with high precision, then selectively machining specific regions to create functional levels. This segmentation allows each process to be optimized independently - electroplating for precision and machining for cost-effectiveness - rather than requiring all features to be created by the more complex multi-step LIGA process.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If successive LIGA processes are used to form metal parts with multiple functional levels, then manufacturing precision is improved, but manufacturing cost increases significantly

Engineering Contradiction:
Improvedimensional precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies different manufacturing qualities to different regions of the part. High-precision electroplating is applied to the base structure where dimensional accuracy is critical, while conventional machining is used for creating functional levels where extreme precision is less critical. This local differentiation of manufacturing quality reduces overall manufacturing cost by avoiding the high expense of successive LIGA processes throughout the entire part.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses a single LIGA mold for electroplating rather than requiring multiple expensive molds for successive LIGA processes. The mold is used once to form the base metal part, which is then completed by machining. This approach treats the LIGA mold as a disposable or single-use tooling element, eliminating the need for multiple precision molds and their associated costs.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If successive photolithographies and electroplating are used to form metal parts with multiple functional levels, then manufacturing precision is improved, but ease of manufacture deteriorates due to alignment requirements

Engineering Contradiction:
Improvepositioning accuracyVSAvoidalignment difficulty
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent performs the high-precision positioning action in advance during the electroplating stage, where the metal part is formed with precise dimensional accuracy in a single LIGA mold. Subsequent machining operations are performed on this pre-positioned base structure, eliminating the need for repeated alignment operations. The preliminary electroplating action establishes the precise geometric framework that guides all subsequent machining.

Inventive Principle:
Principle #10Preliminary action

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 approach reduces manufacturing costs and complexity while maintaining high precision in external and internal dimensions, making it easier to produce micromechanical parts with multiple functional levels.

Implementation Method 1

structuring a mold from a photosensitive resin to manufacture cavities

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

fill the cavities of the mold by electroplating to form a metal part

Methodology Applied
Scientific EffectElectroplating: Electroplating

Data Source

PatentEP2767870B1Method for manufacturing a one-piece micromechanical part comprising at least two separate functional levels
Publication Date: 2019.06.05 NIVAROX FAR SA
  • EP2767870B1 patent drawingFigure 1~7
  • EP2767870B1 patent drawingFigure 8~10
  • EP2767870B1 patent drawingFigure 11~13

AI summary

The method involves forming a silicon substrate including an electrically conductive top surface. A mold is structured from photosensitive resin to form cavities with a base formed by the electrically conductive top surface by depositing a photosensitive resin layer on the conductive top surface. The cavities of the mold are filled by galvanoplasty to form a metal part (21). A portion of the metal part is selectively machined to form a single-piece micromechanical component having distinct functional levels. The component is released from the substrate and the photosensitive resin. The metal part is formed from a nickel phosphorus base. An independent claim is also included for a timepiece.