LIGA-UV Metal Microstructures with Dual-Layer Galvanic Coating

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Solution Overview

Problem

Existing methods for manufacturing metal microstructures using LIGA technology face challenges in achieving cost-effective mass production with precise geometric dimensions and optimal material properties for specific applications, as they often rely on expensive equipment and result in microstructures made of single metals like nickel, which may not have ideal mechanical and tribological properties.

Innovation Solution

A method involving the use of LIGA-UV process to create a microstructure with a core of a first metal coated by a second metal, where the precision of geometric dimensions is defined by photolithography, allowing for the selection of metals with different properties to optimize mechanical and tribological characteristics, such as using nickel-phosphorus for low friction and nickel for mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If LIGA technology using synchrotron is used, then manufacturing precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvegeometric precisionVSAvoidequipment complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces expensive, complex synchrotron equipment with simpler, more accessible UV light sources and photomasks. The photomask acts as a disposable or reusable template that defines the microstructure geometry, eliminating the need for complex synchrotron radiation systems while maintaining manufacturing precision through the photolithography process.

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

Solution Approach 2:

The patent substitutes the complex mechanical and optical system of synchrotron radiation with a simpler photolithography system using UV light sources, photomasks, and chemical development processes. This replacement maintains geometric precision while dramatically reducing device complexity and cost.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If single metal microstructures are used, then manufacturing simplicity is improved, but adaptability worsens

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidmaterial property optimization
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent applies different metal materials to different regions or layers of the same microstructure. The core is made of one metal (e.g., nickel-phosphorus for low friction) while the coating is made of another metal (e.g., nickel for mechanical strength). This allows each region to have optimized properties for its specific function while using the same manufacturing process.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent creates composite metal microstructures by combining two or more different metals in a single component. The core material provides base structural properties while the coating material provides surface-specific properties, achieving a combination of mechanical strength, tribological performance, and electrical conductivity that cannot be obtained with a single metal.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If core metal is coated with second metal by vacuum vaporization, then material property optimization is improved, but manufacturing precision worsens

Engineering Contradiction:
Improvematerial property optimizationVSAvoidgeometric precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent performs the coating operation during the galvanic deposition process itself, before the structure is released from the mold. The photoresist mold remains in place as a physical constraint, ensuring that the coating metal is deposited only within the defined geometric boundaries. This preliminary coating, done while the mold is still present, maintains geometric precision without requiring post-processing steps.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses the photoresist mold as an intermediary structure that maintains geometric precision during the coating process. The mold acts as a physical barrier and template, ensuring that the galvanic deposition of the coating metal occurs only within the intended geometric boundaries, thereby preserving manufacturing precision throughout the multi-material fabrication process.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enables the production of microstructures with controlled geometric precision and tailored mechanical properties, suitable for applications like toothed wheels and timepiece components, while being simple and cost-effective.

Implementation Method 1

irradiating the resin layer through a mask defining the outline of the desired microstructure

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

galvanically and uniformly depositing a layer of a first metal from said conductive layer of the substrate and from a conductive face of the photoresist layer

Methodology Applied
Scientific EffectGalvanic deposition: Electrodeposition

Data Source

PatentEP2229470B1Method for obtaining a metal microstructure and microstructure obtained according to said method
Publication Date: 2011.11.16 NIVAROX FAR SA
  • EP2229470B1 patent drawingFigure 1~8

AI summary

The invention relates to a method for making a metal microstructure, characterised in that it comprises the steps of forming, by a LIGA-UV method, a mould made of a photosensitive resin, and galvanically and uniformly depositing a layer of a first metal then a layer of a second metal in order to form a block that substantially reaches the upper surface of the photosensitive resin.