Laser-Modified Glass Technical Mask Production

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Solution Overview

Problem

Existing methods for producing technical masks with open apertures, particularly using glass, face challenges such as breakability and the inability to create high-aspect-ratio structures due to isotropic etching, leading to deformation and micro-cracks under tensile stress, limiting their use in material application and removal processes.

Innovation Solution

A method involving laser-induced deep etching of transparent plate-shaped substrates, followed by anisotropic etching in a bath, allows for precise control of edge angles and avoids etching lips, enabling the use of glass substrates for technical masks that withstand tensile stress and maintain structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If glass substrates are used for technical masks, then scratch resistance, chemical resistance, and optical alignment capability are improved, but breakability and susceptibility to micro-cracks under tensile stress worsen

Engineering Contradiction:
Improvescratch resistance and chemical resistanceVSAvoidbreaking strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent changes the physical-chemical parameters of the glass substrate through laser-induced deep etching, creating a modified layer with different structural properties that increases breaking strength while maintaining other advantageous properties of glass

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical tensile stress application method with a different structural approach, using the laser-modified glass structure to inherently withstand stresses without requiring additional mechanical reinforcement

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

2Ease of manufacture

If isotropic etching is used to create mask openings, then manufacturing simplicity is improved, but manufacturing precision worsens due to undercut and etching lips

Engineering Contradiction:
Improveetching process simplicityVSAvoidopening shape precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces a laser-modified intermediate layer as a mediator between the etching resist and the bulk glass, which controls the etching process to achieve vertical walls without undercut while maintaining process simplicity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the etching parameters by creating a laser-modified zone with altered physical-chemical properties, enabling anisotropic etching behavior that produces precise vertical openings without the precision problems of conventional isotropic etching

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If conventional laser etching is used on glass, then manufacturing precision is improved, but the ability to create high-aspect-ratio structures worsens due to isotropic etching

Engineering Contradiction:
Improveopening dimension controlVSAvoidaspect ratio capability
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

The patent changes the physical-chemical parameters of the glass through laser-induced deep etching, creating a modified layer that enables anisotropic etching and allows formation of high-aspect-ratio structures with precise dimensional control

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure with a laser-modified glass layer combined with the bulk glass, where the modified layer provides directional etching properties that enable high-aspect-ratio openings while maintaining precision

Inventive Principle:
Principle #40Composite materials

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 glass technical masks with improved breaking strength, precision, and reliability for material application and removal processes, offering higher accuracy, hardness, and resistance to mechanical and chemical stress, while allowing for optical alignment and reduced deformation.

Implementation Method 1

the substrate is first modified with a laser beam along the contour of the opening

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

and is then anisotropically etched in an etching bath at the modified points

Methodology Applied
Scientific EffectAnisotropic etching:

Data Source

PatentEP3592501B1Method for producing a technical mask
Publication Date: 2021.10.06 LPKF LASER & ELECTRONICS AG
  • EP3592501B1 patent drawingFigure 1
  • EP3592501B1 patent drawingFigure 2
  • EP3592501B1 patent drawingFigure 3

AI summary

The invention relates to a method for producing a technical mask (1) from a flat substrate (2), for example glass, sapphire or silicon. At least one opening of the mask (1) is produced by means of laser-induced deep etching, wherein the substrate (2) is transparent at least for the laser wavelength used during laser-induced deep etching. To this end, the substrate (2) is modified by the pulses of the laser along predefined machining lines (4) for isolating in particular closed contours (3). Local interruptions in the machining lines (4) in the form of connecting webs, known as break-out tabs, ensure that the contours (3) to be isolated are still initially connected to the flat substrate (2) after treatment with the etching solution. In the subsequent step, the flat substrate (2) pretreated in this way is treated with an etching solution, such as hydrofluoric acid (HF) or potassium hydroxide (KOH), as a result of which the non-modified regions of the substrate (2) are etched homogeneously and isotropically. The modified regions react anisotropically in relation to the non-treated regions of the substrate (2) and therefore directed depressions are initially formed at the treated sites until ultimately the material of the substrate (2) is completely dissolved at said sites.