Laser Structured Sensor Elements for High-Voltage Pressure Sensing
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Solution Overview
Problem
Existing sensor elements for pressure and force sensors require complex and costly wet-chemical structuring processes, limiting their long-term stability and high-voltage application suitability.
Innovation Solution
A method involving sub-picosecond laser structuring with broadband pulses to create meandering resistance structures and contact pads on a metallic substrate, using materials like NiCr or TiON, which allows for precise control of resistance and enhanced high-voltage dielectric strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet-chemical structuring processes are used to create strain gauges, then the functional layers can be structured, but the process becomes complex and costly with multiple expensive steps
Solution Approach 1:
The patent replaces wet-chemical structuring processes with laser structuring. The laser beam directly ablates or modifies the functional layers to create strain gauges, eliminating the need for photoresist coating, exposure, development, and chemical etching steps. This substitution of chemical processes with optical/thermal laser processing simplifies the manufacturing workflow while maintaining structuring precision.
Solution Approach 2:
The patent utilizes laser parameters (wavelength, pulse duration, power, scanning speed) to control the structuring process. By adjusting these parameters, the laser can selectively ablate or modify different materials (functional layers, insulating layers, substrates) without chemical agents, achieving precise structuring with a single integrated process instead of multiple chemical steps.
2Manufacturing precision
If conventional laser structuring is used, then structuring can be achieved, but interference effects occur that limit quality
Solution Approach 1:
The patent employs periodic pulsed laser action with specific pulse durations and repetition rates. The periodic pulsing allows controlled energy delivery to the material, preventing excessive heat accumulation and interference effects that would degrade structuring quality. The pulsed regime enables precise thermal management during laser processing.
Solution Approach 2:
The patent optimizes laser parameters including wavelength selection, pulse duration, peak power, and scanning speed to avoid interference effects. By carefully controlling these parameters, the laser interacts with the material in a regime that minimizes unwanted phenomena such as plasma formation, heat affected zones, and structural defects, thereby improving overall structuring quality.
3Productivity
If picosecond laser pulses are used for structuring, then material can be removed, but interference effects disrupt the process and limit quality
Solution Approach 1:
The patent transitions from picosecond to femtosecond pulsed laser operation, utilizing ultrashort pulses with durations in the 10-100 femtosecond range. This ultrafast periodic action removes material through cold ablation mechanisms before thermal diffusion and interference effects can develop, maintaining high productivity while eliminating quality-degrading interference phenomena.
Solution Approach 2:
The patent exploits phase transition mechanisms in the ultrashort laser pulse regime. The intense femtosecond pulses induce direct phase transitions (e.g., solid to plasma or vapor) without significant thermal intermediate states, enabling clean material ejection without the interference effects that plague longer pulse duration lasers. This phase transition approach maintains high material removal rates while improving quality.
4Manufacturing precision
If standard laser structuring is used, then meandering structures can be created, but high-voltage dielectric strength is compromised
Solution Approach 1:
The patent applies local quality modifications by using laser structuring to create precise insulating features at critical locations. The laser selectively modifies or removes material to form insulating barriers, trenches, or patterns that enhance dielectric strength specifically where needed, while maintaining the precision of meandering strain gauge structures in other areas. This localized approach preserves both structural precision and electrical insulation properties.
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 method simplifies the production of long-term stable sensor elements suitable for high-voltage applications, reducing production costs and avoiding interference effects that plague picosecond laser structuring, while achieving higher dielectric strength and improved sensor sensitivity.
Implementation Method 1
d) Partially ablating the material of the sensor function and contact layer using a laser such that strain gauges with a meandering resistance structure and contact pads remain
Data Source
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AI summary
To easily produce precise sensor elements, the invention provides a method for manufacturing a sensor element (10) for a pressure or force sensor, comprising the steps: a) providing a component (13) to be deformed, c) applying a sensor function and contact layer (24) made of a material with a k-factor between 2 and 10 to the component (13), d) removing the material of the sensor function and contact layer (24) over a surface using a laser such that strain gauges (44) with a meandering resistance structure and contact pads (46.1, 46.2, 46.3, 46.4) are formed.4) stop, wherein laser pulses from the group of laser pulses comprising • sub-ps laser pulses, • laser pulses from a broadband laser source (28) with a wavelength bandwidth of 10nm to 70nm, • laser pulses from a broadband laser source (28) with a fundamental wavelength and a wavelength bandwidth of at least 1%, preferably at least 2%, most preferably at least 3% of the fundamental wavelength, • laser pulses compressed by a pulse compression method, and • laser pulses guided through a hollow core fiber are used to remove the material.