In addition to electric vehicles, hydrogen vehicles, better known as fuel cell cars, trucks and buses, can also be a promising alternative for zero-emission transportation. Here, a fuel cell with a hydrogen tank generates the electricity, which in turn is used to power the vehicle's electric drive. A decisive factor for the safe operation of such vehicles is the continuous monitoring of the pressure in the hydrogen tanks. Very compact and robust thin-film pressure sensors are usually used here, which enable precise measurement of pressures of up to 1000 bar. In addition, they must operate reliably in the demanding environment of the high-pressure hydrogen environment.
Material selection for robustness and thin-film technology for functionality
Use under challenging environmental conditions means that the housing of the sensors and the diaphragm of the measuring cell must be made of a particularly resistant material. Stainless steel 1.4435 is generally used here, as it guarantees outstanding mechanical stability (overload capacity) and resistance to extreme pressure conditions (burst pressure behavior). Furthermore, this material is an austenitic steel that does not become brittle on contact with hydrogen and therefore also has above-average corrosion and media resistance when handling aggressive media. In addition, the stainless steel housing and the stainless steel diaphragm must be directly welded, eliminating the need for additional seals. All these aspects are particularly important to ensure the longevity and reliability of the pressure sensors.
For the functionality of the pressure sensors, resistors are applied to the stainless steel diaphragm using thin-film technology. This can be done in a multi-stage coating process using sputter technology with a sometimes extremely thin layer thickness of less than 1 µm, which is then structured either directly by laser or using a wet-chemical process.
Precise laser processing for thin-film pressure sensors: expertise from LCP Laser-Cut-Processing GmbH
The production of pressure sensors with thin-film structures requires high-precision processing technology, including the use of laser technology. The latter requires many years of comprehensive expertise in the gentle laser processing of complex, delicate and sensitive precision components using various laser processing technologies, which are crucial in the manufacture of thin-film pressure sensors. And this is where LCP Laser-Cut-Processing GmbH comes into play as an expert and long-standing laser application center.
Our expertise lies in the wide range of laser processes paired with the procurement and processing of sensitive special materials as well as our continuous R&D activities for process development, innovative material processing or new processing technologies. The following processes are used to process stainless steel membranes or metallic circuit boards for pressure sensors:
- Laser fine cutting: Several individual membranes or circular blanks are cut from the metal foil or metallic circuit board using a laser. The advantage: Clean cut edges thanks to innovative fiber and disk lasers. Minimal degree formation can be easily removed by simple post-processing.
- Laser structuring: Structuring of coated components (de-coating or layer removal) or the creation of defined and complex surface structures as well as the creation of microstructures. The advantage: No or hardly any thermal damage to the material thanks to minimized heat input through USP laser technology. No burr formation or melt adhesion.
- Laser marking: Laser marking allows a data matrix or QR code to be applied to the respective component, which ensures complete traceability of the component. Advantage: Permanent marking that is resistant to abrasion and chemicals. Non-contact and therefore material-friendly process.
- Laser welding: With laser welding, the stainless steel membrane is permanently bonded directly to the sensor base body, the housing. Advantage: Non-contact process, no tool wear, high welding speed.
We also offer other laser technologies for a wide range of materials:
- Laser scribing: This involves the insertion of scribe lines for the mechanical separation of ceramic payloads in the individual components for the production of circuit carriers thanks to proven CO2 laser technology.
- Laser drilling: Laser drilling, also known as micro-drilling, is a non-contact and post-processing-free process for the insertion of precision holes, so-called vias, using USP laser technology.
In addition to laser processing, our range of services is rounded off by mechanical finishing technologies such as wafer dicing, milling, turning, bending/edging, brushing, precision finishing and glass bead blasting.
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