Laser processing technology has made enormous progress in recent years and enables the precise production of components for various applications. One area in which laser processing shows its strengths is the production of Hall probesfor air gap measurement in electric motors. In this article, we will take a closer look at the precise laser structuring of thin-film substrates for these probes and explain their importance for high-precision air gap measurement.
Current challenges in air gap measurement
Accurate measurement of the air gap between the rotor and the stator is crucial for the efficiency and performance of electric motors. The entire force of an electric motor is transmitted via the magnetic fields in the air gap. The thinner the air gap, the more efficient the power transmission. However, an air gap that is too thin is difficult to control mechanically and can lead to failures or premature wear. The exact magnetic field distribution in the air gap determines the power transmission. Precise measurement of this magnetic field distribution is therefore essential for the development of efficient and compact electric motors.
The role of Hall probes
Hall probes are a proven method for measuring magnetic fields and are used in many applications. In addition to the characterization and quality control of permanent magnets and the detection of cracks and material inhomogeneity on magnetized blanks, they are also used to measure static and dynamic magnetic fields, particularly in the air gap of electric motors. Traditional Hall sensors are too thick for this, however, and special packaging based on thin-film substrates is required.
Laser processing of thin film substrates
The thin-film substrates for Hall probes are processed using laser technology in the panel. This enables high-precision and cost-effective production of these probes. The process of laser structuring is used to functionalize component surfaces. Here, the laser is used to introduce the finest structures into the surface of the substrate with high precision in the micrometer range. These structures can include, for example, narrow slits or other specific patterns that improve the geometric placement and sensitivity of the sensors.
An ultrashort pulse laser is usually used for laser structuring. Thanks to so-called cold ablation, the material is not melted, but removed with a local plasma without leaving any residue, which enables high-quality structuring of the material. The material is not thermally stressed. As a result, ultrashort pulse lasers allow cleaner and post-processing-free micro structuring of surfaces with very high precision.
Advantages of laser structuring
Laser structuring offers a number of advantages over traditional mechanical processing methods.
Firstly, it enables the production of really thin, narrow and small substrates, which facilitates the integration of Hall probes in the tight installation spaces of electric motors.
Secondly, it enables the creation of complex, customized structures. The flexibility of the laser process also allows structuring to be carried out in different materials used for thin-film substrates, such as ceramic, silicon or glass.
Thirdly, laser patterning also offers high precision and reproducibility, resulting in improved quality and consistency of the Hall probes produced.
Fourthly, laser processing is a non-contact technology that minimizes the risk of damage to the substrates while increasing the efficiency of the Hall probe manufacturing process.
Further examples of laser microstructuring: Microfluidics
Extended processing step through wafer dicing
The individual probes are then sawn from the laser-structured panel using wafer dicing. This process describes the precision processing of substrates and wafers made of various materials such as ceramic, silicon, glass, germanium, sapphire, quartz, COB circuit boards or metal foils by means of mechanical separation grinding (sawing). The advantages of this processing are the extremely precise separation of the substrates, the exact edge quality and the variety of materials to be processed - including short set-up times.
Wafer sawing is carried out with saw blades that are guided through the substrate along the sawing or grooving lines in order to divide it into small probes by means of abrasive cutting, formatting or separating. This process step requires high precision in order to avoid damage and material residues on the probes and to ensure the full functionality of the end product.
Summary & future prospects
Laser processing technology, in particular laser structuring, offers an innovative solution for the production of Hall sensors for measuring small air gaps in electric motors. Thanks to the precision and flexibility of laser processing, thinner substrates can be used, which makes it easier to integrate the sensors into the limited installation space of electric motors. Laser processing enables the production of Hall probes for even more precise and reliable measurements, which in turn lead to an optimization of motor performance and improved efficiency. The ongoing development of laser processing technology will help to produce even more precise and efficient Hall probes, enabling even more accurate measurement of air gap and other applications.
What contribution does LCP Laser-Cut-Processing make?
In short: Full service from start to finish. This is because LCP supports its customers as a reliable manufacturing service provider and agile development partner, from initial technical advice and intensive process support to prototype production and series production along the entire process chain. Additional services such as measuring services and component cleaning as well as access to an extensive network of cooperation partners for alternative processing methods or surface finishing round off the whole package. In addition, with our many years of process expertise in the gentle laser fine machining of sensitive materials with the most delicate structures, we stand for high-class, precise machining and excellent component quality. Try us out and you will be impressed!
Would you like to find out more about Hall probes, magnetometers and mapping systems for magnetic measurements?
You can find extensive information from our partner Senis AG Switzerland at: https://www.senis.swiss
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