Sensor device and method for producing a sensor device
By using a sensor design with ceramic materials and an inorganic protective layer, the problems of sensor migration and corrosion in high-temperature and corrosive media have been solved, resulting in a temperature sensor with high stability and fast response, reducing manufacturing costs and meeting environmental standards.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TDK ELECTRONICS AG
- Filing Date
- 2024-07-24
- Publication Date
- 2026-04-17
AI Technical Summary
Existing temperature sensors suffer from migration, corrosion, and response time delay when used in corrosive media, especially in high-temperature and humid environments, where existing organic coatings cannot provide sufficient stability and durability.
The sensor element uses ceramic materials, combined with non-precious metal electrodes and connecting elements, and uses an inorganic protective layer and hydroxide coating layer. The corrosion-resistant and moisture-resistant protective layer is formed by anodizing or chemical coating methods to ensure that the sensor can work stably in high temperature and corrosive media.
It achieves long-term stability and rapid response of the sensor in high temperature and corrosive media, reduces manufacturing costs, meets environmental protection standards, and avoids the use of precious metals.
Smart Images
Figure CN121889647A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a sensor device, particularly a temperature sensor device. The invention also relates to a method for manufacturing at least one sensor device, preferably a temperature sensor. Background Technology
[0002] The ever-increasing demands on temperature sensors in terms of long-term media tolerance, operating temperature, and robustness require a particularly stable enclosure for the sensor, which should be combined with a shortened response time as much as possible.
[0003] For the installation of encapsulated, glass-encapsulated sensors in a system, the highest possible dimensional stability is required, which cannot currently be achieved through existing additional organic-based coatings. Currently used organic coatings (typically fluorine-based compounds) with high moisture and media resistance can strongly delay, but not completely or permanently prevent, migration or corrosion of sensor elements.
[0004] According to existing technology, temperatures used for monitoring and regulation in various applications are primarily measured using ceramic thermal conductor thermistors (NTCs), silicon temperature sensors (KTYs), platinum temperature sensors (PRTDs), or thermocouples (TCs). Among these, NTC thermistors are the most widely used due to their low manufacturing cost. Another advantage over thermocouples and metal resistive elements, such as Pt elements, is their pronounced negative resistance-temperature characteristic.
[0005] For sufficient mechanical stability and to protect against external influences, as well as to avoid corrosion caused by corrosive media and material changes in NTC materials caused by gas atmospheres or in electrodes caused by temperature, ceramic sensor elements are provided with a cover made of polymer or glass.
[0006] In the case of a pure polymer-coated portion (based on epoxy resin), the maximum operating temperature of this element is limited to approximately 150°C-175°C, and in the case of a glass-coated portion with an additional polymer layer (based on PFA), the maximum operating temperature of this element is limited to approximately 260°C.
[0007] However, such sensor elements cannot be used sustainably for extended periods in particularly humid environments or corrosive media. After a short time, the polymer begins to degrade, or a thin gap forms between the metal wire and the coating due to the different coefficients of thermal expansion of the materials (ceramic-metal-polymer). Moisture or corrosive media can penetrate and trigger migration processes, especially when voltage is applied.
[0008] However, in order to still be usable in corrosive media, the sensor element is mounted, for example, in a plastic or stainless steel housing. Additionally, potting material is used very frequently to establish thermal contact with the element. A major drawback of such a system is the delayed response time caused by heat transfer due to the additional structure and the limited thermal conductivity of the materials used. Summary of the Invention
[0009] The purpose of this invention is to describe a sensor device and a method for manufacturing the sensor device, which solve the problems mentioned above.
[0010] The objective is achieved by the sensor device according to the independent claims and the method for manufacturing the sensor device.
[0011] Describe a sensor device based on one aspect. The sensor device is suitable for measuring temperature. The sensor device is a temperature sensor device.
[0012] The sensor device has a sensor element. The sensor element is made of ceramic material. The sensor element preferably has an NTC sensor chip.
[0013] The sensor device also has at least two electrodes, preferably exactly two electrodes (a first electrode and a second electrode). The electrodes are used for electrical contact with the sensor element. The electrodes are fixedly connected to the surface of the sensor element. The electrodes are preferably sputtered onto the upper and lower sides of the sensor element.
[0014] The sensor device also has at least two, preferably exactly two, connecting elements. Each connecting element has a first end region and a second end region.
[0015] The first end region is flattened. The corresponding connecting element is electrically and mechanically connected to the sensor element, particularly to the corresponding electrode, in the first end region, for example, by means of welding or soldering. The second end region is constructed and positioned for electrical contact with the sensor device. The second end region forms the end of the corresponding connecting element that is opposite to the sensor element.
[0016] The sensor device also has a cover. The cover may be, for example, glass, preferably lead-free glass. In this case, the sensor device is absolutely not a concern for the environment and does not require hazardous waste disposal.
[0017] Alternatively, the covering may also be a polymer, such as epoxy resin, polyurethane, silicone resin, PEEK (polyether ether ketone), PFA (perfluoroalkoxy polymer), or Teflon, or a combination of the aforementioned materials.
[0018] The covering completely surrounds at least the first end region (hereinafter also referred to as the connection portion) of the sensor element, electrode and connecting element.
[0019] The sensor device also has a separate, non-conductive inorganic protective layer. "Separate" in this context should be understood as meaning that the protective layer is a separate component independent of the covering portion. Specifically, the protective layer has a different material and / or a different stretch and / or is constructed using a different method than the covering portion. The protective layer is non-metallic; in other words, it does not possess metallic conductivity.
[0020] The protective layer protects the sensor device from external influences, and especially the connecting elements, from corrosive media or gases. The protective layer is corrosion-resistant and moisture-resistant. It has a small thickness.
[0021] The protective layer at least completely surrounds the non-covered areas of the connecting element, except for the second end region. In other words, the second end region does not have a protective layer.
[0022] The area between the second end region and the covered portion is covered, especially completely surrounded, by a protective layer. Here, the protective layer is directly attached to the covered portion.
[0023] Furthermore, the remaining areas of the corresponding connecting elements (the first end area / connection portion) can also be surrounded by a protective layer. In particular, it is feasible for the entire sensor device (sensor element, electrode, cover, connecting element) except for the second end area to be covered by a protective layer.
[0024] The protective layer extends along the connecting element more than the covering portion extends along the connecting element. This means that the protective layer surrounds a larger (especially longer) area of the connecting element compared to the covering portion.
[0025] The protective layer enables the sensor device to be used even in corrosive media and at temperatures up to 400°C. This provides an exceptionally durable sensor device. Through the specially designed protective layer, the sensor device also exhibits high electrical insulation strength. Furthermore, due to its good thermal conductivity and the small thickness of the protective layer, the sensor device has a short response time. Moreover, the sensor device is made from particularly cost-effective and RoHS / REACH compliant (lead-free) materials.
[0026] According to one embodiment, the protective layer is produced by anodizing, for example, by anodizing in the case of Al-clad connecting elements. In this case, instead of coating an additional layer, the uppermost layer of the connecting element (e.g., Al, Cr, or Ni) is transformed to form a (multi-layered) protective layer.
[0027] In the described embodiment, the area between the second end region and the cover portion of the corresponding connecting element may be surrounded only by the protective layer. Here, the protective layer is directly attached to the cover portion. However, alternatively, the protective layer may also surround—except for the second end region—the entire sensor device, including the cover portion.
[0028] By creating an anodic protective layer, very thin oxide / hydroxide layers with very high mechanical abrasion resistance can be fabricated with great precision and reproducibility. This enables highly accurate and robust sensor devices.
[0029] In an alternative embodiment, the protective layer can be produced by a purely chemical coating method or by chemical vapor deposition. In this case, the protective layer is an additional layer applied to the outside of the connecting element. Alternatively, the protective layer can be applied to the remaining components of the sensor device. Therefore, in this embodiment, the protective layer can also surround the entire sensor device except for the second end region.
[0030] The protective layer produced by the method mentioned above is inorganic. It is non-conductive and non-metallic. The protective layer is characterized by being a purely oxidized compound (metal oxide), nitrided, carbide, halogenated, or phosphate compound, such as Al₂O₃, Cu. x O y Cr x O y Mo x O y TiO2, V x O y The protective film formed by SiO2 is very thin, which results in a short response time and good thermal conductivity—accompanied by high long-term stability of the sensor device.
[0031] According to one embodiment, the sensor device further comprises an additional hydroxide coating layer. In this context, "additional" should be understood as a separate component independent of the covering and protective layers. Specifically, the coating layer may be made of a different material and / or with a different stretching and / or constructed by a different method and / or separate / independent method steps compared to the covering and protective layers.
[0032] The additional covering layer is formed by another surface treatment (hydrothermal treatment) of the sensor device. The covering layer is continuous. In particular, the hydroxide covering layer preferably covers the entire sensor device except for the corresponding second end region. There are no gaps / gaps in the covering layer or between the covering layer and other components of the sensor. Therefore, the covering layer is continuous and tight.
[0033] The cover layer serves as an additional protective element and further enhances the durability of the sensor device. Furthermore, the cover layer allows for better bonding of the protective layer to the enclosure. This is particularly advantageous when the protective layer does not extend across the entire sensor device but is only formed on the connecting elements. In this case, a gap may appear between the protective layer and the enclosure. This gap can be covered by the additional cover layer.
[0034] According to one embodiment, the sensor device does not contain precious metals. In particular, the connecting elements are made of a material free of precious metals. Furthermore, the electrodes are made of a material free of precious metals. Because the sensor device does not contain precious metals, it can be manufactured particularly cost-effectively.
[0035] According to one embodiment, the sensor element is based on perovskite in the Y-Ca-Cr-Al-(Sn)-O system or spinel in the Ni-Co-Mn-(AlFe)-(Cu)-(Zn)-(Ca)-(Zr)-(Ti)-(Mg)-O system. The material selection depends on the operating temperature and resistive characteristics. For operating temperatures up to 300°C, sensor materials with spinel structures having the general chemical formula AB₂O₄ or B(A,B)O₄, such as Co₃-(x+y)Ni, can be used. x Mn y O4, where x = 1.32 and y = 1.32. High-temperature stable ceramic materials with a perovskite structure having the general chemical formula ABO3 are suitable for high application temperatures (>300°C), for example, those with the composition (Y1-xCa...). x (Cr1-yAl) y O3, a ceramic material in which x = 0.03 and 0.05 and y = 0.85.
[0036] This provides a sensor device that can be used very flexibly to meet the needs of different application areas.
[0037] According to another aspect, a method for manufacturing at least one sensor device is described. It should be noted that the method preferably produces multiple sensor devices in parallel. For simplicity, the following description essentially refers to a single sensor device.
[0038] Preferably, the sensor device described above is manufactured by the method described above. All characteristics disclosed with respect to the sensor device or method are also correspondingly disclosed with respect to other relevant aspects and vice versa, even if the relevant characteristics are not mentioned in detail in the context of the relevant aspect. The method comprises the following steps:
[0039] A) Provide at least one sensor element. The sensor element preferably has an NTC sensor chip. The sensor element preferably has a ceramic material. Particularly preferably, the sensor element is based on a perovskite structure in the Y-Ca-Cr-Al-(Sn)-O system or a spinel structure in the Ni-Co-Mn-(Al)-(Fe)-(Cu)-(Zn)-(Ca)-(Zr)-(Ti)-(Mg)-O system.
[0040] B) Provide or constitute at least two electrodes. Preferably, the electrodes are sputtered onto opposite sides (e.g., upper and lower sides) of the sensor element. The electrodes are used for electrical contact with the sensor element. Different metals or metal pairs, such as Al, Ni, Cu, Cr, Mo, Ti, V, or Ni-Al, Ni-Cu, Ni-Cr, Ni-Mo, Ni-Ti, can be applied to the electrodes. In particular, the electrodes are preferably free of noble metals.
[0041] C) At least two connecting elements are provided. Each connecting element has a first end region and a second end region. The connecting element preferably has a connecting metal wire. The connecting element may, for example, have a core and a sheath. The sheath may, for example, be made of Al, Cr, Ni, or Cu. The connecting element is preferably made of a temperature-stable material with low corrosion resistance. The connecting element is preferably free of precious metals.
[0042] D) Secure the first end region of the connecting element to the sensor element, particularly the electrodes of the sensor element (i.e., forming the connection point). The connecting element and the electrodes of the sensor element are connected by soldering or brazing. Different soldering methods can be used depending on the material mating, such as ultrasonic welding, resistance welding, thermal diffusion welding, or plasma welding. In the case of brazing, additional solder is necessary. Optionally, the electrodes can be plasma cleaned before securing the connecting element to the electrodes.
[0043] E) Constructing a covering portion. The covering portion is configured such that it completely covers at least a first end region of the sensor element, electrode, and connecting element (i.e., especially the connection portion). The covering portion may be made of glass or polymer. The coefficient of thermal expansion and melting or softening temperature of the material of the covering portion are matched with the coefficient of thermal expansion or melting temperature of the materials of the connecting element and the sensor element.
[0044] F) Constructing a protective layer. The protective layer is constructed by anodizing, chemical coating, or deposition from the vapor phase. The protective layer is configured such that it at least completely surrounds the non-covered areas of the connecting element, except for the second end region. The protective layer may also surround the entire sensor device except for the second end region, which is configured to contact the sensor device. The second end region is not anodized or coated. This is ensured by masking the second end region or subsequently exposing (peeling) it.
[0045] The protective layer allows the sensor device to be used at higher application temperatures up to 400°C (including boundary values) and in particularly corrosive media or gases. By creating the anodic protective layer, very thin oxide / hydroxide layers with very high mechanical abrasion resistance can also be manufactured with great precision and reproducibility. Furthermore, this highly robust sensor device exhibits a very short response time.
[0046] In summary, the method described herein produces cost-effective, durable, robust, and highly efficient sensor devices.
[0047] According to one embodiment, annealing or hydrothermal treatment is performed in another step (G) to form an additional hydroxide coating layer. The hydroxide coating layer completely covers the entire sensor device except for the second end region.
[0048] The durability and robustness of the sensor device can be further improved by using a cover layer.
[0049] According to one embodiment, prior to step F), a protective varnish is applied to the second end region and allowed to harden. This ensures that the second end region of the corresponding connecting element remains unprotected. In another step—after the protective layer is applied—the second end region of the connecting element with the protective varnish is exposed again (peeling). Attached Figure Description
[0050] The accompanying figures described below should not be construed as being to scale. Rather, for better illustration, individual dimensions may be shown enlarged, reduced, or even distorted.
[0051] Elements that are identical or have the same function are indicated by the same reference numerals.
[0052] The attached diagram shows:
[0053] Figure 1 This shows a cross-sectional view of the sensor device before the protective layer is formed.
[0054] Figure 2 A cross-sectional view of a sensor device with a protective layer according to a first embodiment is shown.
[0055] Figure 3 A cross-sectional view of a sensor device with a protective layer according to another embodiment is shown. Detailed Implementation
[0056] Figure 1 A cross-sectional view of the sensor device 1 before forming the protective layer 8 according to the invention is shown. The sensor device 1 is a temperature sensor device. The sensor device 1 is specifically designed for use at high temperatures up to 400°C (including boundary values). The sensor device 1 is configured for use in corrosive media or gases.
[0057] The sensor device 1 has a sensor element 2, preferably an NTC sensor chip. The sensor element 2 is made of a ceramic material. In particular, the sensor element 2 is based on perovskite in the Y-Ca-Cr-Al-(Sn)-O system or spinel in the Ni-Co-Mn-(Al)-(Fe)-(Cu)-(Zn)-(Ca)-(Zr)-(Ti)-(Mg)-O system.
[0058] The choice of material for sensor element 2 depends on the intended operating temperature and resistivity characteristics. For operating temperatures up to 300°C, sensor materials with spinel structures, such as Co3-(x+y)Ni, with the general chemical formula AB2O4 or B(A,B)O4, can be used. x Mn y O4, where x = 1.32 and y = 1.32. High-temperature stable ceramic materials with a perovskite structure having the general chemical formula ABO3 are suitable for high operating temperatures (>300°C), for example, those with the composition (Y1-xCa...). x (Cr1-yAl) y O3, a ceramic material in which x = 0.03 and 0.05 and y = 0.85.
[0059] Two electrodes 3a and 3b (first electrode 3a and second electrode 3b) are formed, and particularly sputtered, on opposite sides (upper and lower sides) of sensor element 2. Electrodes 3a and 3b do not contain noble metals. Different metals or metal pairs can be considered as materials for electrodes 3a and 3b. Examples of materials conceivable are Al, Ni, Cu, Cr, Mo, Ti, V, or Ni-Al, Ni-Cu, Ni-Cr, Ni-Mo, and Ni-Ti. Specifically, the first (upper) electrode 3a can, for example, be aluminum. The second (lower) electrode 4b can, for example, be nickel.
[0060] The sensor device 2 also has two connecting elements 4, such as connecting metal wires. The connecting elements 4 do not contain precious metals. Preferably, the connecting elements 4 are made of a temperature-stable material with low corrosion tendency. Connecting elements 4 can be made of non-precious metals, such as Ni, Al, or Cu, or of steel alloys with high Fe, Cr, and / or Ni content, as well as sheathed connecting elements 4, such as connecting elements 4 with an Fe-Ni / Cr core and a Cu sheath or an Fe-Ni / Cr core and an Al sheath, and connecting elements 4 with an Fe-Ni / Cr core and a coating, such as Mo, Ti, or V.
[0061] exist Figures 1 to 3 In the middle, the connecting element 4 has a core-sheath structure, such as an Fe / Ni core 6 and an Al sheath 5 ( Figure 2 ) or Fe / Ni core 6 and Cu sheath 5 ( Figure 3 Of course—as detailed above—other materials or combinations of materials are also possible.
[0062] The connecting element 4 has an elongated shape. Specifically, the connecting element 4 extends along the main longitudinal axis X of the sensor device (see [reference needed]). Figure 2 The extension of the connecting element 4 is greater than that of the connecting element 4 in the direction transverse to the main longitudinal axis X. The connecting element 4 has a first end region 4a and a second end region 4b.
[0063] The first end region 4a is flattened and connected to the electrodes 3a and 3b, for example, by welding or brazing. Specifically, a connection point between the connecting element 4 and the sensor element 2 is formed at the location of the first end region 4a. Depending on the materials used for the connecting element 4 and the electrodes 3a and 3b, different welding methods can be used to connect the connecting element 4 and the electrodes 3a and 3b, such as ultrasonic welding, resistance welding, thermal diffusion welding, or plasma welding. In the case of brazing, additional brazing filler is necessary.
[0064] The corresponding connecting element 4 transitions into a circular cross-sectional shape between the first end region 4a and the intermediate region. The opposite free ends of the corresponding connecting element 4 form a corresponding second end region 4b. The second end region 4b constitutes a contact sensor device 1. The corresponding second end region 4b has a length l.
[0065] The sensor device 1 also has a covering portion 7. The covering portion 7 completely surrounds the sensor element 2, the electrodes 3a and 3b, and the first end region 4a of the connecting element 4, thereby also completely surrounding the connection portion mentioned above between the connecting element 4 and the sensor element 2. The covering portion 7 is used to protect the sensor device 1 from external influences.
[0066] The covering portion 7 may be made of lead-free glass or a polymer (epoxy resin, polyurethane, silicone resin, PEK, PFA, or Teflon, or a combination of said materials). The material used for the covering portion 7 is matched in coefficient of thermal expansion and melting or softening temperature to the material used for connecting element 4 and sensor element 2.
[0067] According to Figure 2 and Figure 3 In the embodiment shown, the sensor device 1 according to the present invention also has a protective layer 8. The protective layer 8 is used to improve the robustness, durability, and flexibility of the sensor device 1. The protective layer 8 is also configured to give the sensor device 1 a very short response time.
[0068] The protective layer 8 can be produced by anodizing methods, such as anodizing in the case of Al-clad connecting elements 4, by purely chemical coating methods, or by deposition from the vapor phase. The protective layer 8 is made of inorganic material. The protective layer 8 is non-conductive. The protective layer 8 is non-metallic.
[0069] The protective layer 8 has an oxide layer. Preferably, the protective layer 8 has a purely oxidized compound (metal oxide), a nitrided, carbinated, halogenated, or phosphate compound. For example, the protective layer 8 has Al2O3, Cu... x O y Cr x O y Mo x O y TiO2, V x O y Or SiO2. The protective layer 8 has a small thickness, which results in a short response time and good thermal conductivity for the sensor device 1.
[0070] According to Figure 2 In the embodiment shown, the protective layer 8 completely surrounds the connecting element 4 in the region between the covering portion 7 and the second end region 4b. Here, the protective layer 8 is preferably directly attached to the covering portion 7.
[0071] Compared to the covering portion 7, the protective layer 8 covers or surrounds a longer (larger) area of the connecting element 4. Therefore, the extension A1 of the protective layer 8 along the connecting element 4 is greater than the extension A2 of the covering portion 7 along the connecting element 4: A1 > A2. As mentioned above, in Figure 2 In the embodiment shown, the protective layer 8 is directly connected to the covering portion 7. In other words, except for the second end region 4b, each region of the sensor device 1 is either covered by the covering portion 7 or by the protective layer 8.
[0072] However, the protective layer 8 can not only cover the connecting element 4, but also surround the entire sensor device 1 except for the second end region 4b. Figure 3 In this configuration, the protective layer 8 completely surrounds the covering portion 7 and the components disposed within the covering portion (sensor element 2, electrodes 3a, 3b, first end region 4a / connection portion), as well as the remaining areas of the connecting element 4, except for the second end region 4b. In each embodiment, the second end region 4b does not have the protective layer 8 to allow contact with the sensor device 1. In other words, the protective layer 8 does not extend along the length l of the second end region 4b.
[0073] According to Figure 3 In the embodiment shown, the sensor device 1 may also have an additional hydroxide coating layer 9. The coating layer 9 is produced by an additional surface treatment of the sensor device 1 and completely surrounds the sensor device 1, including the covering portion 7 and the protective layer 8, except for the second end region 4b. The additional coating layer 9 serves to better bond the protective layer 8 to the covering portion 7. The coating layer is continuous and tight, thereby covering any possible gaps between the protective layer 8 and the covering portion 7.
[0074] More specifically, the sensor device 1 according to the invention can be constructed, for example, as follows (specific embodiments are not shown in detail):
[0075] NTC chip 2 with sputtered Ni-Al electrodes 3a and 3b;
[0076] Welded connecting element 4 (sheath part - metal wire; Fe-Ni core and Al sheath part);
[0077] Pb-free glass-clad portion 7 (melting temperature lower than the melting temperature of Al, i.e., <660°C);
[0078] The connecting element (metal wire) 4 is anodized after glass encapsulation, thereby forming a dense, multi-layered protective layer 8 through anodizing;
[0079] In the unanodized area at the second end region 4b, the sensor device 1 is electrically contacted;
[0080] An additional hydroxide coating 9, caused by hydrothermal treatment, is applied to the entire device 1 (including the glass covering 7) except for the second end region 4b, to better bond to the glass covering 7, and in particular to close any possible gaps between the covering 7 and the protective layer 8.
[0081] The sensor device 1 thus obtained has a protective layer composed of Al2O3 / AlO(OH) / Al(OH)3.
[0082] Alternatively, the sensor device 1 according to the present invention can be constructed, for example, as follows:
[0083] NTC chip 2 with sputtered Ni-Cu electrodes 3a and 3b;
[0084] Welded connecting element 4 (sheath part - metal wire; Fe-Ni core and Cu sheath part);
[0085] Glass-clad section 7;
[0086] A chromium oxide protective layer 7 (formed by electroplating after glass encapsulation) surrounds the entire sensor device 1 except for the second end region 4b;
[0087] An additional hydroxide coating 9, caused by hydrothermal treatment, is applied to the entire device 1 (including the glass covering 7) except for the second end region 4b, to better bond to the covering 7.
[0088] The stripped metal wire end (second end region 4b) is used to remove the protective layer 8 / covering layer 9 for electrical contact.
[0089] The sensor device 1 with a non-conductive, non-metallic inorganic protective layer 8 has the following advantages:
[0090] Migration resistance is achieved through a corrosion-resistant, moisture-resistant, non-conductive inorganic protective layer 8.
[0091] High electrical insulation strength;
[0092] The short response time is achieved through good thermal conductivity and a very thin protective layer 8.
[0093] Cost-efficient, because it does not use precious metals;
[0094] Compliant with RoHS / REACH (lead-free).
[0095] A method for manufacturing the sensor device 1 described above is described below. The method includes the following steps:
[0096] A) Provide sensor element 2. Sensor element 2 preferably has an NTC sensor chip. Sensor element preferably has a ceramic material.
[0097] B) Provide or form at least two electrodes 3a and 3b. Electrodes 3a and 3b are preferably sputtered onto the upper and lower sides of the sensor element 2. Electrodes 3a and 3b do not contain precious metals.
[0098] Subsequently, electrodes 3a and 3b can (optionally) be plasma cleaned.
[0099] C) A connecting element 4 is provided, having a first end region 4a and a second end region 4b. The connecting element 4 is made of a temperature-stable material with low corrosion tendency. The connecting element 4 does not contain precious metals.
[0100] D) Secure the first end region 4a of the connecting element 4 to the electrodes 3a and 3b of the sensor element 2 (i.e., form the connection point) to make electrical contact with the sensor element 2. Depending on the material used, different welding methods can be used as the fastening method, such as ultrasonic welding, resistance welding, thermal diffusion welding, or plasma welding. Alternatively, the connecting element 4 can be fastened to the electrodes 3a and 3b by means of hard soldering.
[0101] E) A covering portion 7 is formed such that the covering portion 7 completely covers at least the first end region 4a of the sensor element 2, electrodes 3a, 3b and connecting element 4 (i.e., especially the connecting portion). The covering portion 7 may be made of lead-free glass. Alternatively, the covering portion 7 may be made of polymer.
[0102] To form the polymer-coated portion, the sensor head (including the sensor element 2, including the connection portion) of the sensor device 1 is covered with a polymer. Here, the polymer can be epoxy resin, polyurethane, silicone resin, PEK, PFA, or Teflon, or a combination of these materials. The polymer coating can be applied by an impregnation method or a powder coating method. The polymer is then allowed to harden.
[0103] After method step E), there exists such as Figure 1 The device shown in the figure.
[0104] Subsequently, a protective varnish may (optionally) be applied to the second end region 4b and allowed to harden, thereby facilitating the subsequent formation of the protective layer 8 (see [link]). Figure 2 and Figure 3 Ensure that the second end region 4b remains without the protective layer 8.
[0105] F) Constitutes the protective layer 8. The protective layer can be applied or produced locally. Therefore, the protective layer 8 is formed particularly by anodizing, chemical coating or deposition from the vapor phase.
[0106] In the anodizing process, either the entire device 1 (except for the second end region 4b) or only a portion of the connecting element 4 is introduced into the acid bath, and a voltage is subsequently applied to form the protective layer 8. Alternatively, the (glass) cladding 7 can be introduced into the acid bath. Here, the glass corrodes, and hydroxide is deposited on the surface of the cladding 7.
[0107] The protective layer 8 is configured such that it at least completely surrounds the area of the connecting element 4 that does not have a covered portion 7, except for the second end region 4b. Figure 2 The protective layer 8 may also surround the entire sensor device 1 except for the second end region 4b, which is configured for electrical contact with the sensor device 1. Figure 3 ).
[0108] G) Annealing or hydrothermal treatment is performed to form an additional hydroxide coating layer 9 (optional). The hydroxide coating layer 9 completely covers the entire sensor device 1 except for the second end region 4b. Figure 3 ).
[0109] As described, the second end region 4b is not anodized or coated. This is ensured by, for example, a protective varnish for the second end region 4b mentioned above, which is then removed after the application of the protective layer 8 or the cover layer 9. Alternatively, the protective layer 8 or the cover layer 9 can be applied by means of a mask, instead of using a protective varnish.
[0110] The description of the subject matter presented herein is not limited to any particular implementation. Rather, the features of the various implementations—provided it is technically meaningful—can be combined with each other arbitrarily.
[0111] List of reference numerals
[0112] 1. Sensor device
[0113] 2. Sensor Components
[0114] 3a (First) Electrode
[0115] 3b (Second) Electrode
[0116] 4 Connecting elements
[0117] 4a First end region
[0118] 4b Second end region
[0119] 5. Packaging Section
[0120] 6 core
[0121] 7. Covering section
[0122] 8. Protective layer
[0123] 9. Covering layer
[0124] A1 Protective Layer Extension
[0125] A2 Extension of the covering part
[0126] X Main longitudinal axis
[0127] Length of the second end region
Claims
1. A sensor device (1) for measuring temperature, the sensor device comprising: - Sensor element with ceramic material (2). - At least two electrodes (3a, 3b) are used for electrical contact with the sensor element (2). - At least two connecting elements (4), each having a first end region (4a) and a second end region (4b), wherein the corresponding connecting element (4) is electrically and mechanically connected to the corresponding electrodes (3a, 3b) in the first end region (4a), and wherein the second end region (4b) is configured and arranged for electrical contact with the sensor device (1). - Covering portion (7), wherein the covering portion (7) completely covers the sensor element (2), the electrodes (3a, 3b) and at least the first end region (4a). - A separate, non-conductive inorganic protective layer (8), wherein the protective layer (8) at least completely surrounds the area of the connecting element (4) that does not have the covering portion (7), except for the second end region (4b).
2. The sensor device (1) according to claim 1. The protective layer (8) extends (A1) along the connecting element (4) in a manner greater than the covering portion (7) extends (A2) along the connecting element (4).
3. The sensor device (1) according to any one of the preceding claims. The protective layer (8) completely covers the entire sensor device (1) except for the corresponding end region (4b).
4. The sensor device (1) according to any one of the preceding claims. The protective layer (8) is produced by anodizing, by a purely chemical coating method, or by deposition from the gas phase.
5. The sensor device (1) according to any one of the preceding claims. The protective layer (8) therein has an oxidized, nitrided, carbonized, halogenated or phosphate compound.
6. The sensor device (1) according to any one of the preceding claims. The protective layer (8) contains Al2O3 and Cu. x O y Cr x O y Mo x O y TiO2, V x O y Or SiO2.
7. The sensor device (1) according to any one of the preceding claims. The sensor device also has an additional hydroxide coating (9).
8. The sensor device (1) according to claim 7. The hydroxide coating (9) completely covers the entire sensor device (1) except for the second end region (4b).
9. The sensor device (1) according to any one of the preceding claims. The sensor device (1) described therein does not contain precious metals.
10. The sensor device (1) according to any one of the preceding claims. The covering part (7) is made of glass or polymer.
11. The sensor device (1) according to any one of the preceding claims. The sensor element (2) therein has an NTC sensor chip.
12. The sensor device (1) according to any one of the preceding claims. The sensor element (2) is based on the perovskite structure in the Y-Ca-Cr-Al-(Sn)-O system or the spinel structure in the Ni-Co-Mn-(Al)-(Fe)-(Cu)-(Zn)-(Ca)-(Zr)-(Ti)-(Mg)-O system.
13. The sensor device (1) according to any one of the preceding claims. The sensor device (1) is used at a temperature ≤400°C.
14. A method for manufacturing at least one sensor device (1) for measuring temperature, the method comprising the steps of: A) Provide at least one sensor element (2); B) At least two electrodes (3a, 3b) are formed on the surface of the sensor element (2); C) Provide at least two connecting elements (4), each having a first end region (4a) and a second end region (4b). D) Secure the first end region (4a) of the connecting element (4) to the sensor element (2); E) Constructing a covering portion (7), wherein the covering portion (7) completely covers the sensor element (2), the electrodes (3a, 3b) and at least the first end region (4a). F) Constructing a protective layer (8), wherein the protective layer (8) at least completely surrounds the area of the connecting element (4) that does not have the covering portion (7), except for the second end region (4b).
15. The method according to claim 14, The protective layer (8) is produced by anodizing, chemical coating or deposition from the vapor phase.
16. The method according to claim 14 or 15, The method also includes step G): annealing or hydrothermal treatment to form an additional hydroxide coating (9).
17. The method according to claim 16, The hydroxide coating (9) completely covers the entire sensor device (1) except for the second end region (4b).
18. The method according to any one of claims 14 to 17, Before fastening the connecting element (4) to the electrode (3a, 3b), the electrode (3a, 3b) is plasma cleaned.
19. The method according to any one of claims 14 to 18, Prior to step F), a protective varnish is applied to the second end region (4b) and the protective varnish is allowed to harden.
20. The method according to claim 19, The method further includes the following step: exposing the second end region (4b) of the connecting element (4) which is coated with the protective paint.
21. The method according to any one of claims 14 to 20, The first end region (4a) is flattened, and the connecting element (4) is connected to the sensor element (2) by means of ultrasonic welding, resistance welding or plasma welding of the flattened end region (4a), or the first end region (4a) is connected to the sensor element (2) by means of hard soldering.