Temperature sensor, sensor element and manufacturing method of temperature sensor
The temperature sensor design with multiple coatings addresses stability issues by matching thermal expansion coefficients and incorporating a buffer layer to absorb mechanical stress, enhancing durability and response time.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TDK ELECTRONICS AG
- Filing Date
- 2025-11-24
- Publication Date
- 2026-06-11
AI Technical Summary
Existing temperature sensors face issues with stability due to thermal expansion and contraction of different materials, leading to detachment, cracking, and mechanical stress.
A temperature sensor design with multiple coatings, where the first coating matches the thermal expansion coefficient of the thermosensitive body and wire, the second coating acts as a buffer to absorb mechanical stress, and the third coating provides additional stability, all connected to a mounting component.
Enhances mechanical strength and reduces the risk of detachment and cracking by synchronizing thermal expansion, absorbing mechanical stress, and providing shock absorption, resulting in improved durability and response time.
Smart Images
Figure EP2025084020_11062026_PF_FP_ABST
Abstract
Description
[0001] P2024 , 1148 WO N November 24 , 2025
[0002] 1
[0003] Description
[0004] Temperature sensor, sensor element and manufacturing method of temperature sensor
[0005] The present invention relates to a temperature sensor and a method of manufacturing the temperature sensor .
[0006] Temperature measurement is relevant in various technical fields . One such field may be temperature measurement on water pipes . However, the application of the present invention is not limited to this .
[0007] US 2021 / 0215549 Al describes a temperature sensor placed inside a tube with multiple covering layers for electrical insulation .
[0008] It is the task of the present invention to provide a temperature sensor with an improved stability .
[0009] This task can at least partly be achieved by a temperature sensor according to claim 1 . In the dependent claims , embodiments of features are provided which may provide additional advantages , and furthermore , describe a method of manufacturing the temperature sensor .
[0010] A temperature sensor is described which comprises a sensor element including a thermosensitive body, converting a temperature change of the thermosensitive body into a measurable change of an electrical quantity, for example the resistance . At least one wire is electrically connected to the thermosensitive body and is used for measurement of the electrical quantity in relation to the temperature of the P2024, 1148 WO N November 24, 2025
[0011] 2 thermosensitive body. The temperature sensor further comprises a mounting component for a mechanical and heat conducting connection of the temperature sensor to a component to be probed, for example a water pipe. Furthermore, the temperature sensor comprises at least two coatings, a first coating that encapsulates the thermosensitive body and the joint of the thermosensitive body with the wire, and a second coating that envelops the first coating and that is attached to the mounting component, are provided.
[0012] In the sensor element a solder joint is preferably used to connect the thermosensitive body with the wire.
[0013] The first coating encapsulates the thermosensitive body and the joint of the thermosensitive body with the wire.
[0014] For the first coating, a material is chosen that shows a similar coefficient of thermal expansion (GTE) as the thermosensitive body, the wire, and the electrical connection of the thermosensitive body with the wire. By doing so, the risk of detachment caused by the different thermal expansion or contraction of the different materials can be reduced.
[0015] The first coating preferably comprises or consists of an epoxy material with a coefficient of thermal expansion between 10xl0-6 / °C to 60xl0-6 / °C, for example 25xlO-6 / °C.
[0016] The first coating enhances the mechanical strength of the connection between the wire and the thermosensitive body.
[0017] The encapsulation with the first coating material of the joint of the wire with the thermosensitive body improves the P2024 , 1148 WO N November 24 , 2025
[0018] 3 protection of the wire from being torn of f from the thermosensitive body and the protection of the thermosensitive body from external forces , thus reducing the risk of cracking the sensor .
[0019] The second coating envelops the first coating from all sides . The second coating is attached to the mounting component by adhesive forces , connecting the arrangement comprising the sensor element and its first coating with the mounting component . The second coating improves the resistance against mechanical stress on the thermosensitive body induced by the di f ferent thermal expansions of the di f ferent materials of the thermosensitive body, the wire , the coatings , and the mounting component . The second coating has an elastic modulus lower than the elastic modulus of the first coating . Accordingly, even i f the temperature sensor is repeatedly exposed to rising and falling temperatures , and the di f ferent parts of the temperature sensor are expanded or contracted, the second coating easily elastically deforms to function as a buf fer with respect to expansion and contraction . As a result , the risk of cracking the thermosensitive body by thermomechanical stress can be reduced .
[0020] Further, the second coating that envelops the first coating works as a shock absorber by reducing external vibrations the sensor element experiences during the intended operation of the component to be probed . This also reduces the risk of cracking the sensor and, in combination with a first coating, protects the wire from tearing of f from the thermosensitive body . P2024 , 1148 WO N November 24 , 2025
[0021] 4
[0022] The second coating preferably consists of or comprises a silicon material with a low Shore hardness in the range of Shore A 50 to Shore A 90 , for example Shore A 80 .
[0023] In a temperature sensor, by applying the first coating and the second coating in the presented order, with the first coating being enveloped by the second coating, the two coatings show synergetic ef fects . This combination of the two coatings , with the first coating encapsulating the j oint of the wire with the thermosensitive body, and the second coating enveloping the first coating, achieves the enhanced resistance against thermomechanical stress , mechanical stress , and vibration .
[0024] According to an embodiment , the temperature sensor further comprises a third coating, enveloping the second coating . I f the temperature sensor comprises a third coating, the second coating will no longer be connected to the mounting component . Instead, the third coating will be attached to the mounting component via adhesive forces . The third coating provides further mechanical strength and stability to the sensor element and is used for a more robust connection between the arrangement comprising the sensor element and the mounting component .
[0025] For the third coating, a material is chosen that shows a similar coef ficient of thermal expansion ( GTE ) as the mounting component . By doing so , the risk of detachment caused by the di f ferent thermal expansion or contraction of the two materials can be reduced . P2024 , 1148 WO N November 24 , 2025
[0026] 5
[0027] The third coating preferably comprises or consists of an epoxy material with a coef ficient of thermal expansion between 10xl 0-6 / ° C to 60xl 0-6 / ° C, for example 25xl O-6 / ° C .
[0028] According to an embodiment , the third and the first coating are of the same material .
[0029] According to an embodiment , the third coating can be a potting .
[0030] According to an embodiment , the temperature sensor may further comprise additional coatings . In this case , the outermost coating of the arrangement comprising the sensor element will be attached to the mounting component .
[0031] According to an embodiment , the mounting component comprises or consists of a metal . The mounting component may be a metal ring tongue , enabling a simple and removable connection of the temperature sensor to the component to be probed . As example for such a simple connection, the ring of the ring tongue is mounted on the winding of a screw, that is then screwed into the component to be probed . Like this , the ring tongue is clamped between the component to be probed and the head of the screw . The clamping mechanism ensures a tight fit of the ring tongue and a constant contact to the component to be probed . This leads to fast response times of the temperature sensor and a good resistance against vibration .
[0032] The manufacturing method of the temperature sensor includes a first step of forming a first coating that encapsulates the thermosensitive body and the j oint of the thermosensitive body with the wire . Preferably, this step is done by dipping the sensor element into a solution of first coating material . P2024 , 1148 WO N November 24 , 2025
[0033] 6
[0034] Depending on the speed of removing the sensor from the solution and an option to vibrate the sensor element during the removal and the hardening process , the thickness of the first coating can be varied . A second step that takes part after the first coating has hardened comprises forming a second coating that envelops the first coating . The second coating is applied by dipping the sensor element with the hardened first coating into a solution of second coating material . The thickness of the second coating can be varied in the same way as in the first step .
[0035] The second coating is brought in mechanical contact with the mounting component before it has hardened . Thus , the coating hardens directly on top of the mounting component , leading to adhesive forces between the coating and the mounting component that connect the arrangement comprising the sensor element with the mounting component .
[0036] The manufacturing method may further comprise a third step of forming a third coating that envelops the second coating and that may be used to increase the robustness of the connection of the arrangement comprising the sensor element to the mounting component . The third coating is applied by potting the third coating material on top of the mounting component and the sensor element , with its first and second coating hardened, thus connecting the arrangement comprising the sensor element with the mounting component . In the case of a third coating, the second coating will not be brought in mechanical contact with the mounting component .
[0037] Further advantageous embodiments may become apparent from the following exemplary embodiments described in connection with the figures . However, the invention is not limited to said P2024 , 1148 WO N November 24 , 2025
[0038] 7 exemplary embodiments . Further, said exemplary embodiments are depicted in figures showing schematic drawings . These schematic drawings are not true to scale , and absolute and relative dimensions can be depicted in a distorted manner . Accordingly, no absolute or relative dimensions can be taken from the schematic depictions unless otherwise indicated . Elements that are identical , similar or have the same ef fect are denoted by the same reference signs in the figures .
[0039] Figure 1 shows a cross-section of an embodiment of a temperature sensor . The embodiment comprises three coatings and a ring tongue as mounting component .
[0040] Figure 2A to 2D show a cross sectional view of the intermediate bodies of the temperature sensor according to the steps of a method for manufacturing a temperature sensor according to an embodiment . It also refers to an embodiment comprising three coatings and a ring tongue as mounting component . Figure 2A illustrates the sensor element before any coating is applied, figure 2B illustrates the sensor after applying the first coating, figure 2C illustrates the sensor after applying the second coating and figure 2D illustrates the sensor after applying the third coating and connecting the arrangement comprising the sensor element to the mounting component .
[0041] A temperature sensor 1 according to a preferred embodiment of the present invention is described below with reference to drawings .
[0042] As illustrated in figure 1 and 2A to 2D, the temperature sensor 1 comprises a thermosensitive body 100 that is connected to the wire 101 via an electrical connection 102 . P2024 , 1148 WO N November 24 , 2025
[0043] As the thermosensitive body 100 , for example an NTC- thermistor is preferably used . The NTC-thermistor is an abbreviation for a thermally sensitive resistor with negative temperature coef ficient . A change in temperature leads to a change in electrical resistance of the thermistor' s material , for example a metal oxide . This change can be measured, and the temperature change can be calculated . Other thermosensitive bodies 100 that convert a temperature change into a change of an electrical quantity can be used as well .
[0044] As it can be seen in figures 2A to 2D, the wires 101 are electrically connected 102 to the thermosensitive body 100 and are used for measurement of the electrical quantity in relation to the temperature of the thermosensitive body 100 .
[0045] As electrical connection 102 of the wire 101 to the thermosensitive body 100 , for example a solder j oint 102 is preferably used .
[0046] The thermosensitive body 100 , the part of the wire 101 adj acent to the solder j oint 102 , and the solder j oint 102 are encapsulated in the first coating 110 , as it can be seen in figures 1 and 2A to 2D . By means of said encapsulation with the first coating 110 , the mechanical strength of the j oint 102 between the thermosensitive body 100 and the wire 101 is enhanced .
[0047] In this example , the first coating 110 is made of an epoxy . The relatively hard material of the first coating 110 improves the protection of the wire 101 from being torn of f from the thermosensitive body 100 and improves the protection P2024, 1148 WO N November 24, 2025
[0048] 9 of the thermosensitive body 100 from external forces, reducing the risk of cracking the thermosensitive body 100.
[0049] As it can be seen in figure 1 and 2A to 2D, a second coating 111, made of a material with a lower elastic modulus than the first coating 110, envelops the first coating 110. As the present embodiment comprises a third coating 112, the second coating 111 is not attached to the mounting component 120.
[0050] In this example, the second coating 111 is made of a silicone material. The lower elastic modulus compared to the first coating 110 allows the second coating 111 to easily elastically deform so as to function as a buffer. This is of major interest, as the thermosensitive body 100, the wire 101, the coatings 110 to 112, and the mounting component 120 are made of different materials, each comprising a different coefficient of thermal expansion (GTE) . When encountering temperature changes, the materials will expand and contract to different extents, leading to thermomechanical stress that can be absorbed by the second coating 111. This leads to a reduction of the risk of cracking the thermosensitive body 100 due to thermomechanical stress.
[0051] A further advantage of the low elastic modulus of the second coating 111 are the shock absorbing characteristics. Thus, the external vibrations caused during the intended use of the component to be probed and experienced by the thermosensitive body 100 can be reduced by the second coating 111, resulting in a lower risk of cracking the thermosensitive body 100 and of tearing off the wires 101 from the thermosensitive body.
[0052] As it can be seen in figure 1 and 2A to 2D, the embodiment of the sensor 1 further comprises a third coating 112. This P2024 , 1148 WO N November 24 , 2025
[0053] 10 coating envelops the second coating 111 and is attached to the mounting component 120 via adhesive forces . The third coating 112 provides additional mechanical strength to the arrangement comprising the sensor element 10 and increases the robustness of the connection of the arrangement comprising the sensor element 10 to the mounting component 120 .
[0054] In this example , the third coating 112 is made of an epoxy . By choosing a material with a GTE close to the GTE of the mounting component 120 , the risk of a detachment of the third coating 112 from the mounting component 120 , caused by the di f ferent expansion and contraction of the mounting components 120 material and the third coatings 112 material during temperature changes , can be minimi zed .
[0055] As the mounting component 120 , for example a metal ring tongue is preferably used . The ring tongue allows for an easy connection to the component to be probed . The form of the mounting component 120 can be freely adapted to the requirements of the intended use of the component to be probed . The metal has a GTE close to the GTE of the epoxy of the third coating 112 .
[0056] The figures 2A to 2D illustrate the intermediate bodies of the temperature sensor 1 during the manufacturing process .
[0057] In figure 2A, a cross sectional view of the sensor element 10 can be seen, before the manufacturing process starts . The wires 101 are electrically connected 102 to the thermosensitive body 100 . P2024 , 1148 WO N November 24 , 2025
[0058] 11
[0059] During the first manufacturing step, the sensor element 10 is dipped into a solution of the first coating 110 material . After removing the sensor element 10 from the solution, the first coating 110 is hardened, resulting in the first intermediate body, as illustrated in figure 2B .
[0060] Figure 2B shows a cross sectional view of the first intermediate body . The sensor element 10 , comprising the thermosensitive body 100 , the wires 101 and their connection 102 , is enveloped by the first coating 110 . The first coating 110 forms a small capsule around the thermosensitive body 100 and the connection 102 to the wires 102 , covering the thermosensitive body 100 , the connection 102 to the wires 101 and a small part of the wires 101 close to the connection .
[0061] During the second manufacturing step, the first intermediate body, as illustrated in figure 2B is dipped into a solution of second coating 111 material . After removing it from the solution, the second coating 111 is hardened, resulting in the second intermediate body, as illustrated in figure 2C .
[0062] Figure 2C shows a cross sectional view of the second intermediate body, the first coating 110 is further enveloped by the second coating 111 . The second coating 111 surrounds the first coating 110 from all sides .
[0063] During the third manufacturing step, the second intermediate body is placed close to the surface of a mounting component 120 , and the third coating 112 is applied via potting . The third coating 112 is hardened as well , resulting in the finished temperature sensor 1 , as illustrated in figure 2D . P2024 , 1148 WO N November 24 , 2025
[0064] - 12 -
[0065] Figure 2D shows a cross sectional view of the finished temperature sensor 1 . The third coating 112 envelops the second coating 111 . The third coating 112 is attached to the mounting component 120 via adhesive forces , resulting from its hardening process on top of the mounting component .
[0066] P2024 , 1148 WO N November 24 , 2025
[0067] 13
[0068] List of reference signs
[0069] 1 Temperature sensor
[0070] 10 Sensor element 100 Thermosensitive body
[0071] 101 Wire
[0072] 102 Electrical connection
[0073] 110 First coating
[0074] 111 Second coating 112 Third coating
[0075] 120 Mounting component
Claims
P2024, 1148 WO N November 24, 2025- 14 -Claims (We claim)1. A temperature sensor (1) , comprising a sensor element (10) , including a thermosensitive body (100) converting a temperature change of the thermosensitive body (100) into a measurable change of an electrical quantity, and at least one wire (101) that is electrically connected to the thermosensitive body (100) , a mounting component (120) for the mechanical and heat conducting connection of the temperature sensor (1) to a component to be probed, and at least two coatings, wherein the first coating (110) encapsulates the thermosensitive body (100) and an electrical connection (102) of the thermosensitive body (100) with the wire (101) , and wherein the second coating (111) envelops the first coating (110) and is attached to the mounting component (120) .
2. A temperature sensor (1) according to the previous claim, wherein the first coating (110) provides mechanical strength to said connection (102) of the wire (101) and the thermosensitive body (100) and protects the wire (101) from tearing off from the thermosensitive body (100) .
3. A temperature sensor (1) according to any of the previous claims, wherein the second coating (111) provides protection against mechanical stress on the thermosensitive body (100) , induced by the different thermal expansions of the different parts.P2024, 1148 WO N November 24, 2025154. A temperature sensor (1) according to any of the previous claims, wherein the second coating (111) provides protection against mechanical stress on the thermosensitive body (100) , induced by vibrations caused during the intended use of the component to be probed.
5. A temperature sensor (1) according to any of the previous claims, wherein the second coating (111) comprises an elastic silicone material with a Shore hardness of Shore A 50 to Shore A 90.
6. A temperature sensor (1) according to any of the previous claims, wherein the temperature sensor (1) further comprises a third coating (112) that envelops the second coating (111) , the third coating (112) being attached to the mounting component (120) instead of the second coating (111) and improving the robustness of the connection of the sensor element (10) on the mounting component (120) .
7. A temperature sensor (1) according to the previous claim, wherein the third coating (120) comprises an epoxy material with a coefficient of thermal expansion between 10xl0-6 / °C to 60xl0-6 / °C.
8. A temperature sensor (1) according to claim 6 or claim 7, wherein the material of the first coating (110) and the third coating (112) is the same.P2024, 1148 WO N November 24, 2025169. A temperature sensor (1) according to any of the previous claims, wherein the mounting component (120) comprises a metal.
10. A temperature sensor (1) according to the previous claim, wherein the mounting component (120) is a metal ring tongue.
11. A temperature sensor (1) according to any of the previous claims, wherein the thermosensitive body (100) is an NTC-chip.
12. A method of manufacturing a temperature sensor (1) according to any one of claims 1 to 11, comprising a first step of applying the first coating (110) that encapsulates the thermosensitive body (100) and the connection (102) of the thermosensitive body (100) and the wire (101) , and a second step of applying the second coating (111) that envelops the first coating (110) and that is attached to the mounting component (120) .
13. A method of manufacturing a temperature sensor (1) according to any one of claims 1 to 11, comprising a first step of applying the first coating (110) that encapsulates the thermosensitive body (100) and the connection (102) of the thermosensitive body (100) and the wire (101) , a second step of applying the second coating (111) that envelops the first coating (110) , and a third step of applying a third coating (112) that envelops the second coating (111) and that is attached to the mounting component (120) .