Temperature sensor with encapsulation and manufacturing method

Abstract

The present disclosure refers to a temperature sensor with encapsulation and to a method of manufacturing a temperature sensor (1), comprising the steps: providing the temperature sensor (1) comprising the thermistor element (2) and two electrical lead elements (3,6) connected to the thermistor element (2), arranging the sensor head in a transfer mold, encapsulating the sensor head by transfer molding.

Description

[0001] P2024 , 1198 WO N October 30 , 2025

[0002] 1

[0003] Description

[0004] Temperature sensor with encapsulation and manufacturing method

[0005] The present invention refers to a temperature sensor with encapsulation and a corresponding manufacturing or encapsulation method .

[0006] In existing processes for encapsulating NTC temperature sensors , the encapsulation process is performed by dipping the head of the sensor into coating material .

[0007] In other words , the coating is obtained by a dip coating process .

[0008] The dip coating method disadvantageously causes the encapsulation geometry to be unstable , wherein the dimensions of the encapsulation may have a wide tolerance range .

[0009] The manufacturing of precisely defined encapsulation shapes , surfaces , body structures or surface structures is not possible .

[0010] Due to varying wall thicknesses of the encapsulation, the resistance of the encapsulation against environmental impacts , mechanical impacts , humidity, voltage breakthrough, etc . , may be unstable .

[0011] The invention according to the present disclosure solves at least partly the deficiencies of the state-of-the-art technical solutions . P2024 , 1198 WO N October 30 , 2025

[0012] 2

[0013] The method of manufacturing a temperature sensor and the temperature sensor according to the invention is defined by the claims .

[0014] A method of manufacturing a temperature sensor according to the invention comprises at least the following steps :

[0015] In a step, the temperature sensor is provided . The temperature sensor comprises the thermistor element and two electrical lead elements connected to the thermistor element .

[0016] In another step, the sensor head is arranged in a trans fer mold .

[0017] The sensor head is a head part of the sensor which comprises at least the thermistor element . Besides , the sensor head may also comprise portions of the lead elements adj acent to the thermistor element .

[0018] In embodiments , the sensor head may also comprise the whole lead elements . Further outer lead elements may be foreseen to contact the lead elements of the sensor head electrically .

[0019] In another step, the sensor head, which is placed in the mold, is encapsulated by forming an encapsulation by trans fer molding in a molding step .

[0020] In other words , during a molding step, the sensor head is encapsulated by performing trans fer molding .

[0021] A trans fer molding process is similar to a compression molding process . However, in contrast to j ust pressing the molding material between two casting molds , during trans fer P2024 , 1198 WO N October 30 , 2025

[0022] 3 molding, the molding material is preferably inj ected into the mold cavity by means of pistons via distribution channels , where it hardens under heat and pressure .

[0023] Thus , the molding material which is the encapsulation material is advantageously subj ected to an enhanced temperature and pressure during manufacturing .

[0024] On the other hand, in conventional processes like dip coating, no enhanced temperatures and pressures ( enhanced compared to atmospheric properties ) are applied .

[0025] Thus , in the process of the invention, other encapsulation materials than in conventional dip coating processes can be used, which have advantageous properties regarding dielectric strength and robustness .

[0026] Furthermore , in conventional processes like dip coating, no molds are used . Thus , no flat , even, or uni form encapsulations can be manufactured .

[0027] On the other hand, the trans fer molding process advantageously allows to form encapsulations with even surfaces and a homogenous encapsulation thickness .

[0028] An encapsulation with a homogeneous thickness is particularly an encapsulation wherein the outer surface of the encapsulation is even without any bumps , protrusions , dents , or unevenness .

[0029] Thus , the produced sensor has advantageously a controllable dimension and form . P2024 , 1198 WO N October 30 , 2025

[0030] 4

[0031] Since the thickness of the encapsulation is homogeneous , also electric insulation performance , dielectric strength, and humidity resistance of the encapsulation improve .

[0032] Besides , also the protection against other environmental impacts like mechanical impacts , is improved .

[0033] Furthermore , by using molds , also impacts from the environment to the encapsulation material can be minimi zed .

[0034] The pressure applied in the mold during trans fer molding does further prevent the formation of unwanted air bubbles or cavities in the encapsulation .

[0035] By the prevention of air bubbles or cavities , the dielectric strength of the encapsulation can be enhanced and also the resistance against humidity can be enhanced .

[0036] According to an embodiment of the method, the step of providing the sensor comprises the following single steps .

[0037] In a step, the thermistor element is provided .

[0038] In another step, the two lead elements are provided .

[0039] In another step, the thermistor element is arranged between the two lead elements . In particular, the thermistor element may be provided as a flat chip which can easily be clamped between the lead elements .

[0040] Preferably, the thermistor element is arranged only between two tips of the two lead elements , in such a way that only P2024 , 1198 WO N October 30 , 2025

[0041] 5 the foremost end sections ( tips ) of the lead elements contact the thermistor element from only one side each .

[0042] By reducing the contact area between the thermistor element and the lead element , thermomechanical impacts to the thermistor during contacting and soldering processes between the lead elements and the thermistor can advantageously be reduced .

[0043] In another step, solder material is applied between the contact elements , preferably the tips of the contact elements , and the thermistor element by dip coating the sensor head into solder material .

[0044] Afterwards the solder material is cured by drying the material .

[0045] Preferably, the solder material is applied very accurately only between the tips of the lead elements and the thermistor .

[0046] According to an embodiment , the surface of the thermistor element is activated by plasma treatment before encapsulation .

[0047] By activating the surface , the surface roughness and surface area may be enhanced . Furthermore , chemical and / or physical adhesion properties of the surface may be enhanced .

[0048] Accordingly, by a timely advanced step of surface activation the adhesion of the encapsulation to the thermistor is advantageously improved . P2024 , 1198 WO N October 30 , 2025

[0049] 6

[0050] According to an embodiment , the lead elements are lead frames .

[0051] Lead frames have an advantageous high stability . Thus , the lead frame advantageously also works as a support structure for holding the sensor during the molding step .

[0052] Several sensors may be manufactured parallelly by the method according to the invention .

[0053] According to an embodiment , the lead frames of several sensors form a common support structure to hold the sensors during the molding step .

[0054] In other words , the lead frames of several sensors are connected to form the support structure .

[0055] In a following step, the sensors may be singulated by separating the lead frames from each other .

[0056] According to an embodiment , the lead elements are wires .

[0057] A wire has the advantage of higher flexibility compared to a lead frame .

[0058] On the other hand, the lead frame can directly work as a support structure , not only as an electrical connection element .

[0059] According to an embodiment , one or several wires may be held by a support structure during the molding step . P2024 , 1198 WO N October 30 , 2025

[0060] 7

[0061] The lead frame or the wire may comprise a bronze material , a phosphor bronze material , a di f ferent copper alloy material or a copper material as an electrically conductive material .

[0062] The lead frame or the wire may be additionally tin-plated for an advantageously enhanced corrosion resistance .

[0063] The lead frame thickness may be varied between 0 . 4 mm to 1 mm .

[0064] As already indicated above , at least according to an embodiment , the thermistor element may be clamped between the lead elements . In this case the lead elements may exert a clamping force on the thermistor element that is capable of holding the thermistor in place without further support . This may be advantageous , as the position of the thermistor element with respect to the lead elements can be defined clearly by precisely arranging the thermistor element between the lead elements . This allows that the position remains unchanged also during soldering or during the trans fer molding . This in turn may bring the advantage that the variance of position of the thermistor element in the trans fer molding is reduced leading to a more predictable or more homogeneous thickness of the cover . This embodiment is most preferred for the lead frame arrangement , i . e . it is preferred, that the lead frames clamp the thermistor element .

[0065] According to an embodiment , at least one of the lead elements may have a protrusion in the portion that contacts the lead element . Also , both lead elements may have a protrusion . However, it may be preferred in some embodiments that one lead element has a protrusion, while the other is flattened in the portion that contacts the lead element . For example , P2024 , 1198 WO N October 30 , 2025

[0066] 8 the protrusion may be arranged in the tip of the lead element .

[0067] A protrusion can be understood as it is understood in the field and is not limited otherwise . For example , the protrusion may be a part of the lead element protruding from it . In particular, the protrusion can be oriented towards the thermistor element . For example , the protrusion may focus a clamping force onto a smaller surface compared to a lead element without the protrusion . In order to do this , for example , the protrusion may have a smaller area at the side facing the thermistor element than at the side on which it is connected to the rest of the lead element . For example , the protrusion may be tip-shaped . According to another example the protrusion may be rounded, such a being semispherical or semielliptical .

[0068] The protrusion has the advantage that a clamping can be supported . In particular, by focusing the clamping force onto a reduced surface the clamping pressure may be increased . This has the advantage that friction caused by the clamping can be increased . Also , compared to two flattened contact areas of the lead elements , having at least one with a protrusion and thus a reduced contact area may reduce wobbling of the clamped thermistor element .

[0069] Also , the embodiment having the protrusion is particularly preferred for the lead- frame design . I . e . according to an embodiment it can be preferred that at least one lead frame has a protrusion . The above variations , embodiments and features regarding the protrusion may of course apply in this case . P2024, 1198 WO N October 30, 2025

[0070] 9

[0071] According to an embodiment, the thermistor element is a thermistor element with negative temperature coefficient (NTC) .

[0072] An NTC thermistor element has compared to a thermistor element with positive temperature coefficient (PTC) a comparatively small dimension.

[0073] Preferably, the diameter of a sensor head with an NTC thermistor element inside is not bigger than

[0074] 2.5 mm + / - 0.1 mm tolerance.

[0075] Thus, the usage of material can be minimized.

[0076] According to an embodiment, the portions of the lead elements and the thermistor element are encapsulated in one single molding step.

[0077] Thus, one uniform encapsulation is formed around the sensor head. The encapsulation is preferably configured as one single piece, which has advantageous dielectric strength and humidity density properties.

[0078] The thickness of the whole encapsulation may be constant or the encapsulation may be thicker around the thermistor in order to provide optimized protection.

[0079] According to an embodiment, transfer molding is performed at an elevated temperature of 170 °C or higher, more preferably at 180 °C or higher.

[0080] Such a high temperature can only be applied in a transfer molding procedure, wherein the molding material P2024 , 1198 WO N October 30 , 2025

[0081] - 10 -

[0082] ( encapsulation material ) is processed under high pressure . In a dip coating procedure such high temperatures are not feasible .

[0083] Advantageously, the high processing temperature during the trans fer molding step guarantees a complete or almost complete evaporation of all humidity (water ) in the encapsulation .

[0084] Thus , defects of the sensor because of humidity in the encapsulation can be prevented .

[0085] Further, by a decreased level of humidity in the encapsulation, also the dielectric strength of the encapsulation is improved .

[0086] According to an embodiment , the encapsulation comprises an epoxy resin material .

[0087] According to a more speci fic embodiment , the encapsulation comprises an epoxy resin material having a low electrical conductivity of not more or less than 100 pS / cm .

[0088] The selection of such a material in conventional dip coating processes is not feasible , because the high temperature and pressure of the trans fer molding process is required for processing such a material .

[0089] According to an embodiment , the encapsulation is applied evenly on the sensor head, preferably with a constant thickness as described before .

[0090] Because of the constant thickness of the encapsulation, because of the prevention of air bubbles or cavities or P2024, 1198 WO N October 30, 2025

[0091] 11 humidity in the encapsulation, and because of the usage of an epoxy resin material with a low electrical conductivity of not more or less than 100 pS / cm, the dielectric strength of the encapsulation can be advantageously improved.

[0092] According to an embodiment, a trace is printed into a surface of the encapsulation during the molding step. In other words, a trace or mark is formed into the surface of the encapsulation directly by the mold during the molding step.

[0093] The trace or mark may be a printed code or a number, e.g. a QR code, for an improved traceability of the sensor.

[0094] According to an embodiment, an inner coating is applied before the transfer molding. Applying such an inner coating layer may help to improve the protection of the thermistor element. In particular, the thermistor element may be better protected against influences from the surrounding during fabrication, mounting or measurement. For example, humidity resistance may be improved.

[0095] Also, the inner coating may improve the adhesion of the transfer molded encapsulation.

[0096] In particular, according to an embodiment, the inner coating may be applied after the soldering step.

[0097] The means for applying the inner coating is not limited. For example, dip-coating, spray-coating, injection-molding or also transfer molding may be used. Preferably, dip coating is used . P2024 , 1198 WO N October 30 , 2025

[0098] 12

[0099] According to an embodiment , the inner coating comprises or consist of a curable resin . For example , the curable resin may be provided in a liquid form or in solution . The liquid form may be preferred . For example , after the coating, a curing step can be performed . Such a step may be a heat treatment step or another curing step, such as irradiation . For example , the inner coating may comprise or consist of an epoxy resin . For example , the epoxy resin can be a diglycidyloxy-terminated perfluoropolyether .

[0100] According to an embodiment , the inner coating covers the thermistor element . According to a preferred embodiment , in addition to the thermistor element the inner coating also covers the portions of the lead elements next to the thermistor element .

[0101] The embodiments using an inner coating are particularly preferred for the embodiments having lead frames . For example , the lead frames with the thermistor element assembled between, is dipped into the liquid resin and then cured . Subsequently the trans fer molding is applied .

[0102] According to an embodiment the process steps of applying an inner coating can be carried out for several thermistor elements held by connected lead frames in parallel .

[0103] According to an embodiment , the inner coating is considerably thinner than the encapsulation . For example , a thickness of the inner coating may be below 6 pm, such as between 1 pm and 6 pm .

[0104] Further, the invention concerns a temperature sensor according to the claims . P2024 , 1198 WO N October 30 , 2025

[0105] - 13 -

[0106] All embodiments , and features or properties of the manufacturing method for manufacturing the temperature sensor may also apply to the temperature sensor ( as a product ) and vice versa .

[0107] The temperature sensor according to the invention comprises at least a thermistor element , two lead elements arranged at opposite sides of the thermistor element and connected to the thermistor element by solder, and an encapsulation with an even surface comprising an epoxy resin material and enveloping the thermistor element and adj acent portions of the lead elements .

[0108] In other words , the encapsulation envelops a sensor head comprising at least the thermistor element and adj acent portions of the lead elements or the whole lead elements .

[0109] According to an embodiment , due to its thickness , the chosen material and avoidance of air bubbles or cavities , the encapsulation has a high dielectric strength ( epoxy resin material of the encapsulation has a low electrical conductivity of less than 100 pS / cm) .

[0110] According to an embodiment , the encapsulation has a homogenous density with no air bubbles inside .

[0111] According to an embodiment , the thickness of the encapsulation amounts between 0 . 2 and 1 mm .

[0112] The epoxy resin material comprises at least an epoxy resin . P2024, 1198 WO N October 30, 2025

[0113] 14

[0114] In embodiments, the amount of epoxy resin in the encapsulation material may vary between 5 and 10 weight-%, preferably between 8 and 10 weight-%.

[0115] Additionally, the epoxy resin material may comprise further different resin materials.

[0116] According to an embodiment, the epoxy resin material comprises one or several of the following materials: epoxy resin, phenolic resin, silica, particularly vitreous silica, silicon dioxide, carbon black.

[0117] Preferably, the glass transition temperature of the epoxy resin material may be 100 °C or higher.

[0118] According to an embodiment, a surface of the encapsulation is flat and even.

[0119] According to an embodiment, the encapsulation has a homogenous thickness, which means that the thickness of the encapsulation between the thermistor element and the environment is set to a constant amount.

[0120] According to an embodiment, a trace or mark is printed into a surface of the encapsulation.

[0121] According to an embodiment, the trace is a QR-code, which allows a better tracing of the sensor.

[0122] The trace is good visible because of the advantageously flat and even surface of the encapsulation. P2024, 1198 WO N October 30, 2025

[0123] 15

[0124] According to an embodiment, only the tips of the lead elements are connected to the thermistor element.

[0125] According to an embodiment, the thermistor element is clamped between the two lead elements.

[0126] According to an embodiment, at least one lead element has a protrusion in the portion contacting the thermistor element. The explanations and examples regarding the protrusion addressed above may apply.

[0127] According to an embodiment, the encapsulation has a defined predetermined dimension and shape. The exact dimensions and the exact shape depend on the needs and specifications of a customer .

[0128] Depending on, e.g. the mounting conditions and the mounting location, the shape of the encapsulation may be varied as described below.

[0129] According to an embodiment, the encapsulation has a cuboid shape, e.g., a flat rectangular shape.

[0130] According to an alternative embodiment, the encapsulation has a cylindrical shape. The base area of the cylindrical shape may be a circle or an ellipse.

[0131] According to an alternative embodiment, the encapsulation has the shape of a cylinder segment.

[0132] According to an embodiment, an inner coating is arranged between the thermistor element and the encapsulation. Preferably, the inner coating is in direct contact with both P2024 , 1198 WO N October 30 , 2025

[0133] 16 the thermistor and the encapsulation . The above-discussed features or properties may apply .

[0134] In the following, example embodiments of the invention are further described by figures illustrating the embodiments .

[0135] The invention is not limited or restricted to the example embodiments .

[0136] The figures show as follows :

[0137] Figure 1 : shows a schematic view of a first step for producing an embodiment sensor, wherein a thermistor chip is clamped between lead elements .

[0138] Figure 2 : shows a schematic view o f a second step for producing an embodiment sensor, wherein the thermistor chip and the lead elements are connected by solder .

[0139] Figure 3 : shows a schematic view of a third step for producing an embodiment sensor, wherein the head of the sensor is encapsulated by a resin mold .

[0140] Figure 4 : shows a schematic view o f an embodiment arrangement , wherein several sensors are connected by lead frames which form a support structure .

[0141] Figures 5 , 6 , 7 : show schematics view of an embodiment of the temperature sensor, wherein the encapsulation of the thermistor has an essentially cylindrical shape and the lead elements are lead frames . P2024 , 1198 WO N October 30 , 2025

[0142] 17

[0143] Figures 8 , 9 , 10 : show schematic views of an embodiment of the temperature sensor, wherein the encapsulation of the thermistor has an essentially cuboid shape and the lead elements are lead frames .

[0144] Figures 11 , 12 , 13 : show schematic views of an embodiment of the temperature sensor, wherein the encapsulation of the thermistor has an essentially hal f-round shape and the lead elements are lead frames .

[0145] Figure 14 : shows a schematic view of an embodiment of the temperature sensor, wherein the encapsulation of the thermistor has an essentially cylindrical shape and the lead elements are wires .

[0146] Figure 15 : shows a perspective view of the embodiment of the temperature sensor of figure 8 .

[0147] Figure 16 shows an additional intermediate step in producing another embodiment of a temperature sensor .

[0148] Figure 17 shows a schematic cross section of a further embodiment of a temperature sensor .

[0149] Firstly, in the figures 1 to 3 , a process of manufacturing a temperature sensor 1 is illustrated .

[0150] In figure 1 , a first step is shown . In the first step, a thermistor chip 2 , which is a thermistor element in a flat circular or rectangular shape , and two lead frames 3 are provided . P2024 , 1198 WO N October 30 , 2025

[0151] 18

[0152] The thermistor chip 2 comprises a thermistor ceramic material . The thermistor ceramic material comprises a ceramic with a negative or a positive temperature coef ficient (NTC ceramic, PTC ceramic ) .

[0153] Two essentially identical lead frames 3 may be used .

[0154] The thermistor chip 2 is pushed between the foremost tips of the two symmetrically arranged lead frames 3 and clamped therebetween .

[0155] In order to assist the clamping one of the lead frames 3 ( left in the depiction) has a protrusion 7 . The protrusion 7 protrudes from the tip of that lead frame in the direction of the thermistor chip 2 . The protrusion has a mainly semicircular cross-section . It may have a semispherical or semielliptical shape three-dimensional shape .

[0156] The protrusion has the advantage that it focusses the clamping force of the lead frame 3 on a smaller area . This may help to increase the friction .

[0157] The other lead frame that has not the protrusion is flattened in the present exemplary embodiment . This brings the advantage that the thermistor chip 2 is stabili zed form one side by a flattened surface while from the other side the small surface area of the protrusion presses on the chip . Thus , wobbling of the thermistor chip 2 may be reduced .

[0158] This allows for a more precise positioning of the thermistor chip 2 . Also , additional means for holding the chip in place in later process steps may be unnecessary . In addition, the P2024 , 1198 WO N October 30 , 2025

[0159] - 19 - precise positioning may help to reali ze a defined or in particular a homogeneous coating .

[0160] In a second step, the whole arrangement is dipped into solder material S in order to connect the chip 2 and the lead frames 3 mechanically and electrically .

[0161] The solder material S may be any suitable material .

[0162] The solder material S may be applied precisely or superfluous solder material S may be removed in an automated process , in such a way that the solder material S is only applied between the thermistor chip 2 and the tips of the lead frames 3 .

[0163] The solder material S is cured to form a solid solder connection, as illustrated in figure 2 .

[0164] During the soldering process and the following encapsulation steps , the sensor, particularly the lead frame , may be supported by a support structure , as also illustrated in figure 4 .

[0165] In an embodiment , the lead frames of several sensor are attached together to form the support structure .

[0166] In the encapsulation steps , the sensor head comprising the thermistor chip 2 and the adj acent portions of the lead frames 3 are arranged in a mold for trans fer molding together with the molding material .

[0167] The molding material is an epoxy resin material with electrically insulating properties , which is preferably a good heat conductor . P2024, 1198 WO N October 30, 2025

[0168] - 20 -

[0169] The mold for transfer molding particularly comprises two molding tools which are pressed together to form the mold and to shape the sensor encapsulation.

[0170] The encapsulation is formed precisely by the transfer molding process .

[0171] During the transfer molding process, the molding resin is subjected to high pressures and temperatures. Thus, a different resin material can be used than in conventional dip coating processes .

[0172] A preferred molding temperature lies between 170 °C and 180 °C.

[0173] The clamp force of the molding tools lies preferably between 20 and 40 tons. The transfer pressure during transfer molding preferably lies between 50 and 70 kg / cm2.

[0174] During the transfer molding process, the shape, and the surface of the encapsulation 4 covering the sensor head is formed according to the predetermined shape of the mold.

[0175] A highly even and smooth surface is obtained.

[0176] After molding, the encapsulation may be cured for 3 to 5 hours at an elevated temperature between 170 °C and 180 °C.

[0177] Since the surface is very even and smooth, it is even possible to create filigree structures on the surface, directly during the molding process.

[0178] In the embodiment example, a mark 5 on the surface of the encapsulation 4 is created. P2024 , 1198 WO N October 30 , 2025

[0179] - 21 -

[0180] The mark or trace may be a brand logo , a product designation or number, a tracing number, a code , a QR-code etc .

[0181] By forming the trace or code 5 on the surface , the single sensor 1 may be (better ) traceable / recogni zable .

[0182] The encapsulation 4 may cover a portion of the lead frame in the sensor head or the whole lead frame 3 .

[0183] A variation of the previous process and an additional embodiment of a temperature sensor 1 is discussed with respect to Figures 16 and 17 .

[0184] Figure 16 depicts an intermediate process step that can optionally be applied after the process step discussed with respect to Figure 2 , i . e . after the soldering and before the step of forming the encapsulation 4 by the trans fer molding .

[0185] In particular, after soldering the so far fabricated temperature sensor 1 is provided with an inner coating 8 . The inner coating 8 is formed by dip coating the temperature sensor 1 into the liquid form of an epoxy resin . The resin in the present case is a diglycidyloxy-terminated perfluoropolyether . Subsequently the resin is cured via heating .

[0186] The inner coating 8 is applied such that it at least covers the thermistor chip 2 . Preferably, and as depicted the inner coating may extend onto the lead frames 3 , covering portions of the lead frames 3 next to the thermistor chip 2 . P2024 , 1198 WO N October 30 , 2025

[0187] 22

[0188] As depicted, the inner coating may be comparatively thin . In particular it , can be thinner than the subsequently applied encapsulation 4 . For example , the inner coating 8 can have a thickness of 1 to 6 pm .

[0189] In the present embodiment , the inner coating 8 is depicted to individually cover each lead frame 3 with a gap in the inner coating 8 in the space of the lead frames below the thermistor chip 2 . This is not necessarily the case in each reali zed embodiment . The described space may also be closed by the inner coating 8 .

[0190] After applying the inner coating 8 , in a next step / in the next steps , the encapsulation 4 can be reali zed as described above .

[0191] In Figure 17 an embodiment of a finished temperature sensor 1 is depicted in schematic cross section . The present embodiment also has the inner coating 8 . Otherwise , it may be identical to the temperature sensor 1 discussed with respect to Figure 3 .

[0192] The encapsulation 4 fully encloses the inner coating 8 .

[0193] The inventors found out that reali zing an inner coating 8 may additionally improve robustness performance against moisture or humidity ingress .

[0194] Figure 4 shows a support structure 10 for supporting and carrying the sensors during the manufacturing process .

[0195] Additionally, or alternatively, several sensors may be connected by their lead frames to form a support structure . P2024, 1198 WO N October 30, 2025

[0196] - 23 -

[0197] After the encapsulation process, the sensors may be singulated by removing the support structure or by dividing the connections between the single lead frames.

[0198] In figures 5 to 13, several views of embodiments of the completed temperature sensor are shown.

[0199] In figures 5, 6, and 7, the encapsulation of the thermistor chip 2 has an essentially cylindrical shape.

[0200] On top in figure 5, a view from above is shown, below in figure 6, a front view is shown. On the right in figure 7, a side view is shown.

[0201] The further shape of the encapsulation 4 is adapted to the shape of the lead frames 3. The lead frames 3 in the example embodiment are bent accordingly, so that the two lead frames 3 get narrower in the region of the thermistor chip 2, in order to clamp the chip 2.

[0202] The shape of the encapsulation 4 is preferably adapted accordingly to facilitate the assembly or fixation of the sensor 1 at the place of application.

[0203] Furthermore, the structure, shape and surface of the encapsulation may be adapted and modified in the molding process accordingly to facilitate assembly.

[0204] In figures 8, 9, and 10, the encapsulation of the thermistor chip 2 has an essentially cuboid shape.

[0205] More particularly, the shape is essentially cuboid with rectangular side surfaces. P2024, 1198 WO N October 30, 2025

[0206] - 24 -

[0207] The surfaces of the essentially cuboid body may be slightly inclined with an edge in the center of the surface or may be flat.

[0208] On top in figure 8, a view from above is shown, below in figure 9, a front view is shown. On the right in figure 10, a side view is shown.

[0209] All embodiments may be structured axially symmetrically when viewed from anyone of the six spatial directions.

[0210] In figures 11, 12, and 13, the encapsulation of the thermistor chip 2 has an essentially half-round shape of a cylinder segment. The shape may also resemble or correspond to a prismatic shape with a half-round, half-rectangular base area.

[0211] More particularly, the shape is essentially half-cuboid with rectangular side surfaces and half-cylindrical.

[0212] The surfaces of the essentially cuboid body-part may be slightly inclined with an edge in the center of the surface or may be flat.

[0213] Thus, the embodiment in figures 11, 12, 13 may be a combination of the embodiments in the figures before.

[0214] On top in figure 11, a view from above is shown, below in figure 12, a front view is shown. On the right in figure 13, a side view is shown. P2024, 1198 WO N October 30, 2025

[0215] 25

[0216] Figures 14 and 15 show a further embodiment of the temperature sensor 1 which comprises wires 6 as lead elements instead of lead frames 3.

[0217] The wires may be more flexible compared to the lead frames.

[0218] A portion of the wires 6 may be encapsulated by the encapsulation 4.

[0219] The manufacturing and encapsulation process otherwise resembles the process with lead frames 3.

[0220] In the example, the encapsulation covering the thermistor chip 2 has a cylindrical shape. However, as also described before, the encapsulation may have any suitable geometrical shape, e.g., prismatic, cuboid, cylindrical, half-cylindrical, spherical, etc.

[0221] Alternatively, the thermistor of the present invention may be a PTC thermistor.

[0222] The thermistor may have a monolithic ceramic structure or a structure comprising several or multiple layers.

[0223] The thermistor may also comprise electrodes or electrode layers for electrical connection.

[0224] The electrode layers may comprise suitable metallic or electrically conductive polymer materials.

[0225] The encapsulation may also be referred to as casing, covering, case, enveloping, housing, etc. P2024 , 1198 WO N October 30 , 2025

[0226] - 26 -

[0227] Reference signs

[0228] 1 sensor

[0229] 2 thermistor chip 3 lead frame

[0230] 4 encapsulation

[0231] 5 trace

[0232] 6 wire

[0233] 7 protrusion 8 inner coating

[0234] 10 support structure

[0235] S solder material

Claims

P2024, 1198 WO N October 30, 2025- 27 -Claims (We claim)1. Method of manufacturing a temperature sensor (1) , comprising the steps:- providing the temperature sensor (1) comprising the thermistor element (2) and two electrical lead elements (3, 6) connected to the thermistor element (2) ,- arranging the sensor head comprising the thermistor element (2) and at least portions of the lead elements (3, 6) adjacent to the thermistor element (2) in a transfer mold,- encapsulating the sensor head by forming an encapsulation (4) by transfer molding in a molding step.

2. Method according to claim 1, wherein providing the sensor (1) comprises the following steps:- providing the thermistor element (2) ,- providing two lead elements (3, 6) ,- arranging the thermistor element (2) only between two tips of the two lead elements (3, 6) ,- applying solder material (S) between the tips and the thermistor element (2) by dip coating,- curing of the solder material (S) .

3. Method according to any of claims 1 or 2, wherein the surface of the thermistor element (2) is activated by plasma treatment before encapsulation.

4. Method according to any of claims 1 to 3, wherein the lead elements are lead frames (3) .

5. Method according to claim 4, wherein the lead frames (3) of several sensors (1) form a support structure (10) to hold the sensors during the molding step, wherein the sensors (1)P2024, 1198 WO N October 30, 2025- 28 - are singulated by separating the lead frames (3) in a following step.

6. Method according to any of claims 1 to 3, wherein the lead elements are wires (6) .

7. Method according to claim 6, wherein one or several wires (6) are held by a support structure during the molding step.

8. Method according to any of claims 1 to 7, wherein the thermistor element (2) is a thermistor element with negative temperature coefficient.

9. Method according to any of claims 1 to 8, wherein the portions of the lead elements (3) and the thermistor element (2) are encapsulated in one single molding step.

10. Method according to any of claims 1 to 9, wherein the transfer molding is performed at an elevated temperature of 170 °C or higher.

11. Method according to any of claims 1 to 10, wherein the encapsulation (4) comprises an epoxy resin material.

12. Method according to claim 11, wherein the epoxy resin material comprises between 5 and 10 weight-% epoxy resin.

13. Method according to claim 11 or 12, wherein the encapsulation (4) comprises an epoxy resin material having a low electrical conductivity of not more, or less than 100 pS / cm.P2024, 1198 WO N October 30, 20252914. Method according to any of claims 1 to 13, wherein the encapsulation (4) is applied evenly on the sensor head.

15. Method according to any of claims 1 to 14, wherein a trace (5) is printed into a surface of the encapsulation (4) during the molding step.

16. Method according to any of the preceding claims, wherein at least one lead element (3, 6) has a protrusion (7) facing the thermistor element (2) .

17. Method according to any of the preceding claims, wherein an inner coating (8) covering at least the thermistor element (2) is realized before forming the encapsulation (4) .

18. Method according to the preceding claim, wherein the inner coating (8) extends to the portion of the lead elements (3, 6) neighboring the thermistor element (2) .

19. Method according to the preceding claim, wherein the inner coating (8) is formed via dip coating the soldered thermistor element (2) into an epoxy resin in its liquid or dissolved form and subsequently curing the resin.

20. Temperature sensor (1) comprising- a thermistor element (2) ,- two lead elements (3, 6) arranged at opposite sides of the thermistor element (2) and connected to the thermistor element by solder ( S ) ,- an encapsulation (4) with an even surface comprising an epoxy resin material and enveloping the thermistor element (2) and adjacent portions of the lead elements (3, 6) .P2024, 1198 WO N October 30, 20253021. The temperature sensor (1) according to the preceding claim, wherein the epoxy resin material has a low electrical conductivity of not more, or less than 100 pS / cm.

22. The temperature sensor (1) according to claim 20 or 21, wherein the encapsulation (4) has a homogenous density with no air bubbles inside.

23. The temperature sensor (1) according to any of claims 20 to 22, wherein a trace (5) is printed into a surface of the encapsulation .

24. The temperature sensor (1) according to claim 23, wherein the trace (5) is a QR-code.

25. The temperature sensor (1) according to any of claims 20 to 24, wherein only the tips of the lead elements (3) are connected to the thermistor element (2) .

26. The temperature sensor (1) according to any of claims 20 to 25, wherein the encapsulation (4) has a cuboid shape.

27. The temperature sensor (1) according to any of claims 20 to 26, wherein the encapsulation (4) has a cylindrical shape.

28. The temperature sensor (1) according to any of claims 20 to 27, wherein the encapsulation (4) has a homogenous thickness .

29. The temperature sensor (1) according to any of claims 20 to 28, wherein the encapsulation (4) has the shape of a cylinder segment.P2024, 1198 WO N October 30, 2025- 31 -30. The temperature sensor (1) according to any of claims 20 to 29, wherein at least one lead element (3, 6) has a protrusion (7) facing the thermistor element (2) .

31. The temperature sensor (1) according to any of claims 20 to 30, wherein an inner coating (8) is arranged between thermistor element (2) and encapsulation (4) .

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