PTC heater element, electric heater device, and method of using PTC heater element

Abstract

To relate to a heater element, and in particular to a PTC heater element.SOLUTION: A PTC heater element (1) for an electric heater device includes at least one PTC element (2) in which at least one electrode is formed on the surface of the PTC element (2) for electrical contact of the PTC element (2), at least one further contact (4) for electrical connection of the electrodes of the PTC element (2), and at least one carrier layer (5) formed to be electrically insulating, and the thickness (d) of the PTC element (2)≤500 μm and the height (H) of the PTC heater element (1) is between 500 μm and 2500 μm.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a heater element, in particular a PTC heater element. The present invention further relates to an electric heater device comprising a PTC heater element. The present invention further relates to a method of using a PTC heater element in a motor vehicle, for example an electric vehicle.

Background Art

[0002] A heater resistor equipped with a PTC ("Positive Temperature Coefficient": thermistor) heater element has the advantage that its power consumption is automatically limited when a certain temperature is reached due to its characteristic of temperature-dependent resistance. This characteristic serves not only as a safety function to avoid overloading the heater resistor, but also simplifies the drive control due to the self-regulating effect.

[0003] Use in electric vehicles suggests operating the resistor directly with a high-voltage battery (200 - 400 V, in some cases 800 V). For this reason, it is necessary to design the insulation strength accordingly. Usually, the PTC element is electrically contacted by conductor paths on two opposing surfaces. The conductor paths are carried by a substrate and decouple the heat generated on the opposite side.

[0004] The decouplable heat output strongly depends on the heat path through the above-described layer structure. Heat must reach the extraction surface or decoupling surface (Auskopplungsflaeche) from the point of generation (PTC) through the contact and through the substrate. Here, the thermal and electrical considerations for optimizing the heater element are often exposed to conflicting discussions. That is, the prior art design is a product of a compromise between output density, thermal agility, insulation ability or robustness, and reliability.

[0005] For example, the fact that the manufacturer of the PTC element and the manufacturer of the heater element are not the same means that the PTC element must meet certain requirements in terms of geometric tolerances, transportation and handling during the assembly process, etc. That is, within a reasonable labor frame, it cannot fall below a certain minimum thickness of the PTC element.

[0006] Directly connecting the PTC element to the (metal) heat sink is also thermally optimal. However, in a high-voltage system (230V - 00V), since electrical insulation is required, a non-conductive barrier is needed to sufficiently separate the system voltage from the radiator. Furthermore, it is necessary to maintain different inter-pole space distances and creepage distances (usually 4mm in the high-voltage heaters of electric vehicles), which can only be achieved by using insulating materials.

[0007] When Joule heat is generated by energization, the PTC element itself functions as a heat source. However, this does not occur uniformly within the material, and depending on the geometric shape and the possibility of material non-uniformity, a temperature gradient may occur due to the electric field distribution within the component. Starting from the hot spot, heat must first reach the surface of the element before it can be further transported. Since the thermal conductivity of the PTC ceramic is relatively low (usually, ~5W / mK), this may occur very slowly and gradually.

[0008] Document EP3101999A1 describes a PTC heating element for an electric heating device in a vehicle. This PTC heating element is electrically insulated on the outside by an improved method, and the need for appropriate heat transfer from the PTC element to the heat dissipation surface through the electrical insulation layer is also considered. For this purpose, an electrical insulation layer is provided that consists of an outer surface in contact with at least one conductive track through which the PTC element is energized, a foil, and an electrically insulating bulk body with good thermal conductivity coated thereon.

[0009] Document US2017 / 0223776A1 describes an electric heating device having at least one PTC electric heating element and radiation fins (Strahlungsrippen) arranged on the outer surface of the PTC electric heating element. The surface on the radiation fins not in contact with the PTC electric heater element is not charged. An insulating layer is provided between the conductor path and the heat dissipation fins.

[0010] Also, document DE112017006124T5 describes a heater device having an insulating layer between the conductor path and the cooling fins. This electric heater includes a plurality of PTC elements, heat dissipation fins that dissipate heat transferred from the PTC elements, a resin plate that insulates the electrode plate, and compression springs that press the laminate from both sides in the stacking direction.

[0011] Document EP1182908B1 describes a PTC heater device having at least one PTC element and two contact plates in contact with the PTC element. In order to connect the surface of the PTC element to the contact plate, a metal foil coated with an adhesive on both sides is provided. The contact plates are not insulated.

[0012] The link https: / / air-lab.de / index.html explains a heater block that makes direct contact with aluminum cooling fins for optimal heat extraction (Waermeauskopplung). In this case, electrical insulation is not performed.

Summary of the Invention

[0013] The object of the present invention is to provide a PTC heater element and an electric heating device that solve the above problems.

[0014] This object is solved by a PTC heater element, an electric heating device according to the independent claims, and the use of the PTC heater element.

[0015] According to one aspect, a PTC heater element is described. The PTC heater element is designed to be incorporated into an electric heater device, such as a heater register. The PTC heater element is designed to be used in an automobile, such as an electric vehicle (xEV - x Electrical Vehicle).

[0016] The PTC heater element has at least one PTC element. Preferably, the PTC heater element has a plurality of PTC elements, such as 5, 10 or 20 PTC elements. The cavity between two successively following PTC elements can be filled with a heat-resistant filler. The filler functions as a mechanical protection or barrier against the ingress of moisture and as an additional heat conductor (instead of air).

[0017] The PTC element serves to generate heat. The PTC element has at least one electrode, in particular two electrodes, for electrical contact. The electrodes are formed on the surface of the PTC element.

[0018] The PTC heater element further has at least one additional contact. The additional contact serves for the electrical connection of the electrodes of the PTC element. The additional contact can comprise, for example, copper, aluminum and / or tungsten.

[0019] The PTC heater element also has at least one carrier layer. The carrier layer at least partially, preferably completely, surrounds the PTC element. The carrier layer is electrically insulating. The carrier layer has high thermal conductivity. The carrier layer serves to mechanically stabilize and electrically insulate the PTC heater element.

[0020] The PTC heater element is very compact. The PTC heater element has a large surface area and is thinly configured. The PTC heater element has an extremely small volume. The thickness of the PTC element is preferably ≤ 500 μm, preferably < 250 μm, for example 10 μm to 150 μm, and even < 2 μm. The height of the PTC heater element is between 500 μm and 2500 μm. The lateral dimension (L) of the PTC heater element (2) is between 10 mm and 250 mm in both directions (length and width).

[0021] Preferably, the PTC heater element is designed to be parallel to the surface. In particular, the carrier layer is preferably parallel to the surface. The PTC element is also preferably designed to be parallel to the surface.

[0022] The better the surface of the substrate / carrier layer is defined, the thinner it can be and the more efficiently heat transfer (to an aluminum heat sink etc.) can be carried out. Specifically, for the PTC element (~27×13 mm): < 100 μm, ideal: < 30 μm; for the (AlN or AlOx) carrier layer: (165×35 mm): 500 μm, ideal: < 100 μm.

[0023] For the performance of the PTC heater element, the flatness and parallelism of the PTC element and the carrier layer are important. If the surface of at least one PTC element / carrier layer is not correspondingly well-defined, the gap needs to be filled with a leveling compound or potting compound (Ausgleichs- oder Vergussmasse), increasing the thermal resistance. The more precisely the component is finished, the thinner the gap becomes.

[0024] Preferably, at least one PTC element is designed to be very thin, especially having a thickness of ≤ 250 μm and a flatness of < 100 μm. Particularly preferably, the flatness of the PTC element is < 30 μm. Preferably, the flatness of the carrier layer is < 500 μm, particularly preferably < 100 μm. With the configuration of the PTC heater element described above, a very compact design becomes possible, and thus a high degree of integration into the electric heater device becomes possible. As a result, compared with the heater devices of the prior art, a faster and more efficient heater effect (such as in a vehicle interior) is guaranteed. The weight reduction due to the reduction of the material usage enables an increase in the driving range of the xEV, and the low material consumption contributes to the conservation of resources and the reduction of the ecological footprint.

[0025] By an appropriate combination of materials and / or connection technologies, together with the optimization of the geometric shape at the heater element level, the volume and heat extraction of the PTC heater element are optimized so that the power density, heat response, and robustness and reliability are significantly improved compared to the state of the art.

[0026] According to one embodiment, the electrodes are arranged flat on the surface of at least one PTC element. The electrodes are formed directly on the surface of the PTC element. The electrodes can be sputtered, plated, printed on the surface of the PTC element, or coated (gerakelt) by a doctor blade or squeegee.

[0027] The electrodes are designed with as large an area as possible to achieve favorable heat extraction. The electrodes can be formed, for example, in a strip shape, rectangular shape, comb shape, or interdigital structure (Interdigitalstruktur). The electrodes need to be at a sufficient distance from each other to ensure the creep distance (Kriechstrecken freizuhalten) and avoid electrical flashover (elektrischen Ueberschlag). Thereby, a particularly reliable PTC heater element is obtained.

[0028] For example, at least one electrode is disposed on the upper or lower surface of the PTC element. Also, two electrodes can be formed on the upper or lower surface. Further, one electrode can be formed on each of the upper and lower surfaces.

[0029] Alternatively, the electrodes can be formed on the side surfaces of the PTC element, particularly on the opposing side surfaces. This separates the heat path and the electrical path from each other, enabling new designs and assemblies that are advantageous for certain manufacturers. Furthermore, the material non-uniformity of the PTC element due to manufacturing can be more appropriately controlled or avoided.

[0030] According to one embodiment, the further contacts are formed to be self-supporting. In other words, the carrier layer only stabilizes the other components of the PTC heater element. However, the carrier layer is not necessarily required to stabilize the further contacts.

[0031] Alternatively, the further contacts can also be applied onto the carrier layer for mechanical stabilization. For example, they can be coated onto the carrier layer by sputtering, printing, or using a doctor blade or squeegee.

[0032] According to one embodiment, the further contacts are integrated into the carrier layer. In other words, the further contacts are formed in the inner region of the carrier layer. In this case, the further contacts are disposed at a distance of ≤ 50 μm below the surface of the carrier layer.

[0033] According to an embodiment, the shape of the further contacts is adapted to the geometric shape of the electrodes of the PTC element. For example, the further contacts are designed to be as large in area and as thin as possible. For example, the thickness of the further contacts is < 10 μm. This increases the heat extraction of the PTC heater element and improves the efficiency.

[0034] According to one embodiment, further contacts are conductively connected to at least one electrode by means of clamping, sintering, adhesion, or high-temperature soldering. By using standard connection techniques, the manufacturing costs can be reduced, and as a result, a particularly cost-effective PTC heater element can be provided.

[0035] According to one embodiment, the carrier layer has a thickness between 150 μm and 1000 μm. Thereby, the carrier layer is designed to be very compact and thin in order to optimize the power density of the PTC heater element, but has a sufficient thickness to ensure the robustness and stability of the PTC heater element.

[0036] According to one embodiment, the carrier layer comprises a ceramic material having high thermal conductivity and good insulating properties. For example, the carrier layer has AlN, Si3N4, Al2O3, or SiC. These materials are ideal for optimizing heat extraction and increasing the power density and thermal responsiveness of the PTC heater.

[0037] Alternatively, the carrier layer can comprise a heat-resistant plastic. For example, the carrier layer consists of polyimide or epoxy resin. Due to the low thermal conductivity of the plastic (less than 10 W / mK), the thickness of the carrier layer has to be sufficiently thin in order to keep the thermal resistance low and achieve the high power density of the PTC heater element.

[0038] Alternatively, the carrier layer can also comprise a hybrid solution based on ceramic materials and plastics. For example, the carrier layer can have a plastic layer and a ceramic layer. In order to achieve optimal heat extraction, the plastic layer has to be considerably thinner than the ceramic layer.

[0039] According to one embodiment, the PTC heater element further has at least one metal layer on the surface of the carrier layer. The metal layer is used for further contact of the PTC heater element, for example, connection to a radiator. The metal layer can include, for example, Cu, Al, or W. The metal layer is formed very thin. Preferably, the metal layer has a thickness between 1 μm and 100 μm. Due to the thin thickness of the metal layer, it has no adverse effect on the thermal coupling of the PTC heater element.

[0040] According to one embodiment, at least one PTC element includes a ceramic material, a metal ceramic material, or an organic ceramic material. For example, the PTC element includes PZT (lead zirconate titanate). By using standard materials, a particularly cost-effective PTC heater element can be realized.

[0041] Alternatively, the PTC element can be based on bismuth. This has the advantage that the PTC element is lead-free. Alternatively, the PTC element can use a material that does not contain bismuth and lead.

[0042] According to one embodiment, the material of at least one PTC element has a low specific resistance. For example, the specific resistance is <5000 Ωcm, for example 1000 Ωcm. As a result, the PTC effect can be significantly reduced below the operating point, and thus the energy consumption / switch-on current in each switching-on process can be significantly reduced compared to conventional HV PTCs. This not only leads to a reduction in the load on other electronic components (reduction of the switch-on current), but also leads to a further improvement in the driving range of electric vehicles.

[0043] According to one embodiment, the PTC element is a low-temperature PTC element. This has the special advantage that the corresponding PTC element can be completely manufactured from a material that does not contain bismuth and lead.

[0044] According to one embodiment, the PTC heater element has a plurality of PTC elements. The PTC elements are arranged adjacent to each other (benachbart zueinander) or successively in series (aufeinander nachfolgend) on a carrier layer. In particular, the PTC elements are arranged successively in series in a direction along the main longitudinal axis X of the heater element. Further, the PTC elements are arranged successively in series in a direction perpendicular to the main longitudinal axis X (i.e., in a direction along the transverse axis Y).

[0045] By design, voids occur between the successively arranged PTC elements. The voids between two successively arranged PTC elements can be filled with electrodes for the electrical contact of the respective PTC elements. In particular, the voids along the main longitudinal axis X can be filled with an electrode material.

[0046] That is, contact by the electrodes is made from the opposing side surfaces of each PTC element. In other words, the contact of the PTC element is made from one end face (Stirnseite) of the PTC element. In this case, there are no electrodes on the upper and lower surfaces of the PTC element. This separates the heat path and the electrical path, enabling new designs and assemblies that are advantageous for certain manufacturers. Further, material inhomogeneities of the PTC elements due to manufacturing can be more appropriately controlled or avoided (besser beherrschbar bzw. umgehbar).

[0047] The remaining voids (voids perpendicular to the main longitudinal direction) between the PTC elements not filled with the electrode material can be filled with the above-described filler material, for example, to improve the thermal contact between the PTC elements.

[0048] According to one embodiment, the PTC heater element has a plurality of additional contacts. The additional contacts are formed directly on the carrier layer. In other words, no additional components of the PTC heater element are arranged between the additional contacts and the carrier layer.

[0049] Each additional contact is, for example, in the form of a strip. Preferably, the additional contact is formed as a metallization strip of the carrier layer. Preferably, the additional contact extends completely along the main longitudinal direction of the PTC heater element.

[0050] Additional contacts can be formed alternately on the upper and lower parts of the PTC element (especially the electrodes). This ensures reliable contact of the electrodes of the PTC element.

[0051] According to one embodiment, the PTC heater element further comprises at least one connecting element for the electrical connection between at least one PTC element and at least one additional contact. Preferably, the PTC heater element has a plurality of connecting elements.

[0052] At least one connecting element is formed in the shape of a strip. Each connecting element preferably extends at least partially along the main longitudinal direction of the PTC heater element. Each connecting element is formed at least between each additional contact and each electrode. Each connecting element is in direct contact with the electrode of at least one PTC element. The connecting element is also in direct contact with at least one, preferably exactly one additional contact. Preferably, at least one connecting element has a conductive adhesive.

[0053] Using the connecting element, a conductive and mechanically strong connection between the electrode and the additional contact can be ensured in a simple way. According to a further aspect, an electric heater device, for example a heater resistor, is described. The electric heater device comprises a component having a heat dissipation surface, for example cooling fins. The electric heater device further comprises at least one PTC heater element, preferably the PTC heater element described above. All the characteristics disclosed with respect to the PTC heater element are thus correspondingly disclosed with respect to each other aspect, and vice versa.

[0054] The optimized design of the PTC heater element enables advanced integration into the heater device. This results in a rapid and efficient heating effect (e.g., inside a vehicle).

[0055] According to a further aspect, the use of the above-described PTC heater element in a motor vehicle, such as an electric vehicle, is described. Since the PTC heater element has a very compact design, it is suitable for any installation situation. Furthermore, the PTC heater element can ensure optimal heat extraction, and thus high power density and reliability.

[0056] The drawings described below are not to be understood as being true to scale. Rather, individual dimensions may be enlarged, reduced, or distorted for better representation.

[0057] Elements that are similar to each other or perform the same function are given the same reference numeral.

Brief Description of the Drawings

[0058]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9a

Figure 9b

Figure 9c

Figure 9d

Figure 10

Figure 11a

Figure 11b

DETAILED DESCRIPTION OF THE INVENTION

[0059] Figure 1 is a cross - sectional view of a prior - art PTC heater element 100. The PTC heater element 100 has a plurality (four in this embodiment) of PTC elements 101 for heat generation. The PTC elements 101 are arranged in series in the longitudinal direction of the PTC heater element 100 and are separated from each other by gaps.

[0060] Electrical contacts 102 (for example, made of copper) are arranged on the upper and lower surfaces of the PTC element 101 for electrical connection of the PTC element 101.

[0061] The PTC heater element 100 further includes an insulating layer 103, which is arranged on the electrical contact 102 and electrically insulates the PTC heater element 100 from the outside, in particular, from a heat distributor or radiator 104 formed on the outer surface of the electrical PTC heater element 100.

[0062] Figure 2 shows a cross-sectional view of a further PTC heater element 110 according to the prior art. Again, the PTC element 111 is disposed between electrical contacts 112. An insulating layer 113 made of plastic (e.g., polyimide) is formed on the electrical contacts 112, electrically insulating the heater element 110.

[0063] Figure 3 shows a cross-sectional view of a further PTC heater element 120 according to the prior art. The PTC element 121 is connected by electrical contacts 122 and is insulated from the outside by a plastic molding 123 (e.g., epoxy resin). The PTC element 121 is completely surrounded by the molding 123.

[0064] Figure 4 shows a cross-sectional view of a further PTC heater element 130 according to the prior art. Here, the PTC element 131 is in direct contact with a radiator 132 to achieve optimal heat extraction. There is no electrical insulation.

[0065] Figure 6 shows a cross-sectional view of a PTC heater element 1 according to the first embodiment. The PTC heater element 1 is designed to be used in an automobile, such as an electric vehicle. The PTC heater element 1 is designed to be incorporated into an electrical device (e.g., an electric heater device) having a radiator or heat sink (not explicitly shown).

[0066] The PTC heater element 1 has a plurality of PTC elements 2 (see also FIGS. 9a - 9d). The PTC heater element 1 further has electrodes / electrical contacts 3, additional contacts / conductor paths 4, and a carrier layer / substrate 5.

[0067] The PTC element 2 functions as a heat source. In particular, Joule heat is generated by energizing the PTC element 2. In this embodiment, the heater element 1 has five PTC elements 2. Of course, more than five PTC elements 2, for example eight or ten PTC elements 2, may be provided, or less than five PTC elements 2, for example two PTC elements 2 or one PTC element 2, may be provided. The number of PTC elements 2 depends in particular on the requirements for the PTC heater element 1, its material composition, and the installation situation, for example inside an automobile.

[0068] The PTC elements 2 are arranged successively or in sequence (nacheinander bzw. aufeinanderfolgend) along the main longitudinal axis X of the PTC heater element 1. They include ceramic materials, metal-ceramic materials or organic-ceramic materials. For example, the PTC elements include PZT ceramics. Alternative compositions based on bismuth are also conceivable. This has the advantage that the PTC elements 2 can be made lead-free. It is also conceivable to make the PTC elements 2 completely free of lead and bismuth.

[0069] Due to the design, cavities perpendicular to the main longitudinal axis X may occur between the PTC elements 2. In this embodiment, these cavities are filled with a heat-resistant and thermally conductive filler 7, such as silicone or epoxy. The optional filler 7 functions as mechanical protection or a barrier against moisture ingress and also (instead of air) as an additional heat conductor.

[0070] Each PTC element 2 is very compact. In particular, the thickness d or extent (Ausdehnung) perpendicular to the main longitudinal axis X of each PTC element 2 (see also Fig. 9a) is between 50 μm and 250 μm. Preferably, the thickness d of each PTC element 2 is 200 μm or less.

[0071] To achieve the corresponding thickness d, each PTC element 2 can be manufactured by standard processes (pressing process or multilayer structure). However, if alternative manufacturing methods are used, even thinner PTC elements 2 (10 μm to 150 μm, or less than 2 μm) are possible. The thinner PTC layer can be obtained by applying it to the carrier layer 5 by screen printing, thereby enabling the thickness d of each PTC element 2 to be between 10 μm and 150 μm. These layer thicknesses can be further reduced by coating processes such as SolGel, inkjet printing or plasma jet processes, achieving a thickness d < 2 μm.

[0072] The lateral spread I (spread along the main longitudinal axis X and lateral spread) of each PTC element 2 is preferably between 5 mm and 100 mm (Figs. 9a and 9b).

[0073] For the electrical connection of each PTC element 2, as can be seen from Figs. 9a to 9d, the PTC element 2 has an electrical contact or electrode 3. The electrode 3 is formed flat on the surfaces 2a, 2b, 2c of each PTC element 2. The electrode 3 is formed over as large an area as possible to achieve suitable heat extraction. Also, the electrodes 3 of opposite polarities need to be sufficiently spaced from each other to prevent arcing (Ueberschlaege).

[0074] One electrode can be formed on each of the lower surface 2b and the upper surface 2a of the PTC element 2 (Fig. 9b). However, it is also possible to form two electrodes 3 on the upper surface 2a and no electrode 3 on the lower surface of the PTC element 2 (Figs. 9a and 9d), or vice versa.

[0075] As can be seen in Fig. 9c, it is also possible to contact via the electrode 3, for example, from the opposing side surfaces 2c of each PTC element 2. In this case, there is no electrode 3 on the upper surface 2a and the lower surface 2b. The heat path and the electrical path are separated, enabling new designs and assemblies that are advantageous for specific manufacturers. Furthermore, it becomes possible to more appropriately control or avoid material non-uniformity of the PTC element 2 caused by manufacturing. Figs. 10 and 11b show embodiments of the PTC heater element 1 provided with the correspondingly contacting PTC elements 2.

[0076] The electrode 3 is designed to have as large a surface area as possible while maintaining a creepage distance (usually 4 mm in a high-voltage heater). The electrode 3 at least partially covers the upper surface 2a or the lower surface 2b of the PTC element. When the electrode 3 is arranged on the side surface 2c, the side surface 2c can also be completely covered by the electrode 3. For example, the electrode is in a strip shape or a rectangular shape (Figs. 9a and 9c). Also, a comb shape or an interdigital structure is possible (Figs. 9b and 9d). In an interlocking electrode structure, special attention should be paid to ensuring that the distance between the electrodes 3 is sufficient to avoid an electrical flashover.

[0077] The electrode 3 has a conductive material (for example, a metal paste). The conductive material is coated on the surfaces 2a, 2b, 2c of each PTC element 2 by sputtering, printing, or using a doctor blade or squeegee. The electrode 3 is preferably realized by a sputter layer or a metal fired paste.

[0078] By using the described electrode configuration (see Figs. 9a - 9d), different specific resistances are required for the PTC material compared to the prior art. This additional degree of freedom means that when the specific resistance is low, the PTC effect significantly decreases below the operating point, and thus, for conventional HV (high-voltage) PTCs, the energy consumption or inrush current in each switch-on process is significantly reduced. As a result, the load becomes lower (the inrush current becomes lower).

[0079] Figure 5 shows the standardized characteristic curves (same measurement voltage) showing the resistance-temperature behavior of HVPTC ceramics at two different specific resistances. Due to the low specific resistance, the resistance drop is significantly reduced compared to the conventional high specific resistance.

[0080] To make electrical contact with the electrode 3, the PTC heater element 1 further has the conductor path or further contacts as described above. In this embodiment, the conductor path or further contact 4 extends through the PTC heater element 1 along the upper surface 2a and the lower surface 2b of the PTC element 2. In other words, the further contact 4 according to FIG. 6 is formed between the PTC element 2 (or the electrode 3) and the carrier layer 5. In particular, the further contact 4 is in direct contact with the electrode 3 of the PTC element 2.

[0081] The further contact 4 extends along the main longitudinal axis X. The further contact 4 exits from the side surface 1a of the PTC heater element 1 for the electrical connection of the PTC heater element 1.

[0082] The conductive connection between the electrode 3 and the further contact 4 can be realized using various technical solutions. Clamp contacts are possible in the same way as connections by sintering techniques (μAg, μCu, TLPS (Transient Liquid Phase Sintering)), or high-temperature soldering.

[0083] The further contact 4 is self-supporting. This means that no further elements (such as a carrier layer or substrate 5) are required for the mechanical stabilization of each further contact 4. Alternatively, the further contact 4 can be applied to the carrier layer 5. In this case, the further contact 4 is coated on the carrier layer 5 by sputtering, plating, printing, or doctor blade or squeegee. As described above, as can be seen in FIG. 6, the further contact 4 of the two embodiments described above is in direct electrical and mechanical contact with the electrode 3.

[0084] The further contact 4 has, for example, copper, aluminum, tungsten. However, other conductive metals, alloys, or other conductive materials are also conceivable for the further contact 4. The geometric shape of each further contact 4 is adapted to the geometric shape of the electrode 3 of the PTC element 2 so that no electric field surge or flashover occurs during the operation of the PTC element 2.

[0085] Preferably, the further contact 4 is designed with a large surface area. Each further contact 4 is designed to be as thin as possible in order to save space (Bauraum). Preferably, the thickness of the further contact 4 is <10 μm. This is particularly possible when the further contact 4 is applied to the carrier layer 5 by sputtering, printing, or coating (Rakeln) with a doctor blade or squeegee, as already described above.

[0086] The PTC heater element 1 also has the already introduced carrier layer 5. The carrier layer 5 serves to electrically insulate the PTC heater element 1 from the outside and to mechanically stabilize the PTC heater element 1. The PTC element 2 is arranged over the entire inner region of the carrier layer 5. The further contact 4 is also at least partially embedded in the carrier layer 5.

[0087] The carrier layer 5 has a very small thickness (spread perpendicular to the main longitudinal axis X). For example, the thickness of the carrier layer 5 is between 150 μm and 1000 μm. Thereby, not only the heat due to ohmic losses in the supply line but also the heat transfer of the heater element can be conducted to the outside as efficiently as possible.

[0088] The carrier layer 5 further includes a material having high thermal conductivity and good electrical insulation properties. In this embodiment, the carrier layer 5 includes a ceramic material, such as AlN, Si3N4, Al2O3 or SiC. By using the carrier layer 5 that conducts heat particularly well (for example, in the case of AlN: up to 200 W / mK), the cable cross-sectional area for electrical contact can be reduced. This is because heat is immediately dissipated through the carrier layer 5 due to ohmic losses.

[0089] In an alternative embodiment, the carrier layer 5 can also include a heat-resistant plastic (such as polyimide or epoxy resin). In this case, based on the low thermal conductivity of the plastic (<10 W / mK), the thickness of the carrier layer 5 must be designed to be thin enough so that the thermal resistance is sufficiently small.

[0090] In other words, the plastic carrier layer 5 must be much thinner than the ceramic carrier layer. In particular, the plastic layer must be thin enough to ensure heat transport, but thick enough to ensure electrical insulation and mechanical stability of the PTC heater element 1. For example, the plastic carrier layer 5 has a thickness of 50 μm. In order to make the area contributing to heat conduction in the carrier layer 5 as large as possible, the electrical supply lines (electrodes 3, further contacts 4) can also function as heat spreaders.

[0091] A hybrid solution of ceramic-based and plastic-based carrier layers is also possible (see the description of FIG. 8 below).

[0092] Also, in this embodiment, a metal layer 6 is further formed on the surface 5a of the carrier layer 5. The metal layer 6 completely covers the upper and lower surfaces of the carrier layer 5. The metal layer 6 facilitates mechanical and thermal contact with a (metal) radiator or heat sink (not explicitly shown). The metal layer 6 is very thin. For example, the thickness of the metal layer 6 is between 1 μm and 100 μm. The metal layer 6 includes Cu, Al or W.

[0093] Overall, the total height (Bauhoehe) H of the PTC heater element 1 is between 500 μm and 2500 μm due to the above-described structure. The lateral dimension L of the PTC heater element 1 is between 10 mm and 250 mm in both directions (lateral dimension L: length, i.e., the extent along the main longitudinal axis X, and width, i.e., the extent transverse to the main longitudinal axis X).

[0094] Thus, the PTC heater element 1 is extremely compact, especially with a large surface area and being thin. By appropriately combining the materials and connection techniques described above and thus optimizing the geometric shape at the heater element level, the volume and heat extraction of the PTC heater element 1 are optimized such that the power density, thermal response behavior, and robustness and reliability are significantly improved compared to the prior art level.

[0095] Due to the design of the PTC heater element 1 being very efficient, thin, and powerful, the use of low-temperature PTC is also possible. These can be made of materials that are completely free of bismuth and lead.

[0096] FIG. 7 shows a cross-sectional view of the PTC heater element 1 according to a further embodiment. In contrast to the example shown in FIG. 6, a further contact 4 is not formed between the carrier layer 5 and the PTC element 2. Rather, the further contact 4 is integrated into the carrier layer 5. Only on the side surface 1a of the PTC heater element 1 does the further contact 4 emerge from the carrier layer 5 in order to ensure the electrical connection of the PTC heater element 1.

[0097] In this embodiment, the carrier layer 5 preferably contains AlN. Each further contact 4 contains a tungsten (W) layer. In other words, the further contact 4 embedded in the carrier layer 5 is preferably realized by a W contact in the AlN carrier layer 5. The W layer preferably has a thickness of 5 μm to 20 μm. The W layer is preferably mounted on a large area of the carrier layer 5.

[0098] As already described in connection with FIG. 6, the carrier layer 5 has a typical thickness of 150 μm to 1000 μm. The W layer can be formed symmetrically within the central region of the carrier layer 5 or offset towards the central region. In the embodiment according to FIG. 7, each additional contact 4 (W layer) is formed offset from the central region of the carrier layer 5 towards the PTC element 2. In any case, the W layer is disposed at least 50 μm below the surface of the carrier layer 5.

[0099] In this embodiment, the PTC heater element 1 further comprises a through-hole / via 8. The via 8 preferably contains tungsten. Preferably, the via 8 consists of tungsten. However, the via 8 can also contain other conductive materials or consist of other conductive materials.

[0100] The via 8 completely penetrates the carrier layer 5 in a direction perpendicular to the main longitudinal axis X of the PTC heater element 1. The via 8 establishes a conductive connection between the electrode 3 of the PTC element 2 and the W layer (additional contact 4).

[0101] Regarding the characteristics of the PTC heater element 1 or other components / features, refer to the description related to FIG. 6.

[0102] FIG. 8 shows a cross-sectional view of a PTC heater element 1 according to a further embodiment. In this embodiment, the carrier layer 5 has a hybrid solution based on ceramic material and plastic material. In particular, the PTC heater element 1 has a heat-resistant plastic layer 9 (such as polyimide or epoxy resin) on one side (in this case the upper side). On the opposite side (here the lower side), as already explained in connection with FIG. 6, the PTC heater element 1 has a carrier layer 5 made of ceramic material. Of course, it is also possible to form the plastic 9 on the lower side and the ceramic carrier material on the upper side.

[0103] The ceramic carrier layer 5 serves to mechanically stabilize and insulate the PTC heater element 1 (in this case, insulation on the lower surface). The plastic layer 9 serves to insulate the PTC heater element 1 (in this case, insulation on the upper surface). Both layers must have a thickness sufficient to ensure electrical insulation, but must also be thin enough to ensure heat transport. In particular, since the thermal conductivity of the plastic is low (<10 W / mK), the thickness of the plastic layer 9 must be thin enough to keep the thermal resistance sufficiently low, as already explained in connection with the embodiment according to FIG. 6.

[0104] In particular, the plastic layer 9 is thinner than the ceramic layer 5. For example, in this embodiment, the thickness of the ceramic carrier layer 5 is 10 to 100 times the thickness of the plastic layer 9. The thickness of the plastic layer 9 is between 2 μm and 50 μm. For example, the thickness of the plastic layer is 30 μm. The ceramic carrier layer 5 has a thickness between 0.5 mm and 1 mm in order to ensure the mechanical stability of the PTC heater element 1.

[0105] For further properties or further components / features of the PTC heater element 1, reference is made to the description related to FIG. 6.

[0106] FIG. 11a shows the PTC heater element 1 according to the above. In particular, FIG. 11a shows a plurality of PTC elements 2 arranged successively along the main longitudinal axis X of the heater element 1. Each PTC element 2 is in contact from the upper surface 2a or the lower surface 2b via an electrode 3 (see in particular FIGS. 6a, 9a, 9b and 9d).

[0107] The connection of the electrode 3 is made from the upper surface 2a or the lower surface 2b of the PTC element 2 via a further strip-shaped contact 4. A connection element 10, for example a conductive adhesive, is formed between the electrode 3 and the further contact 4 to establish an electrical and mechanical connection between the further contact 4 and the electrode 3.

[0108] Furthermore, a filler 7 can also be introduced into the cavity between two consecutive PTC elements 2 (not explicitly shown in the figures, see FIG. 6).

[0109] FIGS. 10 and 11b show a PTC heater element 1 according to a further embodiment. The PTC heater element 1 is designed for use in a motor vehicle, for example an electric vehicle, as already described above. The PTC heater element 1 is designed to be incorporated into an electrical device (for example an electric heater device) having a radiator or heat sink (not explicitly shown).

[0110] The PTC heater element 1 has electrodes / electrical contacts 3, further contacts 4, and a carrier layer / substrate 5. The carrier layer 5 preferably comprises ceramic. The PTC heater element 1 also comprises a connection element 10, as will be explained in more detail below.

[0111] The PTC heater element 1 has a plurality of PTC elements 2. The PTC elements 2 have a smaller spread in a direction perpendicular to the main longitudinal axis X of the PTC heater element 1 compared to the above-described design (see also FIG. 11a in particular). In other words, the PTC elements 2 according to FIGS. 10 and 11a have a shorter length, for example, than the PTC elements 2 according to FIG. 11a.

[0112] The PTC elements 2 are arranged adjacent to each other or consecutively (benachbart zueinander bzw. aufeinander nachfolgend) on the carrier layer 5. In particular, the plurality of PTC elements 2 are arranged consecutively along the main longitudinal axis X of the heater element 1. Furthermore, the PTC elements 2 are arranged consecutively in a direction perpendicular to the main longitudinal axis X (i.e., along the lateral axis Y).

[0113] As already explained in connection with FIG. 6, a cavity is created between the PTC elements 2 in the design (see also FIG. 11a). In this embodiment, the cavity extends parallel and laterally to the main longitudinal axis X (see FIG. 11b).

[0114] The cavity in the lateral direction with respect to the main longitudinal axis X can be filled with the heat-resistant filler 7 as in the above-described embodiment (not explicitly shown, see particularly FIG. 6). Thereby, the thermal contact between the PTC elements 2 can be improved.

[0115] In the embodiment according to FIGS. 10 and 11b, the cavity parallel to the main longitudinal axis X is further filled with an electrode material. In other words, the electrodes 3 for making electrical contact with the two PTC elements 2 are formed in respective cavities extending along the main longitudinal axis X between two successive PTC elements 2 facing each other in a direction perpendicular to the main longitudinal axis X (i.e., along the transverse axis Y).

[0116] Each electrode 3 represents a metallized part. Each electrode 3 completely covers the side surface 2c (particularly the short side surface) of each PTC element 2 (see also the embodiment according to FIG. 9c). That is, in the embodiment according to FIGS. 10 and 11b, the contact of the PTC element 2 is made from one end face of the PTC element 2. In contrast, in the above-described embodiments (see, for example, FIGS. 6 and 11a), the PTC element 2 is contacted from the upper surface 2a and / or the lower surface 2b of the PTC element 2.

[0117] Each electrode 3 or metallized part completely fills the cavity between the PTC elements 2. The electrodes 3 of opposite polarities are arranged alternately. That is, the first cavity between two successive PTC elements 2 along the direction of the transverse axis Y is filled with the electrode 3 of the first polarity. The second cavity continuous along the direction of the transverse axis Y is filled with the electrode 3 of the opposite polarity. Two successive PTC elements 2 always share the electrode 3 or metallized part and are thus contacted by a common metallized part.

[0118] To make electrical contact with the electrode 3, the PTC heater element 1 also has the above-described further contacts 4, particularly a plurality of further contacts 4. The further contacts 4 are formed between the PTC element 2 (particularly the electrode 3) and the carrier layer 5.

[0119] From this, a further contact 4 is formed, in particular, at the interface between two PTC elements 2 following one another in the direction of the transverse axis Y. In other words, the further contact 4 covers at least a cavity filled with electrode material that extends along the main longitudinal axis X or parallel to the main longitudinal axis X.

[0120] The further contacts 4 are arranged alternately on the upper surface 2a and the lower surface 2b of the PTC element 2 (see also Fig. 11a). The further contacts 4 formed on the upper surface 2a establish an electrical connection to the end-face-side electrodes 3 of the first polarity. The further contacts 4 formed on the lower surface 2b establish an electrical connection to the end-face-side electrodes 3 of the opposite polarity.

[0121] The further contacts 4 are designed in strip shape. The further contacts 4 extend completely along the main longitudinal axis X. The individual further contacts 4 are parallel to one another along the main longitudinal axis X.

[0122] The further contacts 4 can emerge from the side surface 1a of the PTC heater element 1 (see Fig. 6) for the electrical contact of the heater element 1. The further contacts 4 represent the metallization of the carrier layer 5. In particular, the further contacts 4 in this exemplary embodiment correspond to metallization strips on the surface 5a of the carrier layer 5. The further contacts 4 are in direct contact with the carrier layer 5.

[0123] The conductive connection between the electrode 3 and the further contact 4 is realized via the connecting element 10. Each connecting element 10 includes, for example, a conductive adhesive.

[0124] The connecting element 10 is formed between the PTC element 2 (in particular the electrode 3) and the further contact 4. The connecting element 10 is in direct contact, in particular, with the electrode 3 (here the end-face side) of the PTC element 2 and the further contact 4. The connecting element 10 is designed in strip shape. Each connecting element 10 extends at least partially along the main longitudinal axis X.

[0125] In the embodiment according to FIGS. 10 and 11b, one connecting element 10 is formed at the interface between two PTC elements 2 that are successively continuous in the direction of the transverse axis Y. In other words, each connecting element 10 covers at least one cavity filled with electrode material that extends parallel to the main longitudinal axis X. Of course, the connecting element 10 can also be formed longer so as to extend over a plurality of cavities and thus more than two PTC elements 2 (not explicitly shown).

[0126] For all further features regarding the PTC element 2, the carrier layer 5, the further contacts 4 and the electrodes 3, especially with regard to the composition and dimensions of the components, reference is made to the above description. The description of the objects shown here is not limited to individual specific embodiments. Rather, the features of the individual embodiments can be combined with one another in any way as long as they are technically meaningful.

Explanation of reference numerals

[0127] 1 PTC heater element 1a Side surface of the PTC heater element 2 PTC element 2a Upper surface of the PTC element 2b Lower surface of the PTC element 2c Side surface of the PTC element 3 Electrode 4 Further contact 5 Carrier layer 5a Surface of the carrier layer 6 Metal layer 7 Filler 8 Through hole / via 9 Plastic 10 Connecting element l Length of the PTC element d Thickness of the PTC element H Height of the PTC heater element L Lateral dimension of the PTC heater element X Main longitudinal axis of the PTC heater element Y Transverse axis of the PTC heater element 100 PTC heater element 101 PTC element 102 Electrical contact 103 Insulating layer 104 Radiator 110 PTC heater element 111 PTC element 112 Electrical contact 113 Insulating layer 120 PTC heater element 121 PTC element 122 Electrical contact 123 Mold 130 PTC heater element 131 PTC element 132 Radiator

[0128] [Appendix 1] A PTC heater element (1) for an electric heater device, - at least one PTC element (2), on the surface (2a, 2b, 2c)) of which at least one electrode (3) is formed for electrical contact of the PTC element (2), at least one PTC element (2); - at least one further contact (4) for electrical connection of the electrode (3) of the PTC element (2); - at least one carrier layer (5), which is formed to be electrically insulating, at least one carrier layer (5), comprising; The thickness (d) of the PTC element (2) is ≦ 500 μm, The height (H) of the PTC heater element (1) is between 500 μm and 2500 μm, PTC heater element. [Appendix 2] The lateral dimension (L) of the PTC heater element (2) is between 10 mm and 250 mm in both directions, The PTC heater element according to Appendix 1. [Appendix 3] The at least one electrode (3) is formed flat on the surface of the at least one PTC element (2). The PTC heater element according to appended claim 1 or 2. [Appended claim 4] At least one electrode (3) is formed on each of the upper surface (2a) and / or the lower surface (2b) of the PTC element (2), and / or an electrode (3) is formed on the side surface (2c) of the PTC element (2). The PTC heater element according to any one of appended claims 1 to 3. [Appended claim 5] The at least one electrode (3) is formed in a strip shape, a rectangular shape, a comb shape, or an interdigital structure, and / or The electrode (3) is coated on the surface (2a, 2b, 2c) of the PTC element (2) by sputtering, plating, printing, or doctor blading or squeegee. The PTC heater element according to any one of appended claims 1 to 4. [Appended claim 6] The further contact (4) is formed to be self-supporting, or the further contact (4) is coated on the carrier layer (5) by sputtering, printing, or doctor blading or squeegee. The PTC heater element according to any one of appended claims 1 to 5. [Appended claim 7] The further contact (4) is integrated into the carrier layer (5), and the further contact (4) is disposed at a position of ≤ 50 μm below the surface (5a) of the carrier layer (5). The PTC heater element according to any one of appended claims 1 to 5. [Appended claim 8] The geometric shape of the further contact (4) is adapted to the geometric shape of the electrode (3) of the PTC element (2). The PTC heater element according to any one of appended claims 1 to 7. [Appended claim 9] The thickness of the further contact (4) is < 10 μm. The PTC heater element according to any one of Appendices 1 to 8. [Appendix 10] The at least one further contact (4) is conductively connected to the at least one electrode (3) by means of clamping, adhesion, sintering, or high-temperature soldering. The PTC heater element according to any one of Appendices 1 to 9. [Appendix 11] The carrier layer (5) comprises a ceramic material having high thermal conductivity and / or a heat-resistant plastic. The PTC heater element according to any one of Appendices 1 to 10. [Appendix 12] The carrier layer (5) comprises AlN, Si3N4, Al2O3, or SiC, and / or the carrier layer (5) comprises a polyimide or an epoxy resin. The PTC heater element according to any one of Appendices 1 to 11. [Appendix 13] The carrier layer (5) has a thickness between 150 μm and 1000 μm. The PTC heater element according to any one of Appendices 1 to 12. [Appendix 14] For a further contact of the PTC heater element (1), at least one metal layer (6) is further provided on the surface (5a) of the carrier layer (5). The PTC heater element according to any one of Appendices 1 to 13. [Appendix 15] The metal layer (6) has a thickness between 1 μm and 100 μm. The PTC heater element according to Appendix 14. [Appendix 16] The at least one PTC element (2) comprises a ceramic material, a metal ceramic material, or an organic ceramic material. The PTC heater element according to any one of Appendices 1 to 15. [Appendix 17] The material of the at least one PTC element (2) has a low specific resistance. The PTC heater element according to any one of Appendices 1 to 16. [Appendix 18] The material of the at least one PTC element (2) includes a material that does not contain bismuth and lead. The PTC heater element according to any one of Appendices 1 to 17. [Appendix 19] The at least one PTC element (2) is a low-temperature PTC element. The PTC heater element according to any one of Appendices 1 to 18. [Appendix 20] The thickness (d) of the PTC element (2) is ≦ 250 μm. The PTC heater element according to any one of Appendices 1 to 19. [Appendix 21] At least one PTC element (2) and / or at least one carrier layer (5) are formed parallel to the surface. The PTC heater element according to any one of Appendices 1 to 20. [Appendix 22] The at least one PTC element (2) has a surface parallelism of < 100 μm, and / or the at least one carrier layer (5) has a surface parallelism of < 500 μm. The PTC heater element according to Appendix 21. [Appendix 23] The at least one PTC element (2) is at least partially embedded in the carrier layer (5). The PTC heater element according to any one of Appendices 1 to 22. [Appendix 24] Comprising a plurality of PTC elements (2). The hollow space between two consecutively arranged PTC elements (2) is filled with a heat-resistant filler. The PTC heater element according to any one of Appendices 1 to 23. [Appendix 25] Comprising a plurality of PTC elements (2). The hollow space between two consecutively arranged PTC elements (2) is filled with an electrode (3) for the contact of each PTC element (2). The PTC heater element according to any one of Appendices 1 to 24. [Appendix 26] The contact of each of the PTC elements is made from the end face of the PTC element (2), The PTC heater element according to appended note 25. [Appended note 27] Comprising a plurality of further contacts (4), Each of the further contacts (4) is formed in a strip shape, The PTC heater element according to any one of appended notes 1 to 26. [Appended note 28] The further contacts (4) are alternately formed on the upper surface (2a) and the lower surface (2b) of the PTC element (2), The PTC heater element according to appended note 27. [Appended note 29] Further comprising at least one connecting element (10) for the electrical connection between the at least one PTC element (2) and the at least one further contact (4), The PTC heater element according to any one of appended notes 1 to 28. [Appended note 30] The at least one connecting element (10) is formed in a strip shape, The PTC heater element according to appended note 29. [Appended note 31] Comprising a plurality of connecting elements (10), Each of the connecting elements (10) is formed at least between each of the further contacts (4) of the PTC element (2) and each of the electrodes (3), The PTC heater element according to appended note 29 or 30. [Appended note 32] The at least one connecting element (10) contains a conductive adhesive, The PTC heater element according to any one of appended notes 29 to 31. [Appended note 33] - At least one PTC heater element (1) according to any one of appended notes 1 to 32 and - At least one element having a surface for discharging heat, An electric heater device comprising. [Appendix 34] A method of using a PTC heater element according to any one of Appendices 1 to 32 in an automobile.

Claims

【Claim 1】 A PTC heater element (1) for an electric heater device, comprising: - at least one PTC element (2) having at least one electrode (3) formed on the surface (2a, 2b, 2c)) of the PTC element (2) for electrical contact with the PTC element (2); - at least one further contact (4) for electrical connection of the electrode (3) of the PTC element (2); - at least one carrier layer (5) formed to be electrically insulating; wherein the thickness (d) of the PTC element (2) is ≦ 500 μm; and the height (H) of the PTC heater element (1) is between 500 μm and 2500 μm. PTC heater element.

Images