Method for manufacturing a PTC heating element

Abstract

A method for manufacturing a PTC heating element, wherein the PTC heating element (10) comprises at least one PTC component (20) and a support (14, 16) firmly connected to the at least one PTC component (20) on at least one side (50, 52), wherein at least one support (14, 16) to be connected to the at least one PTC component (20) is plate-like and constructed with electrically insulating material, wherein at least one contact field (36) is provided on at least one support (14, 16) constructed with the electrically insulating material in the method, and wherein the method comprises the following measures: a) Arranging solder material (46, 48) between at least one side (50, 52) of at least one PTC component (20) to be firmly connected to a support (14, 16) and a support to be connected to the at least one PTC component (20) on this side (50, 52), wherein the measure a) comprises, prior to arranging the solder material (46, 48), providing a coating (24, 26, 54, 56) of metal material on a side of at least one support (14, 16) to be positioned facing the at least one PTC component (20). b) Melting the solder material (46, 48) and thereby connecting the at least one PTC component (20) with at least one support (14, 16), characterized in that, - that measure b) includes melting the solder material (46, 48) by induction soldering, - that at least one contact field (36) is provided on a side (38, 40) of the carrier (14, 16) facing away from the at least one PTC component (20) by means of the coating (24, 26) provided on at least one carrier (14, 16) which is constructed with the electrically insulating material, - that a connection area (42) is formed for connecting an area of ​​the coating (24, 26) provided on the side of this carrier (14, 16) facing the at least one PTC component (20) with an area of ​​the coating (24, 26) provided on the side (38, 40) of this carrier (14, 16) facing away from the at least one PTC component (20), and - that the connection area (42) is provided by the coating (24) extending around an end face (58) of this carrier (14, 16) or by material of the coating (24) arranged in one or more openings (44) formed in the carrier (14, 16).

Description

[0001] The present invention relates to a method for manufacturing a PTC heating element.

[0002] In vehicle manufacturing, PTC heating elements are used to heat gaseous or liquid media, for example, to transfer heat to the air being introduced into a vehicle interior. The use of PTC heating elements is particularly relevant for purely electric vehicles where other heat sources, such as an internal combustion engine or a fuel-powered heater, are not available. These PTC heating elements are also used in other areas, such as heating trains or fuel cells.

[0003] A method for manufacturing a PTC heating element according to the preamble of claim 1 is known from EP 0 026 457 A2. In this method, a silver-containing metallization layer is applied to the sides of plate-like carriers made of insulating material, which are to be positioned facing a PTC component and connected to it by solder, before the solder is applied. A region of the solder extending beyond the PTC element forms a contact field on each of the carriers, at which an electrically conductive contact is generated with a contact tab penetrating a frame.

[0004] The object of the present invention is to provide a method for manufacturing a PTC heating element and a PTC heating element, with which efficient heating operation of a PTC heating element is achieved while making the manufacturing process simple and cost-effective.

[0005] This problem is solved by a method for manufacturing a PTC heating element according to claim 1, wherein the PTC heating element comprises at least one PTC component and a support firmly connected to the at least one PTC component on at least one side, wherein the method comprises the following measures: a) Arranging solder material between at least one side of at least one PTC component to be firmly connected to a carrier and a carrier to be connected to the at least one PTC component on that side, b) Melting the solder material by induction soldering and thus connecting the at least one PTC component to at least one support.

[0006] The inventive method for manufacturing a PTC heating element offers the possibility of distributing the energy required to melt the solder evenly over a larger area or volume in a connection process that can be carried out with relatively simple technical means. This ensures that the solder, used to create both a solid mechanical connection and an electrically conductive connection with the PTC component, melts uniformly. Since essentially no other materials are required besides this solder to create a planar mechanical and electrically conductive connection to a PTC component, the assembly is compact and mechanically and thermally stable. At the same time, the use of both the solder and the material creating the mechanical connection ensures good heat dissipation from the PTC component.

[0007] In measure a), the solder material can be applied to at least one side of the PTC component that is to be connected to a substrate. Alternatively or additionally, in measure a), the solder material can be applied to at least one substrate that is to be connected to the at least one PTC component.

[0008] To achieve a uniform distribution of the soldering material, it is proposed that in measure a) the soldering material be applied in a flowable state, preferably by screen printing. Other methods for applying flowable, for example, pasty material, such as applying this material to a surface to be coated and distributing the flowable material on this surface using a squeegee or similar tool, can also be used.

[0009] In an alternative approach, in measure a), the solder material can be positioned between the at least one PTC component and the at least one substrate to be joined by placing a solder material mold between it. This eliminates the need for applying and distributing flowable material. Simultaneously, the amount of solder material used in a specific area is precisely defined by the size of such a solder material mold.

[0010] To achieve particularly good adhesion and thus increased stability of the mechanical connection, the method according to the invention provides that measure a) before the soldering material is applied, includes applying a coating of metal material to at least one carrier to be connected to the at least one PTC component. Additionally, such a coating can be provided on at least one side of the at least one PTC component to be connected to a carrier.

[0011] One possible method involves applying a flowable, metal-containing coating material, preferably by screen printing, and curing the coating material on at least one side of the at least one PTC component and / or at least one support to be connected to the at least one PTC component. Other methods for applying the flowable coating material are also possible.

[0012] The coating material can contain, for example, aluminum and / or silver and can be heated and cured at a temperature in the range of 600°C to 900°C.

[0013] For a stable, flat connection, at least one support must be designed in a plate-like form.

[0014] Depending on the environment in which such a PTC heating element is to be used, at least one support to be connected to the at least one PTC component can be made of ceramic material, so that electrical insulation of the PTC heating element to the outside can also be achieved by such a support made of ceramic material.

[0015] Since at least one PTC component is connected to one or more carriers made of electrically insulating material, such as ceramic material, at least one contact field is provided on at least one carrier made of electrically insulating material, such as ceramic material, to enable an electrical connection to a voltage source.

[0016] To achieve a particularly simple design, at least one contact field is provided by the coating on a substrate made of an electrically insulating material, such as ceramic. This metal layer thus serves two purposes: firstly, to provide a good mechanical connection between the substrate and a PTC component, and secondly, to allow for the connection of an electrical conductor to a voltage source.

[0017] The present invention is described in detail below with reference to the accompanying figures. These show: Fig. 1. A PTC heating element in perspective view; Fig. 2 the PTC heating element of the Fig. 1 in exploded view; Fig. 3 A longitudinal section view of a PTC component to be connected to a carrier using solder material Fig. 4 in their presentations a) and b) alternatives for the design of a contact field; Fig. 5 another longitudinal section view of a PTC component to be connected to a carrier by soldering material; Fig. 6 Another longitudinal section view of a PTC component to be connected to a carrier using soldering material.

[0018] The Fig. Figure 1 shows a perspective view of a PTC heating element 10, which can be used in various heating systems, such as electrically powered vehicles, trains, fuel cells, or the like. The essentially plate-shaped PTC heating element 10, which is Fig. The assembly shown in exploded view 2 is constructed with two plate-like supports 14, 16. These two plate-like supports 14, 16 are made, for example, of ceramic material such as aluminum oxide, aluminum nitride, silicon nitride, silicon carbide, or the like. Between these two plate-like supports 14, 16, the heat-generating PTC component 20, which is surrounded by a frame 18 also made, for example, of ceramic material such as aluminum oxide, aluminum nitride, silicon nitride, silicon carbide, or the like, is arranged, for example, also in a plate-like shape. The frame 18 has an opening 22 adapted to the outer contour and outer dimensions of the PTC component 20 and is preferably shaped and dimensioned in its outer circumference region such that, when assembled with the two supports 14, 16 arranged on either side of it, it is essentially flush, i.e.,, does not protrude laterally outwards or is recessed.

[0019] To create a secure connection between the PTC component 20 and the two carriers 14, 16 that also allows for electrical contact, a coating 24, 26 made of a metal-containing material, such as aluminum or silver, is first applied to the carriers 14, 16. This can be done, for example, by applying the flowable, e.g., pasty, metal-containing coating material in a screen printing process or a similar coating process, using a squeegee or similar tool. The carriers 14, 16 are coated with this metal-containing coating material on their sides 28, 30 facing the PTC component 20. The coating is applied to the sides 28, 30 of the carriers 14, 16 facing the PTC component 20 in such a way that a Fig. 3 in conjunction with the carrier 14, the PTC component connection area V is covered with the coating material, while a respective edge area 32, 34 surrounding the PTC component connection area V remains largely free.

[0020] To form a in Fig. 3 in connection with carrier 14, the contact field 36 to be identified, the carriers 14, 16 in a Fig. 3. The contact field area K, also recognizable in connection with the carrier 14, is coated on its respective sides 38, 40 facing away from the PTC component 20 with the coating 24, 26 made of metal-containing material. In the Fig. In the embodiment shown in Figure 3, the areas of the respective coating 24, 26 formed on the two sides 28, 38 and 34, 40 of the carriers 14, 16 are connected to each other by a connecting area 42 in one or more openings 44 formed in the respective carrier 14, 16.

[0021] After the metal-containing coating material intended for forming the coatings 24, 26 has been applied to the substrates 14, 16, each of the substrates 14, 16 is heated or baked out so that these coatings 24, 26 are cured and form a strong bond with the substrates 14, 16. Depending on the metal-containing material intended for the coatings 24, 26, this can take place at a temperature of, for example, up to 800°C.

[0022] After the coatings 24, 26 have been applied and cured, solder material 46, 48 is applied to them, preferably limited to the PTC component connection area V. The solder material 46, 48 can also be applied as a flowable, pasty material in a screen printing process or another coating process. In an alternative embodiment, the solder material 46, 48 can each be formed as a solder material component between a respective carrier 14, 16 or 16.The coating 24, 26 provided in the PTC component connection area V and the PTC component 20 are positioned so that a layered structure of the two carriers 14, 16 with the PTC component 20 arranged between them and also the frame 18 positioned between the two carriers 14, 16 and, after application of the coatings 24, 26, firmly connected to one of the carriers 14, 16, for example in the edge area 32, 34 not coated with the respective coating 24, 26, is obtained, for example by material bonding, e.g. adhesive bonding. In order to achieve a layering leading to a full-surface and stable connection contact, the frame 18 is constructed with a thickness measured between the two carriers 14, 16 that is at least no greater than the material thickness of the PTC component 20, and preferably less than this material thickness.

[0023] Subsequently, an induction soldering process is carried out on this layered structure in an induction soldering device, so that the solder material 46, 48 melts over a surface and, after cooling, creates a firm mechanical and electrically conductive connection of the PTC component 20 on its two sides facing a respective carrier 14, 16 with the respective carrier 14, 16 or the coating 24, 26 provided thereon.

[0024] To make this connection even more stable, a coating 54, 56 made of metal-containing material can also be provided on the sides 50, 52 of the PTC component 20, which is generally also made of ceramic material, in the manner described above in connection with the carriers 14, 16, so that the solder material 46, 48 creates a connection between the coatings 24, 54 on the one hand and the coatings 26, 56 on the other.

[0025] In Fig. Figure 4 shows alternative configurations for coatings 24, 26 provided on the carriers 14, 16 for providing the respective contact fields in conjunction with the carrier 14 or the contact field 36 provided thereon. Fig. Figure 4a) shows the provision of the coating 24 such that it extends around an end face 58 of the carrier 14, so that the coating 24 provided on the carrier 14 for providing the contact field 36 in the contact field area K surrounds the carrier 14 in a U-shape in the area of ​​its end face 58. Fig. 4b) shows one of the designs of the Fig. 3 corresponding structure in which the material of the coating 24 providing the connection area 42 is provided in the opening(s) 44, but only wets their surface and thus does not completely fill them.

[0026] Each of the two carriers 14, 16 can provide a respective connection area 42 as described in the Fig. 3 and Fig. The connecting areas 42 of the two supports 14, 16 are preferably identical in their design. In principle, the connecting areas 42 of the two supports 14, 16 could be designed differently from each other.

[0027] With regard to the Fig. 5 and Fig. 6. Non-inventive embodiments are described. Thus, the Fig. 5 in conjunction with the carrier 14 represents an embodiment in which neither the carrier 14 nor the PTC component 20 is coated with metallic or metal-containing material prior to the application of the soldering material 46. In the illustrated embodiment, the soldering material 46 is applied directly to the carrier 14 in the PTC component connection area V and on an edge area to create the contact field 36, which in this embodiment is directly provided by the soldering material 46, as well as the connection area 42, and is melted during the induction soldering process and subsequently cooled.

[0028] At the in Fig. In the embodiment shown in Figure 6, which can be used particularly when the carrier(s) 14, 16 themselves are made of electrically conductive material, such as metal, aluminum, steel, copper, or the like, neither the carrier 14 nor the PTC component 20 has a coating of metallic or metal-containing material applied to it. The solder material 46 is located between the carrier 14 and the PTC component 46 on the side 28 of the carrier 14 facing the PTC component 20, essentially only in the PTC component connection area V. Electrical contact can be made at any desired location on the metal-based carrier 14. The previously described use of a solder material fitting for supplying the solder material 46 is particularly suitable for this embodiment.

[0029] It was also with reference to the Fig. 5 and Fig. 6 pointed out that of course a corresponding configuration can also be provided in conjunction with the carrier 16 not shown therein.

[0030] In a further alternative embodiment, for example, a coating 54, 56 of metallic or metal-containing material could be provided on one or both sides 50, 52 of the PTC component 20 facing a respective carrier 14 or 16, while no such coating is provided on the respective associated carrier 14 or 16. The solder material 46 or 48 can then be provided on the respective carrier 14 or 16 or on the coating 54, 56 provided on the PTC component 20 in the manner described above, or can be positioned as a solder material form between a respective carrier 14, 16 and the PTC component 20.

[0031] The previously described method for manufacturing the PTC heating element achieves a simple structure using an easy-to-implement process. To create the mechanical and electrical connections between the PTC component and the two supports attached to it, only a relatively thin layer of solder material and, optionally, an underlying coating of metallic or metal-containing material is required. The overall thickness of the material layers forming the connection is comparatively thin, which, further enhanced by the fact that these material layers are excellent thermal conductors, results in good heat dissipation from the PTC heating element. The supports, preferably made of ceramic or metal material, are also good thermal conductors, contributing to high efficiency.

[0032] Another significant advantage of the PTC heating element 10 produced using the inventive method is that, as the Fig.Figure 3 shows that the PTC component is positioned relative to the two supports 14 and 16 such that the PTC component connection area V does not overlap with the respective contact field area K. This means that the PTC component 20 in the PTC heating element 10 also does not overlap with the contact fields and is preferably arranged at a distance from them. This allows the entire area of ​​the supports 14 and 16 in contact with the PTC component 20 to be used for transferring heat to a medium to be heated. This prevents heat buildup inside the sandwich-like structure and results in a high efficiency for a PTC heating element constructed in this way, since heat dissipation into areas that are not actually used for heating a medium is largely prevented.

[0033] It should be noted that various variations are possible with the previously described procedure for manufacturing a PTC heating element. For example, it is possible to arrange several PTC components between two supports using the aforementioned procedure. For this purpose, the frame could, for instance, have an opening to accommodate each PTC component positioned between the two supports. Furthermore, the two contact fields for electrically connecting the PTC component could be located on one of the two supports, while the other support lacks such a contact field. For example, the two contact fields could be located on the short sides of one of the two rectangular supports, which are spaced apart from each other.To prevent an electrical short circuit through the solder material providing such contact fields on one of the two carriers, this material can have an interruption in a length between the two contact fields in the PTC component connection area, thus forcing a current flow through the PTC component. In this embodiment, the two carriers are preferably made of electrically insulating material, such as ceramic material, to also prevent an electrical short circuit across the carriers.

Claims

[1] Method for manufacturing a PTC heating element, wherein the PTC heating element (10) comprises at least one PTC component (20) and a support (14, 16) firmly connected to the at least one PTC component (20) on at least one side (50, 52), wherein at least one support (14, 16) to be connected to the at least one PTC component (20) is designed as a plate and is constructed with electrically insulating material, wherein at least one contact field (36) is provided on at least one support (14, 16) constructed with the electrically insulating material in the method, and wherein the method comprises the measures: a) Arranging solder material (46, 48) between at least one side (50, 52) of at least one PTC component (20) to be firmly connected to a support (14, 16) and a support to be connected to the at least one PTC component (20) on this side (50, 52), wherein the measure a) comprises, prior to arranging the solder material (46, 48), providing a coating (24, 26, 54, 56) of metal material on a side of at least one support (14, 16) to be positioned facing the at least one PTC component (20). b) Melting the solder material (46, 48) and thereby connecting the at least one PTC component (20) with at least one support (14, 16), characterized by , - that measure b) includes melting the solder material (46, 48) by induction soldering, - that at least one contact field (36) is provided on a side (38, 40) of the carrier (14, 16) facing away from the at least one PTC component (20) by means of the coating (24, 26) provided on at least one carrier (14, 16) which is constructed with the electrically insulating material, - that a connection area (42) is formed for connecting an area of ​​the coating (24, 26) provided on the side of this carrier (14, 16) facing the at least one PTC component (20) with an area of ​​the coating (24, 26) provided on the side (38, 40) of this carrier (14, 16) facing away from the at least one PTC component (20), and - that the connection area (42) is provided by the coating (24) extending around an end face (58) of this carrier (14, 16) or by material of the coating (24) arranged in one or more openings (44) formed in the carrier (14, 16). [2] Method according to claim 1, characterized by , that in measure a) the solder material (46, 48) is applied to at least one side (50, 52) of the at least one PTC component (20) to be connected to a carrier (14 16), or / and that in measure a) the solder material (46, 48) is applied to at least one carrier (14, 16) to be connected to the at least one PTC component (20). [3] Method according to claim 2, characterized by , that in measure a) the soldering material (46, 48) is applied in a flowable state, preferably by screen printing. [4] Method according to any of the preceding claims, characterized by , that in measure a) the solder material (46, 48) is arranged by positioning a solder material shape between the at least one PTC component (20) and the at least one carrier (14, 16) to be connected to it. [5] Method according to any of the preceding claims, characterized by, that the measure a) includes providing a coating (24, 26, 54, 56) of metal material on at least one side of the at least one PTC component (20) to be connected to a support (14, 16) before the soldering material (46, 48) is applied. [6] Method of one of the preceding claims, characterized by , that the coating (24, 26, 54, 56) is provided by applying a flowable, metal-containing coating material, preferably by screen printing, and curing the coating material on at least one side (50, 52) of the at least one PTC component (20) to be connected to a support (14, 16) or / and at least one support (14, 16) to be connected to the at least one PTC component (20). [7] Method according to claim 6, characterized by that the coating material contains aluminum and / or silver. [8] Method according to claim 6 or 7, characterized bythat the coating material is heated and cured at a temperature in the range of 600-900 °C. [9] Method of one of the preceding claims, characterized by that the electrically insulating material is ceramic material.

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