EP2044599B1 - Resistor assembly - Google Patents

Abstract

A first preferred embodiment of the invention discloses a resistor assembly comprising resistor elements (21, 22, 23), the first electrodes of which (201) are conductively interconnected by means of a flexible conductive connection element (12, 14) that is curved. The curve of the connection element is modified in the regions situated between two adjacent resistor elements. A second preferred embodiment of the invention discloses a resistor assembly comprising resistor elements (21, 22, 23) that are interconnected by a flexible connection element. Each resistor element (21, 22, 23) has an arrangement of slit-type cavities (221, 222).

Description

A heating device with granules of PTC material, which are distributed in a binder, is from the document DE 3107290 A1 known. Out DE 8309023 U1 is known a flexible heater in tape form. Out US 4,072,848 a resistor arrangement is known, consisting of resistance elements, each having a first and a second electrode, wherein the first electrodes are conductively connected to each other by means of a flexible first electrical connection element.

An object to be solved is to provide a resistor assembly suitable for efficiently dissipating heat to a curved surface or detecting a physical quantity of a curved surface object.

The object is solved by the invention according to claim 1.

The second electrodes of the resistance elements are preferably conductively connected to each other according to claim 3.

The connecting elements are also referred to below as supply lines.

The measured between two adjacent resistance elements length of the respective electrical connection element exceeds the minimum distance between these resistance elements. Thus, it is possible to prevent mechanical stresses of the electrical connection elements in the case of bending loads of the resistance arrangement.

The resistance elements are preferably fixedly connected to a first flexible carrier film. You can also be firmly connected to a second flexible carrier film. The resistive elements are preferably arranged between the flexible carrier foils. The features mentioned below in connection with a flexible carrier foil apply in a preferred variant for both flexible carrier foils.

The flexible carrier foil may be a metal foil. However, the flexible carrier film may also comprise an elastic material in which the respective electrical connection element is embedded in the form of a curved conductor track.

Between the flexible electrical connection elements, a flexible insulating layer may be arranged, which at least partially fills the intermediate spaces formed between the resistance elements in the lateral direction.

The resistance elements and the flexible electrical connection elements are embedded in an advantageous variant in a flexible substrate, wherein they are preferably cast in the substrate. The preferably rubbery substrate may contain silicone rubber. Other rubbery, preferably electrically insulating materials come as a material for the substrate into consideration. In particular are for materials suitable, which have a high thermal conductivity.

To achieve high thermal conductivity, a filler having a higher thermal conductivity than the rubbery base material can be added to a flexible, rubbery material. Preferably for electrically non-conductive or poorly conductive substances such. As SiC, MgO, ceramic or metal oxide used.

The resistive elements may be disposed between two flexible substrates, the substrates preferably being equated with the above-mentioned carrier foils.

In an advantageous variant, the resistance elements, the flexible electrical connections and the carrier foils are embedded in a flexible substrate, preferably encapsulated.

The respective electrical connection element can be integrated in the substrate. The connecting element is preferably realized as a recessed in the flexible substrate, curved conductor track. The connecting element may comprise, for example, a metal strand. The respective electrical connection element may alternatively be realized as a laminated metal layer which is arranged on the surface of the respective flexible carrier film. The respective carrier film can, for. Example, a copper-clad polyimide film or another flexible film which is electrically conductive or comprises an electrically conductive layer.

The minimum distance between the flexible electrical connectors in between the resistor elements lying areas may be smaller than the height of the resistance elements. The distance between the flexible electrical connections in such areas may also be greater than the height of the resistance elements.

In a variant, the second electrodes of the resistance elements can be electrically connected by an electrically conductive surface which touches the resistance arrangement, but is not part of this arrangement.

In the respective flexible carrier film recesses may be formed for receiving resistor elements.

The resistor arrangement preferably comprises similar resistor elements. At least one major surface of the respective resistive element may comprise an array of slot-like depressions.

Hereinafter, advantageous embodiments of the resistor arrangement will be explained.

The resistor arrangement represents a planar structure whose length, measured in at least one lateral direction, is preferably substantially zero. B. by at least a factor of 3 - is greater than its thickness. The flexible connecting element is preferably a flat substrate carrying the resistance elements.

The resistance elements are preferably plate-shaped or flat. The resistance elements are preferably ceramic elements, each comprising a solid, preferably solid, rigid ceramic body. The material of the ceramic body preferably has PTC properties and preferably contains BaTiO ₃ . PTC stands for Positive Temperature Coefficient.

The ceramic body is preferably formed as a resistive layer disposed between a first and a second electrode. The electrodes are preferably arranged on the main surfaces of the resistance element. The second electrode is electrically isolated from the first electrode. The electrodes are preferably barrier-degrading.

Although in an advantageous variant each resistance element is rigid in itself, the resistance arrangement with the deformable electrical connections is flexible. This has the advantage that it can be positively applied to an arbitrarily shaped, even curved surface.

In an advantageous variant, the resistance elements are provided as heating elements. The resistor assembly is preferably a heater. In another variant the resistance elements are provided as sensor elements. Sensor elements are for detecting a physical quantity such. B. temperature suitable. The resistor arrangement in this case is a sensor device.

The resistor assembly can be made, for example, in the following method.

Electrode provided resistive elements are provided. These are connected to each other by attachment to at least one electrically conductive foil or at least one metal mesh. An electrically conductive film is understood as meaning a metal foil or a foil which has an electrically conductive layer which is arranged on a non-conductive carrier. Preferably, first major surfaces of the resistive elements with a first film and their second major surfaces with a second film z. B. connected by soldering or gluing.

The spaces between the resistance elements are at least partially encapsulated with an electrically insulating material, which remains elastically deformable (flexible) after curing. In addition, a layer of flexible material may be applied to at least one of the conductive foils or metal braids to form a flexible substrate. Preferably, the assembly comprising the conductive foils and the resistive elements attached thereto is encapsulated in the flexible material. The flexible material is preferably electrically insulating.

The electrically conductive film is preferably preformed before embedding in the flexible material such that the between the resistance elements arranged electrical connections to the minimum distance between these resistance elements are extended. In particular, the electrical connections can be structured in cross-section with respect to their altitude and in particular be curved. The electrical connections may also have steps or form at least part of a loop.

Curved electrical connection elements can be achieved by forming recesses in the electrically conductive film. The depressions can each serve to receive a resistance element. Also between the resistor elements z. B. groove-shaped recesses are formed, which contribute to the mechanical relief of the electrical connections when bending the resistor assembly.

The electrically conductive foil or the metal braid is - preferably soldered or glued to externally accessible electrical connections - preferably before embedding in the flexible material. The arrangement of interconnected resistor elements with the terminals is then inserted into a mold and connected to the electrically insulating material such. B. silicone rubber shed. To avoid trapped air, it can then be evacuated.

The finished after curing of the flexible material resistor assembly can now be removed from the mold. It is flexible and can be used in particular for heating objects, wherein the resistance arrangement can be applied positively to a curved surface.

In a further method, a possibly not yet cured carrier substrate (eg silicone film) is provided, in which a wire mesh or another structured conductor track is embedded, which has curvatures. This substrate is connected to a resistive substrate which does not comprise isolated resistive elements. The connection of the substrates takes place in such a way that the curved conductor track touches the main surface of the resistance substrate in the regions provided as resistance elements.

After curing of the material of the carrier substrate, the resistor substrate can be separated into a plurality of resistive elements by cutting or sawing. The separation is carried out so that only the resistor substrate is cut through, wherein the carrier substrate is only cut without damage to the embedded therein conductor track. This can be done using a hard pad.

This results in a composite comprising on one side electrically and mechanically interconnected resistance elements. A two-sided electrical and mechanical connection of the resistance elements is also possible. In this case, a main surface of the composite still not connected to any substrate is connected to a second carrier substrate in a similar method, wherein the second carrier substrate preferably has the properties of the first carrier substrate.

Between the first and the second carrier substrate, an air gap may be provided which prevents a short circuit between the carrier substrates. The gaps which are present between the carrier substrates and the resistance elements, but can also with an electrically insulating, flexible, highly thermally conductive material such. B. silicone rubber be filled. For this purpose, the intermediate spaces formed between the resistance elements are preferably poured out before connecting the composite to the second carrier substrate with this material.

The resistance elements may have arranged on their major surfaces, preferably slot-like depressions. These recesses are preferably arranged on at least one main surface of the resistance elements. The electrode layers also cover the surface of these recesses.

• Figur 1A im Querschnitt ein beispielhaftes Widerstandselement;
• Figur 1B, 1C im Querschnitt Widerstandselemente auf einer metallkaschierten Trägerfolie;
• Figur 1D im Querschnitt die Anordnung gemäß Figur 1C, die in ein Substrat eingebettet ist;
• Figur 1E eine Widerstandsanordnung mit Widerstandselementen gemäß Fig. 1A, die teilweise in ein elastisch verformbares Substrat eingebettet sind;
• Figur 1F eine Widerstandsanordnung mit Widerstandselementen gemäß Fig. 1A, die zwischen zwei elastisch verformbaren Substraten angeordnet sind;
• Figur 2 im Querschnitt eine Widerstandsanordnung, bei der elektrische Verbindungselemente zur Kontaktierung von ersten und zweiten Elektroden der Widerstandselemente im Substrat eingebettet sind;
• Figur 3 im Querschnitt die Widerstandsanordnung gemäß Figur 2, die an eine gekrümmte Oberfläche angepasst ist;
• Figur 4 im Querschnitt die Widerstandsanordnung gemäß Figur 5;
• Figur 5 Draufsicht auf eine flächige Widerstandsanordnung;
• Figur 6 eine Widerstandsanordnung mit geschlitzten Widerstandselementen und zwei elastisch verformbaren Substraten;
• Figur 7A elektrisch miteinander verbundene geschlitzte Widerstandselemente;
• Figur 7B eine Widerstandsanordnung mit in einem Substrat eingebetteten, elektrisch miteinander verbundenen geschlitzten Widerstandselementen.

The specified resistor arrangement and the method for their preparation will now be explained with reference to schematic and not to scale figures. Show it:

• Figure 1A in cross-section an exemplary resistance element;
• FIG. 1B, 1C in cross-section resistance elements on a metal-laminated carrier film;
• FIG. 1D in cross-section, the arrangement according to Figure 1C embedded in a substrate;
• Figure 1E a resistor arrangement with resistor elements according to Fig. 1A partially embedded in an elastically deformable substrate;
• Figure 1F a resistor arrangement with resistor elements according to Fig. 1A which are arranged between two elastically deformable substrates;
• FIG. 2 in cross-section, a resistor arrangement in which electrical connection elements for contacting first and second electrodes of the resistive elements are embedded in the substrate;
• FIG. 3 in cross section, the resistor arrangement according to FIG. 2 which is adapted to a curved surface;
• FIG. 4 in cross section, the resistor arrangement according to FIG. 5 ;
• FIG. 5 Top view of a planar resistor arrangement;
• FIG. 6 a resistor array with slotted resistive elements and two elastically deformable substrates;
• FIG. 7A electrically connected slotted resistor elements;
• FIG. 7B a resistor arrangement with embedded in a substrate, electrically interconnected slotted resistor elements.

In Figure 1A For example, an exemplary resistive element 21 with a rigid body 20 is shown, on the major surfaces of which electrodes 201, 202 are arranged. The resistance elements 21, 22, 23 shown in the following figures are preferably identical.

The resistive elements 21, 22, 23 are mounted on a substrate 1, the carrier sheet 11 z. B. comprises polyimide. The substrate 1 has a metal lamination arranged on the carrier foil-the metal layer 12-which is too the resistance elements is turned ( Fig. 1B ). The attachment can be done by soldering or gluing.

The metal-laminated carrier film 11 is preferably as in Figure 1C shown preformed so that it has recesses for receiving resistor elements 21, 22, 23. Through these recesses curved sections 41 of the metal layer 12 come about, which are arranged between two successive resistance elements. By means of the metal layer 12, which has curved portions, the flexible curved electrical connecting element is realized.

The length of the curved portions 41 is greater than the minimum distance between these resistance elements. The preforming of the metal-clad carrier foil 11 can take place before or after the mounting of the resistance elements 21, 22, 23.

The in the FIGS. 1B, 1C can also be replaced by a composite of a substrate and an electrically conductive layer, shown metal-clad carrier sheet 11. The metal layers 12, 14 can each be replaced by a metal braid. It is always important that when bending the resistor assembly of a bending stress resulting under the mechanical stress can be prevented. This is possible because a structured and therefore longer electrical line compared to a straight line when bending can be relieved to a greater extent mechanically.

In the FIG. 1D is the one in the Figure 1C shown arrangement which is partially embedded between an electrically insulating base layer 1 a and an insulating layer 10. Preferably, the layers 1a, 10 comprise the same Material. They can be laminated, glued or produced by a casting process.

The base layer 1a can also be dispensed with, see Figure 1E , When in the Figure 1C As shown, the spaces between the resistive elements are partially filled with an insulating material. The elastically deformable substrate 1, in which the resistance elements 21, 22, 23 are partially embedded, is in this case formed by the layers 10, 11.

The substrate 1, in which the resistance elements are partially embedded and the electrical connection element (the metal layer 12) is integrated, is formed by the base layer 1a, the carrier foil 11 and the insulating layer 10 in the variant according to FIG. The substrate 1 may further as in the variants according to the Fig. 1F and 2 a second carrier film 13 include. The carrier film 13 preferably has the same properties as the carrier film 11.

The top of the in Fig. 1E As shown in FIG Figure 1F indicated, be connected to a possibly preformed, metal-clad carrier sheet 13. In the variant according to the Figure 1F the substrate 1 is formed by the carrier films 11, 13 and the insulating layer 10. The metal-laminated carrier films 11, 13 can be considered as two elastically deformable substrates, between which the resistance elements are arranged.

Instead of metal-laminated carrier films 11, 13, films of a conductive elastic material can be used in all embodiments.

The substrate 1 may further as in the variant according to Fig. 2 a cover layer 1b.

In the in Fig. 2 In the variant shown, a second electrical connection element, which connects all the second electrodes of the resistance elements to one another in a conductive manner, is realized by means of the second metal layer 14. The second metal layer 14 is preferably formed as a metal lamination of the second carrier film 13. The metal lamination of the carrier film, ie the metal layer 14, is turned inwards, that is to say to the resistance elements. The metal layer 14 connects the second electrodes of the resistive elements.

The first metal layer 12 is connected to a first electrical connection 31 and the second metal layer 14 is connected to a second electrical connection 32 of the resistor arrangement. The terminals 31, 32 are accessible from the outside and can, for. B. connected to a plug connection. The comments made in connection with the carrier film 11 and the metal layer 12 also apply to the in the FIGS. 2, 3 shown second carrier film 13 and the associated metal layer 14th

An arrangement formed by the resistance elements 21, 22, 23 and their electrical connections is shown in FIG Fig. 2 completely embedded in the substrate 1. So that the metal layers 12 and 14, which are subjected to different potentials, do not touch one another, an insulating layer 10 is arranged between them.

In the FIG. 3 is the heating arrangement according to the FIG. 2 shown attached to a curved, in the FIG. 3 Not shown surface is adapted.

In the FIG. 4 are the resistance elements 21, 22, 23 by means of a conductive electrical connection element such. B. a preformed metal foil or metal wire conductively connected together. The arrangement, which is formed by the resistance elements 21, 22, 23 and their electrical connections, is cast in the substrate 1.

It is advantageous if at least one main surface of the substrate 1 is planar. Preferably, both main surfaces of the substrate 1 are planar.

The in the FIGS. 1A to 4 The resistor arrangement shown may be in the form of a flexible band having a one-dimensional array of resistive elements 21, 22, 23.

In FIG. 5 is a planar resistor array, ie a resistor array with a two-dimensional array of resistive elements, shown. Such an arrangement arises after cutting through a resistive substrate, which initially comprises non-isolated resistive elements 21, 22, 23, along the predetermined dividing lines, wherein the carrier substrate 1 is not cut through.

The resistance elements shown in the figures explained above can, as in Fig. 6 to 8 be educated.

In FIG. 6 a resistor array is shown with resistive elements having recesses 221, 222 disposed on their major surfaces. The first recesses 221 are on a first major surface (top) of a resistive element and the second recesses 222 on its second main surface (bottom) arranged. The electrode layers 201, 202 also cover the surface of these recesses.

The depressions 221, 222 are preferably filled with a filling material 8, which has a better thermal conductivity than the ceramic body of the resistance element. The gap 7 between two resistance elements is preferably also filled with an elastically deformable filler.

The second recesses 222 are laterally offset from the first recesses 221. The depth of the recesses may be about half or more than half the thickness of the ceramic body.

The resistance elements are mechanically connected to one another by means of elastically deformable substrates 81, 82. Each substrate 81, 82 has an insulating layer 811, 821. Each substrate 81, 82 also has a conductive layer 812, 822 formed on the insulating layer 811, 821, e.g. B. applied as a Metallkaschierung and turned to the resistive elements. The first electrode layers 201 of the resistive elements are conductively connected to each other by means of the conductive layer 812 and the second electrode layers 202 of the resistive elements by means of the conductive layer 822. The layers 812, 822 are electrical connection elements which, like the metal layers 12, 14, are flexible and curved. The curvature of the fasteners is in FIG. 6 Not shown. The layers 812, 822 may be metal meshes or metal foils, which are preferably preformed.

FIG. 7A shows an arrangement of resistive elements whose first electrode layers 201 are electrically connected to one another by means of an electrical connection element 91 and their second electrode layers 202 are connected to one another by means of an electrical connection element 92.

The connecting elements 91, 92 may be metal braids or metal foils, which are preformed such that the length of the connecting element is greater than the distance between the resistance elements to be connected to one another. The first electrode layers 201 are conductively connected to an electrical terminal 31, which is accessible from the outside. The second electrode layers 202 are conductively connected to an electrical terminal 32, which is also accessible from the outside. The embedded in a substrate 81 heating arrangement according to FIG. 7A is in FIG. 7B presented.

LIST OF REFERENCE NUMBERS

1, 81

flexible substrate

1a

base layer

1b

topcoat

10

insulating

11, 13

support film

12, 14

metal layer

20

body

201, 202

Electrodes of the resistive elements

21, 22, 23

resistive elements

221, 222

wells

31, 32

electrical connections

41

curved portions of the metal layer 12

7

gap

8th

filling compound

81, 82

elastically deformable substrate

812, 822

conductive layer

811, 821

insulating layer

91, 92

electrical connection element

Claims (14)

1. Resistor assembly

   - comprising resistor elements (21, 22, 23) each having a first electrode (201) and a second electrode (202),

   - wherein the first electrodes (201) are conductively connected to one another by means of a flexible first electrical connection element (12, 91),

   - characterized in that the first electrical connection element (12, 91), in the case of a rectilinear arrangement of the resistor elements (21, 22, 23), has a curved section (41) between two adjacent resistor elements (21, 22, 23) and the length of the curved section (41) is greater than the distance between the two adjacent resistor elements (21, 22, 23).
2. Resistor assembly according to Claim 1,

   - wherein the resistor elements (21, 22, 23) are fixedly connected to a first flexible carrier film (11).
3. Resistor assembly according to Claim 1 or 2,

   - wherein the second electrodes (202) are conductively connected to one another by means of a flexible second electrical connection element (14, 92), wherein the second electrical connection element (14, 92), in the case of a rectilinear arrangement of the resistor elements (21, 22, 23), has a curved section (42) between two adjacent resistor elements (21, 22, 23) and the length of the curved section (42) is greater than the distance between the two adjacent resistor elements (21, 22, 23).
4. Resistor assembly according to Claim 3,

   - wherein a flexible insulation layer (10) is arranged between the flexible electrical connection elements (12, 14, 812, 822, 91, 92).
5. Resistor assembly according to Claim 3 or 4,

   - wherein the resistor elements (21, 22, 23) are fixedly connected to a second flexible carrier film (13).
6. Resistor assembly according to any of Claims 3 to 5,

   - wherein the flexible electrical connection elements (12, 14, 812, 822, 91, 92) are embedded in a flexible substrate (1, 81),

   - wherein the resistor elements (21, 22, 23) are at least partially embedded in the flexible substrate (1, 81).
7. Resistor assembly according to Claim 5,

   - wherein the resistor elements (21, 22, 23), the flexible electrical connection elements (12, 14, 812, 822, 91, 92) and the carrier films (11, 13) are embedded in a flexible substrate (1, 81).
8. Resistor assembly according to any of Claims 3 to 7,

   - wherein the distance between the flexible electrical connection elements (12, 14, 812, 822, 91, 92) in the regions lying between the resistor elements (21, 22, 23) is less than the height of the resistor elements (21, 22, 23).
9. Resistor assembly according to any of Claims 3 to 7,

   - wherein the distance between the flexible electrical connection elements (12, 14, 812, 822, 91, 92) in the regions lying between the resistor elements (21, 22, 23) is greater than the height of the resistor elements (21, 22, 23).
10. Resistor assembly according to any of Claims 2 to 9,

    - wherein a laminated metal layer is arranged on the first flexible carrier film (11), the first flexible electrical connection element (12, 812, 91) being formed by said metal layer.
11. Resistor assembly according to any of Claims 2 to 10,

    - wherein depressions for receiving resistor elements (21, 22, 23) are formed in the first flexible carrier film (11).
12. Resistor assembly according to any of Claims 5 to 11,

    - wherein a laminated metal layer is arranged on the second flexible carrier film (13), the second flexible electrical connection element (14, 822, 92) being formed by said metal layer.
13. Resistor assembly according to any of Claims 6 to 9,

    - wherein the flexible electrical connection elements (12, 14, 812, 822, 91, 92) are in each case realized as a curved conductor track incorporated in the flexible substrate (1).
14. Resistor assembly according to any of Claims 1 to 13,

    - wherein at least one main area of the respective resistor element (21, 22, 23) has an arrangement of slot-like depressions (221, 222).

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