Sensor Arrangement and Method for Producing a Sensor Arrangement

Abstract

A sensor arrangement and a method for producing a sensor arrangement are disclosed. In an embodiment, the sensor arrangement for a temperature measurement includes a sensor element with at least one electrode and at least one contacting element, wherein the contacting element is arranged and configured for wireless contacting of the sensor element.

Claims

1-13. (canceled)

14. A sensor arrangement for a temperature measurement comprising: a sensor element with at least one electrode; and at least one contacting element, wherein the contacting element is arranged and configured for wireless contacting of the sensor element.

15. The sensor arrangement according to claim 14, wherein the contacting element has a first bearing area and a second bearing area, and wherein at least one of the first bearing area or the second bearing area is arranged at least partially on an outer area of the sensor element.

16. The sensor arrangement according to claim 15, wherein the other one of the first and second bearing areas is arranged and configured for connecting the sensor element to a printed circuit board.

17. The sensor arrangement according to claim 15, wherein the first and second bearing areas form a horizontally running region of an upper side and/or an underside of the contacting element, and wherein the bearing areas are connected to another by a vertically running region of the contacting element.

18. The sensor arrangement according to claim 14, wherein the contacting element is designed in a stepped form.

19. The sensor arrangement according to claim 14, wherein the contacting element is designed in a wavy form.

20. The sensor arrangement according to claim 14, wherein the contacting element comprises a metal bracket.

21. The sensor arrangement according to claim 14, wherein the sensor element has an upper side, and wherein the contacting element is at least partially connected to the upper side.

22. The sensor arrangement according to claim 21, wherein the contacting element is sintered on the upper side.

23. The sensor arrangement according to claim 14, wherein the sensor element has an underside, and wherein a further contacting element is at least partially arranged on the underside of the sensor element.

24. A method for producing a sensor arrangement, the method comprising: producing NTC sheets to form a ceramic main body; sintering stacked, pressed and decarburized green sheets; applying Ni/Ag thin-film electrodes to the main body on both sides to form a sensor element; and applying at least one contacting element to an outer area of the sensor element.

25. The method according to claim 24, further comprising contacting the sensor element to form a printed circuit board by Ag sintering.

26. The method according to claim 24, wherein contacting the sensor element by the contacting element and connecting the sensor element to a printed circuit board are performed in one processing step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described below should not be regarded as true to scale. Rather, for better representation, individual dimensions may be shown as increased or reduced in size or even distorted.

[0035] Elements that are the same as one another or perform the same function are provided with the same designations.

[0036] FIG. 1 shows a sensor arrangement,

[0037] FIG. 2 shows the sensor arrangement as shown in FIG. 1 in a side view,

[0038] FIG. 3 shows the sensor arrangement as shown in FIG. 2 according to a further exemplary embodiment,

[0039] FIG. 4 shows a sensor arrangement mounted on a DCB board.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0040] FIG. 1 shows a sensor arrangement 10. FIG. 2 shows the sensor arrangement 10 in side view. The sensor arrangement lo has a sensor element 1. The sensor element 1 (sensor 1) preferably consists of a chip NTC thermistor. The chip NTC thermistor is produced on the basis of perovskites in the system YCaCrAlO with various dopings or on the basis of spinels in the system NiCoMnO with various dopings. The sensor element 1 has in particular a ceramic main body 7. The ceramic main body 7 is produced on the basis of the aforementioned structures. In addition, the sensor element 1 may have a further ceramic reinforcement or a carrier (not explicitly shown). The chip NTC thermistor 1 may either be produced directly by pressing of granular material or be built up from ceramic sheets.

[0041] Electrodes 2, 3 are applied to the upper side 5 and underside 6 of the sensor 1 by means of screen printing or thin-film technology, such as, for example, sputtering.

[0042] In the application of the electrodes, a distinction can be made between thin-film and thick-film technology. The production of thin-film electrodes may be performed by sputtering or vapor deposition. In this case, in a first embodiment the base electrode consists of one layer (for example, a nickel layer, which may comprise fractions of vanadium, or a copper layer) or in a second embodiment of two layers (for example, Cr/Ni, Ti/Ni or Ni/Cu), which likewise may comprise fractions of vanadium. The base electrode may be protected by a covering layer consisting of an oxidation-inhibiting metal. In the case of a connection by means of Ag sintering with finely dispersed silver pastes, a silver covering electrode is advantageous. The thickness of the base electrode is less than 10 m, preferably less than 3 m, ideally less than 0.5 m. The thickness of the covering electrode may be up to 1 m, in exceptional cases up to 20 m.

[0043] The production of thick-film electrodes may be performed by a screen printing process with subsequent firing. The pastes used may contain Ag or Au or any admixtures.

[0044] The electrodes 2, 3 areas mentioned aboveapplied to the upper side and underside 5, 6 of the chip NTC thermistor.

[0045] The sensor arrangement 10 has a contacting element 4. Furthermore, the sensor arrangement 10 may also have further contacting elements 4, as described in connection with FIG. 3.

[0046] In particular, the contacting element 4 is arranged on the upper side 5 of the sensor 1. The contacting element 4 lies at least partially on the electrode 2, which is arranged on the upper side 5.

[0047] According to this exemplary embodiment, the contacting element 4 takes the form of a metal bracket. In particular, the contacting element 4 is designed in a stepped form. However, it is also conceivable to give the contacting element 4 other forms, for example, a curved form of the contacting element 4.

[0048] In any event, the contacting element 4 must have a first bearing area 4a and a second bearing area 4b. The bearing areas 4a, 4b are formed on the same side, for example, an underside, of the contacting element 4. As an alternative to this, the bearing areas 4a, 4b may also be formed on different sides, that is to say the upper side and the underside of the contacting element 4.

[0049] In this exemplary embodiment, the bearing areas 4a, 4b are designed as horizontal portions of the underside of the contacting element 4. The bearing areas 4a, 4b are connected to one another by a vertical web 4c. The upper side, opposite from the underside of the contacting element 4, is designed correspondingly. That is to say that the upper side of the contacting element also has two horizontal regions and a vertical web arranged in between.

[0050] The first bearing area 4a lies on the upper side 5 of the sensor element 1. In particular, the first bearing area 4a covers at least partially the electrode 2 arranged on the upper side 5. The contacting element 4 is pressurelessly sintered on the upper side 5 of the chip NTC thermistor with an Ag paste. There is alternatively also the possibility of mounting the contacting element 4, for example, the metal bracket, by means of a soldering process or by adhesive bonding.

[0051] The second bearing surface 4b lies, for example, on a printed circuit board or mother board or a DCB board 11 (see FIG. 4). The second bearing surface 4b may lie on an electrode pad 12a, 12b of the DCB board (FIG. 4).

[0052] The contacting of the sensor 1 with respect to the DCB board 11 or the mother board may be performed by means of Ag sintering, soldering or adhesive bonding, the chip NTC thermistor 1 being placed onto one electrode pad and the contacting element 4 being placed onto a further electrode pad. The contacting of the sensor 1 by means of the contacting element 4 is consequently provided in one process step together with the mounting of the further components. In this exemplary embodiment, the chip NTC thermistor with the contacting element 4 consequently consists substantially of a chip NTC thermistor, which is contacted by a metal bracket on the upper side 5. Apart from the contacting with respect to the board, the contacting element 4 serves as protection for the chip NTC thermistor 1 during the Ag pressure sintering.

[0053] For particularly closely toleranced resistances at nominal temperature, the resistance of the individual components can be set by an additional trimming process. In this case, ceramic material or electrode material is partially removed, for example, by laser cutting, grinding or sawing, in such a way that the resistance is adapted by changing the geometry.

[0054] The mounting of the metal bracket is performed after the adaptation of the resistance. The sensor 1 mayas described abovebe sintered under pressure onto the mother board/the DCB board. Contacting of the sensor 1 with respect to the conductor tracks is also possible furthermore by adhesive bonding or soldering. The direct contacting in one process step means that further contacting, for example, by bonding, is no longer required. The chip NTC thermistor 1 can accordingly be provided with the metal bracket in a wireless mounting operation.

[0055] The chosen structural form makes it possible for a component to be processed with small electrical resistance tolerances. At the same time, the mechanical stability of the thermistor is increased by the design with the metal bracket, in that the chip NTC thermistor itself is protected during the process of the pressure sintering. The pressure sintering of the component is thereby made possible without inducing any damage such as micro cracks or the like, or even bringing about a rupturing of the component.

[0056] There follows a description of the production of the sensor arrangement 10 by way of example.

[0057] In a first step, the production of NTC powder is performed. This comprises initial weighing, wet pre-grinding, drying, screening, calcining, wet after-grinding, drying and screening.

[0058] In a further step, the production of NTC sheets is performed. After that, the stacking and pressing of the green sheets is performed. This is followed by decarburizing of the stacked and pressed green sheets.

[0059] Subsequently, the sintering of the decarburized substrates is performed. In a further step, Ni/Ag thin-film electrodes are applied on both sides, as already stated further above.

[0060] After that, the electrical measuring of the resistances of the individual substrates at nominal temperature is performed. This is followed by the substrates being individually separated into chip NTC thermistors on the basis of the measurement data obtained in advance.

[0061] The resistance of the thermistor may be set on the one hand by means of the sintering parameters/ceramic composition and on the other hand by means of the chip geometry. Before the individual separation of the substrates, their overall resistance at nominal temperature is determined. On the basis of the measurement data obtained in advance, the geometry of the respective chip NTC thermistor is defined.

[0062] The final geometry is produced by a cutting process. In the case of very closely toleranced resistances, a trimming process may be performed for setting the resistance at nominal temperature by partial laser ablation.

[0063] A visual inspection and random control measurement follow. After that, the metal bracket is applied, as described above. In particular, the mounting of the metal bracket is performed after adaptation of the resistance. Lastly, a visual inspection and random control measurement are once again performed.

[0064] FIG. 3 shows a side view of a sensor arrangement 10 according to a further exemplary embodiment.

[0065] As a difference from the sensor arrangement 10 according to FIGS. 1 and 2, the sensor arrangement 10 from FIG. 3 has two contacting elements 4, 4. In this case, one contacting element 4 is arranged such that its first bearing surface 4a rests at least partially on the upper side 5 of the sensor 1. The second bearing surface 4b of this contacting element 4 is designed, for example, for being arranged on a printed circuit board or DCB board 11, in order to contact the sensor 1 (see FIG. 4). In particular, the second bearing area 4b may be arranged on an electrode pad 12b of the DCB board 11, as can be seen from FIG. 4.

[0066] As a difference from the contacting element described in connection with FIGS. 1 and 2, the side leg of the contacting element 4 that is formed by the second bearing area 4b and the opposite horizontal area may for this purpose be formed as thicker (not explicitly shown). In this way, a greater distance, in particular a great height, between the sensor 1 and the printed circuit board can be bridged. For example, the sensor 1 may therefore be made higher here oras in this casebe arranged on a further contacting element 4. As an alternative to making the leg thicker, the vertical web 4c, which connects the bearing areas 4a, 4b, may be made longer, as shown in FIG. 3.

[0067] The further contacting element 4 is arranged such that it's first bearing area 4a at least partially lies on an underside 6 of the sensor 1. In this exemplary embodiment, a third bearing area 8, opposite from the first bearing area 4a, lies, for example, on the printed circuit board or the DCB board 11. The third bearing area 8 is arranged here on the upper side of the contacting element 4. As an alternative to this, a partial region of the first bearing area 4a may also lie on the DCB board 11 or an electrode pad 12a (see FIG. 4). In this case, the partial region of the first bearing area 4a forms a further or second bearing area 4b, which serves for bearing on the DCB board 11.

[0068] The description of the subjects specified here is not restricted to the individual specific embodiments. Rather, the features of the individual embodiments canas far as technically feasiblebe combined with one another in any desired manner.