MXPA97003843A

MXPA97003843A - Temperature sensor with medic resistor

Info

Publication number: MXPA97003843A
Application number: MXPA/A/1997/003843A
Authority: MX
Inventors: Wienand Karlheinz; Schlag Frank; Damaschke Gerhard
Original assignee: Heraeus Sensornite Gmbh
Priority date: 1996-05-24
Filing date: 1997-05-23
Publication date: 1998-04-01

Abstract

An easy-to-manufacture temperature sensor has a measurement resistor with a substrate having an electrically insulating surface and a resistance layer located thereon, the measurement resistor being surrounded by a stable temperature plastic cover serving as the main housing, which, together with the embedded measurement resistor, is surrounded by an additional plastic extrusion coating as an outer housing, in which the wires of the measurement resistor are passed through the main housing and the plastic extrusion coating towards the external, the measuring resistor is suitable for use in durable consumer goods, such as washing machines, dryers and automotive vehicles

Description

TEMPERATURE SENSOR WITH MEASURING RESISTOR BACKGROUND OF THE INVENTION The invention relates to a temperature sensor with a measurement resistor consisting of a substrate with an electrically insulating surface and a resistance layer placed thereon, in which the measurement resistor is surrounded by a temperature plastic cover stable through which the wires of the measuring resistor are passed. From document DT 25 27 739 B2, (patent of EUR No. 4,050,052) a method is known for producing an electrical measurement resistor for a resistance thermometer, in which a thin film of platinum is applied with a temperature coefficient Preferably on a carrier of ceramic material, and the measurement resistor is subsequently provided with a stable temperature cover layer, for example of epoxy resin to make it resistant to thermal and mechanical stresses. Furthermore, the covering layer must offer protection against the diffusion of the gas phase, solid substances coming from the surroundings or against objects that come in contact with the measuring resistor. In addition, the utility model is known. German 89 13 803. 1 a resistance thermometer to measure the temperature of the surface, in which a metal layer temperature sensor is surrounded by a plastic cover through which the wires of the resistance thermometer are passed to the Exterior. The plastic cover is made of a multiple plastic extrusion and is made of epoxy resin. The temperature sensor * is provided for mounting directly on a surface whose temperature will be measured. Furthermore, DE 41 04 674 Rl discloses a temperature sensor, in which the building resistor serving as the sensor is formed by a thin layer resistor of platinum on the front side of a carrier with a plate shape. of ceramic This is enclosed in a tube-shaped, pressure-tight glass housing that is essentially free of tension only at its longitudinal edges, while all remaining smooth surfaces and edge surfaces, as well as the same resistor of the measurement are completely free of contact in relation to the housing. In this way, the carrier can be locked free of vibrations without appreciable deterioration in response behavior. Due to the relatively accurate centering or precise alignment of the carrier in relation to the housing, manufacturing is comparatively expensive. Furthermore, from the German utility model 79 19 142 a thin layer measurement resistor for temperature measurements is known, in which a small ceramic plate is provided as a carrier with a thin plate coating as a resistance layer. , in which the resistance layer has conductive wires-is electrically connected. The thin layer measuring resistor is arranged in a ceramic housing consisting of two halves, in which the halves are fused or bonded to one another on their interface with a binder, and the connecting wires leading out from the Measurement resistor are embedded in the binder. Due to the double shell housing, a precise construction is required.

BRIEF DESCRIPTION OF THE INVENTION An object of the invention is to create * a comparatively simple temperature sensor to produce *, which can be manufactured economically and can be installed in durable consumer goods, such as, for example, washing machines, dryers and temperature regulators in automotive vehicles. The object is achieved, since a cover serves as a main housing, which, together with the embedded measurement resistor, is surrounded by an additional plastic extrusion coating as an outer housing, in which the wires are passed out to the outside. through the plastic extrusion coating.

The robust and simple structure proves to be especially advantageous for a sealed LITHIUM seal against the surrounding atmosphere, so that the sensor can also be used in an aggressive environment. Rdernas, this can be produced economically.

BRIEF DESCRIPTION OF THE VARIOUS VISTRS OF THE DRAWING The above brief description, as well as the detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, modals which are presently preferred are shown in the drawings. However, it must be understood that the invention is not limited to the precise dispositions and insularities shown. In the drawings: The figure shows a cross-sectional top view of a temperature sensor in connection with which the measurement resistor is applied to an SMD structure board; Figure Ib shows a sensor according to Figure 1 in longitudinal section; and Figures 2a and 2b show a temperature sensor with a TO housing or a TOS housing and wire contacts.

DETAILED DESCRIPTION OF THE INVENTION According to FIG. 1, the measurement resistor 1 is arranged at one end 2 of an elongate board 3 and is applied by means of SMD welding (surface mounted device). The measuring resistor is connected to the external wire contacts 8,9 of the temperature sensor by means of wire contacts 6,? and through ribbon drivers 4,5. The measuring resistor * consists of a ceramic substrate in the form of a plate with an electrically insulating surface to which it is applied to the measuring resistor in the form of a thin layer of platinum. As is known from DE 25 27 739 B2, such measurement elements may have, for example, a resistance layer in serpentine form, which, however, will not be described in detail herein. In the top view * in sensor cut-out *, the plastic case 10 which can be a silicone varnish, for example, is recognizable as a main sealing housing, which is penetrated with an opening through which they pass. wires for the part of the board 3 that faces towards the external wire contacts 8,9. The external wire contacts 8,9 are constructed as pins. The main housing consisting of the plastic cover 10 and the board 3, are in turn enclosed by a plastic extrusion liner 13, which can be a thermofixable plastic, in which the external wire connection contacts 8, 9 are projected as pin contacts outside this plastic extrusion liner 13, which seals the board, as well as the measuring resistor. The measuring resistor I is soldered directly to the respective ribbon conductors 4.5 in the board 3 in the area of the wire contacts 6.7. On the basis of the longitudinal section according to Figure Ib, the measurement resistor 1 can be seen in elevation, the substrate 15 of which is constructed as a ceramic part in the form of a plate, which is constructed as an electrically insulating material. less in the surface area facing the resistance layer 16. The resistance layer 16 has the wire contacts 6,7 at their opposite ends, which are respectively directly welded to the ribbon conductors 4.5 on the board 3 in an electrically insulating manner mutually. In this way, for example, the contact wire 6 is electrically and mechanically connected firmly to the ribbon conductor 4 by welding, and the wire contact 7 correspondingly with the ribbon conductor 5. The measurement resistor 1, together with the end 2 of the board 3, are embedded in the plastic cover 10, while this consists of the main housing. The plastic cover 10, as well as a large part of the circuit board 3, are enclosed by plastic extrusion coating 13 as an external housing, which in the end area 18 has an opening for the passage of the conductors for the external wire contacts. , 9 built like pegs. Through the shortening of the circuit board 3, it is possible to position a temperature sensor, for example in a typical semiconductor housing, as subsequently shown in Figures 2a and 2b. Figure 2a illustrates a perspective representation of a temperature sensor according to figures la, Ib, whose plastic extrusion coating 13 is constructed as a TO housing (transistor contour), as it is normally applied in the field of the semiconductor elements. The transistor housings for printed circuit board components are usually designated TO, where the external wire contacts 8, 9 in the area of the connecting surface 20 are constructed in the form of elongated terminals 8 ', 9' which are suitable for welding to ordinary circuit boards. However, it is also possible to insert the terminals 8 ',' into plug sockets to, if necessary, obtain a fast exchange capacity. In addition, FIG. 2b shows a plastic extrusion coating 13, which is constructed with a so-called SOT housing (small contour transistor). Such SOT housings serve to equip panels printed circuit in SMD technology, in which the contactors directed outwards 8,9 with their welding surfaces 3", 9" can be- directly welded on the contact surfaces of the circuit boards printed SMD technology. Such SOT housings are especially suitable for binding purposes. It will be appreciated by those skilled in the art that changes can be made to the modalities described above without going beyond the inventive broad concept thereof. It is understood, therefore, that this invention is not addressed to the particular modes described, <; * not that it is designed to cover the modifications within the spirit and scope of the present invention, as defined by the appended claims.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. - A temperature sensor consisting of a measurement resistor 1 comprising a substrate with an electrically insulating surface, a resistance layer located on said surface and conductors extending therefrom, the measurement resistor is surrounded by a cover 10 of stable temperature plastic through which the conductors of the measurement resistor pass, the cover 10 serves as a main housing which together with the measurement resistor l are surrounded by an additional plastic extrusion coating 13 as a housing outside, in which the conductors 4,5 pass outwards through the plastic extrusion liner 13.

2. The temperature sensor according to claim 1, wherein the measurement resistor 1 consists of a surface-mounted device sealed by the plastic cover 10 against its surroundings in which at least two conductors, 4.5 pass hermetically to the gas and the liquid to tr-plows of the plastic cover 10 and the plastic extrusion coating 13 that comes from the measuring resistor to the external connection contacts 8,9.

3. The temperature sensor according to claim 2, wherein the external connection contacts 8.9 consist of welding contacts for a surface mounted device assembly.

4. The temperature set according to claim 1, wherein the measurement resistor 1 is welded to a board 3, which at its end that faces outward from the measurement resistor has at least one electrical connection that is connected to a plug built as an external connection contact 8,9 in the form of a wire! .

5. The temperature sensor according to claim 1, wherein the plastic cover 10 consists of a silicone varnish.

6. The temperature sensor according to claim 1, wherein The external plastic extrusion coating 13 consists of a thermoset plastic.

7. The temperature sensor according to claim 1, wherein the outer plastic cover 13 consists of a transistor contour housing which in the area of its connection surface 20 has external connection contacts in the form of terminals (S ', 9').