Temperature sensor

A temperature sensor is described having a measuring resistor, a printed circuit board onto which the measuring resistor is soldered, a cover plate which is fastened onto the printed circuit board, the cover plate having a recess in which the measuring resistor sits.

RELATED APPLICATIONS

This application claims priority to DE 10 2019 113 046.8, filed May 17, 2019, the entire disclosure of which is hereby incorporated herein by reference.

BACKGROUND AND SUMMARY

This disclosure relates to a temperature sensor comprising a measuring resistor, as is known, for example, from DE 100 35 747 A1. Such temperature sensors are required for temperature monitoring of various devices, in particular in motor vehicles, for example, for heating devices.

This disclosure teaches a way of cost-effectively creating a temperature sensor having a measuring resistor which is suitable for monitoring electrical devices in motor vehicles.

A temperature sensor according to this disclosure comprises a measuring resistor, preferably an NTC resistor (Negative Temperature Coefficient), a printed circuit board onto which the measuring resistor is soldered, and a cover plate which is fastened onto the printed circuit board, preferably via positive substance jointing, for example, by gluing. The cover plate has a recess in which the measuring resistor sits. The measuring resistor is protected with little effort in this way.

The recess of the cover plate can be a blind hole or a through-hole. If the recess is a through-hole, the measuring resistor in the recess of the cover plate can be covered by electrically insulating casting compound, for example, epoxy resin. The cover plate can, for example, be a composite material made of epoxy resin and glass fiber material. Suitable cover plates are inexpensively available as FR4 circuit carrier plates.

An advantageous refinement of this disclosure provides that the printed circuit board forms a flat cable connector. The temperature sensor can be particularly easily connected to a device in this way. In the simplest case, the flat cable connector can be formed by an end section of the printed circuit board, which end section is inserted into a suitable slot for connecting the temperature sensor.

A further advantageous refinement of this disclosure provides that the printed circuit board is a plastic film having metallic conductor tracks. The temperature sensor can advantageously be designed as a flexible flat cable. The printed circuit board is then a strip, thus having a length which is a multiple of the width, for example, a length which is more than five times the maximum width of the printed circuit board. For example, flexible plastic films made of polyimide are suitable. The plastic film preferably has a thickness of not more than 1.0 mm, particularly preferably not more than 0.5 mm, for example, 0.1 mm or less.

A stiffening of the end region in which the measuring resistor is arranged can be achieved by the cover plate and, if necessary, additionally by a plastic plate attached to the underside of the printed circuit board. If another end region of the printed circuit board forms a flat cable connector, stiffening can also be achieved there by a (further) plastic plate and/or a second cover plate.

DESCRIPTION

The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.

The temperature sensor illustrated inFIGS.1and2has a measuring resistor1, preferably an NTC measuring resistor, which is soldered onto an end section of a printed circuit board2. A cover plate3is glued to the end section of the printed circuit board2and has a recess in which the measuring resistor1is arranged. The recess can be, for example, a through-hole or a blind hole and can be filled with electrically insulating casting compound.

The printed circuit board2is a flexible plastic film. In the end region of the printed circuit board2in which the measuring resistor1is arranged, the printed circuit board2can additionally be stiffened by a plastic plate4which is glued to the underside of the printed circuit board2facing away from the measuring resistor1.

The second end section of the strip-shaped printed circuit board2can form a flat plug. The second end section of the printed circuit board2can be stiffened by a further plastic plate5for this purpose. In addition, a second cover plate6can be glued to the printed circuit board2in the region of the second end section.

The printed circuit board2then advantageously forms a flat cable between the two stiffened end sections. Such cables are sometimes referred to as FFC (Flexible Flat Cable).

The conductor tracks on the printed circuit board2can be made of copper, for example. In the end section, in which the printed circuit board2forms a flat plug, the conductor tracks can open into wider contact fields11,12, which are made, for example, of gold or have a gold-plated surface.

The cover plates3,6can, for example, be made of plastic or a composite material, such as epoxy resin and glass fiber material. Plates are available, for example, as FR4 circuit carrier plates. In order to facilitate the attachment of the plates3,4,5,6, said plates can be provided with one or more grip holes8.

REFERENCE LIST