WO2024146757A1

WO2024146757A1 - Temperature sensor assembly and method for producing a temperature sensor assembly

Info

Publication number: WO2024146757A1
Application number: PCT/EP2023/085645
Authority: WO
Inventors: Wolfram Kienle; Michael Mayer
Original assignee: Robert Bosch Gmbh
Priority date: 2023-01-04
Filing date: 2023-12-13
Publication date: 2024-07-11
Also published as: DE102023200060A1

Abstract

The present invention relates to a temperature sensor assembly (1). The temperature sensor assembly according to the invention comprises a thermal sink (2) for absorbing heat, a retaining clip (3) and a temperature sensor (4). The retaining clip (3) is fastened to the thermal sink (2), and the temperature sensor (4) is fixed by means of the retaining clip (3).

Description

Title and method of producing a

State of the art

The present invention relates to a temperature sensor arrangement and a method for producing a temperature sensor arrangement.

In power electronics, switching modules are used to control motors. High electrical currents in the switching modules result in high losses in the form of heat, which limits the performance. In order to increase the power utilization of the components used, it is necessary to record the temperature of the component. Only with this information is it possible to optimally utilize the performance of the components. This generally applies to thermally stressed components.

Temperature sensors are usually connected to a thermal sink using a thermally conductive medium, such as conductive adhesive. This is often done directly for insulated components. For components that still need to be insulated, an insulating spacer is required. Structures based on direct bonded copper technology are common here, i.e. the component is constructed in an insulating manner using a ceramic spacer.

The temperature sensor is often integrated directly into the circuit carrier that is used for the circuit breakers.

When the temperature sensor is integrated into the circuit breaker, thermal side effects distort the measurement result. This then has to be recalculated, which has a negative impact on the accuracy of the result and means increased effort. The integration of a temperature sensor into a switching module results in an increase in the size of the component and higher costs.

It would be desirable to have a temperature sensor arrangement that enables the measurement of the temperature of a thermal sink in a way that is as easy to manufacture, cost-effective and flexible as possible.

Disclosure of the invention

The temperature sensor arrangement according to the invention according to claim 1 solves this problem. This is achieved by a retaining clip that is attached to a thermal sink. The retaining clip is designed to accommodate a temperature sensor. Furthermore, the retaining clip is inexpensive and can be attached to the thermal sink in a way that is suitable for production. The temperature sensor can be connected to or separated from the retaining clip at any time, which results in flexible manufacturability of the temperature sensor arrangement. Furthermore, the retaining clip enables flexible positioning and good thermal connection of the temperature sensor to the thermal sink.

The temperature sensor is preferably electrically contactable and enables an evaluation of the temperature based on a change in resistance of an electrical conductor in the temperature sensor or on the basis of the thermoelectric effect.

The subclaims show preferred developments of the invention.

The thermal sink preferably has a solderable connection surface, with the retaining clip being soldered onto the solderable connection surface. Solderable layers can be implemented, for example, as a copper cold gas coating. Soldered connections have high mechanical strength and good thermal conductivity at the same time. The process is widespread and inexpensive, especially in electronics production.

Other advantageous joining methods for the retaining clip on the thermal sink include clinching, embossing, riveting, screwing or gluing. The thermal sink is preferably a circuit board or a cooling element or an electrical component. High electrical currents often flow through electrical components from the circuit breaker group in particular, which are a thermal source due to internal resistance and produce waste heat. This can be detrimental to the durability, efficiency and performance of a component and should therefore be monitored using temperature sensor arrangements. Temperature monitoring is best carried out using a thermal sink that is thermally directly connected to the thermal source. These are primarily housings of electrical components, circuit boards or cooling elements.

The retaining clip is preferably a sheet metal component. This can be produced simply and inexpensively from a semi-finished sheet metal product using punching and bending processes. Furthermore, sheet metal retaining clips can have a high thermal conductivity so that the temperature sensor can measure the temperature of the thermal sink as directly as possible. The elastic properties of the sheet metal retaining clip make it possible to produce a retaining clip that securely fixes the temperature sensor. Furthermore, by selecting the retaining clip material, it is possible to make adjustments to the preferred method for the thermal connection to the sink.

As a further advantageous embodiment, retaining clips are possible as a cast component made of metal or plastic.

In a preferred embodiment, the retaining clip fixes the temperature sensor in place with a force fit. A force fit connection is possible, for example, by clamping. Force fit connections can be easily made and released using a joining force. Furthermore, force fit connections usually do not require any additional joining elements. Nevertheless, they represent a possibility for making a secure and permanent connection.

Preferably, the temperature sensor can be fixed in place by the retaining clip. Positive-locking connections are particularly secure but often require additional joining elements. They can be designed to be detachable or non-detachable. An example of a positive-locking connection is a securing clip, which is inserted into the The retaining clip is connected to the retaining clip and now the temperature sensor is positively fixed together with the retaining clip.

It is also preferred that the temperature sensor is fixed by the retaining clip in a form-fitting and force-fitting manner. This results in a particularly secure connection.

Furthermore, the retaining clip can preferably have a contact area which is arranged between the temperature sensor and the thermal sink. This contact area allows a simple connection between the retaining clip and the thermal sink. Furthermore, the contact area preferably has a high thermal conductivity and thus results in a good thermal connection of the temperature sensor to the thermal sink.

In a preferred embodiment, the temperature sensor can be electrically contacted with the thermal sink via electrical contacts. For example, the thermal sink is designed as a circuit board which has electrical contact surfaces to which the temperature sensor is electrically contacted and on which it is fixed via a retaining clip. The temperature sensor can be directly contacted via these contact surfaces in order to record the temperature. It is therefore not necessary to subsequently electrically contact the temperature sensor, for example via a cable. Furthermore, the remaining part of the temperature sensor should be insulated from the thermal sink to avoid a short circuit.

The invention further relates to a method for producing a temperature sensor arrangement. This comprises the steps of joining the retaining clip to the thermal sink, fixing the temperature sensor to the retaining clip and making electrical contact with the temperature sensor. The steps can be carried out in any order. In particular, the temperature sensor can be fixed to the retaining clip both before and after the retaining clip is joined to the thermal sink. The temperature sensor therefore does not have to be fixed directly to the thermal sink, but can be flexibly fixed to the thermal sink using a retaining clip. Preferably, the retaining clip is mounted in the same process step as other electrical components. This reduces the cost and time of production, as no additional process step is necessary. This is not possible with state-of-the-art temperature sensors, as they are usually attached to a thermal sink with a conductive adhesive in an additional cut.

It is also advantageous if the retaining clip is placed on the thermal sink in an automated assembly process. In the assembly process, the retaining clip is preferably mounted together with other electrical components.

Afterwards, both the retaining clip and the other electrical components are preferably soldered.

In a preferred embodiment, the retaining clip and the temperature sensor are pre-assembled onto the thermal sink. This means that the retaining clip can be provided by a supplier pre-installed with the temperature sensor, for example. Then all that is left is to fix the assembly of retaining clip and temperature sensor onto the thermal sink and make electrical contact, which saves time and money.

In a further advantageous embodiment, the temperature sensor is subsequently fixed to the retaining clips connected to the thermal sink. This makes it possible to flexibly attach different temperature sensors designed for different applications to the same retaining clips. Furthermore, the temperature sensor can be attached at any later time and is not tied to a process.

Short description of the drawings

Embodiments of the invention are described in detail below with reference to the accompanying drawing. In the drawing:

Figure 1 is a schematic representation of a thermal sink with solderable connection surfaces according to a first embodiment, Figure 2 is a schematic representation of a

Temperature sensor arrangement according to the first embodiment,

Figure 3 is a schematic detailed view of the

Temperature sensor arrangement according to the first embodiment, and

Figure 4 is a schematic detailed view of a

Temperature sensor arrangement according to a second embodiment.

Embodiments of the invention

Figures 1 to 3 show a first embodiment of a temperature sensor arrangement. Figure 1 shows a thermal sink 2 in the form of a plate-like cooling element 5. Solderable connection surfaces 21 for surface mounting (SMT) of a retaining clip 3 or electrical component 6 are attached to the cooling element 5. The large solderable connection surface 21 is designed to accommodate a circuit breaker. A solder resist is preferably applied between the solderable connection surfaces 21.

A solder paste can be applied to the solderable connection surfaces by solder paste printing. The cooling element 5 is preferably flat and preferably has a high thermal conductivity. Alternatively, it is also possible to apply the retaining clip 3 to a non-flat thermal sink 2.

Figure 2 shows the cooling element 5 from Figure 1 after assembly with the retaining clip 3 and electrical component 6. The circuit breaker can be applied in a later process step. The retaining clip 3 can be applied quickly and inexpensively using the joint assembly process. The retaining clip 3 and the electrical component 6 sit on a solder deposit, which was previously applied to the solderable connection surfaces by means of solder paste printing. The electrical components 6 and the retaining clip 3 can then be soldered by melting the solder deposits in a soldering oven. It is also conceivable that the retaining clip 3 and/or electrical components 6 are designed to be connected to the cooling element 5 by means of through-hole mounting (THT).

Figure 3 shows a detailed view of the temperature sensor arrangement 1 according to the first embodiment. In a previous step, the retaining clip 3 made of sheet metal was soldered to the solderable connection surface 21 and then the temperature sensor 4 was connected to the retaining clip 3.

The temperature sensor 4 has a first electrical contact 41, a second electrical contact 42 and a third electrical contact 43, which protrude parallel to one another and to the surface of the thermal sink 2 from a housing 44 of the temperature sensor 4. The housing 44 is cuboid-shaped and has a bevel on the two upper longitudinal edges. The temperature sensor 4 sits on a contact area 31 of the retaining clip 3.

The housing 44 of the temperature sensor can also be a standardized housing, for example a transistor outline (TO) housing.

The contact area 31 in the first embodiment has two outer webs

32, which are arranged parallel to each other, perpendicular to the electrical contacts 41, 42, 43 and are connected in the middle. A tab branches off from the central connection, which has been folded and has a lateral stop

33 for the temperature sensor 4. The flat outer webs 32 merge into an upwardly curved area 34 on the side opposite the stop 33. The bending diameter of the curved area 34 is slightly larger than the height of the temperature sensor 4. The curved area 34 describes the shape of a semicircle. The curved areas 34 are adjoined by connecting webs 35 which are slightly bent downwards in the direction of the temperature sensor 4. The two connecting webs 35 are connected by a fixing area 36 which is arranged perpendicular to the connecting webs. The fixing area lies flat on the temperature sensor 4 and fixes it. The long ends of the fixing area 36 are characterized by upwardly angled surfaces 37. They make it easier to insert the temperature sensor 4 into the retaining clip 3 from the side. An upwardly bent tab 38 is attached to the long edge of the fixing area that protrudes from the curved area 34. The upwardly bent tab 38 makes it easier to bend the fixing area 36 upwards in order to attach or remove the temperature sensor 4 in the retaining clip 3.

The retaining clip 3 is elastically bent in Figure 3 in order to fix the temperature sensor 4. Due to the elastic deformation, the retaining clip 3 exerts a holding force on the temperature sensor 4 via the fixing area 36 and fixes it in the retaining clip 3 with a force fit. The lateral stop 33 fixes the temperature sensor 4 laterally with a form fit. Without the temperature sensor 4 installed, the curved area 34 is bent slightly further downwards and the fixing area 36 is therefore closer to the contact area 31.

As a second method of the first embodiment, the temperature sensor 4 can be connected to the holding clip 3 before being fixed on the thermal sink 2.

Thus, the temperature sensor arrangement 1 and the steps for producing the temperature sensor arrangement 1 with the features of the first embodiment enable a production-friendly, cost-effective and flexible measurement of the temperature on a thermal sink.

Figure 4 shows a detailed view of a temperature sensor 4 in a retaining clip 3 according to a second embodiment. The retaining clip 3 made of sheet metal is made in two parts in the second embodiment. The lower part 8 has a U-shaped cross section with a flat contact area 31 and two inner side walls 81 bent upwards by 90°. The inner side walls 81 have a punched-out rectangular window 82 in the middle. The inner distance between the parallel inner side walls 81 corresponds to the width of the temperature sensor 4.

The upper part 7 also has a U-shaped cross-section with two outer side walls 71 bent downwards by 90°. The outer side walls are bent outwards at the outer end to enable better joining of the upper and lower parts 7, 8. The inner distance between the outer side walls 71 corresponds to the outer distance of the inner side walls 81. The outer side walls 71 also have an inwardly pressed indentation 72 which is designed to engage in the rectangular window 82 of the inner side walls 81. As a result of the indentation 72 engaging in the rectangular window 82, the upper part 7 sits firmly on the lower part 8 and can only be removed by bending up the outer sides 71. The upper side 73 of the upper part 7 between the two outer side walls 71 has an arched, downwardly bent elastic cross-section. In the joined state, it is in contact with the temperature sensor 4 and exerts a holding force on it, so that the temperature sensor 4 is connected to the holding clip 3 both force-fitting and form-fitting.

Claims

Expectations

1. Temperature sensor arrangement (1) comprising a thermal sink (2) for absorbing heat, a retaining clip (3) and a temperature sensor (4),

• wherein the retaining clip (3) is attached to the thermal sink (2), and

• the temperature sensor (4) is fixed by means of the retaining clip (3).

2. Temperature sensor arrangement (1) according to claim 1, wherein the thermal sink (2) has a solderable connection surface (21) and wherein the retaining clip (3) is soldered onto the solderable connection surface (21) of the thermal sink (2).

3. Temperature sensor arrangement (1) according to one of the preceding claims, wherein the thermal sink (2) is a circuit board or a cooling element (5) or an electrical component (6), in particular a circuit breaker.

4. Temperature sensor arrangement (1) according to one of the preceding claims, wherein the retaining clip (3) is a sheet-metal component.

5. Temperature sensor arrangement (1) according to one of the preceding claims, wherein the retaining clip (3) fixes the temperature sensor (4) in a force-fitting manner.

6. Temperature sensor arrangement (1) according to one of the preceding claims, wherein the retaining clip (3) fixes the temperature sensor (4) in a form-fitting manner.

7. Temperature sensor arrangement (1) according to one of the preceding claims, wherein the retaining clip (3) comprises a contact region (31) which is arranged between the temperature sensor (4) and the thermal sink (2).

8. Temperature sensor arrangement (1) according to one of the preceding claims, wherein the temperature sensor (4) can be electrically contacted via the thermal sink (2).

9. Method for producing a temperature sensor arrangement (1) on a thermal sink (2), comprising the steps of

• Attaching a retaining clip (3) to the thermal sink (2),

• Fixing a temperature sensor (4) to the retaining clip (3), and • electrically contacting the temperature sensor (4).

10. The method according to claim 9, wherein the retaining clip (3) is mounted in the same process step with other electrical components.

11. The method according to claim 9 or 10, wherein the retaining clip (3) is fixed to the thermal sink (2) in an automated assembly process.

12. The method according to claim 9 to 11, wherein the retaining clip (3) and the temperature sensor (4) are pre-assembled onto the thermal sink (2).

13. The method according to claim 9 to 11, wherein the temperature sensor (4) is fixed to the holding clip (3) after the holding clip (3) has been attached to the thermal sink (2).