WO2015135730A1 - Sensor module with a housed sensor in a multilayer circuit board - Google Patents

Abstract

The invention relates to a sensor module in a motor vehicle controller, comprising a housed sensor (3) with connection pins (2, 4), at least one electric component (20) which is connected to the sensor (3) in an electrically conductive manner, and a multilayer circuit board. The multilayer circuit board comprises an upper outer layer (7a, 6) and a lower outer layer (7b, 6), each of which comprises an electrically conductive conductor track layer (7a, 7b) and an insulating circuit board base layer (6), and at least one inner layer (8, 6) between the two outer layers. In the inner layer (6, 8), a circuit board base layer (6) is arranged between the two conductor track layers (8), and the material of the circuit board base layer (6) of the circuit board is a fiberglass base cloth which is impregnated with a resin. The sensor (3) and the at least one electric component (20) are arranged between the upper conductor track layer (7a) and the lower conductor track layer (7b) so as to be completely surrounded by the material of the circuit board base layer (6).

Description

description

Sensor module with a housed sensor in a multilayer printed circuit board

The invention relates to a sensor module with a housed sensor and at least one additional electrical component according to the preamble of claim 1 and to a carrier printed circuit board with such a sensor module according to the preamble of claim 8.

From the prior art, it is well known that in automotive engineering components such as transmission, engine or brake systems are increasingly electronically controlled. For this purpose, there are integrated mechatronic controls, also referred to as on-site electronics, which can be generated by integration of control electronics and associated electronic components such as sensors or valves in the transmission, the engine or the brake system. That is, the control electronics and the associated electronic components are not housed in a separate protected electronics room outside of the transmission, engine or brake system.

Compared to the conventional use of external mounted controllers, this arrangement has enormous advantages in terms of quality, cost, weight and functionality. In particular, this results in a considerable reduction of under prone ^¬ fault prone connectors and lines. The integration of the control unit in the transmission makes high demands on its thermal and mechanical Be ^¬ loadability. The functionality has to be guaranteed over a wide temperature range (about -40 ° C up to 200 ° C) as well as for mechanical vibrations (up to about 40g). Since the control unit is at least partially surrounded by aggressive media such as transmission oil and transmission oil vapor, it must also have a very high degree of tightness compared to these media. In motor vehicles such controllers are used with an electronic control unit and associated components such as sensors for different tasks, the control unit usually a circuit carrier, for. B. includes a printed circuit board and located thereon active and passive elec ^¬ tronic components. For example, when used in a transmission speeds of waves and positions of gear actuators are sensed by means of sensors. On the basis of this information, the electronic control unit controls, among other things, the switching operations in the transmission. The electronic

Control unit is usually arranged on a support plate and enclosed by a housing body. The sensors are electrically connected due to application near the parts to be sensed po sitioned ^¬ and via electrical conductors, in particular punched grid with the electronic control unit. The stamped grid are usually encapsulated in plastic and form with the sensor as an electrical component and a sensor cover a component carrier, also called sensor dome.

WO 2006/108932 AI shows such a control device with a housing, comprising a housing cover for receiving Sen ^¬ sordomes and a housing shell for receiving a control unit and a foil conductor for electrically connecting the punched grid of the sensor dome on the housing cover with the control ^¬ unit ,

A disadvantage of the conventional use of sensor domes is that in the manufacture of a very large number of materials of different mechanical and thermal properties must be used in order to achieve a relatively safe protection against environmental influences, in particular oils. Despite the use of high-quality, cost-intensive materials, failures have repeatedly been recorded, which are largely attributable to exposed copper surfaces on the sensor dome.

Another disadvantage with the use of sensor dome is that the sensors in the sensor dome are structurally susceptible to Vibrations are and that geometric requirements, eg height offset, brackets and the like must be complied with. Furthermore, the production of these domes requires a technically sophisticated process technology and must be integrated into the production lines for the production of the control units, which leads to a higher cost.

There are also applications in which the components to be sensed are located in the immediate vicinity of the control unit and thus can be dispensed with the use of domes as a sensor carrier. The sensor components can be mounted directly on the scarf ^¬ tion carrier or the circuit board of the control unit. The printed circuit boards are usually made of fiber-reinforced

Plastic or ceramic. Due to the miniaturization of the electronic components and the resulting reduction in the available installation space, the trend is towards so-called multi-layer or multilayer printed circuit boards.

Multilayer printed circuit boards made of fiber-reinforced plastic, in particular glass-fiber reinforced plastic, essentially comprise outer and inner layers. An outer layer usually comprises a copper layer or copper foil as a conductive element and a so-called prepreg layer as an insulating element, wherein the prepreg layer consists of a glass fiber base fabric impregnated with resin, in particular epoxy resin.

An inner layer, also called PCB core or core, consists of a prepreg layer between two copper ^¬ layers. The copper layers are formed as conductor track structures. In order to avoid twisting of the multilayer printed circuit board, the layered structure of copper layer and prepreg layer is particularly symmetrical to the innermost

Prepreg layer.

The loading of various components, e.g. SOT23

Hall sensors and SOT89 speed sensors on the surface A circuit carrier, in particular a printed circuit board, by means of different so-called "surface-mounted" technologies is known in the art, and the sensors mentioned are, in particular, housed components.

In this case, the components are mounted on the surface of the printed circuit board in an identically oriented manner by the "surface-mounted" technology, that is to say the connecting legs of the components, also called pins, are aligned on so-called pad surfaces of the printed conductor pattern which are provided with soldering paste, and then in one

Soldered reflow soldering process. The pins on the underside of the component housing are thus just connected to the conductor track structure of the circuit board. This arrangement has in particular when used in Ge ^¬ gear controls the disadvantage that the components can be directly or indirectly come in contact with the gear oil. The aggressive components contained in the gear oil, in particular sulfur components in different concentrations and different states of aggregation, can adversely affect the functionalities of the respective sensor component, which in individual cases can also lead to failure of the respective component. The invention has for its object to provide a sensor module with a housed sensor and at least one additional electrical component for a motor vehicle control unit, which is constructed to save space and provides improved protection ge ^¬ environmental influences, especially aggressive oils.

This object is achieved by a sensor module with the features of claim 1. The sensor module according to the invention comprises a housed sensor with connection pins, at least one electrical component which is electrically conductively connected to the sensor, and a multilayer printed circuit board. The multilayer printed circuit board has an upper Outer layer and a lower outer layer, each having an electrically conductive wiring layer and an insulating circuit board base layer, and the multilayer printed circuit board further comprises at least one inner layer between the two outer layers, wherein the inner layer, a printed circuit board base layer is disposed between two conductor layers. The material of the circuit board base layer is particularly a resin impregnated fiberglass base fabric. The sensor and the at least one electrical component are advantageously arranged between the upper interconnect layer and the lower interconnect layer and completely enclosed with material of the circuit board base layer. The sensor and the electrical component are thereby protected against environmental influences, in particular against aggressive oils.

An electrically conductive connection between interconnect layers is produced by means of plated-through holes. The position and number of plated-through holes can be individually adapted to the corresponding application.

Depending on the requirements, in particular depending on the distance of the sensor to be sensed part, the sensor and the electrical component in an outer layer of an electrically conductive conductor layer and an insulating circuit board base layer, or in an inner layer, an insulating Leiterplattenba ^¬ sisschicht between two electrically conductive conductor layers be arranged.

In particular, external connection pads for electrically connecting the sensor to electrical components outside the sensor module are formed in the lower conductor track layer of the printed circuit board.

Alternatively, the sensor can be electrically connected by means of push-through contacts with electrical components outside the sensor module. The at least one electrical component, which is electrically conductively connected to the sensor, may be a passive component, in particular an interference suppression capacitor. An advantage in the integration of interference suppression in the sensor module are very short and low-impedance conduction paths, which in turn leads to the reduction of the module size and thereby to reduce costs.

Another object of the present invention is to provide a carrier circuit board having a sensor module according to any one of claims 1 to 6.

This object is inventively achieved by a carrier ^¬ printed circuit board with the features of claim 8. In the inventive carrier circuit board, the sensor module is advantageously arranged in a cavity of the carrier printed circuit board and connected to at least one conductor track layer, the carrier board by means of soldering, welding, gluing or through mounting electrically conductive

In the following description, the features and details of the invention in conjunction with the accompanying drawings with reference to embodiments will be explained in more detail. In this case, features and relationships described in individual variants can in principle be applied to all exemplary embodiments. In the drawings show:

1 shows a sensor on a circuit board in SMD technology according to the prior art,

2 shows a known sensor dome according to the prior art,

3 shows a sensor module according to the invention, comprising a housed sensor and an additional electrical component in a multilayer printed circuit board,

4 shows the integration of a sensor module in a Trägerlei ^¬ terplatte, Fig. 5 shows the integration of a sensor module as in FIG. 4, wherein the connection to the carrier board by ^¬ is realized by plug-in assembly, and Fig. 6, a sensor module disposed in a ensordom Art.

Fig. 1 shows a packaged sensor 3 mounted on a printed circuit board 6 by means of known SMD technology.

In this case, the sensor 3 is mounted on the surface of the printed circuit board 6, for example by "surface mounted" technology, ie the connecting legs 2, 4 of the sensor 3, also called connecting pins, are aligned on so-called pad surfaces 1, 5 of the printed conductor structure on the printed circuit board 6 and then soldered in a reflow soldering process. the pins 1, 5 on the bottom of the sensor housing the circuit board 6 are thus connected up to the conductor track structure. This arrangement has in particular when used in Ge ^¬ gear controls the disadvantage that the components particularly in the range Their connections may come into direct or indirect contact with the possibly aggressive gear oil, which in some cases can also lead to failure of the component.

Fig. 2 shows a schematically drawn structure of a known sensor dome. At a sensor 3, in particular this is housed, electrical connection pins 2 are usually arranged in the form of stamped gratings. The lead frame 2 are customary cherweise encapsulated in plastic and form the sensor dome ^¬ housing 10. The sensor 3 is covered at least in close span Sensordomgehäuse 10 with the Sensordomkappe. 11 About the electrical contacts 19, the lead frame 2 are electrically contacted, for example, with an electronic control unit.

A disadvantage of the use of such sensor domes is in particular that it despite the use of higher quality, more expensive Materials repeatedly comes to failures, which are largely due to exposed copper surfaces on the sensor dome. 3 shows a sensor module according to the invention, comprising a housed sensor 3 with connection pins 2, 4, an additional electrical component 20 and a multilayer printed circuit board. The electrical component 20 may be, for example, an interference suppression capacitor. It could also be arranged more than one additional electrical component 20 in the sensor module. The multilayer printed circuit board has an upper outer layer 7a, 6 and a lower outer layer 7b, 6, each having an electrically conductive conductor layer 7a, 7b and an insulating printed circuit base layer 6.

The multilayer printed circuit board furthermore has at least one inner layer 6, 8 between the two outer layers 7a, 6 and 7b, 6, wherein in the inner layer 6, 8 a printed circuit board base layer 6 is arranged between two printed conductor layers 8. In particular, the material of the circuit board base layer 6 is a resin impregnated fiberglass base fabric. The sensor 3 and the component 20 are advantageously arranged between the upper interconnect layer 7a and the lower interconnect layer 7b, here in the outer layer 7a, 6, and completely enclosed with material of the circuit board base layer 6. The sensor 3 and the component 20 are thereby protected against environmental influences, in particular against aggressive oils. The connection pins 2, 4 of the sensor

3 are electrically connected by means of sensor pads 5 with the inner conductor layer 8.

An electrically conductive connection between the conductor track layers 7b, 8 is produced by means of electrically conductive through-contacts 9, so-called vias. The position and number of plated-through holes 9 can in particular be adapted individually to the corresponding application. The electric

Component 20 is here in Fig. 3, as well as in the other figures

4 to 6, for the sake of clarity only schematically drawn. It can in particular in an outer layer 7a, 6 or 7b, 6 or a Inner layer 8, 6 may be arranged. The component 20 is electrically conductively connected to the sensor 3 by means of internal interconnect layers 8 (not shown here). The connection of the component 20 with the conductor layer 8 is realized here via a solder joint 15. Instead of Löterverbindung 15, any other cohesive connection, such as Ver ^¬ stick could apply.

Depending on the design or requirement, in particular depending on the distance of the sensor 3 to the part to be sensed, the sensor 3 may also be arranged in an inner layer 8, 6.

In particular, external connection pads (not shown here) for electrically connecting the sensor 3 to electrical components outside the sensor module are formed in the lower conductor track layer 7b of the printed circuit board.

Fig. 4 shows the integration of a sensor 3 and a to ^¬ sätzlichen member 20 in a multilayer printed circuit board and the subsequent incorporation of this sensor module in a Trägerlei ^¬ terplatte 12. The printed circuit board with the embedded sensor 3 and the additional member 20 is in a cavity 13 Trä ^¬ gerleiterplatte 12 inserted and electrically connected by means of a solder joint 15 with a conductor layer 14 of the carrier circuit board 12. The connection could also be made by means of welding or gluing.

Fig. 5 shows the integration of a sensor module in a carrier circuit board 12 as shown in Fig. 4, but wherein the electrical connection to the carrier circuit board 12 is realized by means of push-through mounting. In this case, a push-through contact 17 on the one hand with a terminal pin 2,4 of the sensor 3 via a corresponding terminal pad 1.5 on an inner conductor layer 8 of the sensor module and on the other hand electrically connected to the Durchsteckkontaktaufnahme 18 of the carrier circuit board 12. About the Durchsteckkontaktaufnahmen 18 then the sensor 3 with the periphery of the carrier circuit board 12 is electrically connected. Advantageously, here the gap between the sensor module and the carrier circuit board 12 by means of a sealant 16 abge ^¬ seals. As a sealant 16, in particular an adhesive or silicone can be used.

Fig. 6 shows schematically a sensor module with a sensor 3 with connection pins 2,4 and an additional component 20, arranged in a kind of sensor dome. The sensor module is at least partially encapsulated in plastic. The plastic forms here the sensor dome housing 10. About the electrical contacts 19 are not shown here trace layers 7a, 7b, 8 of the sensor module electrically contacted, for example with an electronic control unit of a motor vehicle control unit. A significant advantage of the integration of a packaged sensor over the integration of bare-the sensors into a printed circuit board is that an adjustment of the sensor can already be made by the manufacturer. An additional adjustment is therefore not necessary. Furthermore, the sensors are protected against migration of oil by resin or PCB base materials, especially when used in gearbox control systems and thus in their functionality.

Another advantage of this arrangement is that the printed circuit boards can be mass-produced with the integrated sensors and can be used in production like a commercial component in the assembly, in particular of carrier circuit boards. Another advantage of this arrangement is that the

Multilayer PCB can be a large, standardized multilayer PCB surface, and that sensor modules can be separated from the multilayer PCB surface. Reference sign list

1, 5 connection pad

 2, 4 connection pin

 3 sensor

 6 PCB base layer, prepreg layer

7a Upper conductor layer, outer layer

 7b Lower conductor layer, outer layer

8 trace layer, inside

 9 through-connection

 10 sensor housing

 11 sensor dome cap

 12 carrier circuit board

 13 cavity in carrier circuit board

 14 conductor layer, carrier circuit board

15 solder connection

 16 sealant

 17 push-through contact

 18 push-through contact receptacle

 19 Electrical contact

 20 suppression component

Claims

claims Sensor module in a motor vehicle control unit comprising a housed sensor (3) with connection pins (2, 4), at least one electrical component (20), which is electrically conductively connected to the sensor (3), and a multilayer printed circuit board, wherein the multilayer printed circuit board has an upper outer layer (7a, 6) and a lower outer layer (7b, 6) each comprising an electrically conductive wiring layer (7a, 7b) and an insulating circuit board base layer (6), and at least one inner layer (8, 6) between the two Au ^¬ ßenlagen comprises wherein in the inner layer (6, 8) a printed circuit board base layer (6) between two conductor track layers (8) is arranged, characterized in that the material of the circuit board base layer (6) of the circuit board is a resin impregnated glass fiber base fabric, and the sensor (3) and the at least one electrical component (20) between the upper wiring layer (7a) and the lower wiring layer (7b) are completely filled with material of the circuit board base layer ( 6) enclosed, is arranged. 2. Sensor module according to claim 1, characterized in that an electrically conductive connection between conductor track layers (7a, 7b, 8) is produced by means of plated-through holes (9). 3. Sensor module according to one of the preceding claims, characterized in that the sensor (3) and the at least one electrical component (20) in an outer layer ((7a, 6), (7b, 6)) or in an inner layer (8, 6) is arranged. 4. Sensor module according to one of the preceding claims, characterized in that in the lower interconnect layer (7b) external connection pads for electrically connecting the sensor (3) are formed with electrical components (12) outside of the sensor module. 5. Sensor module according to one of the preceding claims, characterized in that the sensor (3) by means of push-through contacts (17) with electrical components (12) outside the sensor module is electrically connected. 6. Sensor module according to one of the preceding claims, characterized in that the electrical component (20) is a passive component, in particular an interference suppression capacitor. 7. Use of a sensor module in a motor vehicle control unit according to one of the preceding claims as a sensor dome, characterized in that the sensor module is arranged in a sensor housing (10) and is electrically connectable by means of contacts (19) to electrical components (12) outside the sensor module. 8. carrier circuit board (12), characterized in that a sensor module according to one of claims 1 to 6 in the cavity (13) of the carrier circuit board (12) is arranged. 9. carrier circuit board (12) according to claim 8, characterized marked ^¬ characterized in that the sensor module with a conductor track layer (14) of the support ^¬ conductor plate (12) by means of soldering, welding, gluing or Through-hole is electrically connected. 10. Arrangement of sensors (3) and associated additional electrical components (20) in a multi-layer printed circuit board, characterized in that the multi-layer printed circuit board is a large, standardized multi-layer printed circuit board surface, and that sensor modules according to one of claims 1 to 6 are detachable from the multi-layer printed circuit board surface.