DE102007057903B4 - Sensor module and method for producing the sensor module - Google Patents

Abstract

Sensor module with a sensor chip (3), which is covered with a plastic cover (4), wherein the sensor module is provided with one of a sensor surface (18) of the sensor chip (3) to an outside (7) of the sensor module leading channel (17) and wherein the sensor module from the outside (7) to the sensor chip (3) leading conductor tracks (9, 10, 11), characterized in that the channel (17) on one of the conductor tracks (9, 10, 11) along.

Description

The The invention relates to a sensor module with a sensor chip, which with covered by a plastic cover.

The The invention further relates to a method for producing the sensor module.

Such a sensor module is from the US 2007/0139044 A1 known. In the case of the known sensor module, the sensor chip is applied to a conductor grid and surrounded by a first plastic envelope made of a thermosetting plastic. The inner plastic sheath is further surrounded by an outer plastic sheath which extends to a contact end of the conductor tracks formed by the conductor tracks. At the contact ends of the track, the outer plastic shell is formed as a plug socket. The known sensor module is used in particular for detecting the rotational speed of a turbocharger.

Furthermore, from the US 2004/0118227 A1 a sensor module is known in which a sensor chip is fixed on a conductor grid. The sensor chip and the conductor grid are surrounded by a plastic shell. The conductor tracks of the conductor grid are also connected to contact pins. The transition region between the conductor grid and the contact pins is covered by a further plastic cover, which extends to the contact ends of the contact pins and forms a plug socket there.

When Sensor chips are in particular temperature-sensitive sensor chips, Magnetic field sensitive sensor chips, angular rate sensors or acceleration sensors provided.

One Disadvantage of the known sensor modules is that the plastic cover the Falsify measuring signal can. For example, the additional mass of the plastic cover the Increase the response time of the sensor module. Further, calibrations may be necessary be to correct the influence of the plastic shell.

From the WO 03/068671 A2 a sensor and / or actuator arrangement is known in which at least one sensor or an actuator is provided on or in a chip. On the one hand to protect both the chip and its electrical contacts safely from the environment, but on the other hand to use the sensor or actuator for measurements of parameters of a liquid or gas, the chip is covered with the sensor with a protective cover. At least one channel to a sensor or actuator is provided, which is guided at least partially laterally to the surface of the chip.

The DE 103 04 775 B3 relates to a measuring device and a measuring method for chip-card-shaped biosensors and method for the production thereof. For this purpose, the biosensor has a semiconductor chip with a bioactive structure and contact surfaces. The biosensor is covered by a redistribution substrate. The rewiring substrate projects beyond the semiconductor chip, so that outside contact surfaces of the rewiring substrate are freely accessible.

The DE 10 2004 013 852 A1 discloses a sensor element for determining a physical property of a measurement gas, in particular the concentration of a gas component in a gas mixture, in particular the oxygen concentration in the exhaust gas of internal combustion engines. In order to reduce the waste heat loss of the sensor element caused by convection and radiation to the cold sample gas flow, the outer electrode is arranged in a cavity formed in the solid electrolyte body.

outgoing From this prior art, the invention is based on the object a sensor module improved in terms of measurement properties to accomplish. The invention is also based on the object, a Specify method for producing the sensor module.

These Tasks are performed by the sensor module and the procedure with the Characteristics of the independent claims solved. In dependent claims are indicated advantageous embodiments and developments.

The Sensor module has a Channel coming from a sensor surface of the sensor chip to an outside of the sensor module leads. The term "channel" should be understood to mean a cut-out whose cross-sectional dimensions small in comparison to that of the sensor surface of the sensor chip to the outside measured length the channel is. Through such a channel is the sensor surface of the sensor chip in contact with the environment of the sensor module. In particular, pressure changes in the surrounding medium be detected directly with the sensor module without the influence the plastic cover on the measurement result must be determined by calibrations. The sensor module is provided with tracks and the channel is along a track led to a contact point of the conductor. There is the possibility the channel by a suitable cross-sectional profiling of the conductor track train.

In particular, it is possible to produce the channel by embossing a conductor track when the conductor tracks are formed by a conductor grid. In this case, for example, the channel may be formed by forming a groove in a trace of the Leitergitters are produced. In this context, a conductive grid is to be understood as meaning a self-supporting unit of conductor tracks, wherein the conductor tracks do not necessarily have to be connected to one another after completion of the production. The conductor grid may, for example, be a so-called lead frame. By using such a conductor grid, the strength of the sensor module can be additionally increased. In addition, the production is facilitated, since a stable carrier is available.

The formed in a trace of the conductor grid groove is preferably covered with a foil to prevent that during the Production of plastic cover plastic in the channel area enters and blocks the channel area.

Further The channel may also be formed by a cannula, for example inserted in a groove formed in a conductor track of the conductor grid is. Through such a cannula can be a consistent one Channel from the sensor surface of the sensor chip to the outside be formed of the sensor module.

at a preferred embodiment the sensor module is provided with a further cutout, the from the outside of the sensor module extends to a further sensor surface of the sensor chip. If the sensor chip is a differential pressure sensor, can in this case the differential pressure between the pressure of the medium on the other sensor surface and the voltage applied to the channel sensor surface are determined.

Further Features and advantages of the invention will become apparent from the following Description forth, in the embodiments the invention with reference to the attached Drawing explained become. Show it:

1 an external perspective view of a sensor module;

2 a perspective view of a conductor grid of the sensor module 1 with components applied thereto;

3 a perspective view of the back of the Leitergitters 2 ;

4 a perspective view of a printed circuit board of a modified sensor module with sensor chip applied thereto;

5 an enlarged cross-sectional view of an opposite circuit board;

6 an enlarged cross-sectional view of another circuit board and

7 a perspective view of another modified sensor module.

1 shows an external perspective view of a sensor module 1 in which a ladder grid 2 with a sensor chip 3 is provided. The ladder grid 2 and the sensor chip 3 are from a plastic sleeve 4 Surrounded, up to contact ends 5 of the ladder grid 2 extends. Furthermore, the plastic shell 4 with a cut-out 6 provided from an outside 7 of the sensor module 1 up to a sensor surface 8th of the sensor chip 3 enough.

2 shows a perspective view of the conductor grid 2 that has an inner trace 9 which is intended for occupancy with mass. Next to the track 9 are other tracks 10 and 11 provided via the measuring signals run or the supply voltage to the sensor chip 3 to be led. The sensor chip 3 is on a fork-shaped holding section 12 the conductor track 9 applied and using bonding wires 13 with the tracks 9 to 11 connected. In 2 is also the one through the cutout 6 in the plastic case 4 exposed sensor surface 8th recognizable.

The intended for the occupation of ground trace 9 also has lateral approaches 14 whose ends are made of plastic wrap 4 led out. This can be the outside 7 of the sensor module 1 at least point by point to ground and an electrostatic charge of the surrounding medium with respect to the sensor chip 3 be prevented.

Next to the sensor chip 3 You can also add other components to the ladder grid 2 applied and from the plastic cover 4 be wrapped up. In 2 are for example capacitors 15 and 16 shown that a connection between the inner trace 9 and the outer tracks 10 and 11 produce.

3 shows a perspective view of the back of in 2 shown ladder grid 2 , Based 3 is recognizable that on the back of the inner trace 9 a channel 17 is formed, that of the contact end 5 the conductor track 9 to the fork-shaped holding portion 12 the conductor track 9 leads. Through the channel 17 can a the sensor module 1 surrounding medium to another sensor surface 18 be guided on a support surface 19 of the sensor chip 3 is trained. Accordingly, the sensor chip is 3 preferably a differential pressure sensor, the differential pressure between the sensor surface 8th and the other sensor surface 18 detected.

For the production of the sensor module 1 will be on the back of the ladder grid 2 first a groove 20 formed by the channel 17 should run. The groove 20 can be made, for example, by the groove 20 along the track 9 in the ladder grid 2 is impressed. Subsequently, on the front of the ladder grid 4 the sensor chip 3 applied and using the bonding wires 13 with the ladder grid 4 connected. The other components, such as the capacitors 15 and 16 , are in this step on the ladder grid 2 applied. Then the ladder grid 2 placed in a mold and with the plastic shell 4 envelops. The cut-out 6 is kept free by a suitable core. To the channel 17 on the back of the ladder grid 2 training is done before inserting the ladder grid 2 into the mold into the groove 20 a cannula 21 introduced, extending from the contact end 5 to the holding section 12 extends. Subsequently, the groove 20 and the holding section 12 covered with an adhesive film, leaving the cannula 21 in the groove 20 is secured and the sensor surface 18 is kept free during the molding process.

The plastic cover 4 is preferably formed in a transfer molding process, in which for the plastic shell 4 used material is brought in a pre-cylinder in a flowable state and then pressed into the mold. The inflow of the molding material into the mold is preferably carried out at a pressure below 10 bar. After filling the mold, a repressing operation can be carried out in which the molding compound is placed under a pressure between 50 and 100 bar, to push out remaining air from the mold ,

For the plastic cover 4 are preferably provided plastics based on an epoxy resin, since the parameters such as glass transition temperature T _G , modulus of elasticity and thermal expansion coefficients can be varied by the composition or adjusted via the Vergussparameter.

The sensor module 1 can be modified in different ways. For example, it is possible the conductor grid 2 so far to the sensor surface 18 introduce that no separate cannula for the formation of the channel 17 is required. In this case, the cover may be the back of the ladder grid 2 suffice for a continuous channel 17 that extends from the entrance opening 19 the conductor track 9 up to the sensor surface 18 extends to provide.

Instead of the ladder grid 2 Other circuit carriers can also be used. In 4 is for example a circuit board 22 shown, which also for the sensor module 1 can be used. For example, on the front of the circuit board 22 the sensor chip 3 Applied and using in 4 Not shown bonding wires with also not shown traces on the front of the circuit board 22 connected. Below the sensor chip 3 is a recess 23 provided, extending over the sensor surface 18 of the sensor chip 3 extends. Furthermore, on the back of the circuit board 22 a groove 24 trained, which can be used to one from the contact end 5 the circuit board 22 to the recess 23 train leading channel. This channel can be formed by the groove 24 during the molding process for the plastic shell 4 covered with a foil or by according to 5 a cannula 25 in the groove 24 is inserted.

In addition, it is also possible on the groove 24 to dispense and the channel according to 6 with a cannula applied to the flat back of the circuit board 26 to accomplish.

Further, it is possible on the cutout 6 to dispense and the sensor surface 8th for example, using one on the front of the ladder grid 4 on the approach 14 outward guided cannula 27 to connect with the environment.

Of the Channel can also be formed by two conductor grids be placed on top of each other, with the channel in one of the two Ladder grid or is formed in two Leitgerittern. Finally, can the channel can also be made by providing a needle-shaped slider in the mold will, before or after filling the plastic mass brought into contact with a sensor surface and before the final Harden the plastic mass withdrawn is to prevent sticking of the slider.

In 7 is finally a sensor version 28 represented, in which the in 1 illustrated sensor module 1 can be introduced. In particular, the sensor socket has 28 a recess into which the sensor module 1 can be inserted in the sliding seat. The sensor version 28 preferably has an external hex nut 29 and a threaded portion 30 on, so the sensor mount 28 can be screwed into the wall of a container or a pipe. Because the channel 17 to the end of the contact 5 of the ladder grid 2 is guided, the sensor chip 3 determine the differential pressure between the internal pressure prevailing inside the container or the conduit and the external pressure prevailing outside the container or the conduit.

In addition, it is possible to run a channel so that the internal pressure at different Is measured, for example, to determine the flow rate of a gas. In this respect, there are no restrictions with regard to the course and the cross section of the channel.

If required, the end of the channel can also by a embedded in the plastic sheath membrane protected against contamination become. The membrane may for example be made of polytetrafluoroethylene existing impermeable, but vapor-permeable membrane perforated for connection to the plastic shell in the edge region is. For example, the membrane can be inserted into the mold, fixed there and then in the plastic case be injected.

Finally, instead of a differential pressure sensor and gas concentration sensors can be used, which are connected via a channel 17 connected to the medium.

In conclusion, be noted that features and properties related with a particular embodiment have been described, also with another embodiment can be combined except when for reasons the compatibility is excluded.

Finally will it should be noted that in the claims and in the description the singular includes the plural except when out of context something else results. Especially if the indefinite article is used, both the singular and the plural is meant.

1

sensor module

2

lead frame

3

sensor chip

4

Plastic sheath

5

Contact end

6

cutout

7

outside

8th

sensor surface

9

conductor path

10

conductor path

11

conductor path

12

holding section

13

bonding wire

14

approach

15

capacitor

16

capacitor

17

channel

18

sensor surface

19

bearing surface

20

groove

21

cannula

22

circuit board

23

recess

24

groove

25

cannula

26

cannula

27

cannula

28

sensor version

29

External hex nut

30

threaded portion

Claims (14)

Sensor module with a sensor chip ( 3 ), which comes with a plastic cover ( 4 ), wherein the sensor module is connected to one of a sensor surface ( 18 ) of the sensor chip ( 3 ) to an outside ( 7 ) of the sensor module leading channel ( 17 ) and wherein the sensor module from the outside ( 7 ) to the sensor chip ( 3 ) leading tracks ( 9 . 10 . 11 ), characterized in that the channel ( 17 ) on one of the tracks ( 9 . 10 . 11 ) along. Sensor module according to claim 1, characterized in that the conductor tracks ( 9 . 10 . 11 ) Part of a ladder grid ( 2 ) are. Sensor module according to claim 2, characterized in that the channel ( 7 ) in one in the track ( 9 . 10 . 11 ) formed groove ( 20 ) runs. Sensor module according to claim 3, characterized in that the groove ( 20 ) is covered by a foil. Sensor module according to one of claims 1 to 4, characterized in that the channel ( 17 ) from a cannula ( 21 . 25 - 27 ) is formed. Sensor module according to one of claims 1 to 5, characterized in that the sensor chip ( 3 ) on one of the sensor surfaces ( 18 ) opposite side another sensor surface ( 8th ), which by a in the plastic cover ( 4 ) introduced clearance ( 6 ) is exposed. Sensor module according to one of claims 1 to 6, characterized in that the sensor chip ( 3 ) is a differential pressure sensor. Method for producing a sensor module ( 1 ), in which a sensor chip ( 3 ) with a plastic cover ( 4 ) is covered, wherein in the sensor module ( 1 ) from a sensor surface ( 18 ) of the sensor chip ( 3 ) to an outside ( 7 ) of the sensor module ( 1 ) leading channel and one of the sensor chip ( 3 ) to an outside ( 7 ) of the sensor module ( 1 ) leading track ( 9 . 10 . 11 ), characterized in that the channel ( 17 ) on the conductor track ( 9 . 10 . 11 ) is formed running along. Method according to claim 8, characterized in that the channel ( 17 ) in a conductor carrier ( 2 . 22 ) is formed. Method according to claim 9, characterized in that for the formation of the channel ( 17 ) a groove ( 20 ) in a conductor track ( 9 . 10 . 11 ) of a ladder grid ( 2 ) is introduced. Method according to claim 10, characterized in that the groove ( 20 ) in the conductor grid ( 2 ) is impressed. Method according to claim 8 or 9, characterized in that for the formation of the channel ( 17 ) a groove ( 24 ) in a printed circuit board ( 22 ) is introduced. Method according to one of claims 8 to 12, characterized in that the channel ( 17 ) using one of the sensor surface ( 18 ) to the outside ( 7 ) of the plastic cover ( 4 ) leading cannula ( 21 . 25 - 27 ) is accomplished. Method according to one of claims 10 to 13, characterized in that the groove ( 20 . 24 ) before the start of a molding process for the plastic cover ( 4 ) is covered by a foil.