DE10330739A1 - A micromechanical module with a sensor, a control-and-evaluation switch and a semiconductor chip useful for computer microprocessors and other electronic equipment involving semiconductor chips - Google Patents

Abstract

A micromechanical module with a sensor (2) and a control-and-evaluation switch (3), arranged on a circuit substrate (4), with a semiconductor chip (5) of circuit substrate embedded in a synthetic plastic composition (6), which has a recess (7) for sensor (2), where recess (7) includes a rubber-elastic synthetic resin composition (8) which covers sensor (3). Independent claims are included for: (1) a sensor housing with a sensor region (13) and a switching region (14), and semiconductor chip (5), embedded in composition (6); (2) a process for production of the module including preparation of circuit substrate (4), application of composition (6) to circuit substrate (3), and introduction of sensor (2) and composition into recess (7).

Description

The invention relates to a microelectromechanical Module with sensor and a housing, and methods of making the same.

Show microelectromechanical modules a microelectromechanical sensor on the mechanical loads converts into electrical signals. To do this, the sensor of electrical Control circuits powered and its electrical signals are evaluated by electronic circuits. In many of the microelectromechanical Modules are also operational amplifiers and / or microprocessors and other electronic components based on semiconductor chips built-in. This installation takes place on substrates which are in one Floor area of a cavity housing are arranged. Here are the semiconductor chips that do not act as sensors protected by appropriate covers while the sensory components are exposed to a mechanical load to be measured.

Decoupling the non-sensory acting electronic semiconductor chips in a common cavity housing however difficult to achieve. There is therefore a latent danger the influence of the control and evaluation circuit by the mechanical load, especially with pressure sensors, the for Vibration detections are used. Especially with vibration loads the wiring of the control and evaluation circuits can be damaged in this way can, that the microelectromechanical module is malfunctioning and provides incorrect data or fails completely.

The object of the invention is a Housing and specify a microelectromechanical module that decouples improved by sensor and control and evaluation circuit, the sensitivity of the sensor increased and a higher one reliability for evaluated Provides data.

This task is solved with the Subject of the independent Expectations. Advantageous developments of the invention result from the dependent claims.

According to the invention, a sensor housing is provided with a sensor area and a circuit area created. The Circuit area of the sensor housing has embedded semiconductor chips in plastic mass with embedded Bond connections. The sensor area is in an open to the outside Cavity arranged, which through a recess in the plastic housing compound is formed. At the bottom of the recess or the cavity protrude flat conductor ends into the recess and surround one central position for a A sensor component.

Such a sensor housing is versatile. So can both optical receiver, as Sensors are arranged in the sensor area without this optical receiving or transmitting components have an influence on the in plastic case embedded semiconductor chips can exercise. In addition to the optical sensors, too acoustic receiver be arranged in the central position of the recess. The sensor housing can be beneficial for Use microelectromechanical sensors, especially with vibration loads, which can be detected by the microelectromechanical sensor, the semiconductor chips with their bond connections in the circuit area this sensor housing reliable protected, since both the semiconductor chips and the bond connections in a plastic housing compound Completely are embedded and anchored and only the sensor area of the sensor housing the vibrations can react.

A microelectromechanical according to the invention Module with such a sensor housing has a microelectromechanical Sensor and a control and evaluation circuit. These are common arranged on a circuit substrate. Here are the semiconductor chips the control and evaluation circuit in a plastic housing compound embedded, which has a recess in which the microelectromechanical Sensor is arranged. The recess can be a rubber elastic Have plastic mass, which is a coupling of the microelectromechanical Sensor to the external pressure conditions allows.

Such a microelectromechanical module has the advantage of an extended Lifespan because vibration exposure does not lead to premature Interrupting the bond connections for the control and evaluation circuit to lead can, especially since this is complete embedded in a plastic housing compound is. Another advantage of the microelectromechanical module is in that it is relatively inexpensive to manufacture on the basis of a lead frame is. For this purpose, a lead frame is used as the substrate Has flat conductor ends that protrude into the sensor area of the sensor housing and at the same time a connection to the control and evaluation circuit, which can be realized by a microprocessor chip. To can Bond wires connect to the flat conductor ends in the recess, and he can about appropriate flat conductors in the circuit area of the sensor housing connected to the sensor.

The flat conductors that protrude into the recess surround the microelectromechanical sensor. Some of the flat conductors protrude through the plastic housing compound and form external contacts. Another part of the flat conductors protrudes into the area of the plastic housing mass in which the semiconductor chips of the control and evaluation circuit are arranged. The control and evaluation circuit supplies the sensor with the necessary energy and on the other hand evaluates the electrical signals triggered by the mechanical load nals of the sensor chip.

To do this, the sensor chip is via bond connections with the flat conductors surrounding it in the recess connected. To create a secure bond connection, they are Flat conductor ends, which in the recess or the cavity protrude with a bondable coating. such bondable coatings can Have gold alloys, silver alloys or aluminum alloys. For the Bonding gold wires Aluminum coatings are suitable, while gold coatings are suitable for bonding with aluminum wires are beneficial.

The plastic housing compound can be an epoxy resin have completely cross-linked before the insertion of the sensor chip and cured is. On the other hand, the sensor chip in the recess of one rubber-elastic plastic mass covered from a silicone rubber to protect it from chemical environmental influences. This plastic mass is transparent to optoelectronic sensors and can be colored for microelectromechanical sensors. This is particularly the case when the microelectromechanical Sensor is a pressure sensor that over the rubber-elastic cover should record pressure fluctuations.

A method of making a microelectromechanical module has the following process steps on. First becomes a circuit substrate with positions for a microelectromechanical Sensor and for Semiconductor chips of a control and evaluation circuit manufactured. This substrate can be a leadframe, which has several chip islands has, one of the chip islands for the microelectromechanical Sensor is reserved while other chip islands are the semiconductor chips of the control and evaluation circuit take up. After manufacturing such a circuit substrate this circuit substrate with the semiconductor chips of the control and evaluation circuit stocked, but not with a sensor chip. Then bond connections between flat conductors of the circuit substrate and the semiconductor chips the control and evaluation circuit.

The evaluation circuit is thus already functional and can be in a plastic case be poured. With this embedding of the bond connections and the semiconductor chips of the control and evaluation circuit in a plastic housing compound, a recess is left in the plastic housing compound, which has flat conductor ends in its base area, which have a central Position surrounded. The central position can also be a Have chip island for receiving the sensor.

The flat conductor ends and the chip island are kept free of plastic housing compound on one side, so in the next Step a microelectromechanical sensor in the central position can be inserted in the recess. Then be Bond connections between the microelectromechanical sensor and manufactured the flat conductor ends. Finally, can protect the microelectromechanical Sensors a rubber-elastic plastic mass in the recess below Covering the sensor chip can be introduced. This procedure has the advantage that it is for the mass production is suitable, and in particular due to the Use of bonded connections and lead frames with conventional ones Process engineering, is compatible.

In summary it can be stated that the non-sensor chips can be molded by default, so that the process of manufacturing such a sensor housing into existing Semiconductor production lines can be integrated. The unenclosed area in the form of a recess or a cavity, one or more Pick up sensor chips.

• – unter Umständen vorhandene Moldwerkzeuge können modifiziert eingesetzt werden,
• – die nicht sensitiven Chips können standardmäßig umhüllt werden,
• – lediglich ein Hohlraum von minimalen Abmessungen ist vorzuhalten und vorzusehen, welcher der Sensorchipgröße entspricht, so dass eine Miniaturisierung von mikroelektromechanischen Modulen möglich ist,
• – die leitende Verbindung von den nicht sensitiven Halbleiterchips zu dem Sensorchip können mittels eines Metallchipträgers, wie einem Flachleiterrahmen, oder durch eine Leiterplatte ausgebildet werden, was eine Massenproduktion ermöglicht,
• – der Dosiervorgang zum Abdecken des Sensorchips kann aufgrund des minimalen Hohlraums der Aussparung präzise gesteuert und mit weniger gummielastischem Material hergestellt werden, was die Kosten des Verfahrens reduziert.
• – ein weiterer Kostenvorteil besteht darin, dass bestehende Prozesse und bestehende Werkzeuge eingesetzt werden können,
• – das Sensorgehäusedesign ist flexibler gestaltbar durch die Miniaturisierung der Aussparung für den Sensorchip,
• – durch eine spannungsfreie Einkapselung der nicht sensitiven Halbleiterchips in eine Kunststoffgehäusemasse wird der Einfluss der zu detektierenden Signale auf Produkteigenschaften von mikroelektromechanischen Bauteilen vermindert,
• – schließlich wird eine höhere Zuverlässigkeit erreicht durch einen formstabileren Aufbau des Sensorgehäuses, durch die Hafteigenschaften der Kunststoffgehäusemasse, in welche die nicht sensitiven Halbleiterchips eingebettet sind und durch den verbesserten Umgebungsschutz, sowohl der nicht sensitiven Halbleiterchips, als auch des Sensorchips.

In summary, the invention has the following advantages:

• - under certain circumstances existing molds can be used modified,
• - the non-sensitive chips can be encased by default,
• Only a cavity of minimal dimensions has to be provided and provided, which corresponds to the sensor chip size, so that miniaturization of microelectromechanical modules is possible,
• The conductive connection from the non-sensitive semiconductor chips to the sensor chip can be formed by means of a metal chip carrier, such as a flat lead frame, or by a printed circuit board, which enables mass production,
• - The dosing process for covering the sensor chip can be precisely controlled due to the minimal cavity of the recess and can be produced with less rubber-elastic material, which reduces the costs of the method.
• - Another cost advantage is that existing processes and tools can be used,
• - The sensor housing design is more flexible due to the miniaturization of the recess for the sensor chip,
• The stress-free encapsulation of the non-sensitive semiconductor chips in a plastic housing compound reduces the influence of the signals to be detected on product properties of microelectromechanical components,
• - Finally, higher reliability is achieved through a more dimensionally stable structure of the sensor housing, through the adhesive properties of the plastic housing compound, in which the non-sensitive semiconductor chips are embedded, and through the improved environmental protection, both of the non-sensitive semiconductor chips and the sensor chip.

The invention is now based on the attached Figures closer explained.

1 shows a schematic cross section through a sensor housing of a first embodiment of the invention,

2 shows a schematic cross section through a microelectromechanical module of a further embodiment of the invention.

1 shows a sensor housing 17 with a sensor area 13 and a circuit area 14 , The circuit area 14 points in a plastic housing compound 6 embedded semiconductor chips 5 with embedded bond connections 10 and flat conductors 9 on. Part of the flat conductor 9 extends to the outside of the housing and forms external contacts 18 while a second part 19 of flat conductors 9 different from the circuit area 14 in the sensor area 13 extends and there flat conductor ends 11 has that in the sensor area 13 protrude and a bondable layer 12 exhibit.

The sensor area 13 is made of a recess 7 the plastic housing mass 6 formed and points on the bottom of the recess flat conductor ends 11 on that a central position 15 surrounded, another part 20 the flat conductor 9 protrude from the sensor housing and external contacts 21 form that with the sensor area 13 correspond. Different sensors can be placed in the central position in such a sensor housing 15 are arranged, the central position 15 in this embodiment of the invention a metallic chip island 22 having.

The sensor housing according to 1 is based on a flat conductor structure that is punched out of a flat conductor frame and as a circuit substrate 4 serves. This flat conductor structure has next to the flat conductors 9 additional chip islands 23 in the circuit area 14 for receiving the semiconductor chips 2 a control and evaluation circuit 3 on. The non-sensitive semiconductor chip 5 In this embodiment of the invention, a microprocessor is provided which supplies the sensor area with energy and also performs control functions of the sensor chip and evaluation functions of the signals of the sensor chip.

2 shows a schematic cross section through a microelectromechanical module. Components with the same functions as in 1 are identified by the same reference numerals and are not discussed separately. The microelectromechanical module 1 is in a sensor housing 17 according to 1 housed, the sensor area 13 with a pressure sensitive microelectromechanical sensor 2 is equipped.

This silicon-based pressure sensor 24 responds to pressure fluctuations caused by a rubber-elastic cover 8th on the pressure-sensitive area of the pressure sensor 24 be transmitted. The bending of a silicon membrane causes a capacitive change between the top of the silicon membrane and a rigid metal-plated glass plate arranged above it, so that pressure fluctuations can be detected via the capacitive change. For this purpose are the electrodes of the pressure sensor 24 via bond connections 10 and corresponding flat conductors 9 , with the control and evaluation semiconductor chip 3 connected.

1

microelectromechanical module

2

microelectromechanical sensor

3

Tax- and evaluation circuit

4

circuit substrate

5

Semiconductor chip

6

Plastic housing composition

7

recess

8th

rubbery Plastic mass and / or cover

9

flat Head

10

bond

11

Flat conductor ends in the recess

12

bondable layer

13

sensor range

14

circuit area

15

central position

17

sensor housing

18

external contacts

19

second Part of flat conductors

20

Another Part of flat conductors

21

external contacts

22

chip island

23

chip island

24

pressure sensor

Claims (9)

Microelectromechanical module with one sensor ( 2 ) and a control and evaluation circuit ( 3 ) that are common on a circuit substrate ( 4 ) are arranged, with semiconductor chips ( 5 ) of the control and evaluation circuit ( 3 ) in a plastic housing compound ( 6 ) are embedded, which have a recess ( 7 ) in which the sensor ( 2 ) is arranged, the recess ( 7 ) a rubber-elastic plastic mass ( 8th ) which the sensor ( 2 ) covered. Microelectromechanical module according to claim 1, characterized in that flat conductor ( 9 ) in the recess ( 7 ) protrude and the sensor ( 2 ), with part of the flat conductors ( 9 ) due to the plastic housing mass ( 6 ) protrude outwards and another part of the flat conductors ( 9 ) in the area of the plastic housing compound ( 6 ) protrude into which the semiconductor chips ( 5 ) of the control and evaluation circuit ( 3 ) are arranged. Microelectromechanical module according to An claim 1 or claim 2, characterized in that the sensor ( 2 ) via bond connections ( 10 ) with the flat conductors surrounding it ( 9 ) is electrically connected. Microelectromechanical module according to one of the preceding claims, characterized in that the in the recess ( 7 protruding ends ( 11 ) the flat conductor ( 9 ) with a bondable layer ( 12 ) are coated. Microelectromechanical module according to one of the preceding claims, characterized in that the plastic housing mass ( 6 ) has an epoxy resin. Microelectromechanical module according to one of the preceding claims, characterized in that the rubber-elastic plastic mass ( 8th ) has a silicone rubber. Microelectromechanical module according to one of the preceding claims, characterized in that the microelectromechanical sensor ( 2 ) a microelectromechanical pressure sensor with rubber-elastic cover ( 8th ) is. Sensor housing with a sensor area ( 13 ) and a circuit area ( 14 ), where the circuit area ( 14 ) in plastic housing compound ( 6 ) embedded semiconductor chips ( 5 ) with embedded bond connections ( 10 ) and flat conductors ( 9 ), and wherein the sensor area ( 13 ) a recess ( 7 ) in the plastic housing compound 86 ) into the flat conductor ends ( 11 ) protrude into a central position ( 15 ) for a sensor component. Method for producing a microelectromechanical module, which has the following method steps: - producing a circuit substrate ( 4 ) with positions for a microelectromechanical sensor ( 2 ) and semiconductor chips ( 5 ) a control and evaluation circuit ( 3 ), - assembling the circuit substrate ( 4 ) with the semiconductor chips ( 5 ) of the control and evaluation circuit ( 3 ), - making bond connections ( 10 ) between flat conductors ( 9 ) of the circuit substrate ( 4 ) and the semiconductor chips ( 5 ) of the control and evaluation circuit ( 3 ), - application of a plastic housing compound ( 6 ) on the circuit substrate ( 4 ) by embedding the semiconductor chips ( 5 ) and the bond connections ( 10 ) of the control and evaluation circuit ( 3 ) and forming a recess at the position of the microelectronic sensor ( 2 ), with flat conductor ends ( 11 ) which the sensor ( 2 ) are kept free from plastic housing, - insert the microelectromechanical sensor ( 2 ) in the recess ( 7 ), - making bond connections ( 10 ) between the microelectromechanical sensor ( 2 ) and the flat conductor ends ( 11 ), - Introducing a rubber-elastic plastic mass ( 8th ) in the recess ( 7 ).