KR20080063746A - Acceleration sensor and sensor device - Google Patents

Acceleration sensor and sensor device Download PDF

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Publication number
KR20080063746A
KR20080063746A KR1020087004961A KR20087004961A KR20080063746A KR 20080063746 A KR20080063746 A KR 20080063746A KR 1020087004961 A KR1020087004961 A KR 1020087004961A KR 20087004961 A KR20087004961 A KR 20087004961A KR 20080063746 A KR20080063746 A KR 20080063746A
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KR
South Korea
Prior art keywords
acceleration sensor
substrate
thermal expansion
acceleration
sensor device
Prior art date
Application number
KR1020087004961A
Other languages
Korean (ko)
Inventor
야스히로 다무라
Original Assignee
가부시키가이샤 씨앤드엔
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 가부시키가이샤 씨앤드엔 filed Critical 가부시키가이샤 씨앤드엔
Priority to KR1020087004961A priority Critical patent/KR20080063746A/en
Publication of KR20080063746A publication Critical patent/KR20080063746A/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
    • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
    • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
    • G01P15/09—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up
    • G01P15/0907—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by piezoelectric pick-up of the compression mode type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
    • G01P3/42—Devices characterised by the use of electric or magnetic means
    • G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
    • G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
    • G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
    • G01P3/488—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals delivered by variable reluctance detectors

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pressure Sensors (AREA)

Abstract

Disclosed is an acceleration sensor (10) wherein an acceleration sensor chip having an acceleration sensor element (16) including a plummet portion (28), which swings in accordance with the acceleration applied thereto, and a base portion (18) for supporting the acceleration sensor element (16) is mounted onto a substrate (12). A buffering member (46) is arranged between the base portion (18) and the substrate (12) for absorbing thermal stress generated when the base portion (18) and the substrate (12) are thermally expanded or contracted.

Description

Acceleration sensor and sensor device

The present invention relates to an acceleration sensor device for detecting acceleration and a sensor device including a plurality of sensors.

Background Art Conventionally, acceleration sensors have been used in airbag systems and the like mounted on automobiles. In recent years, acceleration sensors are also mounted in small information terminals such as mobile phones due to the miniaturization and power saving of the acceleration sensors.

As an operation principle of the acceleration sensor, various methods have been proposed, and one of them is a piezoresistive acceleration sensor using a piezo resistance effect. In a piezoresistive acceleration sensor, a silicon substrate is processed by etching to form a structure comprising a weight portion, a beam portion supporting the weight portion, and a frame body supporting the beam portion. When applied, it forms a piezo resistor whose resistance changes. The acceleration sensor element is integrally bonded to the upper surface of the pedestal formed of glass to constitute the acceleration sensor chip. When acceleration is applied to the acceleration sensor chip, the beam portion is bent by the inertial force of the weight, so that the resistance value of the piezo resistor changes, so that an electrical signal according to the acceleration can be extracted.

When the acceleration sensor chip is mounted on a substrate made of a material such as glass epoxy, which has a larger coefficient of thermal expansion than silicon, thermal stress is generated by thermal expansion or thermal contraction due to temperature change in the external environment, and the acceleration sensor chip is deformed. Output characteristics deteriorate. Japanese Patent Laid-Open No. 10-12805 discloses an example in which an acceleration sensor chip is mounted on a ceramic substrate having a thermal expansion coefficient close to silicon.

However, when the coefficient of thermal expansion is limited to a substrate of a material close to silicon, the degree of freedom in selecting a substrate is low, so that a cheaper substrate may not be selected. In particular, recently, a hybrid sensor device incorporating a plurality of sensors such as an acceleration sensor, a magnetic sensor, and a temperature sensor has been proposed. However, the type of substrate is limited only for the acceleration sensor, which hinders the low cost of the sensor device. there was.

This invention is made | formed in view of such a situation, The objective is to provide the acceleration sensor apparatus and sensor apparatus which can suppress deterioration of the output characteristic by thermal expansion or thermal contraction.

In order to solve the said subject, the acceleration sensor apparatus of one aspect of this invention is a board | substrate; An acceleration sensor device comprising an acceleration sensor element including a weight that oscillates according to an applied acceleration, and an acceleration sensor chip having a pedestal portion for supporting the acceleration sensor element, wherein both of the pedestal portion and the substrate have thermal expansion or thermal contraction; A shock absorbing member is installed to absorb thermal stress generated at the time.

According to this aspect, the buffer member provided between the pedestal part and the board | substrate absorbs the thermal stress which arises when thermal expansion or thermal contraction is carried out. Even when there is a difference in the thermal expansion coefficient between the pedestal portion of the acceleration sensor chip and the substrate, the buffer member can suppress deformation of the acceleration sensor chip and suppress deterioration of output characteristics, thereby increasing the degree of freedom in selecting a substrate.

The thermal expansion coefficient of the buffer member may be substantially the same as the thermal expansion coefficient of the pedestal portion. By making the thermal expansion coefficients of the buffer member and the pedestal part substantially the same, thermal stress can be suitably absorbed to prevent deterioration of output characteristics.

The substrate may be a glass epoxy substrate, and the pedestal may be formed using silicon or glass close to the thermal expansion coefficient, and the buffer member may be formed using silicon or glass close to the thermal expansion coefficient. Even when a glass epoxy substrate having a thermal expansion coefficient of 10 times or more of silicon is used, a buffer member made of silicon or glass close to the thermal expansion coefficient absorbs thermal stress, thereby preventing deterioration of output characteristics. Since a glass epoxy substrate is cheaper than a ceramic substrate, the manufacturing cost of an acceleration sensor apparatus can be reduced.

The pedestal portion and the buffer member may be fixed using a silicone adhesive, and the buffer member and the substrate may be fixed using a silicone adhesive. In this case, generation of thermal stress due to thermal expansion or thermal contraction of the adhesive can be suppressed, and deterioration of output characteristics can be suppressed more preferably.

Another aspect of the invention is a sensor device. This sensor apparatus is provided with the above-mentioned acceleration sensor apparatus, the magnetic sensor which detects magnetism, and the pressure sensor which detects a pressure. In this case, the sensor apparatus which integrated the some sensor can be comprised. Since the degree of freedom of selection of the substrate is increased, a more inexpensive substrate can be selected, and the manufacturing cost of the sensor device can be reduced.

Combinations of any of the above components and conversion of the expression of the present invention between methods, systems and the like are also effective as aspects of the present invention.

According to the present invention, it is possible to provide an acceleration sensor device and a sensor device in which deterioration of output characteristics due to thermal expansion or thermal contraction is reduced.

1 is a cross-sectional view of an acceleration sensor device according to an embodiment of the present invention.

2 is a perspective view of an acceleration sensor chip.

(A) is a figure which shows the sensor apparatus which packaged several types of sensors into one package, (b) is sectional drawing along the line B-B 'of the sensor apparatus shown to (a).

<Description of the code>

10 acceleration sensor device

12 boards

14 caps

15 package

16 acceleration sensor element

18 pedestal

20 acceleration sensor chip

26 beams

28 Chubu

30 frames

32 bonding pads

34 wire

38 soldering ball

40 signal processing chip

42 Piezo Resistor

44, 48, 64 adhesive

46 Shock Absorbing Member

50 magnetic sensor chips

60 pressure sensor chip

100 Hybrid Sensor Unit

1 is a cross-sectional view of an acceleration sensor device 10 according to an embodiment of the present invention. The acceleration sensor device 10 is an acceleration sensor device of a ball grid array (BGA) type. The acceleration sensor device 10 is mounted in, for example, a small information terminal such as a mobile phone, and is used for the purpose of detecting the inclination of the small information terminal by detecting the acceleration in the three-axis direction.

In the acceleration sensor device 10, as shown in FIG. 1, an acceleration sensor chip 20 and a signal processing chip 40 are mounted on a package 15 including a substrate 12 and a cap 14.

A circuit wiring (not shown) is formed on the upper surface of the substrate 12 and inside the substrate. The lower surface of the board | substrate 12 is provided with the some solder ball 38 which functions as an external terminal for inputting and outputting an acceleration signal or a power supply voltage. The substrate 12 may be a glass epoxy substrate.

2 is a perspective view of the acceleration sensor chip 20. The acceleration sensor chip 20 shown in FIG. 1 is a cross section along the line AA ′ of FIG. 2. The acceleration sensor chip 20 is provided with the acceleration sensor element 16 which is an element which detects acceleration, and the base part 18 which supports the acceleration sensor element 16. As shown in FIG.

The acceleration sensor element 16 forms a structure composed of the frame 30, the beam portion 26, the weight portion 28 by dry etching, using silicon as a base material, and the piezo resistor element (on the beam portion 26). 42).

The frame 30 serves as a base of the acceleration sensor chip 20 and is formed in a quadrangular shape. The beam section 26 extends from the four inner surfaces of the frame body 30 toward the inward direction of the frame body 30 and intersects near the center of the opening of the frame body 30. The thickness of the frame 30 is about 250 micrometers.

As shown in FIG. 2, the beam part 26 is formed so that the upper surface may become coplanar with the upper surface of the frame 30. As shown in FIG. The beam part 26 may be formed so that the upper surface may be spaced apart from the upper surface of the frame 30. That is, the beam part 26 may be provided and extended in the position between the upper surface and lower surface of the inner surface of the frame body 30. As shown in FIG. The thickness of the beam part 26 is formed in the shape which has thin thickness so that it may have elasticity, and it is preferable to form it in about 5 micrometers.

The weight 28 swings in accordance with the magnitude of the applied acceleration to change the amount of warpage of the beam 26. The weight portion 28 is formed to extend downward from the lower surface of the beam portion 26 at the portion where the four beam portions 26 intersect. The weight portion 28 is a rectangular columnar lump.

The piezoresistive element 42 converts the amount of deflection when the beam portion 26 is deformed into an electric signal. The piezoresistive element 42 is formed on the surface of the beam part 26, and 4 elements per axis | shaft and 12 elements in total are arrange | positioned in the position where the beam part 26 is most stress-concentrated, respectively. The signal proportional to the acceleration constitutes a Wheatstone bridge circuit with four elements on each axis, and detects resistance change due to stress as a voltage change. The detected acceleration signal is output from the bonding pad 32.

The pedestal portion 18 is made of silicon or glass close to the coefficient of thermal expansion with silicon. Here, the thermal expansion coefficient of the silicon is 3 × 1O -6 / ℃ degree, and also the glass and the degree of silicon whose thermal expansion coefficient is close to the thermal expansion coefficient of glass is 2.5 ~ 4.5 × 10 -6 / ℃ . The pedestal part 18 is a rectangular flat plate, and as shown in FIG. 1, a part of the upper surface is dug in order to ensure the space which the weight part 28 swings. The pedestal part 18 is joined by the anodic bonding at the acceleration sensor element 16 and the periphery of the opening of the frame body 30. The thickness of the pedestal part 18 is about 250 micrometers.

In the signal processing chip 40 shown in FIG. 1, a processing circuit for computing an acceleration signal obtained in each axial direction from the Wheatstone bridge circuit of the piezoresistive element 42 is integrated. Although not shown, a memory element chip such as an EEPROM for storing data necessary for arithmetic processing may be provided.

The acceleration sensor chip 20 and the signal processing chip 40 are mounted on the substrate 12 and electrically connected to each other via wires 34 and wires (not shown) provided on the substrate 12. The acceleration sensor chip 20 and the signal processing chip 40 are encapsulated by the cap 14.

As shown in FIG. 1, the signal processing chip 40 is fixed to the substrate 12 directly through the adhesive 64, and the acceleration sensor chip 20 is disposed between the pedestal 18 and the substrate 12. A shock absorbing member 46 for absorbing thermal stress generated when thermal expansion or thermal contraction is provided is provided. The buffer member 46 is a rectangular flat plate. It is preferable that the upper surface of the shock absorbing member 46 is formed at least the same size as the lower surface of the pedestal part 18, and is formed larger than the lower surface of the pedestal part 18. The thickness of the buffer member 46 is about 100 micrometers. The substrate 12 and the buffer member 46 are fixed through the adhesive 44, and the buffer member 46 and the pedestal part 18 are fixed through the adhesive 48.

When the pedestal portion 18 of the acceleration sensor chip 20 is directly fixed to the substrate 12 without installing the shock absorbing member 46, the substrate 12 and the pedestal portion 18 are changed according to the temperature change of the external environment. Thermal expansion or thermal contraction. As the substrate 12, for example, when a glass epoxy substrate is used, since the glass epoxy has a coefficient of thermal expansion of about 10 to 10x10 &lt; -6 &gt; Thermal stress occurs between. When the pedestal portion 18 is deformed due to this thermal stress, the acceleration sensor element 16 and the beam portion 26 bonded to the pedestal portion 18 are bent, so that the resistance value of the piezo resistor 42 is reduced. Since it changes, the output characteristic of the acceleration sensor apparatus 10 will deteriorate.

In the acceleration sensor device 10 according to the present embodiment, the shock absorbing member 46 provided between the pedestal portion 18 and the substrate 12 absorbs thermal stress and suppresses deformation of the pedestal portion 18. As a result, the bending of the beam part 26 can be suppressed and the change of the resistance value of the piezo resistor element 42 can be suppressed, so that the degradation of the output characteristic of the acceleration sensor device 10 can be prevented.

Conventionally, in order to prevent deterioration of the output characteristics due to thermal stress, it is necessary to select a substrate close to the acceleration sensor chip 20 and the thermal expansion coefficient. For example, when the acceleration sensor chip 20 is made of silicon and glass, a ceramic substrate having a thermal expansion coefficient close to silicon was used. According to the acceleration sensor device 10 according to the present embodiment, by providing the shock absorbing member 46, even when there is a difference in the thermal expansion coefficient between the acceleration sensor chip 20 and the substrate 12, the acceleration sensor chip 20 Since deformation can be suppressed, the freedom of selection of the board | substrate 12 becomes high. For example, since a glass epoxy substrate is cheaper than a ceramic substrate, the manufacturing cost of the acceleration sensor apparatus 10 can be reduced.

It is preferable that the thermal expansion coefficient of the shock absorbing member 46 is substantially the same as the thermal expansion coefficient of the pedestal portion 18. For example, when the pedestal portion 18 is formed using silicon or glass close to the thermal expansion coefficient, the buffer member 46 is also preferably formed using silicon or glass close to the thermal expansion coefficient. If there is a difference in coefficient of thermal expansion between the cushioning member 46 and the pedestal portion 18, there is a possibility that the cushioning member 46 deforms the pedestal portion 18 by thermal expansion or thermal contraction. By making the thermal expansion coefficients of the shock absorbing member 46 and the pedestal part 18 substantially the same, thermal stress can be suitably absorbed and the degradation of output characteristics can be prevented. When silicon is used as the buffer member 46, the buffer member 46 can be formed by dicing a mirror wafer of silicon into a predetermined shape.

In addition, the pedestal 18 and the buffer member 46 is fixed using a silicone adhesive, the buffer member 46 and the substrate 12 is preferably fixed using a silicone adhesive. For example, when an epoxy adhesive is used as the adhesives 44 and 48, there is a possibility that the output characteristics of the acceleration sensor device 10 may be deteriorated by the influence of thermal expansion or thermal contraction of the adhesive. By using a silicone adhesive, deterioration of the output characteristic by the influence of an adhesive can be suppressed. In addition, since the signal processing chip 40 does not have a mechanically varying portion, it is not necessary to provide a shock absorbing member, and the type of the adhesive 64 is not limited.

FIG. 3A is a diagram illustrating a hybrid sensor device 100 in which a plurality of types of sensors are packaged in one. FIG. 3B is a cross-sectional view taken along the line B-B 'of the hybrid sensor device 100 shown in FIG. The hybrid sensor device 100 includes an acceleration sensor chip 20, a magnetic sensor chip 50 for detecting a geomagnetism, a pressure sensor chip 60 for detecting pressure, and a signal processing chip for processing signals output from these sensors. 40.

The hybrid sensor device 100 is mounted on a small information terminal, for example, and is corrected by the signal processing chip 40 using the inclination angle measured by the acceleration sensor chip 20 using the azimuth angle measured by the magnetic sensor chip 50. Each sensor can cooperate to perform sensing. In the hybrid sensor device 100, since a plurality of sensors are packaged in one, the small hybrid sensor device 100 can be realized. In FIG.3 (a), (b), illustration of the wire which electrically connects each chip | tip is abbreviate | omitted.

Also in the hybrid sensor device 100, a buffer member 46 is provided between the substrate 12 and the acceleration sensor chip 20 in order to suppress deterioration of output characteristics due to temperature changes in the external environment. On the other hand, since the signal processing chip 40, the magnetic sensor chip 50, and the like do not have mechanical variation, they are fixed to the substrate 12 directly through an adhesive.

Conventionally, in the sensor device including the acceleration sensor device, in order to prevent deterioration of the output characteristics of the acceleration sensor device, a substrate made of a material such as ceramic, which is close to the thermal expansion coefficient of silicon, is used as the substrate of the entire sensor device. , The freedom of selection of the substrate was low.

In the hybrid sensor device 100 shown in FIGS. 3A and 3B, since the buffer member 46 absorbs thermal stress generated between the substrate 12 and the pedestal portion of the acceleration sensor chip 20, the substrate The degree of freedom in selection of (12) is increased, and even a substrate made of a material such as glass epoxy having a larger coefficient of thermal expansion than silicon can be used. As described above, since the glass epoxy substrate is cheaper than the ceramic substrate, the manufacturing cost of the hybrid sensor device 100 can be reduced.

In the above, this invention was demonstrated based on the Example. The embodiments are illustrative, and it is understood by those skilled in the art that various modifications are possible in the combination of their respective components or respective processing processes, and that such modifications are also within the scope of the present invention.

The present invention can be applied to fields related to acceleration sensor devices and sensor devices.

Claims (5)

Board; An acceleration sensor device comprising: an acceleration sensor element including a weight portion oscillating according to an applied acceleration, and an acceleration sensor chip having a pedestal portion for supporting the acceleration sensor element. And a buffer member for absorbing thermal stress generated when both are thermally expanded or thermally contracted between the pedestal and the substrate. The method of claim 1, And the thermal expansion coefficient of the buffer member is substantially the same as the thermal expansion coefficient of the pedestal portion. The method according to claim 1 or 2, The substrate is a glass epoxy substrate, The pedestal portion is formed using silicon or glass close to the coefficient of thermal expansion with silicon, The buffer member is formed using silicon or glass close to the coefficient of thermal expansion with silicon. The method of claim 3, The pedestal portion and the buffer member is fixed using a silicone-based adhesive, The buffer member and the substrate is an acceleration sensor device, characterized in that fixed using a silicone-based adhesive. The acceleration sensor device according to any one of claims 1 to 4, A magnetic sensor for detecting magnetism, And a pressure sensor for detecting pressure.
KR1020087004961A 2008-02-28 2005-08-18 Acceleration sensor and sensor device KR20080063746A (en)

Priority Applications (1)

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KR1020087004961A KR20080063746A (en) 2008-02-28 2005-08-18 Acceleration sensor and sensor device

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Application Number Priority Date Filing Date Title
KR1020087004961A KR20080063746A (en) 2008-02-28 2005-08-18 Acceleration sensor and sensor device

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