U.S. patent application number 11/417109 was filed with the patent office on 2006-11-16 for physical quantity sensor device.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Tameharu Ohta.
Application Number | 20060255441 11/417109 |
Document ID | / |
Family ID | 37295610 |
Filed Date | 2006-11-16 |
United States Patent
Application |
20060255441 |
Kind Code |
A1 |
Ohta; Tameharu |
November 16, 2006 |
Physical quantity sensor device
Abstract
A circuit board is mounted on a package via an adhesive agent as
an elastic member. A sensor element is stacked in fixed relation
onto the circuit board. The sensor element, the circuit board, and
the package are wired with bonding wires. A magnetic member made of
a ferromagnetic material is disposed between the adhesive agent and
the circuit board.
Inventors: |
Ohta; Tameharu;
(Takahama-city, JP) |
Correspondence
Address: |
POSZ LAW GROUP, PLC
12040 SOUTH LAKES DRIVE
SUITE 101
RESTON
VA
20191
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
37295610 |
Appl. No.: |
11/417109 |
Filed: |
May 4, 2006 |
Current U.S.
Class: |
257/680 |
Current CPC
Class: |
H01L 2224/73265
20130101; H01L 2224/92247 20130101; H01L 2924/13091 20130101; H01L
2224/32145 20130101; H01L 2224/32145 20130101; H01L 2924/00
20130101; H01L 2224/32225 20130101; H01L 2224/73265 20130101; H01L
2224/48227 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2224/48227 20130101; H01L 2924/00 20130101; H01L 2224/48227
20130101; Y10T 29/4913 20150115; G01C 19/56 20130101; H01L
2224/73265 20130101; H01L 2924/10253 20130101; H01L 2224/48227
20130101; H01L 2224/32145 20130101; H01L 2924/00 20130101; H01L
2924/00 20130101; H01L 2224/73265 20130101; H01L 2924/00 20130101;
H01L 2224/32225 20130101; H01L 2224/92247 20130101; H01L 2924/1305
20130101; H01L 2224/92247 20130101; H01L 2924/13091 20130101; H01L
2224/32225 20130101; H01L 2924/1305 20130101; H01L 2224/73265
20130101; G01P 1/023 20130101; H01L 2224/48227 20130101; H01L 24/32
20130101; H01L 2924/10253 20130101 |
Class at
Publication: |
257/680 |
International
Class: |
H01L 23/02 20060101
H01L023/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 13, 2005 |
JP |
2005-141066 |
Claims
1. A physical quantity sensor device comprising: a sensor element
for sensing a physical quantity; a package to which the sensor
element is mounted; an elastic member having elasticity, disposed
between the sensor element and the package for holing the sensor
element to the package, the elastic member facing (i) a first space
including the sensor element and (ii) a second space opposing the
first space; and a magnetic member, which is made of a
ferromagnetic material and included in the first space.
2. The physical quantity sensor device of claim 1, wherein the
magnetic member is disposed between the elastic member and the
sensor element.
3. The physical quantity sensor device of claim 2, further
comprising: a circuit board mounted to the package via the elastic
member, wherein the sensor element is stacked in fixed relation to
the circuit board, and the magnetic member is disposed between the
elastic member and the circuit board.
4. The physical quantity sensor device of claim 2, further
comprising: a circuit board fixed to the package, wherein the
sensor element is stacked to the circuit board via the elastic
member, and the magnetic member is disposed between the elastic
member and the sensor element.
5. The physical quantity sensor device of claim 1, further
comprising: a second magnetic member, which is made of a
ferromagnetic material and included in the second space with
respect to the elastic member, wherein the magnetic member included
in the first space with respect to the elastic member is referred
to as a first magnetic member, the first magnetic member and the
second magnetic member oppose each other, and the elastic member is
disposed between the first magnetic member and the second magnetic
member.
6. The physical quantity sensor device of claim 5, further
comprising: a protruding portion provided to at least one of
opposing portions of the first magnetic member and the second
magnetic member for allowing the elastic member to retain a
thickness between the first magnetic member and second magnetic
member.
7. The physical quantity sensor device of claim 5, further
comprising: a protruding portion provided to an end portion of the
first magnetic member to oppose the package, for allowing the
elastic member to retain a thickness between the first magnetic
member and second magnetic member.
8. The physical quantity sensor device of claim 5, further
comprising: a protruding portion provided to the first magnetic
member to oppose the package without being intervened by the second
magnetic member, for allowing the elastic member to retain a
thickness between the first magnetic member and second magnetic
member.
9. The physical quantity sensor device of claim 1, wherein the
elastic member includes an adhesive agent made of a resin.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2005-141066 filed on May
13, 2005.
FIELD OF THE INVENTION
[0002] The present invention relates to a physical quantity sensor
device including a sensor element for sensing a physical quantity;
the sensor element is mounted on a package and held thereby via an
elastic member having elasticity.
BACKGROUND OF THE INVENTION
[0003] A physical quantity sensor device of this type typically
includes a sensor element for sensing a physical quantity such as
an angular velocity or acceleration; the sensor element is mounted
on a package. This type of physical quantity sensor device has an
application as an angular velocity sensor device or acceleration
sensor device.
[0004] In such a physical quantity sensor device, a problem occurs
in sensor characteristics when an impact from the outside, i.e., an
external acceleration is applied thereto.
[0005] For example, an angular velocity sensor device senses an
angular velocity based on a Coriolis force generated in a sensing
direction. However, an acceleration in the sensing direction may be
transmitted to a sensor element from the outside via a package even
when an angular velocity is not actually applied thereto. Here, an
output is produced as though an angular velocity occurred.
[0006] With respect to such a physical quantity sensor device, a
structure has been conventionally proposed in which a sensor
element is held on a package via an elastic member having
elasticity such as an adhesive agent or rubber. Here, the elastic
member functions as an anti-vibration member to absorb unnecessary
vibration resulting from an external acceleration (see, e.g.,
PATENT DOCUMENTs 1 to 7).
[0007] In such a structure, the external acceleration is attenuated
by the elastic function of the elastic member in a path in which
the external acceleration is transmitted to the sensor element via
the package. The attenuated external acceleration is thus
transmitted to the sensor element. Accordingly, this structure may
reduce the unnecessary vibration to the sensor element.
[0008] In this structure of the physical quantity sensor device,
however, it may be difficult to properly perform bonding relative
to a component (e.g., sensor element) mounted on the elastic
member, or to properly mount the component on the elastic member.
This may cause a problem that sufficient assembly cannot be
obtained.
[0009] FIG. 8 is a view showing a schematic cross-sectional
structure of a conventional physical quantity sensor device when,
e.g., a low-elasticity adhesive film is used as an elastic
member.
[0010] In FIG. 8, a circuit board 1300 is mounted on a package 1100
and fixed thereto. A sensor element 1200 is stacked on the circuit
board 1300 via an adhesive film 1400 as the elastic member. The
sensor element 1200 and the circuit board 1300 are wired with
bonding wires 1500 to be electrically connected.
[0011] In the conventional physical quantity sensor device, to form
a soft adhesion structure for serving as an anti-vibration
structure, the low-elasticity adhesive film 1400 is used as the
adhesion portion thereof. In the structure, the low-elasticity
adhesive film 1400 is used to fix the sensor element 1200 located
thereon for an anti-vibration purpose. As a result, the upper
portion of the adhesive film 1400 is low in rigidity.
[0012] Wire bonding may be performed relative to the mounted
component, i.e., sensor element 1200 on the adhesive film 1400, or
another component may be mounted in addition to the sensor element
1200. In this case, the holding of the sensor element 1200 becomes
unstable so that assembly such as bonding or mounting becomes
difficult.
[0013] In contrast, to design the structure to be stable during the
assembly, the adhesive film 1400 as the elastic member should be
hardened. This causes a problem that the elastic function of the
adhesive film 1400 is not performed, the amount of attenuation is
reduced, and the external acceleration is more likely to be
transmitted to the sensor element 1200.
[0014] Patent Document 1
[0015] JP-H11-218424 A
[0016] Patent Document 2
[0017] JP-H11-264731 A
[0018] Patent Document 3
[0019] JP-2002-195834 A
[0020] Patent Document 4
[0021] JP-2002-250627 A
[0022] Patent Document 5
[0023] JP-2003-21515 A
[0024] Patent Document 6
[0025] JP-2003-28647 A
[0026] Patent Document 7
[0027] JP-2003-21647 A
SUMMARY OF THE INVENTION
[0028] An object of the present invention is to provide a physical
quantity sensor device capable of addressing the foregoing problem.
This physical quantity sensor device includes a sensor element for
sensing a physical quantity: the sensor element is mounted on a
package and held thereby via an elastic member having elasticity.
This physical quantity sensor device is to properly balance the
trade-off between the elastic function and efficient assembly.
[0029] As an aspect of the present invention, a physical quantity
sensor device is provided as follows. A sensor element is included
for sensing a physical quantity. A package to which the sensor
element is mounted is included. An elastic member having elasticity
is included to be disposed between the sensor element and the
package for holing the sensor element to the package. The elastic
member faces (i) a first space including the sensor element and
(ii) a second space opposing to the first space. A magnetic member
made of a ferromagnetic material is included in the first
space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a schematic cross-sectional view of an angular
velocity sensor device as a physical quantity sensor device
according to a first example embodiment of the present
invention;
[0031] FIG. 2 is a schematic plan view of a sensor element in the
angular velocity sensor device shown in FIG. 1.
[0032] FIGS. 3A to 3F are process step diagrams each illustrating a
method for fabricating the angular velocity sensor device shown in
FIG. 1;
[0033] FIGS. 4A to 4C are process step diagrams each illustrating
the fabrication method, which are subsequent to FIGS. 3A to 3F;
[0034] FIG. 5 is a schematic cross-sectional view of an angular
velocity sensor device as a physical quantity sensor device
according to a second example embodiment of the present
invention;
[0035] FIG. 6 is a schematic cross-sectional view of an angular
velocity sensor device as a physical quantity sensor device
according to a third example embodiment of the present
invention;
[0036] FIG. 7 is a schematic cross-sectional view of an angular
velocity sensor device as a physical quantity sensor device
according to a fourth example embodiment of the present invention;
and
[0037] FIG. 8 is a schematic cross-sectional view of a physical
quantity sensor device when a low-elasticity adhesive film is used
as an elastic member, in a prior art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Example Embodiment 1
[0038] FIG. 1 is a view showing a schematic cross-sectional
structure of an angular velocity sensor device S1 as a physical
quantity sensor device according to a first example embodiment of
the present invention.
[0039] Structure, Etc.
[0040] As shown in FIG. 1, the angular velocity sensor device S1
broadly includes the following: a package 100; a circuit board 300
held on the package 100 via an adhesive agent 400 as an elastic
member; a sensor element 200 stacked on the circuit board 300 and
adhered thereto via an adhesive film 600, for sensing an angular
velocity; and bonding wires 500 for coupling the foregoing
components to each other.
[0041] The package 100 contains the sensor element 200 and the
circuit board 300, serves as a base portion for defining a main
body of the angular velocity sensor device S1, and allows the
angular velocity sensor device S1 to contact a proper position of a
subject to measure.
[0042] In an example shown in FIG. 1, the package 100 is a
multilayer substrate including multiple stacked ceramic layers 110
made of, e.g., alumina or the like. Wires (not shown) are formed on
a surface of each of the layers 110 and in through holes formed in
the individual layers 110. The angular velocity sensor device S1
can be electrically coupled to an outside via the wires.
[0043] The package 100 also has a depressed portion 120 in the
bottom portion thereof, to contain the circuit board 300. The
circuit board 300 contained in the depressed portion 120 is mounted
on the bottom portion of the package 100 and fixed thereto via the
adhesive agent 400 as the elastic member.
[0044] The adhesive agent 400 is an elastic member having
elasticity and made of, e.g., a resin such as a silicone gel. The
adhesive agent 400 functions herein as an anti-vibration member to
attenuate an external acceleration applied from the package 100 to
the sensor element 200 as an angular velocity sensing element.
[0045] A lid 140 made of a metal, resin, ceramic, or the like is
attached to an opening of the package 100. The lid 140 seals an
inside of the package 100. The lid 140 is made of a metal herein
and bonded to the package 100 by welding such as seam welding or
brazing.
[0046] The sensor element 200 is stacked on an upper surface of the
circuit board 300 via the adhesive member 600. The adhesive member
600 is harder than the adhesive agent 400 as the elastic member and
has rigidity. As the adhesive member 600, an adhesive film made of,
e.g., a silicone-based resin or the like can be adopted.
[0047] The sensor element 200 is an angular velocity sensing
element for sensing an angular velocity. The sensor element 200 can
be formed as a semiconductor chip that forms a beam structure
having a commonly known comb-tooth structure relative to a silicon
substrate or the like. The sensor element 200 senses a change in
electrostatic capacitance (electric signal) between a movable
electrode and a fixed electrode; the electrostatic capacitance is
responsive to an applied angular velocity.
[0048] Referring primarily to FIG. 2, a description will be given
to a detailed structure of the sensor element 200. FIG. 2 is a view
showing a schematic plan structure of the sensor element 200 in the
angular velocity sensor device S1 shown in FIG. 1.
[0049] The sensor element 200 has a substrate 10 such as a
semiconductor substrate and is formed by performing a well-known
micromachining process with respect to the substrate 10. The
substrate 10 can adopt, e.g., a rectangular SOI
(silicon-on-insulator) substrate. The SOI substrate is formed by
laminating a second silicon layer (second semiconductor layer) on a
first silicon layer (first semiconductor layer) via an oxide film
(insulating layer).
[0050] Beam structures 20 to 60 are defined by trenches, as shown
in FIG. 2. The beam structures 20 to 60 are formed by performing
trench etching, release etching, and the like with respect to a
surface layer of the substrate 10, e.g., the second silicon layer
of the SOI substrate. The beam structures 20 to 60 include a
vibrator 20, beam portions 23 and 40, and electrodes 50 and 60,
which will be described later.
[0051] The vibrator 20 is formed at a center portion of the
substrate 10 and capable of vibrating within a plane horizontal to
the substrate 10, i.e., in the plane in FIG. 2. In this example
embodiment, the vibrator 20 includes a first vibrating portion 21
having a generally rectangular configuration positioned at the
center portion; a second vibrating portion 22 configured as a
rectangular frame positioned around the outer periphery of the
first vibrating portion 21; and a driving beam portion 23 coupling
the first and second vibrating portions 21 and 22 to each
other.
[0052] The vibrator 20 is coupled to an anchor portion 30 provided
on a peripheral portion of the substrate 10 via the sensing beam
portion 40. The anchor portion 30 is fixed to and supported by the
portion of the substrate 10 which is located below the surface
layer formed with the beam structure 20, i.e., the supporting
substrate portion of the substrate 10. The vibrator 20 is floating
from the supporting substrate portion.
[0053] As shown in FIG. 2, the driving beam portion 23 is
configured to extend in, e.g., a y-direction such that it is
elastically deformable substantially only in an x-direction. On the
other hand, the sensing beam portion 40 is configured to extend in,
e.g., the x-direction such that it is elastically deformable
substantially only in the y-direction.
[0054] Of the vibrator 20, the first vibrating portion 21 is
allowed to vibrate in the x-direction (driving vibration direction)
in a plane horizontal to the substrate 10 by the driving beam
portion 23. On the other hand, the whole vibrator 20 is allowed to
vibrate in the y-direction (sensing vibration direction) in a plane
horizontal to the substrate 10 by the sensing beam portion 40.
[0055] Between the first and second vibrating portions 21 and 22,
driving electrodes 50 are provided for causing the driving
vibration of the first vibrating portion 21 in the x-direction. The
driving electrodes 50 are fixed to the supporting substrate portion
mentioned above, similarly to the anchor portion 30. The driving
electrodes 50 are disposed to oppose a comb-tooth portion
(comb-tooth portion for driving) 21a projecting from the first
vibrating portion 21 such that the comb teeth thereof and those of
the comb-tooth portion 21a interdigitate.
[0056] On the other hand, sensing electrodes 60 are provided in an
outer periphery of the second vibrating portion 22. The sensing
electrodes 60 sense an angular velocity around a z-axis
perpendicular to the substrate 10 based on the vibration of the
vibrator 20 and are fixed to the supporting substrate portion,
similarly to the anchor portion 30. The sensing electrodes 60 are
disposed to oppose a comb-tooth portion (comb-tooth portion for
sensing) 22a projecting from the second vibrating portion 22 such
that the comb teeth thereof and those of the comb-tooth portion 22a
interdigitate.
[0057] Additionally, in the present sensor element 200, pads made
of aluminum or the like are provided at appropriate positions on
the substrate 10 to apply voltages to the vibrator 20, driving
electrodes 50, sensing electrodes 60, and the like mentioned above
or to retrieve signals therefrom.
[0058] These pads are provided on, e.g., the peripheral portion of
the substrate 10. To these pads, the above-mentioned bonding wires
500 made of Au (gold), aluminum, or the like are connected, as
shown in FIG. 1. The sensor element 200 according to this example
embodiment has a structure as described above.
[0059] The circuit board 300 used herein is an IC chip or the like
in which, e.g., a MOS transistor, a bipolar transistor, or the like
has been formed by using a well-known semiconductor process on a
silicon substrate or the like. The circuit board 300 can be also a
signal processing chip having functions of sending a voltage to the
sensor element 200, processing an electric signal from the sensor
element 200, outputting the processed electric signal to the
outside, and the like.
[0060] As shown in FIG. 1, the sensor element 200 and the circuit
board 300 are electrically coupled via the above-mentioned bonding
wires 500 made of gold, aluminum, or the like, while the circuit
board 300 and the package 100 are also electrically coupled via the
bonding wires 500.
[0061] Thus, the individual components of the sensor element 200,
the circuit board 300, and the package 100 are electrically
connected via the bonding wires 500. It is to be noted that the
sensor element 200 and the circuit board 300 need not be connected
directly via the bonding wires 500, as shown in FIG. 1.
[0062] For example, the sensor element 200 can be coupled to the
package 100 via the bonding wires 500, while the package 100 is
coupled to the circuit board 300 via the bonding wires 500. In this
case, the sensor element 200 and the circuit board 300 can be
similarly coupled to each other via the bonding wires 500, though
with intervention of the package 100.
[0063] In this manner, an electric signal (capacitance change) from
the sensor element 200 is sent to the circuit board 300, converted
to a voltage signal by a CN conversion circuit or the like provided
on the circuit board 300, and outputted as an angular velocity
signal.
[0064] Thus, the angular velocity sensor device S1 according to
this example embodiment is constructed by successively stacking the
circuit board 300 and the sensor element 200 on the package 100 via
the adhesive agent 400 as the elastic member.
[0065] Further, as a structure peculiar to this example embodiment,
a magnetic member 700 made of a ferromagnetic material is provided
at a given portion. Here, to define the given portion, explanation
will be added. As explained above, the adhesive agent 400 is
disposed between the sensor element 200 and the bottom portion of
the package 100. The adhesive agent 400 has (i) a first side facing
a first space in which the sensor element 200 is included and (ii)
a second side facing a second space that opposes the first space
(in the example in FIG. 1, the second space includes the bottom
portion of the package 100). In other words, the elastic member
faces (i) the first space (also called sensor-element-side space)
including the sensor element and (ii) the second space (also called
package-side space) not including the sensor element 200 (in the
example in FIG. 1, the second space includes the bottom portion of
the package 100). The given portion is defined to be included in
this first space or the sensor-element-side space with respect to
the adhesive agent 400. The magnetic member 700 is thus disposed at
the given portion included in the sensor-element-side space which
the adhesive agent 400 faces via the first side. For instance, in
this example embodiment, the magnetic member 700 is disposed or
interposed between the adhesive agent 400 and the sensor element
200.
[0066] For instance, in this example embodiment, the circuit board
300 is mounted on the package 100 via the adhesive agent 400 as the
elastic member and the sensor element 200 is stacked in fixed
relation onto the circuit board 300, while the magnetic member 700
is interposed between the adhesive agent 400 and the circuit board
300.
[0067] The magnetic member 700 is configured as a plate in this
example embodiment and bonded to the circuit board 300 via a hard
adhesive agent not shown, e.g., an adhesive agent made of a
silicone-based resin or the like. The magnetic member 700A includes
magnetic material with ferromagnetism such as iron, nickel, cobalt,
or an alloy thereof.
[0068] For instance, 42 alloy, Kovar.TM., or the like having a
linear expansion coefficient close to that of the Si chip composing
the circuit board 300 can be used for the magnetic member 700.
However, any material having ferromagnetism at the working
temperature thereof may be appropriately used, provided that it
meets the object of allowing fixation using a magnetic force and
there is no requirement concerning other characteristics.
[0069] In the angular velocity sensor device S1 according to this
example embodiment, it is also possible to preliminarily magnetize
a material such as ferrite, which is a ferromagnetic material, and
use the resulting magnet as the magnetic member 700.
[0070] Fabrication Method, Operation, Etc.
[0071] A method for fabricating the angular velocity sensor device
S1 thus constructed according to this example embodiment will be
described with reference to FIGS. 3A to 3F and FIGS. 4A to 4C.
These figures are process step diagrams for illustrating the
fabrication method according to this example embodiment and are
schematic cross-sectional views obtained by viewing work in the
individual fabrication process steps from the same viewpoint as in
FIG. 1.
[0072] First, as shown in FIG. 3A, the magnetic member 700 is
adhered to the surface of the circuit board 300 to be mounted on
the package 100.
[0073] In this example embodiment, a method has been adopted which
preliminarily processes the magnetic member 700 into the size of
the circuit board 300, i.e., into the chip size and then bonds the
magnetic member 700 to the circuit board 300. However, it is also
possible to bond the wafer-size magnetic member 700 to a wafer of
the circuit boards 300 at a stage before it is cut into individual
chips and then form the circuit boards 300 as the chips with the
magnetic members 700 through simultaneous dicing.
[0074] Next, as shown in FIG. 3B, the adhesive member 600 for
fixing the sensor element 200 is placed on the circuit board 300.
Then, as shown in FIG. 3C, the sensor element 200 is aligned on the
circuit board 300. Then, as shown in FIG. 3D, the sensor element
200 is mounted on the circuit board 300 via the adhesive member 600
and adhesively fixed thereto.
[0075] The sensor element 200 may be also formed as a chip with the
adhesive member 600 by bonding the adhesive member 600 composed of
an adhesive film to a wafer of the sensor elements 200 at a stage
before it is cut into individual chips and then perform
simultaneous dicing. The resulting sensor element 200 may be also
stacked on the circuit board 300 and adhered thereto.
[0076] These process steps result in completing a sensor module in
which the sensor element 200 is stacked in fixed relation onto the
circuit board 300 with the magnetic member 700. Subsequently, the
sensor module is mounted on the package 100.
[0077] First, as shown in FIG. 3E, the adhesive agent 400 as the
elastic member described above is applied onto the bottom portion
of the depressed portion 120 of the package 100. Then, as shown in
FIG. 3F, the sensor module is mounted on the adhesive agent 400
with the magnetic member 700 opposing the bottom portion of the
package 100.
[0078] Then, by curing the adhesive agent 400, the magnetic member
700 of the sensor module is bonded to the package 100. In a
currently reached state, the sensor module, i.e., the circuit board
300 and the sensor element 200 are held by the soft adhesive agent
400 as the elastic member and wire bonding is difficult to perform
in this state.
[0079] When wire bonding is performed, a magnet 800 is provided
herein below the package 100, as shown in FIG. 4A. The magnet 800
can be incorporated into a bonding apparatus or a fixing jig 810
for the package 100 to act as a magnet chuck.
[0080] By the magnet 800, a magnetic force is generated to press
the magnetic member 700 against the package 100 via the adhesive
agent 400. As a result, the movement of the magnetic member 700 is
suppressed and the movement of the sensor module during bonding can
be suppressed. In short, the magnet 800 is constructed as a
magnetic member fixing means for solidly fixing the magnetic member
700 by using a magnetic force.
[0081] As shown in FIGS. 4A to 4B, wire bonding is performed in the
state in which the sensor module described above is solidly fixed
to the package 100 by thus using the magnetic force of each of the
magnet 800 below the package 100 and the magnetic member 700. As a
result, the package 100 and the circuit board 300 are wired with
the bonding wires 500, while the sensor element 200 and the circuit
board 300 are wired with the bonding wires 500.
[0082] After wire bonding is completed, the package 100 is detached
from above the magnet 800 as shown in FIG. 4C so that the magnetic
force is removed. Then, by welding or brazing the lid 140 to the
package 100, the inside of the package 100 is sealed, thereby
completing the angular velocity sensor device S1 described
above.
[0083] It is also possible to use a magnet such as ferrite to
compose the magnetic member 700 and use a ferromagnetic material
such as iron to compose the magnetic member fixing means below the
package 100 in place of the magnet 800. The arrangement also allows
the same effect to be obtained. To obtain a fixing strength, each
of the magnetic member 700 and the magnetic member fixing means can
also be composed of a magnet.
[0084] The foregoing example shown in FIGS. 3A to 3F and FIGS. 4A
to 4C mounts the sensor module described above on the package 100
via the adhesive agent 400, cures the adhesive agent 400, and then
performs wire bonding. The curing of the adhesive agent 400 may be
also performed after wire bonding.
[0085] In this case, wire bonding is performed with the sensor
module temporarily bonded using the uncured adhesive agent 400
having fluidity. However, during wire bonding, a solidly fixed
structure can be implemented by using the magnetic force of the
magnetic member 700 irrespective of the adhesive agent and a
sufficient bonding property can be obtained.
[0086] In this case, the adhesive agent 400 is cured after wire
bonding. At this time, when the magnetic member 700 and the
magnetic member fixing means are composed of magnets each having
the same polarity, a repelling force acts between the magnetic
member 700 and the package 100. This allows the suppression of the
thinning of the adhesive agent 400 under the weight of the sensor
module and allows the adhesive 400 to retain a sufficient
thickness.
[0087] In the foregoing example shown in FIGS. 3A to 3F and FIGS.
4A to 4C, the magnetic member 700, the circuit board 300, and the
sensor element 200 have been incorporated to produce the sensor
module; then, the sensor module is mounted on the package 100 via
the adhesive agent 400. This order in which the individual
components are mounted on the package 100 is not limited
thereto.
[0088] For example, it is also possible to mount the magnetic
member 700 on the package 100 via the adhesive agent 400,
adhesively mount the circuit board 300 and the sensor element 200
in succession thereon in the state in which the magnetic member 700
is solidly held by using a magnetic force, and then further perform
wire bonding.
[0089] Alternatively, it is also possible to mount the circuit
board 300 with the magnetic member 700 on the package 100 via the
adhesive agent 400, adhesively mount the sensor element 200 thereon
in the state in which the magnetic member 700 and the circuit board
300 are solidly held by using a magnetic force, and then further
perform wire bonding.
[0090] It is to be noted that the completed angular velocity sensor
device S1 is in a normal use state with no magnetic force applied
thereto so that the movement of the sensor element 200 is not
suppressed. Accordingly, the anti-vibration performance of the
adhesive agent 400 is sufficiently exerted as designed.
[0091] Referring primarily to FIG. 2, the sensing operation in such
an angular velocity sensor device S1 will be described.
[0092] A driving signal (sinusoidal voltage or the like) is applied
from the circuit board 300 to the driving electrodes 50 of the
sensor element 200 via the bonding wires 500 to generate an
electrostatic force between the comb-tooth portion 21a of the first
vibrating portion 21 mentioned above and the driving electrodes 50.
As a result, the elastic force of the driving beam portion 23
causes the driving vibration of the first vibrating portion 21 in
the x-direction.
[0093] When an angular velocity Q is applied around the z-axis as a
result of the driving vibration of the first vibrating portion 21,
a Coriolis force is applied in the y-direction to the first
vibrating portion 21 so that the elastic force of the sensing beam
portion 40 causes the sensing vibration of the whole vibrator 20 in
the y-direction.
[0094] As a result, the sensing vibration causes a change in the
capacitance between the respective comb teeth of the sensing
electrodes 60 and the comb-tooth portion 22a for sensing. By
sensing the capacitance change, the magnitude of the angular
velocity .OMEGA. can be determined.
[0095] For instance, when the vibrator 20 is displaced unilaterally
in the y-direction, capacitance changes in opposite directions
occur in the left and right sensing electrodes 60 in FIG. 2. The
capacitance changes in the left and right sensing electrodes 60 are
individually converted to voltages and the two voltage values are
differentially amplified and outputted so that the angular velocity
.OMEGA. is determined.
[0096] Effect, Etc.
[0097] In the angular velocity sensor device S1 as a physical
quantity sensor device, the sensor element 200 for sensing an
angular velocity as a physical quantity is mounted on the package
100 and held thereby via the adhesive agent 400 as an elastic
member having elasticity. The angular velocity sensor device S1 is
characterized in that the magnetic member 700 made of a
ferromagnetic material is provided in the sensor-element-side space
with respect to the adhesive agent 400, as shown in FIG. 1.
[0098] The arrangement allows a magnetic force to act from outside
the package 100 such that the magnetic member 700 is pressed
against the package 100, as described above. By the magnetic force,
the sensor element 200 on the elastic member 400 is more solidly
fixed to the package 100 than when it is merely held by the
adhesive agent 400 as the elastic member 400.
[0099] Thus, the foregoing magnetic force is caused to act during
the assembly or the like and to solidly hold components including
the sensor element 200 mounted on the package 100 via the adhesive
agent 400. It becomes possible to properly mount them on the
adhesive agent 400 and/or perform bonding relative to the
components mounted on the adhesive agent 400. This allows efficient
assembly.
[0100] For instance, the arrangement is effective when wire bonding
is performed relative to the components (including the sensor
element 200) mounted on the adhesive agent 400 as the elastic
member. This is because the magnetic force stabilizes the
supporting of the members to be bonded.
[0101] Subject components mounted on the adhesive agent 400 as the
elastic member are not limited to the sensor element 200 and the
circuit board 300. For example, a component (not shown) mounted as
necessary on the sensor element 200 can be also included in one of
the subject components. When such a component is mounted on the
adhesive agent 400, fixation using the magnetic force as described
above is effective.
[0102] When the angular velocity sensor device S1 is used, the
adhesive agent 400 is allowed to exert the elastic function as
exerted conventionally by removing the magnetic force in the
angular velocity sensor device S1. This allows the anti-vibration
function or the like to be performed and unnecessary vibration
resulting from an external acceleration to be absorbed.
[0103] Thus, this example embodiment allows the angular velocity
sensor device S1 to properly balance the trade-off between the
elastic function and the efficiency in assembly.
[0104] The angular velocity sensor device S1 according to this
example embodiment is characterized in that the magnetic member 700
is interposed between the adhesive agent 400 and the sensor element
200. The arrangement can properly provide the magnetic member 700
in the sensor-element-side space with respect to the adhesive agent
400.
[0105] The angular velocity sensor device S1 according to this
example embodiment is also characterized in that the circuit board
300 is mounted on the package 100 via the adhesive agent 400 as the
elastic member and the sensor element 200 is stacked in fixed
relation onto the circuit board 300, while the magnetic member 700
is interposed between the adhesive agent 400 and the circuit board
300.
Example Embodiment 2
[0106] FIG. 5 is a view showing a schematic cross-sectional
structure of an angular velocity sensor device S2 as a physical
quantity sensor device according to a second example embodiment of
the present invention.
[0107] The angular velocity sensor device S2 according to this
example embodiment is also the angular velocity sensor device, in
which the sensor element 200 is mounted on the package 100 and held
thereby via the adhesive agent 400 as the elastic member. In
addition, the angular velocity sensor device S2 is also
characterized in that the magnetic member 700 is provided in the
sensor-element-side space with respect to the adhesive agent 400,
in the same manner as in the first example embodiment described
above. This arrangement can properly balance the trade-off between
the elastic function and the efficiency in assembly.
[0108] In the first example embodiment described above, the circuit
board 300 and the sensor element 200 are successively stacked on
the package 100 and the magnetic member 700 is interposed between
the circuit board 300 and the adhesive agent 400.
[0109] The present example embodiment is the same as the first
example embodiment described above in the structure in which the
sensor element 200 is stacked on the circuit board 300. In this
example embodiment, however, the circuit board 300 is solidly held
on the package 100 by using a highly rigid adhesive agent not shown
and the adhesive agent 400 as the elastic member is provided
between the circuit board 300 and the sensor element 200. The
arrangement prevents the vibration of the sensor element 200 in the
angular velocity sensor device S2 according to this example
embodiment.
[0110] As shown in FIG. 5, this example embodiment has interposed
the magnetic member 700 between the adhesive agent 400 and the
sensor element 200 in the structure in which the sensor element 200
is stacked on the circuit board 300 via the adhesive agent 400. The
magnetic member 700 is solidly bonded to the sensor element 200 via
the same adhesive agent as used in the example embodiment described
above or the like.
[0111] For example, a method for fabricating the angular velocity
sensor device S2 according to this example embodiment can be
implemented as follows. First, the circuit board 300, the adhesive
agent 400, the magnetic member 700, and the sensor element 200 are
stacked in layers and integrated by curing the adhesive agent 400.
The integrated body is mounted on the package 100 and adhesively
fixed.
[0112] It is also possible to, e.g., mount the circuit board 300
first in fixed relation onto the package 100, stack the adhesive
agent 400 and the sensor element 200 with the magnetic member 700
thereon, and then integrate them by curing the adhesive agent
400.
[0113] In a currently reached state, the sensor element 200 is held
by the soft adhesive agent 400 as the elastic member on the circuit
board 300. Accordingly, when wire bonding is performed, it is
accomplished in the state in which the sensor element 200 is
solidly fixed to the package 100 by using the magnetic force of
each of the magnetic member fixing means and magnetic member 700
described above. The bonding wires 500 are thus formed, in the same
manner as in the example embodiment described above.
[0114] In this example embodiment also, the curing of the adhesive
agent 400 may be also performed after wire bonding. Before wire
bonding, the circuit board 300 and the sensor element 200 are
integrated in the state in which they are temporarily bonded to
each other with the adhesive agent 400 having fluidity. During wire
bonding, however, a sufficient bonding property can be obtained by
using the magnetic force of the magnetic member 700.
[0115] Thereafter, the removal of the magnetic force, the
attachment of the lid 140 to the package 100, and the like are
performed in the same manner as in the example embodiment described
above, whereby the angular velocity sensor device S2 according to
this example embodiment is completed.
[0116] It will be easily understood that, in this example
embodiment also, the magnetic member 700 and the like can be
variously modified as shown in the example embodiment described
above.
Example Embodiment 3
[0117] FIG. 6 shows a schematic cross-sectional structure of an
angular velocity sensor device S3 as a physical quantity sensor
device according to a third example embodiment of the present
invention.
[0118] The angular velocity sensor device S3 according to this
example embodiment is also the angular velocity sensor device in
which the sensor element 200 is mounted on the package 100 and held
thereby via the adhesive agent 400 as the elastic member. In
addition, the angular velocity sensor device S3 is also
characterized in that the magnetic member 700 is provided in the
sensor-element-side space with respect to the adhesive agent 400,
similarly to the first example embodiment. The arrangement can
properly balance the trade-off between the elastic function and the
efficiency in assembly.
[0119] As shown in FIG. 6, the magnetic member 700 according to
this example embodiment includes (i) a first magnetic member 710
located in a first space and (ii) a second magnetic member 720
located in a second space. The first and second spaces are defined
with respect to the adhesive agent 400 as the elastic member,
similarly in the first example embodiment. The adhesive agent 400
faces the first space (sensor-element-side space) that includes the
sensor element 200, while the adhesive agent 400 faces the second
space that does not include the sensor element 200 (e.g., in FIG.
6, the second space (package-side space) includes the bottom of the
package 100). In other words, the first magnetic member 710 is
closer to the sensor element 200 than the adhesive agent 400; the
second magnetic member 720 is closer to the bottom of the package
100 than the adhesive agent 400. The first and second magnetic
members 710 and 720 are opposing each other via the adhesive agent
400; namely, the adhesive agent 400 is disposed or interposed
between the first and second magnetic members 710 and 720.
[0120] For instance, the circuit board 300 is mounted on the
package 100 and the sensor element 200 is fixed to an upper surface
thereof by using a hard adhesive agent, an adhesive film, or the
like which is not shown. On the other hand, the magnetic member 700
including the first and second magnetic members 710 and 720 is
interposed between the circuit board 300 and the package 100.
[0121] In FIG. 6, the upper first magnetic member 710 is solidly
fixed to the circuit board 300, while the lower second magnetic
member 720 is solidly fixed to the package 100, each by using a
hard adhesive agent or the like which is not shown.
[0122] The adhesive agent 400 as the elastic member is interposed
between the first and second magnetic members 710 and 720 to
provide adhesion between the two magnetic members 710 and 720.
Thus, the angular velocity sensor device S3 according to this
example embodiment has a structure obtained by adding, in the
foregoing structure shown in FIG. 1, another magnetic member in the
second space facing the package 100 with respect to the adhesive
agent 400. In this case also, elasticity is exerted by the adhesive
agent 400 and vibration is restricted.
[0123] By disposing the two magnetic members 710 and 720 in
opposing relation with the adhesive agent 400 interposed
therebetween as in this example embodiment, a magnetic circuit can
be formed between the two magnetic members 710 and 720.
[0124] The sensor element 200 and the circuit board 300 may be
influenced by an electromagnetic force resulting from residual
magnetism after processing. However, the structure makes it
possible to suppress the leakage of a magnetic field toward the
circuit board 300 and the sensor element 200 through the formation
of the magnetic circuit mentioned above. Thus, this example
embodiment allows the minimization of the magnetic influence of the
magnetic member 700.
[0125] In addition, in the angular velocity sensor device S3
according to this example embodiment, a protruding portion 730 is
provided by an embossing finish or the like at a portion of the
second magnetic member 720 of the mutually opposing portions of the
first and second magnetic opposing members 710 and 720, as shown in
FIG. 6.
[0126] The protruding portion 730 allows the adhesive agent 400 as
the elastic member to retain a thickness between the two magnetic
members 710 and 720. When the two magnetic members 710 and 720 are
caused to approach each other within a given distance by the
magnetic force, the protruding portion 730 functions as a stopper
to prevent the adhesive agent 400 from sinking under the magnetic
force. This allows the adhesive agent 400 to retain a proper
thickness.
[0127] Although the protruding portion 730 is provided only at the
second magnetic member 720 in the example shown in FIG. 6, the
protruding portion may be also provided only at the first magnetic
member 710 or at each of the first and second magnetic members 710
and 720.
[0128] In other words, the protruding portion may be provided
appropriately at at least one of the mutually opposing portions of
the first and second magnetic members 710 and 720 so long as it
functions as a stopper to prevent the adhesive agent 400 from
sinking under the magnetic force and allows the adhesive agent 400
to retain a proper thickness. Alternatively, multiple protruding
portions may be also provided.
Example Embodiment 4
[0129] FIG. 7 is a view showing a schematic cross-sectional
structure of an angular velocity sensor device S4 according to a
fourth example embodiment of the present invention. The present
example embodiment has been obtained by partly modifying the device
having the first and second magnetic members 710 and 720 according
to the third example embodiment described above.
[0130] The angular velocity sensor device S4 according to this
example embodiment also allows the trade-off between the elastic
function and the assemblability to be properly balanced by
providing the magnetic member 700 in the sensor-element-side space
facing the sensor element 200 with respect to the adhesive agent
400. Furthermore, similarly to the third example embodiment, the
magnetic member 700 includes two mutually opposing first and second
magnetic members 710 and 720. The first magnetic member 710 is in
the first space with respect to the adhesive agent 400, while the
second magnetic member 720, in the second space. The first space
includes the sensor element 200, while the second space includes
the bottom of the package 100, as shown in FIG. 7.
[0131] Accordingly, in the angular velocity sensor device S4
according this example embodiment also, a magnetic circuit can be
formed between the two magnetic members 710 and 720 and the
magnetic influence of the magnetic member 710 can be minimized.
[0132] In this example embodiment, an end portion of the first
magnetic member 710 is provided with a protruding (or projecting)
portion 740 that overhangs from an end portion of the second
magnetic member 720 to project toward the package 100, as shown in
FIG. 7.
[0133] The projecting portion 740 is configured as a bent portion
formed by bending the end portion of the first magnetic member 710.
To allow the adhesive agent 400 to retain a thickness between the
two magnetic members 710 and 720, the projecting length of the
projecting portion 740 is adjusted to be larger than a thickness of
the adhesive agent 400.
[0134] In the arrangement, when the first magnetic member 710 is
caused to approach the package 100 within a given distance by the
magnetic force, the projecting portion 740 comes in contact with
the package 100 to function as a stopper. Accordingly, this example
embodiment can also prevent the adhesive agent 400 from sinking
under the magnetic force and allows the adhesive agent 400 to
retain a proper thickness. Furthermore, the projecting portion 740
can be alternatively provided at a portion of the first magnetic
member 710 instead of the end portion of the first magnetic member
710. For instance, the projecting portion 740 can be provided in
any portion of the first magnetic member 710 as long as the
projecting portion 740 comes in contact with the package 100
without being intervened by the second magnetic member 720, e.g.,
through a through-hole provided in the second magnetic member
720.
Other Example Embodiments
[0135] Although the magnetic members 710 and 720 are interposed
between the circuit board 300 and the package 100 in each of the
angular velocity sensor devices which uses the magnetic member 700
composed of the first and second magnetic members 710 and 720
described above, the magnetic members 710 and 720 may be also
interposed between the circuit board 300 and the sensor element
200.
[0136] In each of the angular velocity sensor devices which uses
the magnetic member 700 composed of the first and second magnetic
members 710 and 720, at least one of the mutually opposing portions
of the first and second magnetic members 710 and 720 may have the
foregoing protruding portion 730. In addition, the projecting
portion 740 may be also provided at the end portion of the first
magnetic member 710. In other words, it is also possible to prevent
the adhesive agent 400 from sinking under the magnetic force and
allow the adhesive agent 400 to retain a thickness by making
effective use of each of the functions of the protruding and
projecting portions described above.
[0137] When the vibrator 20 of the sensor element 200 is
electro-magnetically driven in each of the example embodiments
described above, the magnetic member 700 can be used as a source
for generating a magnetic field therefor. In this case, since the
magnetic field should be positively generated, the structure can be
made more compact by mounting the magnetic member 700 as a
magnet.
[0138] A package is not limited to the ceramic package described
above. The configuration of the package is not limited to the
foregoing examples shown in the drawings.
[0139] Although the angular velocity sensor device has been
described heretofore as an example of the physical quantity sensor
device according to the present invention, the present invention is
not limited to an angular velocity sensor and is also applicable to
an acceleration sensor, a pressure sensor, a temperature sensor, a
humidity sensor, an optical sensor, an image sensor, or the
like.
[0140] In other words, in each of the example embodiments described
above, the foregoing sensor element 200 may be also an acceleration
sensing element, a pressure sensing element, a temperature sensing
element, a humidity sensing element, an optical sensing element, or
an image sensing element.
[0141] As the circuit board, any circuit such as a circuit using a
MOS transistor, a bipolar transistor, or the like, a memory
circuit, or the like may be used. In the physical quantity sensor
device according to the present invention, the circuit board need
not be provided and the sensor element may be attached directly to
the package via the adhesive agent as the elastic member.
[0142] In this case, the magnetic member may be provided
appropriately between the adhesive agent and the sensor element.
The elastic member is not limited to the adhesive agent made of a
resin described above. Otherwise, the elastic member may be also
composed of, e.g., rubber, a low-elasticity adhesive film, or the
like.
[0143] It will be obvious to those skilled in the art that various
changes may be made in the above-described embodiments of the
present invention. However, the scope of the present invention
should be determined by the following claims.
* * * * *