U.S. patent application number 11/355772 was filed with the patent office on 2006-06-29 for vibrator support structure and manufacturing method for the support structure.
Invention is credited to Katsumi Fujimoto, Masato Koike.
Application Number | 20060137815 11/355772 |
Document ID | / |
Family ID | 32828961 |
Filed Date | 2006-06-29 |
United States Patent
Application |
20060137815 |
Kind Code |
A1 |
Koike; Masato ; et
al. |
June 29, 2006 |
Vibrator support structure and manufacturing method for the support
structure
Abstract
In a vibrator support structure, a vibrator is supported on a
substrate through support pins, substrate connection portions of
the support pins and pin connection portions of the substrate are
joined through conductive adhesive which is made of a resin
including conductive filler and has a pencil hardness of about 4H
or less, and the conductive adhesive has a thickness which can
buffer vibrations and impacts propagated through the support
pins.
Inventors: |
Koike; Masato; (Toyama-ken,
JP) ; Fujimoto; Katsumi; (Toyama-ken, JP) |
Correspondence
Address: |
MURATA MANUFACTURING COMPANY, LTD.;C/O KEATING & BENNETT, LLP
8180 GREENSBORO DRIVE
SUITE 850
MCLEAN
VA
22102
US
|
Family ID: |
32828961 |
Appl. No.: |
11/355772 |
Filed: |
February 16, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10735704 |
Dec 16, 2003 |
|
|
|
11355772 |
Feb 16, 2006 |
|
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Current U.S.
Class: |
156/278 ;
156/327 |
Current CPC
Class: |
H05K 2201/10628
20130101; G01C 19/5663 20130101; H05K 2201/10848 20130101; Y02P
70/50 20151101; H05K 2201/10083 20130101; H01L 41/053 20130101;
H05K 3/321 20130101; H05K 2201/10757 20130101; H05K 3/3426
20130101; H05K 2201/2045 20130101; Y02P 70/613 20151101 |
Class at
Publication: |
156/278 ;
156/327 |
International
Class: |
B32B 37/00 20060101
B32B037/00; B32B 7/12 20060101 B32B007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2003 |
JP |
2003-034124 |
Oct 2, 2003 |
JP |
2003-343970 |
Claims
1. A method of manufacturing a vibrator support structure
comprising the steps of: providing a vibrator which is supported on
a substrate through support pins; and hardening conductive adhesive
for joining a substrate connection portion of the support pins and
a pin connection portion of the substrate, the conductive adhesive
existing therebetween, while only the weight of the vibrator and
the support pins is applied.
2. A method of manufacturing a vibrator support structure as
claimed in claim 1, further comprising the step of coating each of
the substrate connection portion and the pin connection portion
with conductive adhesive in advance for joining the substrate
connection portion of the support pins and the pin connection
portion of the substrate.
3. A method of manufacturing a vibrator support structure as
claimed in claim 1, wherein the conductive adhesive is made of
resin including a conductive filler and has a pencil hardness of
about 4H or less.
4. A method of manufacturing a vibrator support structure as
claimed in claim 1, wherein the conductive adhesive has a thickness
that is sufficient to buffer vibrations and impacts propagated
through the support pins.
Description
[0001] This application is a Divisional Application of U.S. patent
application Ser. No. 10/735,704 filed Dec. 16, 2003, currently
pending.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a vibrator support
structure and to a method of manufacturing the support
structure.
[0004] 2. Description of the Related Art
[0005] Up to now, in vibrating gyroscopes, a vibrator support
structure provided with a vibrator having a bending vibration mode,
support pins for supporting the vibrator, and a substrate on which
the vibrator is mounted through the support pins has been adopted.
That is, in the vibrator, a pair of piezoelectric substrates
oppositely polarized in the thickness direction are joined so as to
face each other, and one piezoelectric substrate, on which first
and second detector electrodes are formed so as to be separated
from each other, and the other piezoelectric substrate, on the
entire surface of which a drive electrode is formed, are joined so
as to sandwich an intermediate electrode.
[0006] Then, the support pins are attached to the first and second
detector electrodes at locations corresponding to vibration nodal
points and also the support pins are attached to the drive
electrode at locations corresponding to vibration nodal points.
Furthermore, a substrate connection portion, which is an outer end
portion of each support pin, is joined to each pin connection
portion provided on the substrate by soldering. Accordingly, the
vibrator is mounted on the substrate through the support pins and
is supported so as to be able to perform bending vibration (see
Japanese Unexamined Patent Application Publication No. 2001-227953,
for example).
[0007] Moreover, in another vibrator support structure, a substrate
connection portion, which is an outer end portion of an L-shaped
support pin, is inserted into a through-hole of an attachment part
which is not the substrate, and the substrate connection portion of
the support pin is fixed to the attachment part by soldering. In
this support structure, a separate buffer material is placed
between the attachment part and the substrate (see Japanese
Unexamined Patent Application Publication No. 6-221854 and Japanese
Unexamined Patent Application Publication No. 6-258082, for
example).
[0008] In the vibrator support structures of the related art, the
substrate connection portion of the support pins and the pin
connection portion of the substrate are joined by soldering.
However, since the solder, which is a metal, is solidified and
hardens, vibrations leaking from the vibrator are easily propagated
to the substrate through the support pins and a residual stress is
easily caused in the support pins. Furthermore, in such a support
structure, it becomes easy for impacts applied to the substrate
from the outside to be directly propagated to the vibrator through
the support pins.
[0009] On the other hand, in a vibrator support structure in which
an attachment part fixed on a substrate with a buffer material
therebetween and a substrate connection portion of a support pin
are soldered, there is an advantage in that the vibrations and
impacts propagated through the support pin are weakened by the
buffer material. However, the fact is that, since it is necessary
to place a buffer material between the attachment part and the
substrate, the number of parts increases and the structure becomes
complicated, and, as a result, this requires additional during the
assembling process.
[0010] Moreover, as long as a vibrator support structure using
soldering is adopted, reflow mounting of a vibrating gyroscope
accompanied by the re-melting of solder cannot be avoided.
Accordingly, the trouble of changing the balance between parts in
the vibrator support structure, that is, damage of support
conditions due to the release of residual stress, etc., is likely
to occur.
SUMMARY OF THE INVENTION
[0011] In order to overcome the problems described above, preferred
embodiments of the present invention provide a vibrator support
structure in which vibrations and impacts propagated through
support pins are buffered, and also provide a method of
manufacturing such a novel vibrator support structure.
[0012] A vibrator support structure according to a first preferred
embodiment of the present invention includes a vibrator, a
substrate, and support pins. In the support structure of a
vibrator, the vibrator is supported on the substrate through the
support pins, substrate connection portions of the support pins and
pin connection portions of the substrate are joined through a
conductive adhesive which is made of resin including a conductive
filler and has a pencil hardness of about 4H or less, and the
conductive adhesive has a thickness which can buffer vibrations and
impacts propagated through the support pins. Accordingly, the
propagation of a vibration leaking from the vibrator to the
substrate through the support pins and the propagation of impacts
applied to the vibrator from the outside through the support pins
are effectively suppressed. Therefore, without providing any
separate buffer material, the occurrence of residual stress to the
support pins and damage of the vibrator can be prevented.
Furthermore, when constructed in this way, variations in height
(co-planarity) of the support pins can be compensated for.
[0013] In a vibrator support structure of preferred embodiments of
the present invention, an opening allowing conductive adhesive
existing between the vibrator connection portion of the support
pins and the vibrator to ooze out is provided in the vibrator
connection portion of the support pins.
[0014] In a vibrator support structure of preferred embodiments of
the present invention, an opening allowing conductive adhesive
existing between the substrate connection portion of the support
pins and the pin connection portion of the substrate to ooze out is
provided in the substrate connection portion of the support pins.
When the opening is provided, since the contacting area between the
conductive adhesive and the support pins increases, the vibrator
connection portion of the support pins and the vibrator or the
substrate connection portion of the support pins and the pin
connection portion of the substrate can be more strongly
joined.
[0015] A method of manufacturing a vibrator support structure
according to another preferred embodiment of the present invention
includes the step of hardening conductive adhesive for joining the
substrate connection portion of the support pins and the pin
connection portion of the substrate, the conductive adhesive
existing therebetween, while only the weight of the vibrator and
the support pins is applied. Accordingly, no residual stress occurs
in the support pins after the conductive adhesive has been hardened
and a sufficient thickness of the conductive adhesive can be
obtained to buffer vibrations and impacts.
[0016] A manufacturing method for a vibrator support structure of
various preferred embodiments of the present invention preferably
further includes the step of coating each of the substrate
connection portion and the pin connection portion with conductive
adhesive in advance for joining the substrate connection portion of
the support pins and the pin connection portion of the substrate.
Accordingly, a sufficient quantity of conductive adhesive can be
placed between the substrate connection portion and the pin
connection portion. Therefore, it becomes possible to arrange the
conductive adhesive to effectively buffer vibrations and
impacts.
[0017] Other features, elements, characteristics, steps and
advantages of the present invention will become more apparent form
the following detailed description of preferred embodiments with
reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a side view showing the assembled state of a
vibrator support structure of according to a preferred embodiment
of the present invention;
[0019] FIG. 2 is a perspective view showing the disassembled state
of the vibrator support structure according to a preferred
embodiment of the present invention;
[0020] FIG. 3 is an expanded perspective view showing support pins
according to a preferred embodiment of the present invention;
[0021] FIG. 4 shows the temperature characteristics of drift of a
vibrating gyroscope in which the vibrator support structure
according to a preferred embodiment of the present invention is
adopted; and
[0022] FIG. 5 shows the temperature characteristics of drift of a
vibrating gyroscope in which the vibrator support structure
according to a preferred embodiment of the present invention is
adopted after the vibrating gyroscope has been reflow-mounted.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] FIG. 1 is a side view showing the assembled state of a
vibrator support structure according to a preferred embodiment of
the present invention, FIG. 2 is a perspective view showing the
disassembled state of the vibrator support structure according to
the present preferred embodiment, and FIG. 3 is an expanded
perspective view showing support pins according to the present
preferred embodiment. FIGS. 4 and 5 show temperature
characteristics of drift of vibrating gyroscopes. The temperature
characteristics of drift means the change in output at rest while
no angular velocity is applied, that is, the change in output
versus temperature at rest. Moreover, in FIGS. 4 and 5, the
vertical axis represents output (V) at rest and the horizontal axis
represents temperature (.degree. C.).
[0024] The vibrator support structure according to the present
preferred embodiment is adopted in vibrating gyroscopes, etc., and,
as shown in FIGS. 1 and 2, includes a vibrator 1 preferably in the
form of a substantially rectangular solid having a bending
vibration mode, four support pins 2 and 3 for supporting the
vibrator 1, and a substrate 4 on which the vibrator 1 is mounted
through the support pins 2 and 3. Moreover, the support pins 2 and
3 are made of a thin metal plate and are bent into the shapes shown
in FIGS. 2 and 3.
[0025] In the vibrator 1, a pair of piezoelectric substrates 5 and
6, which are oppositely polarized in the thickness direction, are
joined together, and a drive electrode (not illustrated) is
arranged on the entire outer surface of one piezoelectric substrate
5. On the outer surface of the other piezoelectric substrate 6,
first and second detector electrodes (not illustrated), which are
separate from each other, are formed, and the inner surfaces of the
piezoelectric substrates 5 and 6 are joined so as to sandwich an
intermediate electrode (not illustrated).
[0026] Vibrator connection portions 2a of the support pins 2 are
joined to locations corresponding to vibration nodal points of the
drive electrode disposed on the piezoelectric substrate 5 by using
conductive adhesive, that is, a conductive adhesive made of resin
containing a conductive filler and having the same hardness as a
pencil hardness of approximately 4H or less. Also, vibrator
connection portions 3a of the support pins 3 are joined to
locations corresponding to vibration nodal points at the first and
second detector electrodes disposed on the piezoelectric substrate
6 using the conductive adhesive (not illustrated).
[0027] That is, the support pins 2 and 3 include the vibrator
connection portions 2a and 3a in the width direction of the
vibrator 1, substrate connection portions 2b and 3b facing the
substrate 4, and connection portions 2c and 3c which are extended
in a direction so as to move away from the vibrator 1 and bent
downward or upward after being extended in the length direction of
the vibrator 1 and bent downward. Moreover, SA2024 (product name)
produced by Fujikura Kasei Co., Ltd. can be given as a specific
example of the conductive adhesive used in the present preferred
embodiment.
[0028] In each of the vibrator connection portions 2a and 3a of the
support pins 2 and 3, an opening 7 such as a round hole, etc.,
which allows the conductive adhesive between the vibrator
connection portions 2a or 3a and the vibrator 1 to ooze out is
provided. So, the conductive adhesive existing between the vibrator
conductor portions 2a and 3a of the support pins 2 and 3 and the
vibrator 1 oozes out through each opening 7 and runs to the outer
surface of the vibrator connection portions 2a and 3a which do not
face the vibrator 1 and hardens. As a result, the vibrator
connection portions 2a and 3a of the support pins 2 and 3 and the
vibrator 1 are securely joined by the conductive adhesive which
continues to maintain a certain level of elasticity after the
hardening. Moreover, the opening 7 is not limited to a round hole,
but may be a square hole, a cut groove, etc.
[0029] Furthermore, the substrate connection portions 2b and 3b,
which are outer end portions of the support pins 2 and 3 for
supporting the vibrator 1, are joined to the pin connection
portions 4a which are positioned and formed on the mounting surface
of the substrate 4 so as to correspond to the substrate connection
portions 2b and 3b by using conductive adhesive existing
therebetween. At this time, the conductive adhesive 8 for joining
the substrate connection portions 2b and 3b of the support pins 2
and 3 to the pin connection portions 4a of the substrate 4 has a
thickness which can sufficiently buffer the vibrations and impacts
propagated through the support pins 2 and 3, that is, the thickness
between the substrate connection portions 2b and 3b and the pin
connection portions 4a.
[0030] Moreover, although not illustrated, the substrate connection
portions 2b and 3b of the support pins 2 and 3 may be provided with
the same type of opening as the vibrator connection portions 2a and
3a. When such an opening is provided, since the conductive adhesive
existing between the substrate connection portions 2b and 3b of the
support pins 2 and 3 and the pin connection portions 4a of the
substrate 4 oozes out through the opening, it becomes possible to
securely join the substrate connection portions 2b and 3b and the
pin connection portions 4a.
[0031] That is, when the above-described support structure, in
which the vibrator 1 is mounted on the substrate 4 through the
support pins 2 and 3, is used in a vibrating gyroscope and a signal
is input between each of the detector electrodes and the drive
electrode, the vibrator 1 performs bending vibration in a direction
which is substantially perpendicular to the surface where the drive
electrode is formed. Furthermore, when a rotational force is
applied to the vibrator 1, the vibration direction changes because
of the Coriolis force and a signal corresponding to the change of
the vibration direction is output from the detector electrodes.
Therefore, when the output signal is measured, a rotational angular
velocity applied to the vibrator 1 can be detected.
[0032] On the other hand, when the support structure of the
vibrator 1 according to the present preferred embodiment is
manufactured, the following assembly process is preferably adopted.
First of all, the vibrator connection portions 2a and 3a of the
support pins 2 and 3 are joined to the top and bottom surfaces,
respectively, of the vibrator 1 using conductive adhesive. Next,
the substrate connection portions 2b and 3b of the support pins 2
and 3 joined to the vibrator 1 are coated with a sufficient
quantity of conductive adhesive 8. Then, the substrate conduction
portions 2b and 3b of the support pins 2 and 3 coated with the
conductive adhesive 8 are positioned on the respective pin
connection portions 4a of the substrate 4 and held.
[0033] After that, the conductive adhesive 8 existing between the
substrate connection portions 2b and 3b and the pin connection
portions 4a is hardened while only the weight of the vibrator 1 and
support pins 2 and 3 is applied. At this time, since no external
force other than the height of the vibrator 1 and the support pins
2 and 3 is applied to the conductive adhesive 8, the hardened
conductive adhesive 8 has a sufficient thickness for buffering
vibrations and impacts propagating through the support pins 2 and 3
and there is no residual stress left in the support pins 2 and
3.
[0034] Accordingly, the propagation of vibrations leaking from the
vibrator 1 through the support pins 2 and 3 and the direct
propagation of impacts applied to the substrate 4 to the vibrator 1
through the support pins 2 and 3 are suppressed by the conductive
adhesive 8, which continues to maintain sufficient elasticity after
hardening. Moreover, in the present preferred embodiment, although
preferably only the substrate connection portions 2b and 3b of the
support pins 2 and 3 are coated with the conductive adhesive 8, as
shown in FIG. 2, each of the substrate connection portions 2b and
3b and the pin connection portions 4a may be coated with half of
the conductive adhesive 8a and 8b, and then, it becomes possible to
easily apply a sufficient quantity of the conductive adhesive
8.
[0035] Now, although the support structure of the vibrator 1 is
adopted in a vibrating gyroscope, it is known that the stability of
vibrating gyroscopes is judged by temperature characteristics of
drift, and it is desirable that, regarding the temperature
characteristics of drift, the output at rest or stationary state be
flat in the measurement temperature range. So, the inventor of the
present invention and others have measured the temperature
characteristics of drift of two vibrating gyroscopes in which the
support structure of the vibrator 1 described in the present
preferred embodiment is used, and the result of the measurement was
obtained as shown in FIG. 4. That is, in the vibrating gyroscopes A
and B which adopted the support structure according to the present
preferred embodiment, it was discovered that the output at rest is
flat in the measurement temperature range and the support structure
of the vibrator 1 is stable.
[0036] Furthermore, when a vibrating gyroscope is reflow-mounted,
there was a fear that the support structure of the vibrator 1 may
become unstable, but, when the inventor of the present invention
and others made measurements of the temperature characteristics of
drift of the vibrating gyroscopes A and B after they were
reflow-mounted, the measurement results shown in FIG. 5 were
obtained. According to these measurement results, the temperature
characteristics of drift were not deteriorated by the reflow
mounting, and, since the support structure of the vibrator 1
continued to be stable, the balance between the parts did not
change; that is, the support condition did not change by the
release of residual stress, etc. Moreover, the support structure of
the vibrator 1 is applied to not only vibrating gyroscopes, but can
also be applied to other electronic components.
[0037] In Japanese Unexamined Patent Application Publication No.
2000-146593, it is disclosed that the leakage of vibration to the
support pins from the vibrator can be prevented by connecting the
vibrator and the support pins through conductive adhesive. In this
case, the conductive adhesive mainly acts as a buffer for the
vibration, and it may be said that it is analogous to the
contraction of preferred embodiments of the present invention in
that the conductive adhesive is utilized as a vibration buffer.
However, when the pencil hardness is low, the increased viscosity
may prevent the vibrator from vibrating. Accordingly, when the
vibrator and the support pins are joined, it becomes necessary to
set the lower limit of the pencil hardness so as not to prevent the
vibrator from vibrating.
[0038] On the other hand, in the case of preferred embodiments of
the present invention, the main portion of the vibration buffer is
the support pins and the connection portion between the support
pins and the substrate constitutes the remainder of the function of
the vibration buffer. Therefore, the lower limit of the pencil
hardness is not particularly defined. That is, the present
invention and the technology described in Japanese Unexamined
Patent Application Publication No. 2000-146593 are not the
same.
[0039] The present invention is not limited to each of the
above-described preferred embodiments, and various modifications
are possible within the range described in the claims. An
embodiment obtained by appropriately combining technical features
disclosed in each of the different preferred embodiments is
included in the technical scope of the present invention.
* * * * *