Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-03-03
2001-01-09
Mayes, Curtis (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S089120, C156S089160, C156S089280
Reexamination Certificate
active
06171420
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a manufacturing process of a functional film element, and, more particularly, to a manufacturing process of a functional film element suitably used for a fluid sensor, a temperature sensor, a fluid pump, a speaker, an actuator, a transducer or the like.
In recent years, there has been known a functional film element utilizing an energy conversion function of a functional film, in which a cavity is formed in a substrate, and a functional film actuator is mounted on the outer surface of the cavity, whereby the functional film actuator senses change of physical variable such as pressure or temperature occurring in the cavity, and outputs an electric signal corresponding to the variation of that physical variable. A functional film element utilizing such characteristics for converting variation of various physical variables into an electric signal is generally called a functional film sensor or a functional filter.
Contrary to the above, when an electric signal (voltage or current) is applied to such functional film element, the functional film actuator generates mechanical stress such as expansion and contraction, bending or vibration in the cavity according to the applied voltage or current, or generates heat so that it acts as a heater or the like for heating inside the cavity.
FIG. 4
shows an example of structure of a conventional functional film element
14
or a sensor. A functional film element
14
is constituted by providing through holes
2
and
3
to input the variable to be measured, forming in a ceramics substrate
9
a cavity
1
which is a measurement area, and integrally forming a functional film actuator
13
on a covering plate
6
for the external wall positioned opposite to the through holes
2
and
3
in the cavity
1
. Here, the ceramics substrate
9
is integrally formed by laminating the covering plate
6
and a through hole plate
8
having the through holes
2
and
3
passing into the cavity
1
, each of which is a very thin plate, with a window spacer plate
7
therebetween. The through holes are not limited to the through holes
2
and
3
, but a through hole
4
or other through holes are provided depending on an object to increase contact points with the external environment.
The window spacer plate
7
is formed with a window
5
in such a manner that three through holes
2
,
3
and
4
provided in the through hole plate
8
are formed in a longitudinal extent of the window
5
so that these holes are opened toward the window
5
. In addition, a very thin covering plate
6
is laminated on a surface opposite to the side on which the through hole plate
8
of the window spacer plate
7
is laminated to cover and close the window
5
, thereby forming the cavity
1
within the ceramics substrate
9
.
Then, the ceramics substrate
9
is provided with the functional film actuator
13
on the outer surface of the covering plate
6
at a position corresponding to the cavity
1
. Here, the functional film actuator
13
consists of a lower electrode
12
, a functional film layer
11
, and an upper electrode
10
.
The conventional functional element
14
is arranged as above, in which, viewing the cavity
1
and the through holes
2
,
3
and
4
in a plan view, the cavity
1
overlaps over the through holes
2
,
3
and
4
as shown in FIG.
5
. On the other hand, in recent years, as seen in a plan view of
FIG. 2
showing a positional relationship between a window
29
, and through holes
22
,
23
and
24
, there has been employed, to enhance detection accuracy of the functional film element, a shape in which through holes, for example,
22
and
23
out of those formed in the ceramics substrate are longitudinally elongated in a cavity
21
(window
29
).
However, in actually manufacturing a functional film element to have the through holes
22
and
23
outwardly elongated from the outer edge of the cavity
21
(window
29
), when ceramics green sheets are laminated and integrated under pressure, the through holes
22
and
23
provided through a window spacer plate
26
and a through hole plate
27
prevent transmission of pressure through each green sheet in the laminating direction, thereby making it difficult to apply sufficient pressing pressure, and sufficient adhesion cannot be obtained. Consequently, there is a problem in that a covering plate
25
and a window spacer plate
26
are separated at an adhered section between them facing the window
21
to generate a gap
41
after firing as shown in FIG.
3
.
Generation of such gap
41
is unfavorable since when the functional film element is used as a pressure measuring sensor, air is left in the cavity when fluid to be measured for pressure is intended to be filled in the cavity to provide a pressure measurement error. In addition, when it is used as a temperature sensor, in measuring temperature of fluid such as liquid, air left in the gap frequently has thermal capacity different from that of the liquid, and the air causes delay of measurement accurately following temperature variation of the liquid. In addition, when it is used for a speaker, mechanical stress is imposed on the covering plate
25
due to vibration of the functional film element. This causes separation of the covering plate
25
or the like to proceed with the gap
41
as a starting point of breakage. As a result the speaker will break.
SUMMARY OF THE INVENTION
The present invention is made in view of the problems as described above, and the object of the present invention is to provide a process of manufacturing a functional film element in which through holes are elongated outward from a cavity, wherein gap is generated between a covering plate and a window spacer plate.
To attain the above object, according to the present invention, there is provided a process of manufacturing a functional film element, which comprises the steps of:
placing a covering plate on one side of a window spacer plate, which is provided with at least one window, to cover and close the window;
placing a through hole plate with through holes on the other side of the window spacer plate so that at least parts of said through holes communicate with the window, and the through holes are elongated outward from the window;
laminating and integrally firing green sheet of each of the plates in such a manner that a ratio t/w of thickness t of the window spacer plate to width w of the through hole in its minor axis direction is one or more; to produce a ceramics substrate formed with a cavity in which the through holes communicate with the window; and
forming a functional film on the outer surface of the covering plate.
In the process of manufacturing a functional film element, the through hole is preferably formed with a width of 300 &mgr;m or less in the direction of minor axis in the green sheet for the through hole plate. The through hole preferably has a shape of elongated circle, oval or rectangular.
According to the process of manufacturing a functional film element according to the present invention, a gap is prevented from being generated at an interface between the covering plate and the window spacer plate in producing the ceramics substrate of the functional film element, thereby a functional film element being provided with excellent detection accuracy and mechanical properties.
Here, the functional film herein specifically means a dielectric film, a thermoelectric element film, a piezoelectric/electrostrictive film, a varistor film, or a film consisting of only electrodes.
REFERENCES:
patent: 5376856 (1994-12-01), Takeuchi et al.
patent: 5512793 (1996-04-01), Takeuchi et al.
patent: 5617127 (1997-04-01), Takeuchi et al.
patent: 5643379 (1997-07-01), Takeuchi et al.
patent: 5670999 (1997-09-01), Takeuchi et al.
patent: 5728244 (1998-03-01), Nanataki et al.
patent: 5733670 (1998-03-01), Takeuchi et al.
patent: 5893954 (1999-04-01), Nanataki et al.
patent: 0 572 230 (1993-12-01), None
patent: 640035 (1994-02-01), None
Nanataki Tsutomu
Takahashi Nobuo
Mayes Curtis
NGK Insulators Ltd.
Wall Marjama Bilinski & Burr
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