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DESCRIPTION JP2015160104

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DESCRIPTION JP2015160104
Abstract: The present invention provides an ultrasonic device unit capable of sufficiently
attenuating ultrasonic waves on the back side of a vibrating membrane even if the substrate is
thinned. An ultrasonic device unit (DV) has an element array including a plurality of thin film
ultrasonic transducer elements arranged in an array on a first surface, and an ultrasonic device
unit (DV) is provided for each thin film ultrasonic transducer element. The first substrate 44 is
provided with an opening 46 that opens in the second surface on the back side of one surface.
The second substrate 53 is coupled to the second surface of the first substrate 44. The second
substrate 53 has a through hole continuous with the opening 46 with a width that
accommodates at least the contour of the element array in a plan view from the thickness
direction of the first substrate 44. [Selected figure] Figure 3
Ultrasonic device unit and probe, electronic apparatus and ultrasonic imaging apparatus
[0001]
The present invention relates to an ultrasonic device unit, a probe using the same, an electronic
device, an ultrasonic imaging apparatus and the like.
[0002]
As disclosed in U.S. Pat. No. 5,958,015, ultrasound devices comprising ultrasound transducer
elements are generally known.
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The ultrasonic transducer element includes a substrate having an element array including a
plurality of ultrasonic transducer elements arranged in an array on a first surface. Each
ultrasonic transducer element comprises a vibrating membrane. An opening is formed in the
substrate when forming the vibrating film. The opening opens at a second surface on the back
side of the first surface.
[0003]
JP, 2013-211604, A
[0004]
In Patent Document 1, the back plate is bonded to the second surface of the substrate.
The back plate closes the opening of the substrate. At this time, further thinning of the
ultrasound device is expected for some ultrasound devices. As the thinning of the substrate
progresses along with this, the depth of the opening decreases. The distance from the vibrating
membrane to the back plate is shortened, and as a result, there is a concern about the reflection
of ultrasonic waves propagating through the air in the opening. The ultrasonic waves that can
not be attenuated are reflected at the interface of the back plate and act on the vibrating film,
which adversely affects the ultrasonic measurement.
[0005]
In view of these circumstances, it is desirable to provide an ultrasonic device unit capable of
sufficiently attenuating ultrasonic waves on the back side of the diaphragm even if the substrate
is thinned.
[0006]
(1) One aspect of the present invention has an element array including a plurality of thin film
type ultrasonic transducer elements arranged in an array on the first surface, and the abovementioned per thin film type ultrasonic transducer element A first substrate having an opening
that opens in a second surface on the back side of the first surface, and the second substrate
coupled to the second surface of the first substrate, and at least the element in a plan view from
the thickness direction of the first substrate The present invention relates to an ultrasonic device
unit including a second substrate having a through hole continuous with the opening and having
a spread that accommodates the contour of an array.
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[0007]
The thin film ultrasonic transducer element ultrasonically vibrates the vibrating film when
transmitting ultrasonic waves.
The ultrasonic wave is transmitted from the vibrating film to the front side and emitted from the
first surface of the first substrate.
At this time, the ultrasonic waves are similarly transmitted from the vibrating membrane to the
back side. Ultrasonic waves travel within the opening. Since the opening is continuous with the
through hole, the length of the propagation path of the ultrasonic wave is increased. The
ultrasound attenuates as the length of the propagation path increases. Thus, the influence of the
ultrasonic wave transmitted from the vibrating membrane to the back side is suppressed.
[0008]
(2) In the ultrasonic device unit, the second substrate may be a wiring board. A wiring pattern is
formed of a conductive material on the wiring board. The arrangement of the conductive material
is avoided in the through hole which is continuous from the opening. Thus, the reflection of the
ultrasonic wave based on the conductive material is prevented. The influence of miscellaneous
signals is suppressed.
[0009]
(3) In the ultrasonic device unit, the second substrate may be a reinforcing plate joined to the
second surface of the first substrate. The reinforcing plate is stacked on the second surface of the
first substrate. The reinforcing plate reinforces the rigidity of the first substrate. Here, the second
substrate may be bonded to the first substrate with an adhesive for bonding.
[0010]
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(4) The space of the opening and the through hole may be filled with a material that causes
attenuation to ultrasonic waves to a greater degree than in air. The attenuation of the ultrasound
is facilitated by the material filling the openings and the through holes. As a result, the influence
of the ultrasonic wave transmitted from the vibrating membrane to the back side is reliably
prevented. If the degree of attenuation increases in this way, it can contribute to shortening the
propagation path of ultrasonic waves, in other words, thinning of the second substrate.
[0011]
(5) The thickness of the material from the thin film type ultrasonic transducer element may be an
odd multiple of one fourth of the wavelength of ultrasonic waves. According to such a structure,
even if the ultrasonic wave transmitted from the vibrating membrane to the back side is reflected
at the interface of the material, the ultrasonic wave returning to the thin film type ultrasonic
transducer element is canceled out by the ultrasonic wave from the vibrating membrane. Thus,
the influence of the ultrasonic waves transmitted from the vibrating membrane to the back side
is more effectively suppressed.
[0012]
(6) The ultrasonic device unit is separated from the thin film ultrasonic transducer element by
the air layer in the opening and in contact with the thin film ultrasonic transducer element in the
opening, and blocks at least the through hole, It may further comprise a material layer that
causes attenuation to a greater degree than in air relative to ultrasound. The attenuation of
ultrasonic waves is promoted by the material layer that blocks the through hole. As a result, the
influence of the ultrasonic wave transmitted from the vibrating membrane to the back side is
reliably prevented. If the degree of attenuation increases in this way, it can contribute to
shortening the propagation path of ultrasonic waves, in other words, thinning of the second
substrate.
[0013]
(7) The thickness of the air layer from the thin film ultrasonic transducer element may be an odd
multiple of one fourth of the wavelength of the ultrasonic wave. According to such a structure,
even if the ultrasonic wave transmitted from the vibrating membrane to the back side is reflected
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at the interface between the air layer and the material layer, the ultrasonic wave returning to the
thin film ultrasonic transducer element cancels out by the ultrasonic wave from the vibrating
membrane. Thus, the influence of the ultrasonic waves transmitted from the vibrating membrane
to the back side is more effectively suppressed.
[0014]
(8) The thickness of the material layer from the air layer may be an odd multiple of one quarter
of the wavelength of ultrasonic waves. According to such a structure, even if the ultrasonic wave
propagating in the material layer is reflected at the interface of the material layer, the ultrasonic
wave returning to the thin film type ultrasonic transducer element is canceled out by the
ultrasonic wave from the vibrating film. Thus, the influence of the ultrasonic waves transmitted
from the vibrating membrane to the back side is more effectively suppressed.
[0015]
(9) The ultrasound device unit may be incorporated into a probe for use. At this time, the probe
may include an ultrasonic device unit and a housing for supporting the ultrasonic device unit.
[0016]
(10) The ultrasonic device unit may be incorporated into an electronic device and used. At this
time, the electronic device may include an ultrasound device unit, and a processing unit
connected to the ultrasound device unit and processing an output of the ultrasound device unit.
[0017]
(11) The ultrasound device unit may be incorporated into an ultrasound imaging apparatus and
used. At this time, the ultrasound imaging apparatus is connected to an ultrasound device unit,
the ultrasound device unit, a processing unit that processes an output of the ultrasound device
unit, and generates an image, and a display that displays the image And an apparatus.
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[0018]
FIG. 1 is an external view schematically showing an ultrasonic diagnostic apparatus according to
a specific example of an electronic device according to an embodiment. It is an enlarged plan
view of the ultrasonic device concerning one embodiment. It is sectional drawing of the
ultrasonic device unit which concerns on 1st Embodiment along the AA of FIG. It is a
manufacturing method of an ultrasonic device, and is a perpendicular sectional view showing the
material with which an opening and a penetration are filled. It is an expanded fragmentary
sectional view of the ultrasonic device unit concerning a 2nd embodiment. It is a vertical
sectional view of the ultrasonic device unit concerning a 3rd embodiment. It is a vertical sectional
view of the ultrasonic device unit concerning a 4th embodiment.
[0019]
Hereinafter, an embodiment of the present invention will be described with reference to the
attached drawings. Note that the present embodiment described below does not unduly limit the
contents of the present invention described in the claims, and all of the configurations described
in the present embodiment are essential as means for solving the present invention. Not
necessarily.
[0020]
(1) Overall Configuration of Ultrasonic Diagnostic Apparatus FIG. 1 schematically shows a
specific example of an electronic apparatus according to an embodiment of the present invention,
that is, a configuration of an ultrasonic diagnostic apparatus (ultrasonic imaging apparatus) 11.
The ultrasonic diagnostic apparatus 11 includes an apparatus terminal (processing unit) 12 and
an ultrasonic probe (probe) 13. The device terminal 12 and the ultrasonic probe 13 are
connected to each other by a cable 14. The device terminal 12 and the ultrasonic probe 13
exchange electrical signals through the cable 14. A display panel (display device) 15 is
incorporated in the device terminal 12. The screen of the display panel 15 is exposed on the
surface of the device terminal 12. At the device terminal 12, an image is generated based on the
ultrasonic waves detected by the ultrasonic probe 13. The imaged detection result is displayed on
the screen of the display panel 15.
[0021]
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The ultrasonic probe 13 has a housing 16. The ultrasonic device unit DV is accommodated in the
housing 16. The ultrasound device unit DV includes an ultrasound device 17. The ultrasound
device 17 comprises an acoustic lens 18. The outer surface of the acoustic lens 18 is formed by a
partial cylindrical surface 18a. The acoustic lens 18 is formed of, for example, a silicone resin.
The acoustic lens 18 has an acoustic impedance close to that of the living body. A window hole
19 is defined in the housing 16. An acoustic lens 18 is disposed in the window hole 19. The outer
surface of the acoustic lens 18 is exposed on the surface of the housing 16. The ultrasonic device
17 outputs an ultrasonic wave from the surface and receives a reflected wave of the ultrasonic
wave.
[0022]
FIG. 2 schematically shows a plan view of the ultrasound device 17. The ultrasound device 17
comprises a base 21. An element array 22 is formed on the surface (first surface) of the base 21.
The element array 22 comprises an array of thin film ultrasonic transducer elements (hereinafter
referred to as "elements") 23 arranged in an array. The array is formed of a matrix of rows and
columns. Alternatively, a staggered arrangement may be established in the arrangement. In the
case of the staggered arrangement, the elements 23 in the even columns may be shifted by half
the row pitch with respect to the elements 23 in the odd columns. The number of elements in
one of the odd and even columns may be one less than the number of elements in the other.
[0023]
Each element 23 comprises a vibrating membrane 24. In FIG. 2, the outline of the vibrating film
24 is drawn by a dotted line in a plan view in a direction orthogonal to the film surface of the
vibrating film 24 (a plan view from the thickness direction of the substrate). The piezoelectric
element 25 is formed on the vibrating film 24. The piezoelectric element 25 is composed of an
upper electrode 26, a lower electrode 27 and a piezoelectric film 28. The piezoelectric film 28 is
sandwiched between the upper electrode 26 and the lower electrode 27 for each of the elements
23. These are stacked in the order of the lower electrode 27, the piezoelectric film 28 and the
upper electrode 26. The ultrasonic device 17 is configured as a single ultrasonic transducer
element chip (substrate).
[0024]
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A plurality of first conductors 29 are formed on the surface of the base 21. The first conductors
29 extend parallel to each other in the row direction of the array. One first conductor 29 is
assigned to each row of elements 23. One first conductor 29 is commonly connected to the
piezoelectric films 28 of the elements 23 aligned in the row direction of the array. The first
conductor 29 forms an upper electrode 26 for each element 23. Both ends of the first conductor
29 are respectively connected to the pair of lead wirings 31. The lead wires 31 extend parallel to
each other in the column direction of the array. Therefore, all the first conductors 29 have the
same length. Thus, the upper electrode 26 is connected in common to the elements 23 of the
entire matrix. The first conductor 29 can be made of, for example, iridium (Ir). However, other
conductive materials may be used for the first conductor 29.
[0025]
A plurality of second conductors 32 are formed on the surface of the base 21. The second
conductors 32 extend parallel to each other in the column direction of the array. One second
conductor 32 is assigned to each row of elements 23. One second conductor 32 is disposed in
common to the piezoelectric films 28 of the elements 23 arranged in the column direction of the
array. The second conductor 32 forms the lower electrode 27 for each element 23. For example,
a laminated film of titanium (Ti), iridium (Ir), platinum (Pt) and titanium (Ti) can be used for the
second conductor 32. However, other conductive materials may be used for the second
conductor 32.
[0026]
The energization of the elements 23 is switched for each row. Linear scan and sector scan are
realized according to such switching of energization. Since the elements 23 in one column
simultaneously output ultrasonic waves, the number of one columns, that is, the number of rows
in the array can be determined according to the output level of the ultrasonic waves. The number
of rows may be set to, for example, about 10 to 15 rows. Five lines are drawn, omitted in the
figure. The number of columns of the array can be determined according to the spread of the
scan range. The number of columns may be set to 128 or 256, for example. It is omitted in the
figure and eight columns are drawn. The roles of the upper electrode 26 and the lower electrode
27 may be switched. That is, while the lower electrode is commonly connected to the elements
23 of the entire matrix, the upper electrode may be commonly connected to the elements 23 in
each array column.
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[0027]
The outline of the base 21 has a first side 21 a and a second side 21 b opposed to each other by
a pair of straight lines parallel to each other. The first terminal array 33a of one line is disposed
between the first side 21a and the contour of the element array 22. The second terminal array
33 b of one line is disposed between the second side 21 b and the contour of the element array
22. The first terminal array 33a can form one line parallel to the first side 21a. The second
terminal array 33 b can form one line parallel to the second side 21 b. The first terminal array 33
a includes a pair of upper electrode terminals 34 and a plurality of lower electrode terminals 35.
Similarly, the second terminal array 33 b includes a pair of upper electrode terminals 36 and a
plurality of lower electrode terminals 37. The upper electrode terminals 34 and 36 are connected
to both ends of one lead wiring 31 respectively. The lead wire 31 and the upper electrode
terminals 34 and 36 may be formed plane-symmetrically in the vertical plane which bisects the
element array 22. Lower electrode terminals 35 and 37 are connected to both ends of one
second conductor 32, respectively. The second conductor 32 and the lower electrode terminals
35 and 37 may be formed plane-symmetrically in a vertical plane which bisects the element
array 22. Here, the outline of the base 21 is formed in a rectangular shape. The contour of the
base 21 may be square or trapezoidal.
[0028]
A first flexible printed wiring board (hereinafter referred to as “first wiring board”) 38 is
connected to the base 21. The first wiring board 38 covers the first terminal array 33a. At one
end of the first wiring board 38, conductive lines, that is, first signal lines 39 are formed
corresponding to the upper electrode terminal 34 and the lower electrode terminal 35
respectively. The first signal line 39 is individually directed to the upper electrode terminal 34
and the lower electrode terminal 35 and joined separately. Similarly, a second flexible printed
wiring board (hereinafter referred to as a “second wiring board”) 41 covers the base 21. The
second wiring board 41 covers the second terminal array 33 b. At one end of the second wiring
board 41, a conductive line, that is, a second signal line 42 is formed corresponding to the upper
electrode terminal 36 and the lower electrode terminal 37 individually. The second signal lines
42 are individually directed to the upper electrode terminal 36 and the lower electrode terminal
37 and joined separately.
[0029]
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(2) Configuration of Ultrasonic Device Unit According to First Embodiment As shown in FIG. 3,
the base 21 includes a substrate (first substrate) 44 and a covering film 45. A covering film 45 is
formed on one surface of the substrate 44. An opening 46 is formed in the substrate 44 for each
element 23. The openings 46 are arranged in an array relative to the substrate 44. The individual
openings 46 open to the back surface (second surface) for each element 23. The outline of the
area in which the opening 46 is disposed corresponds to the outline of the element array 22. A
partition wall 47 is partitioned between two adjacent openings 46. Adjacent openings 46 are
separated by a partition wall 47. The wall thickness of the partition wall 47 corresponds to the
distance between the openings 46. The partition wall 47 defines two wall surfaces in a plane
extending parallel to one another. The wall thickness corresponds to the distance between the
two wall surfaces. That is, the wall thickness can be defined by the length of a perpendicular line
between the wall surfaces orthogonal to the wall surfaces. The substrate 44 may be formed of,
for example, a silicon substrate.
[0030]
The covering film 45 is composed of a silicon oxide (SiO 2) layer 48 stacked on the surface of the
substrate 44 and a zirconium oxide (ZrO 2) layer 49 stacked on the surface of the silicon oxide
layer 48. The covering film 45 is in contact with the opening 46. Thus, a part of the covering film
45 forms the vibrating film 24 corresponding to the contour of the opening 46. The vibrating
film 24 is a portion of the coating film 45 that can vibrate in the thickness direction of the
substrate 44 since it faces the opening 46. The film thickness of the silicon oxide layer 48 can be
determined based on the resonant frequency.
[0031]
The lower electrode 27, the piezoelectric film 28 and the upper electrode 26 are sequentially
stacked on the surface of the vibrating film 24. The piezoelectric film 28 can be formed of, for
example, lead zirconate titanate (PZT). Other piezoelectric materials may be used for the
piezoelectric film 28. Here, the piezoelectric film 28 completely covers the second conductor 32
under the first conductor 29. A short circuit can be avoided between the first conductor 29 and
the second conductor 32 by the action of the piezoelectric film 28.
[0032]
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An acoustic matching layer 51 is stacked on the surface of the base 21. The acoustic matching
layer 51 covers the element array 22. The film thickness of the acoustic matching layer 51 is
determined in accordance with the resonant frequency of the vibrating film 24. For example, a
silicone resin film can be used for the acoustic matching layer 51. An acoustic lens 18 is disposed
on the acoustic matching layer 51. The acoustic lens 18 is in close contact with the surface of the
acoustic matching layer 51 in the plane behind the partial cylindrical surface 18 a. The acoustic
lens 18 is bonded to the base 21 by the action of the acoustic matching layer 51. The generatrix
of the partial cylindrical surface 18 a is positioned parallel to the first conductor 29. The
curvature of the partial cylindrical surface 18a is determined in accordance with the focal
position of the ultrasonic wave transmitted from the row of elements 23 connected to the second
conductor 33 in one stripe.
[0033]
A reinforcing plate (second substrate) 53 as a backing material is bonded to the back surface of
the base 21. The reinforcing plate 53 is formed in a flat plate shape. The back surface of the base
21 is superimposed on the front surface of the reinforcing plate 53. Through holes 54 are
formed in the reinforcing plate 53. The surface of the reinforcing plate 53 is bonded to the back
surface of the base 21. In such bonding, the reinforcing plate 53 may be bonded to the base 21
with an adhesive. The reinforcing plate 53 reinforces the rigidity of the base 21. By the action of
the reinforcing plate 53, the flatness is well maintained on the surface of the base 21. The
reinforcing plate 53 can comprise, for example, a rigid base material. Such base material may be
formed of a metal material such as, for example, 42 alloy (iron-nickel alloy).
[0034]
The through hole 54 has a width that accommodates at least the contour of the element array 22
in a plan view from the thickness direction of the base 21. The through hole 54 is continuous
with the opening 46 of the element 23 included in the element array 22. Here, the openings 46
and the through holes 54 are filled with air. The thickness of air from the vibrating film 24 is set
to an odd multiple of one fourth (λ / 4) of the wavelength λ of the ultrasonic wave. The
thickness of such air can be set based on the thickness of the substrate 44 and the reinforcing
plate 53.
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[0035]
The ultrasound device unit DV includes a wiring board 56. The wiring substrate 56 is coupled to
the ultrasonic device 17. The back surface of the reinforcing plate 53 is superimposed on the
front surface of the wiring board 56. The ultrasonic device 17 may be fixed to the wiring
substrate 56 with a resin material. Wiring patterns 57 are formed on the wiring board 56. The
first wiring board 38 and the second wiring board 41 of the ultrasonic device 17 are connected
to the wiring pattern 57. The wiring pattern 57 includes a first conductive pad 58a and a second
conductive pad 58b. The first conductive pad 58 a and the second conductive pad 58 b are
formed on the surface of the wiring substrate 56. The respective first conductive pads 58 a and
the second conductive pads 58 b are arranged corresponding to the respective first signal lines
39 and the second signal lines 42. The first conductive pad 58a and the second conductive pad
58b may be made of a conductive material such as copper, for example. Corresponding first
signal lines 39 and second signal lines 42 are bonded to the respective first conductive pads 58a
and second conductive pads 58b.
[0036]
The first connector 59 a and the second connector 59 b are disposed on the back surface of the
wiring board 56. The first connector 59a is connected to the first conductive pad 58a by the via
61a. The second connector 59b is connected to the second conductive pad 58b by the via 61b.
The vias 61 a and 61 b penetrate from the front surface to the back surface of the wiring board
56. The cable 14 is formed by the wires 62a and 62b connected to the first connector 59a and
the second connector 59b, respectively.
[0037]
(3) Operation of Ultrasonic Diagnostic Apparatus Next, the operation of the ultrasonic diagnostic
apparatus 11 will be briefly described. A pulse signal is supplied to the piezoelectric element 25
when transmitting ultrasonic waves. The pulse signal is supplied to the elements 23 row by row
through the lower electrode terminals 35 and 37 and the upper electrode terminals 34 and 36.
In each element 23, an electric field acts on the piezoelectric film 28 between the lower electrode
27 and the upper electrode 26. The piezoelectric film 28 vibrates at the frequency of ultrasonic
waves. The vibration of the piezoelectric film 28 is transmitted to the vibrating film 24. Thus, the
vibrating film 24 vibrates ultrasonically. As a result, the desired ultrasound beam is emitted
towards the object (e.g. inside the human body).
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[0038]
The reflected wave of the ultrasonic wave vibrates the vibrating film 24. The ultrasonic vibration
of the vibrating film 24 ultrasonically vibrates the piezoelectric film 28 at a desired frequency. A
voltage is output from the piezoelectric element 25 in accordance with the piezoelectric effect of
the piezoelectric element 25. In each element 23, a potential is generated between the upper
electrode 26 and the lower electrode 27. The potential is output as an electrical signal from the
lower electrode terminals 35, 37 and the upper electrode terminals 34, 36. The ultrasound is
thus detected.
[0039]
Transmission and reception of ultrasound waves are repeated. As a result, linear scan and sector
scan are realized. When the scan is complete, an image is formed based on the digital signal of
the output signal. The formed image is displayed on the screen of the display panel 15.
[0040]
As described above, the vibrating film 24 vibrates ultrasonically when transmitting ultrasonic
waves. The ultrasonic waves are transmitted from the vibrating film 24 to the front side and
emitted from the surface of the substrate 44. At this time, the ultrasonic waves are similarly
transmitted from the vibrating film 24 to the back side. The ultrasonic waves travel the air in the
opening 46. Since the opening 46 is continuous with the through hole 54, the length of the
ultrasonic wave propagation path is increased. The ultrasound attenuates as the length of the
propagation path increases. Thus, the influence of the ultrasonic waves transmitted from the
vibrating film 24 to the back side is suppressed.
[0041]
The openings 46 and the through holes 54 may be filled with a specific material. The material is
desired to cause attenuation to ultrasound to a greater extent than in air. A resin material can be
used for such a material. Attenuation of ultrasound is promoted by the action of the material. As
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a result, the influence of the ultrasonic wave transmitted from the vibrating film 24 to the back
side is reliably prevented. Thus, if the degree of attenuation increases, it can contribute to
shortening of the propagation path of ultrasonic waves, in other words, thinning of the
reinforcing plate 53. For filling the material, for example, as shown in FIG. 4, after the reinforcing
plate 53 is attached, the flowable material 63 may be poured into the through hole 54 and the
opening 46. When the poured material 63 hardens, the openings 46 and the through holes 54
can be filled with the material 63. Material 63 can function as an adhesive if wiring substrate 56
is stacked prior to curing. Moreover, remaining of air (bubbles) in the through hole 54 can be
avoided.
[0042]
The thickness t1 of the material from the vibrating film 24 may be set to an odd multiple of one
fourth (λ / 4) of the wavelength λ of the ultrasonic wave. The thickness of such a material can
be set based on the thickness of the substrate 44 and the reinforcing plate 53. According to such
a structure, even if the ultrasonic wave transmitted from the vibrating membrane 24 to the back
side is reflected at the interface of the material 63, the ultrasonic wave returning to the element
23 is canceled by the ultrasonic wave from the vibrating membrane 24. Thus, the influence of
the ultrasonic wave transmitted from the vibrating film 24 to the back side is more effectively
suppressed.
[0043]
(4) Ultrasonic Device Unit According to Second Embodiment As shown in FIG. 5, in the ultrasonic
device 17, an air layer 65 in contact with the vibrating film 24 may be formed in the opening 46.
At this time, the through hole 54 may be closed by the material layer 66. Material layer 66 is
separated from vibrating membrane 24 by air layer 65. The material layer 66 is desirably formed
of a material that causes attenuation to ultrasound to a greater extent than in air. A resin material
can be used for such a material. The action of the material layer 66 promotes the attenuation of
ultrasonic waves. As a result, the influence of the ultrasonic wave transmitted from the vibrating
film 24 to the back side is reliably prevented. Thus, if the degree of attenuation increases, it can
contribute to shortening of the propagation path of ultrasonic waves, in other words, thinning of
the reinforcing plate 53. The material layer 66 may be formed in the through hole 54 of the
reinforcing plate 53 prior to the bonding of the reinforcing plate 53 to the substrate 44.
[0044]
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The thickness t2 of the air layer 65 from the vibrating film 24 may be set to an odd multiple of
one fourth (λ / 4) of the wavelength λ of the ultrasonic wave. According to such a structure,
even if the ultrasonic wave transmitted from the vibrating membrane 24 to the back side is
reflected at the interface between the air layer 65 and the material layer 66, the ultrasonic wave
returning toward the element 23 cancels out by the ultrasonic wave from the vibrating
membrane 24 . Thus, the influence of the ultrasonic wave transmitted from the vibrating film 24
to the back side is more effectively suppressed.
[0045]
Similarly, the thickness t3 of the material layer 66 from the air layer 65 may be set to an odd
multiple of one fourth (λ / 4) of the wavelength λ of the ultrasonic wave. According to such a
structure, even if the ultrasonic wave propagating in the material layer 66 is reflected at the
interface of the material layer 66, the ultrasonic wave returning toward the element 23 is
canceled out by the ultrasonic wave from the vibrating film 24. Thus, the influence of the
ultrasonic wave transmitted from the vibrating film 24 to the back side is more effectively
suppressed. Besides, the material layer 66 may enter the opening 46 depending on the thickness
of the air layer 65.
[0046]
(5) Ultrasonic Device Unit According to Third Embodiment FIG. 6 schematically shows a
configuration of an ultrasonic device unit DVa according to a third embodiment. In the ultrasonic
device unit DVa, a through hole 68 is formed in the wiring board 67 in addition to the through
hole 54 of the reinforcing plate 53. The through hole 68 has a width that accommodates at least
the contour of the element array 22 in a plan view from the thickness direction of the wiring
board 67. The through hole 68 is continuous with the through hole 54 of the reinforcing plate
53. The through holes 68, 54 may be filled with air and may be filled with a material that causes
attenuation to a greater degree than ultrasound in ultrasound. Since the opening 46 is
continuous with the through holes 54, 68, the length of the ultrasonic wave propagation path is
increased. The ultrasound attenuates as the length of the propagation path increases. Thus, the
influence of the ultrasonic waves transmitted from the vibrating film 24 to the back side is
suppressed. When filled with the material, the attenuation of ultrasonic waves is promoted by the
material filling the through holes 54, 68. As described above, the thickness of the material from
the vibrating film 24 may be set to an odd multiple of one fourth (λ / 4) of the wavelength λ of
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the ultrasonic wave. According to such a structure, even if the ultrasonic wave transmitted from
the vibrating membrane 24 to the back side is reflected at the interface of the material, the
ultrasonic wave returning to the element 23 is canceled out by the ultrasonic wave from the
vibrating membrane 24. Thus, the influence of the ultrasonic wave transmitted from the vibrating
film 24 to the back side is more effectively suppressed.
[0047]
As described above, an air layer in contact with the vibrating membrane 24 may be formed in the
opening 46 and the through holes 54, 68. The through hole 68 may be closed by a layer of
material separated from the vibrating membrane 24 by an air layer. The thickness of the air layer
from the vibrating film 24 may be set to an odd multiple of one fourth (λ / 4) of the wavelength
λ of the ultrasonic wave. The thickness of the material layer from the air layer may be set to an
odd multiple of one fourth (λ / 4) of the wavelength λ of the ultrasonic wave. Depending on the
thickness of the air layer, the material layer may enter the through hole 54 or may reach the
opening 46. The other configuration is the same as that of the above-described ultrasonic device
unit DV.
[0048]
(6) Ultrasonic Device Unit According to Fourth Embodiment FIG. 7 schematically shows a
configuration of an ultrasonic device unit DVb according to a fourth embodiment. In the
ultrasonic device unit DVb, the base 21 is directly received by the wiring board (wiring board)
67. In other words, the reinforcing plate 53 is omitted when the ultrasonic device 17 and the
wiring board 67 are joined. As described above, the through hole 68 is formed in the wiring
board 67. The through hole 68 continues from the opening 46. The other configuration is the
same as that of the above-described ultrasound device units DV and DVa.
[0049]
It should be understood by those skilled in the art that although the present embodiment has
been described in detail as described above, many modifications can be made without departing
substantially from the novel matters and effects of the present invention. Therefore, all such
modifications are included in the scope of the present invention. For example, in the specification
or the drawings, the terms described together with the broader or synonymous different terms at
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least once can be replaced with the different terms anywhere in the specification or the drawings.
In addition, the ultrasonic diagnostic apparatus 11, the apparatus terminal 12, the ultrasonic
probe 13, the display panel 15, the housing 16, the base 21, the element 23, the first and second
wiring boards 38 and 41, the acoustic matching layer 51, the acoustic lens 52 The configuration
and operation of the present invention are not limited to those described in the present
embodiment, and various modifications are possible.
[0050]
11 Ultrasonic imaging apparatus (ultrasound diagnostic apparatus) as electronic equipment, 12
processing unit (apparatus terminal), 13 probes (ultrasonic probe), 15 display apparatus (display
panel), 16 housings, 17 ultrasound devices, 22 Element array, 23 thin film type ultrasonic
transducer element, 44 first substrate (substrate), 46 opening, 53 second substrate
(reinforcement plate), 54 through hole, 65 air layer, 66 material layer, 67 wiring substrate, 68
Through hole, DV ultrasound device unit, DVa ultrasound device unit, DVb ultrasound device
unit.
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