close

Вход

Забыли?

вход по аккаунту

?

JP2014076242

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2014076242
PROBLEM TO BE SOLVED: When a light reflection layer is disposed directly above a vibrating
membrane of a capacitive transducer, a change in a spring constant of the vibrating membrane, a
variation in a deformation amount of the vibrating membrane, or the like may occur. SOLUTION:
The probe according to the present invention is a probe for receiving an acoustic wave from a
subject, and a vibrating membrane including one of a pair of electrodes formed with a gap
therebetween is the acoustic wave. An element having a cell structure vibratably supported by
the element, a light reflecting layer provided closer to the object than the element and reflecting
light, provided between the element and the light reflecting layer, the light reflecting And a
support layer for supporting the layer, wherein the support layer has a breaking stress of 50
MPa or more. [Selected figure] Figure 1
Probe, object information acquiring apparatus, and method of manufacturing probe
[0001]
The present invention relates to a probe, an object information acquiring apparatus, and a
method of manufacturing a probe. In particular, the present invention relates to a probe that
receives an acoustic wave generated from a subject due to light irradiated to the subject, a
subject information acquiring apparatus including the probe, and a method of manufacturing the
probe.
[0002]
04-05-2019
1
One of the optical imaging techniques is a photoacoustic imaging technique called Photoacoustic
Tomography (PAT: Photoacoustic Tomography). Photoacoustic imaging is a technology for
detecting an acoustic wave (also referred to as “photoacoustic wave”) generated by light
irradiation and generating image data from the obtained reception signal. The photoacoustic
wave is generated by the pulse light from the light source being applied to the subject, and the
tissue that has absorbed the energy of the light propagated in the subject vibrates. The
wavelength of this acoustic wave depends on the size of the tissue and is typically in the
wavelength range of ultrasonic waves.
[0003]
Patent Document 1 proposes a probe including an element for receiving such an acoustic wave.
In photoacoustic imaging, when light for generating an acoustic wave is incident on the receiving
surface of an element in a probe, an acoustic wave is generated on the receiving surface and may
become noise. In order to suppress such an acoustic wave generated on the receiving surface, the
probe of Patent Document 1 is provided with a light reflecting layer directly on the receiving
surface of the element of the probe so that light does not enter the receiving surface.
[0004]
On the other hand, research on CMUT (Capacitive Micromachined Ultrasonic Transducer)
manufactured using a micromachining technology is being made as a substitute of a piezoelectric
element. CMUT is a transducer equipped with a capacitive element, and can transmit and receive
acoustic waves such as ultrasonic waves using the vibration of the vibrating film, and in
particular can obtain excellent broadband characteristics in liquid it can.
[0005]
JP, 2010-075681, A
[0006]
Also in a capacitive transducer, when light irradiated to generate an acoustic wave is incident on
the receiving surface of the element, an acoustic wave is generated, which may result in noise.
04-05-2019
2
However, as in Patent Document 1, when the light reflection layer is disposed immediately above
the element, the stress of the light reflection layer causes a change in the spring constant of the
vibrating film that constitutes the element and a variation in the deformation of the vibrating
film. there is a possibility. Such an influence on the vibrating film may cause a decrease in the
sensitivity of the element, variation, and a decrease in bandwidth.
[0007]
An object of the present invention is to provide a light reflection layer while suppressing the
influence on an element in view of the above-mentioned problems.
[0008]
The probe according to the present invention is a probe for receiving an acoustic wave from a
subject, and a vibrating membrane including one of a pair of electrodes formed with a gap
therebetween can be vibrated by the acoustic wave. An element having a supported cell
structure, a light reflecting layer provided on the object side of the element and reflecting light,
provided between the element and the light reflecting layer, and supporting the light reflecting
layer A support layer, and the support layer has a breaking stress of 50 MPa or more.
[0009]
In the method of manufacturing a probe according to the present invention, a vibrating
membrane including one of a pair of electrodes formed with a gap is provided with an element
having a cell structure supported so as to be vibrated by the acoustic wave. A method of
manufacturing a probe, comprising the steps of: forming a light reflecting layer on a film;
bonding the film to a housing; filling the case with an acoustic matching agent; and filling the
acoustic matching agent Heat-hardening an acoustic matching agent after inserting the substrate
provided with the element into the housing.
[0010]
According to the present invention, since the support layer is provided between the element and
the light reflection layer, even when the light reflection layer is provided, the influence on the
vibrating film of the element can be reduced.
[0011]
04-05-2019
3
It is a sectional view showing an example of composition of a probe.
It is a schematic diagram which shows an example of a structure of a capacitive transducer.
It is a transparent perspective view which shows an example of the housing | casing of a probe.
It is a schematic diagram which shows an example of a connection of a capacitive transducer and
a flexible substrate.
It is sectional drawing which shows an example of insertion to the housing | casing of a
capacitive transducer. It is a schematic diagram of a subject information acquisition device
provided with a probe.
[0012]
Hereinafter, an example of an embodiment of the present invention will be described with
reference to the drawings.
[0013]
FIG. 1 is a cross-sectional view showing an example of the configuration of a probe.
The probe of the present embodiment includes at least a capacitive transducer 33, which is an
electromechanical transducer, a support layer 10, and a light reflection layer 6. FIG. 1 shows a
preferred example of this embodiment, in which an acoustic matching layer 9 is provided
between the capacitive transducer 33 and the support layer 10. Further, the capacitive
transducer 33 is housed in a housing frame 11 as a housing, and members such as a flexible
substrate are omitted. First, the capacitive transducer 33 will be described with reference to FIG.
[0014]
04-05-2019
4
(Capacitance Transducer) FIG. 2 (a) is a top view of the capacitance transducer 33, and FIG. 2 (b)
is a cross-sectional view taken along line A-B of FIG. 2 (a). The capacitive transducer 33 has one
or more elements 1 (elements) having one or more cell structures 2. The cell structure 2 includes
a pair of electrodes formed with a gap, and shows a structure in which a vibrating film including
one of the pair of electrodes is vibratably supported. Although only four elements 1 are shown in
FIG. 2, the number of elements may be any number. Each element 1 is formed of nine cell
structures 2, but the number of cell structures 2 may be any number. The shape of the cell
structure is circular in FIG. 2, but may be square, hexagonal or the like.
[0015]
In FIG. 2B, a semiconductor substrate such as a silicon substrate is used as the substrate 3, and
the substrate 3 functions as a first electrode. However, a layer formed of metal or the like may be
provided over the substrate to be used as the first electrode. There is a gap 5 between the
substrate 3 as the first electrode and the second electrode 8. A support 4 is formed on the
substrate 3, and the second electrode 8 and the vibrating membrane 7 are vibratably supported
by the support 4.
[0016]
In FIG. 2B, the vibrating film 7 is, for example, single crystal silicon. In the case where the
vibrating film 7 is a low resistance single crystal silicon, single crystal silicon can be used as the
second electrode, and therefore, a configuration in which a metal to be the second electrode 8 is
not disposed is also possible. The vibrating film 7 may be an insulating film such as a silicon
nitride film or a silicon oxide film.
[0017]
The substrate 3 as the first electrode and the second electrode 8 face each other, and a voltage is
applied between the pair of electrodes from voltage application means (not shown). Further, the
element 1 can extract an electric signal for each element from the second electrode 8 by using
the lead-out wiring. That is, the first electrode is a common electrode electrically connected
between the elements, and the second electrode 8 is a signal extraction electrode for extracting
an electric signal of each element. However, when the first electrode is electrically separated for
each element, the second electrode 8 may be a common electrode and a signal extraction
04-05-2019
5
electrode for extracting an electric signal for each element from the first electrode.
[0018]
(Driving principle) The driving principle of the capacitive transducer of the present invention will
be described. When receiving an acoustic wave, the voltage application means applies a DC
voltage to the first electrode so that a potential difference is generated between the first
electrode and the second electrode 8. When the acoustic wave is received, the vibrating
membrane 7 on which the second electrode 8 is formed is bent, so the distance between the
second electrode 8 and the first electrode (the distance in the depth direction of the gap 5)
changes. The capacitance changes. The change in capacitance causes the second electrode 8 to
output a current. This current is converted into a voltage by a current-voltage conversion
element (not shown) to obtain an acoustic wave reception signal. As described above, a direct
current voltage may be applied to the second electrode 8 by changing the configuration of the
lead wiring, and an electrical signal may be extracted from the first electrode for each element.
[0019]
In addition, the capacitive transducer of this embodiment can also transmit an acoustic wave.
When an acoustic wave is transmitted, a direct current voltage is applied to the first electrode, an
alternating current voltage is applied to the second electrode 8, and the vibrating film 7 on which
the second electrode 8 is formed is vibrated by electrostatic force. An acoustic wave can be
transmitted by this vibration. Also in the case of transmitting the acoustic wave, the direct
current voltage may be applied to the second electrode 8 and the alternating current voltage may
be applied to the first electrode by changing the configuration of the lead wiring, and the
vibrating film 7 may be vibrated. .
[0020]
(Acoustic Matching Layer 9) As shown in FIG. 1, in the probe of the present embodiment, the
acoustic matching layer 9 is located on the vibrating membrane 7 of the capacitive transducer 33
(the object side). The acoustic impedance of the acoustic matching layer 9 is preferably close to
the acoustic impedance of the vibrating membrane 7, and specifically, the acoustic impedance is
preferably 1 M Rayls or more and 2 M Rayls or less. The acoustic matching layer 9 is preferably
a silicone rubber obtained by crosslinking an organic polymer containing polydimethylsiloxane
04-05-2019
6
(PDMS) as a main component. What added the silica particle etc. to PDMS, the fluoro silicone etc.
which substituted a part of hydrogen of PDMS with fluorine may be used. The silicone rubber has
little influence on the vibrating film 7, and its thickness is preferably 10 μm to 900 μm. The
Young's modulus of the acoustic matching layer 9 is preferably 10 MPa or less so as not to
significantly change the mechanical properties such as the amount of deformation of the
vibrating film 7 and the spring constant. In the case of the silicone rubber which bridge |
crosslinked the organic polymer which had polydimethylsiloxane (PDMS) as a main component,
Young's modulus is about 1 Mpa.
[0021]
As described above, since the acoustic matching layer 9 has a small Young's modulus, if the light
reflecting layer 6 is formed directly on the acoustic matching layer 9, the film stress may affect
the light reflecting layer 6. So, in this embodiment, the light reflection layer 6 is formed through
the support layer 10.
[0022]
(Support Layer 10) The support layer 10 preferably has a Young's modulus larger than that of
the acoustic matching layer 9 so that the light reflection layer 6 can be prevented from being
bent or deformed. Specifically, the Young's modulus of the support layer 10 is preferably 100
MPa or more and 20 GPa or less. The acoustic impedance of the support layer 10 is preferably
an acoustic impedance close to the acoustic matching layer 9, and specifically, the acoustic
impedance is preferably 1 MRayls to 5 MRayls.
[0023]
Here, as a film whose acoustic impedance is close to the acoustic matching layer 9, there is an
olefin-based film such as polymethylpentene or polyethylene. However, such olefin-based films
tend to be easily split when scratched or the like, and may be difficult to handle in terms of
handling.
[0024]
04-05-2019
7
Therefore, it is preferable that the support layer 10 of the light reflection layer 6 not only has
little acoustic wave reflection at the interface with the acoustic matching layer 9 but also have
sufficient rigidity (in particular, sufficient breaking stress). Specifically, in the support layer 10 of
the present embodiment, the breaking stress is 50 MPa or more. By having such a breaking
stress, the support layer 10 becomes difficult to tear. Furthermore, as described above, it is
preferable that not only the breaking stress is large but also the Young's modulus is large.
Specifically, the Young's modulus is preferably 100 MPa or more and 20 GPa or less.
[0025]
In addition, when the probe is used in contact with a specific acoustic medium (acoustic matching
liquid), the solubility parameter (Solubility Parameter: SP value) of the support layer 10 is
separated by 5 or more with respect to the solubility parameter of the acoustic medium Is
preferred. That is, the difference between the solubility parameter of the support layer 10 and
the solubility parameter of the acoustic medium is preferably 5 or more. Solubility parameter is a
solubility indicator that indicates how soluble a substance is in a substance. This is because when
the acoustic medium infiltrates from a flaw or the like attached to the light reflection layer 6 and
contacts the support layer 10, it is considered as one factor that the support layer 10 breaks.
When the solubility parameter of the support layer 10 is 5 or more away from the solubility
parameter of the acoustic medium, the resistance to the acoustic medium is increased.
[0026]
Suitable materials for the support layer 10 disposed on the acoustic matching layer 9 include
polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyimides,
polycarbonates, nylons, and polyether sulfones. In particular, polyester is preferred as a
preferred material. The polyester film has a breaking stress of more than 80 MPa, a Young's
modulus of more than 1 GPa, and sufficient rigidity (in particular, breaking stress). Moreover, the
polyester film is excellent in surface smoothness, and is excellent as a support base of the light
reflection layer 6. Here, while polyester is high in rigidity, acoustic impedance also increases.
However, by setting the polyester film to a desired thickness or less (details will be described
later), it is possible to suppress a decrease in the transmittance of acoustic waves. In addition,
when castor oil is used as the acoustic medium, the solubility parameter of castor oil is 16.2, and
the solubility parameter of polyester film is 10.7, so it has sufficient resistance to castor oil. The
thickness of the polyester film and the decrease in the transmissivity of the photoacoustic wave
will be described below.
04-05-2019
8
[0027]
The acoustic impedance of the polyester film is 2.9 Mrayls. The intensity of the acoustic wave
decreases when it reaches the vibrating film 7 due to reflection or the like at the interface
between the acoustic matching layer 9 and the support layer 10 made of polyester film. At this
time, the intensity of the acoustic wave transmitted to the vibrating film 7 depends on the
thickness of the polyester film. The velocity of sound (propagation velocity of acoustic waves) in
the polyester film is 2260 m / s.
[0028]
When the probe is in the liquid of the acoustic medium, the acoustic impedance of the liquid of
the acoustic medium is 1.3 Mrayls. As the acoustic medium, for example, castor oil, olive oil,
glycerin, glycol ether, etc., or a mixture thereof is used. When PDMS is used as the acoustic
matching layer 9, the acoustic impedance of the PDMS is 1.5 Mrayls, and the speed of sound is
1000 m / s. The mechanical impedance of the vibrating membrane 7 depends on the frequency
(the frequency of the vibrating membrane), but in most cases is equal to or less than that of the
acoustic medium.
[0029]
Under such conditions, when the thickness of the polyester film is 30 μm or less, the decrease in
the acoustic wave transmittance when there is a polyester film is 1 MHz or more to 5 MHz,
compared to the case where there is no polyester film as the support layer 10 The frequency
range is 10% or less in the following frequency range, and 15% or less in the frequency range of
1 MHz to 8 MHz.
[0030]
On the other hand, when the polyester film is thickened to 40 μm, the decrease in the acoustic
wave transmittance when there is a polyester film is 13% and 1 MHz to 8 MHz in the frequency
range of 1 MHz to 5 MHz, compared to when there is no polyester film. Will be 19%.
04-05-2019
9
Therefore, it can be seen that the transmission rate of the acoustic wave decreases as the
thickness of the polyester film is increased. Therefore, in this embodiment, when using a
polyester film as the support layer 10, it is preferable to make thickness into 30 micrometers or
less.
[0031]
(Light Reflection Layer 6) The light reflection layer 6 of the present embodiment is a member for
suppressing the incidence of light on the element 1. Specifically, it is a member for reflecting the
irradiation light to the subject or the scattered light thereof. When diagnosing a living body such
as a breast as a subject, a near infrared region with a wavelength of 700 nm or more and 1000
nm or less is often used as laser light. The light reflecting layer 6 preferably has a high
reflectance (preferably 80% or more, more preferably 90% or more) to light (for example, 700 to
1000 nm) in a wavelength range to be used. Specifically, the light reflecting layer 6 is preferably
made of a metal thin film, and a metal containing at least one element of Au, Ag, Al, and Cu, or an
alloy thereof can be used.
[0032]
Moreover, it is preferable that the film thickness of the light reflection layer 6 is 150 nm or more.
If it is 150 nm or more, sufficient reflectance can be obtained. However, in consideration of
acoustic impedance, it is preferably 10 μm or less. For example, in the case of Au, since the
acoustic impedance is as high as about 63 × 10 <6> [kg · m <-2> · s <-1>], in order to prevent
reflection of the acoustic wave due to acoustic impedance mismatch, make it thin to some extent
There is a need. Therefore, in the case of Au, the film thickness is preferably 1/30 or less of the
wavelength of the acoustic wave in the material. In particular, the thickness of the Au film is 5
μm or less, considering that the reception band of the acoustic wave generated by the
photoacoustic effect is usually about 10 MHz and the wavelength in water at 10 MHz is about
150 μm. Is preferred. Vapor deposition or sputtering can be used as a formation method.
Further, in order to increase the adhesion, an underlayer of Cr or Ti may be provided.
[0033]
Moreover, as the light reflection layer 6, not only a metal film but also a dielectric multilayer film
can be used. Furthermore, a laminated structure in which a dielectric multilayer film is formed on
04-05-2019
10
a metal film can also be used. Such a laminated structure is preferable because the reflectance
can be further improved.
[0034]
(Arrangement of Support Layer 10 in Case) FIG. 3 is a schematic view showing a tip portion of a
case frame 11 which is a case for housing a capacitive transducer inside. The casing frame 11 of
the probe is often formed of metal or alloy, and aluminum, SUS, etc. may be mentioned, but other
materials such as ceramics may be used. The light reflecting layer 6 is preferably disposed flat on
the surface of the probe on the side of the subject (the side facing the subject). If the flatness of
the light reflection layer 6 is impaired, the thickness of the acoustic matching layer 9 disposed
between the surface of the element and the light reflection layer 6 becomes nonuniform, so the
interface reflection condition of the photoacoustic wave Is not uniform, which may cause
interference with received acoustic waves such as interference of multiple reflections and a
decrease in reception intensity. For this reason, it is preferable to arrange in the housing without
damaging the flatness of the light reflection layer 6.
[0035]
It is conceivable to form the light reflection layer 6 in advance on a film to be the support layer
10. Then, after applying an adhesive to the upper end surface 12 of the housing frame 11, the
support layer 10 having the light reflection layer 6 formed on the upper end surface 12 is
disposed, and the pressure of the support layer 10 is increased. The support layer 10 is adhered
to the upper end surface 12 by curing. Therefore, the heat shrinkage of the support layer 10
such as a polyester film is preferably 1.2% or more. The polyester film or the like used as the
support layer 10 is stretched in its manufacturing process, and the heat shrinkage property
changes mainly depending on the stretching conditions. The heat shrinkage is the shrinkage
when the film is held at a certain temperature and then returned to room temperature.
[0036]
Here, Table 1 shows the results of actually preparing polyester films having different heat
shrinkage rates and adhering them to the upper end face 12.
[0037]
04-05-2019
11
[0038]
The heat shrinkage rate was a value obtained when the temperature was returned to room
temperature (20 ° C.) after being placed at a temperature of 150 ° C. for 30 minutes.
The frame 11 used was a frame made of aluminum.
The result of flatness after bonding shows the result evaluated by visual observation. The
bonding temperature is 120 ° C. As shown in the results of the polyester film of Table 1, when
the film used as the support layer 10 is fixed to the housing frame 11 with an adhesive, the
difference between the thermal expansion coefficients of the housing frame 11 and the film is
the shrinkage of the film. It is thought that the flatness is lost if it can not be absorbed by the
That is, when a film having a small heat shrinkage rate is used, the film surface after bonding
does not have an appropriate tension, so that the film surface becomes wavy and it is difficult to
mount as a flat film surface. In the above example, aluminum is used as the casing frame 11 and
a polyester film is used as the film. However, the difference in thermal expansion is caused by the
material and material of the members used as the casing frame 11 and the material of the film
used as the support layer 10 Will be different. However, even when aluminum, which has a large
thermal expansion among metals, is used for the casing frame, as in the case of a polyester film,
if the heat shrinkage ratio is 1.2% or more, the flatness can be easily secured. By using a material
having a heat contraction rate of 1.2% or more as the film used as the support layer 10 of the
form, the film can be adhered to the casing frame 11 with an appropriate tension.
[0039]
As the adhesive used in the present embodiment, any adhesive can be used as long as it can bond
the film serving as the support layer 10 and the casing frame 11. However, it is preferable that
the heat curing temperature is not too high. Specifically, the heat curing temperature is
preferably in the range of 80 ° C. or more and 120 ° C. or less. In particular, a silicone-based
adhesive is suitable because it easily adheres to both the polyester film and the metal of the
casing frame 11, and the curing temperature thereof can be used generally in the range of 80 °
C to 120 ° C.
[0040]
04-05-2019
12
(Manufacturing method) Next, the manufacturing method of the probe of this embodiment is
explained in detail. First, the light reflection layer 6 is formed on a film to be the support layer
10. When a metal thin film is used as the light reflecting layer 6, the light reflecting layer 6 can
be formed on the film to be the support layer 10 by vapor deposition, sputtering or the like.
When Au is used, the adhesion is often weak. Therefore, after forming a Cr film as a base layer, it
is preferable to form an Au film. In addition, surface treatment such as ozone asher may be
performed. In addition, it is also possible to form a dielectric layer of an oxide film such as TiO 2
instead of a metal thin film on a film in multiple layers.
[0041]
Next, the support layer 10 having the light reflection layer 6 formed thereon is adhered to the
housing frame 11. The support layer 10 may be subjected to stress or the like of the light
reflection layer 6. In order to provide the light reflection layer 6 on the probe in a flat state, it is
preferable that an appropriate tension be applied to the support layer 10. Such a state can be
realized by making the heat-shrinkable support layer 10 be in pressure contact with the casing
frame 11 and thermally curing the adhesive in a pressurized state. The portion to which the
support layer 10 is bonded is the end face of the frame defining the outer shape of the housing
frame 11. The housing frame 11 preferably has a small thickness in order to make the entire
probe compact, but in order to bond it, the frame area should be large. It is preferable to
determine the frame thickness of the housing frame 11 in view of both of these surfaces.
Specifically, the frame thickness may be 100 μm or more and 10 mm or less.
[0042]
Specifically, the adhesion of the support layer 10 to the housing frame 11 may be performed by
the following method. Although the method of bonding the case frame 11 made of SUS is
described as an example of the case frame 11, other materials can be used by appropriately
selecting an adhesive. First, after the upper end surface 12 of the housing frame 11 is wiped and
cleaned with an organic solvent, a primer is applied to the end surface. The primer is a low
viscosity liquid to facilitate adhesion of the surface, and it is preferable to use one more suitable
for the type of adhesive. After the primer is applied to the upper end surface 12, the solvent is
evaporated and heat treatment for fixing is performed. Next, an adhesive is applied to the upper
end surface 12. The adhesive used is preferably a silicone adhesive, but it is also possible to use
an epoxy adhesive or an acrylic adhesive.
04-05-2019
13
[0043]
Next, the support layer 10 on which the light reflection layer 6 is formed is temporarily fixed on
a flat plate, and the adhesive surface of the support layer 10 is pressed against the upper end
surface 12 of the casing frame 11 coated with the adhesive. While being pressure-fixed, heat
curing treatment is performed. Since the support layer 10 such as a polyester film shrinks in the
curing process, it is adhesively fixed in a state where an appropriate tension is applied. Therefore,
even if it returns to room temperature, the flat light reflection layer 6 can be formed.
[0044]
Next, in a state in which the light reflecting layer 6 is attached to the housing frame 11, the
inside of the housing is filled with an acoustic matching agent to be the acoustic matching layer
9. As the acoustic matching agent, it is preferable to use a silicone rubber obtained by
crosslinking an organic polymer based on PDMS (polydimethylsiloxane). It is also possible to use
one in which silica particles and the like are added to PDMS, and fluorosilicone in which part of
hydrogen of PDMS is substituted with fluorine. The organic polymer is filled inside the housing
by dropping the organic polymer before crosslinking. The filling amount may be determined so
that the substrate 3 on which the element 1 to be inserted next is built is sufficiently embedded
in the organic polymer. After adding the organic polymer, vacuum treatment is performed. This is
to remove air bubbles originally contained in the air bubbles and the organic polymer involved at
the time of filling.
[0045]
Next, the capacitive transducer 33 is inserted into the housing. FIG. 4 is a schematic view
showing an example of connection between the capacitive transducer 33 and the flexible
substrate 14. The substrate 3 on which the element 1 is formed is fixed to the device board 13.
The device board 13 can use a glass epoxy substrate or the like. At the end portion of the device
board 13, the electrode terminal of the capacitive transducer and the flexible substrate 14 are
wire-bonded to each other, and the bonding portion is sealed by a sealing portion 15. The
electrical connection may be performed not only by wire bonding but also by ACF or the like.
04-05-2019
14
[0046]
Thus, the capacitive transducer 33 connected to the flexible substrate 14 is inserted into the
inside of the housing filled with the acoustic matching agent. FIG. 5 is a schematic view showing
an example when the capacitive transducer 33 is inserted into the housing. The capacitive
transducer 33 is inserted into the housing from the side on which the element 1 is formed, but in
order to prevent air bubbles from being caught, the capacitive transducer 33 is pushed at a
sufficiently low speed to make the capacitive transducer 33 an acoustic matching agent. Bury in
the The thickness of the portion to be the acoustic matching layer 9 is determined by the
distance between the receiving surface of the capacitive transducer 33 and the support layer 10
bonded to the housing frame 11. Therefore, at the time of insertion, it is preferable to monitor
the pressing amount of the receiving surface so that no inclination occurs. Specifically, it is
preferable to press the device board 13 at a plurality of points using the pressing jig 16 so that
no inclination occurs.
[0047]
Thus, when the embedding of the capacitive transducer 33 in the organic polymer which is the
acoustic matching agent is completed, the casing container is put into the thermosetting furnace
with the embedded portion in the lower side in the gravity direction. The curing conditions are
determined by the temperature and the holding time, but it is preferable in the process to
increase the holding time without raising the curing temperature. Usually, in PDMS, the curing
temperature is selected from 80 ° C. to 120 ° C., and the holding time is selected from about 3
hours to 24 hours.
[0048]
The thus formed probe has the acoustic matching layer 9 on the vibrating film 7 of the element 1
on the receiving surface of the probe, and the light reflecting layer 6 is formed on the acoustic
matching layer 9 through the support layer 10 . As a result, the support layer 10 supports the
light reflection layer 6 and the stress of the light reflection layer 6 does not reach the acoustic
matching layer 9 and the vibrating film 7 very much. Therefore, deformation or the like of the
vibrating film 7 does not easily occur, and even though the light reflecting layer 6 is disposed,
the variation in the performance of the probe can be suppressed and the acoustic wave can be
favorably received.
04-05-2019
15
[0049]
(Object Information Acquisition Device) The probe described in the above embodiment can be
applied to an object information acquisition device that receives an acoustic wave. An acoustic
wave from the subject is received by the capacitive transducer 33 in the probe, and an electrical
signal output from the capacitive transducer 33 is used to reflect the optical characteristic value
of the subject such as the light absorption coefficient. Information in the sample can be acquired.
[0050]
FIG. 6 shows a subject information acquisition apparatus using the photoacoustic effect. The
pulsed light 52 generated from the light source 51 is irradiated to the subject 53 via an optical
member 54 such as a lens, a mirror, or an optical fiber. The light absorber 55 inside the subject
53 absorbs the energy of the pulsed light and generates an acoustic wave 56. The probe 57
receives the acoustic wave 56, converts it into an electric signal, and outputs the electric signal to
the signal processing unit 59. The signal processing unit 59 performs signal processing such as A
/ D conversion and amplification on the input electric signal, and outputs the signal processing to
the data processing unit 50. The data processing unit 50 acquires, as image data, object
information (object information reflecting the optical characteristic value of the object such as a
light absorption coefficient) using the input signal. The display unit 58 displays an image based
on the image data input from the data processing unit 50. The probe may be one that scans
mechanically or one that is moved by a user such as a doctor or an engineer relative to the
subject (handheld type).
[0051]
Example 1 Hereinafter, a first example will be described as an example of a method for
producing a probe. The case frame 11 of the probe was made of SUS. As the support layer 10, a
polyethylene terephthalate film (Lumira-F-65 manufactured by Toray Industries, Inc.) having a
thickness of 12 μm was used. A laminated film of an adhesion layer of 10 nm of Cr film and 150
nm of Au film was formed by vapor deposition to form a light reflection layer 6. The step of
attaching the support layer 10 to the housing frame 11 was performed as follows.
[0052]
04-05-2019
16
First, the upper end surface 12 (see FIG. 3) was wiped and cleaned with an organic solvent to
wipe out oil and dust. Next, in order to secure the adhesive strength of the silicone adhesive, a
dedicated primer No. 4 was applied to the end face. Primer No. 4 is a primer exclusively for
silicone resin made by Shin-Etsu Chemical Co., Ltd., and is for securing the adhesive strength
between the silicone adhesive and SUS. The coating was applied to the upper end surface 12 of
the SUS frame, and heat treatment was performed in a furnace at 80 ° C. for 30 minutes for
solvent volatilization and fixing.
[0053]
Next, a silicone adhesive was applied to bond the polyester film. As an adhesive, Shin-Etsu
Chemical X-32-949 was used. Particulate powder is mixed in the adhesive. 5 phr (parts per
hundred parts of resin) from Potters-Ballotini Ltd. were added and mixed thoroughly by
centrifugal degassing with thorough mixing.
[0054]
The adhesive was applied by transfer. Transfer is a method of slidingly filling an adhesive in a
concave portion set to a predetermined film thickness and transferring it onto the upper end
surface 12 of the SUS frame. The film thickness of the adhesive was 50 to 200 μm.
[0055]
Next, the polyester film was attached. First, the polyester film was temporarily fixed to a plate
having a flat surface made of metal with the adhesive surface directed to the SUS frame side. The
temporary fixing may be performed with an adhesive tape or the like so as not to loosen the film.
Next, the plate was brought into contact with the end face of the SUS frame. The plate is
pressurized and held on the SUS frame by its own weight or a spring or the like, and is thermally
cured in the held state. The heat curing conditions were performed at 120 ° C. for 60 minutes.
After heat curing of the adhesive, the polyester film is adhesively fixed in a flat state.
[0056]
04-05-2019
17
Next, PDMS which will be the acoustic matching layer 9 was filled in the casing container in a
state in which the support layer 10 on which the light reflection layer 6 is formed is stretched.
PDMS (Shin-Etsu Chemical X-32-1619) was dropped directly from the tube into a SUS frame case
container. In the present embodiment, it was dropped to a depth of about 5 mm. Next, a vacuum
degassing treatment was performed to remove air bubbles caught in the dropping and air
bubbles contained in PDMS. Specifically, it was left for 30 minutes or more in a vacuum of 5 ×
10 <-2> Torr or less.
[0057]
Next, the capacitive transducer 33 was embedded in the PDMS dropped into the SUS frame case
container. As shown in FIG. 4, the capacitive transducer 33 is fixed to a glass epoxy device board
13. The capacitive transducer 33 mounted in this manner was embedded while slowly pushing
the surface of the capacitive transducer on the side of the vibrating film 7 toward the polyester
film surface so as not to cause air bubbles. The distance between the capacitive transducer 33
and the polyester is calculated from the amount of indentation. In addition, the device board 13
was pressed at a plurality of points using the pressing jig 16 described in FIG. 5 so that no
inclination occurs.
[0058]
In this way, the top of the sealing portion 15 of the wire bonding and the polyester surface are
pressed to such an extent that they contact. The film thickness of the PDMS of the acoustic
matching layer 9 formed by the method of the present embodiment is determined by the height
of the sealing portion 15. In the present embodiment, the film thickness of the acoustic matching
layer 9 is formed to be 300 to 500 μm. Next, in a state where the capacitive transducer 33 is
embedded, the SUS frame case container is hollow so that the support layer 10 faces down and
the surface of the light reflection layer 6 is not in contact with anything, It was put into a heat
curing furnace. The curing conditions were 80 ° C. for 15 hours.
[0059]
Since the light reflection layer 6 excellent in flatness is realized on the support layer 10 in the
probe formed as described above, the variation in performance is suppressed and the
photoacoustic wave can be favorably received.
04-05-2019
18
[0060]
DESCRIPTION OF SYMBOLS 1 element 2 cell structure 3 silicon substrate 4 support part 5 gap 6
light reflection layer 7 vibrating film 8 2nd electrode 9 acoustic matching layer 10 polyester film
11 case frame 12 upper end surface 13 device board 14 flexible substrate 15 sealing agent 16
Pressure jig
04-05-2019
19
Документ
Категория
Без категории
Просмотров
0
Размер файла
33 Кб
Теги
jp2014076242
1/--страниц
Пожаловаться на содержимое документа