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The present invention relates to an ultrasonic probe and a method of manufacturing the same.
(B) Prior Art Generally, in a linear scanning type ultrasonic probe, a large number of piezoelectric
elements arranged in an array are provided, and on the surface of these piezoelectric elements, a
matching layer for acoustic matching with an object? Also, a back layer for ultrasonic absorption
is provided on the back of the piezoelectric element. The piezoelectric element has a structure in
which the scanning line density of the ultrasonic beam is improved by narrowing the pitch
intervals of these elements, and single vibration of thickness vibration of the piezoelectric
element is achieved to suppress the generation of the site lobe. It is widely adopted. For the
matching layer, for example, in the case of a two-layer structure, the first matching layer on the
piezoelectric element side has a sheath S of 10 to 20 О 10 6 S, and the second matching on the
object side in order to achieve acoustic matching between the piezoelectric element and the
subject. In the layer, an acoustic impedance of 3 to 10 y 106% и S is required. Therefore, quartz
glass or the like is selected for the first matching layer, and epoxy resin or the like is selected and
used for the second matching layer. On the other hand, from the viewpoint of the structure of the
matching layer, it is preferable in terms of acoustic characteristics to make the array array cut
like a strip like the piezoelectric element in terms of acoustic characteristics. Is extremely difficult
to process. For this reason, the conventional matching layer has a structure in which one
substrate is commonly joined to each piezoelectric element in each layer. However, in such a
structure, crosstalk occurs when the piezoelectric element is excited, and the resolution is
lowered, so that the performance of the arrayed piezoelectric element can not be sufficiently
exhibited. (C) Purpose The present invention solves the above conventional problems and forms a
matching layer which can fully exhibit the characteristics of the arrayed piezoelectric elements
without impairing the acoustic matching property, thereby providing excellent acoustic
characteristics. It aims at providing an ultrasound probe. The ultrasonic probe according to the
present invention comprises a plurality of piezoelectric elements arranged in an array and a
matching layer provided on the surface of the piezoelectric element, and at least one matching
layer on the piezoelectric element side is made of glass A metal layer of nickel-chromium alloy,
aluminum or the like is formed in a comb shape on a substrate, and the width of each metal layer
in the array arrangement direction is set smaller than the pitch width of each piezoelectric
element. It is characterized by In addition, when manufacturing this ultrasonic probe, a glass
substrate is prepared, and a photoetching method is applied on the glass substrate to form a
metal layer such as nickel-chromium alloy or aluminum in a comb shape, thereby It is
characterized in that the obtained matching layers are adhered in common over a plurality of
piezoelectric elements arranged in an array.
The present invention will be described in detail based on an embodiment shown in the drawings.
FIG. 1 is a side sectional view of the ultrasonic probe of this embodiment, and FIG. 2 is a sectional
view taken along the line II--II of FIG. The ultrasound probe 1 of this embodiment comprises a
plurality of piezoelectric elements 2 arranged in an array. That is, the piezoelectric elements 2
are arranged in parallel with each other with a predetermined gap 4 therebetween. Each
piezoelectric element 2 is configured by forming electrodes 8a and 8b on the opposing main
surfaces of a piezoelectric substrate 6 such as lead zirconate titanate PZT. First and second
matching layers 10 and 12 for acoustic matching and acoustic lens 14 are sequentially stacked
on the surface (upper side in the figure) of these piezoelectric elements 2, and the back of
piezoelectric element 2 is covered A back layer 16 for ultrasonic absorption is provided. The
above first one. Both second matching layers 10.12 have a thickness near the ? wavelength.
Further, as shown in FIG. 3, the first matching layer 10 has a metal layer 20 of nickel-chromium
alloy, aluminum, etc. or a comb-tooth having a predetermined gap 24 on a quartz glass or
Noricon glass substrate 18. The width d of each metal layer 20 in the array arrangement
direction is set to be sufficiently smaller than the pitch width p of each piezoelectric element 2.
The gaps 24 between the metal layers 20 are filled with an adhesive (not shown) such as epoxy
resin. On the other hand, the second matching layer 12 is formed of one plastic plate made of
epoxy resin / resin or the like. Reference numerals 22a and 22b denote the respective electrodes
Qa of the piezoelectric element 2. It is a lead connected to 8b. Next, a method of manufacturing
the ultrasonic probe 2 will be described. First, a piezoelectric diaphragm provided with electrodes
and IJ-) wires 22a and 221) on the facing surface of a piezoelectric parent substrate such as PZT
is prepared, and this piezoelectric diaphragm is fixed to the back layer 16. Then, the piezoelectric
diaphragm is cut at predetermined intervals by a grindstone, thereby forming the arrayed
piezoelectric elements 2. On the other hand, the first matching layer 10 is manufactured by the
process as shown in FIG. The first matching layer 10 is basically formed by applying a
photoetching method. That is, a glass substrate 18 of quartz glass type or noricon type is
prepared and a gold-plated film such as a 1.7 chromium alloy or aluminum is vapor-deposited on
the entire surface of the glass substrate 1B (step II). Instead of this deposition, chemical plating,
sputtering or the like may be applied to form a metal film. Next, a resist film is applied over the
entire surface of the metal film, and dried (step III).
Subsequently, a mask aligned with the gap 24 between the metal layers 20 to be formed is
disposed on the resist film, alignment is performed, and then exposure is performed to sensitize
the resist film (step {circle over (3)}). Since the resist film on the exposed portion hardens, next,
when this phenomenon occurs, the resist film at the portion shielded by the mask, that is, the
position to be the gap 24 is dissolved and only the resist film at the position to be the metal layer
20 remains. (Step V). Subsequently, the exposed resist film is baked and stabilized, and then a
corrosive solution is sprayed over the entire surface. As a result, the metal film at the portion
where the resist film has disappeared is etched (step {circle over (3)}). Next, when the remaining
resist film is dissolved and removed, a metal layer 2 o having a predetermined gap 24 is formed
on the glass substrate 18. However, since the metal layer 20 having a sufficient thickness can not
be obtained by performing the above process only once, the process from the step H to the step
6 is repeated a plurality of times. Thus, the obtained first matching layer 10 bonds the glass
substrate 18 commonly over the respective piezoelectric elements 2, and the gap 24 between the
metal layers 20 is filled with an adhesive such as epoxy resin. Then, the second matching layer
12 is bonded thereon, and the acoustic lens 14 is provided on the second matching layer 12. In
the ultrasonic probe 1 formed in this manner, the direction of the object (the first one of the
ultrasonic waves emitted from each of the piezoelectric elements 12). The ultrasonic waves
emitted upward in FIG. 2 pass through the first matching layer 10 as they are, but the ultrasonic
waves emitted in the array arrangement direction orthogonal to this pass each metal layer 20 of
the first matching layer 10 Since they are separated by the gap 24, the acoustic impedance is
different and the sound is attenuated. This situation is the same as when receiving a reflected
wave from the subject. Therefore, the piezoelectric elements 2 function substantially
independently of each other, crosstalk between them is reduced, and generation of side ropes is
suppressed. As described above, according to the present invention, since the matching layer can
be formed in an array arrangement finer than the pitch interval of the arrayed piezoelectric
elements, each piezoelectric element functions independently, and each The characteristics of are
fully demonstrated. In addition, crosstalk is reduced compared to the prior art, and the site lobe
is also reduced, so that a good diagnostic image can be obtained. In recent years, there is a
tendency to increase the frequency to improve resolution. In this case, since the thickness of the
vibrator depends on the frequency, the thickness or thickness of the vibrator becomes thinner.
Therefore, the matching layer also needs to be thinned to four wavelengths, but the present
invention can address this as well.
Furthermore, using a lead titanate-based material having vibration anisotropy as the piezoelectric
element exhibits a better effect.
Brief description of the drawings
The drawing shows an embodiment of the present invention, FIG. 1 is a side sectional view of an
ultrasonic probe, FIG. 2 is a sectional view taken along the line-of FIG. 1, and FIG. 3 is a first
matching layer. FIG. 4 is a process diagram illustrating a method of forming the first matching
1 ии Ultrasonic probe, 2 и Piezoelectric element, 10 иии 1st ? ? ?1 1 и Applicant Application by
Shimadzu Corporation Patent attorney Atsushi Okada 1 Figure 1 ? m. 1 Figure 2 ~ \ Figure 3 ?
4! ? j ? ? ? ? ? ? ?? ? ? ? ? ? ? New Cabinet 1 ? ?
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description, jps60235600
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