JP3749192B2 - Ultrasonic transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic transducer mainly used in an ultrasonic endoscope that images a tomography in a living body using an ultrasonic echo.
[0002]
[Prior art]
2. Description of the Related Art In recent years, an ultrasonic diagnostic apparatus that obtains an ultrasonic tomographic image by irradiating a living body with ultrasonic waves, receiving reflected ultrasonic waves reflected by a changing portion of acoustic impedance in the living body, converting them into electrical signals, and imaging them. Became widely used.
[0003]
An ultrasonic endoscope in which an ultrasonic transducer is provided at the distal end of an endoscope insertion portion that can be inserted into a body cavity and an ultrasonic tomographic image can be obtained by this ultrasonic transducer has been put into practical use. .
[0004]
The piezoelectric element of the ultrasonic transducer used in the ultrasonic endoscope is made of a piezoelectric material such as lead zirconate titanate (PZT) or lead titanate (PbTiO3). This piezoelectric element has a large acoustic impedance. For this reason, in order to efficiently propagate ultrasonic waves to the subject, the piezoelectric element has an optimal acoustic impedance as an acoustic matching layer, for example, a resin film made of epoxy resin or a resin layer mixed with alumina, A resin layer mixed with glass and a resin layer mixed with metal were provided.
[0005]
However, in the configuration in which the gold electrode is provided on the piezoelectric element, sufficient adhesion strength cannot be obtained even when the gold electrode and the resin film or resin layer are bonded using, for example, an epoxy adhesive. Therefore, γ-glycidoxypropyltrimethoxysilane, which is generally recommended to correspond to the epoxy resin, has the property of roughening the adhesion surface of the gold electrode or chemically bonding an organic material and an inorganic material. A silane coupling agent containing as a main component was used.
[0006]
[Problems to be solved by the invention]
However, the bonding method for roughening the bonding surface of the gold electrode is not only troublesome, but has not been able to obtain such a high bonding strength. Further, even when bonding was performed using the silane coupling agent, the desired bonding strength could not be obtained. For this reason, there is a possibility that the phenomenon that the resin layer partially peels from the electrode occurs and the sensitivity is lowered.
[0007]
The present invention has been made in view of the above circumstances, improves the adhesive strength, prevents the occurrence of problems such as peeling of the resin layer from the gold electrode, and the gold electrode and the resin layer are reliably integrated and stable. An object of the present invention is to provide an ultrasonic transducer capable of obtaining the ultrasonic characteristics.
[0008]
[Means for Solving the Problems]
An ultrasonic vibrator according to the present invention is an ultrasonic vibrator including a piezoelectric element provided with a gold electrode and a resin layer in which an acoustic impedance that is bonded and fixed to the gold electrode of the piezoelectric element is set in a predetermined range. ,
A predetermined amount of a silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane is mixed in a predetermined adhesive that bonds and fixes the gold electrode of the piezoelectric element and the resin layer.
[0009]
Alternatively, an ultrasonic vibrator comprising a piezoelectric element provided with a gold electrode and a resin layer in which an acoustic impedance bonded and fixed to the gold electrode of the piezoelectric element is set within a predetermined range,
A silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane is applied in advance to at least one of the adhesion surfaces of the gold electrode of the piezoelectric element and the resin layer, and the gold electrode and the resin layer of the piezoelectric element are applied. Are fixed with a predetermined adhesive.
[0010]
According to these configurations, the adhesive fixing strength between the gold electrode and the resin layer is significantly improved by using the silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane together with the adhesive.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
1 to 3 relate to an embodiment of the present invention, FIG. 1 is a perspective view showing a schematic configuration of an ultrasonic transducer, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. It is a figure explaining other structures.
[0013]
As shown in FIG. 1 and FIG. 2, the ultrasonic transducer 1 of the present embodiment is a flat plate having a piezoelectric characteristic as an ultrasonic transducer and a substantially circular piezoelectric element 2, and emits ultrasonic waves or transmits / receives ultrasonic waves. A front electrode 3a, which is a gold electrode formed by sputtering on an ultrasonic radiation surface or an ultrasonic transmission / reception surface (also simply referred to as a front surface), and a surface opposite to the ultrasonic radiation surface of the piezoelectric element 2 (with respect to the front surface) The rear electrode 3b, which is a gold electrode provided with gold on the rear surface), and the acoustic impedance of the piezoelectric element 2 laminated on the front electrode 3a of the piezoelectric element 2 by the first adhesive 4a and the acoustic impedance of the living body. An acoustic matching layer 5 formed of a resin layer such as an epoxy resin, a polyimide resin, or an ultem resin and an alumina-containing resin layer that increases sound efficiency so as to eliminate the gap, and a thickness dimension of which is a wavelength (λ) / 4, and The resin acoustic lens 6 serving as a focusing means for focusing the ultrasonic wave emitted from the piezoelectric element 2 to emit an ultrasonic beam, and the second electrode 4b are laminated on the rear electrode 3b of the piezoelectric element 2, A backing material 7 made of, for example, rubber containing ferrite for attenuating ultrasonic waves to the rear side, a part of the piezoelectric element 2, the front electrode 3 a, the rear electrode 3 b, the acoustic matching layer 5, the acoustic lens 6 and the backing material 7. It is mainly composed of a protective film 8 made of parylene (polyparaxylylene) having excellent water resistance and chemical resistance covering each surface.
[0014]
The first adhesive 4a is mixed with 1-2% of a silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane, which is generally recommended as an epoxy adhesive for rubber. It is a thing.
[0015]
The acoustic matching layer 5 is bonded and fixed to the front electrode 3a of the piezoelectric element 2 using the first adhesive 4a mixed with the silane coupling agent, so that the γ-glycidoxypropyltrimethoxysilane is the main component. Compared with adhesive fixing using an epoxy adhesive containing a silane coupling agent or an epoxy adhesive not containing a silane coupling agent, the acoustic matching layer 5 is partially formed from the front electrode 3a of the piezoelectric element 2. Peeling is improved, and it is securely bonded.
[0016]
The ground electrode 9a is electrically connected to the front electrode 3a, and the signal line 9b is electrically connected to the rear electrode 3b. These electric wires 9a and 9b are collectively extended as a lead wire 9 and connected to a signal terminal and a ground terminal of an ultrasonic observation apparatus (not shown).
[0017]
The acoustic lens 6 provided in the acoustic matching layer 5 is formed and arranged with respect to the acoustic matching layer 5 formed to have a predetermined thickness, and the epoxy resin of the same member as the acoustic matching layer 5 is acoustically used. It is laminated on the ultrasonic radiation surface of the matching layer 5 and formed into a concave curved surface shape that continuously changes in thickness as it goes from the center to the circumferential direction. In the present embodiment, the thickness dimension of the central portion of the acoustic lens 6 is set to zero with respect to the ultrasonic radiation surface of the acoustic matching layer 5. That is, the central portion of the acoustic lens 6 and the ultrasonic radiation surface of the acoustic matching layer 5 coincide. The acoustic velocity condition of the acoustic lens 6 is set faster than water (living body).
[0018]
Thus, when adhesively fixing the front electrode of the piezoelectric element and the acoustic matching layer, by using an adhesive mixed with a predetermined amount of a silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane, Adhesive strength can be greatly improved.
[0019]
As a result, the acoustic matching layer is securely bonded and fixed to the front electrode of the piezoelectric element without being peeled off during the manufacturing process, and the ultrasonic transducer having a stable sensitivity and bandwidth, that is, having a good ultrasonic characteristic. Can provide.
[0020]
As shown in FIG. 1 and FIG. 2, the adhesive between the piezoelectric element 2 and the acoustic matching layer 5 is a first adhesive containing a predetermined amount of a silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane. In place of 4a, the silane coupling agent 10 is applied in advance to one surface of the acoustic matching layer 5 on the front electrode 3a side or the surface of the front electrode 3a of the piezoelectric element 2, and then the epoxy Even if the piezoelectric element 2 and the acoustic matching layer 5 are bonded and fixed with an adhesive of the same type, similar actions and effects can be obtained.
[0021]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.
[0022]
【The invention's effect】
As described above, according to the present invention, the adhesive strength is improved, the occurrence of problems such as the resin layer peeling from the gold electrode is prevented, and the gold electrode and the resin layer are reliably integrated and stable ultrasonic waves. An ultrasonic transducer capable of obtaining characteristics can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of an ultrasonic transducer. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 3 is a diagram for explaining another configuration of an ultrasonic transducer.
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic vibrator 2 ... Piezoelectric element 3a ... Front electrode 4a ... Adhesive 5 ... Acoustic matching layer

Claims (2)

In an ultrasonic transducer comprising a piezoelectric element provided with a gold electrode and a resin layer in which an acoustic impedance bonded and fixed to the gold electrode of the piezoelectric element is set within a predetermined range,
An ultrasonic vibration characterized in that a predetermined amount of a silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane is mixed in a predetermined adhesive for bonding and fixing the gold electrode of the piezoelectric element and the resin layer. Child. In an ultrasonic transducer comprising a piezoelectric element provided with a gold electrode and a resin layer in which an acoustic impedance bonded and fixed to the gold electrode of the piezoelectric element is set within a predetermined range,
A silane coupling agent mainly composed of γ-mercaptopropyltrimethoxysilane is applied in advance to at least one of the adhesion surfaces of the gold electrode of the piezoelectric element and the resin layer, and the gold electrode and the resin layer of the piezoelectric element are applied. And an ultrasonic transducer characterized by being bonded and fixed with a predetermined adhesive.

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