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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.
The present invention relates to a structure of a junction between a metal body and a polymer
body in, for example, a piezoelectric transducer having high electrical reliability and excellent
water resistance and durability. Since it was discovered that the thickness and piezoelectricity of
polymer piezoelectric films can be used for electromechanical conversion, ultrasonic transducers
using this have been specifically studied. Although many considerations are needed to construct
a polymeric piezoelectric film into a practical ultrasonic transducer. In particular, attention must
be paid to the first point. 1-The first is the problem of how to form a stable electrode, and the
second is the problem of how to make an electrical connection from this electrode to another
system, sixth Is how to improve the so-called stability and reliability, such as water resistance,
durability, and stability against external electrical noise. A transducer using a conventional
polymer piezoelectric film. Although some known examples exist regarding the structure of the
ultrasonic transducer, in particular, they can not be said to be sufficiently grooved in the
reliability and stability described above. For example, an ultrasonic transducer used in an
ultrasonic diagnostic apparatus is used after being immersed in water for a long time, but in this
case, extremely strong water resistance is required. Moreover, the transducer for ultrasonic flaw
detection is mechanically subjected to a large impact or friction depending on the conditions of
use. An ultrasonic transducer using a polymeric piezoelectric film that can be used under such
circumstances has not been obtained conventionally. The present invention relates to a structure
having a junction of a metal body and a polymer body, such as the above-mentioned conventional
transducer, and is extremely reliable electrically. It provides a bonded body excellent in water
resistance and durability, and has an eight-order configuration. That is, in a bonded body of a
metal body and a polymer body, a bonded body of a metal body and a polymer body in which the
metal film surface and the metal body surface of the polymer body in which the metal film is
formed in advance are soldered. Next, an ultrasonic transducer will be described in more detail as
an example of a joined body of a metal body and a polymer body according to the present
invention. FIG. 1 is a schematic view showing the basic structure of an ultrasonic transducer
according to the present invention. In FIG. 1, 1 is a polymer piezoelectric film, 2 is a back side
electrode, 3 is a front side electrode made of a metal film, 4 is a surface addition film made of a
polymer material, 5 is a conductive metal case, 6 is a solder It is. In order to prevent the
electrode of the polymer piezoelectric film from being corroded, it is necessary to strengthen the
water resistance of the ultrasonic transducer so that the component 1 chemically reacting with
the electrode, for example, water does not intrude into the electrode portion.
According to the present invention, a conductive metal case 5 made of a metal body and a
surface plated film 4 made of a polymer material are soldered to each other through the front
side electrode 3 formed on the surface of the surface addition film 4. Therefore, the metal body
of the transducer and the polymer body are joined to make it possible to completely waterproof
the transducer. The front side electrode 6 is, for example, Cu, Cr, Ni, Au, etc., which can be
prepared by chemical plating, vapor deposition or other ordinary methods, and can be preferably
soldered with the conductive metal case 5 . The surface addition film 4 is preferably an aromatic
polyamide, an aromatic polyimide or the like having high heat resistance from the viewpoint of
adhesion to the electrode and soldering to the metal case 5 after adhesion, but the metal
electrode is firmly adhered in a film And if soldering does not cause melting or significant
deformation at temperature. Any polymer membrane can be used. According to the configuration
of the transducer according to the present invention as described above, the surface addition film
4 is firmly attached to the conductive metal case 5 via the front side electrode 6 provided on the
upper surface thereof, and Since the adhesion between the surface addition film 4 and the
electrode 6 is also strong, it is mechanically stable. Therefore, as long as the 9 surface additional
film 4 is excellent in water resistance, it is also extremely water resistant as a transducer, and the
reliability of a transducer using a polymer piezoelectric film which has been concerned with the
prior art is enhanced . EXAMPLE An ultrasonic transducer of the structure shown in FIG. 2 was
produced. Here, 11 is a piezoelectric film made of polyvinylidene fluoride which has been
subjected to holeing, 12 is a back side electrode made of a copper plate molded into a concave
surface, 13 is 1 μm by electrolytic plating on the upper surface of a surface additional film 14
made of aromatic polyamide of 25 μm thickness. A front side electrode made of a copper film
attached to a thickness of 15, a metal case 15 made of brass, a plastic case 17 covering the metal
case 15, and a support substrate 18 made of Bakelite. The conductive metal case 15 and the
front side electrode / surface additional film indicated by 13.14 were bonded by a solder 16. The
other parts in FIG. 2 except for the parts bonded by the solder 16 were bonded with an epoxy
adhesive. 5-The ultrasonic transducer thus produced was left in water for 5 months to measure
the insertion loss of the transducer and the temporal change of the pulse drive waveform, but no
major change was observed. On the other hand, for comparison, a transducer with a surface
addition film on which M is deposited as an electrode which can not be soldered is adhered to a
metal case by an epoxy adhesive via an M electrode surface is left in water as described above.
One month after immersion, it was confirmed that the M electrode deteriorated.
As described above, by forming a joined body of a metal body and a polymer body according to
the present invention, a joined body 9 having high electrical reliability, in particular, significantly
improved water resistance and durability, for example, an ultrasonic transformer We can provide
some resources. In the present invention, an ultrasonic transducer with a large number of
transducer elements, for example, a hearing aid array. It is natural that the present invention can
be effectively applied to multi-element type transducers such as a linear array or an animation
array. 6-Also, the metal case described here does not necessarily have to be a box box body, and
a front side electrode 26 and a solder 26 in which a metal frame as shown at 25 in FIG. The
attachment may be provided in a possible ring shape. Furthermore, as schematically shown in
FIG. 4, when attaching the back and front side electrodes 32. 33 to the piezoelectric film filter 1
as well, the ring-shaped metal frame 35 similar to FIG. Hydrophones that can be made to operate
in water in this embodiment. Alternatively, there are many other applications as various
electroacoustic transducers.
Brief description of the drawings
1 schematically shows an ultrasonic transducer having a structure according to the present
invention, FIG. 2 is a longitudinal sectional view showing an embodiment of the ultrasonic
transducer according to the present invention, FIG. FIG. 2 is a schematic view showing an
ultrasonic transducer of an embodiment in which the metal case in FIG. 2 is formed into a ring
shape, and FIG. 4 is one embodiment of the present invention. 1: polymer piezoelectric film 3 =
front side electrode 4: surface additional film 5: metal case 8: wire
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