WO2016085014A1

WO2016085014A1 - Multi-layer ultrasonic transducer and method for manufacturing same

Info

Publication number: WO2016085014A1
Application number: PCT/KR2014/011570
Authority: WO
Inventors: 신은희; 김희원; 이상웅; 이재원; 김성학
Original assignee: 알피니언메디칼시스템 주식회사
Priority date: 2014-11-28
Filing date: 2014-11-28
Publication date: 2016-06-02

Abstract

Disclosed are a multi-layer ultrasonic transducer and a method for manufacturing the same. The multi-layer ultrasonic transducer according to an embodiment of the present invention comprises: an active element consisting of a plurality of layers; and a flexible printed circuit board which is a single metal layer, directly coupled to one surface of at least one layer consisting of the active element, for supplying electrical signals.

Description

Multilayer Ultrasonic Transducer and Manufacturing Method Thereof

The present invention relates to an ultrasonic transducer for acquiring image information inside an object under examination using ultrasonic waves.

The ultrasound diagnosis apparatus is an apparatus for imaging an internal tissue of an object by using an ultrasound signal reflected by an ultrasound signal. The ultrasound diagnosis apparatus may transmit the ultrasound signal to a diagnosis part of the subject, and then acquire the image information of the diagnosis part by receiving an ultrasound signal reflected from the boundary of tissues inside the subject having different acoustic impedances. Can be.

The ultrasonic diagnostic apparatus includes an ultrasonic transducer for transmitting an ultrasonic signal to the subject and receiving an ultrasonic signal reflected by the subject. Ultrasonic transducers generally include an active element, a matching layer, and a backer. With the recent development of the manufacturing technology of the ultrasonic transducer, the pitch of the active elements is reduced and the number thereof is increased to increase the lateral resolution.

According to an embodiment, there is proposed a multilayer ultrasound transducer and a method of manufacturing the same, which improve acoustic performance, impedance mismatch with a cable, and simplify the manufacturing process.

An ultrasonic transducer according to an embodiment includes an active element composed of a plurality of layers, and a flexible printed circuit board, which is a single metal layer that is directly coupled to one surface of at least one layer constituting the active element to supply an electrical signal. do. The flexible printed circuit board may be a single conductive metal flake having a circuit pattern formed thereon.

The flexible printed circuit board may be bonded to one surface of at least one layer of the active device, and an active region of the flexible printed circuit board, which is bonded to one surface of the active device, may be formed of a conductive material corresponding to the formation of the one surface. . The ultrasonic transducer further includes a ground layer, which is a single metal layer electrically connected to the active element.

Meanwhile, an ultrasonic transducer according to another embodiment may include an active device including an even layer including a first layer and a second layer, and a rear surface of a first layer of the active device, generated from the active device, A backing material that blocks or attenuates the ultrasonic waves propagated to the first layer, a matching layer positioned on the front surface of the second layer and matching the acoustic impedance of the ultrasonic waves generated by the active element and propagated to the front surface, and the first of the active elements. The flexible printed circuit board includes a single metal layer positioned between the layer and the second layer and electrically connected to the active device.

The flexible printed circuit board may be a single conductive metal flake having a circuit pattern formed thereon. The flexible printed circuit board is bonded to one surface of the first layer and the second layer of the active element, respectively, and the activation area of the flexible printed circuit board is bonded to the one surface of the first layer and the second layer of the active element. It may be composed of a conductive material corresponding to the formation of.

An ultrasonic transducer according to an embodiment may include a first ground layer, which is a single metal layer positioned between a first layer of an active element and the backing material and electrically connected to the active element, and a second layer of the active element. And a second ground layer disposed between the matching layers, the second ground layer being a single metal layer electrically connected to the active element. The active element may be a plurality of piezoelectric elements. The matching layer may be composed of a plurality of layers.

On the other hand, the ultrasonic transducer according to another embodiment, the active element is stacked with an odd layer including a first layer, a second layer and a third layer, and the active element is located on the back of the first layer of the active element A backing material for blocking or attenuating ultrasonic waves generated from the back surface, and a matching layer positioned at the front surface of the third layer and matching the acoustic impedance of the ultrasonic waves generated from the active element and propagated to the front surface; A first electrode portion, which is a single metal layer positioned between the first layer of the active element and the backing material and electrically connected to the active element, and positioned between the third layer and the matching layer of the active element; And a second electrode portion, which is a single metal layer electrically connected with the second electrode.

The first electrode part may be a flexible printed circuit board, and the second electrode part may be a ground layer. Alternatively, the first electrode part may be a ground layer, and the second electrode part may be a flexible printed circuit board.

The first electrode portion and the second electrode portion may be a single conductive metal flake having a circuit pattern formed thereon. The first electrode portion adheres to one surface of at least one layer of the active element, and the activation region of the first electrode portion adheres to one surface of the active element is made of a conductive material corresponding to the formation of the one surface, and the second The electrode unit may adhere to one surface of at least one layer of the active element, and the activation region of the second electrode unit adhered to one surface of the active element may be formed of a conductive material corresponding to the formation of the one surface. The active element may be a plurality of piezoelectric elements. The matching layer may be composed of a plurality of layers.

Meanwhile, a method of manufacturing an ultrasonic transducer according to another embodiment includes forming a flexible printed circuit board, and coupling the formed flexible printed circuit board to an active device composed of a plurality of layers. Forming a circuit board includes cutting a single layer of raw material in the form of a substrate, contacting or thermocompressing a carrier to the cut substrate, and forming a circuit pattern on the front surface of the contacted or thermocompressed substrate. And attaching a protective layer to an upper surface of the substrate except for a pattern in which the active elements are stacked. The flexible printed circuit board may be a single conductive metal flake having a circuit pattern formed thereon. The ultrasonic transducer manufacturing method may further include forming a ground layer, which is a single metal layer, and coupling the formed ground layer to the active device.

According to one embodiment, as the active device provides an ultrasonic transducer composed of a plurality of layers, capacitance and electrical impedance are reduced, thereby improving mismatch between cables.

In order to electrically connect a multi-layered active element, a flexible printed circuit board (DOUBLE side FCCL) consisting of a metal layer on the substrate layer and the substrate layer and a lower portion thereof, or on the substrate layer and the substrate layer, A single printed circuit board (Single side FCCL) in which one side of the lower portion is formed of a metal layer may be used. However, in the former case, since the impedance difference between the active elements is large, ultrasonic loss may be caused, and in the latter case, a process of etching the substrate layer to combine the active element and the metal layer should be added.

However, according to the present invention, by providing a flexible printed circuit board composed of only a single metal layer, it is possible to improve the acoustic characteristics by reducing the impedance difference, and to combine with the active element without further processing, thus simplifying the manufacturing process. And manufacturing time can be shortened.

Furthermore, in manufacturing an ultrasonic transducer composed of a plurality of active element layers, not only an ultrasonic transducer composed of odd-numbered active elements, but also an ultrasonic transducer composed of even-numbered active elements, which is difficult to manufacture, is easy and simple. Can be manufactured.

1 is a structural diagram showing an ultrasonic transducer composed of a plurality of devices according to an embodiment of the present invention,

2 is a structural diagram schematically showing the configuration of an ultrasonic transducer including an active device in which an odd number of layers are stacked according to an embodiment of the present invention;

3 is a structural diagram schematically showing the configuration of an ultrasonic transducer including an active device in which an even number of layers are stacked according to an embodiment of the present invention;

4 is a structural diagram of a general flexible printed circuit board composed of a metal layer, a substrate layer, and a metal layer;

5 is a structural diagram of a flexible printed circuit board as a metal layer according to an embodiment of the present invention;

6 is a flowchart illustrating a method of manufacturing a flexible printed circuit board of an ultrasonic transducer according to an embodiment of the present invention;

7 is a flowchart illustrating a method of manufacturing an ultrasonic transducer according to an embodiment of the present invention;

8 is a graph comparing voltage changes over time of an ultrasonic transducer and a general ultrasonic transducer according to an embodiment of the present invention;

9 is a graph comparing the change in the normal size according to the frequency of the ultrasonic transducer and the general ultrasonic transducer according to an embodiment of the present invention;

10 is a graph showing an effect of improving impedance mismatch between a general ultrasonic transducer and a cable of an ultrasonic transducer according to an embodiment of the present invention;

11 is a graph comparing the normal size versus time of a general ultrasonic transducer having a single layer active element and an ultrasonic transducer of the present invention including an active element loaded with a plurality of layers;

12 is a graph comparing voltage magnitude versus frequency of a general ultrasonic transducer having a single layer active element and an ultrasonic transducer of the present invention including an active element loaded with multiple layers.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; In the following description of the present invention, if it is determined that detailed descriptions of related well-known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intention or custom of a user or an operator. Therefore, the definition should be made based on the contents throughout the specification.

1 is a structural diagram showing an ultrasonic transducer composed of a plurality of devices according to an embodiment of the present invention.

In Fig. 1, the direction in which the array of ultrasonic transducers 1 is arranged is called the azimuth direction, and the direction in which the beam signal travels is called the axial direction. The direction orthogonal is called an elevation direction.

Referring to FIG. 1, the ultrasonic transducer 1 according to an embodiment is an array transducer having a plurality of elements 12. The larger the number of devices within the same aperture, the higher the lateral resolution and the wider acceptance angle. Therefore, the quality of the obtained ultrasound image may be improved.

However, as the number of elements 12 in the array increases within the same aperture size, the capacitance of the element 12 is lowered and the impedance is higher, resulting in an impedance mismatch with the cable. mismatch) occurs. In particular, low frequency array transducers have more severe impedance mismatches. Accordingly, the present invention proposes a multi-active layered structure in which devices are stacked in multiple layers. When the device is stacked in N layers, as can be seen in Equation 1, the capacitance C increases to N ² , and the electrical impedance decreases to N ² , thereby improving mismatch between cables.

Equation 1

In Equation 1, ε is the dielectric constant, t is the thickness of the device, and S is the area of the device.

2 is a structural diagram schematically showing the configuration of an ultrasonic transducer including an active device in which an odd number of layers are stacked according to an embodiment of the present invention.

Hereinafter, 'schematic' indicates that the depicted figure represents a relative positional or stacking relationship between components included in the ultrasonic transducer. Therefore, the specific shape or thickness of each of the components included in the ultrasonic transducer may not necessarily match those shown in the drawings.

In the present specification, when the first material layer is formed on the second material layer, it is a substrate that explicitly excludes it, as well as the case where the first material layer is formed directly on the second material layer. Unless otherwise, it is to be construed that the other third material layer includes all the intervening layers between the first material layer and the second material layer.

FIG. 2 shows an ultrasonic transducer 1a in which an active element 130 is stacked in an odd layer, for example, a first layer 131, a second layer 132, and a third layer 133. Doing. However, this is only for better understanding of the present invention, and the number of odd layers is not limited to three. Hereinafter, for convenience of description, the following description will be made with reference to the ultrasound transducer 1a having three layers stacked as shown in FIG. 2. If the active element is made of odd layers, electrical connection is easy.

Referring to FIG. 2, the ultrasonic transducer 1a may include a backer 110, a flexible printed circuit board (FPCB) 120, active elements 130, and a ground layer. ground return signal (GRS) 140, a matching layer 150, and an acoustic lens 160.

The ultrasonic transducer 1a may be an array transducer of linear or matrix shape. In the ultrasonic transducer 1a according to the exemplary embodiment, the flexible printed circuit board 120 is coupled to the rear surface of the active element 130, and the backing material 110 is coupled to the rear surface of the flexible printed circuit board 120. In addition, the ground layer 140 is coupled to the front surface of the active element 130, and the matching layer 150 is coupled to the front surface of the ground layer 140. An acoustic lens 160 is formed on the front surface of the matching layer 150.

In FIG. 2, the flexible printed circuit board 120 is positioned on the front surface of the backing material 110, and the ground layer 140 is positioned on the rear surface of the matching layer 150, but the corresponding position is the polling direction of the layer constituting the active device. It may vary. For example, the flexible printed circuit board 120 may be located at the rear of the matching layer 150, and the ground layer 140 may be located at the front of the backing material 110.

Hereinafter, each component of the ultrasonic transducer 1a will be described in detail.

The backing material 110 is configured such that the acoustic impedance is well matched with the active element 130. The backing material 110 may be configured to have sound attenuation characteristics, which are excellent sound absorption characteristics. The backing material 110 having excellent sound absorption properties suppresses the free vibration of the active element 130 formed on the front side, and not only reduces the pulse width of the ultrasonic wave, but also occurs in the active element 130 to propagate the ultrasonic wave unnecessarily to the rear side. Blocking the image effectively prevents image distortion. The backing material 110 may be formed of one or a plurality of layers using a material having a good sound absorption property. The backing material 110 may be coupled to the flexible printed circuit board 120 located at the front side, and may exchange electrical signals with the active element 130 positioned at the front surface of the flexible printed circuit board 120.

The flexible printed circuit board 120 is coupled to the rear surface of the first layer 131 of the active element 130 to supply an electrical signal to the active element 130. Flexible printed circuit board 120 is a single metal layer. The metal layer may be, for example, a copper (Cu) layer. It may be plated with a material such as gold or silver on a metal layer such as copper. The shape, arrangement pattern, thickness, and width of the electrode formed on the metal layer may vary depending on the type or characteristics of the active element 130 and / or the ultrasonic transducer 1a including the same.

Conventional flexible printed circuit boards form a metal layer, for example, a copper (Cu) layer on one substrate layer, for example, a polyimide (PI) layer to form a substrate layer (PI) -metal layer (Cu). Or a multilayer of metal layer (Cu) -substrate layer (PI) -metal layer (Cu), such as a metal layer, for example, a copper layer formed on the front and back surfaces of the substrate layer, respectively, so as to overlap two flexible printed circuit boards. It has a flexible flexible printed circuit board structure. The above-described multilayer flexible printed circuit board structure is shown in FIG. 4. However, in the multilayer flexible printed circuit board structure, since the acoustic impedances of copper (Cu) and polyimide (PI) are 44.7 and 3.4 Marayl, respectively, the acoustic impedance difference of the two materials is good for the acoustic performance. It has no effect.

The flexible printed circuit board 120 according to the exemplary embodiment of the present invention is a single metal layer. It does not consist of a substrate layer and a metal layer, but consists only of a metal layer. The metal layer is directly coupled to one surface of the active element 130 to supply an electrical signal. As the flexible printed circuit board 120 is a single metal layer, it is possible to improve acoustic characteristics due to the difference in acoustic impedance between the conventional substrate layer and the metal layer.

When the flexible printed circuit board is composed of a metal layer and a substrate layer, the substrate layer must be removed by etching in order to directly bond the metal layer to the active device. However, the flexible printed circuit board 120 according to the exemplary embodiment does not use a method of removing the substrate layer through etching, but rather, manufactures a metal layer, for example, copper foil itself using the flexible printed circuit board. Therefore, no additional process such as the etching process described above is required, and the transducer can be manufactured simply.

The active element 130 is composed of a plurality of layers. For example, as illustrated in FIG. 2, three odd layers of the first layer 131, the second layer 132, and the third layer 133 are stacked. Since the active element 130 has a stacked structure, impedance can be reduced and capacitance can be increased as compared with a structure having a single layer of active elements.

The active element 130 generates an ultrasonic signal when energy is applied to the flexible printed circuit board 120 and the ground layer 140 positioned at both ends thereof. The ultrasonic signal generated by the active element 130 according to an embodiment may have various frequencies. For example, the generated ultrasonic signals can generate signals of high frequency as well as frequencies below 17 MHz which are currently used.

The type of the active element 130 may vary depending on the type of the ultrasonic transducer 1a and may be formed of a piezoelectric element. The piezoelectric element is a part having a property of generating a voltage when mechanical pressure is applied through a piezoelectric effect, and mechanical deformation when a voltage is applied. There is no particular limitation on the shape or pattern of the piezoelectric elements. For example, the piezoelectric elements are arranged in a pattern corresponding to the electrodes of the flexible printed circuit board 120 and separated from each other. The piezoelectric element is made of a piezoelectric ceramic such as lead zirconate titanate (PZT), a single crystal, a composite piezoelectric compound of these materials and a polymer material, or a polymer material represented by polyvinylidene fluoride (PVDF). It may be formed of a piezoelectric body or the like. In addition, when fabricating a stacked structure, the same piezoelectric elements may be stacked, but other piezoelectric elements may be mixed and laminated with PZT, piezoelectric ceramic, single crystal, or the like.

The ground layer 140 is a conductive material and serves as a ground electrode. The ground layer 140 is in contact with one surface of the third layer 133 of the active device 130. The ground layer 140, like the flexible printed circuit board 120, is formed of a single metal layer. The single metal layer may be formed of a conductive metal flake, and may have ground electrodes bonded to one surface of the active element 130 in a form separated from each other to correspond to the active element 130. The ground electrode may have a cross-sectional area equal to the cross-sectional area of the third layer 133 of the active element 130 and have a predetermined thickness.

The matching layer 150 may be located in front of the third layer 133 of the active device 130 and may be coupled to the ground layer 140. The matching layer 150 suitably matches the acoustic impedance of the active element 130 with the acoustic impedance of the object under test, thereby transmitting ultrasonic waves generated by the active element 130 to the object under test and / or reflected by the object under test. The loss of ultrasonic waves (eco ultrasonic waves) is reduced. The matching layer 150 may serve as a buffer for reducing problems such as image distortion due to a sudden change in acoustic impedance between the active element 130 and the object under test.

The matching layer 150 is formed into a sheet shape using a predetermined material to have a predetermined thickness, and then made into a desired thickness and / or shape through a process such as machining, and then ground using an adhesive or the like. It may be formed in a manner that is bonded on the layer 140. For example, the matching layer 150 may correspond to the ground electrodes of the active element and / or the ground layer 140 and may be attached to each front surface of the ground electrodes in a shape separated from each other. The matching layer 150 may have the same cross-sectional area as that of the corresponding ground electrode.

The matching layer 150 may be composed of a plurality of layers of one or two layers, for example, two-

layer structures

151 and 152 as shown in FIG. 2. The reason why the matching layer 150 is formed of a plurality of layers is that the difference in acoustic impedance between the active element 130 and the human tissue under test is relatively large, so that the matching layer having the required characteristics is formed as a single material layer. Because it is difficult to form. The acoustic lens 160 may be coupled to the matching layer 150, and ultrasonic waves may be connected to the inspected object through the acoustic lens 160.

3 is a structural diagram schematically illustrating the configuration of an ultrasonic transducer including an active device in which an even number of layers are stacked according to an embodiment of the present invention.

Referring to FIG. 3, although the active element 230 shows an ultrasonic transducer 1b including an even layer including a first layer 231 and a second layer 232, the number of even layers is limited to two. It doesn't work. Hereinafter, for convenience of description, the active element 230 will be described below with reference to the ultrasonic transducer 1b including the first layer 231 and the second layer 232, as shown in FIG. 3.

Ultrasonic transducers with even-numbered active elements are not easily wired. This occurs when the flexible printed circuit board coupled with the active element is composed of a substrate layer and a metal layer. However, since the flexible printed circuit board 220 according to an embodiment is a single metal layer, an even-numbered ultrasonic transducer may be easily designed.

Referring to FIG. 3, the first ground layer 241 is coupled to the front surface of the backing material 210, and the first layer 231 of the active device 230 is coupled to the front surface of the first ground layer 241. The flexible printed circuit board 220 is coupled to the front surface of the first layer 231. The second layer 232 is coupled to the front surface of the flexible printed circuit board 220. The pair of active elements, the first layer 231 and the second layer 232, are coupled to each surface of the flexible printed circuit board 220 with the flexible printed circuit board 220 therebetween. The second ground layer 242 is coupled to the front surface of the second layer 232 of the active element 230, and the matching layer 250 is coupled to the front surface of the second ground layer 242. The first ground layer 241 and the second ground layer 242 are combined to be referred to as the ground layer 240.

In FIG. 3, the flexible printed circuit board 220 is positioned between the first layer 231 and the second layer 232 of the active element 230, and the first ground layer 241 is formed on the front surface of the first layer 231. Although the second ground layer 242 is positioned on the front surface of the second layer 232, the position may vary depending on the polling direction of the layer constituting the active device. For example, a ground layer may be formed in place of the flexible printed circuit board 220, and a flexible printed circuit board may be positioned in place of the first ground layer 241 and the second ground layer 242, respectively.

Hereinafter, each component will be described. Since the main description has been described above with reference to FIG. 2, the description will be mainly given of differences.

The backing material 210 may be configured to have sound attenuation characteristics, which are excellent sound absorption characteristics. The backing material 210 may be coupled to the first ground layer 241 located at the front surface.

The first ground layer 241 is disposed on the front surface of the backing material 210, and the front surface of the first ground layer 241 is coupled to the first layer 231 of the active device 230. The first ground layer 241 according to an embodiment may be formed of a conductive metal flake, and may have ground electrodes bonded to one surface of the corresponding active element 230 in a form separated from each other to correspond to the active element 230. have. The ground electrode may be made of a flake of conductive metal such as copper, gold, silver, or the like. In addition, the ground electrode may have a cross-sectional area equal to the cross-sectional area of the first layer 231 of the corresponding active element and have a predetermined thickness.

The first layer 231 of the active device 230 has a rear surface coupled with the first ground layer 241 and a front surface coupled with the flexible printed circuit board 220. The flexible printed circuit board 220 is formed between the first layer 231 and the second layer 232 of the active element 230 to supply an electrical signal to the active element 230. Flexible printed circuit board 220 is a single metal layer. The metal layer may be, for example, a copper (Cu) layer. The shape, arrangement pattern, thickness, and width of the electrode formed on the metal layer may vary depending on the type or characteristics of the active element 230 and / or the ultrasonic transducer 1b including the same, and thus, the present embodiment is not limited thereto. There is no

The flexible printed circuit board 220 according to an embodiment is not formed of the metal layer and the substrate layer, but only the metal layer. Therefore, the acoustic characteristics due to the difference in acoustic impedance between the metal layer and the substrate layer can be improved.

When the flexible printed circuit board is formed of a metal layer and a substrate layer, the substrate layer must be removed by etching in order to directly bond the metal layer to the active device. However, the flexible printed circuit board 220 according to an exemplary embodiment does not use a method of removing a substrate layer through etching, but rather, manufactures a metal layer, for example, copper foil itself using a flexible printed circuit board. Accordingly, no additional process such as the etching process described above is required, and the transducer can be manufactured simply.

The active device 230 according to an embodiment is composed of an even layer including a first layer 231 and a second layer 232. In the active device 230, as illustrated in FIG. 3, a first layer 231 is positioned between the first ground layer 241 and the flexible printed circuit board 220, and the second layer 232 is a flexible printed circuit board. It may be disposed to be stacked with the 220 and the second ground layer 242 interposed therebetween. Since the active element 230 has a stacked structure, the impedance can be reduced and capacitance can be increased as compared with a structure having a single layer of active elements.

The second ground layer 242 is coupled to the entire surface of the second layer 232 of the active element 230, and serves as a ground electrode as a conductive material. Like the flexible printed circuit board 220, the second ground layer 242 is formed of a single conductive layer. The second ground layer 242 may be formed of a conductive metal flake, and may have ground electrodes bonded to one surface of the corresponding active element 230 in a form separated from each other to correspond to the active element 230. The flakes of the conductive metal may be made of raw materials such as copper, gold, silver, and the like. The ground electrode may have a cross-sectional area equal to the cross-sectional area of the second layer 232 of the corresponding active element and have a predetermined thickness.

The matching layer 250 may be positioned in front of the second layer 232 of the active device 230 and may be coupled to the second ground layer 242. The matching layer 250 serves as a buffer for reducing problems such as image distortion due to a sudden change in acoustic impedance between the active element 230 and the object under test. The matching layer 250 may be composed of one, two or more layers, and two-

layer structures

251 and 252 are widely used as shown in FIG. 3. An acoustic lens 260 may be coupled to the matching layer 250, and ultrasonic waves may be connected to the object through the acoustic lens 260.

4 is a structural diagram of a general flexible printed circuit board composed of a metal layer, a substrate layer, and a metal layer.

Referring to FIG. 4, a typical flexible printed circuit board 420 may be formed of a

metal layer

422, 423, for example, copper, above and below one substrate layer 421, for example, a polyimide (PI) layer. Cu) layer is arrange | positioned. In addition, a cover layer 424 may be stacked on upper and lower surfaces. In the case of the multilayer flexible printed circuit board made of the above-described metal layer (Cu) 422-substrate layer (PI) 421-metal layer (Cu) 423, the acoustic impedance of copper (Cu) and polyimide (PI) Differences adversely affect acoustic performance.

In addition, the multilayer flexible printed circuit board 420 must remove the substrate layer 421 through etching in order to directly couple the metal layers 422 and 423 to the active device. At this time, the active area 40 coupled to correspond to the shape of the active element should be removed by etching.

5 is a structural diagram of a flexible printed circuit board as a metal layer according to an embodiment of the present invention.

Referring to FIG. 5, the flexible printed circuit board 520 according to an embodiment is a single metal layer 521. It does not have a metal layer-substrate layer-metal layer structure like the flexible printed circuit board described above with reference to FIG. 4, but only a metal layer 521, for example, a copper layer. A cover layer 524 may be stacked on the upper and lower surfaces of the metal layer 521. As the flexible printed circuit board 520 is a single metal layer, acoustic characteristics may be improved due to a difference in acoustic impedance between the metal layer and the substrate layer.

Furthermore, the flexible printed circuit board 520 according to the exemplary embodiment does not use a method of removing the substrate layer through etching or the like, but instead of the metal layer 521, for example, copper foil, the flexible printed circuit board may be used. As manufactured at 520, an additional process such as the etching process described above with reference to FIG. 4 is unnecessary, and the ultrasonic transducer may be simply manufactured. At this time, the activation region 50 that is coupled corresponding to the shape of the active element may be directly coupled with the active element without a removal process such as etching.

6 is a flowchart illustrating a method of manufacturing a flexible printed circuit board of an ultrasonic transducer according to an embodiment of the present invention.

Referring to FIG. 6, first, a raw material that is a conductor is cut into a substrate (600). The raw material may be a metal such as copper (Cu), which is a conductor having excellent electrical conductivity, but is not limited thereto. However, the substrate here is a conductor layer, not a polyimide layer made of polyimide.

Subsequently, the carrier may be adhered or thermally compressed 610 on one surface of the cut substrate, and a circuit pattern may be formed on the entire surface of the substrate, for example, copper foil, adhered or thermally compressed (620). The circuit pattern forming step 620 according to an embodiment may include exposure, development, corrosion, peeling, and drying. For example, a portion of the substrate is exposed and developed to form a circuit of the desired pattern. The substrate, which is a metal layer, is composed of an active area where an active element is to be bonded, and a trace for transmitting and receiving signals, which are coupled to the active element to transmit and receive signals between the active element and the system. .

Since the flexible printed circuit board according to the exemplary embodiment is a single metal layer, for example, a single metal layer, the flexible printed circuit board is required to directly bond the metal layer and the active element to the multilayer flexible printed circuit board structure including the metal layer and the substrate layer. There is no need for an etching process. For example, a process of removing a portion of the metal layer to be bonded to the active element and a portion thereof except for the portion connected to the active element and removing a portion of the substrate layer to correspond to the shape of the active element is not necessary.

Subsequently, a cover layer is attached to the front and rear surfaces of the substrate (630). In this case, the protective layer may cover the remaining portion of the flexible printed circuit board, which is a metal layer, except for the active region to which the active element is attached. Accordingly, the metal layer can be prevented from being exposed to the outside and the metal layer can be protected. Furthermore, the method may include surface treating the front and rear surfaces of the metal layer exposed to the outside with the surface treatment layer. The completed flexible printed circuit board may be coupled to an active device. In this case, the active elements may be stacked on the front surface of the flexible printed circuit board, thereby reducing the impedance between the active elements and increasing the capacitance.

7 is a flowchart illustrating a method of manufacturing an ultrasonic transducer according to an embodiment of the present invention.

Referring to FIG. 7, the manufacturing method of the flexible printed circuit board is new as described above with reference to FIG. 6, but the manufacturing method of the array is the same as in the related art. For example, to fabricate an array, after cleaning 700 the elements, stacking 710 the cleaned elements, dividing the elements 720, and filling 730 with a kerf. In operation 740, an acoustic lens is attached.

On the other hand, with reference to Figures 8 to 15, will be described the difference between the performance of the ultrasonic transducer and the general ultrasonic transducer according to an embodiment of the present invention.

8 is a graph comparing voltage changes over time of an ultrasonic transducer and a general ultrasonic transducer according to an exemplary embodiment of the present invention. 8 shows the result of analysis using a simulation tool such as PZflex.

The upper graph shows the change of voltage with time of a typical ultrasonic transducer in which the active element is a single layer, and the middle graph shows the active element in multiple layers, This is a graph showing the voltage change over time of an ultrasonic transducer including a general flexible printed circuit board having a conductive layer formed thereon, and the graph below shows a flexible printed circuit board having a plurality of layers of active elements and a single metal layer. It shows the voltage change with time of the ultrasonic transducer of the present embodiment including. It can be seen from the graph comparison shown in FIG. 8 that the ultrasonic transducer of the present embodiment has a larger voltage change at the same time.

9 is a graph comparing the change in the normal size according to the frequency of the ultrasonic transducer and the general ultrasonic transducer according to an embodiment of the present invention. 9 shows the results of analysis using a simulation tool such as PZflex.

Referring to FIG. 9, a change in normalized magnitude according to a frequency of a general ultrasonic transducer in which an active element is made of a single layer, and the active element is made of a plurality of layers, and a conductive layer on the substrate layer The ultrasonic transducer according to the present embodiment includes a change in a normal size according to a frequency of a general ultrasonic transducer including the flexible printed circuit board formed thereon, and an active element including a flexible printed circuit board having a plurality of layers and a single metal layer. Compare the change in normal magnitude with frequency.

From the graph comparison shown in Figure 9, it can be seen that in the case of the ultrasonic transducer of the present embodiment, the normal size is larger in a wider range. In the case of the ultrasonic transducer of the present embodiment, the bandwidth and the fractional bandwidth are widened, and the sensitivity is improved.

10 is a graph showing an effect of improving impedance mismatch between a general ultrasonic transducer and a cable of an ultrasonic transducer according to an embodiment of the present invention. In detail, FIG. 10 shows the change in intensity at the array transducer level.

As shown in FIG. 10, it can be seen that the impedance of the ultrasonic transducer of the present embodiment has a smaller value than that of the general ultrasonic transducer in a small frequency region, and the impedance mismatch between the transducer and the cable is improved.

11 and 12 are graphs showing the effect of improving the acoustic characteristics of the ultrasonic transducer and the general ultrasonic transducer according to an embodiment of the present invention.

In detail, FIG. 11 compares the magnitude of the voltage versus time of a conventional ultrasonic transducer having a single layer active element and an ultrasonic transducer of the present invention including an active element loaded with multiple layers. It is a graph. As shown in Figure 11, it can be seen that the ultrasonic transducer of the present embodiment has a larger voltage change in the same time zone.

FIG. 12 is a graph comparing normalized magnitudes to frequencies of a general ultrasonic transducer having a single layer active element and an ultrasonic transducer of the present invention including an active element loaded with a plurality of layers. . As shown in FIG. 12, in the case of the ultrasonic transducer of the present embodiment, it can be seen that the normal size is large in a wider range. In the case of the ultrasonic transducer of the present embodiment, the bandwidth and the fractional bandwidth are widened, and the sensitivity is improved.

So far, the present invention has been described with reference to the embodiments. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

Claims

An active element composed of a plurality of layers; And

A flexible printed circuit board which is a single metal layer which is directly coupled to one surface of at least one layer constituting the active element to supply an electrical signal;

Ultrasonic transducer comprising a.
The flexible printed circuit board of claim 1, wherein the flexible printed circuit board

An ultrasonic transducer, characterized in that it is a single conductive metal flake having a circuit pattern formed thereon.
The method of claim 1,

The flexible printed circuit board is bonded to one surface of at least one layer of the active device, and the active region of the flexible printed circuit board, which is bonded to one surface of the active device, is formed of a conductive material corresponding to the formation of the one surface. Ultrasonic transducer.
The method of claim 1, wherein the ultrasonic transducer is

A ground layer, which is a single metal layer electrically connected to the active element;

Ultrasonic transducer, characterized in that it further comprises.
An active device in which an even layer including a first layer and a second layer is stacked;

A backing material positioned on a rear surface of the first layer of the active element to block or attenuate ultrasonic waves generated by the active element and propagated to the rear surface;

A matching layer positioned on a front surface of the second layer and matching an acoustic impedance of ultrasonic waves generated by the active element and propagated to the front surface; And

A flexible printed circuit board positioned between a first layer and a second layer of the active element and a single metal layer electrically connected to the active element;

Ultrasonic transducer comprising a.
The flexible printed circuit board of claim 5, wherein the flexible printed circuit board

An ultrasonic transducer, characterized in that it is a single conductive metal flake having a circuit pattern formed thereon.
The method of claim 5, wherein

The flexible printed circuit board is bonded to one surface of the first layer and the second layer of the active element, respectively, and the activation area of the flexible printed circuit board is bonded to the one surface of the first layer and the second layer of the active element. Ultrasonic transducer, characterized in that consisting of a conductive material corresponding to the formation of.
The method of claim 5, wherein the ultrasonic transducer is

A first ground layer disposed between the first layer of the active element and the backing material, the first ground layer being a single metal layer electrically connected to the active element; And

A second ground layer disposed between the second layer of the active element and the matching layer, the second ground layer being a single metal layer electrically connected to the active element;

Ultrasonic transducer, characterized in that it further comprises.
The method of claim 5, wherein the active element

Ultrasonic transducer, characterized in that a plurality of piezoelectric elements.
The method of claim 5, wherein the matching layer

Ultrasonic transducer, characterized in that consisting of a plurality of layers.
An active element having an odd layer including a first layer, a second layer, and a third layer stacked thereon;

A backing material positioned on a rear surface of the first layer of the active element to block or attenuate ultrasonic waves generated by the active element and propagated to the rear surface;

A matching layer positioned on a front surface of the third layer to match acoustic impedance of ultrasonic waves generated by the active element and propagated to the front surface;

A first electrode part disposed between the first layer of the active element and the backing material and being a single metal layer electrically connected to the active element; And

A second electrode part disposed between the third layer and the matching layer of the active element and being a single metal layer electrically connected to the active element;

Ultrasonic transducer comprising a.
The method of claim 11,

And the first electrode part is a flexible printed circuit board and the second electrode part is a ground layer.
The method of claim 11,

And the first electrode part is a ground layer, and the second electrode part is a flexible printed circuit board.
The method of claim 11, wherein the first electrode portion and the second electrode portion

An ultrasonic transducer, characterized in that it is a single conductive metal flake having a circuit pattern formed thereon.
The method of claim 11,

The first electrode portion is adhered to one surface of at least one layer of the active element, the activation region of the first electrode portion adhered to one surface of the active element is made of a conductive material corresponding to the formation of the one surface,

Wherein the second electrode portion adheres to one surface of at least one layer of the active element, and the activation region of the second electrode portion adheres to one surface of the active element is made of a conductive material corresponding to the formation of the one surface. Ultrasonic transducer.
The method of claim 11, wherein the active element

Ultrasonic transducer, characterized in that a plurality of piezoelectric elements.
The method of claim 11, wherein the matching layer

Ultrasonic transducer, characterized in that consisting of a plurality of layers.
Forming a flexible printed circuit board; And

Coupling the formed flexible printed circuit board to an active device composed of a plurality of layers; Including;

Forming the flexible printed circuit board

Cutting a single layer of raw material into a substrate form;

Pressing or thermocompressing the carrier to the cut substrate;

Forming a circuit pattern on the front surface of the tightly or thermocompressed substrate; And

Attaching a protective layer to an upper surface of the substrate except for a pattern in which the active elements are stacked;

Ultrasonic transducer manufacturing method comprising a.
The flexible printed circuit board of claim 18, wherein the flexible printed circuit board

Ultrasonic transducer manufacturing method characterized in that the circuit pattern is formed of a single conductive metal flake.
The method of claim 18, wherein the ultrasonic transducer manufacturing method

Forming a ground layer that is a single metal layer; And

Coupling the formed ground layer to the active device;

Ultrasonic transducer manufacturing method comprising a further.