KR20160064514A - Multi-layered ultrasonic transducer and method for manufacture thereof - Google Patents

Multi-layered ultrasonic transducer and method for manufacture thereof Download PDF

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Publication number
KR20160064514A
KR20160064514A KR1020140168200A KR20140168200A KR20160064514A KR 20160064514 A KR20160064514 A KR 20160064514A KR 1020140168200 A KR1020140168200 A KR 1020140168200A KR 20140168200 A KR20140168200 A KR 20140168200A KR 20160064514 A KR20160064514 A KR 20160064514A
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KR
South Korea
Prior art keywords
layer
active element
ultrasonic transducer
circuit board
printed circuit
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KR1020140168200A
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Korean (ko)
Inventor
신은희
김희원
이상웅
이재원
김성학
Original Assignee
알피니언메디칼시스템 주식회사
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Priority to KR1020140168200A priority Critical patent/KR20160064514A/en
Publication of KR20160064514A publication Critical patent/KR20160064514A/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/005—Piezoelectric transducers; Electrostrictive transducers using a piezoelectric polymer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor

Abstract

A multi-layer ultrasonic transducer and a method of manufacturing the same are disclosed. A multi-layer ultrasonic transducer according to an embodiment of the present invention includes: an active element composed of a plurality of layers; a flexible printed circuit which is a single metal layer that directly couples to one surface of at least one layer constituting the active element to supply an electric signal; Circuit board.

Description

[0001] The present invention relates to a multi-layer ultrasonic transducer and a manufacturing method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an ultrasonic transducer for acquiring image information inside a subject using ultrasound.

An ultrasound diagnostic apparatus is an apparatus for imaging an internal tissue of a subject with a reflected ultrasound signal by emitting an ultrasound signal to the subject. The ultrasound diagnostic apparatus transmits ultrasound signals to a diagnostic region of an object to be examined and then receives ultrasound signals reflected from boundaries of tissues inside the object having different acoustic impedances to acquire image information of the diagnostic region .

The ultrasonic diagnostic apparatus includes an ultrasonic transducer for transmitting an ultrasonic signal to a subject and receiving an ultrasonic signal reflected from the subject. Ultrasonic transducers largely include an active element, a matching layer, and a backer. Recently, as the manufacturing technology of ultrasonic transducer has been developed, the pitch of the active element is decreasing and the number of it is increasing to increase the lateral resolution.

According to an embodiment, there is proposed a multi-layer ultrasonic transducer having improved acoustic performance and impedance mismatch between a cable and a manufacturing process, and a manufacturing method thereof.

The 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 which directly couples to one surface of at least one layer constituting the active element to supply an electric 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 element and the active area of the flexible printed circuit board bonded to one surface of the active element 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.

According to another aspect of the present invention, there is provided an ultrasonic transducer including: an active element having an even number of layers including a first layer and a second layer stacked; A matching layer which is positioned on the front surface of the second layer and matches the acoustic impedance of the ultrasonic wave generated in the active element and propagated to the front surface of the active layer, And a flexible printed circuit board positioned between the first layer and the second layer and being a single metal layer electrically connected to the active element.

The flexible printed circuit board may be a single conductive metal flake having a circuit pattern formed thereon. Wherein the flexible printed circuit board adheres to one surface of the first layer and the second layer of the active element and the active area of the flexible printed circuit board that adheres to one surface of the first layer and the second layer of the active element, May be formed of a conductive material corresponding to the formation of the conductive layer.

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

According to another aspect of the present invention, there is provided an ultrasonic transducer including: an active element having an odd number of layers including a first layer, a second layer and a third layer stacked; A matching layer which is positioned on the front surface of the third layer and matches the acoustic impedance of ultrasonic waves generated in the active element and propagated to the front surface, A first electrode portion which is located between the first layer of the active element and the backing material and is a single metal layer electrically connected to the active element; and a second electrode portion located between the third layer of the active element and the matching layer, And a second electrode part which is a single metal layer electrically connected to the first electrode part.

The first electrode portion may be a flexible printed circuit board, and the second electrode portion may be a ground layer. Or the first electrode portion may be a ground layer, and the second electrode portion 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. Wherein the first electrode portion is bonded to one surface of at least one layer of the active element and the activation region of the first electrode portion bonded to one surface of the active element is made of a conductive material corresponding to the formation of the one surface, The electrode portion may be bonded to one surface of at least one layer of the active element and the activation region of the second electrode portion 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.

According to another aspect of the present invention, there is provided a method of manufacturing an ultrasonic transducer, comprising the steps of: forming a flexible printed circuit board; and bonding the formed flexible printed circuit board to an active element composed of a plurality of layers, The step of forming the circuit board includes the steps of cutting the raw material of a single layer into a substrate form, adhering or thermocompressing the carrier to the cut substrate, forming a circuit pattern on the entire surface of the adhered or thermocompressed substrate And attaching a protective layer on the upper surface of the substrate except 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 that is a single metal layer, and bonding the formed ground layer to the active element.

According to one embodiment, as the active element provides an ultrasonic transducer composed of multiple layers, the capacitance increases and the electrical impedance decreases, thereby improving the mismatch between the cables.

In order to electrically connect a multi-layer active element, a double side FCCL having a substrate layer and a substrate layer and a lower metal layer is used, or a substrate layer and a substrate layer, And a flexible printed circuit board (single side FCCL) having a metal layer on one side thereof. However, in the former case, there is a large difference in impedance between the active elements, which may lead to loss of ultrasonic waves. In the latter case, a process of etching the substrate layer to bond 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, And the manufacturing time can be shortened.

Furthermore, in manufacturing an ultrasonic transducer composed of a plurality of active element layers, an ultrasonic transducer composed of an even number of active elements, which is difficult to manufacture as well as an ultrasonic transducer composed of an odd number of active elements, is easy and simple .

1 is a structural view illustrating an ultrasonic transducer constituted by a plurality of elements according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a configuration of an ultrasonic transducer including an active element in which an odd number of layers are stacked according to an embodiment of the present invention. FIG.
FIG. 3 is a schematic diagram illustrating a configuration of an ultrasonic transducer including an active element having an even number of layers stacked according to an embodiment of the present invention. FIG.
4 is a structural view of a general flexible printed circuit board composed of a metal layer, a substrate layer and a metal layer,
5 is a structural view of a flexible printed circuit board which is 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.
FIG. 7 is a flowchart illustrating a method of manufacturing an ultrasonic transducer according to an embodiment of the present invention. FIG.
FIG. 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,
FIG. 9 is a graph showing changes in normal size according to frequencies of an ultrasonic transducer and a general ultrasonic transducer according to an embodiment of the present invention,
10 is a graph showing an effect of improving the 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 sizes of the ultrasonic transducers of the present invention, including a general ultrasonic transducer having a single layer of active elements and an active element having a plurality of layers,
12 is a graph comparing voltage magnitudes with respect to a frequency of an ultrasonic transducer of the present invention including a general ultrasonic transducer having a single layer of active elements and an active element having a plurality of layers mounted thereon.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention of the user, the operator, or the custom. Therefore, the definition should be based on the contents throughout this specification.

1 is a structural view illustrating an ultrasonic transducer constituted by a plurality of elements according to an embodiment of the present invention.

1, the direction in which the array of the ultrasonic transducer 1 is arranged is referred to as an azimuth direction, the direction in which a beam signal travels is referred to as an axial direction, The orthogonal direction is called the elevation direction.

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

However, as the number of elements 12 of the array increases within the same aperture size, the capacitance of the element 12 becomes lower and the impedance becomes higher, resulting in impedance mismatching with the cable mismatch occurs. In particular, impedance mismatch is more pronounced for low frequency array transducers. Accordingly, the present invention proposes a multi-active layered structure in which devices are stacked in a multi-layer. When the device is stacked with N layers, as shown in Equation 1, the capacitance C increases to N 2 , and the electrical impedance decreases to N 2 , thereby improving mismatch between the cables.

Figure pat00001
(One)

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

FIG. 2 is a schematic diagram showing a configuration of an ultrasonic transducer including an active element in which an odd number of layers are stacked according to an embodiment of the present invention. Referring to FIG.

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

In the present specification, when it is assumed that a layer of a first material is formed on a layer of a second material, it is possible that the layer of the first material is formed directly on the layer of the second material, It is to be understood that all of the third material layers are interposed between the first material layer and the second material layer.

2 shows an ultrasonic transducer la in which an active element 130 is stacked with an odd-numbered layer, for example a first layer 131, a second layer 132 and a third layer 133 . However, this is for facilitating understanding of the present invention, and the number of the odd-numbered layers is not limited to three. Hereinafter, for convenience of description, the ultrasonic transducer 1a in which three layers are stacked as shown in FIG. 2 will be described below. If the active element is an odd-numbered layer, the electrical connection is easy.

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

The ultrasonic transducer 1a may be an array transducer in a linear or matrix form. 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 the ultrasonic transducer 1a, A ground layer 140 is coupled to the front surface of the active element 130 and a matching layer 150 is coupled to the entire surface of the ground layer 140. On the front surface of the matching layer 150, an acoustic lens 160 is formed.

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. However, ≪ / RTI > For example, the flexible printed circuit board 120 may be located on the rear surface of the matching layer 150, and the ground layer 140 may be positioned on the front surface of the backing material 110.

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

The backing material 110 is configured such that the acoustic impedance matches the active element 130 well. The backing material 110 can be configured to have an acoustic attenuation characteristic, which is a superior sound absorbing characteristic. The backing material 110 having excellent sound absorption characteristics suppresses the free vibration of the active element 130 formed on the front surface so as to reduce the pulse width of the ultrasonic wave as well as to cause the ultrasonic waves to propagate to the back surface unnecessarily Thereby effectively preventing image distortion. The backing material 110 may be formed of one or a plurality of layers using a material having excellent sound absorption properties. The backing material 110 is coupled to the flexible printed circuit board 120 positioned on the front side and can exchange electrical signals with the active elements 130 positioned on the front side of the flexible printed circuit board 120.

The flexible printed circuit board 120 is coupled to the back surface of the first layer 131 of the active element 130 to provide an electrical signal to the active element 130. The 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, width, etc. of the electrodes formed on the metal layer may vary depending on the types and characteristics of the active element 130 and / or the ultrasonic transducer 1a including the active element 130.

A conventional flexible printed circuit board is manufactured by forming a metal layer, for example, a copper (Cu) layer on one substrate layer, for example, a polyimide (PI) layer to form a substrate layer Or a multilayer of a metal layer (Cu) - a substrate layer (PI) - a metal layer (Cu), for example, a metal layer such as a copper layer formed on the front and rear surfaces of a substrate layer, Type flexible printed circuit board structure. The above-described multilayer flexible printed circuit board structure is as shown in FIG. 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 impedances of the two materials are good for acoustic performance .

The flexible printed circuit board 120 according to an embodiment of the present invention is a single metal layer. It is not composed of a substrate layer and a metal layer, but is made of only a metal layer. The metal layer directly couples to one surface of the active element 130 to provide an electrical signal. As the flexible printed circuit board 120 is a single metal layer, it is possible to improve the 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 through etching in order to bond the metal layer directly to the active element. However, the flexible printed circuit board 120 according to an embodiment does not use a method of removing a substrate layer through etching or the like, but rather a metal layer, for example, a copper foil itself is manufactured as a flexible printed circuit board Accordingly, no additional process such as the etching process described above is required, and the transducer can be simply manufactured.

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

The active element 130 generates an ultrasonic signal when energy is applied by applying a voltage to the flexible printed circuit board 120 and the ground layer 140 located at both ends. The ultrasound signal generated by the active device 130 according to an exemplary embodiment may have various frequencies. For example, the generated ultrasonic signal can generate a signal of a higher frequency as well as a frequency of 17 MHz or lower which is currently used.

The type of the active element 130 may vary depending on the type of the ultrasonic transducer 1a, and may be a piezoelectric element. A piezoelectric element is a part having a property of generating a voltage when a mechanical pressure is applied through a piezoelectric effect and a mechanical deformation when a voltage is applied. There is no particular limitation on the shape or arrangement pattern of the piezoelectric elements. For example, the piezoelectric elements correspond to the electrodes of the flexible printed circuit board 120 and are arranged in mutually separated patterns. Piezoelectric elements include piezoelectric ceramics such as lead zirconate titanate (PZT), single crystals, composite piezoelectric materials obtained by combining these materials with polymer materials, or polymer materials represented by polyvinylidene fluoride (PVDF) A piezoelectric substance or the like. Further, when fabricated with a laminated structure, the same piezoelectric elements may be laminated, but other piezoelectric elements may be laminated by PZT, piezoelectric ceramics, single crystal or the like.

The ground layer 140 acts as a ground electrode with a conductive material. The ground layer 140 is in contact with one surface of the third layer 133 of the active element 130. The ground layer 140 is also made of a single metal layer like the flexible printed circuit board 120. The single metal layer may be formed of a conductive metal foil and may have ground electrodes that are bonded to one surface of the active element 130 in a mutually separated form corresponding 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 corresponding active element 130 and have a predetermined thickness.

The matching layer 150 is located on the front surface of the third layer 133 of the active device 130 and can be coupled to the ground layer 140. The matching layer 150 appropriately matches the acoustic impedance of the active element 130 with the acoustic impedance of the active element 130 so that the ultrasound generated in the active element 130 is transmitted to the subject and / Thereby reducing the loss of ultrasonic waves (echosound waves). The matching layer 150 can serve as a buffer to reduce problems such as image distortion due to a sudden change in acoustic impedance between the active element 130 and the test object.

The matching layer 150 is formed in a sheet shape using a predetermined material to have a predetermined thickness and then formed into a desired thickness and / or shape through a process such as machining. Then, Layer 140 may be formed. 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 the respective front surfaces of the ground electrodes in mutually separated shapes. The matching layer 150 may have a cross-sectional area equal to the cross-sectional area of the corresponding ground electrode.

The matching layer 150 may be comprised of one or more layers, for example a two-layer structure 151, 152 as shown in FIG. The reason why the matching layer 150 is composed of a plurality of layers is that since the acoustic impedance difference between the active element 130 and the human body under test is relatively large, Is difficult to form. The acoustic lens 160 may be coupled to the matching layer 150, and ultrasound waves may be connected to the subject through the acoustic lens 160.

FIG. 3 is a schematic diagram illustrating a configuration of an ultrasonic transducer including an active element having an even number of layers stacked according to an embodiment of the present invention. Referring to FIG.

3, the active element 230 shows an ultrasonic transducer 1b composed of even layers including a first layer 231 and a second layer 232. However, the number of even layers is limited to two It does not. 3, the active element 230 will be described below with reference to an ultrasonic transducer 1b composed of a first layer 231 and a second layer 232. [

An ultrasonic transducer composed of even-numbered active elements is not easy to be electrically connected. This occurs when the flexible printed circuit board that is 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 one embodiment is a single metal layer, it is possible to easily design an even-numbered layer ultrasonic transducer.

Referring to FIG. 3, a first ground layer 241 is coupled to a front surface of a backing material 210, a first layer 231 of an active device 230 is coupled to a front surface of a 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 first layer 231 and the second layer 232, which are a pair of active elements, are coupled to the respective sides of the flexible printed circuit board 220 with the flexible printed circuit board 220 interposed therebetween. A second ground layer 242 couples to the front surface of the second layer 232 of the active element 230 and a matching layer 250 couples to the front surface of the second ground layer 242. The first ground layer 241 and the second ground layer 242 are combined to form a ground layer 240.

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 disposed between the front surface of the first layer 231 And the second ground layer 242 is located on the front surface of the second layer 232. However, the position of the second ground layer 242 may be changed according to the poling direction of the layer constituting the active device. For example, a ground layer may be formed instead of the flexible printed circuit board 220, and a flexible printed circuit board may be disposed instead 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 given above with reference to FIG. 2, differences will be mainly described.

The backing material 210 can be configured to have an acoustic attenuation characteristic, which is a superior sound absorbing characteristic. The backing material 210 may be bonded to the first ground layer 241 located on 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 element 230. The first ground layer 241 according to an embodiment is formed of a conductive metal foil and has ground electrodes connected to one surface of a corresponding active element 230 in a mutually separated form corresponding to the active element 230 have. The ground electrode may be formed of a thin film of a 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 is coupled to the first ground layer 241 at the rear side and the front side is coupled to the flexible printed circuit board 220 at the front side. The flexible printed circuit board 220 is formed between the first layer 231 and the second layer 232 of the active element 230 and supplies an electrical signal to the active element 230. The 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, width, etc. of the electrodes formed on the metal layer may vary depending on the types and characteristics of the active element 230 and / or the ultrasonic transducer 1b including the active element 230, There is no.

The flexible printed circuit board 220 according to one embodiment does not consist of a metal layer and a substrate layer, but is made of only a 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 composed of a metal layer and a substrate layer, the substrate layer must be removed through etching in order to bond the metal layer directly to the active element. However, the flexible printed circuit board 220 according to an exemplary embodiment does not use a method of removing a substrate layer through etching or the like, but rather a metal layer, for example, a copper foil itself is manufactured as a flexible printed circuit board Accordingly, no additional process such as the above-described etching process is required, and the transducer can be simply manufactured.

The active element 230 according to one embodiment is composed of an even layer including a first layer 231 and a second layer 232. The active element 230 is positioned between the first ground layer 241 and the flexible printed circuit board 220 and the second layer 232 is positioned between the flexible printed circuit board 220 and the flexible printed circuit board 220, The first ground layer 220 and the second ground layer 242 may be stacked. Since the active element 230 has a laminated structure, the impedance can be reduced and the capacitance can be increased compared with a structure having a single active element.

The second ground layer 242 is bonded to the entire surface of the second layer 232 of the active element 230 and functions as a ground electrode with a conductive material. The second ground layer 242 is also composed of a single conductive layer like the flexible printed circuit board 220. The second ground layer 242 may be formed of a conductive metal foil and may have ground electrodes connected to one surface of the corresponding active element 230 in a mutually separated form corresponding to the active element 230. The thin 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 may have a shape having a constant thickness.

The matching layer 250 is located on the front surface of the second layer 232 of the active element 230 and can be coupled to the second ground layer 242. The matching layer 250 serves as a buffer to reduce problems such as image distortion due to a sudden change in acoustic impedance between the active element 230 and the subject. The matching layer 250 may be composed of one or more layers of two or more layers, as shown in FIG. 3, the two-layer structures 251 and 252 are widely used. The matching layer 250 can be coupled to the acoustic lens 260, and the ultrasonic wave can be connected to the subject through the acoustic lens 260.

4 is a structural view of a general flexible printed circuit board composed of a metal layer-substrate layer-metal layer.

4, a typical flexible printed circuit board 420 includes a substrate layer 421, for example, a metal layer 422, 423 over a polyimide (PI) layer, for example, a copper (Cu) Cu) layer is disposed. A cover layer 424 may be laminated on the upper and lower surfaces. In the case of a multilayer flexible printed circuit board composed of the above-described metal layer (Cu) 422-substrate layer (PI) 421-metal layer (Cu) 423, the acoustic impedance of copper (Cu) and polyimide The difference will adversely affect the 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 with the active elements. At this time, an active area 40 corresponding to the shape of the active device to be coupled must be removed through etching.

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

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

In addition, the flexible printed circuit board 520 according to an embodiment does not use a method of removing the substrate layer through etching or the like, but uses a metal layer 521, for example, a copper foil itself as a flexible printed circuit board (520), an additional process such as the etching process described above with reference to FIG. 4 is not necessary, and the ultrasonic transducer can be simply manufactured. At this time, the active region 50 to be coupled with the shape of the active element can be directly coupled to the active element without removing processes 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, the conductive raw material is cut into a substrate form (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 is not a polyimide layer of polyimide generally used but a conductor layer.

Subsequently, the carrier is adhered or thermally pressed (610) to one side of the cut substrate, and a circuit pattern is formed on the entire surface of the adhered or thermally bonded substrate, for example, a copper foil (620). The circuit pattern forming step 620 according to an exemplary embodiment may include steps such as exposure, development, erosion, peeling, and drying. For example, a portion of the substrate is exposed and developed to form a circuit of a desired pattern. The substrate, which is a metal layer, is composed of an active area, to which the active elements are adhered, and a trace, which transmits and receives signals. The trace is coupled to the active elements to transmit and receive signals between the active elements and the system .

Since the flexible printed circuit board according to one embodiment is a single metal layer, for example, a single metal layer, it is required to directly adhere the metal layer and the active element to a multilayer flexible printed circuit board structure composed of a metal layer and a substrate layer An etching process is not necessary. For example, there is no need to remove a portion of the metal layer to be adhered to the active element except for the portion to be adhered thereto, and to remove a portion of the substrate layer corresponding to the shape of the active element.

Next, a cover layer is attached to the front and rear surfaces of the substrate (630). At this time, the remaining portion of the flexible printed circuit board, which is a metal layer, except for the active region where the active element is attached, may be covered with a protective layer. Thus, the metal layer can be prevented from being exposed to the outside, and the metal layer can be protected. Further, it may include the step of surface-treating the front surface and the rear surface of the metal layer exposed to the outside with the surface treatment layer. The completed flexible printed circuit board can then be coupled to the active element. At this time, the active elements can be stacked on the entire surface of the flexible printed circuit board, thereby reducing the impedance between the active elements and increasing the coaxiality.

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

Referring to FIG. 7, a method of manufacturing a flexible printed circuit board is new as described above with reference to FIG. 6, but the array manufacturing method is the same as the conventional method. For example, to fabricate an array, devices 700 may be cleaned, laminated 710 devices may be diced 720, filled 730 with a kerf, , And lensing 740 the acoustic lens.

Hereinafter, the performance difference between the ultrasonic transducer and the general ultrasonic transducer according to one embodiment of the present invention will be described with reference to FIGS. 8 to 15. FIG.

FIG. 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. 8 is a result of analysis using a simulation tool such as PZflex.

The upper graph is a graph showing a voltage change with time of a general ultrasonic transducer having a single active layer as a single layer. In the middle graph, the active element is composed of a plurality of layers, FIG. 2 is a graph showing voltage change with time of an ultrasonic transducer including a general flexible printed circuit board on which a conductive layer is formed, and the graph on the lower side shows a flexible printed circuit board, which is a single metal layer, And shows the voltage change with time of the ultrasonic transducer according to the present embodiment. Through the graph comparison shown in FIG. 8, it is confirmed that the ultrasonic transducer of this embodiment has a larger voltage change at the same time.

9 is a graph comparing changes in the normal size according to the frequencies of the ultrasonic transducer and the general ultrasonic transducer according to the embodiment of the present invention. 9 is a result of analysis using a simulation tool such as PZflex.

Referring to FIG. 9, there is shown a variation of a normalized magnitude according to a frequency of a general ultrasonic transducer having a single layer of an active element, a variation of a normalized magnitude of an active element formed of a plurality of layers, And a flexible printed circuit board in which the active element is composed of a plurality of layers and which is a single metal layer. The ultrasonic transducer according to the present embodiment includes a flexible printed circuit board To compare the change of the normal size according to the frequency.

It can be seen from the graph comparison shown in FIG. 9 that the normal size of the ultrasonic transducer of the present embodiment 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. Specifically, FIG. 10 shows the magnitude change at the array transducer level.

As shown in FIG. 10, the impedance of the ultrasonic transducer of this embodiment is smaller than that of general ultrasonic transducers in the small frequency region, and it is confirmed that the impedance mismatch between the transducer and the cable is improved.

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

Specifically, Figure 11 compares the vlotage size versus times of an ultrasonic transducer of the present invention comprising a general ultrasonic transducer with a single layer of active elements and an active element with multiple layers loaded Graph. As shown in Fig. 11, it can be seen that the ultrasonic transducer of the present embodiment has a larger voltage change at the same time.

12 is a graph comparing normalized magnitudes with respect to a frequency of an ultrasonic transducer of the present invention including a general ultrasonic transducer having a single layer of active elements and an active element having a plurality of layers . As shown in FIG. 12, the ultrasonic transducer of the present embodiment shows a larger normal size 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.

The embodiments of the present invention have been described above. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

1, 1a and 1b: ultrasonic transducer 110, 210: backing material
120, 220: flexible printed circuit board 130, 230: active element
140, 240: ground layer 150, 250: matching layer
160, 260: Acoustic lens

Claims (20)

An active element composed of a plurality of layers; And
A flexible printed circuit board which is a single metal layer that directly couples with one surface of at least one layer constituting the active element to supply an electric signal;
And an ultrasonic transducer for transmitting ultrasonic waves to the ultrasonic transducer. The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board
Wherein the conductive metal foil is a single conductive metal foil having a circuit pattern formed thereon. The method according to claim 1,
Wherein the flexible printed circuit board is bonded to one surface of at least one layer of the active element and the active area of the flexible printed circuit board bonded to one surface of the active element is formed of a conductive material corresponding to the formation of the one surface An ultrasonic transducer. The ultrasonic transducer according to claim 1, wherein the ultrasonic transducer
A ground layer which is a single metal layer electrically connected to the active element;
Further comprising an ultrasonic transducer. An active element in which even layers including a first layer and a second layer are stacked;
A backing material positioned on a rear surface of the first layer of the active element and blocking or attenuating ultrasonic waves generated in the active element and propagating to the rear surface;
A matching layer positioned on a front surface of the second layer and matching the acoustic impedance of ultrasonic waves generated in the active element and propagating to the front surface; And
A flexible printed circuit board positioned between the first layer and the second layer of the active element and being a single metal layer electrically connected to the active element;
And an ultrasonic transducer for transmitting ultrasonic waves to the ultrasonic transducer. The flexible printed circuit board according to claim 5, wherein the flexible printed circuit board
Wherein the conductive metal foil is a single conductive metal foil having a circuit pattern formed thereon. 6. The method of claim 5,
Wherein the flexible printed circuit board adheres to one surface of the first layer and the second layer of the active element and the active area of the flexible printed circuit board that adheres to one surface of the first layer and the second layer of the active element, And a conductive material corresponding to the formation of the conductive layer. The ultrasonic transducer according to claim 5, wherein the ultrasonic transducer
A first ground layer positioned between the first layer of the active device and the backing material and being a single metal layer electrically connected to the active device; And
A second ground layer disposed between the second layer of the active device and the matching layer and being a single metal layer electrically connected to the active device;
Further comprising an ultrasonic transducer. 6. The device according to claim 5, wherein the active element
Wherein the plurality of piezoelectric elements are a plurality of piezoelectric elements. 6. The method of claim 5,
Wherein the ultrasonic transducer comprises a plurality of layers. An active element in which odd-numbered layers including a first layer, a second layer and a third layer are stacked;
A backing material positioned on a rear surface of the first layer of the active element and blocking or attenuating ultrasonic waves generated in the active element and propagating to the rear surface;
A matching layer positioned on the front surface of the third layer and matching the acoustic impedance of ultrasonic waves generated in the active element and propagating to the front surface;
A first electrode part positioned 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 positioned between the third layer of the active element and the matching layer and being a single metal layer electrically connected to the active element;
And an ultrasonic transducer for generating ultrasonic waves. 12. The method of claim 11,
Wherein the first electrode portion is a flexible printed circuit board and the second electrode portion is a ground layer. 12. The method of claim 11,
Wherein the first electrode portion is a ground layer and the second electrode portion is a flexible printed circuit board. 12. The plasma display panel of claim 11, wherein the first electrode portion and the second electrode portion
Wherein the conductive metal foil is a single conductive metal foil having a circuit pattern formed thereon. 12. The method of claim 11,
Wherein the first electrode portion is bonded to one surface of at least one layer of the active element and the active 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 is bonded to one surface of at least one layer of the active element and the active region of the second electrode portion bonded to one surface of the active element is formed of a conductive material corresponding to the formation of the one surface. Ultrasonic transducer. 12. The device of claim 11, wherein the active element
Wherein the plurality of piezoelectric elements are a plurality of piezoelectric elements. 12. The method of claim 11, wherein the matching layer
Wherein the ultrasonic transducer comprises a plurality of layers. Forming a flexible printed circuit board; And
Coupling the formed flexible printed circuit board to an active device comprising a plurality of layers; / RTI >
The step of forming the flexible printed circuit board
Cutting a single layer of raw material into a substrate form;
Adhering or thermocompressing the carrier to the cut substrate;
Forming a circuit pattern on a front surface of the substrate which is hot pressed or thermocompressed; And
Attaching a protective layer on an upper surface of the substrate except a pattern in which the active elements are stacked;
Wherein the ultrasonic transducer comprises a plurality of ultrasonic transducers. 19. The method of claim 18, wherein the flexible printed circuit board
Wherein the conductive metal foil is a single conductive metal foil having a circuit pattern formed thereon. The method of manufacturing an ultrasonic transducer according to claim 18,
Forming a ground layer that is a single metal layer; And
Coupling the formed ground layer to the active device;
Wherein the ultrasonic transducer further comprises an ultrasonic transducer.
KR1020140168200A 2014-11-28 2014-11-28 Multi-layered ultrasonic transducer and method for manufacture thereof KR20160064514A (en)

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