Method for manufacturing an ultrasonic transducer

Abstract

The present application discloses a method for manufacturing an ultrasonic transducer, comprising: providing a first element with a through hole and a wax ball that completely closes the through hole, a metal shell, and an interface; filling epoxy conductive glue above the wax ball and inside the first element, and forming a curved surface below the epoxy conductive glue after removing the wax ball; conformally forming a first electrode layer and a piezoelectric layer on the surface of the curved surface and the first element; fixing the first element with the first electrode layer and the piezoelectric layer to one end of the metal shell via an insulating glue; using a first wire to connect the epoxy conductive glue to the center end of the interface, thereby electrically connecting the first electrode layer to the center end of the interface, and the interface is fixedly connected to the other end of the metal shell; conformally forming a second electrode layer on the surface composed of the metal shell, the insulating glue, and the piezoelectric layer, thereby electrically connecting the second electrode layer to the side wall of the interface via the metal shell. The method is conducive to realizing mass production and improving array consistency.

Description

Technical Field

[0001] The present application relates to the technical field of ultrasonic transducers, and in particular to a method for manufacturing an ultrasonic transducer. Background Art

[0002] An ultrasonic transducer is an energy conversion device that converts alternating electrical signals into acoustic signals within the ultrasonic frequency range or converts external acoustic signals into electrical signals.

[0003] The focusing function of an ultrasonic transducer is often achieved through an acoustic lens. Traditional acoustic lenses are often prepared by mechanical grinding or mechanical extrusion to produce the focusing surface of the acoustic lens, and this preparation process is also quite complicated. Summary of the invention

[0004] In response to the problems in the related art, the present application proposes a method for manufacturing an ultrasonic transducer, which can simplify the process steps and save production costs.

[0005] The technical solution of this application is implemented as follows:

[0006] According to one aspect of the present application, a method for manufacturing an ultrasonic transducer is provided, comprising:

[0007] Providing a first element having a through hole, a paraffin ball completely closing the through hole, a metal shell, and an interface;

[0008] Filling epoxy conductive adhesive above the wax ball and inside the first element, and removing the wax ball to form a curved surface below the epoxy conductive adhesive;

[0009] conformally forming a first electrode layer and a piezoelectric layer on the curved surface and the surface of the first element;

[0010] Fixing the first element having the first electrode layer and the piezoelectric layer to one end of the metal housing via insulating glue;

[0011] Using a first wire to connect the epoxy conductive adhesive to the central end of the interface, thereby electrically connecting the first electrode layer to the central end of the interface, and the interface is fixedly connected to the other end of the metal housing;

[0012] A second electrode layer is conformally formed on a surface formed by the metal shell, the insulating glue and the piezoelectric layer, so that the second electrode layer is electrically connected to the side wall of the interface through the metal shell.

[0013] Wherein, a matching layer is formed on the exposed surface of the second electrode layer and the surface of the metal shell.

[0014] Wherein, the first element having the through hole comprises a double-sided polished silicon substrate or a metal column.

[0015] The method for forming the silicon substrate with the through hole comprises: forming a photoresist on the clean surface of the silicon substrate, forming the through hole on the silicon substrate by deep reactive ion etching, and then removing the photoresist.

[0016] Wherein, a plurality of through holes are formed on the silicon substrate, and then the silicon substrate is cut to form the first element having a single through hole.

[0017] Wherein, toluene is used to remove the paraffin balls; after the curved surface is formed, the curved surface is polished and ground to be smooth; the first electrode layer and the piezoelectric layer are formed on the curved surface by sputtering, and the thickness of the piezoelectric layer depends on the target frequency of the ultrasonic transducer.

[0018] The second electrode layer includes a chromium layer formed under the piezoelectric layer and a gold layer formed under the chromium layer.

[0019] Wherein, the interface includes an SMA interface.

[0020] Wherein, the external thread of the interface is fixedly connected to the internal thread of the metal shell.

[0021] The present application forms a curved surface under the epoxy conductive adhesive by using wax balls, and forms an array of through holes using a silicon substrate, thereby facilitating mass production and improving array consistency. Moreover, the curved surface forming process is simple and convenient, saving production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The process steps of a method for manufacturing an ultrasonic transducer according to some embodiments are shown;

[0024] Figure 2 yes Figure 1 The subsequent packaging process steps of the ultrasonic transducer shown;

[0025] Figure 3 The process steps of the method for manufacturing an ultrasonic transducer according to other embodiments are shown;

[0026] Figure 4 yes Figure 3 The subsequent packaging process steps of the ultrasonic transducer are shown. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0028] According to an embodiment of the present application, a method for manufacturing an ultrasonic transducer is provided, which is relatively simple and easy to produce in batches. The steps for forming the ultrasonic transducer will be described in detail below.

[0029] Step S1, see Figure 1 , providing a first component having a through hole 12 and a paraffin ball 13 that completely closes the through hole 12, a metal shell 40, and an interface 50.

[0030] In some embodiments, the first element having the through hole 12 includes Figure 1 The double-sided polished silicon substrate 10 shown in FIG. Figure 3 The metal pillar 80 shown. The metal pillar comprises an aluminum pillar. Figure 1 The method for forming the silicon substrate 10 having the through hole 12 in the first, second, third and fourth steps includes: forming a photoresist 11 on the surface of the clean silicon substrate 10, forming the through hole 12 on the silicon substrate 10 by deep reactive ion etching, and then removing the photoresist 11.

[0031] The detailed method is as follows: 1. Take a double-sided polished 400um thick silicon substrate 10 and clean it to remove the impurity ions on the surface of the silicon substrate 10; 2. In ICP (Inductive Coupled Plasma, i.e. inductively coupled plasma etching) and DRIE (Deep Reactive Ion Etching, i.e. deep reactive ion etching technology), 12um-15um photoresist 11AZ6130, SF 6 As etching gas, C 4 F 8 As a passivation gas, an appropriate electric field is generated in the plasma chamber with an appropriate bias voltage to vertically impact the photoresist 11 at the bottom of the etched groove. 6 , C 4 F 8 By adjusting other process parameters such as flow rate, etching, passivation cycle, etc., a through hole 12 with vertical side walls can be finally obtained; 3. The silicon wafer is cleaned successively with acetone, ethanol and deionized water to remove the photoresist 11 on the surface of the silicon substrate 10, thereby obtaining a through hole 12 with a diameter of 3 mm.

[0032] Step S2, see Figure 1In the fifth and sixth steps, epoxy conductive adhesive 14 is filled above the wax ball 13 and inside the first element, and then left to solidify at room temperature for 24 hours, and then toluene is used to remove the wax ball 13 to form a curved surface below the epoxy conductive adhesive 14. After the curved surface is formed, the curved surface can be polished and smoothed. The epoxy conductive adhesive 14 is silver glue, which is used to form a focusing curved surface and is used as a backing.

[0033] Step S3, see Figure 2 In steps a and b, the first electrode layer 20 and the piezoelectric layer 21 are conformally formed on the curved surface and the surface of the first element. The first electrode layer 20 and the piezoelectric layer 21 can be formed on the curved surface by sputtering, and the thickness of the piezoelectric layer 21 depends on the target frequency of the ultrasonic transducer.

[0034] Step S4, after forming a plurality of through holes 12 on the silicon substrate 10, cutting the silicon substrate 10 to form a first element having a single through hole 12. In some embodiments, the silicon substrate 10 is cut into 4×4 mm 2 The size blocks are divided, wherein a through hole 12 with a diameter of 3 mm is located at the center of each divided block.

[0035] Step S5, see Figure 2 In step c, the first element having the first electrode layer 20 and the piezoelectric layer 21 is fixed to one end of the metal shell 40 via the insulating glue 30. The first element is located in the metal shell 40. In addition to fixing the first element and the metal shell 40, the insulating glue 30 also serves to isolate the first electrode layer 20 and the second electrode layer 60. The metal shell 40 serves as an electromagnetic shield.

[0036] Step S6, see Figure 2 In step d, the epoxy conductive adhesive 14 is connected to the central end of the interface 50 using the first wire 51, thereby electrically connecting the first electrode layer 20 to the central end of the interface 50, and the interface 50 is fixedly connected to the other end of the metal shell 40. In some embodiments, the external thread of the interface 50 is fixedly connected to the internal thread of the metal shell 40. The interface 50 includes an SMA (i.e., Sub-Miniature A Connector, i.e., the abbreviation of a subminiature connector) interface 50.

[0037] Step S7, see Figure 2In step e, a second electrode layer 60 is conformally formed on the surface composed of the metal housing 40, the insulating adhesive 30, and the piezoelectric layer 21, thereby electrically connecting the second electrode layer 60 to the sidewall of the interface 50 via the metal housing 40. In some embodiments, the second electrode layer 60 includes a 50-nm chromium layer formed under the piezoelectric layer 21 and a 100-nm gold layer formed under the chromium layer. The chromium layer serves as an adhesion layer. The material of the first electrode layer 20 and the material of the second electrode layer 60 may be the same or different. The piezoelectric layer 21 includes zinc oxide, aluminum nitride, lead zirconate titanate (PZT), or scandium-doped aluminum nitride, polyvinylidene fluoride polymer (PVDF), or other suitable materials. The sidewall and the central end of the interface 50 are used to input electrical signals.

[0038] Step S8, refer to Figure 2 In step f, a matching layer 70 is formed on the exposed surface of the second electrode layer 60 and the surface of the metal housing 40. The matching layer 70 is also formed on the sidewall of the metal housing 40 and can prevent the conduction of the circuit if tested in water later. The material of the matching layer 70 includes parylene-C (i.e., Parylene-C), which is used to reduce the acoustic impedance difference between the piezoelectric layer 21 and the detection object, so that the main part of the ultrasonic wave generated from the piezoelectric layer 21 can be transmitted to the detection object.

[0039] Thus far, an ultrasonic transducer has been manufactured through the above process.

[0040] Refer to Figure 3 and Figure 4 shown in the embodiments of the manufacturing method of the ultrasonic transducer, which is different from the embodiments shown in Figure 1 and Figure 2 in that Figure 1 and Figure 2 in the embodiments, the through hole 12 is formed by etching the silicon substrate 10, while Figure 3 and Figure 4 the through hole 12 in

[0041] In summary, the piezoelectric layer 21 of the ultrasonic transducer provided in the present application generates ultrasonic waves under the excitation of electrical signals and focuses them onto a specific area through a curved surface, thereby detecting the surface of the specific area. The epoxy conductive adhesive 14 absorbs the ultrasonic signals propagated from the piezoelectric layer 21 to the epoxy conductive adhesive 14, effectively reducing the reflection of the ultrasonic signals, thereby improving the detection resolution. The present application forms a curved surface under the epoxy conductive adhesive 14 through the paraffin balls 13 and uses the silicon substrate 10 to form an array of through holes 12, which is conducive to realizing mass production and improving the array consistency. Moreover, the process of forming the curved surface is simple, saving the production cost.

[0042] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for manufacturing an ultrasonic transducer, It is characterized in that include: Providing a first element having a through hole and a paraffin ball completely closing the through hole; Provide metal housing and interfaces; Filling epoxy conductive adhesive above the wax ball and inside the first element, removing the wax ball to form a curved surface below the epoxy conductive adhesive; conformally forming a first electrode layer and a piezoelectric layer on the curved surface and the surface of the first element; Fixing the first element having the first electrode layer and the piezoelectric layer to one end of the metal housing via insulating glue; Using a first wire to connect the epoxy conductive adhesive to the central end of the interface, thereby electrically connecting the first electrode layer to the central end of the interface, and the interface is fixedly connected to the other end of the metal housing; A second electrode layer is conformally formed on a surface formed by the metal shell, the insulating glue and the piezoelectric layer, so that the second electrode layer is electrically connected to the side wall of the interface through the metal shell.

2. The method for manufacturing an ultrasonic transducer according to claim 1, It is characterized in that A matching layer is formed on the exposed surface of the second electrode layer and the surface of the metal shell.

3. The method for manufacturing an ultrasonic transducer according to claim 1, It is characterized in that The first element having the through hole includes a double-sided polished silicon substrate or a metal column.

4. The method for manufacturing an ultrasonic transducer according to claim 3, It is characterized in that The method for forming the silicon substrate with the through hole comprises: forming a photoresist on the clean surface of the silicon substrate, forming the through hole on the silicon substrate by deep reactive ion etching, and then removing the photoresist.

5. The method for manufacturing an ultrasonic transducer according to claim 4, It is characterized in that A plurality of through holes are formed on the silicon substrate, and then the silicon substrate is cut to form the first element of a single through hole.

6. The method for manufacturing an ultrasonic transducer according to claim 1, It is characterized in that The paraffin balls are removed by toluene; after the curved surface is formed, the curved surface is polished and ground to be smooth; the first electrode layer and the piezoelectric layer are formed on the curved surface by sputtering, and the thickness of the piezoelectric layer depends on the target frequency of the ultrasonic transducer.

7. The method for manufacturing an ultrasonic transducer according to claim 1, It is characterized in that The second electrode layer includes a chromium layer formed under the piezoelectric layer and a gold layer formed under the chromium layer.

8. The method for manufacturing an ultrasonic transducer according to claim 1, It is characterized in that The interface includes an SMA interface.

9. The method for manufacturing an ultrasonic transducer according to claim 1, It is characterized in that The external thread of the interface is fixedly connected to the internal thread of the metal shell.

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