Preparation method and application of adhesive-free multi-impedance matching layer

Abstract

The invention relates to the technical field of ultrasonic detection and medical instruments, in particular to a preparation method and application of an adhesive-free multi-impedance matching layer, and the preparation method comprises the following steps: S1, preparing a glue solution P1 from the adhesive-free multi-impedance matching layer; s2, pouring the prepared glue solution P1 on the surface of a tool, and carrying out vacuum defoaming and curing molding; s3, the tool is placed on a high-precision grinding machine to be ground, and a first matching layer is formed; s4, preparing a glue solution P2, pouring the glue solution P2 on the first matching layer, and carrying out vacuum defoaming and curing molding; s5, the tool is placed on a high-precision grinding machine to be ground, and a second matching layer is formed on the first matching layer; s6, repeating the steps S4 and S5, and preparing a third matching layer on the second matching layer; and S7, cutting according to a preset size by using a cutting machine to obtain the adhesive-free multi-impedance matching layer. The method is easy to operate and low in grinding machining difficulty, the preparation efficiency can be effectively improved, and control over the product quality is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic detection and medical equipment, and in particular to a preparation method and application of an adhesive-free multi-impedance matching layer. Background Art

[0002] Ultrasound is a mechanical wave with a very short wavelength, which is generally shorter than 2 cm in the air. Due to the short wavelength of ultrasound, it is easier to obtain anisotropic sound energy, which can be used for cleaning, stone crushing, sterilization and disinfection, and has many applications in medicine and industry.

[0003] Ultrasonic transducer is an energy conversion device that can convert electrical signals into ultrasonic signals and send them out or receive echoes and convert them into electrical signals for further processing; it is usually widely used in ultrasonic processing, ultrasonic detection, testing, monitoring, telemetry, remote control and other fields; in addition, due to its characteristics of large effective distance and wide bandwidth, as well as obvious advantages such as no radiation, real-time dynamic imaging, and observable blood flow, it has been widely used in medical diagnosis, treatment, ultrasonic flaw detection and many other occasions.

[0004] The replacement of ultrasonic transducers is an important part of the development of medical ultrasonic diagnostic systems, especially medical ultrasonic transducers. With the development of medical technology, interventional surgery is becoming more and more widely used, and interventional ultrasonic medical devices have also achieved unprecedented development. Correspondingly, the application of ultrasonic transducers in medical procedures is also becoming more and more extensive. However, due to the limitations of interventional ultrasound application scenarios, the requirements for the size and image quality of ultrasonic transducers are getting higher and higher. Multi-matching layers are one of the commonly used and effective methods to improve image quality.

[0005] The traditional method of preparing multi-layer matching layers is to mix the prefabricated materials in the corresponding proportions to form a single matching layer, and then use a vacuum suction cup to adsorb the prepared single matching layer on a grinder to process it into the required size, and finally use an adhesive to bond them together in a stacking fixture to form a multi-layer matching layer. At present, the number of matching layers in commonly used ultrasonic transducers is generally 1-3 layers. In order to further broaden the bandwidth and obtain better impedance matching, the number of matching layers can only be increased on this basis; however, as the number of matching layers increases, the thickness of each matching layer needs to be thinner. The traditional vacuum adsorption post-grinding method and matching layer grinding processing method are difficult to meet the thickness and flatness requirements of more layers of matching layers, and the matching layers are easily broken and damaged during the adsorption, grinding, and stacking processes, resulting in low preparation efficiency and high defective rate. It can be seen from this that although increasing the number of matching layers can better optimize impedance matching to obtain the best image quality; however, as the number of matching layers increases, the difficulty of the preparation process also increases; and more layers of adhesive will also lead to more energy loss, thereby reducing image resolution and affecting image quality. Therefore, optimizing impedance matching by increasing the number of matching layers is limited by the preparation process and cannot be easily achieved. Therefore, it is urgent to develop a method for preparing adhesive-free multi-impedance matching layers.

[0006] The present invention provides a method for preparing an adhesive-free multi-impedance matching layer and its application, so as to solve the problems in the prior art that the existing preparation process cannot meet the thickness and flatness requirements of more matching layers and the preparation cost is high. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing an adhesive-free multi-impedance matching layer and its application, so as to solve the problems in the prior art that the existing preparation process cannot meet the thickness and flatness requirements of more matching layers and the preparation cost is high.

[0008] The technical solution of the present invention is: a method for preparing an adhesive-free multi-impedance matching layer, comprising the following steps:

[0009] S1, weighing raw materials and additives in proportion, and preparing them to form glue P1; the raw materials include epoxy resin; the additives include curing agent;

[0010] S2, select a piece of tooling, and attach a barrier layer around the tooling, pour the prepared glue P1 on the surface of the tooling, perform vacuum degassing, and then put it into an oven for curing and forming, so as to form a first matching layer blank on the surface of the tooling; the barrier layer is made of high temperature resistant material;

[0011] S3, placing the tooling with the first matching layer blank on the surface on a high-precision grinder for grinding, the preset thickness of the first matching layer is X1, the thickness of the tooling is A, the total thickness after grinding is A+X1, and the first matching layer is formed on the surface of the tooling after grinding;

[0012] S4, preparing glue liquid P2, wiping, cleaning and drying the first matching layer on the surface of the tooling, and pasting a barrier layer on the side of the first matching layer, then pouring the glue liquid P2 on the first matching layer, performing vacuum degassing and curing to form a second matching layer blank;

[0013] S5, placing the tooling with the second matching layer blank on the surface on a high-precision grinder for grinding, the thickness of the second matching layer is preset to be X2, and the total thickness after grinding is A+X1+X2, and after the grinding is completed, the second matching layer is formed on the first matching layer;

[0014] S6, repeating steps S4 and S5, preparing the third matching layer, ..., and the nth matching layer on the second matching layer in sequence, and presetting the thicknesses of the third matching layer 3, ..., and the nth matching layer to be X3, ..., ... n , the total thickness after grinding is A+X1+X2+X3+…+X n ,After grinding is completed, an adhesive-free multi-impedance matching layer is formed on the tooling;

[0015] S7. Remove the prepared adhesive-free multi-impedance matching layer from the tooling, cut it into a preset size using a precision cutting machine, remove excess parts, and obtain an adhesive-free multi-impedance matching layer with a preset size.

[0016] Preferably, the epoxy resin is any one or more combinations of epoxy 615 resin, epoxy 616 resin, epoxy 301 resin, epoxy E51 resin, and epoxy E41 resin.

[0017] Preferably, in S4, the raw materials used to prepare the glue solution P2 include a resin of the same type as the epoxy resin used to prepare the glue solution P1.

[0018] Preferably, the curing agent is any one of curing agent 230 , curing agent 651 , curing agent 593 , and curing agent 596 .

[0019] Preferably, the tooling is made of pure metal material or alloy material; the flatness of the tooling is checked before use.

[0020] Preferably, the tooling is made of stainless steel.

[0021] Preferably, the solution used to wipe the first matching layer in S4 is any one of isopropyl alcohol, anhydrous ethanol and anhydrous methanol.

[0022] The present invention also provides the use of the adhesive-free multi-impedance matching layer prepared by the preparation method in a transducer.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The present invention provides a preparation method and application of an adhesive-free multi-impedance matching layer. The preparation method is simpler to operate and has low difficulty in grinding during the preparation process. It can not only meet the thickness and flatness requirements of preparing more layers of matching layers, but also effectively improve the preparation efficiency and help control product quality. At the same time, the adhesive-free multi-impedance matching layer prepared by the preparation method has multiple matching layers, and no adhesive is required to bond the matching layers. When the prepared adhesive-free multi-impedance matching layer is applied to a transducer, it can not only improve the bandwidth of the transducer, but also effectively reduce energy loss and improve image resolution and performance. It can also avoid the adverse effects of chemical substances released by the adhesive on the human body, thereby improving the safety of transducer use. It solves the problems existing in the prior art that the preparation process cannot meet the thickness and flatness requirements of more layers of matching layers and the preparation cost is high.

[0025] (2) The present invention provides a preparation method and application of an adhesive-free multi-impedance matching layer. When the preparation method is used to prepare the adhesive-free multi-impedance matching layer, the thickness after each grinding is the sum of the tooling thickness and the matching layer thickness, and the thickness value is relatively large; it can effectively reduce the difficulty of grinding processing in the preparation process and improve the efficiency of grinding processing; the preparation method can also save the process steps of bonding each matching layer to each other, and at the same time, it does not require the use of complex and precise tooling, which can greatly improve the efficiency and yield of preparing the adhesive-free multi-impedance matching layer, saving material costs and equipment use and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0027] Figure 1 The adhesive-free multi-impedance matching layer prepared in the first embodiment of the present invention;

[0028] Figure 2 The four matching layers prepared in Comparative Example 1 of the present invention;

[0029] Wherein: 1. first matching layer; 2. second matching layer; 3. third matching layer; 4. fourth matching layer; 5. single matching layer; 6. adhesive. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific embodiments:

[0031] A method for preparing an adhesive-free multi-impedance matching layer specifically comprises the following steps:

[0032] S1. Weigh the raw materials and additives according to a certain ratio, put the weighed raw materials and additives into a reaction container and mix them evenly to prepare glue P1. The raw materials used to prepare glue P1 include at least epoxy resin; the additives used include at least curing agent. Among them, the epoxy resins that can be used to prepare glue P1 mainly include epoxy 615 resin, epoxy 616 resin, epoxy 301 resin, epoxy E51 resin, epoxy E41 resin, etc.; in the present invention, epoxy 615 resin or epoxy 616 resin is preferably used as a raw material to prepare glue P1. The prepared glue P1 can be a single epoxy resin glue or an epoxy resin composite glue; that is, the raw material for preparing glue P1 is a combination of one or more epoxy resins; or, the raw materials for preparing glue P1 include one or more epoxy resins, and also include other raw materials except epoxy resin. The curing agents used to prepare the glue P1 mainly include epoxy resin curing agents and silicone curing agents; among them, epoxy resin curing agents are the most commonly used curing agents; there are many types of epoxy resin curing agents, including amine curing agents, polyamide curing agents, etc.; amine curing agents can form cross-linked structures when reacting with epoxy resins, which can significantly improve the performance of materials, such as polyamines and polyamide resins; and polyamide curing agents, because they contain active amino groups in their molecules, can not only be used as curing agents, but also as toughening agents to improve the weather resistance and construction performance of materials; therefore, a suitable curing agent can be selected according to the performance requirements of the matching layer. In the present invention, curing agents such as curing agent 230, curing agent 651, curing agent 596, curing agent 593, and curing agent 594 are preferably used. Additives may also include other additives for enhancing the physical strength performance of the matching layer, or metal powders.

[0033] S2, select a piece of tooling, and stick a barrier layer on the side of the tooling, then pour the glue P1 prepared in step S1 on the surface of the tooling, and then vacuum degas the glue P1 on the surface of the tooling. After the degassing is completed, put the tooling into an oven, and solidify the glue P1 on the surface of the tooling to form the first matching layer blank on the surface of the tooling. Sticking a barrier layer on the side of the tooling is mainly used to prevent the glue from overflowing outside the tooling and causing waste of glue during the process of pouring the glue on the surface of the tooling. It can also effectively prevent the glue overflowing outside the tooling from adhering the tooling or other objects to the operating table. Since the tooling needs to be placed in an oven for heating during the preparation of the matching layer blank, the barrier layer attached to the side of the tooling needs to have high temperature resistance; therefore, the barrier layer needs to be made of high temperature resistant material; in the present invention, high temperature resistant kraft paper is often used as the barrier layer. In addition, in order to ensure that the tooling can be stably adsorbed on the grinding disc, the tooling used in the present invention needs to have a certain degree of magnetism; that is, the tooling is usually made of pure metal materials or alloy materials with a certain degree of magnetism.

[0034] S3, placing the tooling with the first matching layer blank on the surface on a high-precision grinder for grinding, the preset thickness of the first matching layer is X1, the thickness of the tooling is A, the total thickness after grinding is A+X1, and the first matching layer is formed on the surface of the tooling after grinding. Since the tooling is made of metal material or metal alloy material, the surface of the tooling may rust. In order to avoid the occurrence of problems such as the performance reduction of the prepared matching layer caused by the contamination of the glue poured on the surface of the tooling by rust stains, the tooling used in the present invention is preferably made of stainless steel.

[0035] S4, prepare glue P2, wipe, clean and dry the first matching layer on the surface of the tooling at the same time, and stick a barrier layer on the side of the first matching layer, then pour the glue P2 on the first matching layer, perform vacuum degassing, and solidify to form a second matching layer blank. The raw material used to prepare the glue P2 can be one or a combination of various resins used to prepare matching layers, but must include a resin of the same type as the epoxy resin used to prepare the glue P1. When wiping and cleaning the first matching layer on the surface of the tooling, isopropyl alcohol, anhydrous ethanol, anhydrous methanol and other solutions can be used to wipe and clean the first matching layer; after wiping and cleaning the first matching layer, the first matching layer must be dried before the next step to ensure that no isopropyl alcohol, anhydrous ethanol, anhydrous methanol and other solutions remain on the first matching layer, thereby effectively avoiding the residual wiping solution from affecting the adhesiveness of the glue P2 and causing the first matching layer to be unable to fit tightly with the second matching layer.

[0036] S5, placing the tooling with the second matching layer blank on the surface on a high-precision grinder for grinding, the thickness of the second matching layer is preset to be X2, and the total thickness after grinding is A+X1+X2, and after the grinding is completed, the second matching layer is formed on the first matching layer;

[0037] S6, repeating steps S4 and S5, preparing the third matching layer, ..., and the nth matching layer on the second matching layer in sequence, and presetting the thicknesses of the third matching layer 3, ..., and the nth matching layer to be X3, ..., ... n , the total thickness after grinding is A+X1+X2+X3+…+X n ,After grinding is completed, an adhesive-free multi-impedance matching layer is formed on the tooling;

[0038] S7. Remove the prepared adhesive-free multi-impedance matching layer from the tooling, cut it according to a preset size using a precision cutting machine, remove excess parts, and obtain an adhesive-free multi-impedance matching layer with a preset size.

[0039] Implementation Method 1

[0040] S1, weighing epoxy 615 resin and 596 curing agent in a ratio of 10:1, and fully mixing the weighed epoxy 615 resin and 596 curing agent to form glue solution P1;

[0041] S2. Select a piece of tooling made of stainless steel and with qualified flatness inspection, and stick a layer of kraft paper around the side of the tooling; then pour the glue liquid P1 prepared in S1 onto the surface of the tooling, and vacuum degas the glue liquid P1 on the surface of the tooling, and then put the tooling into an oven to solidify the glue liquid P1 on the surface of the tooling, so that the glue liquid P1 forms a first matching layer blank on the surface of the tooling.

[0042] S3, placing the tooling with the first matching layer blank on the surface on a high-precision grinder for grinding, the preset thickness of the first matching layer 1 is 0.2 mm, the thickness of the tooling is 20 mm, the total thickness after grinding is 20.2 mm, and the first matching layer 1 is formed on the surface of the tooling after grinding;

[0043] S4, weighing epoxy 615 resin, epoxy 616 resin and 596 curing agent respectively in a ratio of 5:5:1, and mixing the weighed epoxy 615 resin, epoxy 616 resin and 596 curing agent evenly to prepare glue solution P2; at the same time, using isopropyl alcohol to wipe and clean the first matching layer 1 on the surface of the tooling, and then drying it; then sticking a layer of kraft paper around the side of the first matching layer 1, and pouring the glue solution P2 on the first matching layer 1; then vacuum degassing and curing it to form a second matching layer blank;

[0044] S5, placing the tooling with the second matching layer blank on the surface on a high-precision grinder for grinding, the preset thickness of the second matching layer 2 is 0.1 mm, and the total thickness after grinding is 20.3 mm. After grinding, the second matching layer 2 is formed on the first matching layer 1;

[0045] S6, repeating steps S4 and S5, preparing glue P3, and making the third matching layer 3 on the second matching layer 2, the preset thickness of the third matching layer 3 is 0.05mm, and the total thickness after grinding is 20.35mm; after grinding, the third matching layer 3 is obtained; repeating steps S4 and S5 again, preparing glue P4, and making the fourth matching layer 4 on the third matching layer 3, the preset thickness of the fourth matching layer 4 is 0.008mm, and the total thickness after grinding is 20.358mm; after grinding, an adhesive-free multi-impedance matching layer with four matching layers is formed on the tooling. The matching layers of the adhesive-free multi-impedance matching layer are closely attached to each other, that is, the first matching layer 1 and the second matching layer 2, the second matching layer 2 and the third matching layer 3, and the third matching layer 3 and the fourth matching layer 4 are closely attached in sequence through the glue used in the preparation process, and their own adhesive properties.

[0046] S7, removing the prepared adhesive-free multi-impedance matching layer from the tooling, cutting it according to a preset size with a precision cutting machine, removing the excess part, and preparing an adhesive-free multi-impedance matching layer with a preset size; Figure 1 As shown, the thickness of the adhesive-free multi-impedance matching layer is 0.358 mm.

[0047] In other embodiments, the above method can be used to prepare an adhesive-free multi-impedance matching layer with two matching layers or an adhesive-free multi-impedance matching layer with three matching layers; steps S4 and S5 can also be repeated multiple times to prepare an adhesive-free multi-impedance matching layer with more than three matching layers. In other embodiments, glue P1 and glue P2, glue P1 and glue P3, glue P3 and glue P2, etc. can be glues prepared with the same formula or with different formulas, but when glues prepared with different formulas are used, the raw materials used to prepare the glue must contain the same type of epoxy resin; this is because according to the principle of "like dissolves like", the raw materials contain the same epoxy resin, and the adhesive effect between the two glues is better, thereby making the two matching layers prepared in sequence fit more closely.

[0048] Comparative Example 1

[0049] The epoxy 615 resin material and 596 curing agent required for preparing the matching layer are mixed in a ratio of 10:1 to form a glue solution Q1, and then the glue solution Q1 is evenly poured into a container, vacuum degassed, and then placed in an oven for curing to form a single matching layer; the prepared single matching layer is then adsorbed on a grinder using a vacuum suction cup and processed into a required size; the above steps are repeated multiple times to prepare a plurality of single matching layers with the same and / or different thicknesses for standby use; finally, four single matching layers with thicknesses of 0.2 mm, 0.1 mm, 0.05 mm, and 0.008 mm are taken from the single matching layers prepared above, and the four single matching layers are sequentially bonded to each other in a stacking jig using an adhesive to form four matching layers; Figure 2 As shown, there is a layer of adhesive between the four matching layers; wherein the thicknesses of the four single matching layers are 0.2 mm, 0.1 mm, 0.05 mm, and 0.008 mm, respectively, and the average thickness of each layer of adhesive is preset to be 0.003 mm. The total thickness of the four matching layers is 0.358+3×0.003 mm, i.e., 0.367 mm.

[0050] By comparing the first embodiment with the first comparative example, it can be seen that when the thickness of each matching layer is the same, the thickness of the adhesive-free multi-impedance matching layer prepared by the preparation method provided by the present invention is significantly less than the thickness of the multi-matching layer prepared by the traditional adhesive method; accordingly, when preparing multi-matching layers of the same thickness, the thickness requirement of each matching layer is lower when the preparation method provided by the present invention is used compared with the traditional preparation method. At the same time, in the process of preparing the multi-matching layer by the preparation method provided by the present invention, the thickness after each grinding is the thickness of the tooling plus the thickness of the matching layer on the tooling, that is, A+X1+…, the thickness value is large, the grinding difficulty is low, the precision requirement of the grinding equipment is also low, and the requirements of the flatness of each matching layer and the flatness of the multi-matching layer can be met; however, in the process of preparing the multi-matching layer by the traditional adhesive method, the grinding thickness is the thickness of each matching layer, and the thickness value of each single matching layer is very low, the grinding difficulty is very large, not only the precision requirement of the grinding equipment is very high, but also it is more likely to be damaged during the grinding process, resulting in low grinding efficiency and low grinding yield; and it is also unable to meet the requirements of the flatness of the multi-matching layer. Secondly, when the traditional gluing method is used to prepare the multi-matching layer, during the operation, the single matching layer is prone to collision, which will cause the single matching layer to be broken or damaged, thereby increasing the loss of the single matching layer and resulting in a high preparation cost of the multi-matching layer; and when the traditional gluing method is used to prepare the multi-matching layer, more adhesives are needed; and many adhesives contain organic solvents, such as benzene, toluene, xylene, acetone, etc., most of which are volatile and will be released into the air during use; long-term contact or inhalation of high-concentration organic solvent vapors will cause damage to the human nervous system, liver, kidneys, etc.; however, in the process of preparing the multi-matching layer using the preparation method provided by the present invention, no adhesive is needed, and the single matching layer will not be prone to collision, resulting in the phenomenon of single matching layer being broken or damaged. In addition, when using the preparation method provided by the present invention to prepare a multi-matching layer with 4 matching layers, the total working time required is about 4 hours, and the yield rate is about 80%; while when using the traditional gluing method to prepare a multi-matching layer with 4 matching layers, the total working time required is about 8 hours, and the yield rate is about 60%. It can be seen that compared with the traditional gluing method, the preparation method provided by the present invention to prepare the multi-matching layer can not only save the cost of raw materials, equipment use and maintenance costs; it can also reduce the difficulty of the process, meet the thickness and flatness requirements of the multi-matching layer, and improve the production efficiency and yield rate; at the same time, there is no need to use adhesives, avoiding the release of organic solvents causing serious damage to the human body. The adhesive-free multi-impedance matching layer prepared by the above preparation method provided by the present invention can be widely used in various forms of transducers.

[0051] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for preparing an adhesive-free multi-impedance matching layer, characterized in that: The following steps are involved: S1, weighing raw materials and additives in proportion, and preparing them to form glue P1; the raw materials at least include epoxy resin; the additives at least include curing agent; S2, select a piece of tooling, and attach a barrier layer around the tooling, pour the prepared glue P1 on the surface of the tooling, perform vacuum degassing, and then put it into an oven for curing and forming, so as to form a first matching layer blank on the surface of the tooling; The barrier layer is made of high temperature resistant material; S3, placing the tooling with the first matching layer blank on the surface on a high-precision grinder for grinding, the preset thickness of the first matching layer is X1, the thickness of the tooling is A, the total thickness after grinding is A+X1, and the first matching layer is formed on the surface of the tooling after grinding; S4, preparing glue liquid P2, wiping, cleaning and drying the first matching layer on the surface of the tooling, and pasting a barrier layer on the side of the first matching layer, then pouring the glue liquid P2 on the first matching layer, performing vacuum degassing and curing to form a second matching layer blank; S5, placing the tooling with the second matching layer blank on the surface on a high-precision grinder for grinding, the thickness of the second matching layer is preset to be X2, and the total thickness after grinding is A+X1+X2, and after the grinding is completed, the second matching layer is formed on the first matching layer; S6, repeating steps S4 and S5, preparing the third matching layer, ..., and the nth matching layer on the second matching layer in sequence, and presetting the thicknesses of the third matching layer 3, ..., and the nth matching layer to be X3, ..., ... n , the total thickness after grinding is A+X1+X2+X3+…+X n ,After grinding is completed, an adhesive-free multi-impedance matching layer is formed on the tooling; S7. Remove the prepared adhesive-free multi-impedance matching layer from the tooling, cut it into a preset size using a precision cutting machine, remove excess parts, and obtain an adhesive-free multi-impedance matching layer with a preset size.

2. The method for preparing an adhesive-free multi-impedance matching layer according to claim 1, characterized in that: The epoxy resin is any one or more combinations of epoxy 615 resin, epoxy 616 resin, epoxy 301 resin, epoxy E51 resin, and epoxy E41 resin.

3. The method for preparing an adhesive-free multi-impedance matching layer according to claim 2, characterized in that: In S4, the raw materials used to prepare the glue solution P2 include a resin of the same type as the epoxy resin used to prepare the glue solution P1.

4. The method for preparing an adhesive-free multi-impedance matching layer according to claim 2, characterized in that: The curing agent is any one of curing agent 230 , curing agent 651 , curing agent 593 , and curing agent 596 .

5. The method for preparing an adhesive-free multi-impedance matching layer according to claim 1, characterized in that: The tooling is made of pure metal material or alloy material; the flatness of the tooling is checked before use.

6. The method for preparing an adhesive-free multi-impedance matching layer according to claim 5, characterized in that: The tooling is made of stainless steel.

7. The method for preparing an adhesive-free multi-impedance matching layer according to claim 1, characterized in that: The solution used to wipe the first matching layer in S4 is any one of isopropyl alcohol, anhydrous ethanol and anhydrous methanol.

8. Use of the adhesive-free multi-impedance matching layer according to any one of claims 1 to 7 in a transducer.

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