Ultrasonic transducer and method for preparing the same

Abstract

The invention belongs to the field of ultrasonic transducers, and specifically relates to an ultrasonic transducer and a preparation method thereof; the method comprises: a substrate is provided with two connecting posts, the substrate is arranged on the upper part of a metal shell, a negative electrode of a piezoelectric ceramic sheet is bonded to the bottom of the metal shell by conductive glue, a thick wire is connected to the positive electrode of the piezoelectric ceramic sheet and the first connecting post; a sound absorbing structure is filled in the metal shell; one end of a copper electrode is welded to the second connecting post by a welding spot, the other end of the copper electrode is bonded to the metal shell by conductive glue, and a thin wire is respectively connected to the first connecting post and the second connecting post; a sealant is coated on the upper part of the substrate to seal the substrate; in the ultrasonic transducer designed by the invention, the electrical connection is less affected by the environment and has high reliability.

Description

Technical Field

[0001] The present invention belongs to the field of ultrasonic transducers, and particularly relates to an ultrasonic transducer and a preparation method thereof. Background Art

[0002] At present, the performance of commercially available ultrasonic sensors can meet the application requirements of most applications. However, the operating temperature range of commercial devices usually cannot meet some special application environments. When the temperature is higher or lower than the upper and lower limits of its operating temperature, its performance will be affected, and even electrical open circuits may occur. Especially when using conductive adhesives and other methods to achieve electrical connection, the above situation is more likely to occur due to temperature changes.

[0003] The ultrasonic transducers commonly used in reverse radars mostly use aluminum shells. The characteristics of aluminum shells are easy to process and low cost; and at the same size, the resonance frequency is lower; one of the disadvantages of aluminum shells is that it is not easy to weld wires, and the shell is usually directly connected to the negative electrode of the piezoelectric ceramic sheet. Therefore, some transition structures are needed to connect the shell and the pins of the piezoelectric ceramic sheet together, and wires can be welded on the transition structure to avoid welding wires on the aluminum shell. A common method is that the copper electrode on the outer edge of the circuit board is connected to the negative electrode of the pin, and then the circuit board and the shell are glued together with conductive adhesive. At this time, the copper electrode is sandwiched in the middle of the PCB board, and only the circular cross-section is connected to the shell through conductive adhesive. Once passing through high and low temperature environments, thermal expansion and contraction may cause the circuit board to fall off from the aluminum shell, resulting in electrical connection failure. It is necessary to improve the traditional electrical connection method and design a new transition structure to solve the existing problems. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides an ultrasonic transducer and a preparation method thereof. The method includes: a piezoelectric ceramic sheet 1, a metal shell 2, a thin wire 3, a substrate 4, a sealant 5, a thick wire 6, a connecting post 7, a solder joint 8, a conductive adhesive 9, a copper electrode 11, and an acoustic absorption structure 12; the substrate 4 is provided with two connecting posts 7, the substrate 4 is arranged on the upper part of the metal shell 2, the negative electrode of the piezoelectric ceramic sheet 1 is adhered to the bottom of the metal shell 2 through the conductive adhesive 9, the thick wire 6 connects the positive electrode of the piezoelectric ceramic sheet 1 and the first connecting post 7; the metal shell 2 is filled with the acoustic absorption structure 12; one end of the copper electrode 11 is welded to the second connecting post 7 through the solder joint 8, the other end of the copper electrode 11 is adhered to the metal shell 2 through the conductive adhesive 9, and each of the first connecting post 7 and the second connecting post 7 is connected with a thin wire 3; the sealant 5 is coated above the substrate 4 to seal the substrate 4.

[0005] Preferably, a protrusion is provided on the upper part of the inner surface of the metal shell 2, and the substrate 4 is arranged on the protrusion and fixed to the protrusion with an adhesive 10.

[0006] Preferably, the substrate 4 is provided with ventilation holes to ensure the air pressure balance inside and outside the device.

[0007] Preferably, the copper electrode 11 is a soft copper foil or a single-conductor copper strip.

[0008] Preferably, the substrate 4 is a PCB board.

[0009] A method for preparing an ultrasonic transducer, comprising:

[0010] S1: Welding one end of a fine wire to the positive electrode of a piezoelectric ceramic sheet;

[0011] S2: Adhering the negative electrode of the piezoelectric ceramic sheet to the bottom of the metal housing with a conductive adhesive;

[0012] S3: Filling the metal housing with an acoustic absorption structure;

[0013] S4: Designing and processing a substrate with two connecting posts, wrapping one end of the copper electrode around the substrate, and welding the other end of the copper electrode to the second connecting post by soldering;

[0014] S5: Welding the other end of the fine wire to the first connecting post;

[0015] S6: Installing the substrate into the housing and supporting it by the protrusions inside the housing to form a stable supporting state;

[0016] S7: Realizing electrical connection between the copper electrode and the housing with a conductive adhesive;

[0017] S8: Selecting a plurality of uniformly distributed points at positions other than the copper electrode between the substrate and the housing and fixing them with an adhesive;

[0018] S9: Welding two thick wires to the two connecting posts respectively;

[0019] S10: Sealing the substrate with a sealant.

[0020] The beneficial effects of the present invention are as follows: The present invention designs a highly reliable electrical connection method and a unique structure, realizing double connection of the copper electrode with the metal housing mechanically and electrically through a conductive adhesive. The copper electrode uses a soft copper foil or a single-conductor copper strip with lower hardness, and its contact surface with the housing is larger, which can ensure good electrical connection performance of the device in high and low temperature environments. At the same time, the present invention uses sealants, adhesives, etc. to reinforce the overall structure, so that the ultrasonic transducer will not undergo large deformation due to vibration and is resistant to high and low temperatures. In the ultrasonic transducer designed by the present invention, the electrical connection is less affected by the environment and has high reliability. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the ultrasonic transducer in the present invention;

[0022] Figure 2This is a schematic diagram of the connection forms between different copper foils and connection posts in the present invention. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] The present invention provides an ultrasonic transducer and a preparation method thereof. As Figure 1 shown, the method includes: a piezoelectric ceramic sheet 1, a metal housing 2, a fine wire 3, a substrate 4, a sealant 5, a thick wire 6, a connection post 7, a solder joint 8, a conductive adhesive 9, a copper electrode 11, and an acoustic absorption structure 12; two connection posts 7 are provided on the substrate 4, the substrate 4 is arranged on the upper part of the metal housing 2, the negative electrode of the piezoelectric ceramic sheet 1 is adhered to the bottom of the metal housing 2 through the conductive adhesive 9, and the thick wire 6 connects the positive electrode of the piezoelectric ceramic sheet 1 and the first connection post 7; the metal housing 2 is filled with the acoustic absorption structure 12; one end of the copper electrode 11 is welded to the second connection post 7 through the solder joint 8, and the other end of the copper electrode 11 is adhered to the metal housing 2 through the conductive adhesive 9, and each of the first connection post 7 and the second connection post 7 is connected with a fine wire 3; the sealant 5 is coated above the substrate 4 to seal the substrate 4.

[0025] Preferably, a protrusion is provided on the upper part of the inner surface of the metal housing 2, and the substrate 4 is arranged on the protrusion and the substrate 4 is fixed on the protrusion by using an adhesive 10. For the selection of the adhesive, an adhesive with rapid curing, high and low temperature resistance, and moderate hardness after curing can be used. It is necessary to ensure the firmness of the substrate, so that it will not undergo large deformation due to vibration, avoiding the influence on the bonding strength of the conductive adhesive, and it is also necessary that no large stress is generated in high and low temperature environments, also avoiding the influence on the bonding strength of the conductive adhesive, so as to achieve the purpose of the high-reliability electrical connection method of the present invention.

[0026] Preferably, ventilation holes are provided on the substrate 4 to ensure the air pressure balance inside and outside the device.

[0027] Preferably, the copper electrode 11 is a soft copper foil or a single-conductor copper strip. The soft copper foil or the single-conductor copper strip is wrapped around one end of the substrate, and the copper electrode is connected to the housing through the conductive adhesive to achieve double mechanical and electrical connections. The copper electrode and the substrate can be welded at the solder joint by using soldering. As Figure 2 shown, it shows various combination forms of different copper foils and connection posts. Different copper foil sizes can be selected according to different reliability requirements and considerations of operation convenience, and can be connected to the connection posts through different connection methods, such as direct contact or sleeved on the connection post.

[0028] Preferably, the substrate 4 is a PCB board, and the size of the substrate is slightly smaller than that of the metal housing, so that a gap is left between the substrate and the metal housing to just embed the copper electrode.

[0029] The present invention also provides a method for preparing an ultrasonic transducer, including:

[0030] S1: Weld one end of the fine wire to the positive electrode of the piezoelectric ceramic sheet;

[0031] S2: Adhere the negative electrode of the piezoelectric ceramic sheet to the bottom of the metal housing with conductive adhesive;

[0032] S3: Fill the metal housing with an acoustic absorption structure;

[0033] S4: Design and process a substrate with two connecting posts, wrap one end of the copper electrode around the substrate, and weld the other end of the copper electrode to the second connecting post by soldering;

[0034] S5: Weld the other end of the fine wire to the first connecting post;

[0035] S6: Install the substrate into the housing and support it by the protrusion inside the housing to form a stable support state;

[0036] S7: Realize electrical connection between the copper electrode and the housing with conductive adhesive;

[0037] S8: Select a plurality of evenly distributed points at the non-copper electrode positions between the substrate and the housing and fix them with adhesive; Preferably, the adhesive can be selected as epoxy AB adhesive.

[0038] S9: Weld two thick wires to the two connecting posts respectively;

[0039] S10: Seal the substrate with sealant. For the structure with ventilation holes on the substrate, the air holes need to be partially covered during sealing so as to ensure that the ventilation holes are unobstructed to the outside after sealing.

[0040] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention. It should be understood that the above embodiments are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made to the present invention within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An ultrasonic transducer, characterized in that: include: A piezoelectric ceramic sheet (1), a metal shell (2), a thin wire (3), a substrate (4), a sealant (5), a thick wire (6), a connecting column (7), a welding point (8), a conductive glue (9), a copper electrode (11) and a sound absorbing structure (12); the substrate (4) is provided with two connecting columns (7), the substrate (4) is arranged on the upper part of the metal shell (2), the negative electrode of the piezoelectric ceramic sheet (1) is bonded to the bottom of the metal shell (2) through the conductive glue (9), and the thin wire (3) connects the positive electrode of the piezoelectric ceramic sheet (1) and the first connecting column (7); the metal shell (2) is filled with a sound absorbing structure (12); one end of the copper electrode (11) is welded to the second connecting column (7) through the welding point (8), and the other end of the copper electrode (11) is bonded to the metal shell (2) through the conductive glue (9), and the first connecting column (7) and the second connecting column (7) are each connected to a thick wire (6); the sealant (5) is coated on the upper part of the substrate (4) to seal the substrate (4).

2. An ultrasonic transducer according to claim 1, characterized in that: A protrusion is provided on the upper part of the inner surface of the metal shell (2), and the base plate (4) is arranged on the protrusion and the base plate (4) is fixed on the protrusion by using an adhesive (10).

3. An ultrasonic transducer according to claim 1, characterized in that: The substrate (4) is provided with ventilation holes to ensure the balance of air pressure inside and outside the device.

4. The ultrasonic transducer according to claim 1, characterized in that: The copper electrode (11) is a soft copper foil or a single-conducting copper tape.

5. The ultrasonic transducer according to claim 1, characterized in that: The substrate (4) is a PCB board.

6. A method for preparing an ultrasonic transducer, characterized in that: include: S1: Solder one end of the thin wire to the positive electrode of the piezoelectric ceramic; S2: Use conductive glue to bond the negative electrode of the piezoelectric ceramic sheet to the bottom of the metal shell; S3: Filling the metal shell with a sound absorbing structure; S4: Design and process a substrate with two connection pillars, wrap a copper electrode around one end of the substrate, and solder the other end of the copper electrode to the second connection pillar; S5: Solder the other end of the thin wire to the first connecting post; S6: The substrate is installed in the housing and supported by the protrusions inside the housing to form a stable supporting state; S7: Use conductive glue to achieve electrical connection between the copper electrode and the shell; S8: Select multiple evenly distributed points at the non-copper electrode position between the substrate and the shell, and fix them with adhesive; S9: Solder two thick wires to the two connecting posts respectively; S10: Seal the substrate with a sealant.

Images