Tantalum capacitor with truncated cone-shaped bottom structure

Abstract

The utility model discloses a tantalum capacitor with a circular truncated cone-shaped bottom structure, which belongs to the technical field of tantalum capacitors and comprises a copper shell, an anode lead, a cathode lead, an insulator, a tantalum anode block and an insulating sleeve, the cathode lead is connected with a closed end of the copper shell to form a cathode whole, and the tantalum anode block is arranged inside the copper shell. The end, close to the negative lead, of the tantalum anode block is of a circular-truncated-cone-shaped structure, the insulator is arranged at the open end of the copper shell, the positive lead is led out of the open end of the tantalum anode block and penetrates through the insulator, and the insulating sleeve is arranged outside the copper shell in a sleeving mode. The negative electrode leading-out end of the tantalum anode block is of a circular truncated cone-shaped structure, so that the tail end can be prevented from being subjected to reverse friction in the demolding process of a tantalum anode block core strip under the structure, and the bottom structure is prevented from being stressed and loosened. The lower ends of the tantalum powder and the tantalum strip are pressed more tightly when the tantalum powder and the tantalum strip are pressed in a mold through the circular truncated cone-shaped structure, the problem that the tantalum core density is not uniform is solved to a certain extent, and therefore the strength of the tantalum anode block and a formed oxidation film are more uniform.

Description

Technical Field

[0001] The utility model belongs to the technical field of tantalum capacitors, in particular to a tantalum capacitor with a truncated cone bottom structure. Background Art

[0002] As a key component in electronic devices, solid tantalum capacitors offer exceptional electrical properties and a long service life, enabling them to demonstrate superior performance in a wide range of applications. The core structure of a tantalum capacitor consists of a tantalum anode core, a polymer cathode, a tantalum pentoxide film, and a housing. The tantalum anode is the primary active component of the capacitor, while the tantalum pentoxide film acts as an insulating dielectric. The housing provides protection and conducts electricity, forming a negative electrode with the internal cathode. The positive lead is connected to the external circuit.

[0003] The traditional production process for solid tantalum capacitors typically uses unidirectional manual pressing. This method presents some potential problems during the manufacturing process, especially during the production aging test phase, which can easily lead to breakdown failure at the bottom of the negative electrode. This failure mode is usually caused by the combined action of multiple factors, mainly manifested in the following aspects: 1. During the manual pressing process, due to uneven pressure distribution, the density of the tantalum anode block varies greatly in various areas, especially the bottom, which is often less dense. This directly leads to insufficient mechanical strength at the bottom; 2. After pressing and forming, if the demolding process of the tantalum anode block is not properly controlled, it may cause secondary friction and damage the surface of the tantalum anode block, especially in the bottom area. Therefore, when the capacitor is in long-term operation or under high-voltage conditions, the anode material at the bottom is more susceptible to damage, the pressure resistance is reduced, and failure occurs. Utility Model Content

[0004] The purpose of the present utility model is to provide a tantalum capacitor with a truncated cone bottom structure to solve the problems mentioned above in the prior art.

[0005] A tantalum capacitor with a truncated cone bottom structure is provided, comprising:

[0006] A copper shell, a positive lead, a negative lead, an insulator, a tantalum anode block and an insulating sleeve. The negative lead is connected to the closed end of the copper shell to form a cathode as a whole. The tantalum anode block is arranged inside the copper shell. The end of the tantalum anode block close to the negative lead is a truncated cone structure. The insulator is arranged at the open end of the copper shell. The positive lead is led out from the open end of the tantalum anode block and passes through the insulator. The insulating sleeve is sleeved on the outside of the copper shell.

[0007] Furthermore, the truncated cone structure of the tantalum anode block and the copper shell are fixed by molten tin.

[0008] Furthermore, the copper shell and the insulator are fixedly connected by laser welding.

[0009] Furthermore, the copper shell and the insulator are sealed by soldering.

[0010] Furthermore, the connection portion between the insulator and the positive lead is insulated by glass.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] The negative terminal of the tantalum anode block is formed into a truncated cone shape using a special mold. This structure prevents the tail end of the tantalum anode core from being subjected to reverse friction during demolding, which could cause the bottom structure to loosen under stress. Furthermore, the unique truncated cone shape allows the tantalum powder to be pressed more tightly at the bottom during pressing in the mold, to some extent solving the problem of tantalum core density increasing at the top and decreasing at the bottom during unidirectional pressing. This results in more uniform strength of the tantalum anode block and a more evenly distributed oxide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0014] Figure 1 This is a schematic diagram of the overall structure of a tantalum capacitor with a truncated cone bottom structure.

[0015] In the figure: 1. Copper shell; 2. Positive lead; 3. Negative lead; 4. Insulator; 5. Tantalum anode block; 6. Insulating sleeve. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts are within the scope of protection of this application.

[0017] Obviously, the drawings described below are merely examples or embodiments of the present application. Those skilled in the art can, without inventive effort, apply the present application to other similar scenarios based on these drawings. Furthermore, it is also understood that, although the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, changes in design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as an insufficiency of the content disclosed in this application.

[0018] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of substantially identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided to facilitate a thorough understanding of this application by those skilled in the art and are not intended to limit the subject matter recited in the claims.

[0019] See also Figure 1 As shown, in an embodiment of the present invention, a tantalum capacitor with a truncated cone bottom structure includes a copper shell 1, a positive lead 2, a negative lead 3, an insulator 4, a tantalum anode block 5 and an insulating sleeve 6. The negative lead 3 is connected to the closed end of the copper shell 1 to form a cathode as a whole. The tantalum anode block 5 is arranged inside the copper shell 1. The end of the tantalum anode block 5 close to the negative lead 3 is a truncated cone structure. The insulator 4 is arranged at the open end of the copper shell 1. The positive lead 2 is led out from the open end of the tantalum anode block 5 and passes through the insulator 4. The insulating sleeve 6 is sleeved on the outside of the copper shell 1.

[0020] Prepare a special mold with a truncated cone-shaped groove at the bottom, and press high-specific-capacity tantalum powder and tantalum wire into a tantalum anode block 5 with a truncated cone-shaped bottom structure and lead wires in the special mold. After sintering and energizing, it is used as a positive electrode core block. The tantalum anode block 5 is placed in the copper shell 1. The copper shell 1 is divided into an open end and a closed end. The truncated cone-shaped structure of the tantalum anode block 5 faces the closed end of the copper shell 1. The negative lead 3 is fixed to the outside of the closed end of the copper shell 1 and fixed to the connection with the copper shell 1 by welding. After one end of the positive lead 2 is fixed to the tantalum anode block 5, the other end passes through the insulator 4, and the insulator 4 covers the open end of the copper shell 1. The insulating sleeve 6 is integrally mounted on the outside of the copper shell 1 for insulation protection.

[0021] The frustoconical bottom structure of the tantalum anode block 5 protects the tantalum core from reverse friction and collision with the mold during demolding, thus preventing damage to the tail end of the tantalum anode block 5 and even invisible cracks, effectively protecting the oxide film on the surface of the tantalum anode block 5. This structure also reduces the reverse force acting on the tantalum anode block 5 during demolding, making the demolding process smoother.

[0022] When the tantalum powder is placed in the mold and pressed, the truncated cone-shaped groove at the bottom of the mold improves the compaction of this portion of the tantalum powder. The truncated cone's inclined surface not only exerts axial pressure on the tantalum powder but also radial pressure, ensuring a tighter compaction of the powder. The resulting tantalum anode block 5, after sintering, has a more uniform strength.

[0023] When the tantalum anode block 5 is assembled with the copper shell 1 , a tin bar is melted at the inner bottom of the copper shell 1 , and the truncated cone structure of the tantalum anode block 5 is fixed to the copper shell 1 by the molten tin, thereby fixing the copper shell 1 and the tantalum anode block 5 .

[0024] The copper housing 1 and insulator 4 are securely connected via laser welding. Laser welding is suitable for metal-to-metal connections and provides precise welding, ensuring the copper housing 1's airtightness and moisture resistance, protecting the capacitor's internal electronic components from environmental influences. Laser welding provides high energy density, allowing precise control of heat input to avoid damage to other parts of the capacitor. After welding, the copper housing 1 and insulator 4 are sealed with solder, which prevents moisture, dust, and other contaminants from entering the capacitor, ensuring a good airtight seal.

[0025] The connection between insulator 4 and positive lead 2 is insulated with glass. Heating the glass to its softening point causes it to melt between the positive lead 2 and insulator 4. Upon cooling, the glass solidifies, forming a strong, airtight package that prevents the intrusion of moisture and oxygen, extending the life of the capacitor. The glass's high electrical insulation properties effectively prevent electrical short circuits and current leakage.

[0026] Example 1

[0027] This embodiment provides a tantalum capacitor, including a copper shell 1 , a positive lead 2 , a negative lead 3 , an insulator 4 , a tantalum core, and an insulating sleeve 6 .

[0028] The tantalum core is subjected to an electrochemical oxidation process to form a tantalum pentoxide oxide film on the tantalum anode block 5;

[0029] The tantalum anode block 5 is pressed into a tantalum core with a truncated cone bottom structure using a special mold;

[0030] The cathode is composed of a copper shell 1, a negative electrode lead 3, and PEDOT material (poly (3,4-ethylenedioxythiophene).

[0031] Comparative Example 1

[0032] The difference between Comparative Example 1 and Example 1 is that the tantalum anode block 2 is pressed into a tantalum core with a cylindrical bottom structure using a conventional mold.

[0033] The performance test results of Example 1 and Comparative Example 1 of the present application are shown in Table 1.

[0034] Table 1

[0035] - Leakage current (μA) Yield (%) Example 1 8 96.7 Comparative Example 1 24 91.3

[0036] Example 1: Regarding Comparative Example 1, a tantalum core with a truncated cone bottom structure was pressed using a specialized mold. This structure prevents the tail end from being subjected to reverse friction during demolding, which could cause the bottom structure to loosen under stress. Furthermore, the unique truncated cone structure allows for a tighter fit at the bottom, partially resolving the problem of tantalum core density being higher at the top and lower at the bottom when using unidirectional pressing. This results in more uniform tantalum anode strength and a more evenly distributed oxide film.

[0037] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present application, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A tantalum capacitor with a truncated cone bottom structure, characterized in that: include: A copper shell (1), a positive lead (2), a negative lead (3), an insulator (4), a tantalum anode block (5) and an insulating sleeve (6); the negative lead (3) is connected to the closed end of the copper shell (1) to form a cathode as a whole; the tantalum anode block (5) is arranged inside the copper shell (1); one end of the tantalum anode block (5) close to the negative lead (3) is a truncated cone structure; the insulator (4) is arranged at the open end of the copper shell (1); the positive lead (2) is led out from the open end of the tantalum anode block (5) and passes through the insulator (4); and the insulating sleeve (6) is sleeved on the outside of the copper shell (1).

2. The tantalum capacitor with a truncated cone bottom structure according to claim 1, characterized in that: The truncated cone-shaped structure of the tantalum anode block (5) is fixed to the copper shell (1) by molten tin.

3. The tantalum capacitor with a truncated cone bottom structure according to claim 1, characterized in that: The copper shell (1) and the insulator (4) are fixedly connected by laser welding.

4. The tantalum capacitor with a truncated cone bottom structure according to claim 3, characterized in that: The copper shell (1) and the insulator (4) are sealed by soldering.

5. The tantalum capacitor with a truncated cone bottom structure according to claim 1, characterized in that: The connection portion between the insulator (4) and the positive electrode lead (2) is insulated by glass.

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