Chip tantalum capacitor and packaging method thereof

Abstract

The invention discloses a chip tantalum capacitor and a packaging method thereof, the capacitor comprises a lead frame and a tantalum core, and the lead frame is connected with the tantalum core through a connecting part. The packaging method comprises the following steps: correspondingly connecting a lead frame, a connecting part and a tantalum core, and then coating a water-soluble polymer material on the connecting part; putting into a mold for mold pressing; soaking in water after mould pressing, taking out, washing and drying; and carrying out electroplating treatment to finish packaging of the tantalum capacitor. According to the invention, a layer of water-soluble polymeric membrane material is coated on the positive and negative electrode lead wire areas of the lead wire frame; the water-soluble polymer material has good adhesion and peelability, so that the epoxy mould pressing flash material can be effectively prevented from being tightly attached to the lead frame in the mould pressing process, the epoxy mould pressing flash material is effectively removed, particularly the flash material is prevented from being tightly attached to the lead frame, the production quality and the product performance are improved, and the production cost is reduced. And the step of treating the flash is omitted.

Description

Technical Field

[0001] The present invention belongs to the technical field of tantalum capacitors, and in particular relates to a chip-type tantalum capacitor and a packaging method thereof. Background Art

[0002] In the field of electronic component manufacturing, chip tantalum capacitors are a common electronic component. Its production process mainly includes tantalum core manufacturing, molded packaging, lead frame processing, and aging. Among them, molding is the process of molding the manufactured tantalum core into a specific shape. Due to the extended service life of the MGP mold, some epoxy resin molding overflows are often generated. These overflows may be a whole piece or a very thin layer, which may be close to the lead frame.

[0003] The existing solution is to perform alkali treatment and sandblasting on the lead frame after molding to remove epoxy resin overflow during molded packaging on the lead frame. The epoxy resin molding overflow is mainly removed by alkali treatment and sandblasting. This method mainly involves first soaking the molding material on the lead frame in an alkaline solution to soften it, and then spraying compressed air containing small steel shots at high speed to make the epoxy molding overflow fall off the lead frame. However, the effect of this method is not ideal, and it is often impossible to completely remove these overflows, and it may cause damage to the lead frame. In severe cases, it causes the lead frame to deform, affecting the quality and mechanical properties of the product.

[0004] In order to solve this problem, the existing technology mainly uses sandblasting to remove these epoxy mold flashes. This method mainly uses high-speed jetting of compressed air containing abrasives to make the epoxy mold flashes fall off the lead frame. However, the effect of this method is not ideal and often cannot completely remove these flashes.

[0005] Secondly, the sandblasting process may damage the lead frame, affecting its service life and reliability. In addition, the sandblasting process will also generate a lot of dust and noise, which will affect the environment and the health of operators. Finally, the alkali treatment process requires the lead frame to be placed in an alkaline solution for high-temperature softening of the molded material. The alkali treatment process may cause the alkaline solution to enter the molded material, which may seriously affect the electrical properties of tantalum capacitors.

[0006] Therefore, how to effectively remove these epoxy molding flashes and improve product quality and performance is an important issue facing current technology.

[0007] The patent document with the announcement number CN117476369A discloses a method for preparing a chip tantalum capacitor with a conductive polymer as a cathode, which includes: coating a polyvinyl alcohol treatment liquid on the surface of the dielectric layer to enhance the adhesion between the dielectric layer and the conductive polymer layer; coating a conductive polymer cathode layer with high conductivity outside the treatment layer; coating the conductive polymer cathode layer with graphite and silver paste to form a graphite layer and a silver paste layer, and leading out the positive and negative electrodes through a lead frame to obtain a tantalum core group, and molding and packaging the tantalum core group to complete the preparation of the chip tantalum capacitor with a conductive polymer as a cathode. However, the patent does not disclose a technical solution for preventing overflow during the capacitor packaging process.

[0008] The patent document with the publication number of US20060221586A1 discloses a packaging substrate with a structure to prevent adhesive overflow, and the packaging substrate includes an array of packaging units. Each packaging unit has a chip pad carrying a chip, a plurality of pins arranged around the chip pad and spaced apart from each other by an open space, and an insulating member filling the open space, and passive components connected between two pins respectively. In addition, an adhesive is applied to the pins connected with the passive components to fix the connection between the passive components and each pin, and a plurality of anti-overflow grooves are respectively arranged around the adhesive on each pin. The passive components are connected to prevent the adhesive from overflowing, and the at least one passive component is a resistor, a capacitor or an inductor. However, the main technical problem solved by the patent is to prevent the adhesive from overflowing during the installation process between the pins of the passive components, and the technical content of anti-overflow in the capacitor packaging process is not disclosed. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a chip-type tantalum capacitor and a packaging method thereof.

[0010] The present invention is achieved through the following technical solutions.

[0011] The present invention provides a chip-type tantalum capacitor, comprising a lead frame and a tantalum core, wherein the lead frame is connected to the tantalum core via a connecting portion.

[0012] Preferably, through hole A, through hole B and spacers are provided on the lead frame, a plurality of tantalum cores are provided, the tantalum core is provided between two spacers, the through hole A is provided on one side of the lead frame, and the through hole B is provided on the other side of the lead frame.

[0013] Preferably, a groove A and a groove B are provided on the lead frame, the groove A is symmetrically arranged on both sides of the lead frame, the groove B is arranged at the corners of the lead frame, and the spacer is connected to the tantalum core through a connecting sheet.

[0014] A packaging method for a chip tantalum capacitor comprises the following steps:

[0015] S1: After the lead frame, the connection part and the tantalum core are connected correspondingly, a water-soluble polymer material is coated on the connection part;

[0016] S2: Place in a mold for molding;

[0017] S3: Soak the molded parts in water, take them out, rinse them and dry them;

[0018] S4: Perform electroplating to complete the packaging of the tantalum capacitor.

[0019] Preferably, in step S1, a water-soluble polymer material is coated on the connection portion between the tantalum core and the positive and negative electrode regions of the lead frame, and the thickness of the coated water-soluble polymer material is 0.05-0.5 mm.

[0020] Preferably, the water-soluble polymer material includes one or more of carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl alcohol, and polyethylene glycol.

[0021] Preferably, in step S2, the molding pressure is 1.5-2.5 MPa, the temperature is 150-200° C., and the time is 10-20 min.

[0022] Preferably, in step S3, after molding, the molded product is immersed in water at 50-80° C. for 5-30 minutes, taken out, rinsed, and dried in a forced air drying oven.

[0023] Preferably, in step S3, the drying temperature is 65-85° C., and the drying time is 5-15 min.

[0024] Preferably, the electroplating material in step S4 is tin-lead, the electroplating time is 10-30 min, and the current density is 2-5 A / dm 2 .

[0025] The beneficial effects of the present invention are:

[0026] The present invention coats a layer of water-soluble polymer film material on the positive and negative lead areas of the lead frame. Since the water-soluble polymer material has good adhesion and strippability, it can effectively prevent epoxy molding overflow from clinging to the lead frame during the molding process, effectively remove the epoxy molding overflow, especially avoid the overflow from clinging to the lead frame, thereby improving the production quality and product performance and eliminating the step of processing the overflow.

[0027] In the process of the present invention, if overflow occurs, it will fall onto the connecting portion. By arranging a water-soluble polymer layer at the connecting portion, the water-soluble polymer layer will dissolve when immersed in water or other solvents, and the overflow will easily fall off. There is no need to perform alkali treatment, manual deburring or other steps to remove the overflow, thereby ensuring the quality of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the present invention;

[0029] In the figure: 1-lead frame, 2-connecting part, 3-tantalum core, 4-through hole A, 5-through hole B, 6-spacer, 7-groove A, 8-groove B, 9-connecting piece. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0031] Embodiment 1:

[0032] like Figure 1 As shown, a chip-type tantalum capacitor comprises an iron-nickel lead frame 1 and a tantalum core 3 , wherein the lead frame 1 is connected to the tantalum core 3 via a connecting portion 2 .

[0033] The lead frame 1 is provided with a through hole A4, a through hole B5 and a spacer 6. A plurality of tantalum cores 3 are provided. The tantalum core 3 is provided between two spacers 6. The through hole A4 is provided on one side of the lead frame 1, and the through hole B5 is provided on the other side of the lead frame 1.

[0034] The lead frame 1 is provided with a groove A7 and a groove B8, wherein the groove A7 is symmetrically arranged on both sides of the lead frame 1, and the groove B8 is arranged at the corners of the lead frame 1, and the spacer 6 is connected to the tantalum core 3 via a connecting piece 9. Among them, the through hole A4, the through hole B5, the groove A7 and the groove B8 are arranged to adapt to the subsequent installation and use environment of the capacitor.

[0035] A packaging method for a chip tantalum capacitor comprises the following steps:

[0036] S1: After the lead frame 1, the connection part 2 and the tantalum core 3 are connected correspondingly, a water-soluble polymer material is coated on the connection part 2 between the tantalum core 3 and the positive and negative electrode areas of the lead frame 1;

[0037] S2: Place the capacitor into a mold for molding;

[0038] S3: Soak the molded parts in water, take them out, rinse them and dry them;

[0039] S4: Perform electroplating to complete the packaging of the tantalum capacitor.

[0040] In the step S1, a water-soluble polymer material is coated on the connection portion 2 between the tantalum core 3 and the positive and negative electrode regions of the lead frame 1, and the thickness of the coated water-soluble polymer material is 0.05 mm.

[0041] The water-soluble polymer material includes carboxymethyl cellulose and polyvinyl pyrrolidone.

[0042] In step S2, the molding pressure is 1.5 MPa, the temperature is 150° C., and the time is 10 min.

[0043] In the step S3, after molding, the molded product is immersed in 50° C. water for 5 minutes, taken out, rinsed, and dried in a forced air drying oven.

[0044] In step S3, the drying temperature is 65° C. and the drying time is 5 min.

[0045] The electroplating material in step S4 is tin-lead, the electroplating time is 10 minutes, and the current density is 2A / dm 2 .

[0046] Embodiment 2:

[0047] like Figure 1 As shown, a chip-type tantalum capacitor comprises a lead frame 1 and a tantalum core 3 , wherein the lead frame 1 is connected to the tantalum core 3 via a connecting portion 2 .

[0048] The lead frame 1 is provided with a through hole A4, a through hole B5 and a spacer 6. A plurality of tantalum cores 3 are provided. The tantalum core 3 is provided between two spacers 6. The through hole A4 is provided on one side of the lead frame 1, and the through hole B5 is provided on the other side of the lead frame 1.

[0049] The lead frame 1 is provided with a groove A7 and a groove B8, wherein the groove A7 is symmetrically arranged on both sides of the lead frame 1, and the groove B8 is arranged at the corners of the lead frame 1, and the spacer 6 is connected to the tantalum core 3 via a connecting piece 9. Among them, the through hole A4, the through hole B5, the groove A7 and the groove B8 are arranged to adapt to the subsequent installation and use environment of the capacitor.

[0050] A packaging method for a chip tantalum capacitor comprises the following steps:

[0051] S1: After the lead frame 1, the connection part 2 and the tantalum core 3 are connected correspondingly, a water-soluble polymer material is coated on the connection part 2 between the tantalum core 3 and the positive and negative electrode areas of the lead frame 1;

[0052] S2: Place the capacitor into a mold for molding;

[0053] S3: Soak the molded parts in water, take them out, rinse them and dry them;

[0054] S4: Perform electroplating to complete the packaging of the tantalum capacitor.

[0055] In the step S1, a water-soluble polymer material is coated on the connection portion 2 between the tantalum core 3 and the positive and negative electrode regions of the iron-nickel lead frame 1, and the thickness of the coated water-soluble polymer material is 0.5 mm.

[0056] The water-soluble polymer material includes polyvinyl alcohol and polyethylene glycol.

[0057] In step S2, the molding pressure is 2.5 MPa, the temperature is 200° C., and the time is 20 min.

[0058] In the step S3, after molding, the molded product is immersed in 80° C. water for 30 minutes, taken out, rinsed, and dried in a forced air drying oven.

[0059] In step S3, the drying temperature is 85° C. and the drying time is 15 min.

[0060] The electroplating material in step S4 is tin-lead, the electroplating time is 30 minutes, and the current density is 5A / dm 2 .

[0061] Embodiment 3:

[0062] like Figure 1 As shown, a chip-type tantalum capacitor comprises a lead frame 1 and a tantalum core 3 , wherein the lead frame 1 is connected to the tantalum core 3 via a connecting portion 2 .

[0063] The lead frame 1 is provided with a through hole A4, a through hole B5 and a spacer 6. A plurality of tantalum cores 3 are provided. The tantalum core 3 is provided between two spacers 6. The through hole A4 is provided on one side of the lead frame 1, and the through hole B5 is provided on the other side of the lead frame 1.

[0064] The lead frame 1 is provided with a groove A7 and a groove B8, wherein the groove A7 is symmetrically arranged on both sides of the lead frame 1, and the groove B8 is arranged at the corners of the lead frame 1, and the spacer 6 is connected to the tantalum core 3 via a connecting piece 9. Among them, the through hole A4, the through hole B5, the groove A7 and the groove B8 are arranged to adapt to the subsequent installation and use environment of the capacitor.

[0065] A packaging method for a chip tantalum capacitor comprises the following steps:

[0066] S1: After the lead frame 1, the connection part 2 and the tantalum core 3 are connected correspondingly, a water-soluble polymer material is coated on the connection part 2 between the tantalum core 3 and the positive and negative electrode areas of the lead frame 1;

[0067] S2: Place the capacitor into the mold for molding;

[0068] S3: Soak the molded parts in water, take them out, rinse them and dry them;

[0069] S4: Perform electroplating to complete the packaging of the tantalum capacitor.

[0070] In the step S1, a water-soluble polymer material is coated on the connection portion 2 between the tantalum core 3 and the positive and negative electrode regions of the iron-nickel lead frame 1, and the thickness of the coated water-soluble polymer material is 0.2 mm.

[0071] The water-soluble polymer material is polyvinyl pyrrolidone.

[0072] In step S2, the molding pressure is 2 MPa, the temperature is 180° C., and the time is 16 min.

[0073] In the step S3, after molding, the molded product is immersed in 67° C. water for 19 minutes, taken out, rinsed, and dried in a forced air drying oven.

[0074] In step S3, the drying temperature is 76° C. and the drying time is 10 min.

[0075] The electroplating material in step S4 is tin-lead, the electroplating time is 21 minutes, and the current density is 3.5A / dm 2 .

[0076] Comparative Example 1:

[0077] There are 16V 100μF capacitors available.

[0078] The 16V 100μF capacitor was prepared by the methods of Examples 1 and 3, and the molding was completed at pressures of 1.5Mpa, 2Mpa, and 2.5Mpa, respectively. The subsequent processes were processed according to the processes of Examples 1-3. The electrical properties of the terminal processing products of the existing 16V 100μF capacitor production process in Comparative Example 1 are compared as shown in Table 1 below:

[0079] Table 1 Electrical performance parameter comparison table

[0080]

[0081]

[0082] From the electrical properties in Table 1, it can be seen that the low pressure in comparative example 1 cannot ensure complete sealing under conventional processes, and the high pressure has too much impact on the tantalum core, affecting the electrical properties. The data of Examples 1-3 show that under a certain pressure, without immersion in alkaline solution, the leakage current of the tantalum core is very friendly.

Claims

1. A chip tantalum capacitor, characterized in that: The invention comprises a lead frame (1) and a tantalum core (3), wherein the lead frame (1) is connected to the tantalum core (3) via a connecting portion (2).

2. A chip tantalum capacitor according to claim 1, characterized in that: The lead frame (1) is provided with a through hole A (4), a through hole B (5) and a spacer (6); a plurality of tantalum cores (3) are provided, and the tantalum core (3) is provided between two spacers (6); the through hole A (4) is provided on one side of the lead frame (1), and the through hole B (5) is provided on the other side of the lead frame (1).

3. A chip tantalum capacitor as claimed in claim 2, characterized in that: The lead frame (1) is provided with a groove A (7) and a groove B (8), wherein the groove A (7) is symmetrically arranged on both sides of the lead frame (1), and the groove B (8) is arranged at the corner of the lead frame (1), and the spacer (6) is connected to the tantalum core (3) via a connecting piece (9).

4. A packaging method for a chip tantalum capacitor according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: After the lead frame (1), the connection part (2) and the tantalum core (3) are connected correspondingly, a water-soluble polymer material is coated on the connection part (2); S2: Place in a mold for molding; S3: Soak the molded parts in water, take them out, rinse them and dry them; S4: Perform electroplating to complete the packaging of the tantalum capacitor.

5. The packaging method of a chip tantalum capacitor according to claim 4, characterized in that: In the step S1, a water-soluble polymer material is coated on the connection portion (2) between the tantalum core (3) and the positive and negative electrode regions of the lead frame (1), and the thickness of the coated water-soluble polymer material is 0.05-0.5 mm.

6. The packaging method of a chip tantalum capacitor according to claim 4, characterized in that: The water-soluble polymer material includes one or more of carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene glycol.

7. The packaging method of a chip tantalum capacitor according to claim 4, characterized in that: In step S2, the molding pressure is 1.5-2.5 MPa, the temperature is 150-200° C., and the time is 10-20 min.

8. The packaging method of a chip tantalum capacitor according to claim 4, characterized in that: In the step S3, after molding, the molded product is placed in 50-80° C. water and soaked for 5-30 minutes, taken out and rinsed, and placed in a blast drying oven for drying.

9. The packaging method of a chip tantalum capacitor according to claim 4, characterized in that: In step S3, the drying temperature is 65-85° C. and the drying time is 5-15 min.

10. The packaging method of a chip tantalum capacitor according to claim 4, characterized in that: The electroplating material in step S4 is tin-lead, the electroplating time is 10-30 minutes, and the current density is 2-5A / dm 2 .

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