Hermetically sealed solid electrolyte tantalum capacitor and assembling method thereof

Abstract

The tantalum capacitor comprises a tantalum core and a shell, the tantalum core is arranged in an inner cavity of the shell, an insulating part is arranged at an opening of the inner cavity of the shell, a plug column is arranged between the insulating part in the inner cavity of the shell and the tantalum core, a negative electrode lead is arranged on the shell, and a positive electrode lead is arranged on the shell. And an anode lead is arranged on the insulating part. According to the assembly method, the tantalum core is subjected to preheating treatment, and the tantalum core and the soldering tin are synchronously heated, so that the probability that redundant soldering tin is formed due to the fact that gas in the tantalum core overflows and the soldering tin splashes due to the fact that the temperature difference between the heated and molten assembly bottom tin and the tantalum core is too large in the assembly process can be effectively avoided.

Description

Technical Field

[0001] This invention belongs to the field of capacitor manufacturing technology, and particularly relates to a gas-sealed solid electrolyte tantalum capacitor and its assembly method. Background Technology

[0002] In the field of electronic component manufacturing, hermetically sealed solid tantalum capacitors are a key basic component widely used in aerospace, communication systems, and other scenarios with high reliability requirements. Their production process mainly includes tantalum core pressing, high-temperature sintering, energizing, coating, assembly, and aging screening. Among these, the assembly process is crucial, involving fixing the coated tantalum core into a metal casing and constructing a sealed structure through a reverse process. This directly determines the capacitor's electrical performance and environmental adaptability.

[0003] During assembly, the tantalum core is fixed and sealed using solder material for physical connection and sealing. However, due to the influence of welding process parameters and operational precision, free solder particles may be generated. Although X-ray inspection is used in production to screen for excess solder, some free solder may not be completely removed due to limitations in detection resolution and angle, or operational oversights. These residual excess solder may migrate due to environmental stresses such as vibration and temperature changes during subsequent capacitor testing, transportation, or use. When the length of the free solder reaches 1 / 2 of the inner diameter of the casing, it can easily bridging the positive terminal (tantalum wire) and the negative terminal (metal casing) of the capacitor, causing a polarity short circuit fault and resulting in device failure.

[0004] As electronic devices evolve towards higher reliability, higher demands are placed on the packaging precision and defect control of tantalum capacitors. Excessive solder shadows during X-ray inspection and short circuits caused by ionized solder restrict product yield and reliability. Therefore, in-depth research into the mechanism of excess solder generation, optimization of assembly methods, and prevention of short circuits caused by ionized solder are of great significance for improving the assembly quality of hermetically sealed solid tantalum capacitors and reducing the risk of capacitor short-circuit failure. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a gas-tight solid electrolyte tantalum capacitor and its assembly method.

[0006] The present invention is achieved through the following technical solutions.

[0007] The present invention provides a gas-tight solid electrolyte tantalum capacitor, comprising a tantalum core and a shell. The tantalum core is disposed in the inner cavity of the shell, an insulating element is disposed at the opening of the inner cavity of the shell, a plug is disposed between the insulating element and the tantalum core in the inner cavity of the shell, a negative lead is disposed on the shell, and an anode lead is disposed on the insulating element.

[0008] Preferably, the inner cavity of the outer casing is provided with an assembly layer, and the tantalum core is connected to the inner cavity of the outer casing through the assembly layer.

[0009] Preferably, a connector is provided on the tantalum core, and the connector passes through the plug and the insulating part in sequence before being connected to the anode lead.

[0010] Preferably, the connector is a tantalum wire, the plunger is made of polytetrafluoroethylene, and the insulator is a glass powder insulator.

[0011] Preferably, a valveable tube is provided on the insulating component, and the anode lead extends into the valveable tube and connects to the connector.

[0012] Preferably, a sealing layer is provided between the sidewall of the insulating component and the inner cavity of the outer shell, and a seal is provided at the end of the valve tube.

[0013] Preferably, the sealing layer and the seal are made of tin.

[0014] An assembly method for a gas-tight solid electrolyte tantalum capacitor includes the following steps: Step 1: Weld the tantalum core after film treatment to the connector, and then insert the plug and insulation into the connector; Step 2: Install an assembly layer inside the outer shell cavity; Step 3: Preheat the tantalum core that has undergone Step 1 together with the plug; Step 4: Set the outer shell of the assembly layer for heating, and at the same time, insert the preheated tantalum core along with the plug into the inner cavity of the outer shell for synchronous heating; Step 5: After the assembly layer described in Step 4 has melted, press the tantalum core to the bottom of the inner cavity of the outer shell and shake the tantalum core so that the melted assembly layer evenly coats the tantalum core. Step Six: After completing Step Five, install the corresponding insulating parts according to the size of the outer shell, and adjust the flatness to ensure that the insulating parts are not obviously skewed. Then, set a sealing layer between the insulating parts and the inner cavity of the outer shell. After the sealing layer melts and fills evenly around the insulating parts, transfer the outer shell out of the heating environment for cooling. Step 7: Use solder to encapsulate the valve tube of the insulating component to form a seal, thus giving the capacitor a sealed structure.

[0015] Preferably, the preheating temperature in step three is 80℃~100℃, and the processing time is 20min±5min.

[0016] Preferably, the assembly temperature for inserting the tantalum core into the inner cavity of the outer casing in step four is 200℃~240℃.

[0017] The beneficial effects of this invention are as follows: The assembly method of the present invention, which involves preheating the tantalum core and simultaneously heating the tantalum core and solder, can effectively avoid the probability of excessive solder splashing caused by the large temperature difference between the molten assembly base solder and the tantalum core during the assembly process, which could lead to the overflow of gas inside the tantalum core.

[0018] This invention increases the diameter of the solder wire used for the assembly base and reduces the contact height of one end of the tantalum wire with the inner wall of the casing. This avoids the situation where excess solder adheres to one end of the solder wire after it melts, resulting in a shadow of excess solder during X-ray inspection or loose solder particles falling off during vibration.

[0019] This invention adds insulating material to the cavity between the upper end face of the tantalum core and the insulator, which can effectively isolate the positive terminal inside the capacitor cavity and avoid quality problems such as short circuits caused by soldering of excess material between the positive terminal (tantalum wire) and the negative terminal (metal shell) of the capacitor during testing or use. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the tantalum core structure of the present invention; Figure 3 This is a schematic diagram of the outer casing of the present invention; Figure 4 This is a schematic diagram of the plug structure of the present invention; In the diagram: 1-Tantalum core, 2-Outer shell, 3-Sealing layer, 4-Sealing opening, 5-Anode lead, 6-Negative lead, 7-Assembly layer, 8-Plug, 9-Connector, 10-Insulator, 101-Valveable tube. Detailed Implementation

[0021] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0022] Example 1: like Figures 1 to 4 As shown, a gas-tight solid electrolyte tantalum capacitor includes a tantalum core 1 and a shell 2. The tantalum core 1 is disposed in the inner cavity of the shell 2. An insulating element 10 is disposed at the opening of the inner cavity of the shell 2. A plug 8 is disposed between the insulating element 10 and the tantalum core 1 in the inner cavity of the shell 2. A negative lead 6 is disposed on the shell 2, and an anode lead 5 is disposed on the insulating element 10.

[0023] An assembly layer 7 is provided in the inner cavity of the outer shell 2. The assembly layer 7 is formed by soldering, and the tantalum core 1 is connected to the inner cavity of the outer shell 2 through the assembly layer 7.

[0024] A connector 9 is provided on the tantalum core 1. The connector 9 passes through the plug 8 and the insulating part 10 in sequence and is connected to the anode lead 5.

[0025] The connector 9 is a tantalum wire, and the plunger 8 is made of polytetrafluoroethylene, which has the characteristics of high and low temperature resistance (above -55℃ to 125℃), corrosion resistance, non-toxicity, high insulation and light weight; the insulating component 10 is a glass powder insulator.

[0026] A valveable tube 101 is provided on the insulating component 10, and the anode lead 5 extends into the valveable tube 101 and is connected to the connector 9.

[0027] A sealing layer 3 is provided between the side wall of the insulating component 10 and the inner cavity of the outer shell 2. The sealing layer 3 is formed by soldering, and a seal 4 is provided at the end of the valve tube 101.

[0028] The sealing layer 3 and the seal 4 are made of tin.

[0029] An assembly method for a gas-tight solid electrolyte tantalum capacitor includes the following steps: Step 1: Weld the tantalum core 1 after film treatment to the connector 9, and then insert the plug 8 and the insulator 10 onto the connector 9. The height, outer diameter, inner diameter, etc. of the plug 8 are selected and determined according to the size of the capacitor shell 2, the diameter of the connector 9, the height of the tantalum core 1, etc. Step 2: The outer shell 2 is neatly placed on the tooling fixture, and then the assembly layer 7 is set in the inner cavity of the outer shell 2; Step 3: Place the tantalum core 1, which has undergone the process in Step 1, together with the plug 8 in a metal tray and place it on a heating table for preheating treatment. The preheating temperature is 90℃ and the treatment time is 20min. Step 4: Place the outer shell 2 with the assembly layer 7 into the assembly furnace for heating. At the same time, put the preheated tantalum core 1 along with the plug 8 into the inner cavity of the outer shell 2 for synchronous heating. The assembly temperature of the tantalum core 1 into the inner cavity of the outer shell 2 is 220℃. Step 5: After the assembly layer 7 described in Step 4 has melted, gently press the tantalum core 1 to the bottom of the inner cavity of the outer shell 2, and shake the tantalum core 1 slightly to make the melted assembly layer 7 evenly wrap the tantalum core. Step 6: After completing Step 5, insert the corresponding insulating part 10 according to the size of the outer shell 2, and adjust the flatness so that the insulating part 10 has no obvious skew. Then, set the sealing layer 3 between the insulating part 10 and the inner cavity of the outer shell 2. After the sealing layer 3 melts and is evenly filled around the insulating part 10, transfer the outer shell 2 out of the heating environment for cooling. Step 7: Use solder to encapsulate the valve tube 101 of the insulating component 10 to form a seal 4, thereby giving the capacitor a sealed structure.

[0030] The tantalum core 1 is preheated before assembly to remove the gas inside the tantalum core 1, thereby reducing the probability of solder splashing and forming loose excess solder particles due to the exhaust of the tantalum core 1 during the assembly process.

[0031] Example 2: A gas-tight solid electrolyte tantalum capacitor and its assembly method are disclosed based on Example 1. In the assembly method, the tantalum core 1 is preheated at 80°C for 15 minutes; the assembly temperature of the tantalum core 1 into the inner cavity of the outer casing 2 is 200°C.

[0032] Example 3: A gas-tight solid electrolyte tantalum capacitor and its assembly method are disclosed based on Example 1. In the assembly method, the tantalum core 1 is preheated at 100°C for 25 minutes; the assembly temperature of the tantalum core 1 into the inner cavity of the outer casing 2 is 240°C.

[0033] Comparative Example 1: A gas-tight solid electrolyte tantalum capacitor and its assembly method are disclosed based on Example 1. In the assembly method, the tantalum core 1 is not preheated.

[0034] In Examples 1-3 and Comparative Example 1, the diameter of the outer shell 2 and the diameter of the solder wire used in the assembly layer 7 are shown in the table below.

[0035] The dimensions of the tantalum core 1 used in Examples 1-3 and Comparative Example 1 are shown in the table below.

[0036] The dimensions of the outer casing 2 used in Examples 1-3 and Comparative Example 1 are shown in the table below.

[0037] The dimensions of the plunger 8 used in Examples 1-3 and Comparative Example 1 are shown in the table below.

[0038] The height C of the plunger 8 is designed based on the size H1 of the outer shell 2 and the height H of the tantalum core 1, where C = H1 - H.

[0039] The following table shows the proportion of capacitors that failed high-frequency vibration (monitoring for short circuits when powered on) and X-ray inspection of the capacitors prepared in Examples 1-3 and Comparative Example 1.

[0040] As shown in the table above, increasing the preheating of the tantalum core can effectively reduce the probability of solder splashing during assembly, thereby improving the pass rate of X-ray inspection. At the same time, inserting the plug 8 into the connector 9 can effectively prevent free solder in the cavity from bridging the capacitor connector 9 and the outer shell 2, thus preventing short circuits during testing or use.

Claims

1. A hermetically sealed solid electrolytic tantalum capacitor characterized by: The capacitor comprises a tantalum core (1) and a shell (2), the tantalum core (1) is arranged in the inner cavity of the shell (2), an insulating part (10) is arranged at the opening of the inner cavity of the shell (2), a plug column (8) is arranged between the insulating part (10) and the tantalum core (1) in the inner cavity of the shell (2), a negative lead wire (6) is arranged on the shell (2), and a positive lead wire (5) is arranged on the insulating part (10).

2. A hermetically sealed solid electrolyte tantalum capacitor as defined in claim 1, wherein: An assembly layer (7) is arranged in the inner cavity of the shell (2), and the tantalum core (1) is connected with the inner cavity of the shell (2) through the assembly layer (7).

3. A hermetically sealed solid electrolytic tantalum capacitor as defined in claim 1, wherein: A connecting part (9) is arranged on the tantalum core (1), the connecting part (9) penetrates the plug column (8) and the insulating part (10) in sequence and is connected with the positive lead wire (5).

4. A hermetically sealed solid electrolytic tantalum capacitor as defined in claim 3, characterized by: The connecting part (9) is a tantalum wire, the plug column (8) is made of polytetrafluoroethylene, and the insulating part (10) is a glass powder insulator.

5. A hermetically sealed solid electrolytic tantalum capacitor as defined in claim 3, wherein: A valve pipe (101) is arranged on the insulating part (10), and the positive lead wire (5) is connected with the connecting part (9) by extending into the valve pipe (101).

6. A hermetically sealed solid electrolytic tantalum capacitor as defined in claim 5, characterized by: A sealing layer (3) is arranged between the side wall of the insulating part (10) and the inner cavity of the shell (2), and an end of the valve pipe (101) is provided with a sealing part (4).

7. A hermetically sealed solid electrolytic tantalum capacitor as defined in claim 6, characterized by: The sealing layer (3) and the sealing part (4) are made of tin.

8. A method of assembling a hermetically sealed tantalum solid electrolytic capacitor as defined in claim 7, characterized by, The capacitor comprises the following steps: Step one: the tantalum core (1) after being coated is welded with the connecting part (9), and then the connecting part (9) is penetrated with the plug column (8) and the insulating part (10); Step two: an assembly layer (7) is arranged in the inner cavity of the shell (2); Step three: the tantalum core (1) after step one is preheated together with the plug column (8); Step four: the shell (2) with the assembly layer (7) is heated, and the tantalum core (1) after preheating together with the plug column (8) is loaded into the inner cavity of the shell (2) for synchronous heating; Step five: after the assembly layer (7) in step four is melted, the tantalum core (1) is pressed to the bottom of the inner cavity of the shell (2), and the tantalum core (1) is shaken to make the melted assembly layer (7) uniformly wrap the tantalum core; Step six: after the operation in step five is completed, the corresponding insulating part (10) is penetrated according to the size of the shell (2), and the flatness is adjusted so that the insulating part (10) has no obvious skew phenomenon, then a sealing layer (3) is arranged between the insulating part (10) and the inner cavity of the shell (2), after the sealing layer (3) is melted and uniformly filled around the insulating part (10), the shell (2) is transferred out of the heating environment for cooling; Step seven: the valve pipe (101) of the insulating part (10) is sealed by soldering tin to form a sealing part (4), so that the capacitor has a sealed structure.

9. A method of assembling a hermetically sealed solid electrolytic tantalum capacitor as defined in claim 8, characterized by: In step three, the preheating temperature is 80-100 DEG C, and the processing time is 20 min ± 5 min.

10. A method of assembling a hermetically sealed solid electrolytic tantalum capacitor as defined in claim 8, wherein: In step four, the assembly temperature of the tantalum core (1) loaded into the inner cavity of the shell (2) is 200-240 DEG C.

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