Capacitor with reduced tantalum capacitance degradation and method of manufacture

Abstract

The application discloses a capacitor for reducing tantalum capacity attenuation and a preparation method thereof, and comprises the following steps: tantalum powder is prepared into a tantalum block; the tantalum block is sintered; a forming process is conducted on the tantalum block to obtain a tantalum core with a dielectric oxide film; the tantalum core with the dielectric oxide film is subjected to an immersion treatment, and then the tantalum core is packaged; and after the packaged tantalum core is aged, the preparation of the capacitor is completed. In the forming process, a gradient boosting forming method is adopted to improve the forming voltage ratio of the tantalum core, and a Ta2O5 dielectric oxide film with good performance is obtained; a polarizing agent is added in a working electrolyte during assembly to inhibit the generation of hydrogen in the product, reduce the internal gas pressure release of the capacitor, and stabilize the capacity; and through adjustment of an aging process, a high-voltage, large-capacity non-solid electrolyte tantalum capacitor is manufactured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of capacitors, and particularly relates to a capacitor for reducing the attenuation of the capacitance of a tantalum capacitor and a preparation method thereof. BACKGROUND

[0002] Product lightening and miniaturization have been the goal pursued by the market and suppliers, and the demand of users for high-voltage large-capacity small-size liquid tantalum products is also increasingly urgent. With the continuous deepening of research on materials and process technology, the process technology requirements for the production of liquid tantalum products are also increasingly high. At present, domestic and foreign manufacturers have developed large-capacity small-size products, but many small-size large-capacity capacitors produced by the conventional process, especially those with high technical difficulty, will have the problem of capacitance attenuation after electrical aging life, so a capacitor preparation method is needed to solve this problem.

[0003] The patent document with the publication number CN104916443A discloses a high-voltage sheet type conductive polymer solid electrolyte tantalum capacitor and a manufacturing method thereof. The method comprises: pressing sheet type tantalum powder raw materials into a tantalum core blank block with a tantalum wire lead-out line, vacuum sintering the tantalum core blank block, and then performing passivation treatment; placing the sintered blank block into a forming tank containing an ethylene glycol phosphate electrolyte to electrochemically form a dielectric layer with a thickness of not less than 3000 nanometers or 3500 nanometers; using a repeated immersion method to penetrate the nanoscale poly 3,4 ethylene dioxythiophene particle solution into the internal gap and the dielectric layer of the blank block to deposit and form a cathode on the dielectric layer, and coating a graphite layer and a silver paste layer on the cathode as a cathode lead-out layer; welding the tantalum wire lead-out line of the blank block to the metal frame lead of the shell, and packaging with epoxy resin to obtain the high-voltage sheet type conductive polymer solid electrolyte tantalum capacitor. However, the rated withstand voltage and leakage current of the sheet type solid tantalum electrolytic capacitor prepared by the patent can reach 50V or 63V, and the loss of the capacitance of the capacitor after aging is not solved. SUMMARY

[0004] To solve the above technical problems, the application provides a capacitor for reducing the attenuation of the capacitance of a tantalum capacitor and a preparation method thereof.

[0005] The application is implemented by the following technical solutions.

[0006] The application provides a preparation method of a capacitor for reducing the attenuation of the capacitance of a tantalum capacitor, which comprises the following steps:

[0007] S1: preparing tantalum powder into a tantalum block;

[0008] S2: sintering the tantalum block;

[0009] S3: performing a forming process on the tantalum block to obtain a tantalum core with a dielectric oxide film;

[0010] S4: the tantalum core with dielectric oxide film is immersed and treated, and then the tantalum core is packaged;

[0011] S5: the capacitor is prepared after the packaged tantalum core is aged.

[0012] Preferably, the tantalum powder with a specific capacitance of 15000 μFV / g in the step S1 is formed by using a lubricant-added forming die, and the anode tantalum block is obtained after slow demolding.

[0013] Preferably, the sintering temperature in the step S2 is 1500-1700 ℃, and the temperature is kept for 30-50 min after reaching the temperature, and the furnace is taken out after cooling to 30 ℃, so as to ensure that the specific capacitance of the tantalum core after sintering is 13500-15500 μFV / g.

[0014] Preferably, the forming process in the step S3 is a voltage segment voltage boosting forming process, and the steps include, in sequence, a forming step A, a forming step B, a heat treatment, a supplement forming, and a boiling washing.

[0015] Preferably, the forming liquid used in the forming process is ethylene glycol phosphate, and the forming step A includes: soaking at a temperature of 86-89 ℃, and the soaking time is: 1-3 h of uncharged soaking and 0.5-2 h of soaking under the application of a 3 V voltage.

[0016] Preferably, the forming step B includes: constant voltage for 4-9 h in each stage under current densities in sequence of: 0-60 V, 0.08 nCV / 100 mA; 60-90 V, 0.06 nCV / 100 mA; and 90-142 V, 0.04 nCV / 100 mA.

[0017] The heat treatment includes: keeping at 300-400 ℃ for 20-45 min.

[0018] Preferably, the supplement forming step includes: constant voltage for 10-40 min at 75-85 V; constant voltage for 10-40 min at 86-95 V; constant voltage for 10-40 min at 96-105 V; constant voltage for 10-40 min at 106-115 V; constant voltage for 10-40 min at 116-125 V; constant voltage for 10-40 min at 126-135 V; and constant voltage for 10-40 min at 136-145 V.

[0019] Preferably, the boiling washing step includes boiling washing in deionized water at a temperature of 100-125 ℃ for 30-35 min, and the boiling washing is repeated for six to seven times, and the prepared tantalum core with good dielectric oxide film is obtained after taking out and drying for 3-3.5 h.

[0020] Preferably, the step S4 of the impregnation treatment step comprises: impregnating the tantalum core with a medium oxide film using sulfuric acid electrolyte for 0.5-2h, assembling using electrolyte added with a compound polarizer composed of sulfate ions and metal cations, and then tin solder packaging.

[0021] Preferably, the step S5 of the aging step of the packaged tantalum core comprises the following steps in sequence: maintaining at room temperature and 1-6V for 1-3h; then maintaining at room temperature and 60-90V for 4-8h; then maintaining at 55-75℃ and 60-90V for 4-8h; then maintaining at 110-140℃ and 40-70V for 1-4h; then maintaining at 75-95℃ and 60-90V for 40-55h; and the voltage rising speed is 2-7V / 20min.

[0022] A capacitor prepared by the above method.

[0023] The present application has the following advantages:

[0024] The present application adopts the gradient voltage rising forming method in the forming process, improves the voltage ratio of the tantalum core, and obtains a Ta2O5 medium oxide film with good performance; the polarizer is added in the working electrolyte during the assembling, the generation of hydrogen in the product is inhibited, the internal pressure release of the capacitor is reduced, and the capacity is stabilized; and the adjustment of the aging process method is further made, thereby manufacturing a high-voltage and large-capacity non-solid electrolytic tantalum capacitor. DETAILED DESCRIPTION

[0025] The technical solutions of the present application are further described below, but the scope of protection is not limited to the description.

[0026] Example 1:

[0027] A preparation method of a capacitor for reducing the capacity attenuation of a tantalum capacitor, comprising the following steps:

[0028] S1: preparing tantalum powder into a tantalum block;

[0029] S2: sintering the tantalum block;

[0030] S3: performing a forming process on the tantalum block to obtain a tantalum core with a medium oxide film;

[0031] S4: performing an impregnation treatment on the tantalum core with the medium oxide film, and then packaging the tantalum core;

[0032] S5: completing the preparation of the capacitor after aging the packaged tantalum core.

[0033] The tantalum powder with specific volume of 15000 μFV / g in step S1 is accurately weighed by using an electronic analytical balance, and is formed by using a φ14.2 forming die with hard stearic acid as lubricant, and a certain strength of anode tantalum block is obtained after slow demolding.

[0034] The sintering temperature in step S2 is 1500℃, and the temperature is kept for 30 min after reaching the temperature, and the furnace is taken out after cooling to 30℃, so as to ensure that the specific volume of the tantalum powder after sintering is 13500 μFV / g.

[0035] The forming process in step S3 is voltage stage voltage increasing forming, and the steps include forming step A, forming step B, heat treatment, supplement forming and boiling washing.

[0036] The forming liquid used in the forming process is ethylene glycol phosphate, and the forming step A includes soaking at a temperature of 86℃, and soaking time: uncharged soaking for 1 h, and then soaking under the application of 3V voltage for 0.5 h.

[0037] The forming step B includes: under the current density of 0V, 0.08nCV / 100mA; 60V, 0.06nCV / 100mA; 90V, 0.04nCV / 100mA, respectively, each stage is kept for 4 h under constant voltage;

[0038] The heat treatment includes keeping at 300℃ for 20 min.

[0039] The supplement forming step includes: keeping constant voltage for 10 min under 75V; keeping constant voltage for 10 min under 86V; keeping constant voltage for 10 min under 96V; keeping constant voltage for 10 min under 106V; keeping constant voltage for 10 min under 116V; keeping constant voltage for 10 min under 126V; keeping constant voltage for 10 min under 136V.

[0040] The boiling washing step includes boiling washing in deionized water at a temperature of 100℃ for 30 min, and the boiling washing is repeated for six times, and the tantalum core with good Ta2O5 dielectric oxide film is prepared after taking out and drying for 3 h.

[0041] The soaking treatment step in step S4 includes: soaking treatment of the tantalum core with Ta2O5 dielectric oxide film by using sulfuric acid electrolyte for 0.5 h, assembling by using electrolyte added with iron sulfate polarizer, and then tin soldering packaging by using conventional packaging mode, and the soaking treatment and packaging can be conventional steps.

[0042] The aging step of the packaged tantalum core in step S5 includes: keeping at room temperature and 1V for 1 h; then keeping at room temperature and 60V for 4 h; then keeping at 55℃ and 60V for 4 h; then keeping at 110℃ and 40V for 1 h; then keeping at 75℃ and 60V for 40 h; and the voltage increasing speed is 2V / 20 min.

[0043] Embodiment 2

[0044] A preparation method of a tantalum capacitor with reduced capacitance attenuation, comprising the following steps:

[0045] S1: preparing tantalum powder into a tantalum block;

[0046] S2: sintering the tantalum block;

[0047] S3: forming process on the tantalum block to obtain a tantalum core with a dielectric oxide film;

[0048] S4: immersing the tantalum core with the dielectric oxide film and then packaging the tantalum core;

[0049] S5: aging the packaged tantalum core and then completing the preparation of the capacitor.

[0050] In the step S1, 22300 mg of tantalum powder with a specific capacity of 15000 μFV / g is accurately weighed by using an electronic analytical balance, and is formed by using a φ14.2 forming die with hard stearic acid as a lubricant, and a certain strength of an anode tantalum block is obtained after slow demolding.

[0051] In the step S2, the sintering temperature is 1700℃, and after reaching the temperature, it is kept for 50 min, and after cooling to 30℃, the furnace is taken out, so as to ensure that the specific capacity of the tantalum core after sintering is 15500 μFV / g.

[0052] In the step S3, the forming process is voltage stage boosting forming, and the steps include forming step A, forming step B, heat treatment, supplement forming and boiling washing in sequence.

[0053] The forming solution used in the forming process is ethylene glycol phosphate, and the forming step A includes: soaking at a temperature of 89℃, soaking time: 3h of uncharged soaking and 0.5-2h of soaking under the application of a 3V voltage.

[0054] The forming step B includes: at current densities of 60V, 0.08nCV / 100mA; 90V, 0.06nCV / 100mA; and 142V, 0.04nCV / 100mA in sequence, constant voltage for 9h in each stage.

[0055] The heat treatment includes: keeping at 400℃ for 45min.

[0056] The supplement forming step includes: constant voltage for 40min at 85V; constant voltage for 40min at 95V; constant voltage for 40min at 105V; constant voltage for 40min at 115V; constant voltage for 40min at 125V; constant voltage for 40min at 135V; and constant voltage for 40min at 145V.

[0057] The boiling and washing step includes boiling and washing in deionized water at 125°C for 35 minutes, and re-boiling and washing seven times, and drying for 3.5 hours after taking out, to prepare the tantalum core with good Ta2O5 dielectric oxide film.

[0058] The step S4 includes: using sulfuric acid electrolyte to immerse and treat the tantalum core with Ta2O5 dielectric oxide film for 2 hours, using electrolyte added with copper sulfate polarization agent to assemble, and then using conventional packaging mode to tin solder packaging, and the immersion and treatment and packaging can be conventional steps.

[0059] The step S5 includes: maintaining at room temperature and 6V for 3 hours, then maintaining at room temperature and 90V for 8 hours, then maintaining at 75°C and 90V for 8 hours, then maintaining at 140°C and 70V for 4 hours, and then maintaining at 95°C and 90V for 55 hours, and the voltage increasing speed is 7V / 20min.

[0060] Example 3:

[0061] A method for preparing a capacitor with reduced tantalum capacitance attenuation, comprising the following steps:

[0062] S1: preparing tantalum powder into a tantalum block;

[0063] S2: sintering the tantalum block;

[0064] S3: forming process of the tantalum block to obtain a tantalum core with dielectric oxide film;

[0065] S4: immersing and treating the tantalum core with dielectric oxide film, and then packaging the tantalum core;

[0066] S5: completing the preparation of the capacitor after aging and aging of the packaged tantalum core.

[0067] In the step S1, 22300mg of tantalum powder with specific capacity of 15000μFV / g is accurately weighed by using an electronic analytical balance, and is formed by using a φ14.2 forming die with stearic acid as lubricant, and a certain strength of anode tantalum block is obtained after slow demolding.

[0068] In the step S2, the sintering temperature is 1630°C, and the temperature is maintained for 40 minutes after reaching the temperature, and the furnace is taken out after cooling to 30°C, to ensure that the specific capacity of the tantalum core after sintering is 14000μFV / g.

[0069] In the step S3, the forming process is voltage step voltage forming, and the steps include: forming step A, forming step B, heat treatment, supplementary forming and boiling and washing.

[0070] The forming solution used in the forming process is ethylene glycol phosphate, and the forming step A comprises: soaking at a temperature of 86°C, soaking time: 2h of uncharged soaking, 1h of soaking under the application of a 3V voltage.

[0071] The forming step B comprises: constant voltage for 6h at each stage under the current density of 30V, 0.08nCV / 100mA; 80V, 0.06nCV / 100mA; 110V, 0.04nCV / 100mA in sequence.

[0072] The heat treatment comprises: keeping at 360°C for 30min.

[0073] The complementary forming step comprises: constant voltage for 20min at 80V; constant voltage for 20min at 90V; constant voltage for 20min at 100V; constant voltage for 20min at 110V; constant voltage for 20min at 120V; constant voltage for 20min at 130V; constant voltage for 20min at 142V.

[0074] The boiling washing step comprises: boiling washing in deionized water at a temperature of 110°C for 32min, and boiling washing for six to seven times, and drying for 3.5h after taking out, to prepare a tantalum core with a good Ta2O5 dielectric oxide film.

[0075] The soaking treatment step in the step S4 comprises: soaking treatment of the tantalum core with the Ta2O5 dielectric oxide film for 1h using a sulfuric acid electrolyte, assembling using an electrolyte added with copper sulfate polarizer, and then tin soldering packaging using a conventional packaging method, and the soaking treatment and packaging can be conventional steps.

[0076] The aging step of the packaged tantalum core in the step S5 comprises in sequence: keeping at room temperature and 3V for 2h; then keeping at room temperature and 77V for 6h; then keeping at 65°C and 77V for 6h; then keeping at 125°C and 58V for 2h; then keeping at 85°C and 77V for 48h; the voltage increasing speed is 5V / 20min.

[0077] Comparative Example 1:

[0078] A CAK35 type 75V2200μF non-solid electrolyte tantalum capacitor produced by using the prior art.

[0079] CAK35 type 75V2200μF non-solid electrolyte tantalum capacitors are produced by the method of Examples 1-3, and the capacity loss of the capacitors of Comparative Example 1 after aging for 480h is shown in the following table.

[0080] Group Volume loss (%) Example 1 5.15 Example 2 3.36 Example 3 2.38 Comparative Example 1 18.08

[0081] As shown in the above table, the method of the present application can produce a non-solid electrolytic tantalum capacitor with high voltage and large capacity, and the capacitor produced by the method has greatly reduced loss of capacitance after aging.

[0082] The method of the present application is suitable for the preparation of a non-solid electrolytic tantalum electrolytic capacitor.

Claims

1. A method of making a capacitor with reduced tantalum capacitance decay, comprising: The method comprises the following steps: S1: preparing tantalum powder into tantalum block; S2: sintering the tantalum block; S3: forming process on the tantalum block to obtain tantalum core with dielectric oxide film; S4: immersing the tantalum core with dielectric oxide film, and then packaging the tantalum core; S5: aging the packaged tantalum core, and then completing the preparation of the capacitor; In the step S2, the sintering temperature is 1500-1700℃, and the temperature is kept for 30-50min, and the furnace is taken out after cooling to 30℃, so as to ensure that the specific capacitance of the tantalum core after sintering is 13500-15500μFV / g; In the step S3, the forming process is voltage segment voltage boosting forming, and the steps include forming step A, forming step B, heat treatment, supplement forming and boiling washing; The forming liquid used in the forming process is ethylene glycol phosphate, and the forming step A includes: soaking at a temperature of 86-89℃, soaking time: 1-3h without electricity, and soaking for 0.5-2h under the application of 3V voltage; The forming step B includes: under the current density of 0-60V, 0.08nCV / 100mA; 60-90V, 0.06nCV / 100mA; 90-142V, 0.04nCV / 100mA, respectively, constant voltage for 4-9h in each stage; The heat treatment includes: keeping at 300-400℃ for 20-45min; The supplement forming step includes: constant voltage for 10-40min at 75-85V; constant voltage for 10-40min at 86-95V; constant voltage for 10-40min at 96-105V; constant voltage for 10-40min at 106-115V; constant voltage for 10-40min at 116-125V; constant voltage for 10-40min at 126-135V; constant voltage for 10-40min at 136-145V.

2. The method of claim 1 wherein: the tantalum capacitor is a tantalum capacitor having a reduced capacitance decay. In the step S1, the tantalum powder with specific capacitance of 15000μFV / g is formed by using a lubricant forming die, and the anode tantalum block is obtained after slow demolding.

3. The method for preparing a capacitor with reduced tantalum capacitance decay as described in claim 1, characterized in that: The boiling washing step includes boiling washing in deionized water at a temperature of 100-125℃ for 30-35min, and the boiling washing is repeated for six to seven times, and the tantalum core with good dielectric oxide film is prepared after taking out and drying for 3-3.5h.

4. The method for preparing a capacitor with reduced tantalum capacitance decay as described in claim 1, characterized in that: In the step S4, the immersing treatment step includes: immersing the tantalum core with dielectric oxide film in sulfuric acid electrolyte for 0.5-2h, assembling the electrolyte added with a compound polarizer composed of sulfate ions and metal cations, and then tin solder packaging.

5. The method of claim 1 wherein: the tantalum capacitor is a low rate capacitor. In the step S5, the aging step of the packaged tantalum core includes: keeping at room temperature and 1-6V for 1-3h; then keeping at room temperature and 60-90V for 4-8h; then keeping at 55-75℃ and 60-90V for 4-8h; then keeping at 110-140℃ and 40-70V for 1-4h; then keeping at 75-95℃ and 60-90V for 40-55h; and the voltage boosting speed is 2-7V / 20min. ​ 6. A capacitor prepared by the method of any one of claims 1-5.