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CN-122025424-A - Preparation method of solid tantalum capacitor

CN122025424ACN 122025424 ACN122025424 ACN 122025424ACN-122025424-A

Abstract

The solid tantalum capacitor consists of a tantalum block, a medium oxide layer with gradient thickness, a cathode layer, a transition layer, a silver layer and a plastic sealing layer, wherein the thickness of the medium oxide layer gradually decreases along the gradient nonlinearity from the outer surface of the tantalum block to the body center of the tantalum block; the preparation method of the solid tantalum capacitor comprises the following steps of pressing and sintering, energizing, heat treatment, complementary formation, coating, graphite silver paste, plastic packaging and multiple ageing, wherein the ageing process is carried out in the environment of 60-90% of relative humidity, 60-125 ℃ of ageing temperature and 0.6-1.5 times of rated voltage, the secondary energizing and multiple humidifying ageing process are adopted, so that the thickness of a dielectric oxide layer of the solid tantalum capacitor is gradually reduced from outside to inside, the capacity contribution degree is gradually increased from outside to inside, the short plate effect of an external dielectric oxide layer is supplemented, the integral voltage endurance capacity of the tantalum capacitor is improved, and the capacity of the tantalum capacitor is not sacrificed.

Inventors

  • WU DEGUI
  • GUO YAO
  • LI MINGPEI
  • XU KUNFENG
  • CHEN YUKUN

Assignees

  • 福建火炬电子科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260403

Claims (8)

  1. 1. The preparation method of the solid tantalum capacitor comprises a tantalum block, a medium oxide layer with gradient thickness, a cathode layer, a transition layer, a silver layer and a plastic sealing layer, and is characterized in that the thickness of the medium oxide layer is in gradient nonlinear decrease along the outer surface of the tantalum block to the body center of the tantalum block; the preparation method of the solid tantalum capacitor comprises the following steps of pressing and sintering, energizing, heat treatment, complementary forming, coating, graphite silver paste, plastic packaging and multiple ageing; The energizing process comprises the steps of firstly, pressing a sintered tantalum block in a first solution to form a voltage U 1 at the current density of I 1 , then, keeping constant voltage under the voltage U 1 until the current density is reduced to 0.2-0.5mA/g, cleaning, drying, transferring to a second solution, raising the voltage to form a voltage U 2 , and then keeping constant voltage under the voltage U 2 until the thickness of the surface layer of the tantalum block reaches a target value; the aging process is carried out in the environment of 60-90% relative humidity, 60-125 ℃ aging temperature and 0.6-1.5 times rated voltage.
  2. 2. The method for manufacturing a solid tantalum capacitor according to claim 1, wherein the aging step is performed for a plurality of times by aging the capacitor once at a rated voltage of 0.8 to 1.1 times and a relative humidity of 60 to 90% for 10 to 15 hours, then aging the capacitor twice at a rated voltage of 1.1 to 1.5 times and a relative humidity of 60 to 90% for 5 to 10 hours, and then aging the capacitor three times at a rated voltage of 0.8 to 1.1 times and a relative humidity of 60 to 90% for 3 to 6 hours.
  3. 3. The method for manufacturing a solid tantalum capacitor according to claim 1, wherein in said energizing step, a current density I 1 is 20-120mA/g, a step-up rate of a second solution to a formation voltage U 2 is 10-30V/min, and said formation voltage U 2 is 1.5-5 times a formation voltage U 1 .
  4. 4. The method of manufacturing a solid tantalum capacitor according to claim 1, wherein said first solution is used at a temperature of 50-125℃and said second solution is used at a temperature of 20-50 ℃.
  5. 5. The method of manufacturing a solid tantalum capacitor according to claim 1, wherein said first solution is 0.02-0.3wt% phosphoric acid or 0.05-1wt% nitric acid solution.
  6. 6. The method of manufacturing a solid tantalum capacitor according to claim 1 wherein said second solution comprises 0.5-3wt% of a monobasic weak acid salt solution, wherein said monobasic weak acid salt cation is selected from the group consisting of ammonium, lithium, sodium, potassium and calcium, and wherein said monobasic weak acid salt anion is selected from the group consisting of acetate, propionate, glycolate, tetrahydroxyborate, tetraborate, pentaborate, hypophosphite, benzoate, preferably acetate, tetraborate and pentaborate.
  7. 7. The method of manufacturing a solid tantalum capacitor according to claim 1 wherein said cathode layer is comprised of a conductive polymer selected from one or more of polythiophene, polypyrrole or polyaniline or manganese dioxide.
  8. 8. The method of manufacturing a solid tantalum capacitor according to claim 1 wherein said transition layer is comprised of one or more of graphite, carbon black, carbon fiber or graphene.

Description

Preparation method of solid tantalum capacitor Technical Field The invention belongs to the field of tantalum capacitor preparation, and particularly relates to a preparation method of a solid tantalum capacitor. Background The tantalum capacitor is widely applied to various electronic devices such as aerospace, electronic communication, automobile electronics and the like by virtue of the advantages of small volume, high capacity density and excellent reliability, and is a core passive component in a modern electronic system. The core structure mainly comprises a tantalum block, a dielectric oxide layer, a cathode layer and a transition layer, wherein the dielectric oxide layer is used as a core layer for realizing the functions of energy storage and direct current isolation, and the structural stability of the dielectric oxide layer directly determines key indexes such as the service life, the voltage resistance and the like of the capacitor, and is a core factor for influencing the quality and the application reliability of a product. In the manufacturing, application and reliability test process of the solid tantalum capacitor, high temperature, surge voltage, mechanical vibration and the like are quite common, a dielectric oxide layer on the outer surface of the tantalum block is directly contacted with a cathode layer and is easy to be repeatedly stimulated by thermal stress and mechanical stress, so that failure phenomena such as cracking and breakdown occur on the dielectric oxide layer, in contrast, the dielectric oxide layer on the body center part of the tantalum block has better stability, and therefore the stability requirement of the dielectric oxide layer is higher when the tantalum block is close to the outside. In general, in order to improve the stability of the dielectric oxide layer, the thickness of the dielectric oxide layer needs to be increased, however, the thickness of the dielectric oxide layer has a negative correlation with the capacity of the capacitor, and the capacitor capacity is greatly lost due to the thickening of the dielectric oxide layer. Aiming at the technical bottlenecks, a technical scheme capable of meeting the requirements of the stability and the capacity of the dielectric layer of the solid tantalum capacitor is needed. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a preparation method of a solid tantalum capacitor. The invention adopts the following technical scheme: The solid tantalum capacitor consists of a tantalum block, a medium oxide layer with gradient thickness, a cathode layer, a transition layer, a silver layer and a plastic sealing layer, wherein the thickness of the medium oxide layer is in gradient nonlinear decrease along the outer surface of the tantalum block to the body center of the tantalum block; the preparation method of the solid tantalum capacitor comprises the following steps of pressing and sintering, energizing, heat treatment, complementary forming, coating, graphite silver paste, plastic packaging and multiple ageing; The energizing process comprises the steps of firstly, pressing a sintered tantalum block in a first solution to form a voltage U 1 at the current density of I 1, then, keeping constant voltage under the voltage U 1 until the current density is reduced to 0.2-0.5mA/g, cleaning, drying, transferring to a second solution, raising the voltage to form a voltage U 2, and then keeping constant voltage under the voltage U 2 until the thickness of the surface layer of the tantalum block reaches a target value; the aging process is carried out in the environment of 60-90% relative humidity, 60-125 ℃ aging temperature and 0.6-1.5 times rated voltage. Further, the operation of the multiple ageing procedures is specifically that the plastic-packaged capacitor is firstly aged for 10-15 hours under the conditions that the relative humidity is 60-90% and the rated voltage is 0.8-1.1 times, then is secondarily aged for 5-10 hours under the conditions that the relative humidity is 60-90% and the rated voltage is 1.1-1.5 times, and then is subjected to three-time ageing for 3-6 hours under the conditions that the relative humidity is 60-90% and the rated voltage is 0.8-1.1 times, so that the solid tantalum capacitor is obtained. Further, in the energizing process, the current density I 1 is 20-120mA/g, the boosting rate of the second solution to the forming voltage U 2 is 10-30V/min, and the forming voltage U 2 is 1.5-5 times of the forming voltage U 1. Further, the use temperature of the first solution is 50-125 ℃, and the use temperature of the second solution is 20-50 ℃. Further, the first solution is 0.02-0.3wt% phosphoric acid or 0.05-1wt% nitric acid solution. Further, the second solution comprises 0.5-3wt% of a monobasic weak acid salt solution, wherein the cation of the monobasic weak acid salt is selected from ammonium ion, lithium ion, sodium ion, potassium ion and calcium ion