Polymerization method for improving capacity extraction rate of conducting polymer chip tantalum capacitor

Abstract

The invention belongs to the technical field of tantalum capacitor manufacturing, and particularly relates to a polymerization method for improving the capacity extraction rate of a conductive polymer chip tantalum capacitor, which specifically comprises the following steps of: pretreating a formed tantalum core by using a surfactant, immersing the tantalum core into a polymerization solution in a vacuum environment, quickly taking out after dipping, transferring into polymerization equipment for chemical polymerization reaction, repeating the vacuum dipping and polymerization reaction processes for multiple times, and then sequentially drying and washing with alcohol to obtain the product. The polymerization solution comprises the following components in percentage by weight: 30wt%-80wt% of a polymeric material and 20wt%-70wt% of a solvent A. By using the method disclosed by the invention, a conductive polymer containing polythiophene and derivatives thereof can be formed on the surface of the tantalum core; according to the method, the capacity extraction rate of the tantalum capacitor can be effectively improved by more than 5%, the problem of large high-temperature capacitance variation of the conductive polymer chip type tantalum capacitor is greatly improved, and meanwhile, the polymerization method can effectively improve the production qualification rate of products and reduce the production cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of tantalum capacitor manufacturing, and in particular relates to a polymerization method for improving the capacity extraction rate of conductive polymer chip tantalum capacitors. Background Art

[0002] Low-voltage conductive polymer chip tantalum capacitors (4V<UR≤35V) are high-performance electronic components with the characteristics of low equivalent series resistance (ESR), high capacitance, miniaturization, high reliability and good temperature stability. They are produced using a chemical polymerization process. The polymerization method first immerses the formed capacitor tantalum core in a mixed solution of monomer and oxidant under atmospheric conditions for a certain period of time, and then places the tantalum core immersed in the polymerization solution in a polymerization device. The polymerization reaction is carried out at a specific temperature and humidity to produce a conductive polymer. After repeating the above process many times, a conductive polymer of a certain thickness can be formed on the surface of the tantalum core dielectric oxide film as the cathode layer of the capacitor.

[0003] The reaction rate of monomers and oxidants in the existing chemical in-situ polymerization process is relatively fast, resulting in a low capacity extraction rate for medium and low voltage conductive polymer chip tantalum capacitors (4V<UR≤35V) produced using the existing chemical in-situ polymerization process. This causes a large change in the capacitance of the capacitor at high temperature, affecting the application performance of the product. In addition, the low capacity extraction rate of the capacitor also seriously affects the production qualification rate of the product, resulting in high production costs. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention proposes a polymerization method for improving the capacity extraction rate of conductive polymer chip tantalum capacitors.

[0005] This is achieved specifically through the following technical solutions:

[0006] A polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor comprises the following steps: pre-treating a formed tantalum core with a surfactant for 3 to 5 minutes, immersing the tantalum core in a polymerization solution under a vacuum environment, quickly removing the core after the immersion is completed and transferring the core to a polymerization device for a chemical polymerization reaction, repeating the vacuum immersion and chemical polymerization reaction operations 4 to 7 times, and then drying and washing with alcohol to obtain the capacitor; the polymerization solution comprises, by weight percentage, 30 to 80 percent by weight of a polymer material and 20 to 70 percent by weight of an organic solvent.

[0007] The surfactant is a silane coupling agent containing both glycidoxy and methoxy groups, such as 3-(2,3-glycidoxy)propyltrimethoxysilane.

[0008] The mass concentration of the surfactant is 1 wt% to 10 wt%.

[0009] The polymer material is composed of monomer material: oxidant material in a mass ratio of 1:4 to 1:7.

[0010] The monomer is thiophene or a derivative thereof.

[0011] Furthermore, the thiophene derivative is at least one of 3,4-ethylenedioxythiophene, 3,4-alkylthiophene, and 3,4-alkoxythiophene.

[0012] The oxidant material is at least one of iron p-toluenesulfonate, long-chain alkylbenzenesulfonate iron, alkylnaphthalenesulfonate iron, dialkylnaphthalenesulfonate iron, and dinonylnaphthalene disulfonate iron.

[0013] The mass concentration of the oxidant material is 10.5 wt% to 55 wt%.

[0014] The organic solvent is a mixed solution of one or more organic substances selected from methanol, ethanol, isopropanol, n-butanol and tetrahydrofuran and deionized water, and the mass ratio of the organic substance to the deionized water is 4:3 to 2:1.

[0015] The process conditions of the vacuum impregnation are: vacuum degree of 35KPa to 50KPa, and time of 3min to 5min.

[0016] The process conditions of the chemical polymerization reaction are: temperature of 25° C. to 35° C., humidity of 65% RH to 75% RH, and time of 40 min to 60 min.

[0017] The alcohol washing solution is one or more of methanol, ethanol, and n-butanol, and the alcohol washing time is 60 min to 120 min.

[0018] The rated voltage of the conductive polymer chip tantalum capacitor is 4V to 35V.

[0019] Beneficial effects:

[0020] The method of the present invention can form a conductive polymer containing polythiophene and its derivatives on the surface of the tantalum core; the method of the present invention can effectively increase the capacity extraction rate of the tantalum capacitor by more than 5%, greatly improving the problem of large high-temperature capacitance variation of the conductive polymer chip tantalum capacitor. At the same time, the polymerization method can effectively improve the product production qualification rate and reduce production costs.

[0021] Prior to polymerization, the present invention utilizes a surfactant to treat the tantalum core surface, effectively improving the polymer's adhesion. The polymerization solution contains deionized water, which dissolves and dilutes the polymeric material and reduces the polymerization reaction rate. Following polymerization, the present invention utilizes an alcohol wash to effectively remove unreacted polymer solution and residual metal impurity ions from the tantalum core after the chemical polymerization reaction, effectively improving the conductivity of the conductive polymer layer. This also reduces damage to the dielectric oxide film caused by the migration and diffusion of metal impurities at high temperatures, thereby reducing capacitor leakage current. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments. Any improvement or replacement based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0023] Example 1

[0024] A polymerization method for increasing the capacity extraction rate of conductive polymer chip tantalum capacitors (rated voltage 4V to 35V):

[0025] (1) Solution preparation:

[0026] The polymerization solution is formed by mixing 30 wt% of a polymer material and 70 wt% of an organic solvent, wherein the organic solvent is a mixture of anhydrous ethanol and deionized water in a mass ratio of 3:2; the polymer material is mixed in a mass ratio of monomer material to oxidant material of 1:4; the monomer material is thiophene; and the oxidant material is a mixture of iron p-toluenesulfonate and ethanol, with a mass concentration of 10 wt%;

[0027] (2) Pretreatment: Immerse the formed tantalum core in 1 wt% 3-(2,3-epoxypropoxy)propyltrimethoxysilane under a vacuum of 35 kPa for 3 min;

[0028] (3) Vacuum impregnation: The tantalum core treated in step (2) was immersed in the polymerization solution under a vacuum condition of 35 kPa for 5 minutes. After the impregnation was completed, it was quickly taken out and transferred to the polymerization equipment for chemical polymerization reaction for 50 minutes. The polymerization reaction temperature and humidity conditions were 25°C and 75% RH. The above process was repeated 5 times;

[0029] (4) Drying and alcohol washing: The tantalum core obtained in step (3) is taken out, dried, and then washed with methanol for 60 minutes to obtain a capacitor tantalum core coated with a conductive polymer.

[0030] The conductive polymer in the tantalum capacitor manufactured by the method of this embodiment is polythiophene. After testing, its capacity extraction rate is 78% and its ERS value is 22mΩ to 28mΩ.

[0031] Example 2

[0032] A polymerization method for increasing the capacity extraction rate of conductive polymer chip tantalum capacitors (rated voltage 4V to 35V):

[0033] (1) Solution preparation:

[0034] The polymerization solution is formed by mixing 80 wt% of a polymer material and 20 wt% of an organic solvent, wherein the organic solvent is a mixture of ethanol, n-butanol, and deionized water in a mass ratio of 4:3; the polymer material is mixed in a mass ratio of monomer material to oxidant material of 1:7; the monomer material is thiophene; and the oxidant material is a mixture of alkylnaphthalene iron sulfonate and acetonitrile, with a mass concentration of 30 wt%;

[0035] (2) Pretreatment: Immerse the formed tantalum core in 5 wt% 3-(2,3-epoxypropoxy)propyltrimethoxysilane under a vacuum of 45 kPa for 4 minutes;

[0036] (3) Vacuum impregnation: The tantalum core treated in step (2) was immersed in the polymerization solution under a vacuum condition of 45 kPa for 4 minutes. After the impregnation was completed, it was quickly taken out and transferred to the polymerization equipment for polymerization reaction for 60 minutes. The polymerization reaction temperature and humidity conditions were 25°C and 75% RH. The above process was repeated 7 times;

[0037] (4) Drying and alcohol washing: The tantalum core obtained in step (2) is taken out, dried, and then washed with methanol for 90 minutes to obtain a capacitor tantalum core coated with a conductive polymer.

[0038] The conductive polymer in the tantalum capacitor manufactured by the method of this embodiment is polythiophene. After testing, its capacity extraction rate is 80% and the ERS value is 22mΩ-25mΩ.

[0039] Example 3

[0040] A polymerization method for increasing the capacity extraction rate of conductive polymer chip tantalum capacitors (rated voltage 4V to 35V):

[0041] (1) Solution preparation:

[0042] The polymerization solution is formed by mixing 50 wt% of a polymer material and 50 wt% of an organic solvent, wherein the solvent is a mixture of tetrahydrofuran and deionized water in a mass ratio of 3:2; the polymer material is mixed in a mass ratio of monomer material to oxidant material of 1:5; the monomer material is thiophene; and the oxidant material is a mixture of iron dinonylnaphthalene disulfonate and acetone, with a mass concentration of 50 wt%;

[0043] (2) Pretreatment: Under a vacuum condition of 38 kPa, the formed tantalum core was immersed in 3-(2,3-epoxypropoxy)propyltrimethoxysilane with a mass concentration of 10 wt% for 5 minutes;

[0044] (3) Vacuum impregnation: The tantalum core treated in step (2) was immersed in the polymerization solution under a vacuum condition of 38 kPa for 3 minutes. After the impregnation was completed, it was quickly taken out and transferred to the polymerization equipment for polymerization reaction for 45 minutes. The polymerization reaction temperature and humidity conditions were 25°C and 75% RH. The above process was repeated 4 times;

[0045] (4) Drying and alcohol washing: The tantalum core obtained in step (2) is taken out, dried, and then washed with 80 wt% n-butanol solution for 120 min to obtain a capacitor tantalum core coated with a conductive polymer.

[0046] The conductive polymer in the tantalum capacitor manufactured by the method of this embodiment is polythiophene. After testing, its capacity extraction rate is 78%, and its ERS value is 21mΩ to 24mΩ.

[0047] Comparative Example 1

[0048] Based on Example 1, the difference from Example 1 is that there is no deionized water in the polymerization solution, the capacity extraction rate of the prepared tantalum capacitor is 71%, and the ERS value is 21mΩ to 24mΩ.

[0049] Comparative Example 2

[0050] On the basis of Example 2, the difference from Example 2 is that the vacuum impregnation is changed to atmospheric impregnation, the capacity extraction rate of the prepared tantalum capacitor is 75%, and the ERS value is 20mΩ to 24mΩ.

[0051] Comparative Example 3

[0052] Based on Example 3, the difference from Example 3 is that the vacuum impregnation is changed to atmospheric impregnation, there is no deionized water in the polymerization solution, the capacity extraction rate of the prepared tantalum capacitor is 70%, and the ERS value is 20mΩ~23mΩ.

Claims

1. A polymerization method for increasing the capacitance extraction rate of a conductive polymer chip tantalum capacitor, characterized in that: After the formed tantalum core is pretreated with a surfactant, the tantalum core is immersed in a polymerization solution under a vacuum environment for impregnation. After the impregnation is completed, the tantalum core is quickly taken out and transferred to a polymerization device for chemical polymerization reaction. The above vacuum impregnation and chemical polymerization reaction operations are repeated multiple times, and finally the core is dried and washed with alcohol to obtain the obtained product. The polymerization solution is composed of 30wt% to 80wt% of polymer material and 20wt% to 70wt% of organic solvent in weight percentage. The organic solvent is a mixed solution of one or more organic substances selected from methanol, ethanol, isopropanol, n-butanol and tetrahydrofuran and deionized water, and the mass ratio of the organic substance to deionized water is 4:3 to 2:

1.

2. The polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 1, characterized in that: The surfactant is a silane coupling agent containing both glycidoxy and methoxy groups; the mass concentration of the surfactant is 1 wt% to 10 wt%.

3. The polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 1, characterized in that: The polymer material is composed of monomer material: oxidant material in a mass ratio of 1:4 to 1:

7.

4. The polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 2, characterized in that: The monomer is thiophene or a derivative thereof.

5. The polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 2, characterized in that: The oxidant material is at least one of iron p-toluenesulfonate, long-chain alkylbenzenesulfonate iron, alkylnaphthalenesulfonate iron, dialkylnaphthalenesulfonate iron, and dinonylnaphthalene disulfonate iron; and the mass concentration of the oxidant material is 10.5wt% to 55wt%.

6. The polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 1, characterized in that: The process conditions of the vacuum impregnation are: vacuum degree of 35KPa to 50KPa, and time of 3min to 5min.

7. The polymerization method for increasing the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 1, characterized in that: The process conditions of the chemical polymerization reaction are: temperature of 25° C. to 35° C., humidity of 65% RH to 75% RH, and time of 40 min to 60 min.

8. The polymerization method for increasing the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 1, characterized in that: The alcohol washing solution is one or more of methanol, ethanol, and n-butanol.

9. The polymerization method for improving the capacitance extraction rate of a conductive polymer chip tantalum capacitor according to claim 1, characterized in that: The rated voltage of the conductive polymer chip tantalum capacitor is 4V to 35V.