Quality detection method for tantalum capacitor dielectric film

Abstract

The invention discloses a tantalum capacitor dielectric film quality detection method. The method comprises the following steps that a formed tantalum block is connected to a fixing piece; weighing and recording the initial weight of the tantalum block; electroplating the tantalum block; cleaning the tantalum block after electroplating is completed; then drying the tantalum block; weighing and recording the weight of the electroplated tantalum block; and finally checking the tantalum block. The formed tantalum core is electroplated with tin metal, the quality of a tantalum core dielectric oxide film can be judged by calculating the weight growth rate of the tantalum block, the defect position of the oxide film is judged by observing distribution of tin on the surface of the tantalum block through a microscope, the defect position can be known conveniently, and the tantalum block preparation technology is better improved. The detection method is easy to operate, low in cost and suitable for detection of preparation of capacitors of various models.

Description

Technical Field

[0001] The invention belongs to the technical field of capacitor preparation, and in particular relates to a method for detecting the quality of a tantalum capacitor dielectric film. Background Art

[0002] In recent years, with the increasing requirements of electronic components in electronic systems and the development of capacitor manufacturing technology, the performance of chip tantalum capacitors has gradually improved.

[0003] At present, the quality of the dielectric oxide film after the formation of tantalum capacitors is usually characterized by the size of the DC leakage current, that is, the quality of the dielectric oxide film is qualitatively evaluated by testing the DC leakage current. This method is greatly affected by the test liquid, test temperature, test voltage, etc., and it is impossible to determine the defect distribution of the dielectric oxide film of the tantalum core as a whole. In addition to measuring the DC leakage current, there is no other way to accurately judge the quality of the dielectric oxide film. Therefore, it is particularly important to seek a method to judge the quality of the dielectric oxide film for the quality of the tantalum core after formation.

[0004] Theoretically, the tantalum pentoxide dielectric film is an insulator and does not conduct electricity itself, so no reaction occurs when a DC voltage is applied to the completed tantalum capacitor in the plating tank. However, due to the presence of defects in the dielectric oxide film, there is a conductive channel in the dielectric layer, so after a certain voltage is applied, the tin ions in the plating solution will gain electrons and be reduced to tin metal, which will be continuously deposited at the defect location. The reaction is as follows:

[0005] Cathode (Tantalum core): Sn 2+ +2e→Sn(main reaction)

[0006] 2H + +2e→H2↑(side reaction)

[0007] Anode (tin plate): Sn-2e → Sn 2+ (Main reaction)

[0008] 4OH - -4e→2H2O+O2↑(side reaction)

[0009] Therefore, this feature can be used to detect defects in tantalum pentoxide dielectric films. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a method for detecting the quality of a tantalum capacitor dielectric film.

[0011] The present invention is achieved through the following technical solutions.

[0012] The present invention provides a method for detecting the quality of a tantalum capacitor dielectric film, comprising the following steps:

[0013] 1) Connect the finished tantalum block to the fixing part;

[0014] 2) Weigh and record the initial weight of the tantalum block;

[0015] 3) electroplating the tantalum block;

[0016] 4) Clean the tantalum block after electroplating;

[0017] 5) Drying the cleaned tantalum block;

[0018] 6) Weigh and record the weight of the tantalum block after electroplating;

[0019] 7) Inspect the tantalum block.

[0020] Preferably, in the step 1), the formed tantalum block is welded to the fixing member by resistance welding or laser welding.

[0021] Preferably, the electroplating step in step 3) comprises: connecting the tantalum block to the negative electrode of a DC power supply, connecting the connecting plate to the positive electrode of the power supply, and then placing the tantalum block in an electrolyte for electroplating.

[0022] Preferably, the electroplating conditions include: applying a voltage of 1-5V, a current of 0.1-1A, and an electroplating time of 5-30min.

[0023] Preferably, the voltage is a DC voltage.

[0024] Preferably, the electrolyte comprises the following components: methanesulfonic acid concentrate, tin concentrate and deionized water, wherein the methanesulfonic acid is concentrated to 80-150 ml / L and the methanesulfonic acid content is 50-80%; the tin concentrate is 40-80 ml / L and the tin content is 200-400 g / L; and the balance is deionized water.

[0025] Preferably, the connecting plate is made of tin.

[0026] Preferably, in step 4), the electroplated tantalum block is sprayed with deionized water and then placed in a water washing tank with a temperature of 65°C-90°C and a water flow rate of 5L / min-10L / min for boiling and washing; the boiling and washing time is 40-90min.

[0027] Preferably, in step 6), the cleaned tantalum block is placed at a temperature of 85° C.-120° C. and dried for 10 min-30 min.

[0028] Preferably, in step 7), a stereo microscope is used to observe the distribution state of the metallic tin on the surface of the tantalum core after 10-40 times magnification.

[0029] The beneficial effects of the present invention are:

[0030] The present invention can evaluate the quality of the tantalum core dielectric oxide film by electroplating tin metal on the completed tantalum core by calculating the weight growth rate of the tantalum block, and evaluate the defective parts of the oxide film by observing the distribution of tin on the surface of the tantalum block with a microscope, so as to understand the defective positions and better improve the tantalum block preparation process. The detection method of the present application is simple to operate, low in cost, and suitable for the detection of the preparation of various types of capacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a process schematic diagram of the present invention;

[0032] Figure 2 This is a 20-fold magnification image of the capacitor of batch 1 detected in Example 3 under a stereo microscope;

[0033] Figure 3 This is a 20-fold magnification image of the capacitors of batch 2 detected in Example 3 using a stereo microscope. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0035] Embodiment 1:

[0036] like Figure 1 As shown, a method for detecting the quality of a tantalum capacitor dielectric film comprises the following steps:

[0037] 1) Connect the finished tantalum block to the fixing part;

[0038] 2) Use an electronic balance with an accuracy of 0.01g to weigh and record the initial weight of the tantalum block;

[0039] 3) electroplating the tantalum block;

[0040] 4) Clean the tantalum block after electroplating;

[0041] 5) Drying the cleaned tantalum block;

[0042] 6) Use an electronic balance with an accuracy of 0.01g to weigh and record the weight of the tantalum block after electroplating;

[0043] 7) Inspect the tantalum block.

[0044] In the step 1), the formed tantalum block is welded to the steel bar fixing member by resistance welding or laser welding.

[0045] The electroplating step in step 3) includes: connecting the tantalum block to the negative pole of a DC power supply, connecting the tin connecting plate to the positive pole of the power supply, and then placing the tantalum block in an electrolyte for electroplating.

[0046] The electroplating conditions include: applying a 1V DC voltage, a 1A current, and an electroplating time of 30 minutes.

[0047] The electrolyte comprises the following components: methanesulfonic acid concentrate, tin concentrate and deionized water, wherein the methanesulfonic acid is concentrated to 80 ml / L, with a methanesulfonic acid content of 50%; the tin concentrate is 40 ml / L, with a tin content of 200 g / L; deionized water is then added to fill the container to 1 L, and electroplating additives are used according to actual conditions.

[0048] In the step 4), the electroplated tantalum block is sprayed with deionized water and then placed in a water washing tank with a temperature of 65° C. and a water flow rate of 5 L / min for boiling and washing; the boiling and washing time is 40 minutes.

[0049] In step 6), the cleaned tantalum block is placed in an oven at 85° C. and dried for 30 minutes.

[0050] In the step 7), a stereo microscope is used to magnify the tantalum core by 20 times to observe the distribution of the metal tin on the surface of the tantalum core.

[0051] Embodiment 2:

[0052] like Figure 1 As shown, a method for detecting the quality of a tantalum capacitor dielectric film comprises the following steps:

[0053] 1) Connect the finished tantalum block to the fixing part;

[0054] 2) Use an electronic balance with an accuracy of 0.01g to weigh and record the initial weight of the tantalum block;

[0055] 3) electroplating the tantalum block;

[0056] 4) Clean the tantalum block after electroplating;

[0057] 5) Drying the cleaned tantalum block;

[0058] 6) Use an electronic balance with an accuracy of 0.01g to weigh and record the weight of the tantalum block after electroplating;

[0059] 7) Inspect the tantalum block.

[0060] In the step 1), the formed tantalum block is welded to the steel bar fixing member by resistance welding or laser welding.

[0061] The electroplating step in step 3) includes: connecting the tantalum block to the negative pole of a DC power supply, connecting the tin connecting plate to the positive pole of the power supply, and then placing the tantalum block in an electrolyte for electroplating.

[0062] The electroplating conditions include: applying a 3V DC voltage, a 0.5A current, and an electroplating time of 20 minutes.

[0063] The electrolyte comprises the following components: methanesulfonic acid concentrate, tin concentrate and deionized water, wherein the methanesulfonic acid is concentrated to 150 ml / L, with a methanesulfonic acid content of 80%; the tin concentrate is 80 ml / L, with a tin content of 400 g / L; deionized water is then added to fill the container to 1 L, and electroplating additives are used according to actual conditions.

[0064] In the step 4), the electroplated tantalum block is sprayed with deionized water and then placed in a water washing tank with a temperature of 90° C. and a water flow rate of 10 L / min for boiling and washing; the boiling and washing time is 90 minutes.

[0065] In step 6), the cleaned tantalum block is placed in an oven at 120° C. and dried for 10 minutes.

[0066] In the step 7), a stereo microscope is used to magnify the tantalum core by 20 times to observe the distribution of the metal tin on the surface of the tantalum core.

[0067] Embodiment 3:

[0068] like Figure 1 As shown, a method for detecting the quality of a tantalum capacitor dielectric film comprises the following steps:

[0069] 1) Connect the finished tantalum block to the fixing part;

[0070] 2) Use an electronic balance with an accuracy of 0.01g to weigh and record the initial weight of the tantalum block;

[0071] 3) electroplating the tantalum block;

[0072] 4) Clean the tantalum block after electroplating;

[0073] 5) Drying the cleaned tantalum block;

[0074] 6) Use an electronic balance with an accuracy of 0.01g to weigh and record the weight of the tantalum block after electroplating;

[0075] 7) Inspect the tantalum block.

[0076] In the step 1), the formed tantalum block is welded to the steel bar fixing member by resistance welding or laser welding.

[0077] The electroplating step in step 3) includes: connecting the tantalum block to the negative pole of a DC power supply, connecting the tin connecting plate to the positive pole of the power supply, and then placing the tantalum block in an electrolyte for electroplating.

[0078] The electroplating conditions include: applying a DC voltage of 5V, a current of 0.1A, and an electroplating time of 10 minutes.

[0079] The electrolyte comprises the following components: methanesulfonic acid concentrate, tin concentrate and deionized water, wherein the methanesulfonic acid is concentrated to 120 ml / L, with a methanesulfonic acid content of 70%; the tin concentrate is 50 ml / L, with a tin content of 300 g / L; deionized water is then added to fill the container to 1 L, and electroplating additives are used according to actual conditions.

[0080] In the step 4), the electroplated tantalum block is sprayed with deionized water and then placed in a water washing tank with a temperature of 75° C. and a water flow rate of 7 L / min for boiling and washing; the boiling and washing time is 75 minutes.

[0081] In step 6), the cleaned tantalum block is placed in an oven at a temperature of 100° C. and dried for 20 minutes.

[0082] In the step 7), a stereo microscope is used to magnify the tantalum core by 20 times to observe the distribution of the metal tin on the surface of the tantalum core.

[0083] Two different batches of CAK45-F-63V 10 μF capacitors were selected and tested using the method of Example 3 after the leakage current was tested. The results are shown in the following table.

[0084] Table 1 Comparison of capacitor leakage current and weight before and after electroplating

[0085]

[0086] By comparing the weight growth rates of the two batches of samples after electroplating, it can be seen that the dielectric oxide film of sample 1 has more defects. This method can quickly understand the defect situation. Figure 2 This is a 20x magnification image of batch 1 under a stereo microscope. Figure 3 This is a 20x magnified image of batch 2 taken with a stereo microscope. It can also be found visually that there are many defective areas on the surface of the tantalum core, and the defective areas are mainly concentrated at the bottom of the tantalum block. Understanding the defect locations can better improve the tantalum block preparation process.

Claims

1. A method for detecting the quality of a tantalum capacitor dielectric film, characterized in that: The following steps are involved: 1) Connect the finished tantalum block to the fixing part; 2) Weigh and record the initial weight of the tantalum block; 3) electroplating the tantalum block; 4) Clean the tantalum block after electroplating; 5) Drying the cleaned tantalum block; 6) Weigh and record the weight of the tantalum block after electroplating; 7) Inspect the tantalum block.

2. A method for detecting the quality of a tantalum capacitor dielectric film according to claim 1, characterized in that: In the step 1), the formed tantalum block is welded to the fixing member by resistance welding or laser welding.

3. A method for detecting the quality of a tantalum capacitor dielectric film according to claim 1, characterized in that: The electroplating step in step 3) includes: connecting the tantalum block to the negative pole of a DC power supply, connecting the connecting plate to the positive pole of the power supply, and then placing the tantalum block in an electrolyte for electroplating.

4. A method for detecting the quality of a tantalum capacitor dielectric film as claimed in claim 3, characterized in that: The electroplating conditions include: applying a voltage of 1-5V, a current of 0.1-1A, and an electroplating time of 5-30min.

5. A method for detecting the quality of a tantalum capacitor dielectric film as claimed in claim 4, characterized in that: The voltage is a direct current voltage.

6. A method for detecting the quality of a tantalum capacitor dielectric film as claimed in claim 3, characterized in that: The electrolyte comprises the following components: methanesulfonic acid concentrate, tin concentrate and deionized water, wherein the methanesulfonic acid is concentrated to 80-150 ml / L and the methanesulfonic acid content is 50-80%; the tin concentrate is 40-80 ml / L and the tin content is 200-400 g / L; and the balance is deionized water.

7. A method for detecting the quality of a tantalum capacitor dielectric film as claimed in claim 3, characterized in that: The connecting plate is made of tin.

8. A method for detecting the quality of a tantalum capacitor dielectric film according to claim 1, characterized in that: In the step 4), the electroplated tantalum block is sprayed with deionized water and then placed in a water washing tank with a temperature of 65°C-90°C and a water flow rate of 5L / min-10L / min for boiling and washing; the boiling and washing time is 40-90min.

9. A method for detecting the quality of a tantalum capacitor dielectric film according to claim 1, characterized in that: In the step 6), the cleaned tantalum block is placed at a temperature of 85° C. to 120° C. and dried for 10 min to 30 min.

10. A method for detecting the quality of a tantalum capacitor dielectric film according to claim 1, characterized in that: In the step 7), a stereo microscope is used to magnify the tantalum core by 10-40 times to observe the distribution of the metal tin on the surface of the tantalum core.

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