Method for testing the corrosion of a potting compound on a metallized film

Abstract

This invention discloses a method for testing the corrosivity of potting compounds to metallized films, comprising: a potting compound corrosion step, wherein a certain mass of potting compound sample is taken and coated onto the metallization layer of the metallized film; a vacuum settling step, wherein the metallized film coated with the potting compound sample is placed in a vacuum environment and settling for 240 hours; during the settling process, a voltage is applied to the metallized film; and a testing step, wherein the sheet resistance of the metallized film is tested in a heated environment. This method for testing the corrosivity of potting compounds to metallized films can effectively shorten the testing time and improve the testing accuracy.

Description

Technical Field

[0001] This invention relates to the field of metallized thin film corrosion testing technology, and more particularly to a method for testing the corrosion of metallized thin films by potting compound. Background Technology

[0002] Currently, directly injecting polyurethane potting compound into the interior of capacitors containing metallized film elements for evaluation is time-consuming, as corrosive substances in the polyurethane potting compound typically require a long migration path to reach the surface of the metallized film. The conventional approach involves injecting the polyurethane potting compound into the casing containing the metallized film element for curing, followed by at least 1000 hours of electrical aging testing, and, if necessary, a storage test lasting at least one year to determine the corrosiveness of the polyurethane potting compound to the metallized film element. This process is quite time-consuming.

[0003] Because the interlayer gaps of metallized thin film components are small, and the viscosity of polyurethane potting compound before curing is relatively high and the reaction rate is relatively fast, it is insufficient to penetrate through the gold plating layer on the end face. Therefore, the polyurethane potting compound does not directly contact the coating of the metallized film. Corrosive substances that may be contained in it can only reach the surface of the metallized film through long-term diffusion, so the evaluation cycle is long.

[0004] Secondly, it is difficult to rule out the influence of moisture, and it is impossible to distinguish whether the corrosion is caused by corrosive substances inside the polyurethane or by moisture, and whether the polyurethane potting compound is corroded under the influence of moisture. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for testing the corrosivity of potting compounds to metallized films, which can effectively shorten the testing time and improve the testing accuracy.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for testing the corrosivity of potting compound to metallized films, comprising,

[0008] In the potting compound etching step, a certain mass of potting compound sample is taken and coated onto the metallization layer of the metallization film.

[0009] The vacuum settling step involves placing the metallized film coated with the potting compound sample in a vacuum environment and settling it for 120-240 hours; during the settling process, a voltage is applied to the metallized film.

[0010] The test procedure involves testing the sheet resistance of the metallized thin film in a heated environment.

[0011] Furthermore, in the vacuum settling step, the metallized thin film during the settling process is heated.

[0012] Furthermore, the heating temperature is 120°C. o C.

[0013] Furthermore, in the test step, the temperature of the heating environment is 85±2℃ or 105±2℃.

[0014] Furthermore, in the vacuum settling step, the voltage applied to the metallized thin film is 250VDC / μm.

[0015] Furthermore, in the potting compound etching step, the potting compound sample is coated onto the metallization layer of the metallization film and then pressurized by a pressure block.

[0016] Furthermore, the pressure applied to the metallization layer of the metallization film by the pressing is greater than or equal to 50 kPa.

[0017] Furthermore, in the vacuum settling step, the absolute vacuum level of the vacuum environment is less than or equal to 1 kPa.

[0018] Furthermore, the potting compound is one of polyurethane potting compound, epoxy resin potting compound, and silicone potting compound.

[0019] Furthermore, the metallized film is a metallized film with edges left on both sides, and a voltage of 1000VDC / mm is applied to the edges of the metallized film during the vacuum settling step.

[0020] Compared with the prior art, the advantages of the present invention are as follows: During testing, the polyurethane potting compound can be directly coated onto the metal coating of the metallized film, allowing for direct contact. Corrosive substances in the polyurethane potting compound only need to migrate to enter the metal coating, requiring a relatively short settling time. In addition, settling under vacuum reduces moisture and the corrosive effects of moisture on the polyurethane potting compound. Furthermore, the testing is conducted in a heated environment, further reducing moisture interference.

[0021] By applying voltage during the static setting process, the effect of electrolysis on corrosion during use can be simulated. Detailed Implementation

[0022] The present invention will now be further described in conjunction with specific embodiments:

[0023] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0025] Example 1,

[0026] A method for testing the corrosivity of potting compound to metallized films, comprising,

[0027] In the potting compound etching step, a certain mass of potting compound sample is taken and coated onto the metallization layer of the metallization film.

[0028] In the vacuum settling step, the metallized film coated with the potting compound sample is placed in a vacuum environment and settling for 240 hours; during the settling process, a voltage is applied to the metallized film.

[0029] The test procedure involves testing the sheet resistance of the metallized thin film in a heated environment.

[0030] In the above test steps, since the potting compound sample is directly coated on the metal coating of the metallized film and is in direct contact, the corrosive substances in the polyurethane potting compound only need to migrate to enter the metal coating, and the required standing time is relatively short.

[0031] Furthermore, since the settling process takes place in a vacuum environment, which has low moisture content and is isolated from air, the settling under vacuum reduces the corrosive effects of air moisture on the polyurethane potting compound. The voltage applied during the settling process can simulate the corrosive effects of electrolysis during use.

[0032] The tests were also conducted in a heated environment to further reduce moisture interference, resulting in more accurate test results.

[0033] Thus, under vacuum and heating conditions, the cured polyurethane potting compound is pressed onto a metallized film that is subjected to alternating current or direct current. After a period of time, the corrosiveness of the polyurethane potting compound to the metallized film is evaluated by testing the sheet resistance of the metallized film and observing the corrosion area of ​​the metal coating on the surface of the metallized film.

[0034] If the increase in sheet resistance of the metallized film before and after the test does not exceed 20%, and the corrosion or loss area of ​​the coating does not exceed 5%, then the polyurethane potting compound is considered non-corrosive to the metallized film. In other words, before testing the metallized film, the sheet resistance of the metallized coating can be tested and recorded. Then, the sheet resistance of the metallized film after the potting compound sample is coated with the coating can be tested, and the two test values ​​can be compared.

[0035] Meanwhile, before testing the metallized thin film, the area of ​​the metallized coating of the metallized thin film can be tested and recorded. Then, the corrosion area of ​​the metallized thin film after the potting compound sample is coated can be tested and recorded. The two test values ​​can be compared. In this way, the corrosion can be evaluated by using two parameters: sheet resistance and corrosion area.

[0036] It should be noted that the aforementioned vacuum environment can be achieved by using existing vacuum pumping equipment. During testing, existing heating equipment can also be used to heat the environment until the ambient temperature reaches the test temperature.

[0037] Of course, the above-mentioned potting compound samples should have a flat surface that is not contaminated by pollutants, so that they will not interfere with the corrosion test when in contact with the metal coating of the metallized film.

[0038] Specifically, in this embodiment, the ambient temperature of the test can be raised to 120°C using a heating device. o C. In this way, the temperature will not be too high to affect the performance of the metallized film itself, and the moisture in the environment can be fully evaporated, effectively removing moisture interference.

[0039] Furthermore, the metallized film can be heated during the vacuum settling step. This heating can reduce moisture interference during the settling process and can also simulate the corrosive effect of the potting compound on the metallized film caused by the working temperature of the capacitor, making the test results more stable.

[0040] Specifically, during the testing process, the temperature of the heating environment is 85±2℃ or 105±2℃. The temperature is not too high, which would affect the performance of the metallized film itself, and it also allows the moisture in the environment to evaporate fully, effectively removing moisture interference.

[0041] Furthermore, during the vacuum settling step, the voltage applied to the metallized film is 250VDC / μm. For example, if the thickness of the metallized film is 4.8μm, the applied DC voltage should be 250VDC / μm * 4.8μm = 1200 VDC. In other words, the voltage can be selected according to the thickness of the metallized film during the specific test.

[0042] Of course, in the above vacuum settling step, the absolute vacuum level of the vacuum environment is less than or equal to 1 kPa.

[0043] Furthermore, in the potting compound etching step, after the potting compound sample is coated on the metallization layer of the metallization film, pressure is applied by a pressing block, which allows the potting compound to fully contact the metallization layer of the metallization film, and the corrosive substances in the potting compound migrate faster.

[0044] Specifically, the pressure applied to the aforementioned pressure block can be applied manually or by a drive component within a vacuum environment, depending on the actual needs.

[0045] Furthermore, in this embodiment, the pressure applied to the metallization layer of the metallization film by the above-mentioned pressing is greater than or equal to 50 kPa.

[0046] Example 2,

[0047] Unlike Example 1, in this example, the metallized film tested is a metallized film with edges left on both sides. That is, there is a certain gap between the side edges of the metallized coating and the side edges of the metallized film, and the gap width is 1.5mm-5mm. During the test, a voltage of 1000VDC / mm can be applied to the edges of the metallized film during the vacuum settling step. After that, in the test step, the corrosion of the metallized film is tested. Based on the corrosion on both sides of the edges of the metallized film, it can be clearly determined whether the potential corrosion in the potting compound has occurred as anodic corrosion or cathodic corrosion. Example 3,

[0048] Unlike Examples 1 and 2, the potting compound in this example is one of polyurethane potting compound, epoxy resin potting compound, or silicone potting compound.

[0049] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A method for testing the corrosivity of potting compound to metallized films, characterized in that, include, In the potting compound etching step, a certain mass of potting compound sample is taken and coated onto the metallization layer of the metallization film. The vacuum settling step involves placing the metallized film coated with the potting compound sample in a vacuum environment and settling it for 120-240 hours; during the settling process, a voltage is applied to the metallized film. The testing steps include testing the sheet resistance of the metallized thin film in a heated environment; in the vacuum settling step, the metallized thin film is heated during the settling process. The potting compound is one of polyurethane potting compound, epoxy resin potting compound, or silicone potting compound.

2. The method for testing the corrosivity of potting compound to metallized films as described in claim 1, characterized in that, In the aforementioned testing procedure, the temperature of the heating environment is 120°C. o C.

3. The method for testing the corrosivity of potting compound to metallized films as described in claim 1, characterized in that, In the test procedure, the temperature of the heating environment is 85±2℃ or 105±2℃.

4. The method for testing the corrosivity of potting compound to metallized films as described in claim 1, characterized in that, During the vacuum settling step, the voltage applied to the metallized thin film is 250VDC / μm.

5. The method for testing the corrosivity of potting compound to metallized films as described in any one of claims 1-4, characterized in that, In the potting compound etching step, the potting compound sample is coated onto the metallization layer of the metallization film and then pressure is applied by a pressure block.

6. The method for testing the corrosivity of potting compound to metallized films as described in claim 5, characterized in that, The pressure applied by the pressure block to the metallization layer of the metallized film is greater than or equal to 50 kPa.

7. The method for testing the corrosivity of potting compound to metallized films as described in any one of claims 1-4, characterized in that, During the vacuum settling step, the absolute vacuum level of the vacuum environment is less than or equal to 1 kPa.

8. The method for testing the corrosivity of potting compound to metallized films as described in any one of claims 1-3, characterized in that, The metallized film is a metallized film with edges left on both sides. During the vacuum settling step, a voltage of 1000VDC / mm is applied to the edges of the metallized film.