Method for detecting corrosion resistance of rubber stopper

Abstract

A kind of detection method of corrosion resistance of rubber plug, comprising the following steps: 1) the rubber plug is placed in electrolyte and soaked for 3-10 hours;2) take the electrolyte in step 1);Take anode needle and cathode needle, so that the aluminum tongue of anode needle and cathode needle is immersed in electrolyte;3) anode needle connects power positive, cathode needle connects power negative;Apply the direct current voltage matching with the highest voltage of electrolyte;Last 20-60 minutes;4) wipe the electrolyte on the surface of anode needle, check whether there is corrosion and blackening phenomenon in the position of anode needle aluminum tongue and aluminum stem with magnifying glass or microscope;If yes, it is unqualified.The detection method of corrosion resistance of rubber plug of the application greatly shortens the time;Traditional method needs 1000 hours or more high temperature durability / load test, and the present scheme can be completed in one day, and the efficiency is improved by hundreds of times.

Description

Technical Field

[0001] This invention relates to a method for testing rubber stoppers for aluminum electrolytic capacitors, and more particularly to a method for testing the corrosion resistance of rubber stoppers. Background Technology

[0002] Aluminum electrolytic capacitors are indispensable key components in electronic devices, widely used in power supplies, consumer electronics, industrial control, and new energy vehicles. Their core performance characteristics (such as capacitance stability, equivalent series resistance (ESR), leakage current, and lifespan) depend not only on the performance of the anode foil and electrolyte but also closely on the chemical compatibility of the rubber stopper. The rubber stopper is typically made of butyl rubber (IIR) or ethylene propylene diene monomer (EPDM), primarily functioning to seal the electrolyte inside the capacitor, preventing leakage and providing some explosion-proof functionality. However, the electrolyte is usually composed of highly polar solvents (such as γ-butyrolactone and ethylene glycol), ammonium carboxylate salts, and additives, exhibiting high chemical activity. Under long-term high-temperature and high-pressure operating conditions, the electrolyte may permeate the rubber stopper, causing it to swell, harden, or degrade its molecular chains, leading to serious problems such as seal failure, electrolyte evaporation, or capacitor explosion.

[0003] Currently, the mainstream industry certification method for the compatibility of rubber stoppers with electrolytes is to fabricate them into complete aluminum electrolytic capacitor samples and then subject them to long-term high-temperature load / durability tests. However, this method has the following significant drawbacks: Long testing cycle: Traditional high temperature load / durability testing usually takes hundreds to thousands of hours, which cannot meet the needs of rapid research and development and mass production, and seriously slows down the product launch time.

[0004] High certification costs: Each test requires the preparation of a complete capacitor sample, resulting in high material and manufacturing costs.

[0005] Multiple interfering factors: Test results are affected by various factors such as aluminum foil corrosion, electrolytic paper aging, and packaging process, making it difficult to assess the failure mechanism of the rubber stopper alone.

[0006] Lack of early screening methods: If the compatibility between the rubber stopper and the electrolyte cannot be quickly determined during the material development stage, a large number of ineffective formulations may enter later testing, resulting in a waste of resources.

[0007] Current technologies primarily assess the electrolyte resistance of rubber stoppers through simple immersion tests. However, these methods cannot simulate the electrochemical corrosion environment under actual working conditions and lack verification of their correlation with capacitor performance. Therefore, there is an urgent need for a rapid and accurate method for rubber stopper certification that can predict long-term compatibility in a short time, thereby significantly shortening the R&D cycle and reducing trial-and-error costs. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for testing the corrosion resistance of rubber stoppers.

[0009] To solve the above-mentioned technical problems, the technical solution proposed by this invention is: a method for testing the corrosion resistance of rubber stoppers, comprising the following steps: 1) Soak the rubber stopper in the electrolyte for 3-10 hours; 2) Take the electrolyte from step 1); place it in the detection container; take the anode and cathode leads, and immerse the aluminum tongues of the anode and cathode leads in the electrolyte; 3) Connect the anode pin to the positive terminal of the power supply and the cathode pin to the negative terminal of the power supply; apply a DC voltage that matches the highest withstand voltage of the electrolyte; continue for 20-60 minutes; the temperature is 105℃~130℃; 4) Wipe the electrolyte off the surface of the anode guide pin and use a magnifying glass or microscope to check for corrosion and blackening at the aluminum tongue and stem of the anode guide pin; if so, it is unqualified.

[0010] In the above-mentioned method for testing the corrosion resistance of rubber stoppers, preferably, in step 1), the weight of the rubber stopper is 10%-40% of the weight of the electrolyte.

[0011] In the above-mentioned method for testing the corrosion resistance of rubber plugs, preferably, in step 3), the anode guide needle and the cathode guide needle are fixed by the same rubber plug as in step 1).

[0012] In the above-mentioned method for testing the corrosion resistance of rubber stoppers, preferably, in step 3), the aluminum stems of the anode and cathode guide pins are fixed inside the lead hole of the rubber stopper.

[0013] In the above-mentioned method for testing the corrosion resistance of rubber stoppers, preferably, the rubber stopper immersed in the electrolyte in step 1) is cut into granules.

[0014] Compared with existing technologies, the advantages of this invention are as follows: the method for testing the corrosion resistance of rubber stoppers is significantly faster; traditional methods require more than 1000 hours of high-temperature durability / load testing, while this method can be completed in just one day, improving efficiency by hundreds of times. Furthermore, the testing method of this invention does not require the fabrication of a complete capacitor, only a rubber stopper, electrolyte, and a simple testing device, saving significant material and manufacturing costs. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the electrochemical corrosion test in the method for detecting the corrosion resistance of rubber stoppers in Example 1. Detailed Implementation

[0016] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0017] It should be noted that when a component is described as being "fixed to, attached to, connected to or connected to" another component, it can be directly fixed to, attached to, connected to or connected to the other component, or it can be indirectly fixed to, attached to, connected to or connected to the other component through other intermediate connectors.

[0018] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention. Example 1

[0019] A method for testing the corrosion resistance of rubber stoppers includes the following steps: 1) Immerse the rubber stopper in the electrolyte for 3-10 hours; the weight of the rubber stopper should be 10%-40% of the weight of the electrolyte. In this embodiment, the rubber stopper used for immersion is cut into granules, which can accelerate the swelling rate of the rubber stopper. In this embodiment, the temperature during immersion is 85℃-130℃, and the high temperature can accelerate the penetration of the electrolyte, simulating the swelling effect under long-term use.

[0020] 2) Take the electrolyte from step 1); place it in the detection container; take the anode and cathode leads, and immerse their aluminum tongues in the electrolyte. The detection container can be a beaker or a large aluminum shell.

[0021] 3) such as Figure 1 As shown, the anode pin is connected to the positive terminal of the power supply, and the cathode pin is connected to the negative terminal; a DC voltage matching the highest withstand voltage of the electrolyte is applied; this is continued for 20-60 minutes; the temperature is between 105℃ and 130℃, forcibly accelerating the corrosion of the aluminum stem and / or aluminum tongue by the electrolyte. In this embodiment, in step 3), the anode pin and cathode pin are fixed by the same rubber plug as in step 1); the aluminum stems of the anode pin and cathode pin are fixed inside the lead hole of the rubber plug.

[0022] In this embodiment, the anode and cathode leads are fixed with rubber plugs to restore the aluminum electrolytic capacitor to its state during use as much as possible.

[0023] The detection method in this embodiment directly simulates actual working conditions through electrochemical accelerated corrosion, which is closer to the real failure mode than a simple immersion test.

[0024] 4) Wipe the electrolyte off the surface of the anode guide pin and use a magnifying glass or microscope to check for corrosion and blackening at the aluminum tongue and stem of the anode guide pin; if so, it is unqualified.

[0025] In this embodiment, after the rubber stopper is soaked in the electrolyte in step 1), if the rubber stopper and electrolyte have poor compatibility, the components inside the rubber stopper will enter the electrolyte through the swelling effect. After the electrochemical corrosion in step 3), the leakage current is the largest at the aluminum stem location. At the aluminum stem location of the anode needle, harmful ions from the rubber stopper enter the electrolyte through the swelling effect. Then, under the action of the electric field, harmful negative ions accumulate at the anode aluminum stem. Under the combined action of prolonged high temperature and electric field, the harmful ions will accelerate the erosion of the oxide film at the aluminum stem, resulting in local flash fire or local discharge. The high temperature generated by the local flash fire will cause the electrolyte at the interface to carbonize, ultimately causing the aluminum stem to turn black. At the same time, slight pitting will also appear on the surface of the aluminum stem. To verify this, a comparative experiment was set up in this embodiment. In the comparative experiment, the rubber stopper was not soaked in the electrolyte, but everything else was the same as in this embodiment. After the electrochemical corrosion in step 3), the electrolyte alone would not cause the aluminum stem location of the anode needle to turn black. In other words, the blackening of the aluminum stem of the anode guide pin can only be caused by poor compatibility between the rubber stopper and the electrolyte, allowing components of the rubber stopper to enter the electrolyte.

[0026] When the rubber stopper is well-compatible with the electrolyte, very little of the components inside the rubber stopper will enter the electrolyte through the swelling effect. After the electrochemical corrosion in step 3), the aluminum stem will not accumulate rubber stopper components and will not turn black.

[0027] The method for testing the corrosion resistance of rubber stoppers in this embodiment significantly reduces the time required compared to traditional high-temperature durability / load tests that require over 1000 hours, completing the test in just one day. Furthermore, this method eliminates the need for manufacturing complete capacitors, requiring only rubber stoppers, electrolyte, and a simple testing apparatus, thus saving substantial material and manufacturing costs. Additionally, this testing method is suitable for rapid screening: it allows for quick verification of the compatibility between different rubber stoppers and electrolytes during the material development stage, preventing ineffective formulations from entering mass production testing.

Claims

1. A method for testing the corrosion resistance of rubber stoppers, characterized in that, Includes the following steps: 1) Soak the rubber stopper in the electrolyte for 3-10 hours; 2) Take the electrolyte from step 1); place it in the detection container; take the anode and cathode leads, and immerse the aluminum tongues of the anode and cathode leads in the electrolyte; 3) Connect the anode pin to the positive terminal of the power supply and the cathode pin to the negative terminal of the power supply; apply a DC voltage that matches the highest withstand voltage of the electrolyte; continue for 20-60 minutes; the temperature is 105℃~130℃; 4) Wipe the electrolyte off the surface of the anode guide pin and use a magnifying glass or microscope to check for corrosion and blackening at the aluminum tongue and stem of the anode guide pin; if so, it is unqualified.

2. The method for testing the corrosion resistance of rubber stoppers according to claim 1, characterized in that: In step 1), the weight of the rubber stopper is 10%-40% of the weight of the electrolyte.

3. The method for testing the corrosion resistance of rubber stoppers according to claim 1, characterized in that: In step 3), the anode guide needle and the cathode guide needle are fixed by the same rubber plug as in step 1).

4. The method for testing the corrosion resistance of rubber stoppers according to claim 3, characterized in that: In step 3), the aluminum stems of the anode and cathode guide pins are fixed inside the lead hole of the rubber plug.

5. The method for testing the corrosion resistance of rubber stoppers according to claim 3, characterized in that: In step 1), the rubber stopper immersed in the electrolyte is cut into granules.

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