Cleaning method of gold terminal multilayer ceramic capacitor

Abstract

The invention belongs to the technical field of device cleaning, and particularly relates to a cleaning method of a gold terminal multilayer ceramic capacitor. According to the invention, through mixed cleaning of acetic acid and ethanol, inorganic and organic pollutants on the surface of the gold terminal multilayer ceramic capacitor can be effectively cleaned. The acetic acid can chemically react with part of alkaline impurities, metal oxides and part of organic dirt on the surface of a gold layer of the gold-terminal multilayer ceramic capacitor to convert the alkaline impurities, the metal oxides and the organic dirt into water-soluble or easy-to-clean substances; ethanol has good solubility and volatility, and has a good cleaning effect on organic pollutants such as oil stains and organic impurities on the surface of the multilayer ceramic capacitor; according to the method, ultrasonic waves are used in a combined mode, strong impact force and microjet are generated through the cavitation effect of the ultrasonic waves in liquid, inorganic and organic pollutants on the surface of the multi-layer ceramic capacitor are stripped and removed, micro-pollutants can be effectively removed through multi-stage rinsing, and the service life of the multi-layer ceramic capacitor is prolonged. Therefore, the purpose of cleaning the gold layer surface of the gold terminal multilayer ceramic capacitor is achieved.

Description

Technical Field

[0001] This invention belongs to the field of device cleaning technology, and specifically relates to a cleaning method for a gold-terminated multilayer ceramic capacitor. Background Technology

[0002] Gold-terminal multilayer ceramic capacitors (MLCCs) operate in harsh environments, requiring high cleanliness of their terminals during production, testing, packaging, transportation, and installation. However, during testing and other processes, contamination of the terminal electrode surfaces, including but not limited to copper oxide, is unavoidable. Therefore, the cleaning method for gold-terminal multilayer ceramic capacitors directly affects their appearance yield and product installation reliability.

[0003] Currently, the main cleaning methods for multilayer ceramic capacitors include the following: The first method is organic solvent cleaning: organic solvents such as ethanol or acetone have good solubility and volatility, and are effective at cleaning organic contaminants such as oil, fingerprints, and organic impurities from the surface of multilayer ceramic capacitors. After cleaning, the organic solvent evaporates quickly without leaving noticeable residue; however, its effectiveness in removing inorganic contaminants such as metal oxides is limited.

[0004] The second method is strong acid cleaning: strong acids such as hydrochloric acid, sulfuric acid, or nitric acid can remove inorganic contaminants such as metal oxides and rust from the surface of multilayer ceramic capacitors. However, strong acids are highly corrosive, and the concentration, cleaning temperature, and cleaning time of the strong acid must be strictly controlled. After strong acid cleaning, thorough neutralization and rinsing are necessary to prevent residual strong acid from corroding the multilayer ceramic capacitors and reducing product reliability.

[0005] The third method is strong alkaline cleaning: strong alkaline solutions such as sodium hydroxide or potassium hydroxide can remove acidic contaminants and grease from the surface of multilayer ceramic capacitors. However, after strong alkaline cleaning, thorough neutralization and rinsing are still necessary to remove residual strong alkaline solution and avoid adverse effects on the multilayer ceramic capacitors. Furthermore, strong alkaline cleaning may reduce product reliability.

[0006] In addition, the cleaning methods for the aforementioned multilayer ceramic capacitors all have the problem of significant environmental pollution, which is detrimental to the environment. Summary of the Invention

[0007] The purpose of this invention is to provide a cleaning method for gold-terminal multilayer ceramic capacitors. The method provided by this invention can effectively clean inorganic and organic contaminants in gold-terminal multilayer ceramic capacitors without being environmentally friendly or neutralized.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a cleaning method for gold-terminated multilayer ceramic capacitors, comprising the following steps: The gold-terminated multilayer ceramic capacitor was sequentially cleaned with ethanol, immersed in acetic acid, rinsed with acetic acid, washed with water, cleaned with ethanol, rinsed with ethanol, and dried. The acetic acid solution used for immersion had a mass concentration of 3.6-5%. The acetic acid rinsing and ethanol rinsing were performed under ultrasonic conditions.

[0009] Preferably, the first ethanol cleaning includes the following steps: shaking the gold-terminated multilayer ceramic capacitor in the first ethanol.

[0010] Preferably, the shaking time is 15 to 30 seconds.

[0011] Preferably, the soaking time in the acetic acid solution is 40 to 60 minutes.

[0012] Preferably, the temperature of the acetic acid rinsing solution is 40~60 ℃, and the holding time is 2~4 minutes; during the acetic acid rinsing solution, the ultrasonic frequency is 1 kHz.

[0013] Preferably, the second ethanol cleaning includes the following steps: immersing the gold-terminated multilayer ceramic capacitor in ethanol for rinsing.

[0014] Preferably, the rinsing is an up-and-down rinsing; the rinsing time is 14-16 seconds.

[0015] Preferably, in the ethanol rinsing, the frequency of the ultrasound is 1 kHz; and the ethanol rinsing time is 9 to 11 seconds.

[0016] Preferably, the ethanol rinsing is performed 4 times.

[0017] Preferably, the drying temperature is 148~152 ℃ and the heat preservation time is 3 hours.

[0018] This invention provides a cleaning method for gold-terminal multilayer ceramic capacitors. The method uses a mixture of acetic acid and ethanol at specific concentrations to effectively remove inorganic and organic contaminants from the surface of the gold-terminal multilayer ceramic capacitor, eliminating the need for neutralization and facilitating rinsing.

[0019] Acetic acid can chemically react with some alkaline impurities, metal oxides, and some organic dirt on the gold layer surface of gold-terminal multilayer ceramic capacitors, converting them into water-soluble or easily cleanable substances. Ethanol has good solubility and volatility, and has a good cleaning effect on oil stains and organic pollutants such as organic impurities on the surface of multilayer ceramic capacitors. This invention combines the use of ultrasound, utilizing the cavitation effect of ultrasound in liquids to generate strong impact force and micro-jet, so that inorganic and organic pollutants on the surface of multilayer ceramic capacitors are stripped and removed. Through multi-stage rinsing, microscopic pollutants can be effectively removed, thereby achieving the purpose of cleaning the gold layer surface of gold-terminal multilayer ceramic capacitors.

[0020] The cleaning method provided by this invention uses readily available, low-cost, non-toxic, and pollution-free reagents with a wide range of applications. It is suitable for cleaning various gold-terminal multilayer ceramic capacitors and surface-plated gold electronic components. Detailed Implementation

[0021] This invention provides a cleaning method for gold-terminated multilayer ceramic capacitors, comprising the following steps: The gold-terminated multilayer ceramic capacitor was sequentially cleaned with ethanol, immersed in acetic acid, rinsed with acetic acid, washed with water, cleaned with ethanol, rinsed with ethanol, and dried. The acetic acid solution used for immersion had a mass concentration of 3.6-5%. The acetic acid rinsing and ethanol rinsing were performed under ultrasonic conditions.

[0022] In this invention, the cleaning method can be applied to Class I and / or Class II porcelain.

[0023] This invention involves sequentially cleaning a gold-terminated multilayer ceramic capacitor with ethanol, immersing it in acetic acid, rinsing it with acetic acid, and washing it with water. In this invention, the first ethanol cleaning may include the following step: shaking the gold-terminated multilayer ceramic capacitor in the first ethanol.

[0024] In this invention, the first ethanol can be anhydrous ethanol; the shaking time can be 15-30 seconds, specifically 20 seconds or 25 seconds. This invention removes suspended impurities from the surface of the gold-terminated multilayer ceramic capacitor through cleaning with the first ethanol.

[0025] In this invention, the acetic acid solution used for soaking can be an aqueous acetic acid solution or white vinegar; the preparation method of the aqueous acetic acid solution may include the following steps: stirring and mixing acetic acid with a mass concentration of 36% and water; the water can be deionized water; the volume ratio of acetic acid to water can be 1:6.45~9, specifically 1:6.8, 1:7.5, 1:8 or 1:8.5; the stirring and mixing time can be 10 seconds.

[0026] In this invention, the acetic acid solution used for immersion has a mass concentration of 3.6-5%, specifically 4% or 4.5%. Using acetic acid solution of the above-mentioned mass concentration offers advantages such as simple operation, easy rinsing, no need for neutralization, low toxicity, and no pollution emissions. It also provides high cleaning efficiency, good material safety, and high process controllability.

[0027] In this invention, the acetic acid immersion time can be 40-60 minutes, specifically 43 minutes, 47 minutes, 50 minutes, 53 minutes, or 56 minutes. This invention removes adhering dirt from the ceramic body and terminal electrode surfaces of gold-terminated multilayer ceramic capacitors by immersion in acetic acid.

[0028] In this invention, the temperature of the acetic acid rinsing solution can be 40~60 ℃, specifically 45 ℃, 50 ℃ or 55 ℃, and the holding time can be 2~4 minutes, specifically 3 minutes; the equipment for acetic acid rinsing solution includes an ultrasonic cleaner; in the acetic acid rinsing solution, the frequency of the ultrasound can be 1 kHz.

[0029] Typical industrial cleaning frequencies range from 20 kHz to 1 MHz, while this invention uses a 1 kHz ultrasonic frequency, which has a stronger low-frequency cavitation effect: 1 kHz is a low-frequency ultrasonic frequency, with larger cavitation bubbles and stronger impact force when they burst (up to hundreds of atmospheres), effectively removing metal oxides (such as copper oxide) and hard inorganic contaminants from the surface of the gold terminals of gold-terminal multilayer ceramic capacitors. In contrast, high-frequency ultrasonic waves are more suitable for soft organic dirt and have a greater penetration depth: low-frequency sound waves attenuate less in liquids, allowing them to penetrate the electrode gaps or micropores of gold-terminal multilayer ceramic capacitors and remove hidden contaminants. This invention uses acetic acid solution for rinsing under low-frequency ultrasonic waves, further removing strongly adherent dirt from the ceramic body and terminal electrode surfaces of the gold-terminal multilayer ceramic capacitor.

[0030] In this invention, the water washing process may include the following steps: removing the gold-terminal multilayer ceramic capacitor, immersing the gold-terminal multilayer ceramic capacitor in water and agitating it before removing it; the water may be deionized water; the agitation time may be 15-30 seconds, specifically 20 seconds or 25 seconds. After water washing, the gold-terminal multilayer ceramic capacitor is placed in a nylon mesh to transfer it to the mesh. This invention, through water washing, dilutes the acetic acid remaining on the surface of the gold-terminal multilayer ceramic capacitor and removes dirt.

[0031] After rinsing the gold-terminal multilayer ceramic capacitor with water, the present invention further performs a second ethanol cleaning, ethanol rinsing, and drying on the gold-terminal multilayer ceramic capacitor. In the present invention, the second ethanol cleaning may include the following steps: immersing the gold-terminal multilayer ceramic capacitor in ethanol for rinsing. In the present invention, the volume of the ethanol may be no less than 200 mL; the ethanol may be anhydrous ethanol.

[0032] In this invention, the washing device can be a nylon mesh; the washing can be an up-and-down washing; the washing time can be 14-16 seconds, specifically 15 seconds.

[0033] In this invention, the equipment for ethanol rinsing can be an ultrasonic cleaner; the frequency of the ultrasonic waves during ethanol rinsing can be 1 kHz; the temperature of the ethanol rinsing can be room temperature, and the time can be 9 to 11 seconds, specifically 10 seconds.

[0034] In this invention, the ethanol rinsing can be performed four times. This invention removes acetic acid, deionized water, and dirt remaining on the surface of the gold-terminal multilayer ceramic capacitor through a second ethanol cleaning and ethanol rinsing.

[0035] In this invention, the drying equipment can be a drying oven and a beaker sealed with tin foil; the tin foil used in the beaker can have pores; the number of pores can be 5; the drying temperature can be 148~152 ℃, specifically 150 ℃, and the holding time can be 3 hours. This invention uses the above equipment to prevent dust and impurities from falling in during the drying process and contaminating the gold-terminal multilayer ceramic capacitor. This invention removes residual ethanol from the surface of the gold-terminal multilayer ceramic capacitor through drying.

[0036] To further illustrate the present invention, the following detailed description of the embodiments is provided in conjunction with the present invention, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1 This embodiment provides a cleaning method for gold-terminated multilayer ceramic capacitors, the specific steps of which are as follows: (1) Take acetic acid with a mass concentration of 36% in a beaker, mix it with deionized water at a volume ratio of 1:9 and stir continuously for 10 seconds to obtain an acetic acid solution with a mass concentration of 3.6%.

[0038] (2) Pour the gold terminal multilayer ceramic capacitor into another beaker, add anhydrous ethanol, shake the beaker for 15 seconds and then pour it out to remove the suspended impurities on the surface of the gold terminal multilayer ceramic capacitor.

[0039] (3) Pour the prepared acetic acid solution with a mass concentration of 3.6% into the beaker containing the gold terminal multilayer ceramic capacitor and soak for 50 minutes.

[0040] (4) Place the beaker containing the gold-terminated multilayer ceramic capacitor into the ultrasonic cleaner, set the ultrasonic frequency to 1 kHz, the temperature to 50 ℃, and the time to 3 minutes.

[0041] (5) Remove the beaker from the ultrasonic cleaner, discard the acetic acid solution, add deionized water to the beaker to submerge the gold-terminated multilayer ceramic capacitor, shake the beaker for 15 seconds, and then discard the deionized water. Use a nylon mesh to transfer the gold-terminated multilayer ceramic capacitor into the nylon mesh.

[0042] (6) Take a clean beaker, add 200 mL of anhydrous ethanol to the beaker, put the nylon mesh that supports the gold terminal multilayer ceramic capacitor into the ethanol beaker, the ethanol should cover the gold terminal multilayer ceramic capacitor, rinse it up and down for 15 seconds, and put it into an ultrasonic cleaner along with the beaker. The ultrasonic frequency is 1 kHz, the temperature is room temperature, and the time is 10 seconds.

[0043] (7) Prepare three beakers containing 200 mL of anhydrous ethanol. Then transfer the nylon mesh containing the gold-terminated multilayer ceramic capacitor to the new beakers and repeat step (6) until the four-stage rinsing is completed (i.e., a total of four ethanol rinsings are performed).

[0044] (8) Transfer the gold-terminated multilayer ceramic capacitor after four-stage rinsing to a clean beaker, cover the top of the beaker with clean tin foil, leaving 5 air holes, and place it stably in a drying oven to dry at 150 ℃ for 3 hours.

[0045] Example 2 This embodiment provides a cleaning method for gold-terminated multilayer ceramic capacitors, the specific steps of which are as follows: (1) Take 36% acetic acid in a beaker and mix it with deionized water by stirring continuously for 10 seconds to obtain a 5% acetic acid solution.

[0046] (2) Pour the gold terminal multilayer ceramic capacitor into another beaker, add anhydrous ethanol, shake the beaker for 30 seconds and then pour it out to remove suspended impurities on the surface of the gold terminal multilayer ceramic capacitor.

[0047] (3) Pour the prepared 5% acetic acid solution into the beaker containing the gold-terminated multilayer ceramic capacitor and soak for 40 minutes.

[0048] (4) Place the beaker containing the gold-terminated multilayer ceramic capacitor into the ultrasonic cleaner, set the ultrasonic frequency to 1 kHz, the temperature to 40 ℃, and the time to 2 minutes.

[0049] (5) Remove the beaker from the ultrasonic cleaner, discard the acetic acid solution, add deionized water to the beaker to submerge the gold-terminated multilayer ceramic capacitor, shake the beaker for 30 seconds, and then discard the deionized water. Use a nylon mesh to transfer the gold-terminated multilayer ceramic capacitor into the nylon mesh.

[0050] (6) Take a clean beaker, add 200 mL of anhydrous ethanol to the beaker, put the nylon mesh that supports the gold terminal multilayer ceramic capacitor into the ethanol beaker, the ethanol should cover the gold terminal multilayer ceramic capacitor, rinse it up and down for 14 seconds, and put it into an ultrasonic cleaner along with the beaker. The ultrasonic frequency is 1 kHz, the temperature is room temperature, and the time is 9 seconds.

[0051] (7) Prepare three beakers containing 200 mL of anhydrous ethanol. Then transfer the nylon mesh containing the gold-terminated multilayer ceramic capacitor to the new beakers and repeat step (6) until the four-stage rinsing is completed.

[0052] (8) Transfer the gold-terminated multilayer ceramic capacitor after four-stage rinsing to a clean beaker, cover the top of the beaker with clean tin foil, leaving 5 air holes, and place it stably in a drying oven to dry at 148 ℃ for 3 hours.

[0053] Example 3 This embodiment provides a cleaning method for gold-terminated multilayer ceramic capacitors, the specific steps of which are as follows: (1) Take acetic acid with a mass concentration of 36% in a beaker and mix it with deionized water by stirring continuously for 10 seconds to obtain an acetic acid solution with a mass concentration of 4.5%.

[0054] (2) Pour the gold terminal multilayer ceramic capacitor into another beaker, add anhydrous ethanol, shake the beaker for 25 seconds and then pour it out to remove suspended impurities on the surface of the gold terminal multilayer ceramic capacitor.

[0055] (3) Pour the prepared acetic acid solution with a mass concentration of 4.5% into the beaker containing the gold terminal multilayer ceramic capacitor and soak for 60 minutes.

[0056] (4) Place the beaker containing the gold-terminated multilayer ceramic capacitor into the ultrasonic cleaner, set the ultrasonic frequency to 1 kHz, the temperature to 60 ℃, and the time to 4 minutes.

[0057] (5) Remove the beaker from the ultrasonic cleaner, discard the acetic acid solution, add deionized water to the beaker to submerge the gold-terminated multilayer ceramic capacitor, shake the beaker for 25 seconds, and then discard the deionized water. Use a nylon mesh to transfer the gold-terminated multilayer ceramic capacitor into the nylon mesh.

[0058] (6) Take a clean beaker, add 200 mL of anhydrous ethanol to the beaker, put the nylon mesh that supports the gold terminal multilayer ceramic capacitor into the ethanol beaker, the ethanol should cover the gold terminal multilayer ceramic capacitor, rinse it up and down for 16 seconds, and put it into an ultrasonic cleaner along with the beaker. The ultrasonic frequency is 1 kHz, the temperature is room temperature, and the time is 11 seconds.

[0059] (7) Prepare three beakers containing 200 mL of anhydrous ethanol. Then transfer the nylon mesh containing the gold-terminated multilayer ceramic capacitor to the new beakers and repeat step (6) until the four-stage rinsing is completed.

[0060] (8) Transfer the gold-terminated multilayer ceramic capacitor after four-stage rinsing to a clean beaker, cover the top of the beaker with clean tin foil, leaving 5 air holes, and place it stably in a drying oven to dry at 152 ℃ for 3 hours.

[0061] Test Example 1 The removal effects of contaminants (copper oxide, organic residues) on the surface of gold-terminal multilayer ceramic capacitors were tested on Example 1 and the control group (pure ethanol cleaning or strong acid cleaning by traditional methods, and no cleaning). The test methods were as follows: (1) Contaminant simulation: The gold-terminal multilayer ceramic capacitor was immersed in a suspension containing copper oxide (CuO) powder for 1 hour to simulate the contamination of the test tooling; (2) Cleanliness detection: The surface morphology was observed by scanning electron microscopy (SEM) to observe the contaminant residues on the surface of the gold terminals, and the elemental analysis was performed by energy dispersive spectroscopy (EDS) to detect the Cu element content (wt%). The specific cleaning methods and parameters are shown in Table 1, and the test results are shown in Table 2.

[0062] Table 1 Cleaning methods and parameters

[0063] Table 2 Test Results

[0064] As can be seen from Table 2, the cleaning method provided by the present invention is significantly better than the traditional method in terms of Cu residue, and there is no corrosion damage.

[0065] As can be seen from the above embodiments, the method provided by the present invention can effectively clean inorganic and organic contaminants from gold-terminal multilayer ceramic capacitors while being environmentally friendly and free from neutralization.

[0066] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cleaning method for a gold-terminated multilayer ceramic capacitor, characterized in that, Includes the following steps: The gold-terminated multilayer ceramic capacitor was sequentially cleaned with ethanol, immersed in acetic acid, rinsed with acetic acid, washed with water, cleaned with ethanol, rinsed with ethanol, and dried. The acetic acid solution used for soaking has a mass concentration of 3.6% to 5%. The acetic acid rinsing and ethanol rinsing were performed under ultrasonic conditions.

2. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1, characterized in that, The first ethanol cleaning includes the following steps: The gold-terminated multilayer ceramic capacitor was shaken in the first ethanol.

3. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 2, characterized in that, The shaking lasts for 15 to 30 seconds.

4. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1, characterized in that, The acetic acid solution is used for soaking for 40 to 60 minutes.

5. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1 or 2, characterized in that, The acetic acid solution is rinsed at a temperature of 40~60 ℃ for 2~4 minutes. During the acetic acid rinsing, the ultrasonic frequency is 1 kHz.

6. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1, characterized in that, The second ethanol cleaning includes the following steps: The gold-terminated multilayer ceramic capacitor was rinsed by immersing it in ethanol.

7. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 6, characterized in that, The rinsing is described as an up-and-down rinsing process; The rinsing time is 14-16 seconds.

8. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1, characterized in that, During the ethanol rinsing, the frequency of the ultrasound is 1 kHz; The ethanol rinsing time is 9-11 seconds.

9. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1 or 8, characterized in that, The ethanol rinsing was performed four times.

10. The cleaning method for a gold-terminated multilayer ceramic capacitor according to claim 1, characterized in that, The drying temperature is 148~152 ℃, and the holding time is 3 hours.

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