Defoaming method of MLCC ceramic slurry

Abstract

The invention relates to a defoaming method for MLCC ceramic slurry, and the method comprises the following steps: determining the number of defoaming stages and the initial operation parameters of each defoaming stage, the initial operation parameters comprising stage duration, vacuum degree and stirring speed; wherein the defoaming stage comprises a first pressure state stage and a second pressure state stage which are alternately executed; the vacuum degree of the first pressure state stage is normal pressure, and the vacuum degree of the second pressure state stage is smaller than or equal to a preset vacuum degree threshold value; and controlling the defoaming device to execute the defoaming operation of each defoaming stage in sequence, wherein the operation of each stage is controlled based on the corresponding initial operation parameter. According to the defoaming method of the MLCC ceramic slurry disclosed by the embodiment of the invention, tiny bubbles are efficiently removed in a vacuum stage, and incomplete defoaming or particle aggregation caused by out-of-control viscosity in single-stage treatment is avoided; through the alternate design, bubbles of different sizes can be released step by step, the viscosity change can be controlled, and finally the bubble removing efficiency and the product quality of the MLCC are improved.

Description

Technical Field

[0001] This application relates to the technical field of defoaming of chip multi-layer ceramic capacitors, and particularly to a method for defoaming MLCC ceramic slurry. Background Art

[0002] In the manufacturing process of chip multi-layer ceramic capacitors (MLCCs), ceramic slurry is a key raw material, and the removal of internal bubbles directly affects the reliability and electrical performance of the device. Traditional defoaming processes mainly rely on the combination of mechanical stirring and vacuum treatment, but in actual applications, there are problems of strong manual dependence and low efficiency. Traditional technologies require operators to monitor the defoaming state in real time and record parameters, resulting in high labor costs and quality fluctuations easily caused by human errors. Especially in the treatment of high-viscosity ceramic slurries (such as ceramic slurries with a solid content > 60%), the bubble release speed is slow, further prolonging the manual intervention cycle. Summary of the Invention

[0003] Based on this, this application provides a method for defoaming MLCC ceramic slurry that can solve the above technical problems.

[0004] The above object of this application is achieved through the following technical solutions:

[0005] This application provides a method for defoaming MLCC ceramic slurry, including the following steps:

[0006] Determine the number of defoaming stages and the initial operating parameters of each defoaming stage, where the initial operating parameters include stage duration, vacuum degree, and stirring speed; where:

[0007] The defoaming stage includes an alternately executed first pressure state stage and a second pressure state stage; the vacuum degree of the first pressure state stage is normal pressure, and the vacuum degree of the second pressure state stage is less than or equal to a preset vacuum degree threshold;

[0008] Control the defoaming device to sequentially perform the defoaming operations of each defoaming stage, and the operation of each stage is controlled based on the corresponding initial operating parameters.

[0009] In an exemplary embodiment, determining the number of defoaming stages and the initial operating parameters of each defoaming stage includes:

[0010] Detect the initial viscosity of the ceramic slurry;

[0011] Determine the number of defoaming stages and the initial operating parameters of each defoaming stage according to the initial viscosity; where the number of defoaming stages is positively correlated with the initial viscosity, and the higher the initial viscosity, the more the number of divided defoaming stages.

[0012] In an exemplary embodiment, the following steps are further included:

[0013] At the start of each defoaming stage operation, detect the real-time viscosity of the ceramic slurry, and adjust the initial operation parameters of this stage according to the real-time viscosity.

[0014] In an exemplary embodiment, the stirring mechanism of the defoaming device includes an electric motor, and the method further includes the following steps:

[0015] During the operation of each defoaming stage, obtain the current value of the electric motor in real time;

[0016] According to the comparison result between the current value and a preset threshold, dynamically adjust the duration of the current stage: if the current value continuously exceeds the preset upper threshold, shorten the duration of the current stage; if the current value continuously is lower than the preset lower threshold, extend the duration of the current stage.

[0017] In an exemplary embodiment, the following steps are further included:

[0018] If the rising change rate of the current value is greater than a preset change threshold, reduce the vacuum degree and / or stirring speed of the current stage.

[0019] In an exemplary embodiment, the number of defoaming stages is four, and the execution order is successively the first pressure state stage, the second pressure state stage, the first pressure state stage, and the second pressure state stage.

[0020] In an exemplary embodiment, the successive durations of the four pressure state stages are 60 - 100 min, 100 - 120 min, 60 - 100 min, and 240 min - 280 min.

[0021] In an exemplary embodiment, the stirring speed is greater than 0 and less than or equal to 20 rpm.

[0022] The present application has the following beneficial effects:

[0023] For the defoaming method of the MLCC ceramic slurry in the embodiment of the present application, aiming at the characteristics that high-viscosity ceramic slurry is prone to a sudden increase in viscosity due to solvent volatilization under continuous vacuum, loss of fluidity, and difficulty in completely removing bubbles, through alternating staged treatment of normal pressure and vacuum, the physical properties of the ceramic slurry can be stabilized in the normal pressure stage and large bubbles can be naturally escaped; in the vacuum stage, micro-bubbles can be efficiently removed, avoiding incomplete defoaming or particle agglomeration caused by viscosity out of control in single-stage treatment; through this alternating design, the present application can gradually release bubbles of different sizes and control the viscosity change, ultimately improving the defoaming efficiency and the product quality of MLCC. Description of the Drawings

[0024] Figure 1 Schematic structural diagram of a defoaming device in an exemplary embodiment;

[0025] Figure 2 Schematic diagram of the steps of a method for defoaming MLCC ceramic slurry in an exemplary embodiment;

[0026] Figure 3 Schematic diagram of the steps of a method for defoaming MLCC ceramic slurry in an exemplary embodiment.

[0027] Explanation of the reference numerals in the drawings:

[0028] 10. Touch screen; 20. PLC; 30. Stirring motor; 40. Defoaming tank; 50. Stirring paddle; 60. Vacuum valve. Detailed implementation manners

[0029] To make the above objects, features, and advantages of the present application more apparent and understandable, the following provides a detailed description of the specific implementation manners of the present application. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0030] In the description of the present application, it should be understood that if terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application.

[0031] In the present application, unless otherwise clearly specified and defined, if terms such as "installation", "connection", "connection", "fixation", etc. appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] In this application, unless otherwise clearly stipulated and defined, when a first feature is described as being "on" or "under" a second feature or the like, it may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" or "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" or "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature has a lower horizontal height than the second feature.

[0033] In addition, the terms "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application in this specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0035] In view of the technical problems in the background art, this application provides a defoaming method for MLCC ceramic slurry, which is applied to a defoaming device, such as Figure 1As shown, in one embodiment, the defoaming device includes a touch screen 10, a PLC 20, a stirring motor 30, a defoaming tank 40, a stirring paddle 50, and a vacuum valve 60. Among them, the defoaming tank 40 is used to hold the ceramic slurry of MLCC; the touch screen 10 is used to provide a human-machine interaction interface, receive the process parameters set by the user (such as initial viscosity, number of stages, vacuum degree of each stage, stirring speed, and duration), and display the defoaming process data in real time (such as current stage, remaining time, real-time viscosity, current value, vacuum degree, etc.), and provide abnormal alarm prompts. The PLC 20 (programmable logic controller) serves as the control core, which is used to analyze the parameters input by the touch screen 10, generate stage control instructions to dynamically adjust the rotation speed of the stirring motor 30 and the vacuum degree of the defoaming tank 40; the stirring paddle 50 is arranged in the defoaming tank 40, and the stirring motor 30 drives the stirring paddle 50 to rotate at a set speed to generate a shearing force to promote the bubbles in the ceramic slurry in the defoaming tank 40 to escape. The defoaming tank is connected to a vacuum pump (not shown) through a vacuum pipeline, and the pressure in the defoaming tank 40 is switched (atmospheric pressure ←→ vacuum) by opening or closing the vacuum valve 60 on the vacuum pipeline. In one embodiment, the stirring motor 30 is an electric motor, and the defoaming device further includes a current detection device for detecting the current value of the stirring motor. The current detection device is communicatively connected to the PLC to transmit current data in real time. In other embodiments, the stirring motor 30 can also be a pneumatic motor. In Figure 1 this example, the PLC 20 is also used to control the opening or closing of the vacuum valve 60.

[0036] Such as Figure 2 shown, in one embodiment, the defoaming method of the MLCC ceramic slurry of the present application includes the following steps:

[0037] S201: Determine the number of defoaming stages and the initial operating parameters of each defoaming stage. The initial operating parameters include stage duration, vacuum degree, and stirring speed; where: the defoaming stage includes a first pressure state stage and a second pressure state stage that are alternately executed; the vacuum degree of the first pressure state stage is atmospheric pressure, and the vacuum degree of the second pressure state stage is less than or equal to a preset vacuum degree threshold.

[0038] S202: Control the defoaming device to sequentially perform the defoaming operations of each defoaming stage, and the operation of each stage is controlled based on the corresponding initial operating parameters.

[0039] In this embodiment, the entire defoaming process is divided into multiple continuously operating defoaming stages. In each defoaming stage, the defoaming device is controlled to operate with the initial operating parameters set for this defoaming stage to perform defoaming operations.

[0040] The initial operating parameters of this embodiment can be set manually or automatically obtained from past empirical values. Among them, the stage duration refers to the operation duration of each degassing stage (e.g., 60 - 100 minutes for the atmospheric pressure stage and 100 - 300 minutes for the vacuum stage); the vacuum degree refers to the negative pressure intensity inside the degassing tank (e.g., ≤ -95 kPa in the second pressure state stage); the stirring speed refers to the rotational speed of the blades of the stirring paddle inside the degassing tank (e.g., 5 - 20 rpm). Among them, the preset vacuum degree threshold can be set to -95 kPa. The vacuum degree being less than or equal to the preset vacuum degree threshold means that the value of the vacuum degree is lower than -95 kPa, for example, -101 kPa.

[0041] In this embodiment, the degassing process includes pressure state stages that are executed alternately:

[0042] The first pressure state stage (atmospheric pressure): Stir the ceramic slurry under atmospheric pressure. The surface pressure of the ceramic slurry is balanced with the atmospheric pressure, promoting the natural escape of large bubbles; it can reduce the number of bubbles to be processed in the subsequent vacuum stage and avoid complex degassing problems caused by the rapid expansion of small bubbles due to the sudden drop in pressure in a vacuum environment.

[0043] The second pressure state stage (vacuum): Stir the ceramic slurry under negative pressure to accelerate the expansion and rupture of microbubbles.

[0044] Among them, the first pressure state stage is executed first, and then the second pressure state stage is executed, and so on, until the last second pressure state stage is continuously executed alternately. Among them, the number of executions of the first pressure state stage and the second pressure state stage is at least one, that is, the entire degassing process includes at least two pressure state stages.

[0045] In this embodiment, executing the first pressure state stage first can slowly release some bubbles, avoiding premature thickening of the ceramic slurry due to vacuum treatment in the initial stage and affecting the degassing efficiency of subsequent stages. If the first pressure state stage and the second pressure state stage are executed multiple times, the first pressure state stage after the second pressure state stage can relieve the viscosity pressure of the ceramic slurry and reduce the viscosity, so that the next second pressure state stage can more thoroughly remove the remaining bubbles.

[0046] For the degassing method of the MLCC ceramic slurry in the embodiment of the present application, aiming at the characteristics that high-viscosity ceramic slurry is prone to a sudden increase in viscosity and loss of fluidity due to solvent volatilization under continuous vacuum, and it is difficult to completely remove bubbles, through alternating staged treatment of atmospheric pressure and vacuum, the physical properties of the ceramic slurry can be stabilized and large bubbles can be promoted to escape naturally in the atmospheric pressure stage; in the vacuum stage, microbubbles can be efficiently removed, avoiding incomplete degassing or particle agglomeration caused by viscosity out of control in single-stage treatment; through this alternating design, the present application can gradually release bubbles of different sizes and control the viscosity change, ultimately improving the degassing efficiency and the product quality of MLCC.

[0047] In a preferred embodiment, as Figure 3 shown, determine the number of defoaming stages and the initial operating parameters of each defoaming stage, including:

[0048] S301: Detect the initial viscosity of the ceramic slurry;

[0049] S302: Determine the number of defoaming stages and the initial operating parameters of each defoaming stage according to the initial viscosity; wherein, the number of defoaming stages is positively correlated with the initial viscosity, and the higher the initial viscosity, the more defoaming stages are divided.

[0050] In this embodiment, the flow resistance of the ceramic slurry before defoaming can be measured by a viscometer to quantify its initial consistency (unit: cps); the specific measurement method can be on-line measurement, or after sampling the ceramic slurry, off-line measurement is carried out externally.

[0051] The positive correlation logic between the number of defoaming stages and the initial viscosity in this embodiment is specifically manifested as: the higher the initial viscosity → the worse the fluidity of the ceramic slurry → more stages are required for step-by-step defoaming.

[0052] At the same time, after determining the number of defoaming stages, the present application can also determine the initial operating parameters of each defoaming stage according to the initial viscosity of the ceramic slurry. Specifically, the correspondence between the initial viscosity of the present application, the number of defoaming stages, and the initial operating parameters of each defoaming stage can be determined according to empirical values, that is, after performing defoaming operations on ceramic slurries with different initial viscosities in different numbers of stages, record the operating parameters of each defoaming stage during each defoaming operation, and finally, according to the results after multiple tests, select the best operating parameters as empirical values to set the initial operating parameters.

[0053] For high-viscosity ceramic slurries, in this embodiment, normal pressure (releasing large bubbles) and vacuum (breaking small bubbles) are alternately applied in stages to avoid viscosity runaway caused by continuous vacuum; the higher the viscosity, the more stages, and the normal pressure recovery period is extended to prevent premature thickening of the ceramic slurry; while improving the defoaming rate, the defoaming time is saved.

[0054] After setting the subsequent defoaming stages and initial operating parameters according to the initial viscosity and running, control the operation of the defoaming device. The present application determines the number of stages and the initial operating parameters according to the initial viscosity, that is, it is desired to control the defoaming device to defoam according to the defoaming process corresponding to the empirical values. To check whether the defoaming process runs according to the process corresponding to the empirical values, in a preferred embodiment, the defoaming method for MLCC ceramic slurry of the present application further includes the following steps:

[0055] At the start of each defoaming stage operation, the real-time viscosity of the ceramic slurry is detected, and based on the real-time viscosity, the initial operation parameters of this stage are adjusted.

[0056] In this embodiment, through the real-time viscosity detection and parameter adjustment at the beginning of each stage, the actual state of the ceramic slurry is dynamically adapted to ensure that the defoaming efficiency of each stage is consistent with the preset empirical value, and to avoid parameter deviation caused by batch differences or environmental fluctuations. Among them, the judgment logic for adjusting the initial operation parameters according to the implemented viscosity refers to the above empirical value setting and judgment method.

[0057] Since it is not convenient to take samples to detect the viscosity of the ceramic slurry during the defoaming process and the possible deviation of the online detection method is relatively large, therefore, in another preferred embodiment, the defoaming method for the MLCC ceramic slurry of the present application further includes the following steps:

[0058] During the operation of each defoaming stage, the current value of the stirring mechanism of the defoaming device is obtained in real time;

[0059] According to the comparison result between the current value and the preset threshold value, the duration of the current stage is dynamically adjusted: if the current value continuously exceeds the preset upper threshold value, the duration of the current stage is shortened; if the current value continuously is lower than the preset lower threshold value, the duration of the current stage is extended.

[0060] Among them, the judgment logic for adjusting the initial operation parameters according to the current value of the stirring mechanism refers to the above empirical value setting and judgment method.

[0061] In Figure 1 the example, the stirring mechanism corresponds to the stirring motor 30. Under the same other conditions, the greater the viscosity of the ceramic slurry, the greater the resistance received by the stirring paddle 50, and the greater the current of the stirring motor 30. Therefore, in this embodiment, by monitoring the current value of the stirring mechanism in real time, it is judged from the side whether the viscosity of the ceramic slurry during the defoaming process reaches the set threshold value. If the current is large, it means that the viscosity is too high, then the operation time of the current stage (usually the second pressure state stage) is shortened, and the next first pressure state stage is entered as soon as possible to reduce the viscosity of the ceramic slurry.

[0062] This embodiment realizes real-time deviation correction through the current feedback of the stirring mechanism, offsets interference factors such as batch differences and temperature fluctuations, and improves process consistency.

[0063] In another preferred embodiment, the defoaming method for the MLCC ceramic slurry of the present application further includes the following steps:

[0064] If the rising change rate of the current value is greater than the preset change threshold value, the vacuum degree and / or the stirring speed of the current stage are reduced.

[0065] In this embodiment, during the stage of early switching when the current surges abnormally, the risk of motor overload is reduced and the equipment lifespan is extended.

[0066] In a specific embodiment, the number of defoaming stages is four, and the execution sequence is successively the first pressure state stage, the second pressure state stage, the first pressure state stage, and the second pressure state stage, with continuous operation between each pressure state stage.

[0067] The duration of the first first pressure state stage is 60 - 100 min, the duration of the first second pressure state stage is 100 - 120 min, the duration of the second first pressure state stage is 60 - 100 min, and the duration of the second second pressure state stage is 240 min - 280 min. The stirring speed is greater than 0 and less than or equal to 20 rpm.

[0068] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0069] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limitations on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A method for defoaming MLCC ceramic slurry, characterized in that: The following steps are involved: Determine the number of defoaming stages and the initial operating parameters of each defoaming stage, the initial operating parameters including stage duration, vacuum degree and stirring speed; wherein: The debubbling stage includes a first pressure state stage and a second pressure state stage which are performed alternately; the vacuum degree of the first pressure state stage is normal pressure, and the vacuum degree of the second pressure state stage is less than or equal to a preset vacuum degree threshold; The defoaming device is controlled to perform defoaming operations in each defoaming stage in sequence, and the operation of each stage is controlled based on the corresponding initial operating parameters.

2. The defoaming method of MLCC ceramic slurry according to claim 1, characterized in that: Determine the number of debubbling stages and the initial operating parameters for each debubbling stage, including: Detect the initial viscosity of ceramic slurry; The number of defoaming stages and the initial operating parameters of each defoaming stage are determined according to the initial viscosity; wherein the number of defoaming stages is positively correlated with the initial viscosity, and the higher the initial viscosity, the more defoaming stages are divided.

3. The defoaming method of MLCC ceramic slurry according to claim 2, characterized in that: The following steps are also included: At the beginning of each defoaming stage, the real-time viscosity of the ceramic slurry is detected, and the initial operation parameters of the stage are adjusted according to the real-time viscosity.

4. The defoaming method of MLCC ceramic slurry according to claim 2 or 3, characterized in that: The stirring mechanism of the defoaming device includes an electric motor, and the method further includes the following steps: During the operation of each defoaming stage, obtaining the current value of the electric motor in real time; According to the comparison result between the current value and the preset threshold, the duration of the current stage is dynamically adjusted: if the current value continues to exceed the preset upper limit threshold, the duration of the current stage is shortened; if the current value continues to be lower than the preset lower limit threshold, the duration of the current stage is extended.

5. The defoaming method of MLCC ceramic slurry according to claim 4, characterized in that: The following steps are also included: If the rate of change of the current value increasing upward is greater than a preset change threshold, the vacuum degree and / or stirring speed of the current stage is reduced.

6. The method for defoaming MLCC ceramic slurry according to claim 1, characterized in that: The number of the defoaming stages is four, and the execution order is the first pressure state stage, the second pressure state stage, the first pressure state stage, and the second pressure state stage.

7. The method for defoaming MLCC ceramic slurry according to claim 6, characterized in that: The durations of the four stress state stages are 60-100min, 100-120min, 60-100min, and 240min-280min respectively.

8. The method for defoaming MLCC ceramic slurry according to claim 6, characterized in that: The stirring speed is greater than 0 and less than or equal to 20 rpm.

9. The method for defoaming MLCC ceramic slurry according to claim 6, characterized in that: The preset vacuum degree threshold is -95 kPa.

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