Method for preparing multilayer chip ceramic capacitor

Abstract

The present invention relates to a method for preparing a multilayer chip ceramic capacitor. The method comprises the following steps: affixing a plurality of sintered ceramic bodies with their end faces facing upward or downward to the inner bottom surface of a glue injection container, injecting adhesive into the glue injection container and covering the upper surface of the ceramic bodies; removing the glue injection container after the adhesive dries to obtain an adhesive block; grinding the upper and lower surfaces of the adhesive block to expose the two end faces of the ceramic bodies, and sputtering external electrode layers on the upper and lower surfaces of the adhesive block after grinding; oxidizing or carbonizing the adhesive block with the sputtered external electrode layers at high temperature to remove adhesive residues and separate a plurality of multilayer chip ceramic capacitors. This solves the problem of the traditional slurry dipping process where the slurry easily sticks to the end-sealing tooling, resulting in slurry dipping failure, and also avoids the curvature of the obtained external electrode surface. The unevenness of the external electrode surface makes bonding difficult for users during welding, and is prone to insufficient bonding force.

Description

Technical Field

[0001] The present invention relates to the field of multilayer chip ceramic capacitors, and in particular to the field of a method for preparing a gold-terminated vertical electrode multilayer chip ceramic capacitor. Background Art

[0002] At present, multilayer ceramic capacitors are prepared through the following processes: slurry batching, casting, printing and stacking, cutting, debonding, sintering, chamfering, capping, burning end, electroplating, etc. When using this process to prepare multilayer chip ceramic capacitors, when capping and dipping, because multilayer chip ceramic capacitors are generally thin, the distance between the slurry surface and the capping tooling is small, and the slurry is easily attached to the capping tooling, resulting in slurry dipping failure. Even if the capping process is successful, the surface tension of the slurry will cause the surface of the outer electrode to produce a curvature (thick in the middle and thin around). The uneven surface of the outer electrode makes it difficult for users to bond gold wire or gold ribbon, and it is easy to have insufficient bonding force. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a method for preparing a multilayer chip ceramic capacitor, which can improve the problems of slurry adhesion failure and uneven outer electrode surface during the current process of capping.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for preparing a multilayer chip ceramic capacitor comprises the following steps:

[0006] Casting the ceramic slurry into a film to obtain a ceramic film;

[0007] Printing metal slurry on the ceramic film to form an internal electrode layer, and drying to obtain a ceramic film printed with an internal electrode pattern;

[0008] The ceramic films printed with internal electrode patterns are alternately stacked, and then stacked with one or more ceramic films that are not printed, and pressed to obtain a laminate;

[0009] Cutting the stacked body in a direction perpendicular to the plane where the ceramic film is located to obtain a plurality of multilayer chip ceramic capacitor green sheets of the same size;

[0010] Debinding and sintering the cut multilayer chip ceramic capacitor green body to obtain a ceramic body;

[0011] affix a plurality of ceramic bodies with their end faces facing upward or downward to the inner bottom surface of a glue injection container, inject adhesive into the glue injection container and cover the upper surface of the ceramic bodies; remove the glue injection container after the adhesive dries to obtain an adhesive block;

[0012] Grinding the upper and lower surfaces of the adhesive block to expose the two end faces of the ceramic body, and sputtering the outer electrode layers on the upper and lower surfaces of the adhesive block after grinding;

[0013] The adhesive block after the sputtering of the outer electrode layer is oxidized or carbonized at high temperature to remove the adhesive residue and separate multiple multilayer chip ceramic capacitors.

[0014] Furthermore, the adhesive is a mixture of one or more of the following:

[0015] Epoxy resin, polyester resin, vinyl resin, polyurethane resin.

[0016] Furthermore, the adhesive drying process includes:

[0017] The glue injection container is dried at a temperature of 50 to 130° C. for 1 to 60 minutes or placed at room temperature for 2 to 48 hours.

[0018] Furthermore, the adhesive block after the sputtering of the outer electrode layer is oxidized or carbonized at high temperature, and the process parameters include:

[0019] The oxidation or carbonization temperature is 250-400° C., and the oxidation or carbonization time is 5-60 minutes.

[0020] Further, grinding the upper and lower surfaces of the adhesive block comprises:

[0021] The upper and lower surfaces of the adhesive block are ground by coarse grinding and fine grinding using sandpaper of different specifications in a grinder to expose both end faces of all the ceramic bodies and make the surfaces smooth, wherein the mesh number of the sandpaper is 100 to 3000 meshes.

[0022] Furthermore, metal paste is printed on the ceramic film to form an internal electrode layer, and the metal paste for printing the internal electrode is nickel metal paste, copper metal paste, or silver-palladium metal paste.

[0023] Furthermore, ceramic films printed with inner electrode patterns are alternately stacked with each other, and then stacked and pressed with one or more unprinted ceramic films to obtain a stack in which the distance between the inner electrodes and the upper and lower surfaces of the stack is greater than 0.02 mm.

[0024] Furthermore, multiple sintered ceramic bodies are placed with their end faces facing upward or downward into a glue injection container, adhesive is injected into the glue injection container and does not cover the upper surface of the ceramic body. After the adhesive dries, the glue injection container is removed to obtain an adhesive block; the internal electrodes of the ceramic body in the adhesive block are perpendicular to the upper and lower surfaces of the adhesive block.

[0025] Furthermore, in the sputtering of the outer electrode layers on the upper and lower surfaces of the adhesive block after grinding, the outermost layer material of the outer electrode layers is gold.

[0026] The present invention provides a method for preparing a multilayer chip ceramic capacitor, which comprises the following steps: placing a plurality of sintered ceramic bodies with their end faces facing upward or downward into a glue injection container, injecting adhesive into the glue injection container and covering the upper surface of the ceramic bodies, and removing the glue injection container after the adhesive dries to obtain an adhesive block; grinding the upper and lower surfaces of the adhesive block to expose the two end faces of the ceramic bodies, and sputtering external electrode layers on the upper and lower surfaces of the adhesive block after grinding; oxidizing or carbonizing the adhesive block with the sputtered external electrode layers at high temperature to remove adhesive residues, and finally separating a plurality of multilayer chip ceramic capacitors; thereby solving the problem of the traditional dipping process in which the slurry easily sticks to the end-sealing tooling, resulting in dipping failure, and also avoiding the problem of the uneven external electrode surface resulting in insufficient bonding force when the user welds.

[0027] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A flowchart of a method for preparing a multilayer chip ceramic capacitor provided in this application;

[0029] Figure 2 This is a schematic structural diagram of a glue injection container provided in this application. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

[0031] It should be clear that the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the embodiments of the present application.

[0032] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present application. The singular forms "a," "the," and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0033] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0034] In addition, in this application, unless otherwise specified, "plurality" refers to two or more. "And / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0036] Regarding the technical issues mentioned in the background technology, refer to Figure 1 The present invention provides a method for preparing a multilayer chip ceramic capacitor, comprising the following steps:

[0037] S1: tape-casting the ceramic slurry to obtain a ceramic film.

[0038] S2: Printing metal slurry on the ceramic film to form an internal electrode layer, and drying to obtain a ceramic film printed with an internal electrode pattern.

[0039] S3: The ceramic films printed with the inner electrode pattern are alternately stacked with each other, and then stacked with one or more ceramic films that are not printed, and pressed together to obtain a laminate.

[0040] The internal electrode pattern is distributed in an array on the ceramic film, with a certain gap between each internal electrode. The width of the gap is slightly larger than the thickness of the cutter, for example, the gap width is 0.1mm to 0.4mm. The metal paste used to print the internal electrodes can be nickel metal paste, copper metal paste, or silver palladium metal paste. The metal paste can be printed on the ceramic film using a screen printing process.

[0041] In the present invention, a ceramic film printed with an inner electrode pattern is used as the inner electrode, and the ceramic film prepared in step S1 is used as the protective layer. The inner electrodes are stacked in an alternating manner according to a predetermined number, and then a predetermined number of protective layers are stacked on the upper and lower sides respectively to protect the inner electrodes. After pressing, a laminate is obtained; preferably, the distance between the inner electrode and the upper and lower surfaces of the laminate is greater than 0.02 mm.

[0042] S4: cutting the laminate along a direction perpendicular to the plane where the ceramic film is located to obtain a plurality of multilayer chip ceramic capacitor green sheets of the same size.

[0043] In the present invention, the internal electrode patterns are arranged equidistantly according to a preset spacing. If the spacing between the side of the internal electrode of the multilayer chip ceramic capacitor green body that should not be exposed after cutting and the edge of the multilayer chip ceramic capacitor green body is too small, the internal electrode may be exposed during the chamfering or grinding process, resulting in a short circuit or a risk of short circuit in the multilayer chip ceramic capacitor. Therefore, an accurate cutting position should be set during the cutting process to prevent the margin of the internal electrode of some multilayer chip ceramic capacitor green bodies from being too small, where the margin is the distance from the electrode to the side of the capacitor.

[0044] S5: Debinding and sintering the cut multilayer chip ceramic capacitor green body to obtain a ceramic body.

[0045] In one embodiment, the sintering process is to heat the debinded multilayer chip ceramic capacitor green body to 900° C. to 1300° C. and hold the temperature for 2 to 4 hours in a reducing gas atmosphere to obtain a ceramic body. The reducing gas atmosphere can be a mixed gas atmosphere of humidified nitrogen and hydrogen, wherein the volume ratio of hydrogen to nitrogen can be 0 to 2:100.

[0046] S6: Paste the end faces of the plurality of ceramic bodies upward or downward on the inner bottom surface of the glue injection container, inject adhesive into the glue injection container and cover the upper surface of the ceramic bodies; remove the glue injection container after the adhesive dries to obtain an adhesive block.

[0047] like Figure 2 As shown, Figure 2 This is a structural diagram of a glue injection container 200 in an embodiment. The bottom surface of the glue injection container 200 is flat, and the inner height is greater than the placement height of the ceramic body. After the adhesive is injected into the glue injection container 200, the adhesive can completely cover the upper surface of the ceramic body 300.

[0048] exist Figure 2In the embodiment, the inner bottom surface of the glue injection container 200 is pre-deposited with a glue 400 for attaching the end surface of the ceramic body 300. This glue can be double-sided tape or other adhesive. After the end surface of the ceramic body 300 is attached to the glue 400, the adhesive is injected into the glue injection container 200 to cover the upper surface of the ceramic body 300.

[0049] An adhesive is an organic or inorganic, natural or synthetic substance that can connect one or more homogeneous or heterogeneous parts (or materials) and has sufficient strength after curing. Preferably, the adhesive used in this application is epoxy resin glue. In other examples, the adhesive can be a mixture of one or more of the following: epoxy resin, polyester resin, vinyl resin, and polyurethane resin.

[0050] Epoxy resin glue is reprocessed or modified on the basis of epoxy resin to make its performance parameters meet specific requirements. Usually, epoxy resin glue also needs to be used with a curing agent, and needs to be mixed evenly before it can be completely cured. Generally, epoxy resin glue is called A glue or main agent, and the curing agent is called B glue or curing agent; the excellent bonding ability of epoxy resin glue is suitable for bonding the ceramic body in this application to ensure that the ceramic body does not loosen when the cured adhesive block is ground, and due to its transparency, it is easy to observe the grinding effect.

[0051] In a preferred embodiment, the adhesive drying process includes:

[0052] The injection container is dried at a temperature of 50 to 130° C. for 1 to 60 minutes or placed at room temperature for 2 to 48 hours.

[0053] S7: grinding the upper and lower surfaces of the adhesive block to expose the two end faces of the ceramic body, and sputtering external electrode layers on the upper and lower surfaces of the adhesive block after grinding;

[0054] Optionally, sandpaper of different specifications is used in a grinder to grind the upper and lower surfaces of the adhesive block by coarse grinding and fine grinding to expose both end faces of all the ceramic bodies and make the surfaces smooth, wherein the mesh number of the sandpaper is 100 to 3000.

[0055] In the present invention, the external electrode layers are sputtered on the upper and lower surfaces of the polished adhesive block by sputtering. In this application, the external electrodes with uniform thickness and flatness can be obtained by sputtering the external electrode layers on the upper and lower surfaces.

[0056] Preferably, the material of the outermost layer of the outer electrode layer is gold.

[0057] S8: Oxidizing or carbonizing the adhesive block after the sputtering of the outer electrode layer at high temperature to remove the adhesive residue and separate the multiple multilayer chip ceramic capacitors.

[0058] After the sputtering of the outer electrode layer is completed, in order to separate the multilayer chip ceramic capacitor from the adhesive block, it is necessary to use high temperature to change the internal structure or composition of the adhesive, reduce or lose the bonding force, and thus achieve the effect of removing the adhesive. In a preferred embodiment, the oxidation or carbonization temperature is controlled between 250 and 400°C, and the oxidation or carbonization time is controlled between 5 and 60 minutes.

[0059] In a specific embodiment, the method for preparing a multilayer chip ceramic capacitor of the present invention comprises the following steps:

[0060] S11: Ceramic powder doped with a sintering aid, a binder, an organic solvent, a plasticizer, etc. are mixed in a certain proportion and ball-milled to form a stable ceramic slurry with good fluidity. The ceramic slurry is tape-cast to form a ceramic film of a green tape.

[0061] S12: Print nickel metal slurry on the ceramic film prepared in step S11 to form an internal electrode layer, and after drying, obtain a ceramic film printed with an internal electrode pattern. The ceramic films printed with the internal electrode pattern are stacked one on another in an alternating manner, and then stacked with one or more ceramic films prepared in step S11, and pressed to obtain a laminate.

[0062] S13: Cut the laminate into multiple equal-sized multilayer chip ceramic capacitor green sheets along a direction perpendicular to the plane where the ceramic film is located. The cut multilayer chip ceramic capacitor green sheets are then debonded and heated to 900°C to 1300°C in a reducing gas atmosphere and kept warm for 2h to 4h for sintering. After sintering, a ceramic body is obtained. The reducing gas atmosphere is a mixed gas atmosphere of humidified nitrogen and hydrogen, wherein the volume ratio of hydrogen to nitrogen is 0 to 2:100.

[0063] S14: Paste multiple ceramic body end faces (two faces perpendicular to the inner electrode and exposed by the inner electrode) upward or downward on the bottom surface of the glue injection container, inject epoxy resin glue into the glue injection container and cover the upper surface of the ceramic body; after the epoxy resin glue is dried, remove the glue injection container to obtain an epoxy resin block; the epoxy resin glue drying process is a drying process at a temperature of 50 to 130°C for 1 to 30 minutes.

[0064] S15: The upper and lower surfaces of the epoxy resin block are coarsely and finely ground using sandpaper of different specifications under a grinder to expose the two end faces of all the ceramic bodies and make the surface flat. The outer electrode layer is sputtered on the upper and lower surfaces of the epoxy resin block after grinding; the mesh number of the sandpaper is 100 to 3000 mesh, and the outermost layer material of the outer electrode layer is gold.

[0065] S16: Carbonizing the epoxy resin block at a high temperature of 250-400° C. for 5-60 minutes. Residual epoxy resin is then removed to separate the plurality of multilayer chip ceramic capacitors.

[0066] The present invention discloses a method for preparing a multilayer chip ceramic capacitor, which comprises the following steps: attaching the end faces of multiple sintered ceramic bodies to the bottom surface of a glue injection container with the end faces facing upward or downward, injecting adhesive into the glue injection container and covering the upper surface of the ceramic body; removing the glue injection container after the adhesive dries to obtain an adhesive block; grinding the upper and lower surfaces of the adhesive block to expose the two end faces of the ceramic body, and sputtering the outer electrode layer on the upper and lower surfaces of the adhesive block after grinding; oxidizing or carbonizing the adhesive block with the sputtered outer electrode layer at high temperature to remove the adhesive residue and separate multiple multilayer chip ceramic capacitors. This solves the problem of the traditional dipping process where the slurry easily sticks to the end-sealing tooling, resulting in dipping failure, and also avoids the curvature of the outer electrode surface (thick in the middle and thin around the edges). The unevenness of the outer electrode surface makes bonding difficult for the user when welding gold wire or gold ribbon, and is prone to insufficient bonding force.

[0067] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A method for preparing a multilayer chip ceramic capacitor, characterized in that: The following steps are involved: Casting the ceramic slurry into a film to obtain a ceramic film; Printing metal slurry on the ceramic film to form an internal electrode layer, and drying to obtain a ceramic film printed with an internal electrode pattern; The ceramic films printed with internal electrode patterns are alternately stacked, and then stacked with one or more ceramic films that are not printed, and pressed to obtain a laminate; Cutting the stacked body in a direction perpendicular to the plane where the ceramic film is located to obtain a plurality of multilayer chip ceramic capacitor green sheets of the same size; Debinding and sintering the cut multilayer chip ceramic capacitor green body to obtain a ceramic body; affixing a plurality of ceramic bodies with their end faces facing upward or downward to the inner bottom surface of a glue injection container, injecting adhesive into the glue injection container so as not to cover the upper surfaces of the ceramic bodies; removing the glue injection container after the adhesive dries to obtain an adhesive block, wherein the internal electrodes of the ceramic bodies in the adhesive block are perpendicular to the upper and lower surfaces of the adhesive block; Grinding the upper and lower surfaces of the adhesive block to expose the two end faces of the ceramic body, and sputtering the outer electrode layers on the upper and lower surfaces of the adhesive block after grinding; The adhesive block after the sputtering of the outer electrode layer is oxidized or carbonized at high temperature to remove the adhesive residue and separate multiple multilayer chip ceramic capacitors.

2. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: The adhesive is a mixture of one or more of the following: Epoxy resin, polyester resin, vinyl resin, polyurethane resin.

3. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: The adhesive drying process includes: The glue injection container is dried at a temperature of 50 to 130° C. for 1 to 60 minutes or placed at room temperature for 2 to 48 hours.

4. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: The adhesive block after sputtering the outer electrode layer is oxidized or carbonized at high temperature. The process parameters include: The oxidation or carbonization temperature is 250-400° C., and the oxidation or carbonization time is 5-60 minutes.

5. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: Grinding the upper and lower surfaces of the adhesive block, comprising: The upper and lower surfaces of the adhesive block are ground by coarse grinding and fine grinding using sandpaper of different specifications in a grinder to expose both end faces of all the ceramic bodies and make the surfaces flat, wherein the mesh number of the sandpaper is 100-3000 mesh.

6. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: The metal paste for printing the inner electrode is nickel metal paste, copper metal paste or silver palladium metal paste.

7. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: The distances between the inner electrode and the upper and lower surfaces of the stack are both greater than 0.02 mm.

8. The method for preparing a multilayer chip ceramic capacitor according to claim 1, wherein: In the sputtering of external electrode layers on the upper and lower surfaces of the adhesive block after grinding, the outermost layer material of the external electrode layer is gold.

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