Blackening agent and application thereof in preparation of laminated chip inductor

Abstract

The invention discloses a blackening agent and application thereof in preparation of a laminated chip inductor, and relates to the technical field of preparation of electronic components. The present invention provides a blackening agent, which comprises a sulfur-containing compound and a solvent, and the amount-of-substance concentration of the sulfur element in the blackening agent is 0.1-0.5 mol / L. According to the preparation method of the laminated chip inductor, the light reflection problem of metal silver can be completely eliminated by using the blackening agent, instrument change on a light source or an irradiation angle and the like is not needed, the cutting window range of accurate identification of a cutting line can be effectively expanded, the cutting qualification rate and the cutting precision are improved, and the production cost is reduced. And the single laminated chip inductor with good cutting quality is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of electronic component preparation, in particular to a blackening agent and application thereof in the preparation of a laminated chip inductor. Background Art

[0002] Common types of inductors include winding type, integrated type and stacked type. Compared with the other two types, stacked inductors are more suitable for miniaturizing the size of inductors and are easier to achieve large-scale production. Stacked inductors are obtained by stacking printed sheets with specific internal electrode patterns. The multiple layers of internal electrodes form a closed loop in the stacking direction to generate inductance. The entire stacked structure is cut according to specific cutting points to obtain a single inductor green body.

[0003] In the prior art, when screen printing the inner electrode, the cutting lines for guiding cutting are printed around the printed sheet at the same time, and then the grayscale of the CCD camera of the cutting machine is adjusted and the color of the cutting line is identified for precise cutting. The specific grayscale value adjustment method is to adjust the light-colored part to white and the dark-colored part to black to obtain a clear brightness difference between the cutting line and the laminated ceramic body, thereby achieving the purpose of identifying the cutting line. However, since the color difference between the cutting line printed by silver paste and the light-colored ceramic body is small, it is adjusted to a grayscale value range that can be accurately identified by the machine, that is, the ceramic body with a lower grayscale value appears white and the cutting line appears black. However, metallic silver reflects light under the illumination of the light source, and the grayscale value of the reflective part is lower than that of the ceramic body, thus appearing white. The effective recognition window is small, making it difficult to identify the cutting line. The solution to the reflection problem is usually to improve the color of the light source or the irradiation angle, such as changing to blue light or offsetting the incident light. However, the reflection phenomenon under blue light cannot be completely eliminated. When the incident light deviates from a certain angle, a shadow area will be formed at the edge of the cutting line. After adjustment, it will be displayed in black. It is easy to be identified as a cutting line during recognition, resulting in inaccurate recognition, which in turn leads to a decrease in the cutting qualification rate and cutting accuracy. Summary of the invention

[0004] Based on this, the purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a blackening agent that can completely eliminate the reflection problem of metallic silver without changing the light source or illumination angle and other instruments, and can effectively expand the cutting window range, improve the cutting qualification rate and cutting accuracy, and its application in the preparation of multilayer chip inductors.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a blackening agent, comprising a sulfur-containing compound and a solvent, wherein the molar concentration of sulfur in the blackening agent is 0.1-0.5 mol / L.

[0007] The sulfur-containing compound in the blackening agent of the present invention exists as a color developer, and the solvent provides a reaction medium for the oxidation reaction, which produces an efficient color development effect with the cutting line made of silver paste on the laminated ceramic body. The specific mechanism is as follows: Silver will change color due to the combined reaction of oxygen in the air and sulfur ions in the solution, and the reaction will generate Ag2S. The color change reaction can be expressed as: 4Ag+O2+2H2O+2S 2- →2Ag2S+4OH - The color of silver itself will deepen with the increase of oxidation degree. When the oxidation reaction is not complete, it will show light yellow-brown. As the corrosion degree deepens, it will gradually darken and finally turn into black-gray. The oxidized cutting line will not reflect light under the illumination of external light source. The precise position of the cutting line can be accurately identified, which greatly enhances the recognition effect of the cutting machine and greatly improves the cutting qualification rate and cutting accuracy.

[0008] When the molar concentration of sulfur in the blackening agent of the present invention is 0.1-0.5 mol / L, it can quickly develop color. When the concentration is too low, the blackening effect of silver is not obvious, resulting in a long color development time or a light yellow color after color development, which is difficult to effectively identify and is not conducive to improving the cutting pass rate and cutting accuracy. When the concentration is too high, a small amount of H2S may volatilize, which then diffuses inward along the holes in the ceramic layer and corrodes the internal electrode, resulting in poor quality and overall performance of the single multilayer chip inductor, that is, the single multilayer chip inductor after cutting is unqualified.

[0009] Preferably, the molar concentration of sulfur in the blackening agent is 0.3-0.4 mol / L.

[0010] Preferably, the sulfur-containing compound is K2S, Na2S, BaS, (NH4)2S x At least one of , wherein x=2-6.

[0011] Preferably, the blackening agent further comprises a water-soluble ammonium salt.

[0012] Preferably, the ammonium salt is at least one of NH4Cl, (NH4)2SO4, NH4NO3, and (NH4)2CO3.

[0013] Preferably, the molar concentration of ammonium ions in the ammonium salt is 0-1 mol / L.

[0014] More preferably, the ammonium salt is acidic when hydrolyzed.

[0015] Further preferably, the ammonium salt is at least one of NH4Cl, (NH4)2SO4, and NH4NO3.

[0016] In the present invention, the ammonium salt can enhance the color development effect of the sulfur-containing compound, and after hydrolysis, it becomes acidic to promote the positive progress of the color change reaction, and accelerates the oxidation rate of silver to facilitate rapid color development.

[0017] Preferably, the solvent is a solvent that dissolves the sulfur-containing compound and / or the water-soluble ammonium salt. Specifically, the solvent is at least one of water and ethanol.

[0018] In a second aspect, the present invention provides the use of the blackening agent in the preparation of a laminated chip inductor.

[0019] The present invention provides a method for preparing the laminated chip inductor, comprising the following steps:

[0020] S1: After casting, printing, lamination and pressing, a whole laminated ceramic green body is obtained, wherein the whole laminated ceramic green body comprises a trimming line of a blank outer edge and a cutting line made by silver paste printing, and a cutting machine identifies a Mark layer on the ceramic green body and cuts at the position of the trimming line, and the cutting line is exposed after the cutting is completed;

[0021] S2: using the blackening agent to treat the exposed cutting line after cutting in S1, and obtaining the treated cutting line after standing for 1-5 minutes, and removing the excess blackening agent to obtain the treated ceramic body green body;

[0022] S3: placing the cutting line on the ceramic green body processed in S2 under the CCD camera of a cutting machine, adjusting the color scale value of the image so that the ceramic green body appears white and the cutting line appears black, and obtaining a single multilayer chip inductor after precise cutting processing.

[0023] Preferably, in S2, the treatment method is at least one of spraying, coating, and printing, and the coating thickness is ≥ 0.01 μm; and the method of removing excess blackening agent is at least one of solvent washing or cloth wiping.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a blackening agent, which can completely eliminate the reflection problem of metallic silver when applied to the preparation of multilayer chip inductors, and there is no need to make instrumental changes to the light source or illumination angle, etc., and can effectively expand the cutting window range for accurate identification of the cutting line, improve the cutting qualification rate and cutting accuracy, and obtain a single multilayer chip inductor with good cutting quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The flowchart of the cutting and preparation of the green body of the multilayer chip inductor in Example 1 is shown in FIG. 1 , wherein 1 is a single multilayer chip inductor on the whole multilayer ceramic green body, 2 is a cutting line, 3 is a trimming line, and 4 is a Mark layer;

[0026] Figure 2 It is a side view of the ceramic green body in Example 1; wherein, Figure (a) is the ceramic green body that has not been treated with a blackening agent, and Figure (b) is the ceramic green body that has been treated with a blackening agent. DETAILED DESCRIPTION

[0027] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation and comparative examples of the present invention are all commonly used ordinary reagents and instruments, which can be obtained from commercial channels. The experimental methods used in the embodiments and comparative examples are all conventional methods unless otherwise specified; and unless otherwise specified, the raw materials used in parallel experiments are the same batch of raw materials.

[0028] Examples 1-9 and Comparative Examples 1-3

[0029] Example 1

[0030] The present invention provides a method for preparing a laminated chip inductor, comprising the following steps:

[0031] S1: After casting, printing, lamination and pressing, a whole stacked ceramic green body is obtained. The whole stacked ceramic green body includes a trimming line of a blank outer edge and a cutting line made by silver paste printing. The trimming line is used to separate the ceramic green body and the blank outer edge. After the cutting machine identifies the Mark layer on the ceramic green body, it cuts at the trimming line position. After the cutting is completed, the cutting line is exposed. The cutting line is used to identify the cutting position of a single stacked chip inductor;

[0032] S2: Use a blackening agent to treat the exposed cutting line after cutting in S1. The treatment method is spraying with a coating thickness of 0.01μm to ensure that the blackening agent is evenly distributed on the surface and fully contacts and reacts with the silver paste in the cutting line. After standing in the air for 2 minutes, the black cutting line is obtained. After the treatment is completed, the excess blackening agent is removed by wiping with a cloth;

[0033] S3: placing the cutting line on the ceramic green body processed in S2 under the CCD camera of the cutting machine, adjusting the color scale value of the image so that the ceramic green body appears white and the cutting line appears black, and performing precise cutting processing to obtain a single multilayer chip inductor.

[0034] Taking the mass of the blackening agent used in Example 1 as 100 wt %, the specific formula is 3.05 wt % K2S, 92.12 wt % H2O, and 4.83 wt % NH4Cl.

[0035] in, Figure 1 The flowchart of the cutting and preparation of the green body of the multilayer chip inductor in Example 1 is shown in FIG. 1 , wherein 1 is a single multilayer chip inductor on the whole multilayer ceramic green body, 2 is a cutting line, 3 is a trimming line, and 4 is a Mark layer; Figure 2 Figure 2 is a side view of a ceramic green body; wherein Figure (a) is a ceramic green body that has not been treated with a blackening agent, and Figure (b) is a ceramic green body that has been treated with a blackening agent.

[0036] The green cutting and preparation process of the multilayer chip inductor in the other embodiments and comparative examples is similar to that in the first embodiment, and will not be described in detail here.

[0037] In Examples 1-9 and Comparative Examples 1-3, only the blackening agents used are different. The preparation method of the multilayer chip inductor is exactly the same as that of Example 1. The selection of the blackening agent is shown in Table 1.

[0038] Table 1

[0039]

[0040]

[0041] Performance Testing

[0042] Examples 1-9 and Comparative Examples 1-3 were tested for cutting window, cutting qualified rate and green blank qualified rate, respectively. The test methods, standards and requirements are shown in Table 2. The results of the performance test are shown in Table 3.

[0043] Table 2

[0044]

[0045]

[0046] Table 3

[0047] Cutting Window Cutting qualification rate / % Green billet qualification rate / % Example 1 90 100 100 Example 2 89 100 100 Example 3 65 99.8 100 Example 4 87 99.9 99.5 Example 5 79 100 100 Example 6 76 100 100 Example 7 81 100 100 Example 8 70 99.9 99.8 Example 9 64 99.1 99.5 Comparative Example 1 14 96.3 - Comparative Example 2 15 96.5 - Comparative Example 3 91 100 81.7

[0048] It can be seen from the above table that the blackening agent provided by the present invention can be used in the preparation of multilayer chip inductors to completely eliminate the reflection problem of metallic silver, effectively expand the cutting window range for accurate identification of cutting lines, and improve the cutting qualification rate and green billet qualification rate.

[0049] From the comparison of Examples 1-4 and Comparative Examples 2-3, it can be seen that when the molar concentration of sulfur in the blackening agent is 0.1-0.5 mol / L, the color can be developed quickly and well. When the molar concentration of sulfur in the blackening agent is 0.3-0.4 mol / L, the cutting window can be further expanded, and the cutting pass rate and cutting accuracy can be improved. However, when there is no sulfur or the molar concentration of sulfur is too low, the silver blackening effect is not obvious, resulting in a long color development time or a light yellow color after color development, which is difficult to effectively identify, and a small cutting window, which is not conducive to improving the cutting pass rate and cutting accuracy; when the concentration is too high, a small amount of H2S may volatilize, and then diffuse inward along the pores of the ceramic layer, corrode the internal electrode, and reduce the green body pass rate.

[0050] From the comparison between Example 1 and Example 9, it can be seen that adding ammonium salt components to the blackening agent can better improve the cutting window range, cutting qualification rate and green blank qualification rate.

[0051] From the comparison between Example 1 and Examples 5-8, it can be seen that when the ammonium salt in the blackening agent is hydrolyzed to be acidic, a better cutting window range, a higher cutting qualification rate and a green blank qualification rate can be obtained.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A blackening agent, characterized in that: The blackening agent comprises a sulfur-containing compound and a solvent, wherein the molar concentration of sulfur in the blackening agent is 0.1-0.5 mol / L.

2. The blackening agent according to claim 1, characterized in that The molar concentration of sulfur in the blackening agent is 0.3-0.4 mol / L.

3. The blackening agent according to claim 1, characterized in that The sulfur-containing compound is K2S, Na2S, BaS, (NH4)2S x At least one of , wherein x=2-6.

4. The blackening agent according to claim 1, characterized in that It also includes a water-soluble ammonium salt, which is at least one of NH4Cl, (NH4)2SO4, NH4NO3, and (NH4)2CO3.

5. The blackening agent according to claim 4, characterized in that The molar concentration of ammonium ions in the ammonium salt is 0-1 mol / L.

6. The blackening agent according to claim 4, characterized in that The ammonium salt is acidic when hydrolyzed, and the ammonium salt is at least one of NH4Cl, (NH4)2SO4, and NH4NO3.

7. The blackening agent according to claim 4, characterized in that The solvent is a solvent that dissolves the sulfur-containing compound and / or the water-soluble ammonium salt, and the solvent is at least one of water and ethanol.

8. Use of the blackening agent according to any one of claims 1 to 7 in the preparation of a laminated chip inductor.

9. A method for preparing a multilayer chip inductor, characterized in that: The following steps are involved: S1: After casting, printing, lamination and pressing, a whole laminated ceramic green body is obtained, wherein the whole laminated ceramic green body comprises a trimming line of a blank outer edge and a cutting line made by silver paste printing, and a cutting machine identifies a Mark layer on the ceramic green body and cuts at the position of the trimming line, and the cutting line is exposed after the cutting is completed; S2: using the blackening agent described in any one of claims 1 to 7 to treat the cut line exposed after cutting in S1, and obtaining the treated cut line after standing for 1 to 5 minutes, and removing excess blackening agent to obtain the treated ceramic body green body; S3: placing the cutting line on the ceramic green body processed in S2 under the CCD camera of a cutting machine, adjusting the color scale value of the image so that the ceramic green body appears white and the cutting line appears black, and obtaining a single multilayer chip inductor after precise cutting processing.

10. The method for preparing a multilayer chip inductor according to claim 9, wherein: In S2, the treatment method is at least one of spraying, coating, and printing, and the coating thickness is ≥0.01 μm; the method of removing excess blackening agent is at least one of solvent washing or cloth wiping.

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