JP2005026403A - Process for forming external electrode of chip electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that electrode paste adheres excessively to the end part of a component body and the film thickness of an external electrode becomes uneven when steps for immersing the end part of the component body into an electrode paste layer, and for pulling up the component body from the paste layer are performed in order to form the external electrode at the end part of a chip electronic component body. <P>SOLUTION: Electrode paste 7 containing ferromagnetic material powder is employed, and when the end part of a component body 1 is immersed into a paste layer 8 and then the component body 1 is pulled up from the paste layer 8, magnetic lines of force 11 are generated by a magnetic lines of force generator 6. Excessive electrode paste 7 adhering to the end part of the component body 1 is pulled down by the magnetic force. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４９】
表１からわかるように、実施例によれば、コーナー部における厚みｂを所定以上に確保しながら、側面の最厚部における厚みｃがそれほど厚くならず、端面中央部における厚みａを薄くすることができ、外部電極の膜厚の均一化かつ薄膜化を図ることができる。
【００５０】
これに対して、比較例１および２では、いずれも電極用ペーストの余剰分が除去されないので、側面の最厚部における厚みｃだけでなく、端面中央部における厚みａが、実施例に比べて２倍近くとなり、また、端面中央部における厚みａとコーナー部における厚みｂとの差が大きくなっている。
【００５１】
【発明の効果】
以上のように、この発明によれば、チップ型電子部品の外部電極を形成するにあたって、外部電極のための電極用ペーストとして、強磁性材料粉末を含有するものを用い、この電極用ペーストからなるペースト層を定盤上に形成し、チップ型電子部品のための部品本体の端部をペースト層内に浸漬し、次いで、部品本体をペースト層から引き上げるに際して、定盤に備える磁力線を発生させる手段によって、電極用ペーストの余剰分を引き落とすことができるので、部品本体の端部に付着した電極用ペーストの膜厚の均一化および薄膜化を図ることができ、その結果、外部電極の膜厚の均一化および薄膜化を図ることができる。
【００５２】
したがって、チップ型電子部品を回路基板へ実装する際、半田の濡れ張力によりチップ型電子部品が立つといった不具合が生じにくくなり、また、チップ型電子部品の外形寸法が外部電極の厚みによって規格範囲から外れるといった不具合が生じにくくなる。
【００５３】
この発明において、定盤に備える磁力線発生手段がコイルを備え、部品本体をペースト層から引き上げる工程においてのみ、コイルに電流を流し、磁力線を発生させるようにすれば、電極用ペースト中において強磁性材料粉末の分離が起こるという不都合を回避することができる。
【図面の簡単な説明】
【図１】この発明の一実施形態によるチップ型電子部品の外部電極形成方法に備える典型的な工程を順次示す正面図である。
【図２】この発明による効果を確認するために実施した実験例において採用された外部電極２３の厚みを測定する方法を説明するための図である。
【符号の説明】
１，２１ 部品本体
２，３ 端部
５ 定盤
６ 磁力線発生装置
７ 電極用ペースト
８ ペースト層
１１ 磁力線
２３ 外部電極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming an external electrode of a chip-type electronic component, and more particularly to an improvement for achieving a more uniform film thickness of an external electrode formed by an electrode paste.
[0002]
[Prior art]
For example, an external electrode of a chip-type electronic component such as a multilayer ceramic capacitor is usually formed by the following method.
[0003]
First, a component body for a chip-type electronic component is prepared. When the chip-type electronic component is a multilayer ceramic capacitor, the component body includes a multilayer body including a plurality of laminated ceramic layers and internal electrodes formed along a specific interface between the ceramic layers.
[0004]
On the other hand, an electrode paste for external electrodes is prepared. The electrode paste is obtained by dispersing conductive metal powder and glass frit in an organic vehicle composed of an organic binder and an organic solvent.
[0005]
Next, a paste layer made of an electrode paste is formed on the surface plate.
[0006]
Next, the end of the component main body is immersed in the paste layer, and then the component main body is pulled up from the paste layer, and then the electrode paste attached to the end of the component main body is dried.
[0007]
Next, the electrode paste is fired. As a result of this firing, the electrode paste is sintered, and an external electrode is formed with this sintered body. When the chip-type electronic component is a multilayer ceramic capacitor, the external electrode is electrically connected to a specific one of the internal electrodes formed inside the component main body.
[0008]
In some cases, a heat-curing type paste is used as the electrode paste. In this case, the firing step is not performed, and the electrode paste is heat-cured in the previous drying step, whereby the external electrode. Is formed.
[0009]
However, when the external electrode forming method as described above is adopted, there is a tendency that the electrode paste adheres in an excessive amount on the end face of the component body, and due to this, the formed external electrode is A convex shape is formed on the end surface of the component body, and the difference in film thickness between the corners of the end surface increases, resulting in a problem that the film thickness of the external electrode is not uniform as a whole, or on the end surface of the external electrode. There may be a problem that a cavity is formed in a portion located in the area.
[0010]
As described above, when the film thickness of the external electrode becomes non-uniform and a convex shape is given on the end surface of the component main body, for example, when mounting a chip-type electronic component on a circuit board, the chip is caused by the wetting tension of solder. In some cases, the mold electronic component may stand up undesirably. In addition, when the thickness of the external electrode on the end face of the component body is larger than necessary, there may be a problem that the external dimensions of the chip-type electronic component are out of the standard range.
[0011]
As a method for solving these problems, after the component body is pulled up from the paste layer, it is transferred and removed onto a flat plate or mesh member in order to remove the excess electrode paste adhered to the end of the component body. (For example, see Patent Document 1).
[0012]
[Patent Document 1]
JP-A-3-248410 [0013]
[Problems to be solved by the invention]
However, in the method described in Patent Document 1 described above, after the end of the component main body is dipped in the paste, and then the component main body is lifted from the paste layer, the excess electrode paste adhered to the end of the component main body A step must be added to remove the minute by transferring it to a flat or mesh member. As a result, the number of processes increases accordingly, and there is a problem that productivity for forming the external electrode is lowered.
[0014]
Further, in order to remove the surplus portion of the electrode paste, a flat plate or a mesh-like member must be prepared, and when considering the reuse of the flat plate or the mesh-like member to which the electrode paste has been transferred, Alternatively, a process for cleaning the mesh-like member is required, and in any case, the manufacturing cost of the chip-type electronic component is increased.
[0015]
Accordingly, an object of the present invention is to provide a method for forming an external electrode of a chip-type electronic component that can solve the above-described problems.
[0016]
[Means for Solving the Problems]
The present invention includes a step of preparing a component body for a chip-type electronic component, a step of forming a paste layer made of an electrode paste on a surface plate, and a step of immersing an end of the component body in the paste layer. Then, the method is directed to a method for forming an external electrode of a chip-type electronic component, comprising: a step of pulling up the component main body from the paste layer; and a step of drying the electrode paste attached to the end of the component main body. In order to solve the above technical problem, the present invention is characterized by having the following configuration.
[0017]
That is, a paste containing a ferromagnetic material is used as the electrode paste. And as a surface plate, what is provided with the means to generate a magnetic force line in the paste layer formed on it is used.
[0018]
According to the external electrode forming method of the chip-type electronic component having such a configuration, the surplus portion of the electrode paste attached to the end of the component main body is pulled down to the surface plate side by the magnetic force, so the film thickness of the electrode paste As a result, the film thickness of the external electrode can be made more uniform.
[0019]
In the present invention, it is preferable that the means for generating the magnetic lines of force provided on the surface plate includes a coil, and only in the step of pulling up the component main body from the paste layer, an electric current is passed through the coil to generate the magnetic lines of force.
[0020]
When the electrode paste contains, for example, glass frit and the external electrode is formed from a sintered body of electrode paste, the electrode paste is used after the step of drying the electrode paste described above. A step of baking the paste is further performed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view for explaining a method for forming an external electrode of a chip-type electronic component according to an embodiment of the present invention. FIG. 1 sequentially shows typical steps for preparing the external electrode forming method.
[0022]
With reference to FIG. 1A, a plurality of component bodies 1 for a chip-type electronic component are prepared. These component main bodies 1 are in a state of being held by the holder 4 on the other end 3 side with one end 2 facing downward.
[0023]
A surface plate 5 having a flat upper surface is disposed below the holder 4. The surface plate 5 incorporates, for example, a magnetic field generator 6 including a coil.
[0024]
A paste layer 8 made of electrode paste 7 is formed on the surface plate 5. The paste layer 8 has a predetermined thickness. In order to form such a paste layer 8, for example, electrode paste 7 is supplied onto the surface plate 5, and then a scraping blade (not shown) is placed at a predetermined distance from the upper surface of the surface plate 5. It moves along this upper surface in the state which separated.
[0025]
The electrode paste 7 is, for example, a conductive metal powder and glass frit dispersed in an organic vehicle composed of an organic binder and an organic solvent. In this invention, the electrode paste 7 contains a ferromagnetic material powder. It is characterized by.
[0026]
In this case, the conductive metal powder itself as a conductive component for imparting conductivity to the electrode paste may be provided from a ferromagnetic material powder such as nickel powder or iron powder, or may be conductive. As the metal powder, two or more types such as copper powder and iron powder are used, and the ferromagnetic material powder may be provided by, for example, iron powder as a part thereof. Furthermore, the ferromagnetic material powder does not become a conductive component in the electrode paste, and may be provided by a nonconductive material.
[0027]
Further, the content of the ferromagnetic material powder in the electrode paste 7 depends on the magnetic properties of the ferromagnetic material and the capability of the magnetic force line generator 6, but depending on the magnetic lines of force from the magnetic force line generator 6, It is chosen so that the behavior can be influenced.
[0028]
Next, as shown in FIG. 1 (2), the holder 4 is moved downward as indicated by an arrow 9. As a result, one end 2 of the component body 1 is immersed in the paste layer 8. At this time, the component main body 1 may or may not come into contact with the end plate 2 side end surface.
[0029]
Next, as shown in FIG. 1 (3), the holder 4 is moved upward as indicated by an arrow 10. Thereby, the component main body 1 is pulled up from the paste layer 8. The electrode paste 7 is attached to the end 2 of the component body 1 pulled up in this way.
[0030]
The step of pulling up the component body 1 shown in FIG. 1 (3) from the paste layer 8, preferably immediately before the pulling is started, a current is passed through the coil provided in the magnetic field generator 6 thereby generating the magnetic field lines 11. Is done. Due to the lines of magnetic force 11, the surplus portion of the electrode paste 7 attached when the component body 1 is pulled up is pulled down to the surface plate 5 side. As a result, in the electrode paste 7 attached on the end 2 of the component body 1, the film thickness is made uniform and the electrode paste 7 is made thinner.
[0031]
Next, the electrode paste 7 attached to the end 2 of the component body 1 is dried.
[0032]
Next, the component main body 1 is held by the holder 4 with the end 3 on the side where the electrode paste 7 is not attached facing downward, and the above-described steps are repeated, and the electrode 3 is also formed on the end 3. The paste for electrode 7 is attached, and then the electrode paste 7 is dried.
[0033]
Next, the electrode paste 7 attached to the end portions 2 and 3 of the component body 1 is baked, whereby external electrodes made of a sintered body of the electrode paste 7 are placed on both end portions 2 and 3 of the component body 1. A formed chip-type electronic component is obtained.
[0034]
While the present invention has been described with reference to the illustrated embodiment, various other modifications are possible within the scope of the present invention.
[0035]
For example, as the electrode paste 7, a thermosetting type may be used. In this case, if the electrode paste 7 is heated in the step of drying the electrode paste 7, the electrode paste 7 is cured, so that it is not necessary to carry out a baking step thereafter.
[0036]
Further, in the above-described embodiment, as shown in FIG. 1 (3), only in the step of pulling up the component body 1 from the paste layer 8, a current is passed through the coil provided in the magnetic field generator 6 to generate the magnetic field lines 11. However, in the magnetic force line generator 6, the magnetic force lines 11 may be generated from the stage shown in FIG. 1 (1), for example, by using a permanent magnet or allowing a current to constantly flow through the coil.
[0037]
As described above, when the magnetic lines of force 11 are always generated, the ferromagnetic material powder may be separated in the electrode paste 7 depending on the viscosity of the electrode paste, the magnetic field intensity by the magnetic lines 11, and the like. There is sex. Therefore, in order to avoid such an inconvenience, it is preferable to generate the magnetic force lines 11 only in the step of pulling up the component body 1 from the paste layer 8 as in the illustrated embodiment.
[0038]
The chip-type electronic component to which the present invention is applied is not limited to a multilayer ceramic capacitor, and any chip can be used as long as an external electrode is formed using an electrode paste at the end of a chip-shaped component body. It can also be applied to chip-type electronic components.
[0039]
Next, experimental examples carried out to confirm the effects of the present invention will be described.
[0040]
First, a component body for a multilayer ceramic capacitor having a length of 3.2 mm, a width of 1.6 mm, and a thickness of 1.0 mm was prepared as a component body for a chip-type electronic component.
[0041]
On the other hand, the electrode paste is composed of 60% by weight of copper powder, 10% by weight of iron powder as ferromagnetic material powder, 5% by weight of glass frit and 25% by weight of organic vehicle, that is, an electrode containing ferromagnetic material In addition to the above-mentioned paste for ferromagnetic material-containing electrodes, the iron powder was replaced with copper powder, and a conductive metal powder containing only copper powder, ie, a ferromagnetic material-free electrode paste was prepared. . As shown in Table 1, in Example and Comparative Example 2, a ferromagnetic material-containing electrode paste was used, and in Comparative Example 1, a ferromagnetic material-free electrode paste was used.
[0042]
Next, the electrode paste was supplied onto a surface plate in which a magnetic field generator having a coil was incorporated, and a paste layer having a thickness of 0.5 mm was formed by a scraping blade.
[0043]
Next, the edge part of the component main body prepared previously was immersed in the paste layer until it contacted the surface plate, and then the component main body was pulled up from the paste layer. In this pulling process, as shown in Table 1, in Example 1 and Comparative Example 1, current was passed through the coil to generate magnetic lines of force, and in Comparative Example 2, the coil was not energized and magnetic lines of force were not generated. .
[0044]
Next, after drying and solidifying the electrode paste attached to the end of the component main body, the component main body is put in an electric furnace and heat-treated at a temperature of 850 ° C. for 10 minutes, and the external electrode made of the electrode paste is attached. Formed at the end of the component body.
[0045]
The thickness of the external electrode was measured for the samples according to each of the Examples and Comparative Examples 1 and 2 thus obtained. Details of this measurement method are shown in FIG.
[0046]
With reference to FIG. 2, polishing was performed on the component main body 21 in parallel with the length direction and the width direction, and this polishing was performed until half of the dimension in the thickness direction of the component main body 21 was reached. In FIG. 2, a specific internal electrode 22 is shown by a broken line. Next, the end face of the external electrode 23 that appears by polishing is observed, the thickness a of the external electrode 23 at the center of the end face 24 of the component main body 21, the thickness b of the external electrode 23 at the corner 25 of the component main body 21, and the component The thickness c of the thickest part of the external electrode 23 on the side surface 26 of the main body 21 was measured. In addition, about the thickness b in the corner part 25, as shown in FIG.
[0047]
As described above, the thickness a at the center of the end face 24, the thickness b at the corner 25, and the thickness c at the thickest part of the side surface 26 of the external electrode 23 are measured for 100 samples, respectively. The value was determined. The results are shown in the columns of “end face central part a”, “corner part b”, and “side surface thickest part c” in Table 1.
[0048]
[Table 1]

[0049]
As can be seen from Table 1, according to the embodiment, the thickness c at the thickest part of the side surface is not so thick and the thickness a at the center part of the end face is reduced while securing the thickness b at the corner part to a predetermined value or more. The thickness of the external electrode can be made uniform and the film thickness can be reduced.
[0050]
On the other hand, in Comparative Examples 1 and 2, since the surplus portion of the electrode paste is not removed, not only the thickness c in the thickest portion of the side surface but also the thickness a in the center portion of the end surface is compared with the embodiment. In addition, the difference between the thickness a at the center portion of the end face and the thickness b at the corner portion is large.
[0051]
【The invention's effect】
As described above, according to the present invention, when forming an external electrode of a chip-type electronic component, the electrode paste for the external electrode is a paste containing a ferromagnetic material powder, and this electrode paste is used. Forming a paste layer on the surface plate, immersing the end of the component body for the chip-type electronic component in the paste layer, and then generating magnetic lines of force for the surface plate when the component body is pulled up from the paste layer Therefore, the excess of the electrode paste can be pulled down, so that the film thickness of the electrode paste adhered to the end of the component body can be made uniform and thinned. Uniformity and thinning can be achieved.
[0052]
Therefore, when mounting the chip-type electronic component on the circuit board, it is difficult to cause a problem that the chip-type electronic component stands due to the wetting tension of the solder. Problems such as detachment are less likely to occur.
[0053]
In this invention, the magnetic force line generating means provided on the surface plate includes a coil, and only in the step of pulling up the component main body from the paste layer, if a current is passed through the coil to generate a magnetic line of force, the ferromagnetic material in the electrode paste The disadvantage of powder separation can be avoided.
[Brief description of the drawings]
FIG. 1 is a front view sequentially illustrating typical steps for preparing a method for forming an external electrode of a chip-type electronic component according to an embodiment of the present invention.
FIG. 2 is a diagram for explaining a method of measuring the thickness of an external electrode 23 employed in an experimental example carried out to confirm the effect of the present invention.
[Explanation of symbols]
1, 21 Parts body 2, 3 Edge 5 Surface plate 6 Magnetic field generator 7 Electrode paste 8 Paste layer 11 Magnetic field line 23 External electrode

Claims (3)

Preparing a component body for a chip-type electronic component;
Forming a paste layer made of electrode paste on a surface plate;
Immersing the end of the component body in the paste layer;
Next, a step of pulling up the component body from the paste layer;
Next, the step of drying the electrode paste attached to the end of the component body,
The electrode paste contains a ferromagnetic material powder,
As the surface plate, one provided with means for generating lines of magnetic force in the paste layer formed thereon is used.
External electrode forming method for chip-type electronic component. 2. The external electrode formation of a chip-type electronic component according to claim 1, wherein the means for generating the magnetic field lines includes a coil, and current is supplied to the coil to generate the magnetic field lines only in the step of pulling up the component body from the paste layer. Method. The method for forming an external electrode of a chip-type electronic component according to claim 1, further comprising a step of firing the electrode paste after the step of drying the electrode paste.

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