JP2512745B2 - External Electrode Forming Method for Chip Electronic Components - Google Patents

Description

The present invention relates to a method for forming external electrodes in a chip electronic component such as a chip capacitor, a chip resistor, and a chip coil.

[Conventional technology]

As an example of a chip electronic component formed by encapsulating an element in ceramics, a laminated ceramic capacitor using ceramics as a dielectric (hereinafter referred to as a chip capacitor)
There is. Such a chip capacitor was developed in order to obtain a small-capacity and large-capacity capacitor.
It has the appearance shown in the figure. That is, the chip capacitor 1 is externally composed of a main body 2 and external electrodes 3 formed on both ends of the main body 2, and the main body 2 has an internal dielectric 4 as shown in FIG. In addition, the internal electrodes 5 connected to the external electrodes 3 are arranged in a comb shape, and the dielectric 4 is filled between the adjacent internal electrodes 5. This type of chip capacitor is very small in size and is generally mounted by soldering the external electrodes 3 directly to the circuit board.

Conventionally, the chip capacitor 1 having the above structure is manufactured as follows.

First, a ceramic dielectric powder, a resin such as acrylic or polyvinyl butyral, and a solvent such as water or trichloroethane are mixed to form a slurry, and the slurry is formed on a film such as polyester or a metal belt of 20 to 100 μm.
It is coated to a thickness of m and dried to form a so-called green sheet. Then, an internal electrode paste containing palladium or the like is printed on this green sheet, these green sheets are laminated so that the internal electrodes 5 which are opposed to each other are alternately formed, and a pressure of 0.1 to 3.0 t / cm ² is applied by pressing. After crimping, the chips are cut, baked and baked (1300 ° C.) to obtain the chip-shaped main body 2.

Then, as shown in FIG. 4, a number of main bodies 2 are aligned and attached to a supporting plate 10 made of metal or resin, and a bath 16 of an external electrode paste 15 made of highly viscous silver paste or palladium paste is placed in the bath 16. Then, the end portions of the respective main bodies 2 held by the support plate 10 are dated, dried and baked (80
Then, the metal glaze conductor 6 is formed. The support plate 10 is formed by fixing a gas plate 12 having a large number of mounting holes 11 to a base 14 via a double-sided adhesive tape 13, and the chip-shaped main body 2 inserted in the mounting holes 11 has both sides. Since it is designed to be temporarily fixed to the adhesive tape 13, if one end of the external electrode paste 15 is applied with a dry coating and dried, the main body 2 is turned over and held on the support plate 10, and the similar coating is applied. , And is then dried to form metal glaze conductors 6 at both ends of the main body 2. Finally, by forming the nickel plating layer 7 on the surface of the metal glaze conductor 6 and further forming the solder plating layer 8 on the surface of the nickel plating layer 7, the external electrodes 3 are provided at both ends of the main body 2. The chip capacitor 1 is completed.

Among the constituent elements of the external electrode 3, the nickel plating layer 7 formed on the surface of the metal glaze conductor 6 is for preventing silver bleeding. The layer 8 is for improving solderability, that is, solder wettability.

[Problems to be solved by the invention]

By the way, the conventional method of forming an external electrode in a chip electronic component such as a chip capacitor is to insert the end portion of the main body 2 into the external electrode paste 15 in the bath 16 as described above. Although squeegeeing is performed along the paste, there is a problem in that the thickness accuracy of the external electrode 3 is poor and the dimensional accuracy of the chip electronic component is difficult to improve because the coating amount varies depending on the type of squeezing. Atsuta In addition, since it is necessary to use a highly viscous external electrode paste 15 in the bath 16 in order to secure a certain amount of application, it is easy for air bubbles to be entrained during the squeegeeing, and these air bubbles will enter the metal glaze conductor 6. As a result of forming the pinhole, the plating solution such as nickel or solder enters the pinhole,
This has been a factor causing poor quality of the chip capacitor 1 as a finished product.

The present invention has been made in view of the above problems of the prior art, the object is to improve the dimensional accuracy, and there is no risk of quality defects due to the inclusion of bubbles,
Another object of the present invention is to provide a method for forming an external electrode of a chip electronic component.

[Means for solving problems]

In order to achieve the above object, the present invention provides a method for forming an external electrode of a chip electronic component, which is manufactured by forming an external electrode electrically connected to the electronic element outside a main body containing the electronic element. After applying a mold release agent into the recesses of a mold having a large number of recesses having an inner mold size substantially equal to the outer dimensions of the mold, each paste is filled with a low-viscosity paste material containing conductive particles. After that, insert a predetermined amount of each of the plurality of main bodies held by the support into the recesses,
The feature is that the paste material is dried in this state to adhere to the main body, and then the mold is released and the paste material is baked.

[Action]

That is, as described above, the external electrode forming method of filling the paste material in the recess of the mold body, drying, releasing, and firing can apply the paste material to the body of the chip electronic component with high thickness accuracy. As a result, the dimensional accuracy of the chip electronic component can be improved, and since the paste material is not a deep coating, a paste material having a low viscosity can be used. Therefore, there is no risk of entraining air bubbles and pinhole generation is avoided. It

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

This embodiment shows a method of forming external electrodes of a chip capacitor. First, as shown in FIG. 1 (a), each through hole of a support plate 21 such as a silicon rubber having a large number of through holes 20 is formed.
The main bodies 2 of the chip capacitors, which are aligned by sieving, are mounted in 20 and one end of each main body 2 is projected from the support plate 21 by a predetermined amount. As described above, the main body 2 is formed by stacking the green sheets printed with the internal electrode paste, press-bonding them, cutting them into chips, and then firing and the like.

On the other hand, before and after the above steps, as shown in FIG. 1B, each recess 22 of the mold body 23 such as a metal having a large number of recesses 22 is formed.
A release agent is applied to the inside of the conductive particles (silver,
After filling the recesses 22 with a paste material 24 in which a palladium frit or the like), a glass frit, a solvent and the like are mixed at a predetermined ratio, squeezing is performed using a squeeze member 25. Here, the internal dimension of each recess 22 is set to be substantially the same as the external dimension of the external electrode of the chip capacitor, more accurately, the external dimension of the metal glaze conductor of the external electrode.
The paste material 24 filled in 22 has a lower viscosity than the conventional external electrode.

Then, on the surface of the mold body 23 in which the paste material 24 is filled in the recess 22 on the side where the recess 22 is formed, the main body 2 of the support 21 is formed.
After the surfaces on the protruding side are opposed to each other and the main body 2 is set on each of the recesses 22 by the positioning means (not shown), one end portion of the main body 2, that is, the support, is supported as shown in FIG. 1 (c). A predetermined amount of the end projecting from the plate 21 is inserted into the recess 22.

Then, after the end portion of the main body 2 is inserted into the recess 22 and dried, the paste material 24 is applied to the end portion, and then the mold is released, as shown in FIG. A cap-shaped paste 24 'is formed on each of the two integrated portions. In addition,
Since the mold release agent is applied in advance in the recess 22, the paste material 24 is surely applied to the main body 2 when the paste material 24 dries and the solvent evaporates.

When the cap-shaped paste 24 'is formed on one end of the main body 2 in this manner, the end projecting from the support plate 21 is pushed in to project the other end, and the other steps are repeated by repeating the above steps. The same cap paste 24 '
To form. After that, the cap-shaped paste 24 'formed on both ends of the main body 2 is fired at 800 to 900 ° C, and the resin and the plasticizer contained in the cap-shaped paste 24' are burned by this firing process. As the glass frit is melted and removed, each cap-shaped paste 24 'becomes a metal glaze conductor adhered to the surface of the main body 2 with high adhesion strength.

Finally, a nickel plating layer is formed on the surface of this metal glaze conductor, and a solder plating layer is further formed on the surface of this nickel plating layer, thereby completing the external electrode of the chip capacitor.

The external electrode formed in the above step has a predetermined size of the cup-shaped paste 24 'by setting the recess 22 of the mold body 23 to an appropriate size, that is, a size in consideration of reduction of the paste material 24 due to drying. Since it can be formed into a predetermined shape and has a predetermined thickness, it is superior in thickness accuracy to a conventional external electrode formed by dip coating. Therefore, the dimensional accuracy of the chip capacitor is high.

Further, in the conventional method by the deep coating, since it is necessary to increase the viscosity of the external electrode paste, entrapment of bubbles at the time of squeezing was a problem, but in this embodiment, the paste material 24 is placed in the recess 22. Since it is dried and adhered to the main body 2, a relatively low-viscosity material can be used, so there is no risk of air bubbles being entrained during squeegeeing, pinholes are prevented from occurring due to air bubble mixing, and quality is stable. Chip capacitors are now available.

Further, in the case of the conventional method in which the main body 2 is held by using the double-sided adhesive tape, the work of reversing a large number of main bodies 2 after the one end of the main body 2 is dry coated and dried is complicated. As described above, when the main body 2 is held by using the support plate 21 such as silicon rubber having a large number of through holes 20,
After forming the cap-shaped paste 24 'at one end, the main body 2
The other end can be projected from the support plate 21 by pushing in, and it is not necessary to invert the main body 2, so that workability is good.

Although the above embodiments have described only the case of manufacturing a chip capacitor, the present invention can be applied to a case of manufacturing another chip electronic component having an external electrode.

〔The invention's effect〕

As described above, the external electrode forming method for a chip electronic component according to the present invention is to fill the paste material in the recess of the mold, and dry, release, and fire the paste material, so that It can be attached to the main body with thickness accuracy, improving the dimensional accuracy of chip electronic parts.
It is possible to use a paste material that has a lower viscosity than the conventional method of deep coating, so there is no risk of entrapment of air bubbles, and it is possible to reliably prevent defective quality of chip electronic parts due to pinholes. Has a great effect.

[Brief description of drawings]

1 (a) to 1 (d) are process drawings showing an embodiment of the method of the present invention, FIG. 2 is an external view of a laminated ceramic capacitor, FIG. 3 is a sectional view thereof, and FIG. 4 shows a conventional method. FIG. 1 ... Chip capacitor (multilayer ceramic capacitor), 2 ... Main body, 3 ... External electrode, 4 ... Dielectric material, 5
...... Internal electrode, 6 …… Metal glaze conductor, 21 …… Support plate (support), 22 …… Concave, 23 …… Model, 24 …… Paste material, 24 ′ …… Cap paste.

Claims (1)

(57) [Claims] 1. A method for forming an external electrode of a chip electronic component, which is manufactured by forming an external electrode electrically connected to an electronic element on the outside of a main body enclosing the electronic element. After applying a release agent in the recess of a mold having a large number of recesses of geometrical dimensions, a low-viscosity paste material containing conductive particles is filled in each recess, and thereafter,
A large number of the main bodies held by the support are inserted into the respective recesses in a predetermined amount, dried in this state to apply the paste material to the main body, and then released to bake the paste material. A method for forming an external electrode for a chip electronic component, comprising: