JPS63257211A - Method of forming external electrode of chip type electronic component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming external electrodes in chip electronic components such as chip capacitors, chip resistors, and chip coils.

[Conventional technology]

An example of a chip electronic component formed by encapsulating an element in ceramics is a multilayer ceramic capacitor (hereinafter referred to as a chip capacitor) that uses ceramics as a dielectric. Such chip capacitors were developed to obtain large capacitance capacitors in a small size, and usually have a second capacitor.
It has an appearance as shown in the figure. That is, the chip capacitor 1 is visually composed of a main body 2 and external electrodes 3 formed at both ends of the main body 2, and the main body 2 has a dielectric material 4 inside, as shown in FIG. Internal electrodes 5 electrically connected to the external electrodes 3 are arranged in a comb-teeth shape, and a dielectric material 4 is filled between adjacent internal electrodes 5. This type of chip capacitor is very small and is generally mounted by directly soldering the external electrode 3 to a circuit board.

The chip capacitor I having the above structure has conventionally been manufactured as follows.

First, a slurry is formed by mixing ceramic dielectric powder, a resin such as acrylic or polyvinyl butyral, and a solvent such as water or trichloroethane.
It is coated to a thickness of μm and further dried to form a so-called green sheet. Next, an internal electrode paste containing palladium or the like is printed on this green sheet, and these green sheets are stacked so that internal electrodes 5 facing each other are formed alternately, and then pressed to form a paste with a thickness of 0.1 to 3, Q.
After crimping at a pressure of t/cnl, each chip is cut, beta-outed, and fired (1300°C) to obtain a chip-shaped main body 2.

Thereafter, as shown in FIG. 4, a large number of main bodies 2 are arranged and attached to a support plate 10 made of metal, resin, etc., and placed in a bath 16 of external electrode paste 15 made of highly viscous paste, palladium paste, etc. Then, the end of each main body 2 held on the support plate 10 is dipped, dried and fired (800° C.) to form a metal glaze conductor 6. The support plate 10 is formed by fixing a gas plate 12 having a large number of mounting holes If to a base 14 via a double-sided adhesive tape 13, and a chip-shaped main body 2 inserted into the mounting holes 11 is attached to both sides. Since it is temporarily fixed to the adhesive tape 113, after dip-coating the external electrode paste 15 on one end and letting it dry, turn each main body 2 upside down and hold it on the support plate 10, and do the same in the same way. Dip coating, drying, and subsequent baking are performed to form metal glaze conductors 6 at both ends of the main body 2. Finally, by forming a nickel plating layer 7 on the surface of the metal glaze conductor 6 and further forming solder plating N8 on the surface of this nickel plating layer 7, external electrodes 3 are provided at both ends of the main body 2. A chip capacitor 1 is completed.

Of 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 scratches, and this nickel plating M7
The solder plating layer 8 formed on the surface is for improving solderability, that is, solder wettability.

[Problem that the invention seeks to solve]

By the way, the conventional method for forming external electrodes in chip electronic components such as chip capacitors is to dip the end of the main body 2 into the external electrode paste 15 in the bathtub 16, as described above. Squeegeeing is performed along the paste, but even if squeegeeing is performed, variations in the amount of coating due to dipping tend to occur, resulting in poor thickness accuracy of the external electrode 3, which makes it difficult to improve the dimensional accuracy of chip electronic components. there were. In addition, since it is necessary to use a highly viscous external electrode paste 15 in the bathtub 16 in order to ensure a certain amount of coating, air bubbles are likely to be drawn in during the above-mentioned squeezing, and these air bubbles can be applied to the metal glaze conductor 6. As a result of the formation of pinholes, plating liquid such as nickel or solder penetrates into the pinholes, causing a quality defect in the chip capacitor 1 as a finished product.

The present invention has been made in view of the problems of the prior art described above, and its purpose is to provide a chip electronic component that can improve dimensional accuracy and is free from the risk of quality defects due to inclusion of air bubbles. An object of the present invention is to provide a method for forming an external electrode.

[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 manufactured by forming an external electrode conductive to the electronic element on the outside of a main body containing an electronic element. After applying a mold release agent to the recesses of a mold body having a number of recesses with internal dimensions approximately equal to the external dimensions of the mold, a low-viscosity paste material containing conductive particles is filled into each recess, and After that, a predetermined amount of each of the plurality of bodies held by a support is inserted into the recesses, dried in this state to coat the paste material on the bodies, and then released from the mold to release the paste material. Its distinctive feature lies in the fact that it is fired.

(Function) In other words, the external electrode forming method in which the paste material is filled into the recesses of the mold body, dried, released from the mold, and fired as described above allows the paste material to be applied to the main body of the chip electronic component with high thickness accuracy. Since it is possible to improve the dimensional accuracy of the chip electronic component, and because it is not a dip coating, a paste material with low viscosity can be used, which eliminates the risk of air bubbles being drawn in and the occurrence of pinholes. Avoided.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

This example shows a method for forming external electrodes of a chip capacitor. First, as shown in FIG. The main bodies 2 of the chip capacitors arranged through a sieve are attached to the capacitors, and one end of each main body 2 is made to protrude from the support plate 21 by a predetermined amount. As described above, the main body 2 is formed by stacking green sheets printed with internal electrode paste, pressing them together, cutting them into chips, and then firing or the like.

On the other hand, before and after the above step, as shown in FIG. 1(b), a mold release agent is applied in each recess 22 of a mold body 23 made of metal or the like having a large number of recesses 22. In addition, conductive particles (
Paste material 24 containing silver, palladium, etc.), glass frit, solvent, etc. in a predetermined ratio is applied to these recesses 22.
After filling, squeegeeing is performed using the squeegee member 25. Here, the internal dimensions of each recess 22 are set to be approximately equal to the external dimensions of the external electrode of the chip capacitor, more precisely, the external dimensions of the metal glaze conductor of the external electrode. The paste material 24 filled in is
It uses a material with lower viscosity than conventional external electrodes.

Next, the surface of the support body 21 on the protrusion side of the main body 2 is made to face the surface of the mold body 23 on which the paste material 24 is filled in the recess 22 on the side where the recess 22 is formed, and each After setting the main body 2 to be positioned above each recess 22, as shown in FIG.
Insert a predetermined amount into 2.

Then, the ends of the main bodies 2 are dried while being inserted into the recesses 22, the paste material 24 is applied to the ends, and the molds are released. As shown in FIG. A cap-like paste 24' is formed on each integral part.

In addition, since a mold release agent is applied in advance to the inside of the recess 22,
The paste material 24 is securely adhered to the body 2 when it dries and the solvent evaporates.

In this way, one end of the main body 2 is covered with a cap-like paste 24'.
Once formed, the end protruding from the support plate 21 is pushed in to make the other end protrude, and the above steps are repeated to form a similar cap-shaped paste 24' on the other end side. . After that, the cap-shaped paste 24' formed on both ends of the main body 2 is fired at 800 to 900°C, and this firing process causes the cap-shaped paste 24'
Since the resin and plasticizer contained therein are burnt and removed and the glass frit is melted, each cap-shaped paste 24' becomes a metal glaze conductor fixed to the surface of the main body 2 with high adhesion strength. becomes.

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 process is formed in the recess 22 of the mold body 23.
The cap-shaped paste 24' can be formed into a predetermined shape and a predetermined thickness by setting the cap-like paste 24' to an appropriate size, that is, a size that takes into account shrinkage due to drying of the paste material 24. It has superior thickness accuracy compared to conventional external electrodes, which improves the dimensional accuracy of chip capacitors.

Furthermore, in the conventional dip coating method, it is necessary to increase the viscosity of the external electrode paste, which causes a problem of air bubbles being drawn in during squeegeeing. Since it is dried and applied to the main body 2, a material with relatively low viscosity can be used, so there is no risk of air bubbles being drawn in during squeezing, and pinholes caused by air bubbles are avoided, resulting in stable quality. Chip capacitors are now available.

Furthermore, in the case of the conventional method of holding the main body 2 using double-sided adhesive tape, the work of flipping a large number of main bodies 2 after dip coating one end and drying was complicated.
As in this embodiment, if the main body 2 is held using a support plate 21 made of silicone rubber or the like having a large number of through holes 20,
By pressing the main body 2 after forming the cap-like paste 24' on one end, the other end can be made to protrude from the support plate 21, and there is no need to turn the main body 2 over, improving workability. There is.

In the above embodiment, only the case of manufacturing a chip capacitor was described, but the present invention can also be applied to the case of manufacturing other chip electronic components having external electrodes.

〔Effect of the invention〕

As explained above, the method for forming external electrodes of a chip electronic component according to the present invention involves filling the base material into the recess of the mold body, drying, molding, and firing, so that the base material is It can be applied to the main body with precise thickness, improving the dimensional accuracy of chip electronic components, and since it is possible to use a base material with lower viscosity compared to the conventional method of dip painting, there is no risk of air bubbles being drawn in. There is no leakage, and quality defects in chip electronic components caused by the occurrence of pinholes can be reliably prevented, resulting in remarkable effects.

[Brief explanation of drawings]

Figures 1 (a) to (d) are process diagrams showing one embodiment of the method of the present invention, Figure 2 is an external view of a multilayer ceramic capacitor, Figure 3 is a cross-sectional view thereof, and Figure 4 is an explanation showing a conventional method. It is a diagram. 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 body), 22... Recess, 23...
・・・・・・Mold body, 24・・・・・・Paste material, 24′ ・・・・・・Cap-shaped paste. Figure 1 (a) (C) (d)

Claims (1)

[Claims] In a method for forming an external electrode of a chip electronic component manufactured by forming an external electrode conductive to the electronic element on the outside of a main body containing an electronic element, a recess having an internal dimension substantially equal to the external dimension of the external electrode. After applying a mold release agent into the recesses of the mold body having a large number of molds, a low viscosity paste material containing conductive particles is filled into each recess, and then a large number of the mold bodies held on a support are filled with a low viscosity paste material containing conductive particles. A chip electronic component characterized in that a predetermined amount of the main body is inserted into each of the recesses, the paste material is applied to the main body by drying in this state, and then the paste material is baked after being released from the mold. External electrode formation method.