JPH08222478A - Chip-type electronic part - Google Patents

Abstract

PURPOSE: To provide a chip-type electronic part, wherein a ceramic element is protected against cracking when the electronic part is mounted by soldering. CONSTITUTION: A chip-type electronic part is composed of a ceramic element and outer electrodes formed on the end faces of the ceramic element, and at least a belt-like electrode 2 which extends vertical to the mounting surface of a board and a glass film 3 joined to the electrode 2 are formed on the end face of the ceramic element where the outer electrode is formed, whereby stress applied onto the ceramic element due to the shrinkage of solidifying solder at mounting can be lessened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type electronic component, and more particularly to the structure of its external electrodes.

[0002]

2. Description of the Related Art For example, in a chip type electronic component such as a laminated ceramic capacitor, as shown in FIG. 4A, a plurality of internal electrodes 20 are arranged so as to overlap with each other via ceramic layers and are alternately arranged. As shown in FIG. 4 (2), the ceramic element 10 having a structure in which both end faces are drawn out, and a conductive paste for external electrodes is applied and baked so as to cover the internal electrodes drawn out in both end faces. And an external electrode 30 that is electrically connected to the internal electrode.

However, when such a chip-type electronic component is soldered and mounted on the electrode land of the printed circuit board, the molten solder rises along the surface of the external electrode 30 of the electronic component and solidifies to form a fillet. A crack may occur in the ceramic element 10 due to the stress of the solidification shrinkage of the solder formed. In addition, at this time, normally, the amount and the deposition rate of the solder do not easily become constant. Therefore, the solder on both sides of the external electrode 30 becomes non-uniform, and the chip type electronic component is attached in an inclined state. Problems may occur. This problem is likely to occur particularly when the size of the chip-type electronic component is small.

Therefore, in order to solve the above problem, as shown in FIG. 5, it is possible to prevent the molten solder from rising along the surface of the external electrode 30 of the chip type electronic component. There is a chip-type electronic component 12 in which the upper half of the electrode 30 is formed of a solder non-sticking layer 31 such as resin.

[0005]

However, in the chip-type electronic component 12 as described above, the solder adheres only to the lower half of the external electrode 30, and the amount of the solder adhered can be reduced and the fillet can be lowered. As the size of the electronic component 12 increases, a large amount of solder still adheres in the lateral width direction of the external electrode 30 of the electronic component 12 mounted by soldering. Therefore, as shown in FIG. 6, when soldering is performed on the electrode lands 61 of the printed circuit board 60, the solidifying and contracting stress of the solder 50 acts directly on the ceramic element 10 through the external electrodes 30 in the direction of the arrow in the figure. However, cracks 40 may occur in the ceramic element 10. The crack 40 may impair the electrical characteristics of the chip-type electronic component.

In order to solve the above problems, the present invention provides
An object of the present invention is to provide a chip-type electronic component that can prevent the ceramic element 10 from cracking when it is mounted by soldering.

[0007]

The present invention provides a chip-type electronic component having a ceramic element and an external electrode formed on the end surface of the ceramic element, wherein the end surface of the ceramic element on which the external electrode is formed is The chip-type electronic component is characterized in that at least one strip-shaped electrode extending in a direction perpendicular to a mounting surface and a glass film bonded to the strip-shaped electrode are formed.

[0008]

According to the present invention, since the external electrode is at least one strip-shaped electrode formed in the direction perpendicular to the surface to be mounted, the solder adhesion amount in the lateral width direction of the external electrode to be mounted is reduced. it can. Therefore, the absolute amount of solder that adheres to the external electrodes is reduced, and the stress applied to the ceramic element due to the solidification shrinkage of the solder during soldering can be reduced. Further, by forming the glass film so as to be bonded to the strip electrode, the strip electrode and the glass film are integrally fixed to the ceramic element, so that the solidification shrinkage stress of the solder applied to the strip electrode is applied to the glass film. Is also dispersed, and the stress applied to the ceramic element can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the embodiments shown in the drawings.

FIG. 1 is a partial perspective view of a monolithic ceramic capacitor which is a chip type electronic component of an embodiment of the present invention. As shown in FIG. 1, three strip-shaped electrodes 2 as external electrodes and two strip-shaped glass films 3 are provided on the end surface of the ceramic element 1 in a direction perpendicular to the lower surface (mounting surface) thereof. It has an external electrode structure formed alternately. Also, FIG.
FIG. 6 is a partial perspective view of a monolithic ceramic capacitor which is a chip-type electronic component of another embodiment of the present invention. As shown in FIG. 2, three strip-shaped electrodes 2 as external electrodes and four strip-shaped glass films 3 are provided on the end surface of the ceramic element 1 in a direction perpendicular to the lower surface (mounting surface) thereof. It has an external electrode structure formed alternately.

Next, a method of forming external electrodes of the monolithic ceramic capacitor shown in FIG. 1, which is an embodiment of the present invention, will be described. First, as shown in FIG. 3A, the ceramic element 1 is prepared. Inside the ceramic element 1, a plurality of internal electrodes 4 are arranged so as to overlap each other with a ceramic layer interposed therebetween, and are alternately drawn out to the end surface of the ceramic element 1. The plurality of internal electrodes 4 drawn out to the end surface are electrodes on one side of the capacitor.

Next, as shown in FIG. 3B, the end surface from which the internal electrode 4 is drawn is connected to the internal electrode 4 in a direction perpendicular to the lower surface (mounting surface) of the ceramic element 1. The three strip electrodes 2 thus formed are formed at predetermined intervals. The strip-shaped electrode 2 is formed by applying a general conductive paste for an external electrode, which is a mixture of a metal component, a glass component, and a resin, and firing the paste at a predetermined temperature.

Next, as shown in FIG. 3 (3), the two strip-shaped glass films 3 are covered with the three strip-shaped electrodes so as to cover the exposed internal electrodes 4 and come into contact with the strip-shaped electrodes 2. It forms between 2. The glass film 3 is formed by applying a glass paste in which a glass component and a resin are mixed and firing the paste at a predetermined temperature.

The conductive paste is applied and fired as shown in FIG.
As shown in FIG. 3, not only the end face 1a of the ceramic element 1 but also one or both of the end face and the two faces 1b and 1c connected to the end face may be performed. The metal component of the conductive paste is, for example, Ag, Pd, Ag / Pd, C.
u, Ni, etc. are used. The firing temperature of the conductive paste is appropriately set according to the material of the metal component. Also,
The number of strip electrodes 2 is not limited to three, and at least one is sufficient.

The shape of the glass film is not limited to the strip shape, and may be any shape as long as it is in contact with the strip electrode 2. The glass component of the glass paste is
It is only necessary to select one that can be easily bonded to the strip electrode 2, and it is preferable to use one having the same quality as the glass component used in the conductive paste.

The strip electrode 2 may be formed after the glass film 3 is formed first. In addition, it is preferable that, of the firing temperature for forming the glass film 3 and the firing temperature for forming the strip electrode 2, the one having a higher firing temperature is formed first. When the firing temperature for forming the glass film 3 and the firing temperature for forming the strip electrode 2 are the same, the firing can be performed once.

Next, in order to confirm the effect of the chip-type electronic component of the present invention, a relatively large L dimension of 5.7 mm,
The chip-type electronic component (multilayer ceramic capacitor) of the embodiment of the present invention shown in FIG. 1 having a W dimension of 2.8 mm and a T dimension of 2.8 mm and the conventional chip-type electronic part (multilayer ceramic shown in FIG. 5). The experiment was conducted using 100 capacitors each. In the chip type electronic component of the embodiment of the present invention, the strip electrodes 2 containing three Ag and connected to the internal electrodes 4 are provided on both end faces of the ceramic element 1 so that the intervals between them are 0.5 mm. A strip-shaped glass film 3 was formed between the strip-shaped electrodes 2 and a glass paste having a glass component of PbO as a main component was applied. Also,
In the conventional chip-type electronic component, a solder resist made of epoxy resin was applied to the upper half of the external electrode 30 and heat-cured to form the solder non-adhesive layer 31. In all cases, the total exposed area of the external electrodes is the same.

Next, one each of the above-mentioned embodiment and the conventional example
00 chip-type electronic components are mounted on a circuit board coated with solder paste and placed in a reflow oven at 270 ° C.
The solder paste was melted and soldered, and a solder heat resistance test was conducted. After that, it was visually inspected with a magnifying glass for cracks in the soldered ceramic elements 1 of the chip-type electronic components. As a result, no cracks were present in all 100 chip-type electronic components (multilayer ceramic capacitors) of the examples of the present invention, and the electrical characteristics were not impaired. On the other hand, the conventional example has 10
16 of 0 cracks were present. Note that FIG.
The results similar to those of the above-described embodiments can be obtained for the other embodiments shown in FIG. Further, in the chip-type electronic component of the present embodiment, in the solder heat resistance test, the molten solder rises along the surface of the strip electrode 2 to the upper side of the strip electrode 2 and solidifies to form a fillet, Since the width of the strip electrode 2 is narrow, the amount of solder adhered to the mounted strip electrode 2 in the lateral width direction can be reduced, and as a result, the ceramic element 1 was not cracked.

Therefore, it can be seen that the electronic parts obtained according to the examples of the present invention have excellent solder heat resistance.

[0020]

As described above, according to the present invention, the stress applied to the ceramic element 1 due to the solidification shrinkage of the solder at the time of mounting by soldering can be reduced, so that the ceramic element 1
It is possible to prevent cracks from entering. Therefore, it is possible to provide a highly reliable chip-type electronic component as a surface mount component.

[Brief description of drawings]

FIG. 1 is a partial perspective view of a monolithic ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a partial perspective view of a monolithic ceramic capacitor according to another embodiment of the present invention.

FIG. 3 is an explanatory view of a manufacturing process of the embodiment of FIG.

FIG. 4 is a perspective view showing the appearance of a conventional monolithic ceramic capacitor.

FIG. 5 is a perspective view of a conventional chip-type ceramic electronic component.

FIG. 6 is an explanatory diagram showing a state in which cracks are formed in a ceramic element when mounted on a substrate.

[Explanation of symbols]

 1 ... Ceramic element 2 ... Strip electrode 3 ... Glass film 4 ... Internal electrode

Claims (1)

[Claims] 1. A chip-type electronic component having a ceramic element and an external electrode formed on an end surface of the ceramic element, wherein an end surface of the ceramic element on which the external electrode is formed comprises:
A chip-type electronic component, wherein at least one strip-shaped electrode extending in a direction perpendicular to a surface to be mounted and a glass film bonded to the strip-shaped electrode are formed.