JP2007073882A - Chip-type electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip-type electronic component which prevents occurrence of defects by avoiding a greater stress from exerting to a chip substrate through the reduction of the rigidity of its side electrode. <P>SOLUTION: In the chip-type electronic component comprising the chip substrate to the side face of which the side electrode is formed, the side electrode adopts a two-layer structure comprising a first electrode layer and a second electrode layer that is more porous than the first electrode layer. In particular, the first electrode layer is formed by using electrode paste wherein the blending amount of glass frit is 10 vol% or below, and the second electrode layer is formed by using electrode paste wherein the blending amount of glass frit is 10 to 30 vol%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chip-type electronic component, and more particularly to a chip-type electronic component having a feature in the structure of an electrode portion.

  2. Description of the Related Art Conventionally, chip-type electronic components use a chip substrate made of an alumina ceramic substrate having a rectangular shape as a base. Side electrodes are formed on a pair of opposing surfaces of the chip substrate, and the side electrode portions are connected to external connection terminals. It is used as.

  The side electrode is usually a liquid electrode paste formed by mixing a metal powder, glass frit, an organic solvent called a binder, and a small amount of additives, and then applied to the side electrode forming portion of the chip substrate. The metal powder is sintered by passing the chip substrate through a firing furnace.

  As the metal powder, copper or silver is often used. As shown in FIG. 2, after the side electrodes 200 are formed on both sides of the chip substrate 100, the nickel plating film 300, A solder plating film 400 is formed to constitute an external electrode terminal. A tin plating film may be used in place of the solder plating film 400.

  The chip substrate 100 of FIG. 2 shows the case of a chip-type capacitor, which is formed by laminating and sintering a plurality of ceramic green sheets coated with an electrode paste as an internal electrode. Reference numeral 500 denotes an internal electrode.

In such a chip type electronic component, in the case of the chip type capacitor shown in FIG. 2, the laminated ceramic green sheets are sintered to form the chip substrate 100 having the internal electrodes 500, and this chip substrate 100 Since the plating film is formed on the side electrode 200 provided on the side surface, there is a possibility that hydrogen adsorption may occur in the internal electrode 500 during the plating process. Therefore, the side electrode 200 has a two-layer structure. It has also been proposed to suppress hydrogen adsorption by forming it as thick as possible (see, for example, Patent Document 1).
JP 09-007877 A

  However, when the side electrode is formed thick in order to prevent hydrogen adsorption, the rigidity of the side electrode is further increased, and the chip-type electronic component comprising the chip substrate having the highly rigid side electrode is replaced with the side electrode portion. When mounted on a mounting board via solder or tin provided on the mounting board, the influence of the bending of the mounting board or vibration of the mounting board directly acts on the chip board via the highly rigid side electrode, There is a possibility that damage such as cracks may occur due to large stress acting on the chip substrate.

  In view of such a current situation, the present inventors have made an emergency development to prevent the occurrence of defects in the chip-type electronic component by reducing the rigidity of the side electrode and preventing the large stress from acting on the chip substrate. The present invention has been achieved.

  In the chip-type electronic component according to the present invention, in the chip-type electronic component comprising the chip substrate having the side electrode formed on the side surface, the side electrode has a first electrode layer provided on the lower layer side, and the first electrode layer. A two-layer structure of a second electrode layer provided on the upper layer side as a porous material was used.

  Further, the first electrode layer is formed using an electrode paste with a glass frit content of 10 vol% or less, and the second electrode layer is an electrode paste with a glass frit content of 10 to 30 vol%. It is also characterized by being formed using.

  According to the first aspect of the present invention, in the chip-type electronic component comprising the chip substrate having the side electrode formed on the side surface, the side electrode comprises the first electrode layer provided on the lower layer side and the first electrode layer. In addition, since the porous structure of the second electrode layer provided on the upper layer side is made porous, the porous second electrode layer functions as a buffer layer, so that a large stress acts on the chip substrate. Therefore, it is possible to suppress the occurrence of defects due to bending such as cracks in the chip-type electronic component.

  According to a second aspect of the present invention, in the chip-type electronic component according to the first aspect, the first electrode layer is formed using an electrode paste having a glass frit content of 10 vol% or less, The electrode layer is formed using an electrode paste having a glass frit content of 10 to 30 vol%, thereby ensuring sufficient moisture resistance and long-term reliability while functioning the second electrode layer as a buffer layer. be able to.

  The chip-type electronic component according to the present invention is a chip-type electronic component using a chip substrate having a side electrode formed on the side surface as a base, and the side electrode has a two-layer structure of a first electrode layer and a second electrode layer. In particular, the second electrode layer is provided on the upper layer side of the first electrode layer and is more porous than the first electrode layer.

  Thus, by providing the second electrode layer as a porous layer on the upper layer side of the first electrode layer, the second electrode layer can function as a buffer layer.

  Therefore, when the chip-type electronic component is mounted on the mounting substrate, when the mounting substrate is bent, the influence of the bending can be mitigated by the second electrode layer, and the chip substrate is damaged such as a crack. Can be prevented from occurring.

  In addition, by adjusting the thickness of the side electrode portion according to the thickness of the second electrode layer, it is possible to balance the stress relaxation function by the second electrode layer, moisture resistance, adhesion, and the like.

  The chip-type electronic component of the present invention is not limited to the chip-type capacitor schematically shown in FIG. 1, but may be a chip-type resistor, a chip-type inductor, or a so-called network electronic component in which these are combined. As described above, the present invention can be applied to any one in which the side electrode is formed on the side surface of the chip substrate serving as the base.

  The embodiment of the present invention will be described in more detail using a chip capacitor schematically shown in FIG. This chip type capacitor is based on a chip substrate 10 formed by laminating a plurality of ceramic green sheets coated with an electrode paste serving as an internal electrode in a predetermined shape, and firing the laminated body. Inside the chip substrate 10, a plate-like internal electrode 11 is laminated via a dielectric 12 to constitute a capacitor.

  One end of the internal electrode 11 is exposed from the chip substrate 10, and the side electrode 14 is formed on the exposed surface 13 where the internal electrode 11 is exposed.

  In particular, the side electrode 14 has a two-layer structure of a first electrode layer 14a and a second electrode layer 14b. The first electrode layer 14a is formed on the exposed surface 13, and then the second electrode is formed on the first electrode layer 14a. The layer 14b is formed, and the lower layer side is the first electrode layer 14a and the upper layer side is the second electrode layer 14b.

  A nickel plating film 15 and a solder plating film 16 are formed on the upper surface of the side electrode 14 by plating to constitute an external electrode terminal. Instead of the solder plating film 16, a tin plating film may be used.

  The first electrode layer 14a is formed by applying a liquid first electrode paste formed by mixing conductive metal powder, glass frit, an organic solvent, and a small amount of additive to the exposed surface 13 of the chip substrate 10. It is formed by sintering.

Copper powder or silver powder can be used as the conductive metal powder, and copper powder is used in the present embodiment. For the glass frit, PbO, SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO or the like can be used. In this embodiment, a mixture of PbO and SiO ₂ was used.

  The blending amount of the glass frit in the first electrode paste is 10 vol% or less as a component ratio with the conductive metal powder. This is the same as the electrode paste used for forming the conventional side electrode.

  The first electrode layer 14a is formed by applying the first electrode paste to the exposed surface 13 of the chip substrate 10 and baking it at 700 to 900 ° C. in a nitrogen atmosphere.

  The first electrode layer 14a is preferably formed as thin as possible in order to make the rigidity of the side electrode 14 portion as small as possible. In this embodiment, the thickness after baking by sintering is about 10 μm. If possible, a thinner one is desirable.

  The second electrode layer 14b is formed by applying a liquid second electrode paste formed by mixing conductive metal powder, glass frit, an organic solvent, and a small amount of additive on the first electrode layer 14a. It is formed by sintering.

As the conductive metal powder, the same conductive metal powder as that of the first electrode paste is used, and in this embodiment, the copper powder is used. For the glass frit, PbO, SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , ZnO or the like can be used. In this embodiment, a mixture of PbO and SiO ₂ was used. In order to make the second electrode layer 14b porous, it is desirable to adjust the composition of the glass frit.

  The compounding quantity of the glass frit in the 2nd electrode paste is 10-30 vol% as a component ratio with electroconductive metal powder.

  By applying this second electrode paste onto the first electrode layer 14a and firing at 400 to 600 ° C. in a nitrogen atmosphere, the second electrode layer 14b having a porous state can be formed.

  The second electrode layer 14b may be formed while adjusting the side electrode 14 portion to have a predetermined thickness. In this embodiment, the thickness after baking by sintering is about 100 μm.

  By providing the porous second electrode layer 14b between the first electrode layer 14a and the nickel plating film 15 as a plating film, the second electrode layer 14b functions like a cushion and is connected via an external connection terminal. Thus, the external force applied to the chip capacitor can be relaxed, and the chip capacitor can be prevented from being damaged such as a crack.

  Finally, the quality characteristic test result when the blending amount of the glass frit in the second electrode paste is changed will be described.

  Here, an electrode paste in which the blending amount of the glass frit is 5 vol%, 10 vol%, 15 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, 40 vol% as a component ratio with the conductive metal powder is generated. The second electrode layer 14b was formed using each electrode paste, and after the nickel plating film 15 and the solder plating film 16 were formed under the same conditions, a moisture resistance test, a temperature cycle test, and a deflection test were performed.

  In the moisture resistance test, the resistance between the electrodes of 30 chip capacitors each was measured, and the number below 1000ΩF was counted.

  In the temperature cycle test, 50 chip capacitors each were processed under test conditions of −55 ° C./125° C. and 1000 cycles to determine the incidence of defective products.

  In the bending test, a deflection amount of 5 mm was added to ten chip capacitors each, and a chip capacitor having a capacity reduction of a specified amount or more was determined as a defective product, and the occurrence rate of defective products was determined.

  As shown in Table 1, when the blending amount of the glass frit is 5 vol%, the moisture resistance is not sufficient, and when the blending amount of the glass frit is 35 vol% or more, the long-term reliability and the bending resistance are not sufficient. Therefore, the blending amount of the glass frit in the second electrode paste to be the second electrode layer 14b is desirably 10 to 30 vol%.

  Further, from the results of Table 1, it is clear that the moisture resistance is not sufficient when the blending amount of the glass frit is small, and the balance with the internal electrode 11 located on the lower surface of the first electrode layer 14a. Therefore, the blending amount of the glass frit in the first electrode paste to be the first electrode layer 14a is desirably 5 to 10 vol%.

It is a longitudinal cross-sectional schematic diagram of the chip-type electronic component concerning embodiment of this invention. It is a longitudinal cross-sectional schematic diagram of the conventional chip-type electronic component.

Explanation of symbols

10 Chip substrate
11 Internal electrode
12 Dielectric
13 Exposed surface
14 Side electrode
14a First electrode layer
14b Second electrode layer
15 Nickel plating film
16 Solder plating film

Claims (2)

In a chip-type electronic component consisting of a chip substrate with side electrodes formed on the side surfaces,
The side electrode has a two-layer structure of a first electrode layer provided on the lower layer side and a second electrode layer provided on the upper layer side as being more porous than the first electrode layer. Type electronic components. The first electrode layer is formed using an electrode paste having a glass frit content of 10 vol% or less,
2. The chip-type electronic component according to claim 1, wherein the second electrode layer is formed using an electrode paste having a glass frit content of 10 to 30 vol%.

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