JP2000182883A - Manufacture of laminated ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of an external electrode with high reliability that is electrically connected to internal electrodes. SOLUTION: This laminated ceramic capacitor has a sintered body, consisting of a plurality of layers of alternately laminated ceramic layers 1 and internal electrodes 2 and an external electrode 6 formed at the end part of the sintered body, so as to be electrically connected to the internal electrodes 2. To obtain an electrode 3 connected electrically to the end part of the internal electrodes 2 exposed on the end surface of the sintered body, an electrode 3 paste consisting of a pyrolytic organic metal body such as silver acetate, silver powder 9 and epoxy resin 10 is coated on the end part of the sintered body, and is then heated to pyrolyze the silver acetate and to cure the epoxy resin 10. By pyrolyzing the silver acetate, fine silver particles 8 are precipitated extensively the end part surface of the internal electrodes 2 and the silver powder 9 surface and in the cured resin 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer ceramic electronic component, and more particularly to a method for manufacturing an external electrode formed so as to be electrically connected to an internal electrode thereof.

[0002]

2. Description of the Related Art The prior art will be described with reference to a multilayer ceramic capacitor 15 shown in FIG.

[0003] According to a known manufacturing method, the ceramic layer 1
And a plurality of internal electrodes 2 mainly composed of metal powder are alternately superposed on each other, and a green laminate (not shown) is cut into a predetermined green chip shape, followed by firing to produce a sintered body. .

Next, the internal electrode 2 exposed on the end face of the sintered body
The paste of the electrode 11 is applied to the end of the sintered body so as to be electrically connected to the end, and is baked at a predetermined temperature to form the electrode 11.

Next, in order to ensure solderability, a nickel plating film 4 is formed on the surface of the electrode 11 by electrolytic plating, and a solder plating film 5 is further formed on the surface of the nickel plating film 4 to form an external electrode 12.
Is formed, and the multilayer ceramic capacitor 15 is completed.

In order to improve the adhesive strength between the electrode 11 and the sintered body, the electrode 11 containing metal powder and glass frit is used.
Is applied to the end of the sintered body at 700 to 900 ° C.
The internal electrode 2 and the electrode 11 were electrically connected to each other by baking at a temperature, and a strong electrode 11 was formed at the end of the sintered body. 4 and 5, instead of the baked electrode 11, a paste of a conductive electrode 16 made of a thermosetting resin 10 and a silver powder 9 is applied to the end of the sintered body, and then heated. Japanese Patent Application Laid-Open No. 3-27003 discloses a method for forming an electrode 16 by thermosetting a resin by using the method.

[0007]

In the multilayer ceramic capacitor 15 shown in FIG. 3, when the electrodes 11 are baked, the glass frit component contained in the paste for the electrodes 11 is diffused into the sintered body, and the glass frit is added to the end of the sintered body. The diffusion layer 13 is formed. Then, the laminated ceramic capacitor 15 having the electrodes 11 baked
When the solder 20 is mounted on the circuit board 19 of FIG. 6 and a bending stress is applied to the circuit board 19, the glass diffusion layer 13
The interface between the substrate and the non-glass diffusion layer 14 is the starting point of the destruction, and the multilayer ceramic capacitor 15 is destructed as shown in FIG. In order to prevent this, measures have been taken to lower the baking temperature of the electrode 11 and to make the glass diffusion layer 13 as thin as possible. However, the alloying between the internal electrode 2 and the electrode 11 is insufficient and the reliability of the electrical connection is reduced. There was a problem that.

The multilayer ceramic capacitor 1 shown in FIG.
8 can prevent breakage due to bending stress after the solder 20 is mounted on the circuit board 19, but since the curing temperature of the thermosetting resin 10 is low, alloying of the internal electrode 2 and the silver powder 9 does not progress, and the internal Since electrical conductivity is obtained only by mechanical contact between the end of the electrode 2 and the silver powder 9, there is a problem in reliability of electrical connection.

The present invention solves the above-mentioned conventional problems, and provides a method of manufacturing an excellent multilayer ceramic electronic component which withstands a bending stress and has a highly reliable electrical connection between an internal electrode and an external electrode. It is intended to do so.

[0010]

In order to achieve the above object, the present invention provides an external electrode which is electrically connected to an internal electrode at an end of a multilayer body in which a plurality of ceramic layers and internal electrodes are alternately laminated. When forming, a conductive external electrode paste containing a thermally decomposable organic metal body is applied to the end of the laminate, and then heated to thermally decompose the thermally decomposable organic metal body, and the metal component is exposed to the inner electrode end surface and the external electrode By obtaining reliable electrical continuity between the internal electrode and the external electrode via the deposited metal component, thereby obtaining a multilayer ceramic electronic component having excellent bending stress after solder mounting. is there.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to a first aspect of the present invention is directed to a laminated body in which a plurality of ceramic layers and internal electrodes are alternately laminated, and the end of the laminated body is electrically connected to the internal electrodes. In the multilayer ceramic electronic component having external electrodes formed so as to be formed, the external electrodes of the laminate are formed by applying a conductive external electrode paste containing a thermally decomposable organic metal body to an end of the laminate, and then heating and curing the paste. The present invention provides a method for manufacturing a multilayer ceramic electronic component in which a thermally decomposable organic metal body is thermally decomposed in step (1) and the metal component is deposited on the end surface of the internal electrode and in the external electrode. The thermally decomposable organometallic substance contained in the conductive external electrode paste applied to the end of the laminated body where the internal electrode end is exposed is thermally decomposed, and fine metal components are deposited on the internal electrode end surface and inside the external electrode. Let it. By ensuring good electrical connection between the internal and external electrodes via the deposited fine metal particles, and by forming external electrodes that do not generate a glass diffusion layer inside the multilayer ceramic electronic component, after solder mounting Has the effect of withstanding the bending stress of

The invention according to claim 2 of the present invention is characterized in that a material having a composition in which the decomposition temperature of the thermally decomposable organometallic substance contained in the conductive electrode paste used as the external electrode is lower than 350 ° C. is used. The method for manufacturing a multilayer ceramic electronic component according to claim 1. By using a compound having a decomposition temperature of 350 ° C. or less for the thermally decomposable organic metal body, even when a base metal material is used for the internal electrode of the multilayer ceramic electronic component, the base electrode end surface is formed at a low temperature at which the base metal is not oxidized. Decomposed fine metal components can be deposited in the external electrode, good electrical connection can be obtained between the internal electrode and the external electrode, and when the conductive external electrode paste contains a glass component Also, the diffusion layer of the glass component is formed only on the very surface layer, and has an effect that the bending stress is not reduced even when it is soldered on a circuit board or the like.

According to a third aspect of the present invention, there is provided the method for manufacturing a multilayer ceramic electronic component according to the first aspect, wherein silver acetate is used for the thermally decomposable organic metal body. This specifies an organometallic compound in which the decomposition temperature of the thermally decomposable organometallic body is lower than 350 ° C.

According to a fourth aspect of the present invention, a conductive external electrode paste comprising a thermosetting resin, a thermally decomposable organic metal body, and a metal powder is used.
It is a manufacturing method of the multilayer ceramic electronic component described. The use of the thermosetting resin has an effect that an external electrode having strong mechanical adhesive strength can be formed at the end of the multilayer ceramic electronic component.

(Embodiment 1) Hereinafter, an embodiment of the present invention will be described using a multilayer ceramic capacitor using internal electrodes mainly composed of nickel.

FIG. 1 is an enlarged view of a multilayer ceramic capacitor 7, and FIG. 2 is an enlarged view of an electrode 3 according to an embodiment of the present invention.

First, a green laminated body (not shown) in which a plurality of ceramic layers 1 and internal electrodes 2 mainly composed of nickel are alternately laminated in accordance with a known method of manufacturing a laminated ceramic capacitor, and then a predetermined size is obtained. To produce a green chip (not shown).

Next, the green chip was fired at a temperature of 1300 ° C. in a green gas atmosphere to produce a sintered body.

Next, 5 wt% of silver acetate as a thermally decomposable organic metal and 1 μm of silver powder 9 of 1 μm as metal powder are covered so as to cover both end surfaces of the sintered body with the end of the internal electrode 2 exposed.
An electrode paste of 15% by weight and thermosetting epoxy resin 10 is applied.

Thereafter, the sintered body to which the electrode paste was applied was held in a dryer at 350 ° C. for 40 minutes in the air to cure the epoxy resin 10 and thermally decompose silver acetate to form an electrode as shown in FIG. No. 3 was formed on both ends of the sintered body. The electrode 3 is
Fine silver particles 8 are deposited on the surface of the end of the internal electrode 2, on the surface of the silver powder 9, and in the epoxy resin 10 due to the thermal decomposition of silver acetate.

The heating temperature was set at 350 ° C. for the following reason. (1) Silver acetate (CH ₃ COOAg-R, R is an amine-based hydrocarbon compound) has a coordinate bond of CH ₃ COOAg group-R group, and is thermally decomposed at a temperature of 200 ° C. or less to form fine silver particles 8
Is precipitated. (2) Nickel oxidation of the internal electrode 2 is prevented. (3) The epoxy resin 10 secures sufficient adhesive strength to the end of the sintered body.

Although the amount of silver acetate is 5 wt%, the mixing ratio of silver acetate and silver powder 9 is arbitrarily changed according to the required electrode 3 film resistance and electrode 3 film thickness.

Next, in order to secure the solderability of the electrode 3, a nickel plating film 4 is formed on the surface of the electrode 3 by an electrolytic plating method, and a solder plating film 5 is further formed on the surface to form an external electrode 6. Thus, the multilayer ceramic capacitor 7 shown in FIG. 1 was completed.

The obtained multilayer ceramic capacitor 7-1
For 00 pieces, the capacitance at room temperature and the change in capacitance after dipping in a solder bath at 270 ° C. and soldering to the surface of the external electrode 6 were measured, and DC 50 V was applied in a wet bath at a temperature of 85 ° C. and a relative humidity of 85%. A change in capacitance was measured in a continuous conduction test at a voltage of 1000 hours. For comparison, a multilayer ceramic capacitor 18 in which an electrode 16 is formed using a conductive electrode paste obtained by adding 80 wt% of 1 μm silver powder 9 to a thermosetting epoxy resin 10 instead of the electrode paste of the present invention is also used as a conventional example. The above measurements were performed, and the results are shown in (Table 1).

[0025]

[Table 1]

As is clear from Table 1, the multilayer ceramic capacitor 7 of the present invention does not have a defect that the capacitance changes by ± 10% or more even after the soldering and after the continuous conduction test. On the other hand, the multilayer ceramic capacitor 18 obtained by adding only the silver powder 9 to the thermosetting epoxy resin 10 instead of the electrode 3 has a failure of 10% or more in the continuous conduction test. This is because the fine silver particles 8 precipitated by the thermal decomposition of silver acetate are the silver powder 9 added to the electrode 3 paste.
It has higher surface activity and chemically bonds more strongly to the inner electrode 2 end surface and the surface of the silver powder 9, and is widely dispersed in the thermosetting epoxy resin 10, and is good via the dispersed silver particles 8. It is considered that an electrical connection was obtained. On the other hand, when only the silver powder 9 was added to the thermosetting epoxy resin 10, the contact between the added silver powder 9 and the end of the internal electrode 2 and the silver powder 9 dispersed in the thermosetting epoxy resin 10 were removed. It is considered that the contact was thermally degraded and a defect occurred in the continuous energization test because of the electrical connection through the contact.

According to the present invention, the multilayer ceramic capacitor 7 using the internal electrode 2 made of a metal that is easily oxidized, such as a base metal, and the end portion of the internal electrode 2 are stable and excellent even in the heat treatment in the air. It is possible to form the electrode 3 that can secure a proper electrical connection.

Next, the multilayer ceramic capacitor 7
After performing the solder 20 mounting on the circuit board 19 for 0 pieces,
As shown in FIG. 7, the circuit board 19 is supported between two points of 90 mm, and a bending weight bar 21 is provided at the center opposite to the soldering surface.
And the circuit board 19 is moved at a load speed of 0.5 mm / sec.
A load was applied until the bending of the multilayer ceramic capacitor 7 before and after the test, and the change in the capacitance of the multilayer ceramic capacitor 7 before and after the test was measured. Further, as a comparative example, the same measurement was performed on the laminated ceramic capacitor 15 having the baked electrode 11 instead of the electrode 3 of the present invention, and the results are also shown in Table 2.

[0029]

[Table 2]

As is clear from Table 2, in the multilayer ceramic capacitor 7 of the present invention, there is no defective product whose change rate of the capacitance exceeds ± 10% in the bending stress test of the circuit board 19. On the other hand, the conventional multilayer ceramic capacitor 15 has a failure of 20% or more. As a result of observing the defective product under a microscope, the glass diffusion layer 13 at the end of the sintered body was found.
Cracks were observed at the interface between the glass and the non-diffusion layer 14.

From the above results, the internal electrode 2 was placed on the end face of the sintered body.
An electrode paste made of silver acetate, silver powder 9 and thermosetting epoxy resin 10 is used as a material of the electrode 3 electrically connected to the end portion, and silver acetate is thermally decomposed by heating after application to produce fine silver particles. By depositing 8 on the end surface of the internal electrode 2, on the surface of the silver powder 9, and inside the cured epoxy resin 10, a highly reliable electrode that withstands a continuous conduction test that ensures good electrical connection with the internal electrode 2. 3 is obtained, and the obtained multilayer ceramic capacitor 7 is soldered to the circuit board 19.
It can be seen that the electrode 3 having stable adhesive strength can be obtained even after performing a bending load test after the mounting. Further, since the electrode 3 is formed at a relatively low temperature, a stable electrical connection between the internal electrode 2 and the electrode 3 is ensured even when a readily oxidizable metal such as a base metal is used for the internal electrode 2. There is no occurrence of capacitance failure. Therefore, even when the base metal is used, it is not necessary to use a special gas at the time of baking the electrode 3, and the manufacturing cost of the multilayer ceramic capacitor 7 can be greatly reduced.

Although the present invention has been described using the multilayer ceramic capacitor 7, the present invention is not limited to the multilayer ceramic capacitor 7, but may be any electronic component having a structure in which an internal electrode and an external electrode are electrically connected. It can be applied to electronic components. In this embodiment, silver nitrate is used as the thermally decomposable metal body. However, any organic silver compound may be used as long as it is a compound that thermally decomposes in a temperature range of 350 ° C. or lower where nickel of the internal electrode 2 is not oxidized. Alternatively, the electrode 3 may be formed by using a conductive metal powder instead of the silver powder 9 or using another thermosetting resin instead of the thermosetting epoxy resin 10. Further, it is also possible to add a thermally decomposable organometallic substance to a baking electrode paste containing a glass frit.

[0033]

As described above, according to the present invention, the end of the internal electrode exposed at the end face of the multilayer ceramic electronic component is electrically connected to the internal electrode by using an electrode paste containing a thermally decomposable organic metal body. By forming the electrodes to secure stable and good electrical connection between the internal electrodes and the electrodes, even after applying the bending stress to the board after soldering the obtained multilayer ceramic electronic component to the circuit board, An electrode having stable adhesive strength can be formed. In addition, even in a heating process in air on a multilayer ceramic electronic component having an internal electrode formed of a base metal material, it is possible to form an electrode that ensures good electrical connection with the internal electrode.

[Brief description of the drawings]

FIG. 1 is a sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of the external electrode unit.

FIG. 3 is a cross-sectional view of a conventional multilayer ceramic capacitor using a firing electrode method.

FIG. 4 is a cross-sectional view of the multilayer ceramic capacitor according to the thermosetting electrode method.

FIG. 5 is a partially enlarged cross-sectional view of the thermosetting electrode portion.

FIG. 6 is a cross-sectional view of a multilayer ceramic capacitor using the burn-in electrode method broken in a circuit board bending stress test.

FIG. 7 is a conceptual diagram of a circuit board bending stress test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic layer 2 Internal electrode 3 Electrode 4 Ni plating film 5 Solder plating film 6 External electrode 7 Multilayer ceramic capacitor of this invention 8 Silver particle 9 Silver powder 10 Epoxy resin

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (4)

[Claims] 1. A multilayer ceramic electronic component comprising: a laminate in which a plurality of ceramic layers and internal electrodes are alternately laminated; and an external electrode formed at an end of the laminate so as to be electrically connected to the internal electrode. The external electrode on the end face of the laminate, after applying a conductive external electrode paste containing a thermally decomposable organic metal body to the edge of the laminate, thermally decompose the thermally decomposable organic metal body at the temperature during heat curing, A method for manufacturing a multilayer ceramic electronic component in which the metal component is formed in a state where the metal component is deposited on the end surface of the internal electrode and in the external electrode. 2. The decomposition temperature of a thermally decomposable organometallic substance contained in a conductive electrode paste used as an external electrode is 350.
The method according to claim 1, wherein a material having a composition lower than C is used. 3. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein silver acetate is used as the thermally decomposable organic metal body. 4. The method for producing a multilayer ceramic electronic component according to claim 1, wherein a conductive external electrode paste comprising a thermosetting resin, a thermally decomposable organic metal body, and a metal powder is used.