JP2000200731A - Laminated ceramic electronic component and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the laminated ceramic electronic component which can be treated by flow soldering, hardly has a microcrack, and is superior in stress resistance in and after substrate mounting. SOLUTION: This laminated ceramic electronic component is constituted by forming a laminated ceramic capacitor element 4 by forming external electrodes 3 on both exposed end surfaces of internal electrode layers 1 embedded in a ceramic capacitor sinter 2, connecting a metal copper plate 7 to the external electrodes 3 respectively, and coating the part of the ceramic capacitor element 4 with insulating resin 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic electronic component having excellent reliability and easy to mount on a substrate, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, multilayer ceramic electronic components having a square chip shape, such as multilayer ceramic capacitors, multilayer varistors, multilayer filters, etc., are widely used because of their small size, high performance and high density mounting.

As shown in FIG. 6, these rectangular chip-shaped electronic components have a rectangular parallelepiped ceramic sintered body 21.
Are embedded with a plurality of internal electrode layers 22, and one end of each of the internal electrode layers 22 is exposed on the end face of the ceramic sintered body 21 which faces alternately, and is connected to the external electrode 23. The external electrode 23 is formed by kneading a metal powder of silver, nickel, copper, or the like, a glass powder, a resin, and a solvent into a paste, applying the kneaded paste to the exposed end surface of the internal electrode layer 22, drying the glass, and melting the glass at a temperature generally lower. Is formed by firing at 600 to 800 ° C. Further, since the bonding between the external electrode 23 and the ceramic sintered body 21 after firing is mainly made of glass, the larger the amount of glass in the external electrode 23, the larger the external electrode 2
3 and the ceramic sintered body 21 have increased adhesive strength, but on the other hand, the solder wettability of the external electrode 23 is reduced, and there is a possibility that soldering failure may occur when soldering and mounting on the substrate. Further, silver is generally used because it can be fired in the atmosphere, but has a problem that the flow soldering method cannot be performed because it is diffused into high-temperature molten solder.

Therefore, as a means for solving these problems, as shown in FIG. 7, an external electrode 2 formed by printing silver is used.
By forming a nickel film 24 on the surface of No. 3 and a solder plating film 25 thereon by an electroplating method, silver diffusion is prevented and solderability is ensured.

However, there is a problem that the cost of the plating step is high, and in addition, the plating solution penetrates into the inside of the ceramic sintered body via the external electrode, thereby significantly reducing the reliability. Particularly, in the case of a zinc oxide-based varistor, the surface of the ceramic sintered body is conductive, so that there is a problem that the surface is plated up to the surface of the ceramic sintered body.

[0006] These multilayer ceramic electronic components also include:
Since the outer surface is ceramic, it is susceptible to mechanical shock and cracks are easy to occur.If even small cracks reach the internal electrode layer, moisture in the air permeates during use and shorts or insulation resistance decreases. Particularly, as shown in FIG. 8, the mounting board 26 may be bent or twisted by an external force as shown in FIG.
When the shrinkage occurs, the stress concentrates on the soldering portion 27 of the external electrode 23 and the ceramic sintered body 2
In addition, cracks 28 enter the inside of the electrode 1, and as a result, not only the electrical characteristics are deteriorated, but also the ion ions migrate between the internal electrode layers 22 due to the action of moisture and an electric field during use, resulting in a short circuit. Had become.

[0007]

As described above, when a conventional square chip-shaped multilayer ceramic electronic component is mounted on a substrate, as described above, it has many characteristics deterioration factors as described above, and is practically solved. Had a task to be done.

The present invention has been made in view of the above points, and has excellent solderability and solder heat resistance, can be flow-soldered, hardly causes micro cracks, and can be used during and after board mounting. An object of the present invention is to provide a highly reliable multilayer ceramic electronic component having excellent responsiveness and a method for manufacturing the same.

[0009]

In order to solve the above-mentioned problems, a multilayer ceramic electronic component according to the present invention is characterized in that ceramic green sheets and internal electrode layers are alternately laminated, and one of the internal electrode layers is formed. A ceramic sintered body formed by exposing and sintering the end portions alternately to the opposite end surface, an external electrode formed on the end surface of the ceramic sintered body where the internal electrode layer is exposed, and a metal connected to the external electrode A plate and an insulating resin covering the entire surface of the ceramic sintered body except for the surface of the metal plate.

In the multilayer ceramic electronic component of the present invention,
Since the connection part to the board is a metal plate with good solderability connected to the external electrode, good flow soldering is possible as well as good reflow soldering regardless of the soldering method and conditions At the same time, since the surface of the ceramic sintered body is covered with the resin, cracks will not occur even if there is a collision between parts with a vibration feeder or the like or an impact of a suction nozzle of a chip mounter.

Therefore, there is no restriction in mounting the substrate,
In addition, the characteristic deterioration factor is eliminated, and the effect of obtaining a highly reliable multilayer ceramic electronic component can be obtained.

A second aspect of the present invention relates to a manufacturing method for efficiently manufacturing the multilayer ceramic electronic component according to the first aspect of the present invention. A plurality of internal electrode layers are buried, one end of each of these internal electrode layers is alternately exposed to the opposite end face, and a plurality of ceramic elements having external electrodes formed on the exposed end face are spaced at a constant interval between the plurality of ceramic elements. Holding, the contact portion between the external electrode portion and the metal plate is bonded and integrated via a conductive adhesive, and thereafter, the three surface portions that are the gap between the pair of metal plates are closed with a lid, and the remaining one surface is covered. A liquid epoxy resin for casting is injected through the opening of-and cured, and cut in advance along a grid line serving as a cutting line attached to the metal plate surface, to obtain a unitary multilayer ceramic electronic component. I do.

According to the method of manufacturing a multilayer ceramic electronic component of the present invention, a plurality of multilayer ceramic elements are fixed between metal plates and cut once along a grid line which is a cutting line previously attached to the metal plate. Thus, it is possible to obtain a large number of highly reliable multilayer ceramic electronic components.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer ceramic electronic component of the present invention is obtained by forming a slurry into a green sheet by a doctor blade method, screen-printing an electrode paste on the green sheet in a pattern, and punching the green paste into a predetermined size. After cutting, a plurality of dummy sheets are stacked while being aligned so that they are alternately exposed on the cut surface, and a predetermined number of dummy sheets not printed up and down are stacked, and heated and pressed to form a laminate by pressure bonding and integration. Thereafter, the laminated body is cut and sintered into individual chips at predetermined positions to produce a laminated ceramic sintered body, and external electrodes are provided on both end surfaces of the laminated ceramic sintered body where the internal electrodes are exposed. To form a multilayer ceramic element.

Next, one surface of an external electrode is adhered to the center of the mesh on a metal plate provided with a plurality of meshes formed by grid-like ruled lines serving as cutting lines, and a plurality of laminated ceramic elements are fixed. Further, a metal plate formed in the same manner as described above is adhered to the other surface of the external electrode by the same method, sandwiched between the metal plates, and the metal plate and a plurality of laminated ceramic elements are integrated. .

Next, a three-sided portion, which is a gap between the pair of metal plates, is closed with a lid, and a casting resin is injected and cured from the remaining one side of the opening. Thereafter, the lid is removed to form an integrated product. I do.

Next, the metal plate is fixed to the external electrodes by cutting along the grid line which is a cutting line attached to the metal plate surface of the integrated product, and the entire surface of the multilayer ceramic element is covered with an insulating resin. To obtain a chip-shaped multilayer ceramic electronic component.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A multilayer ceramic capacitor will be described below with reference to the drawings. First, as the dielectric composition, for example, a lead-based composite perovskite structure composed of three components of lead magnesium niobate, lead zinc niobate, and lead titanate, and further substituting a part of the lead with barium A powder was made. Next, a slurry obtained by adding and mixing a polybutyral resin, DOP and a solvent as a binder to the powder is formed into a green sheet having a thickness of 15 μm by a doctor blade method, and the green sheet contains an electrode containing silver / palladium. The paste is screen-printed in a pattern, punched out to a certain size, and the printed pattern is stacked so as to be alternately exposed on the cut surface after cutting, and 100 sheets are stacked. The sheets are stacked, heated and pressed to be integrated by pressure bonding to form a laminate. Thereafter, the laminate is cut into individual chips at predetermined positions,
C. to form a ceramic capacitor sintered body. Electrode paste containing silver powder was applied to both end surfaces of the ceramic capacitor sintered body where the internal electrodes were exposed.
Baking at ℃ to form external electrodes, length 5.2mm, width 4.
A chip-type multilayer ceramic capacitor element having a thickness of 7 mm and a thickness of 1.5 mm is formed.

Next, as shown in FIG. 2, a 0.15 mm-thick plated with a composition of tin 90 / lead 10 and a thickness of 10 μm.
A 5.3 × 2.1 mm grid 6 formed by a grid-shaped ruled line 5 which is a 150 mm square and is a cutting line on both sides.
Using a metal copper plate 7 provided with
The external electrodes 3 of the chip-shaped multilayer ceramic capacitor element 4 obtained by the above-described means are provided at the centers of the respective meshes 6 obtained by the ruled lines 5 of the metal copper plate 7.
Is bonded and cured using a conductive adhesive 8 made of silver powder and resin, and a metal copper plate 7 formed in the same manner as described above is bonded to the other surface of the external electrode 3 by the same method. The metal copper plate 7 and a plurality of chip-shaped multilayer ceramic capacitor elements 4 are integrated with each other.

Next, a three-sided portion, which is a gap between the pair of metal copper plates 7, is closed with a lid (not shown), and a liquid epoxy resin for casting is injected and cured from the remaining one side of the opening, and the lid is closed. The removal is performed to form the integrated body 9 shown in FIG.

Next, the integrated material 9 is cut along a mesh 6 formed by the ruled lines 5 attached to the surface of the metal copper plate 7 with a cutter of a rotating diamond blade having a thickness of 0.3 mm. As shown in FIG.
mm, a width of 5.0 mm and a thickness of 1.8 mm are completed. In the figure, 1 is an internal electrode, 2 is a ceramic capacitor sintered body, and 10 is an insulating resin.

Next, Table 1 shows a comparative test of the product of the present invention (A) shown in FIG. 1 and the conventional structure (B) shown in FIG.

The test items and conditions are as follows.
The composition and internal electrode material of the conventional structural product (B) are the same as those of the present invention product (A). (1) Impact resistance: Two plastic tapper containers are prepared, and each of the present invention product and the conventional structure product is put in 100 pieces, and the product is vibrated for 10 seconds at an amplitude of 100 mm and 2 cycles / sec. The presence or absence of cracks on the surface was examined using a mirror, and those having cracks were judged to be defective. (2) Substrate bending resistance: a method shown in JIS C 6429 Annex 2. However, a test in which the amount of deflection was 3 mm was performed on each of 100 samples, and the capacitance was 1
Those which were reduced by 0% or more and those which had cracks were regarded as defective. (3) Heat cycle / moisture resistance composite test: JIS C
Each of the test substrates A specified in 6429 has 100
Each sample was soldered and the temperature was -55 ° C / + 125 ° C for 30
After a temperature cycle test of 100 cycles per minute, a DC bias of 25 V was applied at a temperature of 85 ° C. and a relative humidity of 85% for 50 minutes.
After continuous application for 0 hours, the withstand voltage (250% of the rated voltage), the capacitance, and the insulation resistance were measured. (4) Solder heat resistance: a method shown in Annex 3 of JIS C 6429. However, a test in which the solder temperature was 280 ° C. and the number of times of immersion was two was performed on each of 100 samples, and after the test, those having a portion where the electrode disappeared were regarded as defective.

[0024]

[Table 1]

In the above embodiment, a multilayer ceramic capacitor has been described as an example. However, it is needless to say that the present invention can be applied to a multilayer varistor, a multilayer filter or the like.

[0026]

As described above, according to the present invention, the solderability and the solder heat resistance are excellent, the flow soldering can be performed more easily than the reflow soldering, the micro cracks are less likely to occur, and the mounting of the circuit board can be easily performed. In addition, it is possible to provide a multilayer ceramic electronic component having excellent responsiveness after mounting and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a multilayer ceramic capacitor according to the present invention.

FIG. 2 is a plan view showing a metal copper plate according to the present invention.

FIG. 3 is a perspective view showing a state in which a multilayer ceramic capacitor element and a metal copper plate which are being manufactured according to the present invention are integrated.

FIG. 4 is a front view as seen from the direction of the arrow in FIG. 3;

FIG. 5 is a perspective view showing an integrated product formed by integrating a multilayer ceramic capacitor element and a metal copper plate during manufacturing according to the present invention and injecting and curing a resin between the metal copper plates.

FIG. 6 is a sectional view showing a multilayer ceramic electronic component according to a conventional example.

FIG. 7 is a cross-sectional view showing a multilayer ceramic electronic component according to another conventional example.

FIG. 8 is a cross-sectional view showing a failure state of a multilayer ceramic electronic component when a multilayer ceramic electronic component is mounted on a substrate and the substrate is bent according to a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 internal electrode layer 2 ceramic capacitor sintered body 3 external electrode 4 multilayer ceramic capacitor element 5 ruled line 6 grid 7 metal copper plate 8 conductive adhesive 9 integrated object 10 insulating resin

Continued on the front page F-term (reference) LL03 LL35 MM22 MM24

Claims (2)

[Claims] 1. A ceramic sintered body formed by alternately laminating ceramic green sheets and internal electrode layers, exposing one end of the internal electrode layers alternately to opposing end surfaces, and sintering the ceramic green sheets. An external electrode formed on the end face where the internal electrode layer of the body is exposed, a metal plate connected to the external electrode, and an insulating resin covering the entire surface of the ceramic sintered body except for the surface of the metal plate. Characterized multilayer ceramic electronic components. 2. A plurality of internal electrode layers are buried in a ceramic sintered body between a pair of metal plates, and one ends of the internal electrode layers are alternately exposed on opposing end faces, and the exposed ends are A plurality of laminated ceramic elements having external electrodes formed by being connected to the exposed ends of the internal electrodes on the surface of the ceramic sintered body that is located, maintaining a constant interval between the plurality of ceramic elements, A step of bonding and integrating the attached portion via a conductive adhesive, and injecting and curing an insulating resin into a gap between a plurality of laminated ceramic elements disposed between a pair of metal plates to form an integrated product And cutting along a mesh that is a cutting line previously attached to the metal plate surface of the integrated product,
A step of obtaining a unitary multilayer ceramic electronic component in which a metal plate is connected to an external electrode portion of the multilayer ceramic element and a ceramic sintered body portion is coated with an insulating resin. Manufacturing method.