JP3036567B2 - Conductive chip type ceramic element and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive ceramic element such as a chip type NTC thermistor, PTC thermistor, varistor, inductor and the like which is surface-mounted on a printed circuit board or the like. More specifically, the present invention relates to a method for manufacturing a conductive chip type ceramic element.

[0002]

2. Description of the Related Art Conventionally, in a conductive chip type ceramic element such as a chip type thermistor, electrodes mainly composed of silver-palladium are baked on both ends of a conductive ceramic body. The reason for containing palladium in addition to silver in the electrode component is to prevent silver from eluting and disappearing in the solder when soldering the chip thermistor to the substrate, and to obtain solder heat resistance of the electrode. is there. However, when the content of palladium is increased, the adhesiveness of the electrode to the solder is reduced, and the fixing force of the thermistor to the substrate is weakened. Therefore, the content of palladium has a certain limit. Therefore, when electrode soldering is performed at a high temperature for a long time, the conventional chip thermistor still has insufficient solder heat resistance.

The thermistor body electrode is formed by applying both ends of the thermistor body to a paste containing a silver-palladium alloy by a dipping method, followed by drying and baking. However, when immersing the thermistor body, even if strict control is performed so that the immersion depth in the paste is constant, variation in the area of the electrode formed on the end surface of the thermistor body is inevitable. As a result, the resistance value of the manufactured chip-type thermistor varies.

In order to improve the solder heat resistance and the solder adhesion described above, it is conceivable to provide a plating layer on the surface of the baked electrode as in the case of the chip type capacitor. However, a ceramic body for the thermistor is used for the capacitor. Unlike the ceramic body, it has conductivity.If plating is performed with this ceramic body exposed, plating adheres to the body surface and the thermistor resistance differs from the expected value.
In addition, the ceramic element is eroded by the plating solution, and the reliability of the thermistor is lowered.

In order to solve this problem, the applicant of the present invention has provided a chip type thermistor in which the surface of a ceramic body other than the portion where the baked electrode layer is in contact is covered with a glass layer and a plating layer is formed on the baked electrode layer. Patent application (Japanese Unexamined Patent Publication No.
50603). This chip type thermistor is manufactured by the following method. First, an insulating glass layer is formed by printing and firing glass paste on both sides of a ceramic sintered sheet. Next, after cutting a sintered sheet having both surfaces covered with a glass layer into a strip shape, a glass paste is printed and fired on the cut surface in the same manner as described above to form a glass layer.
Next, the strip is finely cut in a direction perpendicular to the cut surface to produce a chip. A conductive paste is applied to both ends of the chip so as to cover the cut surface of the chip, and the paste is baked to form a baked electrode layer. Further, a plating layer is formed on the surface of the baked electrode layer to obtain a chip thermistor having a terminal electrode composed of the baked electrode layer and the plated layer. As another conventional solution, when a terminal electrode with a plating layer is formed on a conductive chip-shaped ceramic body, a ceramic material having low conductivity is limitedly used for the ceramic body.

In order to reduce the variation in the resistance value of the above-mentioned chip type thermistor, the present applicant has formed an internal electrode on the end face of the thermistor body, and formed an external electrode so as to cover the internal electrode. (Japanese Patent Application Laid-Open No. 3-250601). This chip type thermistor is manufactured by the following method. First, a paste containing silver, silver-palladium or the like as a main component is applied to the end surface of the thermistor body, dried, and baked to form an encapsulated electrode. A paste containing copper is applied to the end of the thermistor body on which the internal electrode is formed by dipping, dried, and baked to form an external electrode, thereby obtaining a desired chip-type thermistor.

[0007]

However, Japanese Patent Laid-Open Publication No. Hei 3-2
In the production method of No. 50603, the coating of the glass layer needs to be performed in two steps, and an extremely hard sintered sheet must be cut into strips, and the strips must be finely cut into chips. In addition, a great deal of attention must be paid to the handling of the workpiece as the shape of the workpiece changes from the strip shape to the chip shape. For these reasons, there has been a problem that the manufacturing process is complicated and the manufacturing cost is necessarily high.

When a ceramic material having low conductivity is used for the ceramic body, for example, when a Ni-Zn ferrite ceramic material having low conductivity is used for the body of the chip type inductor, this material is Since the magnetic permeability is low, it is necessary to increase the size of the ceramic body in order to obtain desired characteristics, and there is a problem that high-density mounting becomes difficult. In order to avoid this, when a Mn-Zn ferrite-based ceramic material having a high magnetic permeability is used, since this material has high conductivity, plating adheres to the element body surface during the plating process, and the characteristics change. There was a disadvantage.

The chip type thermistor disclosed in Japanese Patent Application Laid-Open No. 3-250601 uses copper as an outer electrode, but still has insufficient heat resistance as compared with a nickel-plated electrode. In addition, since the outer electrode needs to have a high-resistance layer at the part in contact with the thermistor body surface other than the inner electrode,
The outer electrode material was limited, and the firing conditions were complicated.

An object of the present invention is to provide a highly reliable conductive chip type ceramic element which is excellent in solder heat resistance and solder adhesion, has no change in resistance value due to electrode plating, and has high reliability. Another object of the present invention is to provide a conductive chip type ceramic element which can obtain desired characteristics even when an electrode is plated using a highly conductive ceramic material. Another object of the present invention is to provide a conductive chip type ceramic element in which the variation in resistance value is small and the material of the outer electrode layer can be selected widely. Still another object of the present invention is to provide a method for manufacturing a conductive chip type ceramic element suitable for mass production, which makes it possible to manufacture the above excellent conductive chip type ceramic element relatively easily and at low cost.

[0011]

As shown in FIGS. 1 and 2, a first conductive chip-type ceramic element of the present invention comprises a conductive chip-shaped ceramic body 10 and a ceramic chip body 10 of the present invention. A terminal electrode comprising: two terminal electrodes provided on both end surfaces; and an insulating inorganic layer covering the surface of the ceramic body except for a portion where the two terminal electrodes electrically contact each other. Reference numeral 12 denotes a baked electrode layer 16 formed on the surface of the ceramic body 10, a plating layer 18 formed on the surface of the baked electrode layer 16,
19 is an improvement of the conductive chip type ceramic element having a melting point or softening point higher than the firing temperature when the inorganic layer 14 forms the baked electrode layer 16. The characteristic configuration is that the baked electrode layer 16 is formed by baking a conductive paste containing a metal powder and an inorganic binder,
The thickness of the paste is 0.1 to 2 μm, and the inorganic layer in the base portion of the paste reacts and melts with the inorganic binder during the formation of the baked electrode layer 16 and is absorbed by the electrode layer 16 and disappears.

As shown in FIGS. 8 and 9, a second conductive chip type ceramic element according to the present invention comprises a conductive chip-shaped ceramic body 10 and an inner package provided on both end surfaces of the ceramic body 10. The electrode layer 111 and the included electrode layer 11
An insulating inorganic layer 114 covering the entire surface of the ceramic body 10 on which the ceramic layer 1 is formed; outer electrode layers 116 provided on both end surfaces of the ceramic body 10 covering the inorganic layer 114; And a plating layer 118, 119 formed on the surface of the substrate. The characteristic configuration is that the outer electrode layer 116 is formed by baking a conductive paste containing a metal powder and an inorganic binder,
14 has a thickness of 2 to 10 μm and has an outer electrode layer 116.
Has a melting point or softening point higher than the sintering temperature at the time of forming, and a part of the inorganic layer of the base portion of the paste reacts and melts with the inorganic binder at the time of forming the outer electrode layer 116 to form the outer electrode layer 116 It has been absorbed and disappeared.

As shown in FIGS. 1 to 3, the first method for manufacturing a conductive chip type ceramic element of the present invention comprises the steps of mixing a metal oxide powder and a binder to prepare a slurry; A step of forming a green sheet by forming and drying the slurry, a step of punching a chip body 2 from the green sheet, a step of firing the chip body 2 to form a conductive chip-shaped ceramic body 10, Ceramic body 1
0 is coated with an insulating inorganic layer 14 having a thickness of 0.1 to 2 μm on the entire surface of the ceramic element 10, and a conductive material containing a metal powder and an inorganic binder 32 on both end surfaces of the ceramic body 10 coated with the inorganic layer 14. A step of applying the paste 30 and firing the ceramic body 10 to which the paste 30 has been applied at a temperature lower than the melting point or softening point of the inorganic layer 14, and applying the paste to the inorganic binder 32 of the applied paste, Forming the baked electrode layer 16 by extinguishing the inorganic material layer 14 by reacting and melting it;
Forming plating layers 18 and 19 on the surface of the substrate to form a baked electrode layer and a terminal electrode 12 composed of the plating layer.

As shown in FIGS. 8 to 10, a second method of manufacturing a conductive chip-type ceramic element according to the present invention is similar to the first method of manufacturing a conductive chip-shaped ceramic body 10 described above. Forming an internal electrode layer 111 on both end faces of the ceramic body 10, and forming a 2-10 μm thick film on the entire surface of the ceramic body 10 on which the internal electrode layer 111 is formed.
m, a step of coating the insulating inorganic layer 114 with the conductive paste 1 containing the metal powder and the inorganic binder 132 on both surfaces of the ceramic body 10 coated with the inorganic layer 114.
30 and a step of firing the ceramic body 10 to which the paste 130 has been applied at a temperature lower than the melting point or softening point of the inorganic layer 114, and applying the inorganic layer at the base portion of the paste to the inorganic binder 132 of the applied paste. Is formed by reacting and melting a part of the outer electrode layer to form an outer electrode layer 116, and a step of forming plating layers 118 and 119 on the surface of the outer electrode layer 116.

Hereinafter, the present invention will be described in detail. (I) Production of First Conductive Chip Ceramic Element (a) Production of Chip Ceramic Element The chip ceramic element of the present invention is produced by the following method. First, a metal oxide powder is collected according to the use of the ceramic element. For example, if the thermistor is Mn, F
e, a metal oxide powder such as Co, Ni, Cu, Al
In the case of a varistor, oxide powder of a metal such as Ti, Ce, Ca, Sb, or Nb is used.
One or more kinds of oxide powders of metals such as Co, Ni, Zn, and Mn are collected and mixed. When mixing two or more, each metal oxide is weighed so as to have a predetermined metal atomic ratio. After calcining and pulverizing this mixture, an organic binder and a solvent are added and kneaded to prepare a slurry. Next, the slurry is dried by a doctor blade method or the like to form a green sheet. Figure 3 from this green sheet
The chip body 2 shown in FIG.
A chip-shaped ceramic body 10 shown in FIG.

(B) Coating of Insulating Inorganic Layer on Ceramic Body The obtained ceramic body 10 has a thickness of 0.1 to
A 2 μm insulating inorganic material layer is coated (FIG. 3C).
When the thickness is more than 2 μm, the inorganic layer melted during the formation of the electrode layer described later is not completely absorbed in the electrode layer and remains at the interface between the electrode layer and the ceramic body, so that the electrode has sufficient conductivity with respect to the ceramic body. I can't get it. On the other hand, when the thickness is less than 0.1 μm, the function of protecting the ceramic body after plating and after plating is inferior. This insulating inorganic layer 14 (FIGS. 1 and 2) is exemplified by SiO 2
₂ film, or 50% by weight or more of SiO ₂ and the balance being Al ₂ O ₃ ,
A thin film composed of one or more oxides of MgO, ZrO ₂ or TiO ₂ , or SiO ₂ , B ₂ O ₃ , N
Examples of the thin film include a glass mainly containing one or more oxides of a ₂ O, PbO, ZnO, and BaO. The inorganic layer 14 needs to have a melting point or a softening point higher than a firing temperature at the time of forming a firing electrode layer described later. For example, when baking an Ag paste, the baking temperature is 600 to 850 ° C., and therefore, a paste having a melting point or softening point higher than this temperature is selected. The reason for this is that if the melting point or softening point is significantly lower than the baking temperature of the paste, the inorganic layer will float on the electrode surface during baking of the paste, or the ceramic bodies will stick together or the body and the firing jig will occur, and the yield will increase. Is likely to decrease. The inorganic layer 14 is not particularly limited as long as it has plating resistance other than this requirement and has a property of reacting and melting with an inorganic binder contained in a conductive paste described later. May also be non-crystalline.

The inorganic layer is coated on the ceramic body by a physical vapor deposition method (PVD method) such as a vacuum vapor deposition method, a sputtering method, or an ion plating method, or a chemical vapor deposition method (C
VD method). Among them, the sputtering method is preferable because it is suitable for mass production. For mass production by this method, as shown in FIG. 4, a stainless steel basket 22 rotatable about a horizontal shaft 20 is prepared, and a number of ceramic elements 10 are stored therein. The basket 22 is placed in a sputtering device (not shown). A target 24 for obtaining a desired inorganic layer is mounted in the apparatus. For example, if the inorganic layer is a SiO ₂ film, quartz glass is used, and SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO _{2
2, B 2 O 3, Na} 2 O, PbO, ZnO, if a composite oxide film of BaO or the like, these are formed into a disk shape by powder metallurgy or, or composite glass of the cooled molten disc-shaped To use. When sputtering is performed while swinging the basket 22 about the horizontal axis 20, the target material beaten from the target 24 condenses on the entire surface of the ceramic body 10, and the inorganic layer 14 made of the target material is formed.

(C) Formation of Baked Electrode Layer As shown in FIG. 3D, a conductive paste 30 containing a metal powder and an inorganic binder is provided on both end surfaces of the ceramic body 10 covered with the insulating inorganic layer 14. Is applied. For this application, a dipping method in which both ends of the ceramic body are immersed in a conductive paste is preferable. As an example of metal powder,
Noble metals such as Ag, Au, Pd, and Pt, or powders obtained by mixing these are mentioned. As an example of an inorganic binder, Si
One of O ₂ , B ₂ O ₃ , Na ₂ O, PbO, ZnO or BaO
Glass fine particles, such as borosilicate glass, zinc borate glass, cadmium borate glass, and lead zinc silicate glass, mainly containing a kind or two or more kinds of oxides are exemplified. As shown in FIG. 5, the applied conductive paste 30
An inorganic binder 32 is uniformly dispersed in the paste.
It is necessary to have the property of reacting with the inorganic layer 14 that comes into contact with the inorganic layer 14 and melting the inorganic layer 14 as shown in FIG.

(D) Formation of plating layer A plating layer is formed on the surface of the baked electrode layer. This plating layer is preferably formed into a double structure by forming a Ni plating layer 18 as shown in FIG. 3F and then forming an Sn plating layer 19 as shown in FIG. 3G. Ni plating layer 1
Numeral 8 improves the solder heat resistance, prevents electrode erosion of the baked electrode layer by solder, and Sn plating layer 19 improves solder adhesion. The terminal electrode 12 is formed by the baked electrode layer 16 and the plating layers 18 and 19.

(II) Production of Second Conductive Chip-Type Ceramic Element (a) Production of Chip-shaped Ceramic Element The element is produced in the same manner as the above-mentioned (I) (a) Chip-shaped Ceramic Element.

(B) Formation of the encapsulated electrode layer As shown in FIG. 10C, a paste containing silver or a silver-palladium alloy is applied to both end surfaces of the ceramic body, dried and baked to form the encapsulated electrode. The layer 111 is formed. The material of the encapsulating electrode layer 111 is not limited to silver or a silver-palladium alloy as long as the material maintains conductivity with the ceramic body 10. In addition, gold, platinum, or a metal material containing these as a main component May be. To apply the paste, a number of ceramic bodies are aligned so that each end face is on the upper surface, and then the paste is screen-printed on each end face.

Specifically, as shown in FIG. 11A, a large number of holding holes 34a for holding the ceramic body 10 are provided.
A holding plate 34 made of an elastic material on which is formed is used. The loading plate 35 having the introduction holes 35a corresponding to the holding holes 34a is superimposed on the holding plate 34, and the lower side of the plate 34 is set to a negative pressure by a vacuum pump or the like to put the ceramic body 10 into each holding hole 34a (FIG. 11
(B)). The introduction hole 35a is formed wide so that the end face of the ceramic body 10 is on the upper surface. After releasing the negative pressure state, the pushing tool 3 provided with the pushing pins 36a by the number of holes.
6, each pin 36a is inserted from the upper side of the plate 34 into each holding hole 34a by a predetermined length, and the ceramic element 1
0 is projected from the lower surface of the plate 34. In this state, the holding plate 34 is turned upside down, and screen printing is performed on the end surface of the ceramic body 10 having a uniform height as shown in FIG. In FIG. 11C, reference numeral 37 denotes a screen, 38 denotes a squeegee, and 39 denotes a silver paste.

(C) Coating of Insulating Inorganic Material Layer on Ceramic Element The ceramic element 10 on which the encapsulating electrode layer 111 is formed is coated on the entire surface with an insulating inorganic material layer 114 having a thickness of 2 to 10 μm (FIG. 10 (d)). When the thickness is larger than 10 μm, the inorganic layer remains at the interface between the outer electrode layer and the inner electrode layer as an insulating film when the outer electrode layer described later is formed, so that the outer electrode layer and the inner electrode layer do not conduct. If the thickness is less than 2 μm, an end portion of the ceramic body of the outer electrode layer, which will be described later, is electrically connected to the ceramic body, so that the resistance value of the chip-type ceramic element varies. As an example of this insulating inorganic layer 114 (FIGS. 8 and 9), S
iO ₂ film, or 50% by weight or more of SiO ₂ and the balance being Al ₂
A thin film composed of one or more oxides of O ₃ , MgO, ZrO ₂ or TiO ₂ , or SiO ₂ , B ₂ O
_3, Na ₂ O, PbO, include thin films made of glass whose main component is one or more oxides of ZnO or BaO. The inorganic layer 114 needs to have a melting point or softening point higher than the firing temperature when forming the outer electrode layer for the same reason as the inorganic layer 14 described above. The inorganic layer 114 is not particularly limited as long as it has plating resistance other than this requirement and has a property of reacting and melting with an inorganic binder contained in a conductive paste described later, and is crystalline. May also be non-crystalline.

The coating of the inorganic layer on the ceramic body is performed by a physical vapor deposition method (PVD method) or a chemical vapor deposition method (CVD method) as in the first method. Among them, the sputtering method shown in FIG. 4 is preferable because it is suitable for mass production. As shown in FIG. 4, when sputtering is performed while swinging the basket 22 about the horizontal axis 20, the target material beaten out of the target 24 condenses on the entire surface of the ceramic body 10, and the inorganic material made of the target material Layer 114
Is formed.

(D) Formation of Envelope Electrode Layer As shown in FIG. 10 (e), a conductive paste 130 containing a metal powder and an inorganic binder is applied to both ends of the ceramic body 10 covered with the insulating inorganic layer 114. Apply. For this application, a dipping method in which both ends of the ceramic body are immersed in a conductive paste is preferable. Examples of the metal powder include noble metals such as Ag, Au, Pd, and Pt, and powders obtained by mixing these. As an example of an inorganic binder,
SiO ₂ , B ₂ O ₃ , Na ₂ O, PbO, ZnO or BaO
And glass fine particles such as borosilicate glass, zinc borate glass, cadmium borate glass, and lead zinc silicate glass mainly containing one or more oxides of the above. As shown in FIG. 12, an inorganic binder 132 is uniformly dispersed in the applied conductive paste 130, and the inorganic binder 132 and the inorganic layer 114 contacting the paste 130 when the conductive paste is baked. As shown in FIG. 13, it is necessary to have a property of causing a part of the inorganic layer 114 to melt and annihilate as shown in FIG. The conductive paste 130 produces an outer electrode layer 116 by baking, and the outer electrode layer 116
14 disappears, the encapsulation electrode layer 111
Electrically connected to

(E) Formation of Plating Layer A plating layer is formed on the surface of the outer electrode layer 116. This plating layer is a Ni plating layer 11 as shown in FIG.
After forming No. 8, it is preferable to form an Sn plating layer 119 as shown in FIG. The functions of the plating layers 118 and 119 are the same as those of the plating layers 18 and 19. Inner electrode layer 111, outer electrode layer 11
6 and the plating layers 118 and 119, the terminal electrode 112.
(FIGS. 8 and 9) are formed.

[0027]

In the production of the first conductive chip-type ceramic element, the ceramic body coated with the conductive paste is fired at a temperature lower than the melting point or softening point of the inorganic layer.
As shown in FIG. 6E and FIG. 6, a baked electrode layer 16 is formed. That is, at the time of this baking, the inorganic binder 32 uniformly dispersed in the paste is applied to the inorganic layer 14 under the paste.
And melts it. The inorganic material of the fluidized layer 14 penetrates into pores in the electrode layer 16 formed when the metal is sintered. The ultra-thin inorganic layer 14 is completely absorbed into the pores during the firing process and disappears from the end of the ceramic body.
As a result, the baked electrode layer 16 and the ceramic body 10 are directly adhered to each other and are electrically connected to each other. On the other hand, even when the paste is baked, the portion of the inorganic material layer 14 on which the conductive paste is not applied has a melting point or softening point higher than the sintering temperature, so that no change occurs on the surface of the ceramic body 10 without any change. Remains and retains its insulation protection function.

In the manufacture of the second conductive chip type ceramic element, when the ceramic body coated with the conductive paste for the outer electrode layer is fired at a temperature lower than the melting point or softening point of the inorganic layer, FIG. And, as shown in FIG. 13, an outer electrode layer 116 is formed. That is, at the time of this baking, the inorganic binder 132 uniformly dispersed in the paste is applied to the inorganic material layer 1.
It reacts with part of 14 to melt it. The fluidized inorganic material of the inorganic material layer 114 penetrates into pores in the outer electrode layer 116 formed when the metal is sintered. Since the thickness of the inorganic layer 114 is set to 2 to 10 μm, the inorganic layer 11
Part of 4 is absorbed in the pores during the firing process and partially disappears from the surface of the encapsulating electrode layer 111. As a result, the outer electrode layer 116 and the inner electrode layer 111 are directly adhered to each other through the disappeared portion of the inorganic layer 114, and are electrically connected to each other. Since the inner electrode layer 111 is formed so as to maintain conductivity with the ceramic body 10, the outer electrode layer 11
6 and the ceramic body 10 are electrically connected.

The ceramic body 10 and the outer electrode layer 1
In the part of the inorganic layer 114 where the inner electrode layer 111 does not exist, the molten inorganic layer 114 is partially absorbed into the outer electrode layer 116, but the inorganic layer 114 is not.
4 has a thickness of 2 μm or more, most of it remains on the ceramic body 10. Therefore, the ceramic body 10 and the outer electrode layer 116 are partially joined. However, since the bonding is partial, the conductivity between the outer electrode layer 116 and the ceramic body 10 is negligibly smaller than the conductivity at the portion where the inner electrode layer 111 is interposed, and the current is reduced. , Internal electrode layer 111, ceramic body 10
Flow through On the other hand, even when the paste is baked, the portion of the inorganic layer 114 to which the conductive paste for the outer electrode layer is not applied is not changed at all because the melting point or softening point of the inorganic layer is higher than the firing temperature. It remains on the surface of the body 10 and retains its insulation protection function.

[0030]

As described above, in the conventional manufacturing method, the number of steps is large and complicated. However, according to the first and second manufacturing methods of the present invention, the number of steps is relatively easy with few steps. Since the terminal electrodes of the conductive chip type ceramic element can be formed, it is suitable for mass production and the electrode formation cost is reduced. Further, in the conductive chip type ceramic element of the present invention, the ceramic body is covered with an insulating inorganic layer except for a portion where the electrode is in contact, and the ceramic body is protected by this inorganic layer. Also, there is no change in characteristics due to erosion of the plating solution on the element body or adhesion of the plating. By forming a plating layer on the surface of the baked electrode layer, an effect excellent in solder heat resistance and solder adhesion can be obtained. In particular, the conductive chip type ceramic element provided with the inner electrode layer has an advantage that the variation of the resistance value is small and the material of the outer electrode layer can be selected widely.

[0031]

EXAMPLES Next, the present invention will be described based on examples to show specific embodiments of the present invention. The embodiments described below do not limit the technical scope of the present invention. Example 1 A chip thermistor shown in FIGS. 1 and 2 was produced as a conductive chip ceramic element by the following method. First, commercially available manganese carbonate, nickel carbonate, and cobalt carbonate were used as starting materials, and these were used as MnO ₂ : Ni
Each was weighed at a metal atomic ratio of 3: 1: 2 in terms of O: CoO. The weighed product was uniformly mixed by a ball mill for 16 hours and then dehydrated and dried. The mixture is then 900
The resultant was calcined at a temperature of 2 ° C. for 2 hours. A binder of 6% by weight of polyvinyl butyral, 30% by weight of ethanol and 30% by weight of butanol was added to 100% by weight of the pulverized material, and the mixture was uniformly mixed to prepare a slurry. The slurry was dried by a doctor blade method to form a green sheet having a thickness of 0.80 mm. 2.34mm x 1.48m from this sheet
m chip size, punched at 1200 ° C under atmospheric pressure
For 4 hours to obtain a sintered body having a length of 1.9 mm, a width of 1.2 mm and a thickness of 0.65 mm. This sintered body is shown in FIG.
The ceramic body 10 for a thermistor shown in FIG.
_An insulating inorganic layer composed of _two films was formed. That is, a stainless steel basket 22 containing a large number of ceramic elements 10 is set in a sputtering apparatus using quartz glass as a target 24, and sputtering is performed while swinging the basket 22. S over the entire surface
An iO ₂ film was formed with a thickness of 2 μm (FIG. 3C).

The terminal electrodes 12 were provided at both ends of the ceramic body 10 by the following method. The terminal electrode 12 includes a baked electrode layer 16, a Ni plating layer 18, and a Sn plating layer 19. First, a conductive paste was applied to both end surfaces of the ceramic body on which the inorganic layer was formed by dipping (FIG. 3D). The conductive paste is a commercially available silver paste (JPN-1176 manufactured by DuPont),
It is composed of Ag powder, glass fine particles composed of SiO ₂ , TiO ₂ , B ₂ O ₃ , Na ₂ O and K ₂ O, and an organic vehicle. After drying the ceramic body coated with the conductive paste under atmospheric pressure, the temperature is raised to 820 ° C. at a rate of 30 ° C./min, held there for 10 minutes, and lowered to room temperature at a rate of 30 ° C./min. A baked electrode layer 16 made of Ag was obtained (FIG. 3).
(E)). Next, a Ni plating layer 18 having a thickness of 2 to 3 μm was formed on the surface of the electrode layer 16 by electrolytic barrel plating, and a Sn plating layer 19 having a thickness of 1 to 2 μm was subsequently formed.

Comparative Example 1 A chip-type thermistor with a plating layer was produced in the same manner as in Example 1 except that the inorganic layer 14 was not formed. <Comparative Example 2> Without providing the Ni plating layer and the Sn plating layer,
850 conductive paste containing 80% Ag and 20% Pd
The terminal electrode was constituted only by a baked electrode layer made of silver-palladium by baking at ℃.

<Comparison Test and Results>-Plating adherence to element body The surface of each ceramic element body of the chip-type thermistor of Example 1 after the plating treatment and the chip-type thermistor of Comparative Example 1 were examined with an optical microscope. In the thermistor of Example 1, plating adhered to the surface of the ceramic body as well as the surface of the electrode, whereas in the thermistor of Example 1, the plating layer was formed only on the surface of the electrode layer. Solder adhesion Thermistors of Example 1 and Comparative Example 2 were 300
Each sample was prepared and immersed in a eutectic solder (H60-A) containing Ag melted at a temperature of 230 ° C. for 4 seconds with tweezers sandwiching the sample, and the solder adhesion area of the terminal electrode was examined with an optical microscope. . Table 1 shows the results. Solder heat resistance Thermistor of Example 1 and Comparative Example 2 were replaced with 300.
Each sample was prepared and immersed in a eutectic solder (H60-A) bath containing Ag melted at a temperature of 350 ° C. with tweezers for 30 seconds with tweezers, and the disappearance of the terminal electrode was examined with an optical microscope. Table 1 shows the results. As is clear from Table 1, the thermistor of Example 1 was superior to Comparative Example 2 in solder adhesion and solder heat resistance.

[0035]

[Table 1]

Example 2 A laminated chip type varistor made of TiO ₂ shown in FIG. 7 was produced as a conductive chip type ceramic element by the following method. First, as an additive to commercially available titanium dioxide, borosilicate glass fine particles, C
e, Ca, Nb and Sb metal oxides were mixed in small amounts. These mixtures were uniformly mixed by a ball mill for 16 hours and then dehydrated and dried. Next, this mixture was calcined in the same manner as in Example 1, and the calcined product was pulverized. An organic binder was added to the pulverized material, and the mixture was uniformly mixed to prepare a slurry. The slurry is dried by a doctor blade method to a thickness of 30 mm.
A green sheet of μm was formed. 12 from this sheet
After punching into a size of 0 mm × 120 mm and inspecting the film thickness, a Pt paste was printed and dried on one surface of the sheet to form an internal electrode 43. Next, green sheets of the same size, on which no internal electrodes were printed, were sequentially laminated on the upper and lower surfaces of the sheet on which the internal electrodes had been formed as a protective film, and were pressed under heating to form a laminate. This laminate is cut into chips and separated, baked at 1300 ° C. under atmospheric pressure, and 2.1 m long
m, a width of 1.3 mm and a thickness of 0.7 mm were obtained. This sintered body was coated with a thickness of 2
After forming an insulating inorganic layer 44 made of a ₂ μm SiO ₂ film and applying a conductive paste to both end surfaces of the sintered ceramic body 40, a baked electrode layer 46 made of Ag is formed.
I got Thereafter, a Ni plating layer 48 having a thickness of 2 to 3 μm is formed on the surface of the electrode layer 46 by electrolytic barrel plating in the same manner as in Example 1.
Then, a Sn plating layer 49 having a thickness of 1 to 2 μm was formed. Thus, the terminal electrode 42 including the baked electrode layer 46, the Ni plating layer 48, and the Sn plating layer 49 was formed.

Comparative Example 3 A laminated chip varistor having a plating layer was produced in the same manner as in Example 2 except that the inorganic layer 44 was not formed. When the surface of each ceramic body of the chip-type varistor of Example 2 and the chip-type varistor of Comparative Example 3 after the plating treatment was examined with an optical microscope, the thermistor of Comparative Example 3 was plated not only on the electrode surface but also on the ceramic body surface. However, in the varistor of Example 2, the plating layer was formed only on the surface of the electrode layer.

Example 3 A chip thermistor shown in FIGS. 8 and 9 was produced as a conductive chip ceramic element by the following method. In the same manner as in Example 1, first, a sintered body having a length of 1.9 mm, a width of 1.2 mm, and a thickness of 0.65 mm was obtained. This sintered body was used as a ceramic body 10 for a thermistor shown in FIG.
0 is aligned using the loading plate 35 and the holding plate 34 shown in FIGS. 11A to 11C so that each end face is the upper surface, and then a silver paste is applied to each end face by a screen printing method. And dried. After drying, baking was performed at 800 ° C. under atmospheric pressure to form the encapsulating electrode layer 111 (FIG. 10C). Next, an insulating inorganic layer 114 made of a SiO ₂ film was formed on the entire surface of the ceramic body 10 on which the encapsulating electrode layer 111 was formed in the same manner as in Example 1 using the sputtering apparatus shown in FIG.
(D)).

Further, in the same manner as the method of forming the baked electrode layer 16, the Ni plating layer 18, and the Sn plating layer 19 of the first embodiment, outer ends are wrapped around both ends of the ceramic body 10 whose entire surface is covered with the SiO ₂ film 114. Electrode layer 116 and Ni plating layer 11
8 and a Sn plating layer 119 were sequentially formed (FIG. 10E).
To FIG. 10 (h)). External electrode layer 116 and Ni plating layer 1
18 and the Sn plating layer 119 were formed such that the respective configurations were the same as those of the baked electrode layer 16, the Ni plating layer 18, and the Sn plating layer 19 of the first embodiment.

Comparative Example 4 A chip-type thermistor with a plating layer was manufactured in the same manner as in Example 3 except that the internal electrode layer 111 and the inorganic layer 114 were not formed. <Comparative Example 5> Internal electrode layer 111, inorganic layer 114, Ni
A chip-type thermistor on which an outer electrode layer 116 was formed was manufactured in the same manner as in Example 3 except that the plating layer 118 and the Sn plating layer 119 were not formed.

<Comparison Tests and Results>-Plating adherence to elementary bodies The thermistor element surfaces of the chip-type thermistor of Example 3 and the chip-type thermistor of Comparative Example 4 after plating were examined with an optical microscope. In the thermistor of Example 4, plating adhered to the surface of the thermistor body as well as the surface of the electrode, whereas in the thermistor of Example 3, a plating layer was formed only on the surface of the electrode layer. -Variation in resistance value The thermistor of Example 3 and the thermistor of Comparative Example 5 were 100
Each was prepared, the resistance value was measured, and the variation of the resistance value was calculated from the average value and the standard deviation. As a result, the variation of the resistance value (standard deviation / average resistance value) of the thermistor of Example 3 was 1.04%, whereas that of Comparative Example 5 was 3.27%. 3 had a smaller variation in resistance value than Comparative Example 5.

[Brief description of the drawings]

FIG. 1 is a cutaway perspective view of a main part of a first chip-type ceramic element of the present invention.

FIG. 2 is a central sectional view thereof.

FIG. 3 is a perspective view of the element body in a process of producing a chip-type ceramic element from the first conductive chip-shaped ceramic element of the present invention.

FIG. 4 is a schematic perspective view of a sputtering apparatus for coating the surface of the ceramic body with an insulating inorganic layer.

FIG. 5 is an enlarged sectional view of a main part in a state where a conductive paste is applied to the ceramic body.

FIG. 6 is an enlarged sectional view of a main part in a state where the conductive paste is baked.

FIG. 7 is a sectional view of a multilayer chip type varistor according to an embodiment of the present invention.

FIG. 8 is a cutaway perspective view of a main part of a second chip-type ceramic element of the present invention.

FIG. 9 is a central sectional view thereof.

FIG. 10 is a perspective view of the element body in a process of manufacturing a chip-type ceramic element from the second conductive chip-shaped ceramic element of the present invention.

FIG. 11 is a cross-sectional view of a holding plate of the ceramic body, showing a situation where a silver paste for an internal electrode layer is applied to the end surface of the ceramic body.

FIG. 12 is an enlarged sectional view of a main part in a state where a conductive paste for an outer electrode layer is applied to the ceramic body.

FIG. 13 is an enlarged cross-sectional view of a main part in a state where the conductive paste is baked to form an outer electrode layer.

[Explanation of symbols]

 2 Chip body 10,40 Ceramic body 12,42,112 Terminal electrode 14,44,114 Insulating inorganic layer 16,46 Baking electrode layer 18,48,118 Ni plating layer 19,49,119 Sn plating layer 30,130 Conductive paste 32, 132 inorganic binder 111 inner electrode layer 116 outer electrode layer

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masami Koshimura 2270 Yokoze, Yokoze-cho, Chichibu-gun, Saitama Prefecture Mitsubishi Materials Corporation Ceramics Research Laboratory (56) References JP-A-3-173402 (JP, A) JP-A Heihei 3-250603 (JP, A) JP-A-3-270102 (JP, A) JP-A-3-250601 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01C 7/02 -7/22

Claims (10)

(57) [Claims] A conductive chip-shaped ceramic body (10);
Two terminal electrodes (12) provided on both end surfaces of the ceramic body (10) and a surface of the ceramic body (10) except for a portion where the two terminal electrodes are in electrical contact with each other. The terminal electrode (12) is formed on the surface of the ceramic body (10), and the surface of the baked electrode layer (16) is provided. In the conductive chip type ceramic element having a melting point or softening point higher than the firing temperature at the time of forming the baked electrode layer, the plating layer (18, 19) and the inorganic layer (14), The baking electrode layer (16) is formed by baking a conductive paste containing a metal powder and an inorganic binder, and the inorganic layer (14) has a thickness of 0.1 to 2 μm, and a base portion of the paste. The inorganic layer reacts and melts with the inorganic binder at the time of forming the baked electrode layer (16). A conductive chip-type ceramic element, which has been absorbed and disappeared by the electrode layer (16). 2. The insulating inorganic layer (14) is made of SiO ₂ or 50.
% By weight or more of SiO ₂ and the balance being Al ₂ O ₃ , MgO, Zr
It is composed of one or more oxides of O ₂ or TiO ₂ , and the inorganic binder is SiO ₂ , B ₂ O ₃ , Na ₂ O, Pb
2. The conductive chip-type ceramic element according to claim 1, wherein the conductive chip-type ceramic element is composed of glass fine particles containing one or more oxides of O, ZnO or BaO as a main component. 3. The insulating inorganic layer (14) is made of SiO ₂ , B
It is made of a glass mainly containing one or more oxides of ₂ O ₃ , Na ₂ O, PbO, ZnO or BaO, and the inorganic binder is SiO ₂ , B ₂ O ₃ , Na ₂ O, PbO. ,
2. The conductive chip type ceramic element according to claim 1, wherein the conductive chip type ceramic element is constituted by glass fine particles containing one or more oxides of ZnO or BaO as a main component. 4. A conductive chip-shaped ceramic body (10),
An internal electrode layer (111) provided on both end surfaces of the ceramic element (10), and an insulating inorganic layer (114) covering the entire surface of the ceramic element (10) on which the internal electrode layer (111) is formed. )When,
An outer electrode layer (116) provided on both end surfaces of the ceramic body (10) coated with the inorganic layer, and the outer electrode layer (11
6) a conductive chip type ceramic element comprising a plating layer (118, 119) formed on the surface, wherein the outer electrode layer (116) is formed by baking a conductive paste containing a metal powder and an inorganic binder. The inorganic layer (114) has a thickness of 2 to 10 μm, has a higher melting point or softening point than the firing temperature at the time of forming the outer electrode layer (116), and the base portion of the paste A conductive chip type ceramic element, wherein a part of the inorganic layer reacts and melts with the inorganic binder when the outer electrode layer (116) is formed and is absorbed and disappeared by the outer electrode layer (116). 5. The insulating inorganic layer (114) is made of SiO._TwoOr 50
% By weight or more of SiO _TwoAnd the balance is Al_TwoO_Three, MgO, Zr
O_TwoOr TiO_TwoConsists of one or more oxides of
And the inorganic binder is SiO_Two, B_TwoO_Three, Na_TwoO, Pb
One or more oxides of O, ZnO or BaO
5. The method according to claim 4, wherein said glass fine particles are used as a component.
Conductive chip type ceramic element. 6. The insulating inorganic layer (114) is made of SiO ₂ , B
It is made of a glass mainly containing one or more oxides of ₂ O ₃ , Na ₂ O, PbO, ZnO or BaO, and the inorganic binder is SiO ₂ , B ₂ O ₃ , Na ₂ O, PbO. ,
5. The conductive chip type ceramic element according to claim 4, wherein the element is made of glass fine particles containing one or more oxides of ZnO or BaO as a main component. 7. A step of preparing a slurry by mixing a metal oxide powder and a binder; a step of forming a green sheet by forming a film of the slurry; and forming a chip body (2) from the green sheet. A step of punching; a step of firing the chip body (2) to form a conductive chip-shaped ceramic body (10); and an insulating layer having a thickness of 0.1 to 2 μm on the entire surface of the ceramic body (10). A step of coating the inorganic layer (14), and applying a conductive paste (30) containing a metal powder and an inorganic binder (32) to both end surfaces of the ceramic body (10) coated with the inorganic layer (14). And firing the ceramic body (10) coated with the paste (30) at a temperature lower than the melting point or softening point of the inorganic layer (14),
A step of forming the baked electrode layer (16) by reacting and melting the inorganic layer (14) of the base part of the paste on the inorganic binder (32) of the applied paste to form a baked electrode layer (16); 16) forming a plating layer (18, 19) on the surface of the terminal electrode (12) comprising the baked electrode layer and the plating layer
Forming a conductive chip-type ceramic element. 8. An insulating inorganic layer on a ceramic body (10)
The method for producing a conductive chip type ceramic element according to claim 7, wherein the coating of (14) is performed by a physical vapor deposition method. 9. A step of preparing a slurry by mixing a metal oxide powder and a binder; a step of forming a film by drying the slurry to form a green sheet; and forming a chip body (2) from the green sheet. A step of punching; a step of firing the chip body (2) to form a conductive chip-shaped ceramic body (10); and forming an internal electrode layer (111) on both end surfaces of the ceramic body (10). A step, and the ceramic body on which the internal electrode layer (111) is formed.
An insulating inorganic layer (114) having a thickness of 2 to 10 μm on the entire surface of (10)
Coating a conductive paste (130) containing metal powder and an inorganic binder (132) on both surfaces of the ceramic body (10) coated with the inorganic layer (114), The ceramic element (10) coated with the paste (130) is fired at a temperature lower than the melting point or softening point of the inorganic layer (114), and the inorganic binder (132) of the applied paste is coated with a base portion of the paste. A step of forming an outer electrode layer (116) by eliminating a part of the inorganic layer by reacting and melting, and a step of forming a plating layer (118, 119) on the surface of the outer electrode layer (116). Of manufacturing a chip-type ceramic element. 10. The method for manufacturing a conductive chip type ceramic element according to claim 9, wherein the coating of the insulating inorganic layer (114) on the ceramic body (10) is performed by a physical vapor deposition method.