JP3297531B2 - Conductive paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a conductive paste.
More specifically, the present invention relates to a conductive paste used for terminal electrodes and the like of a laminated ceramic capacitor.

[0002]

2. Description of the Related Art Conductive pastes are widely used for forming terminal electrodes and internal electrodes of, for example, laminated ceramic (ceramic) capacitors, and conductive films such as conductive circuits on substrates such as glass and ceramics. Is applied by a method such as printing or the like, dried, and baked by a method such as baking to form a conductive film.

[0003] Such conductive pastes include silver (Ag),
Any one of gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), copper (Cu), zinc (Zn), or a mixture thereof, and several types of glass frit It is dispersed in an organic vehicle, and the glass frit is made of lead silicate glass, lead borosilicate glass, bismuth borosilicate glass, zinc borosilicate glass, cadmium borate glass, or the like. I have.

When a terminal electrode of a laminated ceramic capacitor is formed by using a conductive paste, a conductive film formed by the conductive paste has characteristics such as the appearance of the film and the capacitor body in addition to conductivity. It is required that the adhesive strength to the dielectric ceramic to be formed and the plating resistance when the film is subjected to electrolytic plating be good. It is also required that the electrode film after firing has no voids and has good sealing properties with respect to a plating solution.

Conventionally, a conductive paste for forming terminal electrodes of a laminated ceramic capacitor has a fine powder of Ag and 50% of PbO.
80 wt%, B ₂ O ₃ is 10 to 20 wt%, SiO ₂ is 5
A silver paste obtained by dispersing a low melting point lead borosilicate glass frit having a composition of 15% by weight and ZnO of 1 to 10% by weight in an organic vehicle has been used.

JP-A-58-11565 discloses that a noble metal powder and 1 to 30% by weight of a zinc borosilicate glass frit containing an alkali metal and an alkaline earth metal are dispersed in an inert organic vehicle. A conductive paste formed by the above method has been proposed. According to the conductive paste disclosed in the publication, the surface of a conductive film formed by baking the conductive paste is not deteriorated even if a metal film treatment is performed by an electrolytic plating method, and the adhesive strength is not impaired at all.

[0007]

However, the terminal electrode formed of the above-mentioned conventional silver paste has a high PbO content in the glass frit, and therefore has an insufficient adhesive force with the dielectric porcelain, so that the terminal electrode after baking is not obtained. If the electrode film has a bad appearance such as spherical swelling, floating or peeling of the film, or electrolytic plating, the plating solution passes between the internal electrode of the laminated ceramic capacitor and the dielectric ceramic through the terminal electrode. There are problems such as intrusion of the conductive ions and intrusion of characteristics such as the Q value of the porcelain capacitor. In addition, a phenomenon has been observed in which glass frit segregates and floats on the surface of the electrode film in a layered manner, which deteriorates solder wettability and heat resistance when soldering is performed on the electrode film, or causes glass frit or precious metal There is also a problem that solder cracks occur in which (silver) melts into the solder.

Further, even with a conductive paste having a composition proposed in Japanese Patent Application Laid-Open No. 58-11565, the ZnO component contained in the glass frit oozes out by baking, so that an electrode formed with the conductive paste is used. There was a problem that the film changed color after plating.

SUMMARY OF THE INVENTION The present invention has been completed to solve the problems in view of the above circumstances, and has as its object the purpose of having a good external appearance, adhesion to a substrate such as a dielectric ceramic, and plating resistance to electrolytic plating. An object of the present invention is to provide a conductive paste from which a conductive film having excellent properties can be obtained.

Another object of the present invention is to provide, when used for forming electrodes of a laminated ceramic capacitor, a good external appearance, excellent adhesion to a substrate such as a dielectric ceramic, and excellent plating resistance to electrolytic plating. Another object of the present invention is to provide a conductive paste which is excellent in solder wettability and heat resistance, has no voids in the electrode film, and can provide an electrode film having a good sealing property to a plating solution.

[0011]

The conductive paste of the present invention comprises a metal powder, a lead silicate glass frit having a softening point of 3 to 6% by weight based on the metal powder, and a silicate glass frit having a softening point of 650 ° C. or higher.
It is characterized in that a 6% by weight zinc borosilicate glass frit having a softening point of 620 ° C or less and a 2 to 15% by weight lead borosilicate glass frit having a softening point of 620 ° C or less are dispersed in an organic vehicle. It is assumed that.

In the conductive paste of the present invention, in the conductive paste having the above composition, the lead silicate glass frit is made of PbO and SiO ₂ , Na ₂ O, K ₂ O, Al
_At least one of ₂ O _{3, wherein} the zinc borosilicate glass frit is ZnO and B ₂ O ₃ , SiO ₂ ,
Na ₂ O, K ₂ O consists, lead borosilicate glass frit PbO and _{B 2 O 3, SiO 2,} TiO 2, Cu
It is characterized by being composed of O and CrO.

[0013]

The conductive paste of the present invention has the following composition:
A lead silicate glass frit having a softening point of 650 ° C or higher (hereinafter, referred to as a high softening point); a zinc borosilicate glass frit having a softening point of 620 ° C or lower (hereinafter, referred to as a low softening point);
620 ° C containing TiO ₂ , CuO and CrO
A ternary glass frit comprising the following (hereinafter also referred to as low softening point) lead borosilicate glass frit:
By mixing with a metal powder at a predetermined ratio, a conductive paste having high adhesion to a base such as a dielectric porcelain and a conductive film having good plating resistance can be obtained.

The softening point means a temperature at which an amorphous substance such as glass becomes soft. Amorphous substances, unlike crystalline solids, often do not have a clear melting temperature,
At low temperatures, it undergoes elastic deformation in response to external forces, but strictly speaking, not only elastic deformation but also permanent deformation,
That is, plastic deformation is performed. The ratio of plastic flow velocity to stress (the reciprocal of viscosity) of an amorphous material is extremely small at low temperatures, but increases sharply with increasing temperature, and has remarkable fluidity when passing through a relatively narrow temperature range. It becomes a soft state. In this state, the viscosity is actually 10 ¹¹ to 10 ¹²
At a temperature at which P (poise) is reached, a state in which flow is observed within a time period of about 1 to 10 seconds. The temperature at which the amorphous substance softens in this sense is called the softening point. On the other hand, the melting point refers to a temperature at which an object in a solid phase is heated and changes to a liquid phase, that is, a temperature at which melting or infinite slowing is performed.

According to the conductive paste of the present invention, the flowability of the glass in the conductive film is suppressed by the high softening point lead silicate glass frit with respect to the conductive film obtained by using the conductive paste. Thus, the structure of the conductive film is made dense, and the plating resistance and the solder resistance are enhanced.

The low softening point zinc borosilicate glass frit enhances the wettability between the paste and the base such as a dielectric porcelain, and enhances the adhesion between the conductive film and the base. No appearance or peeling occurs, and the appearance is good.

Furthermore, by using a low softening point lead borosilicate glass frit, the acid resistance of the conductive film can be increased by adding TiO ₂ having acid resistance, thereby improving the plating resistance and suppressing the deterioration of the conductive film. . In addition, CuO or CrO
The inclusion of such a metal component suppresses the fluidity of the glass, improves the wettability with the metal, improves the sinterability of the metal and the clogged state of the glass, and makes the structure of the conductive film denser. This also improves plating resistance, heat resistance, and solder resistance.

Further, by forming a conductive film using the conductive paste of the present invention, precipitation of the glass frit on the conductive film surface after baking is reduced, and the problem of external shape is eliminated.

As described above, the conductive film obtained by using the conductive paste of the present invention has good external appearance, excellent adhesion to a substrate such as dielectric porcelain, and excellent plating resistance to electrolytic plating. Become. When this conductive film is used, for example, as a terminal electrode of a laminated ceramic capacitor, the appearance is good, the adhesive strength with the dielectric ceramic and the plating resistance to electrolytic plating are excellent, and the solder wettability and heat resistance are excellent. In addition, a terminal electrode having no voids in the electrode film and having good sealing properties with respect to a plating solution can be obtained. In addition, since the fluidity of the glass is suppressed, the push-up phenomenon due to the internal electrode can be suppressed. Further, the acid resistance of the electrode film is increased to improve the plating resistance, and the deterioration of the conductive film can be suppressed, so that the adverse effect on the Q value of the capacitor can be suppressed. Furthermore, in the electroplating, a plating solution does not enter between the terminal electrode and the dielectric porcelain and Q value defect does not occur. Obtainable.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The conductive paste of the present invention will be described below in detail based on specific examples. In the following examples, three terminals of a laminated ceramic capacitor will be described as an application example of the conductive paste, but the application of the conductive paste of the present invention is not limited to this, and the internal electrodes of the laminated ceramic capacitor, The present invention can be applied to various uses in which a conductive paste is generally used, such as a conductive circuit of a printed wiring board using a substrate such as glass or ceramic.

The metal powder used for the conductive paste of the present invention includes Ag, Au, Pt, Pd, Ni, Cu, Pb, and S.
n, Zn, Bi or alloys thereof.
These are used alone or as a mixture of two or more. These powders are used in the form of powder and flake. If the powder is in the form of powder, the specific surface area and tap density thereof are in the ranges of 0.3 to 0.8 m ² / g and 2.8 to 4.0 g / cm ³ , respectively. If present, the specific surface area and tap density are 0.9 to 2.0 m ² / g and 2.0 to 4.0 g / c, respectively.
The range of m ³ is preferable in that the dispersibility and the mixing characteristics are good, the appearance of the coating film of the conductive paste is good, and stable conductive characteristics are easily obtained.

Further, the combination of the powder-shaped powder and the flake-shaped powder is set in a weight ratio range of 2: 3 to 3: 2, preferably 1: 1. Is preferable in that the shape of the electrode film after coating and baking becomes good. If the amount of powder in the powder shape is larger than the above range, the shape of the electrode film tends to be sharp. On the other hand, if there are many flake-shaped powders, the shape of the electrode film tends to be concave, and voids tend to increase in the electrode film.

In general, a laminated ceramic capacitor has a terminal electrode of Ag / Pd composition and a terminal electrode of Ag / Pd composition which is electroplated on a base. Ag / P
A terminal electrode having a d composition is expensive because it contains a large amount of Pd, and is inferior in soldering heat resistance. Ag /
The Pd content in the Pd base is 1 to 10%,
This Pd is used to prevent adhesion of the capacitor chips, prevent floating of the surface of the glass frit, and control metal diffusion between the internal electrode and the terminal electrode. The conductive paste of the present invention performs sintering control with a glass frit even on an Ag underlayer except for expensive Pd for cost reduction.
It can prevent penetration of a plating solution in electroplating.

The high softening point lead silicate glass frit is composed of PbO and SiO ₂ , Na ₂ O, K ₂ O,
It is composed of at least one of Al ₂ O ₃ . The softening point of the lead silicate glass frit having a high softening point is as high as 650 ° C. or more, and preferably 650 to 720 ° C. By setting the softening point to be high as described above, an effect of suppressing the fluidity of the glass frit having a low softening point can be obtained, thereby obtaining an effect of eliminating the phenomenon of pushing up the terminal electrode.

The ratio of the high softening point lead silicate glass frit to the metal powder is preferably set in the range of 3 to 6% by weight. Within this range, the structure of the conductive film becomes dense, and the plating resistance is improved. When the proportion is less than 3% by weight, the effect of densifying the structure of the conductive film cannot be obtained. On the other hand, when it exceeds 6% by weight, the structure of the conductive film is rather coarse and the plating resistance tends to decrease. There is. Also,
When used as a terminal electrode of a laminated ceramic capacitor, the Q value tended to be reduced to 1,000 or less due to electrolytic plating.

[0026] As a specific composition ratio of the high softening point lead silicate-based component of the glass frit, PbO: 40 to 60 wt% SiO _2: 30 to 50 wt% Na ₂ O: 1~10 wt% K ₂ O : 1 to 5% by weight Al ₂ O ₃ : 2 to 15% by weight is preferable. By setting the proportion of PbO to be smaller than that of SiO ₂ as such a composition range, the softening point is increased and the glass is hardly vitrified, whereby the fluidity of the glass of the conductive film can be suppressed.

The low-softening point zinc borosilicate glass frit is composed of ZnO, B ₂ O ₃ , SiO ₂ , Na
_It consists of ₂ O and K ₂ O. The softening point of the low softening point zinc borosilicate glass frit is 620 ° C or lower, preferably 550 to 620 ° C. By setting the softening point in this manner, an effect of improving the wettability between the paste and the substrate such as porcelain is achieved, thereby obtaining the effect of improving the adhesive strength between the electrode film and the substrate.

The ratio of the low softening point zinc borosilicate glass frit to the metal powder is preferably set in the range of 3 to 6% by weight. Within this range, the adhesion between the conductive film and a substrate such as a dielectric ceramic can be enhanced. The above ratio is 3
When the amount is less than 6% by weight, the effect of enhancing the adhesion of the conductive film cannot be obtained. On the other hand, when the amount exceeds 6% by weight, devitrification tends to occur. Zn tends to be easily released.

[0029] As specific composition ratio of the low softening point borosilicate zinc component of the glass frit, ZnO: 35 to 65 wt% B ₂ O _3: 15~45 wt% SiO _2: 5 to 20 wt% Na ₂ O: 1 to 10% by weight is preferred. Within this composition range, the wettability of the conductive paste to a substrate such as a dielectric porcelain will be good, and the adhesion between the conductive film and the substrate will be enhanced. Also,
When used as a terminal electrode of a laminated ceramic capacitor, the occurrence of floating of the electrode film due to the protrusion of the internal electrode can be suppressed, and the adhesive strength with the capacitor body can be increased.

The lead borosilicate glass frit having a low softening point is contained in consideration of further improving the plating resistance, and its component is PbO, B ₂ O ₃ , Si.
It is made of O ₂ , TiO ₂ , CuO, and CrO.
The softening point of the low softening point lead borosilicate glass frit is 620 ° C or lower, and preferably 550 to 620 ° C. By setting the softening point in this manner, the wettability between glass and silver (Ag) is improved, and sintering is controlled and the glass is filled in the voids of the terminal electrodes by interposing CuO and CrO. By acting, the effect of increasing the sealing property of the plating solution by the electrode film can be obtained.

The ratio of the low softening point lead borosilicate glass frit to the metal powder is preferably set in the range of 2 to 15% by weight. Within this range, the acid resistance of the conductive film can be increased to enhance the plating resistance. In addition, the fluidity of the glass is suppressed to improve the wetting with the metal, thereby suppressing the segregation of the surface of the glass. Can be dense. If the ratio is less than 2% by weight, the effect of increasing the acid resistance of the conductive film tends to be lost. In addition, when used as a terminal electrode of a laminated ceramic capacitor, the Q value tended to decrease due to electrolytic plating. On the other hand, when the content exceeds 15% by weight, the conductive film is insulated by the glass and the resistance is increased, so that there is a tendency that a good conductive film cannot be obtained.

[0032] Specific composition ratio of the low softening point lead borosilicate component of the glass frit, PbO: 40 to 80 wt% B ₂ O _3: 1~10 wt% SiO _2: 15 to 45 wt% TiO ₂ : 1 to 10% by weight CuO: 1 to 10% by weight It is preferable that CrO: 1 to 10% by weight. Within this composition range, the plating resistance is improved by TiO _{2 having} acid resistance, the fluidity of the glass is suppressed by the metal components CuO and CrO, and the wettability with metals such as silver is improved. It becomes a conductive film having a dense structure, which also enhances plating resistance and solder resistance. Therefore, when used as a terminal electrode of a laminated ceramic capacitor, an electrode film having excellent plating resistance and solder resistance can be obtained.

Next, an organic vehicle in which various resins are dissolved in an organic solvent is used. As the characteristics of the organic vehicle, it is required that the viscosity and viscosity suitability of the conductive paste obtained by using the organic vehicle can be controlled, a good coating shape can be obtained, and an appropriate dry film strength can be obtained.

As the organic vehicle used for the conductive paste of the present invention, acrylic resin, phenol resin, alkyd resin, rosin ester, ethyl cellulose, methyl cellulose, ethyl hydrocellulose, PVA (polyvinyl alcohol), polyvinyl butyrate, etc. are used as α-terpineol. , BCA (butyl carbitol acetate), benzyl alcohol and the like.

In order to disperse the metal powder and each glass frit in the organic vehicle, a roll mill, a planetary mixer, or the like may be used. In particular, a roll mill is preferable because uniform dispersion can be efficiently performed in a short time.

The ratio of the metal powder and the glass frit dispersed in the organic vehicle is 70 to 80% by weight of the metal powder, 5 to 15% by weight of the glass frit, and 5 to 25% by weight of the organic vehicle in the conductive paste. It is preferable to adjust the total amount to be 100% by weight in the range of from the viewpoint of improving the rheology of the conductive paste and the appearance of the conductive film.

In the conductive paste of the present invention thus obtained, the viscosity can be adjusted to 300 to 500 p (poise) by adjusting the dilution ratio with a solvent, etc. This is preferable in that defects such as sagging and sharpness do not occur. Accordingly, the proportion of the solid content (metal powder and glass frit) in the conductive paste is 75 to 95% by weight as described above.

In order to form a conductive film using the conductive paste of the present invention, the conductive paste is coated on a surface of a dielectric ceramic, glass, ceramic, or the like serving as a base by a method such as dipping (immersion) or printing. A paste film is formed by applying to a shape and a thickness, dried, and baked by a method such as baking to form a conductive film.

In forming the conductive film as described above, the thickness of the paste film is preferably set in the range of 30 to 150 μm, thereby obtaining a conductive film having a good appearance and uniform characteristics. It will be easier. The drying is preferably carried out in a drying oven at a temperature of 130 to 180 ° C. for a time of about 5 to 15 minutes, whereby the shape of the paste film can be controlled. It is easy to obtain a conductive film having a high force and a dense structure. When this drying is performed in an atmosphere of oxygen (O ₂ ),
The strength of the paste film after drying is improved and more preferable. Further, in the case of baking, it is preferable to perform baking using a baking furnace (tunnel furnace) at a temperature of 600 to 900 ° C. for about 30 to 60 minutes, thereby sintering Ag in the conductive film. As a result, it is easy to obtain a conductive film having a good appearance and a high adhesive strength to the substrate, a dense structure, and excellent plating resistance and solder resistance. When this firing is also performed in an atmosphere of O _2, the binder removal in the paste film proceeds,
It becomes more preferable because a good conductive film can be obtained.

Hereinafter, a detailed description will be given based on a specific example. [Example 1] As a metal powder, flake-like and powder-like A
g powder was prepared. The flake-like powder has a specific surface area of 1.5 m ² / g and the tap density of 2.5 g / cm ³ , and the powder-like powder has a specific surface area of 0.52
m ² / g, tap density of 3.3 g / cm ³ ,
The mixture was mixed at a weight ratio of 1: 1.

As the organic vehicle, a solution prepared by dissolving 25% by weight of ethyl cellulose in an organic solvent in which α-terpineol and BCA were mixed at a ratio of 1: 1 was prepared.

As the high softening point lead silicate glass frit, the low softening point zinc borosilicate glass frit, and the low softening point lead borosilicate glass frit, those having the component composition ratios shown in Table 1 were prepared. .

The softening point of each glass frit shown in Table 1 was determined by a thermomechanical analyzer (TMA: Thermo Mechanical Mechanical).
Analysis).

[0044]

[Table 1]

Next, metal powders as solid components, a high softening point lead silicate glass frit, a low softening point zinc borosilicate glass frit, and a low softening point lead borosilicate glass frit are shown in Tables A to E. And 72% by weight of this solid component and 20% by weight of the organic vehicle were mixed. Then, each was kneaded with a planetary mixer for 90 minutes, then dispersed for 45 minutes with a three-roll mill, and the viscosity was adjusted with the above-mentioned organic solvent to obtain conductive pastes A to I having the composition ratios shown in Table 2. Was prepared.

Further, a conductive paste of a comparative example was prepared as follows. Specific surface area 1.0 m ² as metal powder
/ G, flake Ag with tap density of 2.0 g / cm ³
Only prepared. In addition, as a glass frit, Pb
O 70% by weight, SiO ₂ 10% by weight, B ₂ O ₃ 10% by weight, K
_A lead borosilicate glass frit composed of 5% by weight of ₂ O and 5% by weight of Na ₂ O was prepared. As the organic vehicle, a solution prepared by dissolving 25% by weight of ethyl cellulose in an organic solvent in which α-terpineol and BCA were mixed at a ratio of 1: 1 was prepared.

8% by weight of the lead borosilicate glass frit was prepared based on the Ag powder, and 75% by weight of the solid component and 25% by weight of the organic vehicle were mixed. Then, kneading, dispersion, and viscosity adjustment were performed in the same manner as above to prepare a conductive paste J of Comparative Example.

These conductive pastes are made of BaTiO ₃
It was applied to a multilayer ceramic capacitor chip made of a dielectric material, dried at 150 ° C., and sintered at a firing temperature of 780 ° C. to form terminal electrodes of the multilayer ceramic capacitor.

The following evaluation was performed on the terminal electrode films of the respective capacitor samples thus obtained. Regarding the external shape of the electrode film, the surface state was observed using a 20 × stereo microscope, and the occurrence of dents and sharpness on the film surface, sagging of the electrode film edge, and occurrence of moon shape were evaluated. The dents and sharpness were good when the depth or height was 0.4 mm or less. Sauce, moon shape, the amount is 0.3
mm or less was regarded as good.

Regarding the adhesiveness of the electrode film, a pair of lead wires are soldered to each terminal electrode at both ends of the capacitor chip, and the lead wires are pulled in opposite directions, so that the tensile force at the time of breaking the electrode film ( kgf) was measured and evaluated. Then, those having a tensile force of 2 kgf or more were evaluated as good.

Regarding the plating resistance, for the terminal electrodes of each capacitor sample, Sn plating was applied on Ni plating by electrolytic plating, and the Q value of the capacitor before and after the plating was measured. It was sought and evaluated. A sample having a Q value after plating of 1,000 or more and a change in Q value before and after plating within 2,000 was defined as good.

Further, in order to evaluate the bending resistance of the substrate,
Each capacitor sample is 100mm long, 50mm wide, 1.6mm thick
Solder to the mounting land at the center of the glass epoxy board of mm and apply force to the center point of the board with a pressure bar while measuring the capacity with a capacitance measuring machine to bend the board, and the capacity decreased The deflection amount of the substrate at that time was measured and evaluated. And
Those having a deflection amount of 4 mm or more were regarded as good.

The results of the above evaluation are shown in Table 2. In the evaluation result column for each item in the table,
Indicates that the result was good, and X indicates that the result was inferior. Further, those marked with * in the sample column indicate those outside the scope of the present invention.

[0054]

[Table 2]

As is clear from Table 2, the electrode films (samples B to D, F and I) using the conductive paste of the present invention have good appearance and high adhesion to porcelain. Also, Q
High value, small change, and excellent plating resistance.
Further, it can be seen that the substrate has good bending resistance and excellent mechanical strength.

On the other hand, as in Samples A, G and H, the content of the high softening point lead silicate glass frit and the low softening point zinc borosilicate glass frit is less than the range of the present invention, or In the case of 0, the change in the Q value was large, the plating resistance was poor, and the substrate bending resistance was also poor. Further, when the lead silicate glass frit having a high softening point is more than the range of the present invention as in the sample E, the appearance becomes bumpy, the change in the Q value becomes large, the plating resistance is poor, and the resistance to plating is poor. There was a tendency that the substrate bendability was poor.

When the conductive paste J of the comparative example was used, the Q value after plating was largely changed, and the plating resistance was poor.

[Example 2] In preparing a conductive paste in the same manner as in [Example 1], the composition ratios of the respective glass frit were changed, and as shown in Table 3, a, b, and c were used. Three types were prepared.

The metal powder as a solid component and the high softening point lead silicate glass frit, the low softening point zinc borosilicate glass frit, and the low softening point lead borosilicate glass frit are shown in Table 4 below. A conductive paste sample was prepared in the same manner as in [Example 1] except for mixing at each ratio, and each capacitor sample having a terminal electrode formed using the conductive paste sample was prepared.

For these capacitor samples K to S,
Table 4 shows the results of the evaluation performed in the same manner as in [Example 1]. Also in Table 4, those marked with * in the sample column indicate those outside the scope of the present invention.

[0061]

[Table 3]

[0062]

[Table 4]

As is clear from Table 4, electrode films (samples L, M, O, P, R) using the conductive paste of the present invention
Has good appearance and high adhesion to porcelain. Also, the Q value is high and the change is small, and the plating resistance is excellent. Further, it can be seen that the substrate has good bending resistance and excellent mechanical strength.

On the other hand, when the lead silicate glass frit having a high softening point was 0 as in Sample K, the appearance was pushed up and the substrate bending resistance was liable to be inferior.

Further, when the zinc borosilicate glass frit having a low softening point was large as in the sample N, the substrate bending resistance tended to be inferior.

When the low softening point lead borosilicate glass frit is 0 as in sample Q, the adhesive strength is low, the Q value after plating is largely changed, and the plating resistance is poor. There was a tendency that the bendability was poor.

When the lead silicate glass frit having a high softening point is large, as in the case of sample S, precipitation of glass is observed in the external shape, and the Q value after plating is largely changed, resulting in poor plating resistance. In addition, there was a tendency that the substrate bending resistance was poor.

Further, in addition to the case where the conductive paste of the present invention is used for the terminal electrodes of the multilayer ceramic capacitor of the above embodiment, formation of a conductive film on a glass substrate or formation of a conductive film of a thick film circuit A good conductive film having excellent adhesiveness, conductivity, plating resistance and the like was obtained also when used in the above.

[0069]

As described in detail above, according to the present invention,
It was possible to provide a conductive paste having a good external shape and capable of obtaining a conductive film having excellent adhesion to a substrate such as a dielectric ceramic and excellent plating resistance to electrolytic plating.

By forming a conductive film using the conductive paste of the present invention, the appearance is good, the adhesion to a substrate such as a dielectric porcelain and the like, the plating resistance to electrolytic plating are excellent, and the solder wettability is improved. A conductive film having excellent heat resistance and heat resistance can be obtained.

Further, when the conductive paste of the present invention is used for forming electrodes of a laminated ceramic capacitor, for example,
It has good appearance, excellent adhesion to dielectric porcelain, excellent plating resistance to electrolytic plating, excellent solder wettability and heat resistance, and has no voids in the electrode film. Thus, a laminated ceramic capacitor having stable characteristics even with electrolytic plating and soldering treatment was obtained.

Claims (2)

(57) [Claims] 1. A metal powder and 3 to 6 metal powders
Lead silicate-based glass frit having a softening point of 650 ° C. or more by weight%, zinc borosilicate-based glass frit having a softening point of 3 to 6% by weight of 620 ° C. or less, and a softening point of 2 to 15% by weight of 620 ° C. A conductive paste obtained by dispersing the following lead borosilicate glass frit in an organic vehicle. 2. The lead silicate glass frit is made of PbO and SiO ₂ , and at least one of Na ₂ O, K ₂ O and Al ₂ O ₃ , and the zinc borosilicate glass frit is made of ZnO and B ₂ O. ₃ , SiO ₂ , Na ₂ O, K
₂ O, lead borosilicate glass frit is PbO
And _{B 2 O 3, SiO 2,} TiO 2, CuO, claim 1, wherein the conductive paste, characterized in that it consists of CrO.