JPH06325614A - Conductive paste - Google Patents

Abstract

PURPOSE:To apply powder in uniform thickness without deformation during applying and drying processes, and enhance reliability without edge cut or the like during a baking process by using mixture conductive powder where globular and flat conductive powders are mixed. CONSTITUTION:In conductive paste including conductive powder, glass frit. and an organic vehicle, mixture conductive powder incorporating globular conductive powder mixed with flat conductive powder is used. Consequently, the globular conductive powder is suitably mixed with the flat conductive powder, thus enhancing a shape holding property, preventing generation of a recess or the like during a drying process of the applied conductive paste, and restraining contraction of an applying layer during a baking process so as to prevent generation of edge cut. As a result, in the case of formation of an external electrode for ceramic electronic parts, it is possible to form an applying layer having a uniform thickness, and further to form the external electrode having high reliability without any deficiency such as edge cut during a baking process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste, and more particularly to a conductive paste for forming external electrodes of ceramic electronic parts such as laminated ceramic capacitors.

[0002]

2. Description of the Related Art In conventional conductive pastes used for forming external electrodes (terminal electrodes) of ceramic electronic parts such as monolithic ceramic capacitors, spherical conductive powders are usually used as conductive powders (eg Cu powders). Is used, and a conductive paste is formed by mixing glass frit and an organic vehicle with this spherical conductive powder.

[0003]

However, like the above-mentioned conventional conductive paste, the external electrode of the ceramic electronic component (for example, a laminated ceramic capacitor) is formed by using a conductive paste using only spherical conductive powder. If
It is difficult to apply the conductive paste on the ceramic electronic component (element) with a uniform thickness. For example, as shown in FIG.
There is a problem that the recess 13 is formed in the central portion of the end face side where the thickness of the conductive paste (external electrode) 12 applied to the outermost part is maximum.

Further, since it is difficult to apply a uniform thickness and the film thickness at the edge portion becomes thin, the external electrodes formed on the ceramic electronic component 11 in the baking process after drying as shown in FIG. 12 has a problem that an edge breakage (the external electrode 12 is disconnected at the edge portion 14) occurs.

The present invention solves the above-mentioned problems, and when it is used to form an external electrode of a ceramic electronic component such as a monolithic ceramic capacitor, deformation such as a dent does not occur in the coating and drying step, It is an object of the present invention to provide a conductive paste that can be applied to a uniform thickness and that can form highly reliable external electrodes without causing edge breakage or the like in the baking process. .

[0006]

In order to achieve the above object, the conductive paste of the present invention is a conductive paste for forming an external electrode of a ceramic electronic component such as a laminated ceramic capacitor, which is spherical conductive powder. And a flat conductive powder, mixed glass powder, glass frit, and organic vehicle.

The conductive powder is Cu powder, and the ratio of the flat conductive powder (Cu powder) is in the range of 10 to 50% by weight based on the whole conductive powder (Cu powder). To do.

In the conductive paste of the present invention, the spherical conductive powder is not limited to the true spherical conductive powder,
It is a concept that includes a slightly deformed spherical or non-flat polyhedral conductive powder.

[0009]

[Function] As the conductive powder, the mixed conductive powder obtained by mixing the spherical conductive powder and the flat conductive powder is used, so that the spherical conductive powder and the flat conductive powder are appropriately entangled with each other to maintain the shape. Property is improved, the occurrence of deformation such as dents in the drying step of the applied conductive paste is prevented, the contraction of the coating layer in the baking step is suppressed, and the occurrence of edge breakage can be prevented. .

Therefore, when forming an external electrode of a ceramic electronic component such as a monolithic ceramic capacitor,
While it is possible to form a coating layer with a uniform thickness,
It is possible to form a highly reliable external electrode that does not cause a defect such as edge breakage in the baking process.

Further, since it becomes possible to suppress the contraction of the external electrodes in the baking process, the stress applied to the ceramic electronic component element body (for example, the laminated ceramic capacitor element body) is reduced to prevent the occurrence of defects such as cracks. It will be possible.

[0012]

EXAMPLES Hereinafter, examples of the present invention will be shown together with comparative examples, and the features thereof will be described in more detail.

In preparing the conductive paste of this example, the following materials were used and they were compounded in the following compounding ratios. Conductive powder type: Cu powder (spherical powder and flat-shaped powder) Mixing ratio: 70 wt% with respect to conductive paste Glass frit type: Mixed frit of zinc borosilicate and barium borosilicate Mixing ratio: 5 with respect to conductive paste Weight% Organic vehicle Type (composition): Acrylic resin dissolved in butyl cellosolve Blending ratio: 25% by weight to conductive paste

Then, the compounding ratio of the spherical powder of Cu powder and the flat-shaped powder in the conductive paste in which the respective materials were compounded in the above ratios was changed in the ratios shown in Table 1.

Then, an external electrode (terminal electrode) of a ceramic electronic component (multilayer ceramic capacitor in this embodiment) was formed using the sample (conductive paste) thus prepared. FIG. 1 is a plan view showing a laminated ceramic capacitor in which external electrodes 2 are formed on both ends of a rectangular parallelepiped laminated ceramic capacitor (element body) 1 using the conductive paste of this embodiment.

Then, the state of the external electrode 2 formed as described above (whether or not dents or edge breakage occurred, etc.) was examined, and the magnitude of the capacitance that could be obtained from the monolithic ceramic capacitor 1 was measured. The results are shown in Table 1.

[0017]

[Table 1]

In Table 1, samples marked with * are samples having compositions outside the scope of the present invention (comparative examples), and others are samples having compositions within the scope of the present invention (examples). Is.

As shown in Table 1, in the external electrode formed using the conductive paste (Sample No. 1) using only spherical Cu powder containing no flat Cu powder,
Occurrence of dimples in the drying process and edge breakage in the baking process were observed. Furthermore, since the shrinkage in the baking process is large, the capacitance is decreased due to disconnection.

Further, the flat C-shape of the whole Cu powder is used.
The external electrodes formed by using the conductive paste (Sample Nos. 6 and 7) in which the proportion of the u powder exceeded 50% by weight were found to have a poor appearance (protrusions during the baking process).

On the other hand, the external electrode formed by using the conductive paste (Sample Nos. 2 to 5) in which the ratio of the flat Cu powder to the entire Cu powder is in the range of 10 to 50% by weight is the drying step. No deformation such as dents was formed, and a coating layer having a uniform thickness could be formed, and even after baking, no edge breakage or protrusion was observed, and no decrease in capacitance was observed.

Therefore, the ratio of the flat Cu powder to the entire Cu powder is preferably in the range of 10 to 50% by weight.

Although the external electrode formed by using the conductive paste of the present invention can be used as it is, in order to improve characteristics such as solder wettability, for example, Ni plating + Sn plating, It is also possible to perform processing such as Ni plating + solder plating.

In the above embodiment, the conductive powder is C
Although the case where u powder is used has been described, in the conductive paste of the present invention, the conductive powder is not limited to Cu powder, and other metal powder such as Ag powder,
Alternatively, an alloy powder such as Ag-Pd powder can be used as the conductive powder.

Further, in the above embodiment, the case where the external electrode of the laminated ceramic capacitor is formed by using the conductive paste of the present invention has been described. However, the conductive paste of the present invention is formed only by the external electrode of the laminated ceramic capacitor. However, it can be used for forming external electrodes of various ceramic electronic components such as ceramic semiconductors and PTC thermistor devices.

The present invention is not limited to the above-mentioned embodiments in other points as well, and relates to the kinds of glass frit and organic vehicle, the mixing ratio of conductive powder, glass frit and organic vehicle, and the like. Various applications and modifications can be made within the scope of the gist.

[0027]

As described above, the conductive paste of the present invention uses the mixed conductive powder obtained by mixing the spherical conductive powder and the flat conductive powder as the conductive powder.
When forming an external electrode of a ceramic electronic component such as a monolithic ceramic capacitor, deformation such as a dent does not occur in the coating and drying step, and coating can be performed with a uniform thickness.

Further, since it can be applied to a uniform thickness, it is possible to prevent the occurrence of edge breakage in the baking process and, for example, when it is used for forming an external electrode of a monolithic ceramic capacitor. It is possible to form a highly reliable external electrode capable of stably obtaining a predetermined electrostatic capacity.

Further, by blending the flat conductive powder, the shrinkage ratio of the external electrode can be suppressed,
It is possible to reduce the stress applied to the ceramic electronic component (element) and prevent the occurrence of defects such as cracks.

[Brief description of drawings]

FIG. 1 is a plan view showing a ceramic electronic component (multilayer ceramic capacitor) in which external electrodes are formed using the conductive paste of the present invention.

FIG. 2 is a plan view showing a state in which a dent is generated in a coating layer in a drying process after applying a conventional conductive paste.

FIG. 3 is a plan view showing a state in which edge breakage has occurred in an external electrode formed using a conventional conductive paste.

[Explanation of symbols]

1 Ceramic electronic component (multilayer ceramic capacitor) 2 External electrode (conductive paste)

Claims (2)

[Claims] 1. A conductive paste for forming an external electrode of a ceramic electronic component such as a monolithic ceramic capacitor, which is a mixed conductive powder in which spherical conductive powder and flat conductive powder are mixed, glass frit, and an organic material. A conductive paste containing a vehicle. 2. The conductive powder is Cu powder, and
The conductive paste according to claim 1, wherein the proportion of the flat conductive powder (Cu powder) is in the range of 10 to 50% by weight based on the whole conductive powder (Cu powder).