JP2003281948A - Manufacturing method for conductive paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for conductive paste improving the yield ratio of various electronic parts by controlling a fluctuation in viscosity with time when used for formation of an electrode for the various electronic parts such as a conductor element. <P>SOLUTION: At least metallic powder and a first organic vehicle are mixed (S1). After that, the mixture is made into a paste by dispersing in a roll mill (S2). Following that, the second organic vehicle is added to the dispersed paste and mixed and the viscosity of the paste is adjusted (S3). Then, the paste having adjusted viscosity is dispersed again by the roll mill (S4). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive paste which is suitable for forming electrodes of various electronic parts such as semiconductor elements.

[0002]

2. Description of the Related Art Conventionally, a conductive paste has been known as a material for forming electrodes on various electronic components such as semiconductor elements. Such a conductive paste generally has a metal powder, a glass frit and an organic vehicle, which are mixed and premixed with a mixer, and then uniformly dispersed by a roll mill or the like, and then adjusted to a predetermined viscosity value. It is manufactured by the construction method called.

[0003]

However, in the conventional method, it is often observed that the viscosity of the conductive paste changes with time, and the yield of electronic parts manufactured using the conductive paste is reduced. Is causing the problem.

The inventors of the present invention have diligently studied the cause of the above-described change with time. As a result, the cause is that the resin and the inorganic filler (metal powder and glass frit) in the organic vehicle added for the purpose of adjusting the viscosity after uniform dispersion. It has been found that the adsorption between (1) and () is not in equilibrium. Therefore, the present inventors have studied a method in which the above adsorption reaches more equilibrium during the production of the conductive paste.

An object of the present invention is to provide a method for producing a conductive paste which has a high storage stability for a long period of time.

[0006]

In order to achieve the above object, a method for producing a conductive paste according to the present invention is to prepare a paste by mixing at least a metal powder and a first organic vehicle and then dispersing the mixture with a roll mill. A first step of mixing, a second step of mixing the second paste with the second organic vehicle to adjust the viscosity of the paste, and a third step of dispersing the viscosity-adjusted paste with a roll mill. It is characterized by that.

As the first and second organic vehicles, those having the same composition or different compositions can be appropriately used. And as the resin constituting the organic vehicle, nitrocellulose, ethyl cellulose and the like can be mentioned, and as the solvent, diethylene glycol monobutyl ether acetate, ethylene glycol monobutyl ether, terpineol, solfit, butyl carbitol acetate, diacetone alcohol and the like can be mentioned. To be

According to the above method, after adding the second organic vehicle for the purpose of adjusting the viscosity, the re-dispersion treatment is carried out again by the roll mill, so that the conductive paste produced thereby is a metal powder. Since the adsorption equilibrium of the resin in the organic vehicle with respect to the (inorganic filler) can be further improved, the physical property change (viscosity change) due to adsorption / desorption over time can be suppressed, and the storage stability of the viscosity of the conductive paste can be improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a conductive paste of the present invention will be described in detail with reference to the following examples and comparative examples. The present invention is not limited to these examples.

(Example) A method for producing a conductive paste of this example will be described below with reference to the flow chart shown in FIG.

First, as shown in FIG. 1, Pb-Si-B
The system glass frit (average particle size 3 μm), Ag powder (average particle size 0.5 μm) as the metal powder, and the first organic vehicle were pre-kneaded in a mixer at the compounding ratio shown in Table 1 ( Step 1, hereinafter referred to as S).

Then, the kneaded material (paste) was passed between the rolls of a roll mill three times to perform a dispersion treatment on the kneaded material (S2). Then, the second organic vehicle was added to the kneaded product after the dispersion treatment to adjust the kneaded product after the dispersion treatment to a predetermined viscosity (S3).

Next, the kneaded material whose viscosity has been adjusted is again passed through the roll mill three times for dispersion treatment (by pressure) (S).
4) The electrically conductive paste was manufactured by the above.

[0014]

[Table 1]

The first organic vehicle and the second organic vehicle are, for example, a mixture of nitrocellulose as a resin, diethylene glycol monobutyl ether acetate as a solvent, ethylene glycol monobutyl ether as a solvent, and terpineol as a solvent. Is.

On the other hand, as a comparative example, a comparative conductive paste was manufactured in the same manner as in the above example except that the step S4 was omitted.

Next, the conductive paste of the above example and the comparative conductive paste were respectively stored at 25 ° C.,
The change with time of their viscosity was examined. For the viscosity measurement, a Rion viscometer VT-04 No. 2 rotor was used. The measurement results of those viscosities are also shown in Table 2. As is clear from Table 2, the conductive pastes of Examples are found to have stable viscosity over time as compared with the comparative conductive paste.

[0018]

[Table 2]

FIG. 3 shows the change over time in the pattern forming performance of the conductive paste used in the evaluation of the change over time in the viscosity. The evaluation is based on the screen printing (SU
S200 mesh) pattern, a pattern of conductive paste is printed on the alumina substrate 1, and the pattern is printed at 150 ° C. for 10 minutes.
After drying for 1 minute, the electrode is patterned at 600 ° C. for 1 minute (in-out 5 minutes) to form an electrode pattern 2 based on the above pattern, and then each bus bar 2 of the electrode pattern 2 shown in FIG.
The resistance value between a and a was measured, and the dischargeability of the paste was compared by the resistance value.

As is clear from FIG. 3, the conductive paste of this example can maintain stable patterning performance for 6 months immediately after production (0 months, initial period), but the comparative conductive paste of the comparative example does not. It can be seen that the line resistance between the bus bars 2a increases as the viscosity changes with time, and the amount of paste discharged from the mesh pattern during screen printing decreases with time.

As a result, it is clear that in the semiconductor element in which the electrodes are formed by using the comparative conductive paste, the line resistance value rises and becomes out of the standard value, and the yield decreases.

On the other hand, in the semiconductor element in which the electrode is formed by using the conductive paste of the present embodiment, the increase of the line resistance value can be suppressed more than in the comparative example, and the occurrence of the semiconductor element out of the standard value can be reduced. The yield of the semiconductor device can be improved.

The metal powder is not particularly limited in shape and size, and the existing Ag and C may be used.
The metal powder containing u or Ni as a main component may be used alone, or the metal powder of any alloy of the above main components may be used.
Suitable metal powders include Cu simple substance, Ag simple substance, N
i simple substance, Cu-Ni, Cu-Ag, etc. are mentioned.
Most preferred is g.

Regarding the type of glass frit,
There is no particular limitation, and existing glass frits may be used alone or in combination of two or more.

Further, the organic vehicle containing the resin and the solvent is not particularly limited, and existing organic vehicles may be used alone or in combination of two or more.

[0026]

The method for producing the conductive paste of the present invention comprises:
As described above, the method includes a step of further dispersing the viscosity-adjusted paste with a roll mill.

Therefore, the above method can further improve the adsorption equilibrium of the resin in the organic vehicle with respect to the inorganic filler (metal powder or the like), so that the physical property change due to adsorption and desorption over time can be suppressed and the viscosity of the conductive paste can be suppressed. The storage stability of can be improved.

Therefore, by using the conductive paste according to the above method for forming electrodes of various electronic parts such as semiconductor elements, it is possible to improve the yield of various electronic parts such as semiconductor elements.

[Brief description of drawings]

FIG. 1 is a flowchart showing each step in a method for manufacturing a conductive paste according to an example of the present invention.

FIG. 2 is a plan view of an electrode pattern used for evaluation of printability of the conductive pastes of the examples and comparative examples.

FIG. 3 is a graph showing changes over time in line resistance for comparing and showing the paste discharge amounts of the conductive pastes of the above-described example and comparative example.

Claims (2)

[Claims] 1. A first step of mixing at least a metal powder and a first organic vehicle and then dispersing with a roll mill to form a paste, and mixing the dispersed paste with a second organic vehicle,
A method for producing a conductive paste, comprising: a second step of adjusting the viscosity of the paste, and a third step of dispersing the paste whose viscosity has been adjusted by a roll mill. 2. The method for producing a conductive paste according to claim 1, wherein a glass frit is further mixed with the paste in the first step.