JP4506763B2 - Conductive paste - Google Patents

Description

  The present invention relates to a conductive paste mainly used for multilayer electronic components.

When manufacturing a multilayer electronic component such as a multilayer inductor, a conductive paste is used to form an internal conductor. After applying this conductive paste to the surface of the green sheet in a predetermined pattern, the green sheet is laminated in a plurality of layers, and a predetermined inner conductor is formed inside the element body made of a magnetic material through a crimping and firing process. Arranged multilayer electronic components can be obtained. As a conventional conductive paste, for example, there is a conductive paste for gravure printing described in Patent Document 1. In the conductive paste for gravure printing, the viscosity is regulated in order to prevent bleeding on the printed matter.
JP 2006-244845 A

  By the way, as a method of applying the conductive paste to the green sheet, in addition to the above-described gravure printing, the conductive paste is applied to the printing mesh by rubbing the printing mesh formed with a predetermined seal with an emulsion or the like with a squeegee. There is screen printing that prints through a predetermined eye. In this screen printing, the thickness of the conductive paste formed on the green sheet is thicker than in the case of gravure printing.

  On the other hand, due to the difference in thickness of the conductive paste formed on the green sheet, thixotropic properties and dilatancy required for the conductive paste used for screen printing are the same as those of the conductive paste used for gravure printing. A thing with a fundamentally different absolute value of a viscosity from a thing. Therefore, when the above-described conventional conductive paste for gravure printing is used for screen printing as it is, there is a problem that the balance between thixotropic property and dilatancy property is poor, and the coating property of the conductive paste cannot be obtained sufficiently. If the applicability is not sufficient, there is a risk of reducing the smoothness of the conductive paste formed on the green sheet and causing printing bleeding.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a conductive paste having good coatability in screen printing.

In order to solve the above problem, the conductive paste according to the present invention is a conductive paste containing conductive powder and a binder resin containing an acrylic resin, and has a viscosity of η0 at a shear rate of 0.4 sec ^−1. .4, the viscosity at a shear rate 4sec ^-1 η4, the viscosity at shear rate 20sec ^-1 when the .eta.20, its viscosity ratio satisfies η0.4 / η4 = 0.51~1.67, and It is characterized by satisfying η0.4 / η20 = 0.49 to 1.68.

  By satisfying the above-mentioned viscosity ratio, this conductive paste has a low shear rate region when applied to the printing mesh in screen printing and a low shear rate region when rubbing the printing mesh with a squeegee. It exhibits suitable thixotropic properties in the process over the shear rate region. Therefore, during printing, the conductive paste quickly passes through the printing mesh, and the occurrence of printing bleeding on the green sheet is suppressed. In addition, this conductive paste exhibits suitable dilatancy in the process from the medium shear rate region to the high shear rate region after being applied to the green sheet. Therefore, the smoothness of the conductive paste formed on the green sheet can be improved.

  Further, the conductive paste satisfies η0.4 = 40 Pa · s to 180 Pa · s, satisfies η4 = 43 Pa · s to 184 Pa · s, and satisfies η20 = 52.1 Pa · s to 163 Pa · s. preferable. In this range, the above-described thixotropic property and dilatancy property can be further optimized.

  The acrylic resin preferably includes one acrylic resin and another acrylic resin having a molecular structure different from that of the one acrylic resin. Thus, by using a plurality of types of acrylic resins, it becomes easy to adjust the viscosity and the viscosity ratio at each shear rate.

  Moreover, it is preferable that electroconductive powder contains one electroconductive powder and the other electroconductive powder from which the said electroconductive powder differs in a particle shape and a particle size. Thus, by using a plurality of types of conductive powder, it becomes easy to bring the resistance value of the internal conductor obtained by firing the conductive paste closer to a desired value.

  In addition, a first conductive paste containing one conductive powder, a binder resin containing one acrylic resin, a second conductive powder, and a second resin containing a binder resin containing another acrylic resin. The conductive paste is preferably mixed. Thus, by mixing the conductive pastes having different components, the viscosity and the viscosity ratio at each shear rate can be adjusted more easily.

  Moreover, it is preferable that binder resin further contains ethylcellulose resin. In this case, the above-described viscosity and viscosity ratio can be more easily satisfied.

  Moreover, it is preferable that content of electroconductive powder is 78 weight%-88 weight%. Furthermore, the conductive powder is preferably silver powder. In this case, it becomes easier to bring the resistance value of the internal conductor obtained by firing the conductive paste closer to a desired value.

  According to the conductive paste according to the present invention, it is possible to have good coating properties in screen printing. As a result, the smoothness of the conductive paste formed in a predetermined pattern on the green sheet can be improved and printing blur can be prevented.

  Hereinafter, preferred embodiments of the conductive paste according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a multilayer inductor manufactured using a conductive paste according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing the layer structure of the multilayer inductor body shown in FIG. As shown in FIG. 1, the multilayer inductor 1 includes a substantially rectangular parallelepiped element body 10 and a pair of external electrodes 12 and 14 formed at both ends in the longitudinal direction of the element body 10.

  As shown in FIG. 2, the element body 10 includes magnetic layers A1, A2, and A20 in which inner conductors are not formed and magnetic layers A3 to A19 in which inner conductors B1 to B17 are formed in a predetermined order. It is configured by stacking. The magnetic layers A1 to A20 have electrical insulation and are integrated so that the boundary cannot actually be visually recognized. The magnetic layers A1, A2, A20 function as protective layers. Further, the inner conductors B <b> 1 to B <b> 17 are electrically connected to each other to form a coil L inside the element body 10.

  More specifically, a linear inner conductor B1 is formed on the surface of the magnetic layer A3. One end of the internal conductor B1 extends to one edge in the longitudinal direction of the magnetic layer A3, and is electrically connected to one external electrode 12. The other end of the internal conductor B1 is electrically connected to a through-hole electrode C1 formed through the magnetic layer A3 in the thickness direction, and is electrically connected to the internal conductor B2 via the through-hole electrode C1. ing.

  On the surfaces of the magnetic layers A4 to A18, substantially U-shaped internal conductors B2 to B16 are formed, respectively. One ends of the internal conductors B2 to B16 are electrically connected to the corresponding through-hole electrodes C1 to C15, respectively. The other ends of the internal conductors B2 to B16 are electrically connected to the through-hole electrodes C1 to C15 and the through-hole electrodes C2 to C16 formed at symmetrical positions with the center of the magnetic layer interposed therebetween.

  Similar to the internal conductor B1, a linear internal conductor B17 is formed on the surface of the magnetic layer A19. One end of the internal conductor B17 is electrically connected to the through-hole electrode C16, and is electrically connected to the internal conductor B16 via the through-hole electrode C16. The other end of the internal conductor B17 extends to the other edge in the longitudinal direction of the magnetic layer A19 and is electrically connected to the other external electrode.

  Further, as shown in FIGS. 3 and 4, the inner conductors B <b> 1 to B <b> 17 forming the coil L are partly in contact with the element body 10, but most of them are separated from the element body 10. That is, there is a gap S between the element body 10 and the coil L (internal conductors B1 to B17).

  Next, a method for manufacturing the multilayer inductor 1 having the above-described configuration will be described.

  First, the conductive paste 20 (see FIG. 5) that is a precursor of the internal conductors B1 to B17 is prepared. In producing the conductive paste 20, first, a first conductive paste obtained by kneading silver powder (conductive powder) in an organic vehicle in which a solvent is mixed with acrylic resin A (a copolymer containing methyl methacrylate). And a second conductive paste obtained by kneading silver powder in an organic vehicle in which a solvent is mixed with acrylic resin B (polymethyl methacrylate) having a molecular structure different from that of acrylic resin A.

  The silver powder content in the first conductive paste and the second conductive paste is in the range of 78 wt% to 88 wt%. As the solvent, for example, α-terpineol, tetralin, butyl carbitol, butyl carbitol acetate is used.

Next, the first conductive paste and the second conductive paste are mixed at a mixing ratio of 1 to 5: 1, thereby producing the above-described conductive paste 20. Viscosity The viscosity of the conductive paste 20 obtained by such mixing, the viscosity at shear rate of 0.4sec ^-1 η0.4, the viscosity at a shear rate 4sec ^-1 η4, at a shear rate of 20sec ^-1 Is η20, η0.4 = 100 Pa · s, η4 = 69 Pa · s, and η20 = 103 Pa · s. The viscosity ratios are η0.4 / η4 = 1.45 and η0.4 / η20 = 0.97.

  Next, the green sheet 30 which is a precursor of the magnetic layers A1 to A20 is produced. The green sheet 30 is a slurry made of ferrite (eg, Ni—Cu—Zn ferrite, Ni—Cu—Zn—Mg ferrite, Cu—Zn ferrite, Ni—Cu ferrite), glass ceramic, or the like. For example by a doctor blade method.

  Next, through holes (not shown) are respectively formed at predetermined positions of the green sheets 30 to be the magnetic layers A3 to A18 by laser processing or the like. And the above-mentioned conductive paste 20 is apply | coated to the surface of each green sheet 30 with a predetermined pattern by screen printing. Then, after passing through the step of drying the conductive paste 20, the green sheets 30 are stacked in the order shown in FIG. 2 as shown in FIG. Further, as shown in FIG. 5B, pressure is applied from the stacking direction to press-bond each green sheet 30 to form a green sheet stack 40.

  After the pressure bonding, the stacked body 40 of the green sheets 30 is cut into chips. Then, for example, the laminated body 40 formed into chips at a temperature of about 900 ° C. is fired. As a result, the green sheets 30 become the magnetic layers A1 to A20, and the conductive paste 20 becomes the internal conductors B1 to B17 and the through-hole electrodes C1 to C16, and the element body 10 is formed.

  Finally, external electrodes 12 and 14 are formed on the element body 10. The external electrodes 12 and 14 are formed by applying an electrode paste mainly composed of silver, nickel, or copper to both ends in the longitudinal direction of the element body 10 and baking at 600 ° C., for example. Thereafter, when a plating layer of Cu, Ni, Sn, or the like is formed on the surfaces of the external electrodes 12, 14, the multilayer inductor 1 shown in FIG. 1 is completed.

  In the multilayer inductor 1 described above, the viscosity of the conductive paste 20 used for forming the inner conductors B1 to B17 satisfies η0.4 = 40 Pa · s to 180 Pa · s, and η4 = 43 Pa · s to 184 Pa · s. And η20 = 52.1 Pa · s to 163 Pa · s. Further, the viscosity ratio satisfies η0.4 / η4 = 0.51 to 1.67 and η0.4 / η20 = 0.49 to 1.68.

  The conductive paste 20 satisfies the above-described viscosity and viscosity ratio, so that in screen printing, a low shear rate region when applied to the printing mesh, and a low shear rate when rubbing the printing mesh with a squeegee. It exhibits suitable thixotropic properties in the process from the region to the medium shear rate region. Accordingly, during screen printing, the conductive paste 20 quickly passes through the printing mesh, and the occurrence of printing bleeding on the green sheet 30 is also suppressed.

  In addition, the conductive paste 20 exhibits suitable dilatancy in the process from the medium shear rate region to the high shear rate region after being applied to the green sheet 30. When the screen plate (not shown) is separated from the green sheet 30, the conductive paste 20 printed on the green sheet 30 and the conductive paste 20 remaining on the screen plate are separated from each other. This is considered to correspond to a high shear rate region.

  Therefore, when the conductive paste 20 exhibits suitable dilatancy in the process from the medium shear rate region to the high shear rate region, the thickness of the conductive paste 20 formed on the green sheet 30 is more than in the case of gravure printing. In the thick screen printing, the smoothness of the conductive paste 20 can be improved. In particular, in the above embodiment, the viscosity ratio of η0.4 / η20 is close to 1, so that the cohesive force after separation of the conductive paste 20 is sufficiently secured, and the thickness variation of the conductive paste 20 is suppressed. Effect is also obtained.

  In this way, the thixotropic property and the dilatancy property of the conductive paste 20 can be exhibited in a balanced manner, and the conductive paste 20 formed on the surface of the green sheet 30 by screen printing can be thinned and thickened. It is. Therefore, even in the case of manufacturing a low-resistance multilayer inductor in which the thickness of the internal conductors B1 to B17 exceeds 70 μm, it is possible to reduce the number of times of printing while improving the linearity of the printed pattern. It becomes.

  The more preferable viscosity of the conductive paste 20 satisfies η0.4 = 90 Pa · s to 180 Pa · s, η4 = 90 Pa · s to 184 Pa · s, and η20 = 78 Pa · s to 163 Pa · s. is there. Further, more preferable viscosity ratios of the conductive paste 20 are η0.4 / η4 = 1.5-1.50 and η0.4 / η20 = 0.88-1.53.

  In addition, the conductive paste 20 contains silver powder in the range of 78 wt% to 88 wt%. For this reason, even if the thickness and width of the internal conductors B1 to B17 are not excessively increased, the resistance values of the internal conductors B1 to B17 obtained by firing the conductive paste 20 can be easily brought close to desired values. This contributes to the miniaturization of the multilayer inductor 1. Furthermore, since the dynamic hardness of the conductive paste 20 is suitable, the shrinkage rate when the conductive paste 20 is fired is larger than the shrinkage rate when the green sheet 30 is fired, and the element obtained after firing is obtained. A gap S (see FIGS. 3 and 4) between the body 10 and the inner conductors B1 to B17 is sufficiently formed. This suppresses the occurrence of a decrease in magnetic saturation when current is passed through the inner conductors B1 to B17.

  The present invention is not limited to the above embodiment. For example, in the embodiment described above, the silver powder contained in the first conductive paste and the second conductive paste is not particularly limited. For example, the silver content in the first conductive paste is about 99%, The silver powder A having a primary particle size of about 0.3 μm to 0.5 μm is contained, and the second conductive paste has a particle shape and a particle size different from those of the one silver powder. Silver powder B made of 1 μm spherical powder may be contained, and these may be mixed to produce a conductive paste. Thus, by using a plurality of types of silver powder, it becomes easy to bring the resistance value of the internal conductor obtained by firing the conductive paste closer to a desired value.

  Moreover, you may make it contain ethyl cellulose resin in either the 1st conductive paste and the 2nd conductive paste. The ethyl cellulose resin is a resin that satisfies the viscosity characteristics at each shear rate described above as a single unit. Therefore, when an ethyl cellulose resin is contained in either the first conductive paste or the second conductive paste, the viscosity and viscosity ratio at each shear rate can be easily adjusted.

  Note that the conductive paste is not necessarily manufactured by mixing the first conductive paste and the second conductive paste, and the conductive paste included in the first conductive paste and the second conductive paste. It may be prepared by kneading a conductive powder, a binder resin, a solvent and the like at a time.

Examples 1 to 4, Reference Examples 1 to 5, and Comparative Examples 1 to 3 are shown below to describe the present invention more specifically. FIG. 6 is a diagram showing the details of the material constituting the conductive paste according to each example and reference example , and the viscosity and viscosity ratio thereof. Moreover, FIG. 7 is a figure which shows the detail of the material which comprises the electrically conductive paste which concerns on each comparative example, its viscosity, and a viscosity ratio.

  For measuring the viscosity of each conductive paste, a viscometer “HBDV-I +” manufactured by BROOKFIELD was used. “SSA14 / 6R” was used as a spindle, and spindle speeds of 1 rpm, 10 rpm, and 50 rpm multiplied by a conversion constant were made to correspond to shear speeds η0.4, η4, and η20. The temperature of the conductive paste during the measurement was 25 ° C. for all.

As shown in FIG. 6, the conductive paste according to Reference Example 1 is obtained by adding silver powder A to an organic vehicle in which α-terpineol as a solvent is blended with acrylic resin A and kneading with a three-roll mill. Produced by mixing a conductive paste of 2 and a second conductive paste obtained by kneading silver powder A in an organic vehicle in which α-terpineol is mixed with ethyl cellulose resin at a mixing ratio of 1: 1. It is.

The viscosity of the conductive paste according to Reference Example 1 was η0.4 = 80 Pa · s, η4 = 79 Pa · s, and η20 = 52.1 Pa · s. The viscosity ratio of the conductive paste according to Reference Example 1 was η0.4 / η4 = 1.01 and η0.4 / η20 = 1.53.

The conductive paste according to Example 1 is a first conductive paste obtained by adding silver powder A to an organic vehicle in which α-terpineol is blended with acrylic resin A and kneading with a three-roll mill, and acrylic resin B. It was prepared by mixing an organic vehicle containing α-terpineol with a second conductive paste obtained by kneading silver powder A at a mixing ratio of 3: 1.

The viscosity of the conductive paste according to Example 1 was η0.4 = 100 Pa · s, η4 = 69 Pa · s, and η20 = 103 Pa · s. The viscosity ratio of the conductive paste according to Example 1 was η0.4 / η4 = 1.45 and η0.4 / η20 = 0.97.

The conductive paste according to Reference Example 2 is a first conductive paste obtained by adding silver powder A to an organic vehicle in which α-terpineol is blended with acrylic resin A and kneading with a three-roll mill, and acrylic resin A. This was prepared by mixing an organic vehicle containing α-terpineol with a second conductive paste obtained by kneading silver powder B at a mixing ratio of 4: 1.

The viscosity of the conductive paste according to Reference Example 2 was η0.4 = 90 Pa · s, η4 = 184 Pa · s, and η20 = 163 Pa · s. Moreover, the viscosity ratio of the conductive paste according to Reference Example 2 was η0.4 / η4 = 0.49 and η0.4 / η20 = 0.55.

The conductive paste according to Reference Example 3 is a first conductive paste obtained by adding silver powder A to an organic vehicle in which α-terpineol is blended with acrylic resin A and kneading with a three-roll mill, and acrylic resin A. This is prepared by mixing an organic vehicle containing α-terpineol with a second conductive paste obtained by kneading silver powder B at a mixing ratio of 1: 1.

The viscosity of the conductive paste according to Reference Example 3 was η0.4 = 40 Pa · s, η4 = 43 Pa · s, and η20 = 82 Pa · s. The viscosity ratio of the conductive paste according to Reference Example 3 was η0.4 / η4 = 0.93 and η0.4 / η20 = 0.49.

Conductive paste according to the second embodiment, changing the mixing ratio of Reference Example 2 and the first conductive paste of the same composition the second conductive paste, 7: were prepared by mixing in a mixing ratio of 3 Is. The viscosity of the conductive paste according to Example 2 was η0.4 = 90 Pa · s, η4 = 90 Pa · s, and η20 = 102 Pa · s. The viscosity ratio of the conductive paste according to Example 2 was η0.4 / η4 = 1.00 and η0.4 / η20 = 0.88.

In the conductive paste according to Reference Example 4 , the mixing ratio of the first conductive paste and the second conductive paste having the same composition as in Reference Example 2 was further changed, and mixed at a mixing ratio of 7.75: 2.25. It is produced by doing. The viscosity of the conductive paste according to Reference Example 4 was η0.4 = 150 Pa · s, η4 = 100 Pa · s, and η20 = 98 Pa · s. The viscosity ratio of the conductive paste according to Reference Example 4 was η0.4 / η4 = 1.50 and η0.4 / η20 = 1.53.

In the conductive paste according to Reference Example 5 , the mixing ratio of the first conductive paste and the second conductive paste having the same composition as in Reference Example 2 was further changed, and mixed at a mixing ratio of 7.5: 2.5. It is produced by doing. The viscosity of the conductive paste according to Reference Example 5 was η0.4 = 180 Pa · s, η4 = 108 Pa · s, and η20 = 107 Pa · s. Moreover, the viscosity ratio of the conductive paste according to Reference Example 5 was η0.4 / η4 = 1.67 and η0.4 / η20 = 1.68.

The conductive paste according to Example 3 is mixed at a mixing ratio of 7.5: 2.5 by changing the mixing ratio of the first conductive paste and the second conductive paste having the same composition as in Example 1. It was produced by this. The viscosity of the conductive paste according to Example 3 was η0.4 = 100 Pa · s, η4 = 76 Pa · s, and η20 = 111.4 Pa · s. The viscosity ratio of the conductive paste according to Example 3 was η0.4 / η4 = 1.32 and η0.4 / η20 = 0.90.

In the conductive paste according to Example 4 , the mixing ratio of the first conductive paste and the second conductive paste having the same composition as in Example 1 was further changed and mixed at a mixing ratio of 8.5: 1.5. It is produced by doing. The viscosity of the conductive paste according to Example 4 was η0.4 = 110 Pa · s, η4 = 70 Pa · s, and η20 = 78 Pa · s. The viscosity ratio of the conductive paste according to Example 4 was η0.4 / η4 = 1.57 and η0.4 / η20 = 1.41.

Using the conductive pastes according to Examples 1 to 4 described above, when the pattern of the internal conductor was screen-printed on the green sheet, printing blur on the green sheet was visually observed in any conductive paste. There wasn't. Moreover, even when the thickness of the pattern of the inner conductor formed in one screen printing was about 20 μm, good smoothness was obtained.

  On the other hand, as shown in FIG. 7, the conductive paste according to Comparative Example 1 was prepared by kneading an organic vehicle in which α-terpineol was mixed with acrylic resin A with silver powder A in a three-roll mill. It is. The viscosity of the conductive paste according to Comparative Example 1 was η0.4 = 60 Pa · s, η4 = 138 Pa · s, and η20 = 124.6 Pa · s. Moreover, the viscosity ratio of the conductive paste according to Comparative Example 1 was η0.4 / η4 = 0.43 and η0.4 / η20 = 0.48.

  The conductive paste according to Comparative Example 2 was prepared by kneading an organic vehicle in which acrylic resin B was mixed with α-terpineol and silver powder A with a three-roll mill. The viscosity of the conductive paste according to Comparative Example 2 was η0.4 = 800 Pa · s, η4 = 176 Pa · s, and η20 = 68 Pa · s. Moreover, the viscosity ratio of the conductive paste according to Comparative Example 2 was η0.4 / η4 = 4.55 and η0.4 / η20 = 2.14.

  The conductive paste according to Comparative Example 3 was prepared by kneading an organic vehicle in which α-terpineol was mixed with ethyl cellulose with silver powder A using a three-roll mill. The viscosity of the conductive paste according to Comparative Example 3 was η0.4 = 150 Pa · s, η4 = 105 Pa · s, and η20 = 70.2 Pa · s. The viscosity ratio of the conductive paste according to Comparative Example 3 was η0.4 / η4 = 1.43 and η0.4 / η20 = 2.14.

Using the conductive pastes according to Comparative Examples 1 to 3 described above, the pattern of the internal conductor was screen-printed on the green sheet. With the conductive paste according to Comparative Example 1, the viscosity η0.4, η4 for each shear rate. , Η20 is within the range of the viscosity of the conductive paste according to the example, but since the viscosity ratios η0.4 / η4 and η0.4 / η20 are smaller than those of the example, the dilatancy was not sufficient. . For this reason, some smoothness is poor and bleeding occurs. Furthermore, when the conductive paste changed over time and stored for several days, separation / sedimentation between the conductive powder, the resin and the solvent was confirmed.

  In addition, the conductive paste according to Comparative Example 2 has too high viscosity ratios η0.4 / η4 and η0.4 / η20 and excessive thixotropic properties. It was difficult to ensure the smoothness of the pattern. Also for the conductive paste according to Comparative Example 3, the viscosity ratio η0.4 / η20 is larger than that of the example, the thixotropic property from the medium shear rate region to the high shear rate region is slightly high, and on the green sheet Smoothness was not maintained.

  From the above, it was confirmed that the conductive paste according to the example had a good balance between thixotropic property and dilatancy property, and had good coating property in screen printing.

It is a perspective view which shows the multilayer inductor manufactured using the electrically conductive paste which concerns on one Embodiment of this invention. FIG. 2 is an exploded perspective view showing a layer configuration of an element body of the multilayer inductor shown in FIG. 1. It is the III-III sectional view taken on the line in FIG. It is the IV-IV sectional view taken on the line in FIG. FIG. 3 is a diagram showing a manufacturing process of the multilayer inductor shown in FIG. 1. It is a figure which shows the detail of the material which comprises the electrically conductive paste which concerns on an Example, its viscosity, and a viscosity ratio. It is a figure which shows the detail of the material which comprises the electrically conductive paste which concerns on a comparative example, its viscosity, and a viscosity ratio.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer inductor, 20 ... Conductive paste, 30 ... Green sheet.

Claims (5)

Conductive powder and, a conductive paste for screen printing comprising a binder resin containing a molecular structure from the one of the acrylic resin to an acrylic resin different from an acrylic resin or ethyl cellulose resin,
The viscosity at a shear rate 0.4sec ^-1 η0.4, the viscosity at a shear rate 4sec ^-1 η4, the viscosity at shear rate 20sec ^-1 when the .eta.20, its viscosity η0.4 = 40Pa · s to 180 Pa · s, η4 = 43 Pa · s to 184 Pa · s, and η20 = 52.1 Pa · s to 163 Pa · s, and the viscosity ratio is η0.4 / η4 = 0.51 1. A conductive paste characterized by satisfying 1.67, satisfying η0.4 / η20 = 0.49 to 1.68, further satisfying η0.4 ≧ η4 and η20> η4 . Wherein the conductive powder is one conductive powder of claim 1, wherein the conductive paste is a conductive powder of the one which comprises a further conductive powder particle shape and particle size are different. A first conductive paste comprising the one conductive powder and a binder resin containing the one acrylic resin;
A second conductive paste comprising the other conductive powder and a binder resin containing the other acrylic resin;
The conductive paste according to claim 2 , wherein the conductive paste is mixed. Content of the said electroconductive powder is 78 weight%-88 weight%, The electrically conductive paste as described in any one of Claims 1-3 characterized by the above-mentioned. The conductive powder of claim 1-4 as described in any one of the conductive paste, which is a silver powder.

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