JP5934560B2 - Conductive metal paste - Google Patents

Description

  The present invention relates to a conductive metal paste, and more particularly to a paste used for forming a metal wiring or a conductive film by a screen printing method.

  Conventionally, it is known to use a so-called screen printing method for forming a metal wiring or a conductive film in a manufacturing process of an electronic device. In the screen printing method, a substrate made of glass, silicon, or the like and a screen plate with an opening pattern are placed opposite to each other, and a conductive metal paste is spread evenly on the surface of the screen plate using a scraper, so that the screen plate surface is spread. Scanning is performed while pressing the squeegee. Thus, the conductive metal paste is applied to the substrate surface through the opening pattern of the screen plate, and the conductive metal paste corresponding to the opening pattern is printed on the substrate surface. Then, by firing the printed conductive metal paste, the dispersing agent that covers the surface of the metal fine particles of the conductive metal paste is detached, and the metal fine particles are sintered together to obtain a conductive metal wiring.

  By the way, in recent years, in order to improve the performance of electronic devices, further reduction in resistance of metal wiring is required. A method for further reducing the resistance of metal wiring is known, for example, from Patent Document 1. In this case, a conductive metal paste containing both metal fine particles and a metal filler as a metal solid content and further containing a varnish-like resin that prevents dripping and bleeding is used, and this conductive metal paste is applied to the substrate surface, for example, 1 μm. It is made to apply with the above thickness. When the conductive metal paste is applied to a thickness of 1 μm or more, depending on the substrate surface state, dripping and bleeding cannot be completely prevented, and the adhesion of the metal wiring to the substrate after firing is reduced. To do. From this, it is conceivable to increase the amount of additive such as the varnish-like resin.

  Even if the conductive metal paste described in Patent Document 1 is applied to the surface of the substrate, it may still sag or bleed, and the adhesion of the fired metal wiring to the substrate may decrease. In order to improve the adhesion between the metal wiring and the substrate while suppressing such sagging and bleeding, it is conceivable to increase the amount of the above-mentioned species, but many additives generally have polarity. It is difficult to dissolve in a low polarity solvent.

  The present inventors diligently studied and solubilized the polyimide varnish in a low-polarity solvent by using a polyimide varnish which is one kind of varnish-like resin and adding a fatty acid amide as a surfactant together with this polyimide varnish. I found. Here, if the addition amount of a polyimide varnish is increased, the adhesiveness of an electroconductive metal paste will become high. In this case, the conductive metal paste sticks without being easily detached from the squeegee or scraper, and as a result, there is a problem that the conductive metal paste cannot be continuously applied to a plurality of substrates. Therefore, it is conceivable to dilute the conductive metal paste with a solvent (that is, increase the ratio of the solvent) to reduce the adhesiveness of the conductive metal paste.

  However, when the conductive metal paste is diluted with a solvent, the metal solid content concentration (concentration of metal fine particles) is lowered, and even if the conductive metal paste is applied thickly, the thickness of the metal wiring after firing becomes thin. There is. In addition, there is a problem that sagging and bleeding that have been suppressed by the additive reoccur.

International Publication No. 2002/035554

  In view of the above points, it is an object of the present invention to provide a low-adhesive conductive metal paste that can reliably suppress the occurrence of sagging and bleeding even when the conductive metal paste is applied thickly on the substrate surface. Is.

  In order to solve the above problems, the present invention provides a conductive metal paste comprising a low-polarity solvent, metal fine particles coated with a dispersant on a surface, a polyimide varnish, and a fatty acid amide, and comprising an unsaturated fatty acid alkyl It is characterized by further including ester.

  According to the present invention, a low-polarity solvent having a lower viscosity than that of a polar solvent is used as a solvent. Therefore, even when the amount of added polyimide varnish is increased while the metal solid content concentration is kept high, the conductive metal paste can be applied. It does not decline. Since this polyimide varnish has polarity, it is difficult to dissolve the polyimide varnish in a low polarity solvent. Therefore, the conductive metal paste of the present invention contains a fatty acid amide as a surfactant. When the hydrophilic group of the fatty acid amide is directed to the polyimide varnish and the hydrophobic group is directed to the low polarity solvent, the low polarity solvent and the polyimide varnish are emulsified (emulsified). Thereby, a sufficient amount of polyimide varnish can be dissolved in the low polarity solvent. Therefore, even if the conductive metal paste is applied thickly on the surface of the substrate, the occurrence of sagging and bleeding can be suppressed.

  Here, when the addition amount of the polyimide varnish is increased, the adhesiveness of the conductive metal paste is increased, and the conductive metal paste is stuck to the squeegee or scraper used for applying the conductive metal paste.

  The conductive metal paste of the present invention further contains an unsaturated fatty acid alkyl ester. This unsaturated fatty acid alkyl ester lowers the adhesiveness of the conductive metal paste due to its surfactant action. By reducing the adhesiveness of the conductive metal paste, the conductive metal paste is easily detached from the squeegee or scraper used for the application and does not stick. In addition, since the unsaturated fatty acid alkyl ester has a double bond in its alkyl chain, it is oxidized and polymerized by oxygen in the air immediately after the conductive metal paste is applied to the substrate surface. When oxidative polymerization of unsaturated fatty acid alkyl ester occurs, the conductive metal paste partially polymerizes, and in combination with the action of the polyimide varnish, dripping and bleeding occur even when the conductive metal paste is applied thickly. It can be reliably suppressed.

  In the present invention, it is more preferable that the unsaturated fatty acid alkyl ester comprises a polyunsaturated fatty acid alkyl ester. Since polyunsaturated fatty acid alkyl esters have a plurality of double bonds in the alkyl chain, oxidative polymerization is promoted compared to the case of using unsaturated fatty acid alkyl esters having one double bond, and dripping and bleeding occur. It can be further suppressed. The ratio of the polyunsaturated fatty acid alkyl ester contained in the unsaturated fatty acid alkyl ester is not particularly limited, but an unsaturated fatty acid alkyl ester comprising 10% by mass or more of the polyunsaturated fatty acid alkyl ester is more preferably used. can do.

  In this invention, it is preferable that carbon number of the alcohol part of the said unsaturated fatty acid alkyl ester exists in the range of 1-8. When the number of carbon atoms in the alcohol portion exceeds 9, there is a problem that sintering of the metal fine particles is inhibited during firing. Moreover, it is preferable that carbon number of the alkyl chain of the fatty acid part of the said unsaturated fatty acid alkyl ester is in the range of 6-20. Not only is it difficult to obtain an unsaturated fatty acid alkyl ester having 6 or less carbon atoms in the alkyl chain of the fatty acid moiety, but the occurrence of dripping or bleeding of the conductive paste after coating may not be sufficiently suppressed. On the other hand, when the carbon number of the alkyl chain in the fatty acid portion exceeds 20, there may be a problem that the resistance of the metal wiring after firing becomes high.

  In the present invention, by further including polyamide, the polyamide crosslinks between the metal fine particles, so that thixotropic property can be further enhanced. According to this, even if the scanning speed of the squeegee is increased and the application speed of the conductive metal paste is increased, dripping and bleeding can be prevented.

  In the present invention, a metal filler having an average particle diameter of 1 to 20 μm may be further included. In this case, when the total of the metal filler and the metal fine particles is 100% by weight, the ratio of the metal filler is preferably in the range of 50 to 95% by weight. If the ratio of the metal filler is less than 50% by weight, it is difficult to increase the thickness of the metal wiring obtained by screen printing. Furthermore, even if the thickness of the metal wiring can be increased, firing is performed. Occasionally, the detachment of the dispersant from the surface of the metal fine particles becomes insufficient, resulting in a problem that the resistance of the metal wiring after firing becomes high. On the other hand, if the ratio of the metal filler exceeds 95% by weight, there is a problem that the sintering of the metal fillers through the metal fine particles becomes insufficient and the resistance of the metal wiring after firing becomes high.

  The metal used in the present invention is at least one metal selected from Ag, Au, Cu, Ni, Pd, In, Sn, Rh, Ru, Pt, In, and Sn, or at least two of these metals. It can be appropriately selected depending on the purpose and application.

  Hereinafter, the conductive metal paste according to the embodiment of the present invention will be described using an Ag paste as an example. The Ag paste of the present embodiment includes a low-polarity solvent, Ag fine particles whose surface is coated with a dispersant, a polyimide varnish as an additive for preventing dripping and bleeding, and a fatty acid amide as a surfactant, It further contains an unsaturated fatty acid alkyl ester that lowers the adhesiveness of the conductive metal paste and suppresses dripping and bleeding after printing.

  As the Ag fine particles, those having an average particle diameter in the range of 1 nm to 50 nm can be used. As a brand name of a commercial product, Ag nano metal ink Ag1T (made by ULVAC, Inc.) can be mentioned, for example. When the average particle diameter is less than 1 nm, the specific surface area increases and the amount of the dispersant covering the surface of the Ag fine particles increases, so that the detachment of the dispersant becomes insufficient during firing, and the resistance value of the Ag wiring is high. The trouble that becomes. On the other hand, when the average particle diameter exceeds 50 nm, there arises a problem that the dispersibility of Ag fine particles in the Ag paste is lowered.

  As the dispersant for coating the Ag fine particle surface, it is preferable to use at least one of a fatty acid having 6 to 18 carbon atoms and an aliphatic amine having 6 to 18 carbon atoms. In the case of fatty acids or aliphatic amines having less than 6 carbon atoms, there is a problem that the dispersibility of Ag fine particles in the Ag paste is lowered. On the other hand, in the case of a fatty acid or aliphatic amine having 19 or more carbon atoms, the detachment of the fatty acid or aliphatic amine from the surface of the Ag fine particles becomes insufficient during firing, resulting in a problem that the resistance value of the Ag wiring film increases.

  As the fatty acid, for example, carboxylic acid can be used. Specifically, C6 hexanoic acid, 2-ethylbutyric acid, neohexanoic acid (2,2-dimethylbutyric acid); C7 heptanoic acid, 2-methylhexanoic acid, cyclohexanecarboxylic acid; C8 Octanoic acid, 2-ethylhexanoic acid, neooctanoic acid (2,2-dimethylhexanoic acid); Nonanoic acid having 9 carbon atoms; Decanoic acid having 10 carbon atoms, neodecanoic acid (2,2-dimethyloctanoic acid); At least one selected from the group consisting of undecanoic acid, dodecanoic acid having 12 carbon atoms, tetradecanoic acid having 14 carbon atoms, palmitic acid having 16 carbon atoms, and stearic acid, oleic acid, linoleic acid, and linolenic acid having 18 carbon atoms. It is preferable.

  Examples of aliphatic amines include hexylamine, cyclohexylamine, and aniline having 6 carbon atoms; heptylamine having 7 carbon atoms; octylamine having 8 carbon atoms; 2-ethylhexylamine; nonylamine having 9 carbon atoms; decylamine having 10 carbon atoms; At least one selected from dodecylamine having 12 carbon atoms and tetradodecylamine having 14 carbon atoms can be preferably used.

  As the polyimide polyimide varnish, it is preferable to use a imide ring closed ring (for example, a ring closing rate of 40% or more). According to this, the solubility of the polyimide varnish with respect to a low polarity solvent can further be improved. Moreover, since the polyimide varnish is excellent in heat resistance, it does not deteriorate even if the applied Ag paste is baked at a temperature of 200 ° C. or higher, for example.

  Examples of the fatty acid amide include methylene bis stearic acid amide, methylene bis palmitic acid amide, methylene bis behenic acid amide, hexamethylene bis stearic acid amide, ethylene bis stearic acid amide, ethylene bis behenic acid amide, and ethylene bis-12. -Selected from hydroxystearic amide, trimethylene 1,3 bis stearic amide, tetramethylene bis stearic amide, distearyl sebacic amide, distearyl adipic amide, ethylene bisoleic amide and xylylene bis stearic amide At least one kind can be preferably used alone or in combination. As a brand name of a commercial product, DISPARLON A603-10X, A603-20X, 6900-10X, 6900-20X, PFA-131 (made by Enomoto Kasei Co., Ltd.) can be mentioned, for example. In addition, the manufacturing method of fatty acid amide is disclosed by Unexamined-Japanese-Patent No. 11-293158, for example.

  If the unsaturated fatty acid alkyl ester contains a polyunsaturated fatty acid alkyl ester having two or more double bonds in the alkyl chain of the fatty acid part, compared to the case of using one having one double bond Oxidative polymerization is promoted, and dripping and bleeding of the Ag paste described later may be further suppressed. In this case, the ratio of the polyunsaturated fatty acid alkyl ester contained in the unsaturated fatty acid alkyl ester is not particularly limited, but more preferably an unsaturated fatty acid alkyl ester comprising 10% by mass or more of the polyunsaturated fatty acid alkyl ester. It can be preferably used. Moreover, it is preferable that carbon number of the alcohol part of unsaturated fatty-acid alkylester exists in the range of 1-8. When the number of carbon atoms in the alcohol portion exceeds 9, there is a problem that the sintering of Ag fine particles is inhibited during firing. Moreover, it is preferable that carbon number of the alkyl chain of the fatty acid part of unsaturated fatty acid alkyl ester exists in the range of 6-20. Not only is it difficult to obtain an unsaturated fatty acid alkyl ester having 6 or less carbon atoms in the alkyl chain of the fatty acid moiety, but the occurrence of dripping or bleeding of the conductive paste after coating may not be sufficiently suppressed. On the other hand, when the carbon number of the alkyl chain in the fatty acid portion exceeds 20, there may be a problem that the resistance of the metal wiring after firing becomes high. Examples of unsaturated fatty acid alkyl esters include methyl oleate, ethyl oleate, butyl oleate, hexyl oleate, octyl oleate, methyl linoleate, ethyl linoleate, butyl linoleate, hexyl linoleate, octyl linoleate, Methyl linolenate, ethyl linolenate, butyl linolenate, hexyl linolenate, octyl linolenate and soy fatty acid methyl, soy fatty acid ethyl, soy fatty acid ethyl, soy fatty acid butyl, soy fatty acid hexyl, soy fatty acid octyl, At least one selected from linseed oil fatty acid methyl, linseed oil fatty acid ethyl, linseed oil fatty acid butyl, linseed oil fatty acid hexyl, and linseed oil fatty acid octyl can be used alone or in combination.

  Moreover, it is preferable to adsorb | suck a silane coupling agent to the surface of Ag microparticles | fine-particles. As the silane coupling agent, for example, those having an amino group and an alkoxy group such as aminoalkyltrialkoxysilane such as aminopropyltrimethoxysilane and aminopropyltriethoxysilane can be used. According to this, when the applied Ag paste is baked, the alkoxy group is hydrolyzed to become an OH group, and this OH group is dehydrated and condensed to provide excellent adhesion to the substrate surface, while the amino group is Bonds strongly with metal surfaces. As a result, excellent adhesion can be obtained between the metal wiring after firing and the substrate surface. Furthermore, since the amino group is strongly bonded to the metal surface in this way, dripping and bleeding of the Ag paste can be effectively suppressed in combination with the action of the polyimide varnish.

  As the low polarity solvent, at least one liquid hydrocarbon selected from octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, toluene, xylene, cyclododecane, cyclododecene, octylbenzene, dodecylbenzene, alone or in combination. Can be used.

  The Ag paste of the present embodiment can further include an Ag filler having an average particle diameter in the range of 1 μm to 20 μm. In this case, when the total of the Ag fine particles and the Ag filler is 100% by weight, the ratio of the Ag filler is preferably in the range of 50 to 95% by weight. When the Ag filler ratio is less than 50% by weight (the Ag fine particle ratio is 50% by weight or more), it is difficult to increase the film thickness of the Ag wiring obtained by screen printing, and the film thickness of the Ag wiring. Even if the thickness can be increased, the detachment of the dispersing agent from the surface of the Ag fine particles becomes insufficient during firing, resulting in a problem that the resistance of the Ag wiring after firing becomes high. On the other hand, when the ratio of Ag filler exceeds 95% by weight (when the ratio of Ag fine particles is 5% by weight or less), the sintering of Ag fillers through Ag fine particles becomes insufficient, and the resistance of Ag wiring after firing becomes low. The trouble of becoming high arises.

  The Ag paste of this embodiment can further contain polyamide. According to this, thixotropic property is imparted to the Ag paste by crosslinking the polyamide to the Ag fine particles. As the polyamide, at least one kind of polyamide wax synthesized by a known method such as polycondensation of dibasic acid and diamine, polycondensation of dibasic acid derivative or dimer acid and diamine, or ring-opening polymerization of lactam is used. be able to. As a brand name of a commercial product, DISPARLON 3900EF (made by Enomoto Kasei Co., Ltd.) can be mentioned, for example.

  As the metal, in addition to the above Ag, for example, at least one metal selected from Au, Cu, Ni, Pd, Rh, Ru, Pt, In and Sn, or an alloy composed of at least two of these metals is used. Depending on the purpose and application, it can be appropriately selected. Hereinafter, a method for producing a conductive metal paste will be described by taking an example of producing an Ag paste as an example.

  First, a dispersion liquid of Ag fine particles having an average particle diameter of 1 nm to 50 nm is placed in a glass container, and a solvent such as toluene is removed using an evaporator. As a result, Ag fine particles whose surface is coated with at least one of the fatty acid having 6 to 18 carbon atoms and the aliphatic amine having 6 to 18 carbon atoms are obtained.

  In addition, when making a silane coupling agent adsorb | suck to Ag fine particle surface, a silane coupling agent is added and stirred to Ag fine particle with an average particle diameter of 1 nm-50 nm. A polar solvent such as acetone is added to the stirred mixture to precipitate Ag fine particles, and the supernatant liquid is discharged by decantation or the like (hereinafter, this operation is referred to as “cleaning step”). This washing process is repeated a plurality of times, the solvent is removed, and Ag fine particles having the silane coupling agent adsorbed on the surface are obtained.

  Next, the Ag fine particles, the imide ring-closed polyimide varnish, the fatty acid amide, the unsaturated fatty acid alkyl ester, and the low polarity solvent composed of hydrocarbon are blended at a predetermined ratio. In this case, the Ag fine particle ratio is 60 to 90% by weight, the polyimide varnish ratio is 0.4 to 3% by weight, the fatty acid amide ratio is 0.5 to 3% by weight, and the unsaturated fatty acid alkyl ester ratio is 0.00. 5 to 10% by weight, and the proportion of the low polarity solvent is preferably in the range of 5 to 30% by weight. Then, an Ag paste is obtained by kneading the above blended material with a three-roll mill.

  In addition, when apply | coating Ag paste by the thickness of 10 micrometers or more, you may mix | blend Ag filler with an average particle diameter of 1-20 micrometers with the said Ag microparticles | fine-particles as Ag solid content. In this case, when the total of the Ag filler and the Ag fine particles is 100% by weight, the ratio of the Ag filler is preferably in the range of 50 to 95% by weight. Moreover, if the polyamide is blended at a ratio of 0.2 to 4% by weight, the thixotropic property of the Ag paste can be further enhanced.

  Since the Ag paste of the present embodiment described above uses a low polarity solvent having a viscosity lower than that of a polar solvent as a solvent, the addition of polyimide varnish while maintaining a high Ag solid content concentration (concentration of Ag fine particles and Ag filler). Even if the amount is increased, the Ag paste can be applied uniformly. Since this polyimide varnish has polarity, it is difficult to dissolve the polyimide varnish in a low polarity solvent, but the Ag paste of this embodiment contains a fatty acid amide as a surfactant. The hydrophilic group of this fatty acid amide is directed to the polyimide varnish and the hydrophobic group is directed to the low polarity solvent, so that the low polarity solvent and the polyimide varnish are emulsified (emulsified), and a sufficient amount of the polyimide varnish is dissolved in the low polarity solvent. it can.

  Here, when the addition amount of the polyimide varnish is increased, the adhesiveness of the Ag paste increases, and the conductive metal paste sticks without being easily detached from the squeegee or scraper. This causes a problem that the conductive metal paste cannot be applied continuously.

  Therefore, the Ag paste of this embodiment further contains an unsaturated fatty acid alkyl ester. Since this unsaturated fatty acid alkyl ester lowers the adhesiveness of the conductive metal paste due to its surfactant action, the conductive metal paste is not easily detached from the squeegee or scraper for printing. In addition, since the unsaturated fatty acid alkyl ester has a double bond in the alkyl chain, it is oxidized and polymerized by oxygen in the air immediately after the Ag paste is applied to the substrate surface. When such an oxidative polymerization of unsaturated fatty acid alkyl ester occurs, the Ag paste is partially polymerized, and in combination with the action of the polyimide varnish, dripping and bleeding may occur even if the Ag paste is applied thickly. It can be reliably suppressed. Thus, as a result of intensive studies by the present inventors, the addition of unsaturated fatty acid alkyl ester can surely suppress the occurrence of dripping or bleeding of the Ag paste while reducing the adhesiveness of the conductive metal paste. I came to know. In addition, when saturated fatty acid alkyl ester in which the alkyl chain does not have a double bond was added, it was confirmed that dripping or bleeding of the Ag paste occurred although the adhesiveness of the Ag paste could be lowered.

Examples of the present invention will be described below.
Example 1
Ag fine particles having an average particle size of 4 nm (trade name “Ag Nanometal Ink Ag1T” manufactured by ULVAC, Inc.) are placed in a glass container, and toluene as a solvent is distilled off using an evaporator to form Ag fine particles (hereinafter “Ag fine particles”). I got). 5 parts by weight of the Ag fine particles thus obtained, 45 parts by weight of an Ag filler having an average particle diameter of 2.1 μm (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industry), and fatty acid amide (manufactured by Enomoto Kasei) 0.5 parts by weight of the product name “DISPARLON A603-10X”), 1.0 part by weight of the ring-closed polyimide varnish (trade name “COMPOSELLA AA” manufactured by Arakawa Chemical), and one double bond in the alkyl chain 1.6 parts by weight of methyl oleate and 7.4 parts by weight of dodecylbenzene were blended. And what was mix | blended was knead | mixed with a 3 roll mill, and Ag paste was obtained. The obtained Ag paste was applied onto the surface of the glass substrate by a screen printing method, printed, and baked at 230 ° C. for 20 minutes. The dripping and bleeding of the printed Ag paste were suppressed, and no sticking of the Ag paste to the printing squeegee or scraper was observed. The film thickness of the Ag wiring after firing was 19.8 μm, the line width was 163 μm, the specific resistance was 11.3 μΩ · cm, and it was confirmed that the resistance of the Ag wiring can be reduced.

(Example 2)
The same procedure as in Example 1 was performed except that 1.6 parts by weight of ethyl oleate was added instead of methyl oleate. Also in this Example 2, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 20.3 μm, the line width was 165 μm, and the specific resistance was 11.4 μΩ · cm. The same results as in Example 1 were obtained.

(Example 3)
Instead of methyl oleate, it was the same as Example 1 except that 1.6 parts by weight of butyl oleate was blended. Also in Example 3, dripping or bleeding of the Ag paste was suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 19.2 μm, the line width was 165 μm, and the specific resistance was 12.2 μΩ · cm. The same results as in Example 1 were obtained.

Example 4
Instead of methyl oleate, it was the same as Example 1 except that 1.6 parts by weight of hexyl oleate was blended. Also in this Example 4, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 20.1 μm, the line width was 162 μm, and the specific resistance was 12.3 μΩ · cm. The same results as in Example 1 were obtained.

(Example 5)
Instead of methyl oleate, it was the same as Example 1 except that 1.6 parts by weight of octyl oleate was blended. Also in this Example 5, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 18.9 μm, the line width was 158 μm, and the specific resistance was 11.9 μΩ · cm, and the same results as in Example 1 were obtained.

(Example 6)
5 parts by weight of the Ag fine particles obtained in Example 1 above, 45 parts by weight of Ag filler (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industry), and fatty acid amide (trade name “DISPARLON A603 manufactured by Enomoto Kasei) -10X "), 0.5 parts by weight of a ring-closed polyimide varnish (trade name" COMPOCELAN AA "manufactured by Arakawa Chemical Co., Ltd.) 1.0 part by weight, and methyl linoleate having two double bonds in the alkyl chain. 6 parts by weight and 7.4 parts by weight of dodecylbenzene were blended. In the same manner as in Example 1, the blended material was kneaded to obtain an Ag paste, and this Ag paste was printed on the surface of the glass substrate by a screen printing method. Also in Example 6, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 20.2 μm, the line width was 142 μm, and the specific resistance was 13.8 μΩ · cm, so that the resistance of the Ag wiring could be reduced.

(Example 7)
Instead of methyl linoleate, the same procedure as in Example 6 was performed except that 1.6 parts by weight of ethyl linoleate was blended. Also in this Example 7, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 21.3 μm, the line width was 138 μm, and the specific resistance was 14.1 μΩ · cm. The same results as in Example 6 were obtained.

(Example 8)
Instead of methyl linoleate, the same procedure as in Example 6 was performed except that 1.6 parts by weight of butyl linoleate was blended. Also in this Example 8, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 22.1 μm, the line width was 144 μm, and the specific resistance was 14.2 μΩ · cm. The same results as in Example 6 were obtained.

Example 9
Instead of methyl linoleate, the same procedure as in Example 6 was performed except that 1.6 parts by weight of hexyl linoleate was blended. Also in this Example 9, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 22.1 μm, the line width was 136 μm, and the specific resistance was 14.4 μΩ · cm. The same results as in Example 6 were obtained.

(Example 10)
Instead of methyl linoleate, the same procedure as in Example 6 was performed except that 1.6 parts by weight of octyl linoleate was blended. Also in Example 10, the dripping or bleeding of the Ag paste was suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 21.4 μm, the line width was 141 μm, and the specific resistance was 13.7 μΩ · cm. The same results as in Example 6 were obtained.

(Example 11)
5 parts by weight of the Ag fine particles obtained in Example 1 above, 45 parts by weight of Ag filler (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industry), and fatty acid amide (trade name “DISPARLON A603 manufactured by Enomoto Kasei) -10X "), 0.5 parts by weight of the ring-closed polyimide varnish (trade name" COMPOCELAN AA "manufactured by Arakawa Chemical Co., Ltd.), and 1.0 part by weight of methyl linolenate having 3 double bonds in the alkyl chain. 5 parts by weight and 8.5 parts by weight of dodecylbenzene were blended. In the same manner as in Example 1, the blended material was kneaded to obtain an Ag paste, and this Ag paste was printed on the surface of the glass substrate by a screen printing method. In Example 11 as well, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 23.0 μm, the line width was 120 μm, and the specific resistance was 12.8 μΩ · cm, so that the resistance of the Ag wiring could be reduced.

(Example 12)
It replaced with methyl linolenate and was carried out similarly to the said Example 11 except the point which mix | blends 0.5 weight part of ethyl linolenate. Also in this Example 12, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 22.6 μm, the line width was 118 μm, and the specific resistance was 13.3 μΩ · cm. The same results as in Example 11 were obtained.

(Example 13)
Instead of methyl linolenate, it was the same as Example 11 except that 0.5 part by weight of butyl linolenate was blended. Also in Example 13, dripping or bleeding of the Ag paste was suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 24.4 μm, the line width was 123 μm, and the specific resistance was 12.9 μΩ · cm, and the same results as in Example 11 were obtained.

(Example 14)
The same procedure as in Example 11 was performed except that 0.5 part by weight of hexyl linolenate was added instead of methyl linolenate. Also in this Example 14, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 24.5 μm, the line width was 116 μm, and the specific resistance was 13.1 μΩ · cm. The same results as in Example 11 were obtained.
(Example 15)
Instead of methyl linolenate, it was the same as Example 11 except that 0.5 part by weight of octyl linolenate was blended. Also in this Example 15, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 24.4 μm, the line width was 114 μm, and the specific resistance was 13.1 μΩ · cm. The same results as in Example 11 were obtained.

(Example 16)
5 parts by weight of the Ag fine particles obtained in Example 1 above, 45 parts by weight of Ag filler (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industry), and fatty acid amide (trade name “DISPARLON A603 manufactured by Enomoto Kasei) -10X ")), 0.5 parts by weight of the ring-closed polyimide varnish (trade name" COMPOCELAN AA "manufactured by Arakawa Chemical Co., Ltd.) and 1.0 part by weight of soybean fatty acid octyl comprising a plurality of unsaturated fatty acid alkyl esters. 8 parts by weight and 8.2 parts by weight of dodecylbenzene were blended. In the same manner as in Example 1, the blended material was kneaded to obtain an Ag paste, and this Ag paste was printed on the surface of the glass substrate by a screen printing method. Also in this Example 16, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 17.8 μm, the line width was 106 μm, and the specific resistance was 5.6 μΩ · cm, so that the resistance of the Ag wiring could be reduced.

(Example 17)
The procedure was the same as Example 16 except that the soy fatty acid octyl was increased to 1.6 parts by weight and the dodecylbenzene was reduced to 7.4 parts by weight. Also in this Example 17, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 23.4 μm, the line width was 110 μm, and the specific resistance was 7.8 μΩ · cm. The same results as in Example 16 were obtained.

(Example 18)
The procedure was the same as Example 16 except that the soy fatty acid octyl was increased to 2.4 parts by weight and the dodecylbenzene was reduced to 6.6 parts by weight. Also in this Example 18, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 21.9 μm, the line width was 124 μm, and the specific resistance was 12.0 μΩ · cm. The same results as in Example 16 were obtained.

(Example 19)
In the same manner as in Example 18 except that 0.5 part by weight of linseed oil fatty acid octyl composed of a plurality of unsaturated fatty acid alkyl esters is blended instead of soybean fatty acid octyl and 8.5 parts by weight of dodecylbenzene is blended. did. Also in this Example 19, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 23.2 μm, the line width was 113 μm, and the specific resistance was 13.0 μΩ · cm. The same results as in Example 18 were obtained.

(Example 20)
Except that the linseed oil fatty acid octyl was increased to 1.0 part by weight and 8.0 parts by weight of dodecylbenzene was blended, it was the same as Example 19 above. Also in the present Example 20, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The thickness of the Ag wiring after firing was 23.6 μm, the line width was 123 μm, and the specific resistance was 15.1 μΩ · cm. The same results as in Example 19 were obtained.

(Example 21)
2.5 parts by weight of Ag fine particles, 47.5 parts by weight of Ag filler (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industry) (ie, the proportion of Ag filler is 95% by weight), soybean The same procedure as in Example 16 was performed except that the fatty acid octyl was increased to 1.6 parts by weight and the dodecylbenzene was decreased to 7.4 parts by weight. Also in this Example 21, dripping and bleeding of the Ag paste were suppressed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 23.4 μm, the line width was 112 μm, and the specific resistance was 9.1 μΩ · cm, so that the resistance of the Ag wiring could be reduced.

(Example 22)
25 parts by weight of Ag fine particles, 25 parts by weight of Ag filler (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industries) (ie, the proportion of Ag filler is 50% by weight), and 8% of dodecylbenzene. The same procedure as in Example 21 was performed except that the content was increased to 4 parts by weight. Also in Example 22, no dripping or bleeding of the Ag paste was observed, and no sticking of the Ag paste to the squeegee or the like was observed. The film thickness of the Ag wiring after firing was 15.1 μm, the line width was 122 μm, and the specific resistance was 8.1 μΩ · cm, so that the resistance of the Ag wiring could be reduced.

Next, a comparative example for the above embodiment will be described.
(Comparative Example 1)
5 parts by weight of Ag fine particles, 45 parts by weight of Ag filler (trade name “Silcoat AgC-2011” manufactured by Fukuda Metal Foil Powder Industry) (ie, the proportion of Ag filler is 90% by weight), and fatty acid amide (Tomomoto Kasei) Product name "DISPARLON A603-10X") 0.5 parts by weight, ring-closed polyimide varnish (trade name "Composelan AA" made by Arakawa Chemical) 1.0 parts by weight, no double bond in the alkyl chain 1.6 parts by weight of methyl laurate and 8.5 parts by weight of dodecylbenzene were blended to obtain an Ag paste. In the same manner as in Example 1, the obtained Ag paste was applied onto the surface of the glass substrate by screen printing, printed, and baked at 230 ° C. for 20 minutes. In this comparative example 1, unlike the above examples, the printed Ag paste was noticeably dripped and smudged, and the line width of the Ag wiring after firing was expanded to 250 μm. The film thickness was 19.7 μm, and the specific resistance was 13.8 μΩ · cm.

Claims (7)

A low-polarity solvent, fine metal particles coated with a dispersant having at least one of a fatty acid having 6 to 18 carbon atoms and an aliphatic amine having 6 to 18 carbon atoms in the fatty acid portion , a polyimide varnish, and a fatty acid amide A conductive metal paste containing
The average particle diameter of the metal fine particles is in the range of 1 nm to 50 nm,
A conductive metal paste further comprising an unsaturated fatty acid alkyl ester.   2. The conductive metal paste according to claim 1, wherein the unsaturated fatty acid alkyl ester comprises a polyunsaturated fatty acid alkyl ester.   The conductive metal paste according to claim 1 or 2, wherein the alcohol part of the unsaturated fatty acid alkyl ester has a carbon number in the range of 1 to 8.   The conductive metal paste according to any one of claims 1 to 3, wherein the alkyl chain of the fatty acid portion of the unsaturated fatty acid alkyl ester has a carbon number in the range of 6 to 20.   The conductive metal paste according to any one of claims 1 to 3, further comprising polyamide.   The conductive metal paste according to any one of claims 1 to 5, further comprising a metal filler having an average particle diameter of 1 to 20 µm.   7. The conductive metal paste according to claim 6, wherein the metal filler is in the range of 50 to 95% by weight when the total of the metal filler and the metal fine particles is 100% by weight.