JP2014053404A - Wiring treatment composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for improving conductivity of wiring formed by using conductive ink.SOLUTION: A wiring treatment composition causes a gap of wiring to be reduced by applying composition comprising formic acid copper (II), amine, formic acid, and further an alcohol to metal wiring formed of metallic copper and/or metallic silver, and by heating the metal wiring at temperature of 100°C or higher.

Description

  The present invention relates to a composition for wiring processing formed of a conductive paste. More specifically, the present invention relates to a composition for improving electrical conductivity by forming a metal electrode and a metal wiring by coating or printing and then heating to fill a void in the wiring.

  Conventionally, as a method of forming a metal electrode or metal wiring on a substrate or electronic component, after plating metal on the substrate or electronic component, this is masked with a photoresist or the like, and the unmasked metal is removed by etching. Have been widely used. However, this method is suitable for forming highly conductive fine wiring, but has a problem that the number of processes is large and metal resources are wasted.

  In addition to the above method, a method of forming an electrode or an electric wiring by heating or applying a conductive paste on a substrate and then forming it is widely used. In this method, the number of processes is small, and metal resources are also effectively used. As metals, silver, aluminum and the like have been put into practical use and widely used. Many of these pastes use metal fine particles, and the fine particles are aggregated and fused by heating to form electrodes and wirings. However, it is difficult for the fine particles to completely aggregate and fuse, and there are many voids. If there are voids in the wiring, the conductivity, the wiring strength, and the durability are lowered, and when cleaning the wiring, a chemical solution or the like remains in the void, which causes trouble.

  As a method of filling the voids of the metal particles, a method in which substitutional electroless plating with silver is applied to an element formed of a copper paste (see Patent Document 1) is applied to a metal other than copper particles and copper, and the copper metal and A method (see Patent Document 2) for firmly joining metals other than copper is disclosed. However, although silver is highly conductive, it is an expensive metal and cannot be said to be an industrially advantageous method. In addition, using a metal other than silver or copper for bonding results in a decrease in conductivity.

  Then, the method of covering the surface of a metal particle layer with copper plating is disclosed (refer patent documents 3-5). However, since these methods plate only the surface layer, the internal voids are not improved.

  As described above, there is no known method for improving the voids of the copper particles with copper that is industrially easily available and inexpensive while maintaining the high conductivity of copper.

JP 2010-225990 A Japanese Patent Laid-Open No. 11-251751 JP 2007-335430 A JP-A-7-283538 JP 2004-214703 A

  This invention is made | formed in view of said subject, and it is providing the composition which fills the space | gap of the wiring formed with the electrically conductive paste, and improves electroconductivity, intensity | strength, and durability.

  As a result of intensive studies on a composition for improving a wiring formed of a conductive paste, the present inventor has found a novel fact that a composition containing copper formate, an amine and formic acid can improve a void of a metal wiring, The present invention has been completed.

  That is, the present invention is a composition as shown below.

  [1] A wiring treatment composition comprising copper (II) formate, an amine and formic acid.

  [2] The composition as described in [1] above, wherein the wiring is a metal wiring formed of a conductive paste.

  [3] The composition as described in [1] or [2] above, wherein the wiring is metallic copper and / or metallic silver.

  [4] The composition according to any one of [1] to [3], wherein the amine is an alkanolamine.

  [5] The composition according to any one of [1] to [4], wherein the amine is ethanolamine.

  [6] The amine is monoethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, aminoethylethanolamine, N, N, N′-trimethylaminoethyl It is at least one selected from the group consisting of ethanolamine, N- (2-hydroxyethyl) morpholine, N- (2-hydroxyethyl) piperazine, N-methyl-N ′-(2-hydroxyethyl) piperazine. The composition according to any one of [1] to [5] above.

  [7] The composition according to any one of [1] to [6] above, further comprising an alcohol.

  [8] The composition according to any one of [1] to [7], wherein the composition is heated to a temperature of 100 ° C. or more after being applied to the metal wiring to reduce the wiring gap.

  The composition for wiring treatment of the present invention can improve the conductivity, strength and durability of wiring using a conductive paste often used in the production of electronic devices such as printed wiring boards and solar cells. Very useful.

  The composition for wiring processing of the present invention can improve the conductivity, strength, durability and the like of a wiring formed with a conductive paste. A conductive paste such as silver or copper contains fine particles, and a wiring formed of the conductive paste has voids between these fine particles. Due to this gap, the conductivity, strength, and durability of the wiring are reduced.

  The wiring processing composition of the present invention improves the conductivity, strength, and durability of the wiring by penetrating into the voids, depositing and filling copper into the voids, and reducing the voids. Moreover, with respect to the wiring formed with the conductive silver paste, the migration problem in which silver ions move can be suppressed by processing with the wiring processing composition of the present invention.

  The essential components of the composition for wiring treatment of the present invention are copper (II) formate, amine and formic acid.

  The composition for wiring processing of the present invention fills the metal copper gap. Copper (II) formate is reduced upon heating to become metallic copper and develops conductivity. In addition, when copper formate (II), an amine, and formic acid of the composition for wiring processing are mixed, a part or all of copper (II) formate is changed to an amine complex salt of copper and is easily reduced during heating.

  In the composition for wiring processing according to the present invention, the copper formate (II) to be used is not particularly limited, and those that are generally distributed can be used, and can be synthesized from other raw materials and used. . In general, copper (II) formate is often distributed in the form of a hydrate. The hydrate may be used as it is, or may be used after dehydration. However, dehydration is preferable because the conductivity becomes higher after the wiring process.

  In order to synthesize copper (II) formate from other raw materials, it is easy to synthesize from other copper salts and formic acid. There is no restriction | limiting in particular in copper salt, For example, copper inorganic acid salt, copper organic acid salt, copper hydroxide, copper oxide etc. are mentioned. The anion component of the copper salt that can be used in the composition for wiring processing of the present invention is preferably a component that can be easily removed by heating. Examples of preferred copper salts include copper nitrate, copper hydrogen carbonate, copper carbonate, copper oxalate, copper acetate, copper formate, copper citrate, copper sulfosalicylate, copper oxide, and copper hydroxide. Among these, copper formate is particularly preferable because it exhibits the highest conductivity.

  These copper salts may be used alone or in combination of two or more.

  As the copper salt, a salt of a monovalent copper ion can be used, and a salt of a divalent copper ion can be used. From the viewpoint of stability and solubility, a salt of a divalent copper ion is preferably used.

  These copper salts may be reacted with formic acid in advance to form copper (II) formate and then added to the wiring treatment composition of the present invention. In the wiring processing composition of the present invention, the copper salt and formic acid may be added. May be used as copper (II) formate.

  In the composition for wiring processing of the present invention, an amine is added to promote reduction of copper (II) formate and to protect metallic copper. The amine is preferably an alkanolamine, and more preferably ethanolamine, which is industrially easily available and inexpensive. Stability can be improved by using alkanolamine. Also, alkanolamines are not easily solidified even when carbon dioxide in the air is absorbed, the physical properties of the composition are not impaired, and copper oxidation by oxygen in the air can be suppressed.

  In the composition for wiring treatment of the present invention, the alkalamine refers to a compound having an amino group and a hydroxyl group in the alkylene chain. Ethanolamine, which is produced most industrially among alkanolamines, is a compound having an amino group and a hydroxyl group at both ends of an ethylene chain. Examples of ethanolamine include monoethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, aminoethylethanolamine, N, N, N′-trimethylamino. Examples include ethylethanolamine, N- (2-hydroxyethyl) morpholine, N- (2-hydroxyethyl) piperazine, N-methyl-N ′-(2-hydroxyethyl) piperazine and the like. Any of these ethanolamines may be used, and two or more kinds may be mixed and used.

  In the composition for wiring processing according to the present invention, the formic acid is not particularly limited, and generally used formic acid can be used. Normally, formic acid is distributed as a water-containing product or an anhydrous product, which can be used in any way, and using formic acid with a low water content will form a highly conductive copper film and copper wiring. This is preferable because the composition for wiring processing has good stability.

  In the composition for wiring processing of the present invention, the amount of formic acid is defined by the amount of amine. Formic acid is used to neutralize the amine and maintain the wiring composition of the present invention from neutral to acidic. When neutral to acidic, it is stable in the atmosphere. When basic, copper formate is hydrolyzed or carbon dioxide is absorbed by moisture in the atmosphere, and the physical properties of the wiring treatment composition change.

  In order to maintain the composition for wiring treatment of the present invention from neutral to acidic, it is necessary that the number of moles of amine × the number of nitrogen atoms in the amine molecule ≦ the number of moles of formic acid.

  In the composition for wiring treatment of the present invention, the amount of copper formate (II), amine and formic acid is preferably 1 to 50% by weight, more preferably 10 to 50% by weight, from the viewpoint of conductivity. preferable. The amount of amine is preferably 1 to 50% by weight, more preferably 5 to 50% by weight, from the viewpoint of the solubility and improvement effect of copper (II) formate. The amount of formic acid is preferably 1 to 50% by weight, more preferably 5 to 50% by weight from the viewpoint of conductivity.

  The composition for wiring processing of the present invention may contain alcohol. Alcohol can adjust the viscosity of the conductive ink, can suppress the volatilization of amine, and can improve the adhesion to the substrate. There is no restriction | limiting in particular as alcohol to add, What is generally added to the ink can be used. For example, monoalcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, cyclohexanol and terpineol; polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, glycerin and sorbitol; And ether alcohols such as propylene glycol, methoxyethanol, ethoxyethanol, and butoxyethanol;

  Moreover, amines other than an anticorrosive, a solvent, a thickener, surfactant, and ethanolamine can be added to the composition for wiring processing of the present invention. As these additives, those commonly used can be used, and there is no particular limitation. Anticorrosives are effective in suppressing copper oxidation after forming a copper film and copper wiring, and solvents, thickeners, and surfactants can improve ink application and stability. Amines other than ethanolamine are used to adjust the volatility and viscosity of the wiring treatment composition and to stabilize copper salts and copper metals.

  The composition for wiring treatment of the present invention is used for forming copper wiring such as a printed wiring board and a solar cell, and is expected to have an effect that the wiring can be made highly conductive.

  As a manufacturing method of a copper wiring, after apply | coating the composition for wiring processing of this invention to a board | substrate, a conductive copper wiring can be formed by heating. There is no restriction | limiting in particular in the board | substrate to be used, For example, ceramics, glass, a plastics etc. are mentioned. Many methods, such as an inkjet and screen printing, are known as a method of apply | coating the composition for wiring processes, and any method can apply | coat without a problem.

  The heating temperature at the time of heating is preferably 100 ° C. or higher, particularly preferably 120 to 200 ° C., in order to decompose formate such as copper formate. The higher the temperature, the more excellent the conductivity and the film and the wiring can be formed.

  Even when oxygen, moisture, carbon dioxide, or the like is present during heating, a highly conductive copper film or copper wiring can be formed. However, when heated in an inert gas atmosphere or a hydrogen gas atmosphere with little oxygen, moisture, carbon dioxide, etc., the conductivity is further increased.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In order to simplify the notation, the following abbreviations were used.

AEEA: N- (2-aminoethyl) ethanolamine DEA: diethanolamine HEM: N- (2-hydroxyethyl) morpholine MEA: monoethanolamine MDEA: N-methyldiethanolamine MMEA: N-methylethanolamine Example 1
A copper paste made of copper metal, resin, and terpineol having an average particle diameter of 90 nm was screen-printed on a glass substrate and baked at 200 ° C. in a nitrogen stream to form a copper wiring. The volume resistance was 29 μΩ · cm, and the cross section was observed with SEM and the porosity was calculated to be 60%.

  Copper (II) formate (10 g) (0.065 mol) and MMEA (18 g, 0.240 mol) were mixed. Further, formic acid (2 g, 0.043 mol) and diethylene glycol (2 g) were added, kneaded, and wiring processing paste (for wiring processing). Composition) was prepared. This paste was screen printed on the copper wiring and fired at 160 ° C. in a nitrogen stream. The volume resistance was 12 μΩ · cm, the cross section was observed with SEM, and the porosity was calculated to be 50%.

Comparative Example 1
Without using an amine, 2 g (0.043 mol) of formic acid was added to 10 g (0.065 mol) of copper (II) formate and kneaded to prepare a wiring treatment paste. This wiring treatment paste was screen-printed on the same copper wiring used in Example 1, and baked at 160 ° C. in a nitrogen stream. The copper wiring turned brown and its volume resistance increased to 175 μΩ · cm. Since no amine was used, the conductivity was poor.

Comparative Example 2
Without using copper (II) formate, 2 g (0.043 mol) of formic acid was added to 18 g (0.240 mol) of MMEA and mixed to prepare a wiring treatment composition. The same copper wiring as used in Example 1 was immersed in this wiring processing composition for 1 hour at room temperature, and fired at 160 ° C. in a nitrogen stream. Its volume resistance was 29 μΩ · cm. As a result of observing the cross section with SEM, the porosity was also unchanged at 60%.

Examples 2-6
Copper wiring was formed with copper paste. This copper wiring was immersed in a wiring processing composition having the composition shown in Table 1 for 1 hour at room temperature and dried in nitrogen. This operation was repeated twice, and heat treatment was performed at a treatment temperature shown in Table 1 under a nitrogen stream. In the composition shown in Table 1, the balance is ethanol. Table 1 shows the volume resistance of the wiring before and after the treatment.

Example 7
Commercially available (Fujikura Kasei Co., Ltd. grade XA-9053) silver ink is applied to a polyimide substrate by screen printing and heated at 200 ° C in the air to form a silver wiring in a comb shape (line / space = 300μm / 300μm) Formed. Two of these substrates were prepared, and one of them was screen-printed with the wiring treatment paste used in Example 1 on the silver wiring and baked at 160 ° C. in a nitrogen stream.

  Two substrates were subjected to a migration test at 25 ° C., a humidity of 60%, and an applied voltage of 100V. The substrate that was not treated with the wiring treatment paste was short-circuited after 180 hours, but the substrate that was treated with the wiring treatment paste was not short-circuited even after 240 hours.

  By using the composition of the present invention, it is possible to obtain a wiring having strength and durability in addition to improvement in conductivity.

Claims (8)

A wiring treatment composition comprising copper (II) formate, an amine and formic acid. The composition according to claim 1, wherein the wiring is a metal wiring formed of a conductive paste. The composition according to claim 1, wherein the wiring is metallic copper and / or metallic silver. The composition according to any one of claims 1 to 3, wherein the amine is an alkanolamine. The composition according to claim 1, wherein the amine is ethanolamine. The amine is monoethanolamine, N-methylethanolamine, N, N-dimethylethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, aminoethylethanolamine, N, N, N′-trimethylaminoethylethanolamine, It is at least one selected from the group consisting of N- (2-hydroxyethyl) morpholine, N- (2-hydroxyethyl) piperazine, and N-methyl-N ′-(2-hydroxyethyl) piperazine. Item 6. The composition according to any one of Items 1 to 5. Furthermore, alcohol is included, The composition in any one of Claims 1-6 characterized by the above-mentioned.   The composition according to claim 1, wherein the composition is heated at a temperature of 100 ° C. or higher after being applied to the metal wiring to reduce the wiring voids.