JP2007073267A - Conductive film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive film especially excellent in sulfidation resistance, and its manufacturing method. <P>SOLUTION: The conductive film includes conductive particles having silver particles and/or copper particles and a triazine thiol derivative. The triazine thiol derivative is considered to form the conductive particles, which have silver particles and/or copper particles, and a complex. As shown in Figure, it is considered that the triazine thiol derivative is firmly bonded to the surface of each silver particle. By this, the sulfidation resistance of the conductive film is effectively improve. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductive film particularly excellent in sulfidation resistance and a method for producing the same.

  In recent years, inkjet methods and various printing methods have been used for fine formation of circuit patterns formed on the surface of a circuit board. The conductive film constituting the circuit pattern contains conductive particles such as silver. Silver is very often used as metal particles contained in a conductive film because of its low resistance and low cost.

By the way, the circuit pattern needs to have good sulfidation resistance. This is because if the sulfidation resistance is low, the conductivity deteriorates.
JP-A-64-53495 JP-A-4-65463

  However, the above-described circuit pattern containing silver, copper, or the like has a problem of low resistance to sulfidation. In particular, dilute inks such as the ink jet method contain only about several wt% of a protective colloid agent with respect to silver, and many of the ink jet methods and various printing methods cannot form a thick conductive film. (Submicron level) Therefore, it was greatly affected by the environment, and the progress of corrosion and deterioration was accelerated.

  Patent Document 1 and Patent Document 2 described above contain a triazine thiol derivative on the surface of the substrate or in the substrate, and the effect thereof is improvement of adhesion, etc. In particular, Patent Document 1 and Patent Document 2 does not describe the sulfidation resistance of the conductive film.

  Therefore, the present invention is to solve the above-described conventional problems, and in particular, an object of the present invention is to provide a conductive film excellent in sulfidation resistance and a manufacturing method thereof.

The conductive film in the present invention is
It contains conductive particles having silver particles and / or copper particles and a triazine thiol derivative.

  The triazine thiol derivative is considered to form a complex with the conductive particles, thereby improving the sulfidation resistance of the conductive film.

  In the present invention, if the triazine thiol derivative contains fluorine, the water repellency is improved, and the sulfidation resistance can be effectively improved.

Moreover, the manufacturing method of the electrically conductive film in this invention is
It has the following processes.

(A) a step of forming a conductive ink containing a triazine thiol derivative in an aqueous solution or alcohol solution of conductive particles having silver particles and / or copper particles;
(B) A step of applying and baking the conductive ink on a substrate.
By the above, the electrically conductive film excellent in sulfidation resistance can be formed easily and appropriately.

  In the present invention, in the step (a), adding a triazine thiol derivative containing an alkali metal salt to the aqueous solution of the conductive particles can increase the solubility of the triazine thiol derivative in the aqueous solution of the conductive particles. Thus, a conductive film having excellent sulfidation resistance can be formed easily and effectively.

  Moreover, in this invention, it is preferable to apply | coat the said conductive ink on the said board | substrate by inkjet or screen printing. Thereby, a conductive film having excellent resistance to sulfidation can be formed on the substrate in a fine shape as a circuit pattern, an electrode, or the like.

  The electrically conductive film in this invention contains the electroconductive particle which has silver particle and / or copper particle, and a triazine thiol derivative.

  The triazine thiol derivative is considered to form a complex with the conductive particles, thereby improving the sulfidation resistance of the conductive film.

  FIG. 1 is a partial plan view of a flexible printed board, and FIG. 2 is a conceptual diagram showing a chemical structure of a conductive film in the present embodiment.

  A flexible printed circuit board 1 shown in FIG. 1 is formed by forming a conductive film (conductive pattern) 3 on a flexible insulating substrate 2 such as a polyester resin such as polyethylene terephthalate or a polyimide resin by a printing method or the like.

  In the present embodiment, the conductive film 3 includes conductive particles having silver particles and / or copper particles and a triazine thiol derivative.

  The triazine thiol derivative is represented by the following chemical formula [Chemical Formula 1] or [Chemical Formula 2].

Here, R ₁ and R ₂ are H, CH ₃ , C ₂ H ₅ , C ₄ H ₉ , C ₆ H ₁₃ , C ₈ H ₁₇ , C ₁₀ H ₂₁ , C ₁₂ H ₂₅ , and C ₁₈ H, respectively. _{37, C 20 H 41, C} 22 H 45, C 24 H 49, CF 3 C 6 H 4, C 4 F 9 C 5 H 4, C 6 F 13 C 5 H 4, C 8 F 17 C 6 H 4 , C ₁₀ F ₂₁ C ₆ H ₄ , C ₆ F ₁₁ C ₆ H ₄ , C ₉ F ₁₇ CH ₂ , C ₁₀ F ₂₁ CH ₂ , C ₄ F ₉ CH ₂ , C ₆ F ₁₃ CH ₂ CH ₂ , C _{8 F 17 CH 2 CH 2,} C 10 F 21 CH 2 CH 2, CH 2 = CHCH 2, CH 2 = CH (CH 2) 8, CH 2 = CH (CH 2) 9, C 8 H 17 CH 2 = _{C 8 H 16, C 6 H} 11, C 6 H 5 CH 2, C 6 H 5 CH 2 CH 2, CH 2 = CH (CH 2) 4 COOCH 2 CH 2, CH 2 = CH (CH 2) 8 COOCH ₂ CH ₂ , CH ₂ = CH (CH ₂ ) ₉ COOCH ₂ CH ₂ , C ₄ F _{9 CH = CHCH 2, C 6 F} 13 CH = CHCH 2, C 8 F 17 CH = CHCH 2, C 10 F 21 CH = CHCH 2, C 4 F 9 CH 2 CH (OH) CH 2, C 6 F 13 CH ₂ CH (OH) CH ₂ , C ₈ F ₁₇ CH ₂ CH (OH) CH ₂ , C ₁₀ F ₂₁ CH ₂ CH (OH) CH ₂ , CH ₂ = CH (CH ₂ ) ₄ COO (CH ₂ CH ₂ ) _{2, CH 2 = CH (CH} 2) 8 COO (CH 2 CH 2) 2, CH 2 = CH (CH 2) 9 COO (CH 2 CH 2) 2, C 4 F 9 COOCH 2 CH 2, C 6 F ₁₃ COOCH ₂ CH ₂ , C ₈ F ₁₇ COOCH ₂ CH ₂ , C ₁₀ F ₂₁ COOCH ₂ CH ₂ , (CF) ₁₇ CF ₃ may be the same or different. M1, M2, and M3 each represent H or an alkali metal, and may be the same or different.

  The triazine thiol derivative is considered to form a complex with conductive particles having silver particles and / or copper particles. FIG. 2 is a conceptual diagram of the chemical structure of the conductive film 3. As shown in FIG. 2, it is considered that the triazine thiol derivative is firmly bonded to the surface of the silver particles. It is possible to effectively improve the sulfidation resistance.

  As shown in FIG. 2, the triazine thiol derivative is considered to be bonded to the surface of the silver particle in a state where M1 and M2 are detached.

  The triazine thiol derivative preferably contains fluorine. Corrosion caused by hydrogen sulfide contributes to moisture. Therefore, by adding a triazine thiol derivative containing fluorine to the conductive film 3 to improve water repellency, the sulfide resistance can be improved more effectively. .

  In addition, when the chain length of R1 and R2 is longer (the number of carbon atoms is larger), the surface of the silver particle is effectively covered with the triazine thiol derivative, and the sulfur resistance can be improved more effectively. Conceivable.

  In this embodiment, particularly when silver particles are used, it is possible to effectively improve the sulfidation resistance. The conductive film 3 containing silver particles is preferable because the resistance value of the conductive film 3 can be appropriately reduced.

  The said triazine thiol derivative should just be contained about 0.01 mass%-5 mass%, when electroconductive particle is 100 mass%.

  The conductive film 3 may contain an organic substance such as a binder resin in addition to the conductive particles and the triazine thiol derivative.

  The conductive film 3 of this embodiment is formed as follows. First, a conductive ink is formed by containing a triazine thiol derivative in an aqueous solution or alcohol solution of conductive particles having silver particles and / or copper particles. The alcohol liquid is, for example, an ethanol liquid.

  For example, when the conductive film 3 is formed using a screen printing method, it is necessary to further contain a binder resin.

  Then, the conductive ink is applied by, for example, an inkjet method or a screen printing method, and the applied conductive ink is baked. Thereby, the electrically conductive film 3 which has electroconductive particle and a triazine thiol derivative (a binder resin is further contained in the said screen printing method) is completed.

  In the present embodiment, it is preferable to use an aqueous solution of the conductive particles and add a triazine thiol derivative of an alkali metal salt to the aqueous solution. In the above [Chemical Formula 1], an alkali metal is selected for M1 and / or M2. Thereby, it is considered that the triazine thiol derivative is effectively dissolved in the aqueous solution of the conductive particles to form a complex structure in which the triazine thiol derivative is appropriately bonded to the surface of the conductive particles. In addition, it is preferable to select Na for the alkali metal. In an experiment to be described later, it has been confirmed that the conductive film 3 formed by adding a triazine thiol derivative having Na to an aqueous solution having silver particles has effectively improved sulfide resistance.

  In this embodiment, the conductive ink is applied by an ink jet method or a screen printing method, and baked to form the conductive film 3. Since the conductive film 3 contains a triazine thiol derivative, the conductive film 3 is excellent in sulfidation resistance. Thus, the conductive film 3 having excellent sulfidation resistance is formed into a circuit pattern by the inkjet method or the screen printing method. It can be finely formed by using electrodes or electrodes.

(Comparative Example 1)
A conductive ink made of an ethanol solution containing silver particles was applied onto an OHP film and baked at 170 ° C. for 30 minutes.

(Comparative Example 2)
A conductive ink made of an aqueous solution containing silver particles was applied onto an OHP film and baked at 170 ° C. for 30 minutes.

Example 1
A conductive ink is produced by adding 0.5% by mass (when the silver particle is 100% by mass) of the triazinethiol derivative of [Chemical Formula 3] shown below to an ethanol liquid containing silver particles. It apply | coated on the OHP film and baked at 170 degreeC for 30 minutes.

(Example 2)
A conductive ink is produced by adding 0.5% by mass (when the silver particle is 100% by mass) of the triazinethiol derivative of [Chemical Formula 4] shown below to an aqueous solution containing silver particles. It was applied onto a film and baked at 170 ° C. for 30 minutes.

(Example 3)
A conductive ink is produced by adding 0.5% by mass (when the silver particle is 100% by mass) of the triazinethiol derivative of [Chemical Formula 5] shown below to an ethanol liquid containing silver particles, It apply | coated on the OHP film and baked at 170 degreeC for 30 minutes.

Example 4
A conductive ink is produced by adding 0.5% by mass (when the silver particle is 100% by mass) of the following [Chemical Formula 6] triazine thiol derivative to an aqueous solution containing silver particles. It was applied onto a film and baked at 170 ° C. for 30 minutes.

(Example 5)
A conductive ink is produced by adding 0.5% by mass (when the silver particle is 100% by mass) of the triazinethiol derivative of [Chemical Formula 7] shown below to an ethanol liquid containing silver particles, It apply | coated on the OHP film and baked at 170 degreeC for 30 minutes.

(Example 6)
A conductive ink is produced by adding 0.5% by mass of the triazine thiol derivative of [Chemical Formula 3] shown above (when the silver particle is 100% by mass) to an ethanol solution containing silver particles. It apply | coated on the OHP film and baked at 200 degreeC for 30 minutes.

  The conductive films of Comparative Examples 1 and 2 and the conductive films of Examples 1 to 6 contain 3 ppm of hydrogen sulfide in the atmosphere, have a humidity of 85 to 90%, and a temperature of 40 ° C. Sheet resistance was measured. After 48 hours, the humidity was set to 70 to 75%. The experimental results are shown in FIG.

  It was found that all of Examples 1 to 6 had a lower sheet resistance and improved resistance to sulfidation compared to Comparative Examples 1 and 2.

  From the experimental results shown in FIG. 3, it was found that, in particular, Examples 2, 4 and 6 have low sheet resistance and excellent sulfidation resistance.

  In each of Example 2 and Example 4, a triazine thiol derivative of Na salt was added to an aqueous solution containing silver particles, whereby the triazine thiol derivative was effectively dissolved in the aqueous solution, and the silver It is considered that the particles and the triazine thiol derivative are appropriately reacted. On the other hand, in Examples 1, 3, and 5, an ethanol solution containing silver particles is used. In the case of an ethanol solution, as shown in [Chemical Formula 3], [Chemical Formula 5], and [Chemical Formula 7], the triazine thiol derivative is easily dissolved in the ethanol solution by using SH, but it still reacts sufficiently. I knew it was n’t there.

  Also, in Example 6, unlike Example 1, the conductive film was formed by raising the firing temperature to 200 ° C. It is considered that by increasing the firing temperature, the triazine thiol derivative is activated and effectively reacts with the silver particles. Therefore, even when an ethanol liquid is used as the conductive ink, the sheet resistance can be lowered and sufficient sulfidation resistance can be obtained by increasing the firing temperature.

  Moreover, in Example 3, although sheet resistance became high compared with Example 2, 4, and 6, it turned out that sheet resistance is low compared with the other Example and sulfidation resistance is improving. This is presumably because Example 3 (same as Example 4) uses a triazine thiol derivative containing fluorine, which improves the water repellency of the conductive film.

Partial plan view of flexible printed circuit board, The conceptual diagram which shows the chemical structure of the electrically conductive film in this embodiment, The graph which shows the relationship between the elapsed time of each electrically conductive film, and sheet resistance, forming the electrically conductive film of Examples 1-6 (a triazine thiol derivative is included) and Comparative Examples 1 and 2 (a triazine thiol derivative is not included),

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flexible printed circuit board 2 Insulating board 3 Conductive film (conductive pattern)

Claims (5)

  A conductive film comprising conductive particles having silver particles and / or copper particles, and a triazine thiol derivative.   The conductive film according to claim 1, wherein the triazine thiol derivative contains fluorine. The manufacturing method of the electrically conductive film characterized by having the following processes.
(A) a step of forming a conductive ink containing a triazine thiol derivative in an aqueous solution or alcohol solution of conductive particles having silver particles and / or copper particles;
(B) A step of applying and baking the conductive ink on a substrate.   The manufacturing method of the electrically conductive film of Claim 3 which adds the triazine thiol derivative of an alkali metal salt to the aqueous solution of the said electroconductive particle at the said (a) process.   The method for producing a conductive film according to claim 3 or 4, wherein the conductive ink is applied onto the substrate by inkjet or screen printing.

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