JP2943362B2 - Electrically conductive ink and method for formation of electrically conductive thick film pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a conductive thick film pattern on a circuit board and a conductive ink used for the method.

[0002]

2. Description of the Related Art Conventionally, screen printing has been used as the most common method of forming a thick film pattern on a circuit board, but the pattern width which can be mass-produced as an industrial product is 100 μm.
Is the limit. Ikegami reported that a pattern width of 30 μm was possible by changing the screen mesh.
Goto and Tokumaru, "Electronic Materials; May 1989, P4
4: Patterning technology in hybrid microelectronics ”, but it is still at the laboratory level.

[0003] Some conductive pastes for screen printing, which are commercially available as conductive pastes, contain an ethylcellulose resin or an acrylic resin in a binder, and the ink has a high viscosity and cannot be used for offset printing as it is.

[0004]

The reason why the pattern width which can be mass-produced as an industrial product by screen printing is limited to 100 μm is because the mesh-shaped screen is used, and the linearity of the pattern is hindered or lacked by the influence of the mesh. Due to disconnection, the pattern width that can be mass-produced as an industrial product by screen printing is limited to 100 μm.

On the other hand, Japanese Patent Publication No. 55-36
At 512, a thick film printing method by offset printing is shown. However, here, the rubber hardness of the soft substance is 30 degrees or less, and it is difficult to faithfully reproduce the pattern with a fine pattern having a pitch of 100 μm or less.

Some screen printing pastes commercially available as conductive pastes contain an ethylcellulose resin or an acrylic resin in a vehicle.
In Japanese Patent Application Laid-Open No. 2-228375, an acrylic resin having a molecular weight of 50,000 to 500,000 is used as an organic binder for a thick film paste in Examples. However, such inks have high viscosity and cannot be used for offset printing. There is a method of increasing the amount of resin in order to increase the transfer amount and improve the printing characteristics. However, in order to increase the amount of the high molecular weight resin while maintaining the printing characteristics, the amount of the solvent must also be increased, and there is a problem that the pigment concentration in the ink decreases and the ink density becomes low. further,
Simply increasing the content of the resin deteriorates the scattering properties of the resin, and the binder does not completely scatter during firing and remains as carbon particles, which greatly affects the resistance value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a high-quality fine pattern with excellent edge linearity and little occurrence of skein, chipping, etc., and particularly, a pattern width of 100 μm.
An object of the present invention is to provide a conductive thick film pattern forming method for mass-producing conductive thick film pattern products using offset printing in order to obtain the following fine patterns.

Another object of the present invention is to provide a conductive ink suitable for the above-mentioned pattern forming method.

[0009]

In order to solve the above-mentioned problems, a method for forming a conductive thick film pattern according to the present invention comprises the steps of: filling conductive ink into a concave portion of an intaglio; Transferring onto a blanket surface-coated with an elastic body mainly composed of silicone resin, transferring and printing the conductive thick film pattern transferred on the blanket onto a substrate, and transferring the transferred conductive thick film pattern. And a step of sintering the transferred conductive thick film pattern.

Further, the conductive ink of the present invention comprises a conductive metal powder, a glass frit, a transition metal oxide, and a dispersant, polyiso-butyl methacrylate (i-BMA),
An organic binder composed of at least one of iso-propyl methacrylate (i-PMA), polymethyl methacrylate (MMA), polytetrafluoroethylene, or poly-α-methylstyrene (α-MeSt), or poly -Copolymer of α-methylstyrene and polyiso-butyl methacrylate, poly-α-methylstyrene, polyiso-
Of butyl methacrylate and polymethyl methacrylate copolymer, poly-α-methyl styrene and poly iso-propyl methacrylate copolymer, poly-α-methyl styrene, poly iso-propyl methacrylate and polymethyl methacrylate copolymer It is composed of a vehicle containing at least one or more as an organic binder. It is preferable to use at least one of copper, gold, and silver as the conductive metal powder. The organic binder preferably has a weight average molecular weight of 100,000 to 1,300. The amount of the organic binder is preferably 2 to 15% by weight based on the whole ink.

Further, considering the adhesive strength of the thick film pattern to the substrate, the amount of the transition metal oxide in the ink is 0.5 to 2.0% by weight based on the total amount of the ink. The glass frit amount is 3 to 4 with respect to the total ink amount.
Weight% values are preferred. In consideration of the adhesive strength of the thick film pattern to the substrate, the amount of the dispersant is preferably 0.05 to 5.0% by weight based on the total amount of the ink.
When the linearity of the print pattern is considered, the amount of the organic solvent constituting the vehicle is 0.04 to 0.04 to the total amount of the powder.
0.18 is preferred.

[0012]

According to the present invention, the ink composition suitable for offset printing can be prepared by the above-described structure, and a high-definition pattern can be easily formed on a circuit board by offset printing. This is effective in that a fine pattern with excellent linearity and little occurrence of skein, chipping or the like can be formed, and a high-quality pattern can be obtained in terms of accuracy.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment relating to a method for forming a conductive thick film pattern of the present invention and a conductive ink will be described.
This will be described with reference to the drawings.

FIG. 1 (a) is a sectional view of a method for filling the intaglio with ink. (FIG. 1 (a))
1 is an intaglio. First, the conductive ink 102 is intaglio 1
No. 01, the entire surface of the intaglio is scraped off with a scraper 103, and ink is left only in the recesses.

FIG. 1 (b) is a cross-sectional view of a method of transferring a pattern from an intaglio to a blanket. In FIG. 1 (b), reference numeral 202 denotes a blanket whose surface is covered with a rubber-like elastic material having good releasability. The blanket is made of, for example, silicone resin, fluorine resin, polyethylene resin, etc.
~ 60 degrees (the hardness in the present invention is all JIS K-63
Depends on form 01,5-2, A. ) May be coated with a surface having a thickness of about 5 mm. Reference numeral 203 denotes a pattern formed on the blanket by pressing the blanket 202 against the intaglio 101.

FIG. 1 (c) is a cross-sectional view of a method for press-transferring a pattern on a blanket to a substrate. 302
Is a desired pattern obtained by pressure-transferring a pattern on a blanket onto a substrate. The transfer pressure in the step of transferring the ink in the recesses of the intaglio onto the blanket and the printing pressure in the step of transferring and printing the conductive thick film pattern transferred on the blanket onto the substrate are 2 to 6 kg.
/ Cm ² .

When a desired pattern is formed on a substrate by the steps shown in FIGS. 1 (a) to 1 (c), the solvent contained in the thick film composition is removed by evaporation. Is dried at 100 to 150 ° C. for 10 minutes. Subsequently, firing and sintering are performed at the highest temperature for 10 minutes.
The electric furnace is programmed such that the total firing time is 60 minutes.

When the conductive metal powder is oxidized at the time of firing, firing is performed in a non-oxidizing atmosphere step so that the oxygen concentration is 1%.
It is 0 ppm or less, and the firing temperature is 850 to 975 ° C. The firing temperature in the oxidizing atmosphere process is 8
50-975 ° C.

Further, the conductive ink comprises a conductive metal powder,
Glass frit, a transition metal oxide, and a dispersant, polyiso-butyl methacrylate, polyiso-propyl methacrylate, polymethyl methacrylate, polytetrafluoroethylene, or at least one of poly-α-methylstyrene And a vehicle containing an organic binder. Further, the organic binder is a copolymer of poly-α-methylstyrene and polyiso-butyl methacrylate, preferably 5 to 20% by weight of poly-α-methylstyrene and 80 to 95% by weight of polyiso-butyl methacrylate. Or a copolymer of poly-α-methylstyrene, polyiso-butyl methacrylate and polymethyl methacrylate, preferably 5 to 20% by weight of poly-α-methylstyrene, polyisocyanate
A copolymer consisting of 55 to 75 % by weight of o-butyl methacrylate and 20 to 25% by weight of polymethyl methacrylate, or a copolymer of poly-α-methylstyrene and polyiso-propyl methacrylate, preferably poly-α
A copolymer consisting of 5 to 20% by weight of methylstyrene and 80 to 95% by weight of poly iso-propyl methacrylate, or a copolymer of poly-α-methyl styrene, poly iso-propyl methacrylate and polymethyl methacrylate , Preferably poly-α-methylstyrene 5-
20% by weight, poly iso-propyl methacrylate 55-55
It is composed of a copolymer having a ratio of 75 % by weight and 20 to 25% by weight of polymethyl methacrylate.

It is preferable to use at least one of copper, gold and silver as the conductive metal powder.

The transition metal oxide in the ink is preferably composed of at least one of zinc oxide, titanium oxide, chromic oxide, cadmium oxide and nickel monoxide. The organic solvent constituting the vehicle is α-terpineol, butyl carbitol,
Butyl carbitol acetate, 2,2,4-trimethyl 1-3
It is preferable to be composed of at least one of hydroxypentyl isobutyrate, 2-butoxyethanol and 2-ethoxyethanol.

The conductive ink has an organic solvent content of 3 to 13% by weight and a glass frit content of 3% by weight.
~ 4 wt%, transition metal oxide 0.5 ~ 2.0 wt%,
The dispersant is 0.05 to 5.0% by weight, and the conductive metal powder is 7%.
Preferably, it comprises a value of from 8 to 86% by weight. The average particle size of the conductive metal powder is 0.05 to 3.0 μm.
It is preferred that

Hereinafter, a specific description will be given using an embodiment. Example 1 Using a three-roll ceramic roll, a mill base having the following composition was passed through the mill six times to prepare a copper ink.

Copper (average particle size: 1.0 μm) 79 (parts by weight) Glass frit (GA-9, manufactured by Nippon Electric Glass Co., Ltd.) 3 Zinc oxide (manufactured by Kanto Chemical Co., Ltd.) 1 ・ i-BMA, α-MeSt resin (manufactured by Sekisui Chemical Co., Ltd., IBS-6) ・ ・ 10 Weight average molecular weight 4750 ・ Solvent (manufactured by Kanto Chemical Co., Ltd., butyl carbitol acetate) ・ ・ 6.6 ・Dispersant (phosphate ester of polyoxyethylene alkyl (or alkyl aryl 0.4)) Using the copper ink described above, a 85, 6
A pattern of 0, 42, 34, 18 μm and a height of 4 μm was printed. The printing method will be described below. Intaglio is 100,7 width
Using a pattern obtained by etching a pattern of 5, 50, 40, 30 μm and a plate depth of 13.5 μm on glass, the copper ink was dropped on the intaglio, and the entire surface of the intaglio was scraped off with a ceramic scraper. The copper ink is left only in the concave portions, and silicone rubber (JIS K-6301, 5-2,
A blanket having a thickness of 5 mm and a thickness of 35 mm (A type rubber hardness) was pressure-bonded and rotated to transfer a pattern onto the blanket. The printing pressure at this time is 5 kg / cm
² went. Further, the blanket on which the pattern was formed was pressed against the object to be transferred and rotated to transfer the pattern onto the object to be transferred. The resulting pattern has good linearity,
It was of high quality with no invisibility or chipping.

If the hardness of the silicone rubber covering the blanket is very low, as in tampo printing, (1)
(Less than 0 degrees), the deformation amount of the rubber-like elastic body became large, and faithful reproduction of the intaglio pattern could not be performed. If it was too hard, the contact between the blanket and the ink became poor, and the faithful pattern could not be reproduced. The hardness of the elastic body for surface coating is 20 degrees or more of JIS rubber hardness, preferably 30 to 6 degrees.
Rubber hardness in the range of 0 degrees was optimal. When the printing pressure is low (2 kg / cm ² or less), the amount of ink transferred to the blanket is small, and when the printing pressure is high (6 kg / cm ² ).
(Kg / cm ² or more), the amount of deformation of the rubber-like elastic body was large, and faithful reproduction of the intaglio pattern was not possible. As the printing pressure, a pressure in the range of ^{2 to} 6 kg / cm ² was optimal.

Example 2 Using three ceramic rolls,
The mixture was passed through a mill base having the following composition six times to prepare a copper ink.

Copper (average particle size 2.0 μm) 79 (parts by weight) Glass frit (GA-9, manufactured by Nippon Electric Glass Co., Ltd.) 3 Zinc oxide (manufactured by Kanto Chemical Co., Ltd.) 1 ・ i-BMA, α-MeSt, MMA resin (manufactured by Sekisui Chemical Co., Ltd., 7.5 IBS-3) weight average molecular weight 87340 ・ Solvent (manufactured by Kanto Chemical Co., Ltd., butyl carbitol acetate) 9.1 Dispersant (phosphate ester of polyoxyethylene alkyl (or alkyl 0.4 alkyl allyl)) On the alumina substrate by the same gravure offset method as in Example 1 using the same intaglio as in Example 1. Was printed with a copper fine pattern. The printed pattern is linear,
The film thickness accuracy was good. Subsequently, the copper thick film pattern printed on the substrate was dried at 120 ° C. for 10 minutes to remove the solvent contained in the thick film composition by evaporation. Further, using nitrogen, in a non-oxidizing atmosphere having an oxygen concentration of 10 ppm or less so that copper is not oxidized, firing in an electric furnace in which the temperature of the high-temperature holding unit is maintained at 920 ° C. in order to completely burn off the organic binder. Was done. The firing conditions were set so that the required time at the highest temperature part was 10 minutes and the total firing time was 60 minutes. As a result, the organic polymer contained in order to maintain printability was decomposed with an increase in temperature, and a copper thick film pattern having excellent edge linearity and less occurrence of scars and chips could be obtained. Further, it was able to withstand the peeling test, and had a sheet resistance value of 8 to 15 mΩ / □.

(FIG. 2) shows the first embodiment and the second embodiment.
When the amount of the organic binder of the copper ink used in was changed, the weight percentage of the organic binder with respect to the total amount of the ink,
4 is a graph showing curves 401 and 402 showing a transfer amount curve (weight ratio of the amount of the ink transferred to the blanket to the amount of the ink filled in the concave portions of the intaglio) of the transfer amount of the copper ink to the transfer object. At this time, the region where the amount of transfer was large was in the range of 2 to 15% by weight of the organic binder, and the region where the amount of transfer was the largest was in the range of 2 to 10% by weight of the organic binder.

FIG. 3 shows the weight average molecular weight of the organic binder and the curve of the transfer amount of the copper ink to the object (the weight ratio of the amount of the ink transferred to the blanket to the amount of the ink filled in the recesses of the intaglio). 3) shows a graph representing 301.
At this time, the region with a large amount of transfer has a weight average molecular weight of the organic binder in the range of 1300 to 100,000, and the region with the largest amount of transfer has a weight average molecular weight of the organic binder of 1300 to 4
Was in the range of 10,000.

Although the figure shows only the case where the conductive metal powder is copper, similar results were obtained with other conductive metal powders.

Example 3 Using a three ceramic roll, a mill base having the following composition was passed through the mill six times to prepare a gold ink.

Gold (average particle size: 1.0 μm) 79 (parts by weight) Glass frit (GA-9, manufactured by Nippon Electric Glass Co., Ltd.) 3 Zinc oxide (manufactured by Kanto Chemical Co., Ltd.) 1 i-PMA, α-MeSt resin (B-12, manufactured by Sekisui Chemical Co., Ltd.) 9 Weight average molecular weight 1306 Solvent (butyl carbitol acetate, manufactured by Kanto Chemical Co., Ltd.) 7.6 Dispersant (phosphate ester of polyoxyethylene alkyl (or alkyl 0.4 alkyl allyl)) Using the above gold ink and the same intaglio as in Example 1, by the same gravure offset method as in Example 1. ,
85,60,42,34,18μ width on alumina substrate
m, a pattern having a height of 4 μm was printed. The obtained pattern had good linearity and was of high quality without any invisibility or chipping. Further, a gold thick film pattern was obtained under the same non-oxidizing atmosphere and firing conditions as in Example 2. The sheet resistance was able to withstand the peeling test, and the sheet resistance was 11 to 21 mΩ / □.

Example 4 Using the same intaglio as in Example 1, a gold fine pattern was printed on an alumina substrate by the same gravure offset method as in Example 1 using the same gold ink as in Example 3. The printed pattern was good in both linearity and film thickness accuracy. Subsequently, the gold thick film pattern printed on the substrate was dried at 120 ° C. for 10 minutes to remove the solvent contained in the thick film composition by evaporation. Further, firing was performed in an electric furnace in which the temperature of the high-temperature holding section was maintained at 850 ° C. in air. The firing conditions were set so that the required time at the highest temperature part was 10 minutes and the total firing time was 60 minutes. As a result, the organic polymer contained in order to make it printable was decomposed with an increase in temperature, and a gold thick film pattern with excellent edge linearity and less occurrence of scars, chips, etc. could be obtained. In addition, it can withstand a peeling test, and has the same degree as 13 to 13 when fired in a non-oxidizing atmosphere.
The sheet resistance was 22 mΩ / □.

Example 5 Using a three ceramic roll,
The mixture was milled through a mill base having the following composition six times to prepare a silver ink.

Silver (average particle size 2.0 μm) 79 (parts by weight) Glass frit (GA-9, manufactured by Nippon Electric Glass Co., Ltd.) 3 Zinc oxide (manufactured by Kanto Chemical Co., Ltd.) 1 ・ i-BMA, α-MeSt, MMA resin (manufactured by Sekisui Chemical Co., Ltd.,... 10 IBM7L-3) weight average molecular weight 32060 ・ Solvent (manufactured by Kanto Chemical Co., Ltd., butyl carbitol acetate) ・ ・ 6. 6-Dispersant (phosphate ester of polyoxyethylene alkyl (or alkyl 0.4 alkyl allyl)) Using the same intaglio as in Example 1, a gravure offset method similar to that in Example 1 was used to form a width on an alumina substrate. 85,6
A silver fine pattern of 0, 42, 34, 18 μm and a height of 3 μm was printed. The printed pattern was good in both linearity and film thickness accuracy. Subsequently, the silver thick film pattern printed on the substrate was sintered under the same non-oxidizing atmosphere conditions as in Example 2. As a result, the organic polymer contained in order to make it printable was decomposed with an increase in temperature, and a silver thick film pattern having excellent edge linearity and less occurrence of scars and chips could be obtained. Further, the sheet resistance was able to withstand the peeling test, and the sheet resistance was 7.5 to 14.5 mΩ / □.

Example 6 Using the same intaglio as in Example 1, using the same silver ink as in Example 5, and using the same gravure offset method as in Example 1,
A silver fine pattern was printed on an alumina substrate. Further, drying and firing were performed under the same conditions as in Example 4.

As a result, it is possible to obtain a silver thick film pattern which is excellent in linearity of the edge and has few occurrences of skein, chipping, etc., by decomposing the organic polymer contained for imparting printability with increasing temperature. done. Further, the sheet resistance was able to withstand the peeling test, and the sheet resistance value was about 10 to 16 mΩ / □, which was almost the same as that when baked in a non-oxidizing atmosphere.

Example 7 A three-roll ceramic roll was used to pass through a mill base having the following composition six times to prepare a copper ink.

Copper (average particle size: 0.05 μm) 79 (parts by weight) Glass frit (GA-9, manufactured by Nippon Electric Glass Co., Ltd.) 3 Zinc oxide (manufactured by Kanto Chemical Co., Ltd.) 1 ・ i-BMA, α-MeSt resin (manufactured by Sekisui Chemical Co., Ltd., IBS-6) ・ ・ 8 Weight average molecular weight 4750 ・ Solvent (manufactured by Kanto Chemical Co., Ltd., butyl carbitol acetate) ・ ・ 8.6 Dispersant (phosphate ester of polyoxyethylene alkyl (or alkyl 0.4 alkyl allyl)) Using the same intaglio as in Example 1, a gravure offset method similar to that of Example 1 was used to form a copper fine pattern on an alumina substrate. Was printed. Subsequently, baking was performed under the same conditions as in Example 2. As a result, it was possible to obtain a copper thick film pattern which was excellent in the linearity of the edge and in which there were few occurrences of scars and chips. In addition, it can withstand the peeling test,
The sheet resistance was 3 mΩ / □. By using a powder having a small average particle size, the sheet resistance value is reduced. Example 7 shows an example of copper powder, but gold, silver powder,
And mixtures are no problem.

In Examples 1 and 7, poly-iso-butyl methacrylate (i-BMA) and poly-α-
Using a copolymer of methylstyrene (α-MeSt), polyiso-butyl methacrylate (i
-BMA), a copolymer of poly-α-methylstyrene (α-MeSt) and polymethyl methacrylate (MMA), and polyiso-propyl methacrylate (i-PMA) Although the copolymerized product of α-methylstyrene (α-MeSt) was used, it may be used alone or a copolymerized product may be mixed.

Further, poly-iso-propyl methacrylate (i-PMA), polytetrafluoroethylene, poly-iso-propyl methacrylate (i-PMA), poly-α-methylstyrene (α-MeSt) and polymethyl methacrylate (MMA)
It is also possible to use a copolymerized product of the above. Of course, this is because the compatibility between the resins and the amount of the resin dissolved in the solvent are taken into consideration. However, ordinary general acrylic resins (for example, poly n-butyl methacrylate) have poor scattering properties and cannot be used. In order to further improve the pigment dispersion, glycidyl methacrylate or the like copolymerized within 5% can be used. However, at least 5-2
It was necessary to contain 0% by weight of α-methylstyrene, and if the area exceeded this range, or the acrylic resin alone was used, the resin was not easily dispersed, and the formed conductive thick film pattern had a high sheet resistance. When polymethyl methacrylate is used as the acrylic resin, 20 to 2
Desirably, it is 5% by weight. In a region exceeding this range, the printability of the ink is poor, and the scattering property of the resin is also poor. In addition, when the average molecular weight of the resin is 100,000 or more, the viscosity of the ink becomes high and the ink becomes unsuitable for printing.
If it is less than 0, the scattering property at the time of firing deteriorates. That is, the average molecular weight of the resin was preferably 100,000 to 1300, and the most preferable average molecular weight was 40,000 to 1300 as shown in FIG. When the content of the resin is 15% by weight or more with respect to the whole ink, the ink viscosity becomes high and becomes unsuitable for printing, and when it is less than 2% by weight, the ink viscosity becomes low and it becomes unsuitable for printing. That is, the content of the resin is preferably 2 to 15% by weight based on the whole ink, and most preferably the content is 2 to 10% by weight based on the whole ink as shown in FIG. .

Examples 1, 2, 7 as the conductive metal powder
Although copper was used in Examples 3 and 4 and gold was used in Examples 3 and 4, silver was used in Examples 5 and 6. However, the present invention is not limited thereto. Copper powder was used in Examples 3 and 5, and gold powder was used in Examples 1 and 2. 2,5,6,7
Thus, silver powder may be used in Examples 1, 2, 3, 4, and 7, or a mixture of conductive metal powder may be used.

The content of these conductive metal powders is preferably 78 to 86% by weight based on the whole ink. If it is smaller than this range, the thick film after firing is not dense. If it is larger than this range, the viscosity of the ink increases, which is unsuitable for printing. Further, the average particle size of the conductive metal powder is preferably 0.05 to 3.0 μm. 0.
When the average particle size is smaller than 05 μm, the surface area of the whole particles becomes large and the amount of the vehicle in the ink must be increased, and the content of the conductive metal decreases. 3.0
When it is larger than μm, there is a problem that the sheet resistance value becomes large because the firing is not performed densely.

In Examples 1, 2, 3, 4, 5, 6, and 7, butyl carbitol acetate was used as the organic solvent constituting the vehicle. However, the present invention is not limited to these, and α-terpineol, butyl Carbitol, 2,
2,4-trimethyl 1-3-hydroxypentyl isobutyrate, 2-butoxyethanol, 2-ethoxyethanol,
Each of them may be used alone or in combination, and can be used according to printing conditions and drying conditions.

The transition metal oxides of Examples 1 and 2
Zinc oxide was used in 2,3,4,5,6,7, but is not limited to these, and titanium oxide, chromic oxide, cadmium oxide, and nickel monoxide may be used alone or as a mixture. It may be used in accordance with printing conditions and drying conditions. When the content of the transition metal oxide was less than 0.5% by weight with respect to the total amount of the ink, the adhesive strength of the fired thick film to the substrate was low, and the film was peeled off even when a slight external force was applied. The preferred content is 0.5 to 2.0% by weight based on the total amount of the ink, and at this time, the result is that the film sufficiently withstands the peeling test.

The glass frit amount is preferably 3 to 4% by weight based on the total amount of the ink. If it is less than 3% by weight,
The adhesive strength of the fired thick film to the substrate was low, and the film was peeled off even when a slight external force was applied.

When the amount of the dispersant is less than 0.05% by weight based on the total amount of the ink, the storage stability is poor due to poor dispersibility of the ink. The amount remaining in the sheet increased, and the sheet resistance increased. That is, the content of the dispersant is desirably 0.05 to 5.0% by weight based on the whole ink.

In the firing in a non-oxidizing atmosphere, when the oxygen concentration is 10 ppm or more, the effect of oxygen is large in the process of scattering organic substances, and the residual carbon and the residual oxygen concentration in the conductive thick film are oxidizing. It was the same level as firing in the atmosphere. Therefore, when the oxygen concentration is 10 ppm or more,
The sheet resistance value becomes the same value as firing in an oxidizing atmosphere,
The sheet resistance was increased by about 2 mΩ / □ as compared with the sheet resistance when the oxygen concentration was 10 ppm or less. That is, it is desirable that the oxygen concentration be 10 ppm or less when firing in a non-oxidizing atmosphere. Furthermore, since the baking of the copper ink is usually performed in a non-oxidizing atmosphere, the silver or gold ink of the present invention and the copper ink can coexist in a non-oxidizing atmosphere.

[0049]

As described above, the present invention is characterized in that a printing pattern is formed by using offset printing, and that organic substances are scattered by firing in a non-oxidizing atmosphere or an oxidizing atmosphere. It is superior to the conventional screen printing method in terms of edge linearity and enables formation of fine patterns with less occurrence of skein, chipping, etc., and conductive metal powder, glass frit, transition metal oxide, dispersion This is effective in that it allows the preparation of a conductive ink suitable for the above printing method, which is composed of an agent and a vehicle containing an organic binder.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a method of filling an intaglio with an ink. (B) It is sectional drawing of the transfer method of the pattern from an intaglio to a blanket. (C) It is sectional drawing of the press-fitting transfer method of the pattern on a blanket to a board | substrate.

FIG. 2 is a graph showing a curve of an organic binder weight percentage with respect to a total ink amount and a transfer amount curve of a copper ink to a transfer body in Example 1 and Example 2.

FIG. 3 is a graph showing a curve of a weight average molecular weight of an organic binder and a transfer amount curve of a copper ink to a transfer object.

[Explanation of symbols]

 Reference Signs List 101 Intaglio 102 Conductive ink 103 Scraper 202 Blanket 203 Pattern formed on blanket 301 Substrate 302 Pattern transferred onto substrate 401 Transfer amount curve of Example 1 402 Transfer amount curve of Example 2 501 Transfer amount curve

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09D 11/10 H05K 1/09 H01B 1/16

Claims (18)

(57) [Claims] 1. A conductive metal powder, a glass frit, a transition metal oxide, and a dispersant, and poly-α-methylstyrene.
Copolymer of polyiso-butyl methacrylate and poly
-Α-methylstyrene and polyiso-butyl methacrylate
Copolymer of polymethyl methacrylate and poly-α-
Methyl styrene and poly iso-propyl methacrylate
Copolymer, poly-α-methylstyrene and polyiso-pro
Co-polymerization of pill methacrylate and polymethyl methacrylate
Composed of at least one of
A conductive ink comprising a vehicle containing an organic binder having a weight average molecular weight of 100,000 to 1,300 . 2. The conductive ink according to claim 1, wherein the poly-α-methylstyrene is a copolymer having a ratio of 5 to 20% by weight and polyiso-butyl methacrylate in a ratio of 80 to 95% by weight. 3. A copolymer comprising 5 to 20% by weight of poly-α-methylstyrene, 55 to 75% by weight of polyiso-butyl methacrylate, and 20 to 25% by weight of polymethyl methacrylate. The conductive ink according to claim 1 . 4. A poly-α-methylstyrene content of 5 to 20% by weight and a polyiso-propyl methacrylate content of 80 to 95%.
Conductive ink of claim 1, wherein comprised of a copolymer consisting by weight percent ratio. 5. The poly-α-methylstyrene content of 5 to 20% by weight and the polyiso-propyl methacrylate content of 55 to 75%.
% By weight, 20 to 25% by weight of polymethyl methacrylate
The conductive ink according to claim 1 , wherein the conductive ink is composed of a copolymer having the following ratio: 6. The amount of the organic solvent constituting the vehicle is 3 to 1
3% by weight, glass frit amount 3-4% by weight, transition metal oxide 0.5-2.0% by weight, dispersant 0.05-2.0%
The conductive ink according to claim 1, wherein 5.0% by weight and the conductive metal powder are 78 to 86% by weight. 7. The conductive ink according to claim 1, wherein the content of the organic binder is 2 to 15% by weight based on the whole ink. 8. The vehicle according to claim 1, wherein the amount of the organic solvent constituting the vehicle is 0.04 to 0.18 by weight based on the total amount of the powder.
The conductive ink according to the above. 9. The conductive ink according to claim 1, wherein the conductive metal powder comprises at least one of copper, gold, and silver. 10. The conductive metal powder has an average particle size of 0.05.
The conductive ink according to claim 1, which has a thickness of from 3.0 to 3.0 m. 11. The organic solvent constituting the vehicle is α-terpineol, butyl carbitol, butyl carbitol acetate, 2,2,4-trimethyl 1-3-hydroxypentyl isobutyrate, 2-butoxyethanol, 2-ethoxy 2. The conductive ink according to claim 1, comprising at least one of ethanol. 12. The conductive ink according to claim 1, wherein the transition metal oxide comprises at least one of zinc oxide, titanium oxide, chromic oxide, cadmium oxide, and nickel monoxide. 13. A step of filling the concave portion of the intaglio with the conductive ink according to any one of claims 1 to 12, wherein the conductive ink in the concave portion of the intaglio is converted into an elastic body mainly composed of silicone resin. Transferring a conductive thick film pattern transferred onto the blanket onto a substrate, printing the conductive thick film pattern onto the substrate, baking the conductive pattern to disperse organic matter, and firing the conductive pattern. Forming a conductive thick film pattern. 14. The method of claim 13 in which the hardness of the elastic body composed mainly of silicone resin, characterized in that 30 to 60 degrees
A method for forming a conductive thick film pattern according to the above. 15. A transfer pressure in a step of transferring ink in a concave portion of an intaglio onto a blanket whose surface is covered with an elastic body mainly composed of a silicone resin, and a conductive thick film pattern transferred on the blanket is used as a substrate. 14. The method for forming a conductive thick film pattern according to claim 13, wherein the printing pressure in the step of transferring and printing on the upper surface is ² to 6 kg / cm < ² >. 16. The method for forming a conductive thick film pattern according to claim 13, wherein the oxygen concentration in the non-oxidizing atmosphere baking step is 10 ppm or less. 17. The method for forming a conductive thick film pattern according to claim 13 , wherein the temperature of the high-temperature holding portion in the non-oxidizing atmosphere firing step is 850 to 975 ° C. 18. The temperature of the high-temperature holding portion in the oxidizing atmosphere firing step is 800 to 925 ° C.
14. The method for forming a conductive thick film pattern according to claim 13 .