JPH04213373A - Electrically conductive ink and method for formation of electrically conductive thick film pattern - Google Patents

Abstract

PURPOSE:To provide a method for forming an electrically conductive thick film pattern for obtaining a tune pattern and an electrically conductive ink suitable for this method. CONSTITUTION:A pattern 302 is formed by filling an electrically conductive ink 102 in recessed parts of an lntaglio 101, transferring it onto a blanket 202, and performing transfer printing on a base sheet 301. The electrically conductive ink is constituted of an electrically conductive metal powder, a glass frit, a transition metal oxide, a dispersing agent and a vehicle wherein at least one compd. selected from poly-iso-butyl methacrylate, poly-iso-propyl methacrylate, polymethyl methacrylate, polytetrafluoroethylene and poly-alpha-methylstyrene are incorporated as an org. binder.

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 therein.

0002

2. Description of the Related Art Screen printing has conventionally been used as the most common method for forming thick film patterns on circuit boards, but the pattern width that can be mass-produced as an industrial product is limited to 100 μm. Ikegami, Goto, and Tokumaru reported that a pattern width of 30 μm is possible by changing the mesh of the screen, published in "Electronic Materials; May 1989 issue, p. 44.
``Patterning Technology in Hybrid Microelectronics'', but it is still at the laboratory level.

[0003] Furthermore, some conductive pastes for screen printing that are commercially available as conductive pastes contain ethyl cellulose resin or acrylic resin as a binder, and the ink has a high viscosity and cannot be used as is for offset printing.

0004

[Problems to be Solved by the Invention] The reason why the pattern width that can be mass-produced as an industrial product by screen printing is limited to 100 μm is because a mesh-like screen is used, and the influence of the mesh hinders the linearity of the pattern and causes chipping. Because of the occurrence of wire breaks, the pattern width that can be mass-produced as an industrial product by screen printing is limited to 100 μm.

[0005] In contrast, Japanese Patent Publication 1985-36
At 512, a thick film printing method using offset printing is shown. However, here, the rubber hardness of the soft material is 30 degrees or less, and it is difficult to faithfully reproduce a fine pattern with a pitch of 100 μm or less.

[0006] Also, some screen printing pastes commercially available as conductive pastes contain ethyl cellulose resin or acrylic resin in the vehicle. In Japanese Patent Publication No. 2-228375, an acrylic resin having a molecular weight of 50,000 to 500,000 is used in the examples as an organic binder for thick film paste. However, such ink has a high viscosity and cannot be used as is for offset printing. In order to increase the amount of transfer and improve printing characteristics, there is a method of increasing the amount of resin. However, in order to increase the amount of high-molecular-weight resin while maintaining printing characteristics, the amount of solvent must also be increased, which poses a problem in that the pigment concentration in the ink decreases, resulting in a film with low ink density. moreover,
If the content of the resin is simply increased, the dispersibility of the resin will deteriorate, and the binder will not be completely dispersed during firing but will remain as carbon particles, which will greatly affect the resistance value.

The present invention is intended to solve the above-mentioned problems, and is intended to obtain a high-quality fine pattern with excellent edge linearity and less occurrence of scratches, chips, etc., especially a fine pattern with a pattern width of 100 μm or less. 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.

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

[0009]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the method for forming a conductive thick film pattern of the present invention includes a step of filling conductive ink into the recesses of an intaglio, and a step of filling the recesses of the intaglio with conductive ink. onto a blanket whose surface is coated with an elastic material mainly composed of silicone resin, a step of transfer-printing the conductive thick film pattern transferred onto the blanket onto a substrate, and a step of transfer-printing the transferred conductive thick film pattern. The process consists of a step of firing the organic matter to scatter the organic matter, and a step of sintering the transferred conductive thick film pattern.

Furthermore, the conductive ink of the present invention comprises conductive metal powder, glass frit, transition metal oxide, and dispersant, and polyiso-butyl methacrylate (i-BM).
A), polyiso-propyl methacrylate (i-P
MA), polymethyl methacrylate (MMA), polytetrafluoroethylene, or poly-α-methylstyrene (α-MeSt), or poly-α-methylstyrene and polyiso - Copolymer of butyl methacrylate, poly-α-methylstyrene, copolymer of polyiso-butyl methacrylate and polymethyl methacrylate, poly-α
- Copolymer of methylstyrene and polyiso-propyl methacrylate, poly-α-methylstyrene, polyiso
- It is composed of a vehicle containing at least one copolymer of propyl methacrylate and polymethyl methacrylate as an organic binder. As the conductive metal powder, it is preferable to use at least one of copper, gold, and silver. The organic binder preferably has a weight average molecular weight of 100,000 to 1,300. The amount of the organic binder is 2 for the entire ink.
Values of ˜15% by weight are preferred.

Furthermore, when considering the adhesive strength of the thick film pattern to the substrate, the amount of transition metal oxide in the ink is 0.5 to 2.0% by weight based on the total amount of the ink. The amount of glass frit is 3 to 4 based on the total amount of ink.
Values in % by weight are preferred. Further, when considering 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 considering the linearity of the printing pattern, the amount of organic solvent constituting the vehicle should be 0.04 to 0.04 by weight relative to the total amount of powder.
0.18 is preferred.

0012

[Function] With the above structure, the present invention makes it possible to prepare ink suitable for offset printing, and furthermore, by offset printing, high-definition patterns can be easily formed on circuit boards, and the edges can be formed more easily than by the conventional screen printing method. It is effective in that it has excellent linearity, enables the formation of fine patterns with little occurrence of scratches, chips, etc., and also provides high-quality patterns in terms of accuracy.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for forming a conductive thick film pattern and a conductive ink according to the present invention will be described below with reference to the drawings.

FIG. 1(a) is a sectional view showing a method of filling an intaglio plate with ink. (10 in Figure 1(a))
1 is an intaglio. First, conductive ink 102 is applied to the intaglio plate 1.
01, and the entire surface of the intaglio is scraped off with the scraper 103, leaving ink only in the recesses.

FIG. 1(b) is a sectional view of a method of transferring a pattern from an intaglio to a blanket. (Figure 1 (
In b)), 202 is a blanket whose surface is coated with a rubber-like elastic material having good mold releasability. For example, blankets are made of rubber that is mainly made of silicone resin, such as silicone resin, fluorocarbon resin, or polyethylene resin, and has a hardness of 30 to 30.
60 degrees (all hardness in this invention is JIS K-63
According to 01,5-2,A type. ) may be coated on the surface with a thickness of about 5 mm. 203 is 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 of pressure transfer of a pattern on a blanket onto a substrate. 302 is a desired pattern obtained by pressing and transferring the pattern on the blanket onto the 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 transfer printing the conductive thick film pattern transferred onto the blanket onto the substrate are 2 to 6 kg/
cm2.

From the above (Fig. 1(a)) to (Fig. 1(c)
After forming a desired pattern on a substrate by the process shown in ), drying is performed at 100 to 150° C. for 10 minutes when the solvent contained in the thick film composition is evaporated off. Next, the electric furnace is programmed so that the time required for firing and sintering at the highest temperature part is 10 minutes and the total firing time is 60 minutes.

If the conductive metal powder is oxidized during firing, the firing is performed in a non-oxidizing atmosphere process to reduce the oxygen concentration to 1.
It is 0 ppm or less, and the firing temperature is 850 to 975°C. In addition, the firing temperature in the oxidizing atmosphere process is 85
The temperature is 0 to 975°C.

Further, the conductive ink includes conductive metal powder,
It is composed of a glass frit, a transition metal oxide, a dispersant, and at least one of polyiso-butyl methacrylate, polyiso-propyl methacrylate, polymethyl methacrylate, polytetrafluoroethylene, or poly-α-methylstyrene. It consists of a vehicle containing an organic binder. Furthermore, the organic binder is a copolymer of poly-α-methylstyrene and polyiso-butyl methacrylate, preferably in a ratio of 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 poly-α-methylstyrene 5 to 20
Weight %, polyiso-butyl methacrylate 60-90
% by weight, a copolymer consisting of a ratio of 20 to 25% by weight of polymethyl methacrylate, or a copolymer of poly-α-methylstyrene and polyiso-propyl methacrylate,
Preferably 5 to 20% by weight of poly-α-methylstyrene,
Polyiso-propyl methacrylate 80-95% by weight
or a copolymer of poly-α-methylstyrene, polyiso-propyl methacrylate and polymethyl methacrylate, preferably poly-α-
- Consists of a copolymer consisting of a ratio of 5 to 20% by weight of methylstyrene, 60 to 90% by weight of polyisopropyl methacrylate, and 20 to 25% by weight of polymethyl methacrylate.

[0020] As the conductive metal powder, it is preferable to use at least one of copper, gold, and silver.

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,
It is preferably composed of at least one of butyl carbitol acetate, 2,2,4-trimethyl 1-3-hydroxypentyl isobutyrate, 2-butoxyethanol, and 2-ethoxyethanol.

Furthermore, the conductive ink has an organic solvent amount of 3 to 13% by weight constituting the vehicle and a glass frit amount of 3% by weight.
~4% by weight, 0.5-2.0% by weight of transition metal oxides,
Dispersant: 0.05-5.0% by weight, conductive metal powder: 7%
Preferably it consists of a value of 8 to 86% by weight. In addition, the average particle size of the conductive metal powder is 0.05 to 3.0 μm.
It is preferable that

A specific explanation will be given below using an example. Example 1 Using three ceramic rolls, a mill base having the composition shown below was passed through six times for kneading to prepare a copper ink.

・Copper (average particle size 1.0 μm)
・・79 (parts by weight) ・Glass frit (manufactured by Nippon Electric Glass Co., Ltd.,
GA-9) ... 3 - Zinc oxide (manufactured by Kanto Kagaku Co., Ltd.)
・・・ 1
・i-BMA, α-MeSt resin (manufactured by Sekisui Plastics Co., Ltd., IBS-6)...10
Weight average molecular weight 4750

・Solvent (manufactured by Kanto Kagaku Co., Ltd., butyl carbitol acetate) ・・6.6 ・Dispersant (polyoxyethylene alkyl (or alkyl ant) ・・
Using the above copper ink, print a width of 8 mm on an alumina substrate.
Patterns of 5, 60, 42, 34, and 18 μm and a height of 4 μm were printed. The printing method is shown below. The width of the intaglio is 10
0,75,50,40,30μm, plate depth 13.5μm
Using a glass with a pattern etched on the plate, drop the above copper ink onto the intaglio plate, scrape off the entire surface of the intaglio plate with a ceramic scraper, leave the copper ink only in the concave parts of the plate, and apply silicone rubber (JIS K- 6301,
5-2, type A (rubber hardness: 35 degrees)) A blanket whose surface was coated with a wall thickness of 5 mm was pressed and rotated to transfer the pattern onto the blanket. The printing pressure at this time is 5k
g/cm2. Furthermore, the pattern was transferred onto the transfer target by pressing the blanket on which the pattern was formed onto the transfer target and rotating the blanket. The obtained pattern was of high quality with good linearity and no scratches or chips.

If the hardness of the silicone rubber coating the surface of the blanket is very low, such as in pad printing, (1
(0 degree or less), the amount of deformation of the rubber-like elastic body becomes large, making it impossible to faithfully reproduce an intaglio pattern, and if it is too hard, the contact between the blanket and ink becomes poor, making it impossible to faithfully reproduce a pattern. The hardness of the elastic body for surface coating is JIS rubber hardness of 20 degrees or more, preferably 30 to 6.
A rubber hardness in the range of 0 degrees was optimal. Also, when the printing pressure is low (2 kg/cm2 or less), the amount of ink transferred to the blanket is small, and when the printing pressure is high (6 kg/cm2 or less), the amount of ink transferred to the blanket is small.
Kg/cm2 or more), the amount of deformation of the rubber-like elastic body becomes large, making it impossible to faithfully reproduce the intaglio pattern. The optimum printing pressure was in the range of 2 to 6 kg/cm2.

Example 2 Using three ceramic rolls,
A copper ink was prepared by passing through a mill base having the following composition six times and kneading it.

- Copper (average particle size 2.0 μm)
・・79 (parts by weight) ・Glass frit (manufactured by Nippon Electric Glass Co., Ltd.,
GA-9) ... 3 - Zinc oxide (manufactured by Kanto Kagaku Co., Ltd.)
・・・ 1
・i-BMA, α-MeSt, MMA resin (manufactured by Sekisui Plastics Co., Ltd., 7.5
IBS-3) Weight average molecular weight 87340 ・
Solvent (manufactured by Kanto Kagaku Co., Ltd., butyl carbitol acetate)...9.1 Dispersant (polyoxyethylene alkyl (or alkaline)...0.4
Phosphate ester of (kylarlyl)) Using the same intaglio plate as in Example 1, a copper fine pattern was printed on an alumina substrate by the same gravure offset method as in Example 1. The printed pattern had good linearity and film thickness accuracy. Subsequently, the copper thick film pattern printed on the substrate was dried at 120° C. for 10 minutes to evaporate and remove the solvent contained in the thick film composition. Further, baking is performed using nitrogen in a non-oxidizing atmosphere with an oxygen concentration of 10 ppm or less to prevent copper from being oxidized, and in an electric furnace with the temperature of the high temperature holding part maintained at 920°C to completely burn out the organic binder. I did it. The firing conditions were programmed so that the time required at the highest temperature part was 10 minutes and the total firing time was 60 minutes. As a result, the organic polymer contained in the material to make it suitable for printing decomposes as the temperature rises.
It was possible to obtain a copper thick film pattern with excellent edge straightness and less occurrence of scratches and chips. It was also able to withstand a peel test and had a sheet resistance value of 8 to 15 mΩ/□.

(Fig. 2) shows Example 1 and Example 2.
When the amount of organic binder in the copper ink used was changed, the weight percentage of the organic binder to the total amount of ink and the curve of the amount of copper ink transferred to the transfer object (the amount of ink transferred to the blanket, the concave part of the intaglio) 401 and 402 are shown. At this time, in the area where the amount of transfer was large, the organic binder weight percentage was in the range of 2 to 15% by weight, and in the area where the amount of transfer was the largest, the weight percentage of the organic binder was in the range of 2 to 10% by weight.

(Fig. 3) shows the weight average molecular weight of the organic binder and the curve of the amount of copper ink transferred to the object (the weight ratio of the amount of ink transferred to the blanket to the amount of ink filled in the recesses of the intaglio). ) 301 is shown. At this time, in the area where the amount of transfer is large, the weight average molecular weight of the organic binder is in the range of 1300 to 100,000, and in the area where the amount of transfer is the highest, the weight average molecular weight of the organic binder is 1300 to 4.
It was in the range of 10,000.

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

Example 3 Using three ceramic rolls, a mill base having the composition shown below was passed through six times for kneading to prepare gold ink.

・Gold (average particle size 1.0 μm)
・・79 (parts by weight) ・Glass frit (manufactured by Nippon Electric Glass Co., Ltd.,
GA-9) ... 3 - Zinc oxide (manufactured by Kanto Kagaku Co., Ltd.)
・・・ 1
・i-PMA, α-MeSt resin (manufactured by Sekisui Plastics Co., Ltd., B-12) ・・9 Weight average molecular weight 1306 ・Solvent (manufactured by Kanto Kagaku Co., Ltd., butyl carbitol acetate) ・・7.6 ・Dispersion agent (polyoxyethylene alkyl (or alkyl)
- Phosphate ester of 0.4 kylaryl) Using the above gold ink and using the same intaglio as in Example 1, by the same gravure offset method as in Example 1, the widths of 85, 60, 42 were printed on the alumina substrate. ,34,18μ
A pattern with a height of 4 μm and a height of 4 μm was printed. The obtained pattern was of high quality with good linearity and no scratches or chips. Further, a thick gold film pattern was obtained under the same non-oxidizing atmosphere and firing conditions as in Example 2. It was able to withstand a peel test and had a sheet resistance value of 11 to 21 mΩ/□.

Example 4 A fine gold pattern was printed on an alumina substrate using the same intaglio plate as in Example 1, the same gold ink as in Example 3, and the same gravure offset method as in Example 1. The printed pattern had good linearity and film thickness accuracy. Subsequently, the gold thick film pattern printed on the substrate was dried at 120° C. for 10 minutes to evaporate and remove the solvent contained in the thick film composition. Further, firing was performed in air in an electric furnace in which the temperature of the high temperature holding part was maintained at 850°C. The firing conditions were programmed so that the time required at the highest temperature part was 10 minutes and the total firing time was 60 minutes. As a result, the organic polymer contained in the film to make it suitable for printing decomposed as the temperature rose, making it possible to obtain a thick gold film pattern with excellent edge straightness and less occurrence of scratches and chips. It can also withstand a peel test, with a 13~
The sheet resistance value was 22 mΩ/□.

Example 5 Using three ceramic rolls,
A silver ink was prepared by passing through a mill base having the composition shown below six times.

・Silver (average particle size 2.0 μm)
・・79 (parts by weight) ・Glass frit (manufactured by Nippon Electric Glass Co., Ltd.,
GA-9) ... 3 - Zinc oxide (manufactured by Kanto Kagaku Co., Ltd.)
・・・ 1
・i-BMA, α-MeSt, MMA resin (manufactured by Sekisui Plastics Co., Ltd., ・・10
IBM7L-3) Weight average molecular weight 32060
・Solvent (manufactured by Kanto Kagaku Co., Ltd., butyl carbitol acetate) ・・6.6 ・Dispersant (polyoxyethylene alkyl (or alkaline)
...0.4 phosphoric acid ester of kylaryl)) Using the same intaglio as in Example 1, and using the same gravure offset method as in Example 1, a pattern with a width of 85 mm was printed on an alumina substrate.
Silver fine patterns with dimensions of 60, 42, 34, and 18 μm and a height of 3 μm were printed. The printed pattern has linearity,
Both film thickness accuracy was good. 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 the film to make it suitable for printing decomposed as the temperature rose, making it possible to obtain a thick silver film pattern with excellent edge straightness and less occurrence of scratches and chips. It was also able to withstand a peel test and had a sheet resistance value of 7.5 to 14.5 mΩ/□.

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

[0037] As a result, the organic polymer contained in order to provide printing suitability decomposes as the temperature rises, making it possible to obtain a silver thick film pattern with excellent edge linearity and less occurrence of scratches and chips. done. It was also able to withstand a peel test, and had a sheet resistance value of 10 to 16 mΩ/□, which was comparable to that obtained when fired in a non-oxidizing atmosphere.

Example 7 Using three ceramic rolls, a mill base having the composition shown below was passed through six times for kneading to prepare a copper ink.

・Copper (average particle size 0.05 μm)
...79 (parts by weight)
・Glass frit (manufactured by Nippon Electric Glass Co., Ltd., G
A-9) ... 3 - Zinc oxide (manufactured by Kanto Kagaku Co., Ltd.)
・・ １・
i-BMA, α-MeSt resin (manufactured by Sekisui Plastics Co., Ltd., IBS-6)... 8 Weight average molecular weight 4750 ・Solvent (manufactured by Kanto Kagaku Co., Ltd., butyl carbitol acetate) ・・8.6 ・Dispersant (Polyoxyethylene alkyl (or alkyl)
- Phosphate ester of 0.4 kylaryl) Using the same intaglio as in Example 1, a copper fine pattern was printed on an alumina substrate by the same gravure offset method as in Example 1. Subsequently, firing was performed under the same conditions as in Example 2. As a result, it was possible to obtain a copper thick film pattern with excellent edge linearity and less occurrence of scratches and chips. It can also withstand peeling tests and has a 6.
The sheet resistance value was ~13 mΩ/□. By using a powder with a small average particle size, the sheet resistance value is reduced. In Example 7, an example was given of copper powder, but there is no problem with gold, silver powder, or a mixture.

In Examples 1 and 7, a copolymer of polyiso-butyl methacrylate (i-BMA) and poly-α-methylstyrene (α-MeSt) was used as the resin; Polyiso-butyl methacrylate (i-BMA), poly-α-methylstyrene (α-MeSt), and polymethyl methacrylate (M
In Examples 3 and 4, a copolymer of MA) was used.
Although a copolymer product of so-propyl methacrylate (i-PMA) and poly-α-methylstyrene (α-MeSt) was used, each may be used alone or a copolymer product may be mixed.

Furthermore, polyiso-propyl methacrylate (i-PMA), polytetrafluoroethylene, polyiso-propyl methacrylate (i-PMA), poly-α-methylstyrene (α-MeSt), and polymethyl methacrylate (MMA) It is also possible to use copolymer products. Of course, this is done in consideration of the mutual compatibility of the resins and the amount of solubility in the solvent. However, common acrylic resins (for example, poly n-butyl methacrylate) have poor scattering properties and cannot be used. Furthermore, in order to improve pigment dispersion, it is also possible to use a copolymer of glycidyl methacrylate or the like in an amount of 5% or less. However, it is necessary that the resin contains at least 5 to 20% by weight of α-methylstyrene, and in areas exceeding this range, or when using only acrylic resin, resin scattering properties are poor, and the formed conductive thick film The sheet resistance value of the pattern was high. Moreover, when using polymethyl methacrylate as an acrylic resin, it is desirable that it is 20-25 weight%. In areas beyond this range, ink printability is poor and
The scattering properties of the resin also deteriorate. In addition, if the average molecular weight of the resin is 100,000 or more, the ink viscosity becomes high and becomes unsuitable for printing, and if it is less than 1,300, the scattering property during firing will deteriorate. That is, the average molecular weight of the resin is preferably 100,000 to 1,300, and the most preferable average molecular weight is 40,000 to 1,300 as shown in FIG. 3. When the content of the resin is 15% by weight or more based on the total 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 unsuitable for printing. In other words, the content of the resin is 2% of the total ink.
~15% by weight is preferred, most preferred (Figure 2)
As shown in , the content was 2 to 10% by weight based on the entire ink.

Examples 1, 2, 7 as conductive metal powder
Copper was used in Examples 3 and 4, gold was used in Examples 5 and 6, but the invention was not limited to these; copper powder was used in Examples 3 and 5, and gold powder was used in Examples 1 and 5. 2, 5, 6, 7, silver powder may be used in Examples 1, 2, 3, 4, 7,
It is also possible to mix and use conductive metal powder.

The content of these conductive metal powders is preferably 78 to 86% by weight based on the total weight of the ink. If it is smaller than this range, the thick film after firing will not be dense. If it is larger than this range, the viscosity of the ink becomes too high and is unsuitable for printing. Further, the average particle size of the conductive metal powder is preferably 0.05 to 3.0 μm. 0.0
When the average particle size is smaller than 5 μm, the surface area of the entire particle becomes large, requiring an increase in the amount of vehicle in the ink, and the content of the conductive metal decreases. 3.0μ
If it is larger than m, there is a problem that the sheet resistance value becomes large because the firing is not performed precisely.

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

In addition, Examples 1 and 2 as transition metal oxides
, 3, 4, 5, 6, and 7 used zinc oxide,
The materials are not limited to these, and titanium oxide, chromic oxide, cadmium oxide, and nickel monoxide may be used alone or in combination, depending on printing conditions and drying conditions. When the content of the transition metal oxide was less than 0.5% by weight based on the total amount of the ink, the adhesive strength of the fired thick film to the substrate was so low that it 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 was sufficient to withstand a peel test.

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

Further, if the dispersant amount is less than 0.05% by weight based on the total amount of the ink, the ink will lack storage stability due to poor dispersibility, and if it is more than 5.0% by weight, the thick film pattern after baking will be poor. The amount remaining inside increased, and the sheet resistance value increased. That is, it is desirable that the content of the dispersant is 0.05 to 5.0% by weight based on the entire ink.

In addition, when firing in a non-oxidizing atmosphere, when the oxygen concentration is 10 ppm or more, the influence of oxygen is large in the process of scattering organic substances, and the residual carbon and residual oxygen concentrations in the conductive thick film become oxidizing. The results were at the same level as firing in an atmosphere. Therefore, when the oxygen concentration is 10 ppm or more,
The sheet resistance value is the same as that of firing in an oxidizing atmosphere,
Compared to the sheet resistance value when the oxygen concentration was 10 ppm or less, the sheet resistance value was increased by about 2 mΩ/□. That is, when firing in a non-oxidizing atmosphere, it is desirable that the oxygen concentration be 10 ppm or less. Furthermore, since the copper ink is usually fired in a non-oxidizing atmosphere, the silver ink 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 by forming a printed pattern using offset printing, and by firing in a non-oxidizing atmosphere or an oxidizing atmosphere to scatter organic substances. It has better edge straightness than conventional screen printing methods, and it is possible to form fine patterns with fewer scratches and chips. The present invention is effective in that it enables the preparation of a conductive ink suitable for the above-mentioned printing method, which is composed of a vehicle containing an organic binder and an organic binder.

[Brief explanation of the drawing]

FIG. 1 (a) is a cross-sectional view of a method of filling ink into an intaglio plate. (b) A cross-sectional view of a method of transferring a pattern from an intaglio to a blanket. (c) A cross-sectional view of a method of pressure-bonding and transferring a pattern on a blanket to a substrate.

FIG. 2 is a graph showing the weight percentage of the organic binder relative to the total ink amount and the curve of the amount of copper ink transferred to the object in Example 1 and Example 2;

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

[Explanation of symbols]

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

Claims (24)

[Claims] 1. Conductive metal powder, glass frit, transition metal oxide, and dispersant; and polyiso-butyl methacrylate, polyiso-propyl methacrylate, polymethyl methacrylate, polytetrafluoroethylene, or poly-α-methyl. A conductive ink comprising a vehicle containing an organic binder comprising at least one type of styrene. 2. The conductive ink according to claim 1, wherein the organic binder is composed of a copolymer of poly-α-methylstyrene and polyiso-butyl methacrylate. 3. The organic binder is composed of a copolymer having a ratio of 5 to 20% by weight of poly-α-methylstyrene and 80 to 95% by weight of polyisobutyl methacrylate. Conductive ink as described. 4. The conductive ink according to claim 1, wherein the organic binder is composed of a copolymer of poly-α-methylstyrene, polyiso-butyl methacrylate, and polymethyl methacrylate. 5. The organic binder is 5 to 20% by weight of poly-α-methylstyrene, 60 to 90% by weight of polyiso-butyl methacrylate, and 20 to 20% by weight of polymethyl methacrylate.
Claim 1 consisting of a copolymer having a ratio of 25% by weight.
or 4. The conductive ink according to any one of 4. 6. The conductive ink according to claim 1, wherein the organic binder is composed of a copolymer of poly-α-methylstyrene and polyiso-propyl methacrylate. 7. The conductive material according to claim 1, wherein the organic binder is composed of a copolymer having a ratio of 5 to 20% by weight of poly-α-methylstyrene and 80 to 95% by weight of polyiso-propyl methacrylate. Sex ink. 8. Claim 1, wherein the organic binder is composed of a copolymer of poly-α-methylstyrene, polyiso-propyl methacrylate, and polymethyl methacrylate.
Conductive ink as described. 9. The organic binder is 5 to 20% by weight of poly-α-methylstyrene, 60 to 90% by weight of polyiso-propyl methacrylate, and 20% by weight of polymethyl methacrylate.
9. A conductive ink according to claim 1 or 8, comprising a copolymer having a ratio of ˜25% by weight. Claim 10: The weight average molecular weight of the organic binder is 1.
2. The conductive ink according to claim 1, wherein the conductive ink has a molecular weight of 0,000 to 1,300. Claim 11: The amount of organic solvent constituting the vehicle is 3
-13% by weight, glass frit amount 3-4% by weight, transition metal oxide 0.5-2.0% by weight, dispersant 0.05%
5. The conductive ink of claim 1, wherein the conductive metal powder comprises 78-86% by weight. 12. The conductive ink according to claim 1, wherein the content of the organic binder is 2 to 15% by weight based on the total ink. 13. The conductive ink according to claim 1, wherein the amount of the organic solvent constituting the vehicle is in a weight ratio of 0.04 to 0.18 with respect to the total amount of powder. 14. The conductive ink according to claim 1, wherein the conductive metal powder is composed of at least one of copper, gold, and silver. [Claim 15] The average particle size of the conductive metal powder is 0.0.
The conductive ink according to claim 1, which has a diameter of 5 to 3.0 μm. 16. The organic solvent constituting the vehicle is α-
Claim 1 consisting of at least one of terpineol, butyl carbitol, butyl carbitol acetate, 2,2,4-trimethyl 1-3-hydroxypentyl isobutyrate, 2-butoxyethanol, and 2-ethoxyethanol. Conductive ink as described. 17. The conductive ink according to claim 1, wherein the transition metal oxide is composed of at least one of zinc oxide, titanium oxide, dichromic oxide, cadmium oxide, and nickel monoxide. 18. A step of filling conductive ink into the recesses of the intaglio plate, a step of transferring the conductive ink in the recesses of the intaglio plate onto a blanket whose surface is coated with an elastic body mainly composed of silicone resin, A conductive thick film characterized by comprising the steps of transfer printing the transferred conductive thick film pattern onto a substrate, firing the conductive pattern to scatter organic matter, and sintering the conductive pattern. Method of forming a film pattern. 19. The method for forming a conductive thick film pattern according to claim 18, wherein the conductive ink is the conductive ink according to claim 1. 20. Claim 1, characterized in that the elastic body mainly composed of silicone resin has a hardness of 30 to 60 degrees.
Method for forming a conductive thick film pattern according to 8. 21. Transfer pressure in the step of transferring the ink in the concave portions of the intaglio plate onto the blanket whose surface is coated with an elastic material mainly composed of silicone resin, and transfer the conductive thick film pattern transferred onto the blanket to the substrate. 19. The method of forming a conductive thick film pattern according to claim 18, wherein the printing pressure in the step of transfer printing on the pattern is 2 to 6 kg/cm2. 22. The method for forming a conductive thick film pattern according to claim 18, wherein the oxygen concentration in the non-oxidizing atmosphere baking step is 10 ppm or less. 23. The method for forming a conductive thick film pattern according to claim 18, wherein the temperature of the high temperature holding part in the non-oxidizing atmosphere firing step is 850 to 975°C. 24. The method for forming a conductive thick film pattern according to claim 18, wherein the temperature of the high temperature holding part in the oxidizing atmosphere baking step is 800 to 925°C.