JP5876758B2 - Ink composition and pattern forming method - Google Patents

Description

  The present invention relates to an ink composition used for a film formed on a metal substrate.

  Conventionally, a mask agent is used when a metal substrate is partially etched. A strong acid such as hydrochloric acid is used as an etchant for etching the metal substrate. For this reason, as a characteristic requested | required of a mask agent, the acid resistance with respect to the etching liquid at the time of an etching and favorable board | substrate adhesiveness are calculated | required. Until now, what combined the adhesive agent component with the novolak resin as a mask agent mentioned above is known (patent documents 1 and 2).

JP 2004-347617 A Japanese Patent Laid-Open No. 6-027657

  Currently, the application of a printing resist is being studied for the purpose of reducing the number of processes. Accordingly, there is a need for an ink composition that provides the above acid resistance and adhesion of a substrate (particularly a metal substrate) in addition to the ability to form a pattern by a printing method. An ink composition using an adhesive component or the like in a conventional photosensitive composition has insufficient adhesion to a metal substrate. For this reason, when the pattern formed on the metal substrate using the said ink composition was immersed in strong acids, such as hydrochloric acid, the subject that a pattern peeled from the metal substrate occurred.

  The present invention has been made in view of these problems, and an object thereof is to improve the adhesion of a film to a metal substrate when the film is formed on the metal substrate using an ink composition containing a novolac resin. It is in providing technology that can.

  One embodiment of the present invention is an ink composition. The ink composition has a novolak resin (A) having an area with a weight average molecular weight of 3000 or less, 40% or more, a carboxybenzotriazole-based compound (B), barium sulfate (GPC) chart and a barium sulfate (GPC) chart. C).

  When a film is formed on a metal substrate using the ink composition of this aspect, the adhesion of the film to the metal substrate can be improved.

  In the ink composition of the above aspect, the ratio Cw between the content Cw (% by mass) of the barium sulfate (C) in the entire composition and the content Aw (% by mass) of the novolak resin (A) in the entire composition. / Aw may be 1 or more. The ink composition may be non-photosensitive.

  Another embodiment of the present invention is a pattern forming method. The pattern forming method includes a step of forming a mask pattern by a printing method using any one of the ink compositions described above on a substrate, a step of baking the mask pattern, etching the substrate, And a step of removing the mask pattern. In the pattern forming method according to this aspect, the substrate may be a metal substrate.

  According to the present invention, when a film is formed on a metal substrate using an ink composition containing a novolac resin, the adhesion of the film to the metal substrate can be improved.

1A to 1C are schematic cross-sectional views showing a pattern forming process on a metal substrate. FIGS. 2A and 2B are GPC charts of novolak resin (A1: unpurified product) and novolak resin (A1: purified product), respectively. 3A and 3B are GPC charts of novolak resin (A2: unpurified product) and novolak resin (A3: unpurified product), respectively.

  The ink composition according to the embodiment includes a novolac resin (A), a carboxybenzotriazole-based compound (B), and barium sulfate (C). The ink composition is preferably non-photosensitive.

  The novolak resin (A) has an average molecular weight of 3000 or less in an area of 40% or more in a gel permeation chromatography (GPC) chart. The higher this ratio, the better the adhesion when immersed in an acidic aqueous solution. The content of the novolak resin (A) with respect to the entire ink composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass.

  The novolak resin (A) is a novolak resin obtained by reacting the phenols exemplified below with the aldehydes exemplified below under an acidic catalyst such as hydrochloric acid, sulfuric acid, formic acid, oxalic acid, paratoluenesulfonic acid, etc. Etc.

  Examples of phenols include phenol; cresols such as m-cresol, p-cresol, and o-cresol; xylenols such as 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, and 3,4-xylenol. M-ethylphenol, p-ethylphenol, o-ethylphenol, 2,3,5-trimethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol, 3-tert-butylphenol, 2-tert Alkylphenols such as butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol; p-methoxyphenol, m-methoxyphenol, p-ethoxyphenol, m-ethoxyphenol, p -Propoxyphe And alkoxyphenols such as m-propoxyphenol; isopropenylphenols such as o-isopropenylphenol, p-isopropenylphenol, 2-methyl-4-isopropenylphenol, 2-ethyl-4-isopropenylphenol Arylphenols such as phenylphenol; polyhydroxyphenols such as 4,4′-dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone, pyrogallol, and the like. These may be used alone or in combination of two or more. Among these phenols, m-cresol and p-cresol are particularly preferable.

  Examples of aldehydes include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, butyraldehyde, trimethylacetaldehyde, acrolein, crotonaldehyde, cyclohexanealdehyde, furfural, furylacrolein, benzaldehyde, terephthalaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde. , Β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chloro Benzaldehyde, Cinnamon Alde Hydride and the like. These may be used alone or in combination of two or more. Among these aldehydes, formaldehyde is preferable because of its availability.

  The novolac resin (A) may be composed of one kind of novolac resin or may be composed of two or more kinds of novolac resins. When the novolak resin (A) is composed of two or more types of novolak resins, the Mw of each novolak resin is not particularly limited, but the novolak resin (A) as a whole is prepared so that the Mw is 1000 to 20000. preferable.

  A characteristic common to the novolak resin (A) described above is excellent acid resistance.

［式（Ｂ）中、Ｒは、水素原子または炭素数１〜２０のアルキル基である。］ The carboxybenzotriazole-based compound (B) is represented by the following formula (B). The content of the carboxybenzotriazole-based compound (B) with respect to the entire ink composition is preferably 0.01 to 10% by mass, and more preferably 0.1 to 1% by mass.

[In Formula (B), R is a hydrogen atom or a C1-C20 alkyl group. ]

  The content of barium sulfate (C) with respect to the entire ink composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass. Moreover, ratio Cw / Aw of content Cw (mass%) of barium sulfate (C) in the whole composition and content Aw (mass%) of novolak resin (A) in the whole composition is 1 or more. Is preferable, and is more preferably larger than 1.

  The ink composition according to the embodiment is prepared by dissolving or dispersing the novolak resin (A), the carboxybenzotriazole compound (B), and barium sulfate (C) in the solvent (S).

  Examples of the solvent (S) include a solvent (S1) having a boiling point of 180 ° C. or higher and a solvent (S2) having a boiling point of less than 180 ° C. Specific examples of (S1) include ethylene glycol, hexylene glycol, propylene glycol diacetate, 1,3-butylene glycol diacetate, diethylene glycol, dipropylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, Diethylene glycol monobutyl ether, diethylene glycol monophenyl ether, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether acetate, diethylene glycol monomethyl ether acetate, di Tylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monophenyl ether acetate, dipropylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, glycerin, benzyl alcohol, 3-methyl-3-methoxybutyl acetate, 3-ethyl- 3-methoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentyl acetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate, 3-methyl-3-methoxypentyl acetate, 3-methyl-4- Methoxypentyl acetate, 4-methyl-4-methoxypentyl acetate, dihexyl ether, acetic acid Njiru, ethyl benzoate, diethyl maleate, .gamma.-butyrolactone, etc. terpineol and the like. These may be used alone or in combination of two or more.

  Examples of the solvent (S2) include ketones such as cyclohexanone, methyl-n-pentyl ketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols such as ethylene glycol and propylene glycol; propylene glycol monomethyl ether acetate (PGMEA), Derivatives of polyhydric alcohols such as propylene glycol monomethyl ether (PGME), dipropylene glycol dimethyl ether and propylene glycol propyl ether; and esters such as ethyl acetoacetate, butyl lactate and diethyl oxalate. Among (S2), propylene glycol monomethyl ether acetate is preferable.

  70 mass% or more is preferable, as for content of (S1) with respect to a solvent (S), 90 mass% or more is more preferable, and 100 mass% may be sufficient. 0-30 mass% is preferable and, as for content of (S2) with respect to a solvent (S), 0-10 mass% is more preferable. In the ink composition according to the embodiment, the content of the solvent (S) is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass.

  When a film is formed on a metal substrate using the ink composition described above, the adhesion of the film to the metal substrate can be improved. Moreover, by making the ratio Cw / Aw greater than 1, the adhesion of the film to the metal substrate can be further improved.

(Pattern formation method)
As shown in FIG. 1A, a screen printing method, an ink jet printing method, a roll coat printing method, a relief printing method, an intaglio printing method using the above-described ink composition on a metal substrate 10 such as copper, nickel, or aluminum. The mask pattern 20 is formed using a printing method such as a printing method or an offset printing method. Subsequently, the mask pattern 20 is heated to bake the mask pattern 20. The heating conditions are appropriately set depending on the components of the ink composition, the film thickness of the mask pattern 20, and the like, and are, for example, 200 ° C. and 3 minutes.

  Subsequently, as shown in FIG. 1B, the metal substrate 10 exposed at the opening of the mask pattern 20 is selectively removed using an etching solution such as hydrochloric acid, so that the opening (exposed portion) of the mask pattern 20 is obtained. The metal substrate 10 is etched to transfer the mask pattern.

  Subsequently, as shown in FIG. 1C, the mask pattern 20 is removed after the etching process. Examples of the removing method include a method of immersing in an aqueous alkali solution, an organic solvent, a commercially available stripping solution, etc. for about 5 to 10 minutes at room temperature for peeling. Examples of the alkaline aqueous solution include a sodium hydroxide aqueous solution and a tetramethylammonium hydroxide (TMAH) aqueous solution. Examples of the organic solvent include propylene glycol monomethyl ether acetate (PGMEA) and dimethyl sulfoxide (DMSO). As a commercially available stripping solution, an organic solvent-based peeler 105 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) or the like can be used. As a result, a pattern in which convex portions corresponding to the mask pattern 20 are transferred onto the metal substrate 10 can be obtained. In addition, as a function of the convex part formed in the metal substrate 10, an electrode is mentioned, for example.

  Through the above steps, a convex portion having a predetermined pattern can be formed on the metal substrate. Since the ink composition described above is excellent in substrate adhesion, acid resistance, and pattern formation accuracy, a desired pattern can be formed on the solar cell substrate with high accuracy. In addition, since a pattern is formed on a metal substrate by a printing method without passing through complicated steps such as photolithography, the manufacturing process of electrodes and the like is simplified, and thus the manufacturing cost of a solar cell including the electrodes is reduced. Can be reduced.

  Further, since the ink composition is non-photosensitive, a desired pattern can be formed using a printing technique such as screen printing without using a photolithography method. Thereby, the process of pattern formation can be simplified.

  Examples of the present invention will be described below. However, these examples are merely examples for suitably explaining the present invention, and do not limit the present invention.

樹脂成分としてのノボラック樹脂は、いずれも下記式で表される。

ただし、ノボラック樹脂（Ａ１：未精製品）は、重量平均分子量（Ｍｗ）が１３０００、重量平均分子量（Ｍｗ）／数平均分子量（Ｍｎ）が１８．２である。ノボラック樹脂（Ａ２：未精製品）は、Ｍｗが１１５００、Ｍｗ／Ｍｎが１４．２である。ノボラック樹脂（Ａ３：未精製品）は、Ｍｗが３７００、Ｍｗ／Ｍｎが４．６３である。ノボラック樹脂（Ａ１：精製品）は、Ｍｗが２２０００、Ｍｗ／Ｍｎが１４．０である。 Table 1 shows the types of components of the ink compositions used in Examples 1-3 and Comparative Examples 1-8 and the content of each component. The inks of Examples and Comparative Examples were prepared by dissolving the components shown in Table 1 in a solvent (tripropylene glycol monomethyl ether (MFTG, boiling point 220 ° C.)). The content of the solvent corresponds to the remaining amount excluding the resin, additives and fillers shown in Table 1. In Examples 1 to 3 and Comparative Examples 2, 4, 6, and 8, the content of the additive (B1) was performed in two ways.

Any novolak resin as a resin component is represented by the following formula.

However, the novolak resin (A1: unpurified product) has a weight average molecular weight (Mw) of 13,000 and a weight average molecular weight (Mw) / number average molecular weight (Mn) of 18.2. The novolak resin (A2: unpurified product) has an Mw of 11500 and an Mw / Mn of 14.2. The novolak resin (A3: unpurified product) has Mw of 3700 and Mw / Mn of 4.63. The novolak resin (A1: purified product) has Mw of 22000 and Mw / Mn of 14.0.

About each novolak resin, the gel permeation chromatography (GPC) chart was acquired using the liquid chromatography (model number Shodex GPC SYSTEM 11 (made by Showa Denko KK)). FIGS. 2A and 2B are GPC charts of novolak resin (A1: unpurified product) and novolak resin (A1: purified product), respectively. 3A and 3B are GPC charts of novolak resin (A2: unpurified product) and novolak resin (A3: unpurified product), respectively. From the obtained GPC chart, the area ratio of a weight average molecular weight of 3000 or less was calculated for each novolak resin. The obtained results are shown in Table 2.

添加剤（Ｂ’１）は、下記式（Ｂ’１）で表される。

添加剤（Ｂ’２）は、下記式（Ｂ’２）で表されるベンゾトリアゾールである。

Returning to the description of the components in Table 1, the additive (B1) is carboxybenzotriazole represented by the following formula (B1).

The additive (B′1) is represented by the following formula (B′1).

The additive (B′2) is benzotriazole represented by the following formula (B′2).

(Adhesion evaluation)
Each of the produced inks was printed on a Cu substrate by a screen printing method to form patterns having a thickness of 10 μm, 500 μm and a thickness of 10 μm, 1000 μm. The formed pattern was dried on a hot plate at 200 ° C. for 3 minutes.

  The formed pattern (film) was immersed in a 35% aqueous hydrochloric acid solution, and the presence or absence of pattern peeling was observed. The evaluation results are shown in Table 1, where A is the case where no pattern peeling is observed, and C is the case where the pattern is completely peeled. In the pattern formed using the ink of Example 1-3, peeling of the pattern was not confirmed even after immersion in a 35% aqueous hydrochloric acid solution for 5 minutes, and no significant change in the surface state occurred. On the other hand, in the pattern formed using the ink of Comparative Example 1-8, it was confirmed that the pattern completely peeled after being immersed in a 35% hydrochloric acid aqueous solution for 5 minutes. In Examples 1 to 3 and Comparative Examples 2, 4, 6, and 8, there was no particular difference due to the difference in the content of the additive (B1).

  Based on the above results, it was confirmed that the pattern formed using the ink of Example 1-3 had sufficient resistance to acid and sufficient adhesion to the metal substrate (Cu substrate). It was done.

実施例２、４−７の各インク組成物を用いて上述した密着性評価を３５％塩酸水溶液の浸漬時間を５分延長してそれぞれ実施した。３５％塩酸水溶液に１０分間浸漬した後もパターンの剥離が認められなかった場合をＡ、１０分間浸漬後、パターンの一部が剥離された場合をＡ’、１０分間浸漬後、パターンが完全に剥離された場合をＢとした。その結果、実施例４−７では、浸漬時間を長くした場合にパターンの剥離が生じることが確認された。すなわち、組成物全体における硫酸バリウム（Ｃ）の含有量Ｃｗ（質量％）と、組成物全体におけるノボラック樹脂（Ａ）の含有量Ａｗ（質量％）との比Ｃｗ／Ａｗが１以上であることが好ましく、１より大きいことがより好ましいことが確認された。 (Evaluation of filler content dependency on adhesion)
Table 3 shows the type of each component and the content of each component of the ink composition of Example 4-7 in which the filler content of the ink composition of Example 2 was changed.

Using the ink compositions of Examples 2 and 4-7, the above-described adhesion evaluation was performed by extending the immersion time of a 35% hydrochloric acid aqueous solution for 5 minutes. When the pattern was not peeled after being immersed in a 35% hydrochloric acid aqueous solution for 10 minutes, the pattern A was completely removed after A was immersed for 10 minutes and after A was immersed for 10 minutes. The case where it peeled was set to B. As a result, in Example 4-7, it was confirmed that pattern peeling occurred when the immersion time was increased. That is, the ratio Cw / Aw of the content Cw (mass%) of barium sulfate (C) in the whole composition and the content Aw (mass%) of the novolak resin (A) in the whole composition is 1 or more. It was confirmed that it is more preferable that it is greater than 1.

10 metal substrate, 20 mask pattern

Claims (4)

In a gel permeation chromatography (GPC) chart, a novolak resin (A) having an area having a weight average molecular weight of 3000 or less relative to the entire area of the GPC chart is 40% or more;
A carboxybenzotriazole compound (B);
Barium sulfate (C),
A solvent (S);
And an ink composition which is non-photosensitive .   The ratio Cw / Aw of the content Cw (mass%) of the barium sulfate (C) in the whole composition and the content Aw (mass%) of the novolak resin (A) in the whole composition is 1 or more. Item 2. The ink composition according to Item 1. Forming a mask pattern on a substrate by a printing method using the ink composition according to claim 1 or 2 ,
A step of baking the mask pattern;
Etching the substrate and transferring the mask pattern;
Removing the mask pattern;
A pattern forming method including: The pattern formation method according to claim 3 , wherein the substrate is a metal substrate.

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