JPWO2012133415A1 - Resin paste, solar cell and manufacturing method thereof, resin film and semiconductor device - Google Patents

Abstract

A mixed solvent comprising a first polar solvent (A1) and a second polar solvent (A2) having a boiling point lower than that of the first polar solvent (A1) in a mass ratio of 6: 4 to 9: 1; And a heat-resistant resin (B) that is soluble in the mixed solvent at room temperature, soluble in the first polar solvent (A1) at room temperature, and insoluble in the second polar solvent (A2). And a heat-resistant resin (C) that is insoluble in the mixed solvent, and the resin in which the heat-resistant resin (C) is dispersed in a solution containing the mixed solvent and the heat-resistant resin (B) paste.

Description

  The present invention relates to a resin paste, a method for manufacturing a solar cell using the resin paste, a solar cell manufactured by the method, a resin film, and a semiconductor device including the resin film.

  Resins such as polyimide resins having excellent heat resistance and mechanical properties are used in the field of electronics as surface protective films, interlayer insulating films, or stress relaxation materials for semiconductor elements. In recent years, screen printing methods that do not require complicated processes such as exposure, development, or etching have attracted attention as image forming methods for resin films used in these applications.

  For the screen printing method, for example, a resin paste having a thixotropic property including a base resin, a filler, and a solvent as constituent components is used. In the resin paste, silica fine particles or polyimide fine particles are often used as fillers for imparting thixotropic properties.

  However, when the resin paste containing these fillers is heated and dried, many voids and bubbles remain at the filler interface. For this reason, the film strength and electrical insulation of the resin film formed from the resin paste are not sufficient.

  In view of such a problem, for example, in Patent Document 1, a resin pattern is formed using a resin paste in which an organic filler (soluble filler) compatible with a base resin and a solvent during heating is mixed with the base resin and the solvent. It is disclosed. Patent Document 2 also discloses a technique of adding a low elastic filler, liquid rubber, or the like in order to impart characteristics such as low elasticity to the resin paste.

JP-A-2-289646 International Publication No. 01/66645

  However, the resin film obtained by using a conventional resin paste has irregularities on the surface of the resin film due to agglomerates of insoluble fillers such as low-elasticity fillers, organic fillers that remain enlarged due to enlargement, and other foreign matters. May remain and the flatness of the surface may deteriorate. The unevenness on the surface of the resin film may cause abnormal plating or disconnection in the wiring when the wiring is formed after the resin film is formed.

  Accordingly, the present invention provides a resin paste that can be used for screen printing, has a precise resolution, and can form a resin film having excellent surface flatness, a method for manufacturing a solar cell using the resin paste, and a method for manufacturing the resin cell An object of the present invention is to provide a solar cell, a resin film, and a semiconductor device including the resin film.

  That is, in the present invention, the mass ratio of the first polar solvent (A1) and the second polar solvent (A2) having a boiling point lower than that of the first polar solvent (A1) is 6: 4 to 9: 1. And a heat-resistant resin (B) soluble in the mixed solvent at room temperature, and soluble in the first polar solvent (A1) and insoluble in the second polar solvent (A2) at room temperature. And a heat resistant resin (C) that is insoluble in a mixed solvent, and a resin paste in which the heat resistant resin (C) is dispersed in a solution containing the mixed solvent and the heat resistant resin (B) provide.

  Since the mass ratio of the first polar solvent (A1) and the second polar solvent (A2) is 6: 4 to 9: 1, the resin paste is less likely to be dripped and the flowability of printing is extremely high. Sex is obtained. Thereby, the resin paste which can be used for screen printing can be obtained. At the same time, according to the resin paste, the solubility of the heat-resistant resin (C) acting as a filler in the resin paste is increased during the formation of the resin film, so that the surface flatness is excellent and precise resolution is achieved. A resin film having the same can be formed.

  Here, since the screen printability of the resin paste can be improved, the resin paste according to the present invention has a boiling point of the first polar solvent (A1) and a boiling point of the second polar solvent (A2). The difference is preferably 10 to 100 ° C.

  Moreover, the heat resistant resin (B) and the heat resistant resin (C) are each independently at least one selected from polyamide resin, polyimide resin, polyamideimide resin, or a precursor of polyimide resin and polyamideimide resin. It is preferable. Thereby, a resin film excellent in heat resistance and mechanical properties can be obtained.

  The heat-resistant resin (C) dispersed in the solution may be in the form of particles having an average particle size of 50 μm or less.

  The present invention also includes a step of screen-printing the resin paste on the electrode side surface of a substrate having a negative electrode and a positive electrode, and a solar cell manufacturing method including a step of heat-drying the screen-printed resin paste at 100 to 450 ° C. A method and a solar cell produced by the method are provided. Since the solar cell manufactured by the method of the present invention is excellent in the surface flatness of the resin film, wiring abnormalities and disconnection are reduced, and the reliability is excellent.

  Furthermore, the present invention provides a surface roughness of 2 μm or less formed by a method comprising a step of screen-printing the resin paste on a substrate and a step of heating the screen-printed resin paste at 100 to 450 ° C. A resin film is provided.

  Furthermore, the present invention provides a semiconductor device comprising the resin film described above. Since the semiconductor device according to the present invention includes the resin film of the present invention, wiring abnormalities and disconnections are reduced, and the reliability is excellent.

  According to the present invention, a resin paste that can be used for screen printing, has a precise resolution, and can form a resin film with excellent surface flatness, a method for manufacturing a solar cell using the resin paste, and the method A manufactured solar cell, a resin film, and a semiconductor device including the resin film can be provided.

(A) is a schematic cross section of the resin paste immediately after screen-printing on a base material, (b) is a schematic cross section of the resin film obtained by heating the resin paste on a base material. It is a top view which shows typically the process of manufacturing the back electrode type solar cell of the MWT structure which concerns on this embodiment. It is an end elevation which shows typically the process of manufacturing the back electrode type solar cell of the MWT structure concerning this embodiment. (A) is a top view which shows typically an example of the back electrode type solar cell of the IBC structure which concerns on this embodiment, (b) is an example of the back electrode type solar cell of the IBC structure which concerns on this embodiment. It is an end elevation showing typically. (A) is a top view which shows typically an example of the back electrode type solar cell of the EWT structure which concerns on this embodiment, (b) is the back electrode type solar cell of the EWT structure which concerns on this embodiment. It is an end elevation showing typically an example. It is a schematic diagram which shows the manufacturing method of the resin film by screen printing.

  Hereinafter, the resin paste of the present embodiment, a method for manufacturing a solar cell using the resin paste, a solar cell manufactured by the method, a resin film, and a semiconductor including the resin film, with reference to the drawings depending on cases The apparatus will be described, but the present invention is not limited to this. The dimensional ratio in the drawing may be different from the actual dimensional ratio.

<Resin paste>
First, components constituting the resin paste according to the present embodiment will be described. The resin paste according to the present embodiment includes a first polar solvent (A1) and a second polar solvent (A2) having a boiling point lower than the boiling point of the first polar solvent (A1) at a mass ratio of 6: A heat-resistant resin (B) that is soluble in a mixed solvent of 4 to 9: 1, a mixed solvent of the first polar solvent (A1) and the second polar solvent (A2) at room temperature, and room temperature Soluble in the first polar solvent (A1), insoluble in the second polar solvent (A2), and mixing of the first polar solvent (A1) and the second polar solvent (A2) And a heat resistant resin (C) that is insoluble in a solvent. Here, in this specification, "room temperature" is 25 degreeC.

  The heat resistant resin (B) is soluble in a mixed solvent of the first polar solvent (A1) and the second polar solvent (A2) at room temperature, and the heat resistant resin (C) is the first at room temperature. In the resin paste, the heat resistant resin (C) is composed of the first polar solvent (A1) and the second polarity because it is insoluble in the mixed solvent of the polar solvent (A1) and the second polar solvent (A2). It is dispersed in a mixed solvent of the solvent (A2) and the heat resistant resin (B) and acts as a filler. Thereby, in particular, the thixotropy value of the resin paste can be adjusted so that it can be used for screen printing of the resin paste. Furthermore, when the resin paste is heated to a temperature at which the heat resistant resin (C) is dissolved, the heat resistant resin (C) is dissolved and the filler disappears. Thereby, it is possible to give a precise resolution and improve the flatness of the surface of the resin film.

  Examples of the first polar solvent (A1) and the second polar solvent (A2) include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, Polyether alcohol solvents such as tetraethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dipropyl ether, triethylene Glycol dibutyl ether, Ether solvents such as traethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dipropyl ether, tetraethylene glycol dibutyl ether, sulfur-containing solvents such as dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, sulfolane, ethyl acetate, acetic acid Ester solvents such as butyl, cellosolve acetate, ethyl cellosolve acetate, butyrocellosolve acetate, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetophenone, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, 1,3-dimethyl -3,4,5,6-tetrahydro-2 (1H) -pyrimidinone, 1,3-dimethyl-2-imidazolidinone, etc. Lactic acids such as nitrogen-containing solvents, aromatic hydrocarbon solvents such as toluene and xylene, γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-heptalactone, α-acetyl-γ-butyrolactone, ε-caprolactone, etc. Examples include solvents, alcohol solvents such as butanol, octyl alcohol, ethylene glycol, and glycerin, and phenol solvents such as phenol, cresol, and xylenol.

  The combination of the first polar solvent (A1) and the second polar solvent (A2) is appropriately selected from these solvents according to the types of the heat resistant resin (B) and the heat resistant resin (C). Use it.

The first polar solvent (A1) is preferably N-methylpyrrolidone, dimethylacetamide, dimethylformamide, 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H) -pyrimidinone, 1,3- Nitrogen-containing solvents such as dimethyl-2-imidazolidinone, sulfur-containing solvents such as dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfoxide, diethyl sulfoxide, dimethyl sulfone, sulfolane, γ-butyrolactone, γ-valerolactone, γ-caprolactone, Lactone solvents such as γ-heptalactone, α-acetyl-γ-butyrolactone, ε-caprolactone, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetophenone, butanol, octyl alcohol, ethylene glycol, Alcoholic solvents such as serine and the like.
The heat-resistant resin (B) and the heat-resistant resin (C) to be described later are each independently at least one selected from polyamide resin, polyimide resin, polyamideimide resin, or a precursor of polyimide resin and polyamideimide resin. In this case, γ-butyrolactone is particularly preferable as the first polar solvent (A1).

The second polar solvent (A2) is preferably diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dipropyl ether, triethylene glycol diester. Ether solvents such as butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dipropyl ether, tetraethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, Polyether alcohol solvents such as reethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, ethyl cellosolve acetate, butyrocellosolve acetate, etc. Can be mentioned.
The heat-resistant resin (B) and the heat-resistant resin (C) to be described later are each independently at least one selected from polyamide resin, polyimide resin, polyamideimide resin, or a precursor of polyimide resin and polyamideimide resin. In this case, a polyether alcohol solvent or an ester solvent is preferable as the second polar solvent (A2).

  From the viewpoint of improving the screen printability of the resin paste, the resin paste according to this embodiment has a difference between the boiling point of the first polar solvent (A1) and the boiling point of the second polar solvent (A2) of 10 to 10. 100 ° C is preferable, 10 ° C to 50 ° C is more preferable, and 10 ° C to 30 ° C is further preferable. Further, the boiling points of both the first polar solvent (A1) and the second polar solvent (A2) are preferably 100 ° C. or higher from the viewpoint of increasing the pot life of the resin paste during screen printing. More preferably, the temperature is 150 ° C. or higher.

  The heat resistant resin (B) and the heat resistant resin (C) are each independently at least one selected from a polyamide resin, a polyimide resin, a polyamideimide resin, or a precursor of a polyimide resin and a polyamideimide resin. preferable. As a precursor of polyamide resin, polyimide resin, polyamideimide resin, or polyimide resin and polyamideimide resin, for example, aromatic, aliphatic, or alicyclic diamine compound, and polyvalent having 2 to 4 carboxyl groups What is obtained by reaction with carboxylic acid is mentioned. The precursors of polyimide resin and polyamideimide resin mean polyamic acid, which is a substance immediately before dehydration ring closure, which forms a polyimide resin or polyamideimide resin by dehydration ring closure. The heat resistant resin (C) is preferably soluble in the mixed solvent when heated at, for example, 60 ° C. or higher (preferably 60 to 200 ° C., more preferably 100 to 180 ° C.).

  As an aromatic, aliphatic, or alicyclic diamine compound, an arylene group, an alkylene group that may have an unsaturated bond, a cycloalkylene group that may have an unsaturated bond, or these Examples thereof include diamine compounds having a combined group. These groups may be bonded via a carbon atom, an oxygen atom, a sulfur atom, a silicon atom, or a group obtained by combining these atoms. In addition, a hydrogen atom bonded to the carbon skeleton of the alkylene group may be substituted with a fluorine atom. From the viewpoints of heat resistance and mechanical strength, aromatic diamines are preferred.

  Examples of the polyvalent carboxylic acid having 2 to 4 carboxyl groups include dicarboxylic acid or a reactive acid derivative thereof, tricarboxylic acid or a reactive acid derivative thereof, and tetracarboxylic dianhydride. These compounds are dicarboxylic acids, tricarboxylic acids or reactive acid derivatives thereof in which a carboxyl group is bonded to an aryl group or a cycloalkyl group that may have a crosslinked structure or an unsaturated bond in the ring, or It may be an aryl group or a tetracarboxylic dianhydride in which a carboxyl group is bonded to a cycloalkyl group that may have a crosslinked structure or an unsaturated bond in the ring, and the dicarboxylic acid, tricarboxylic acid, or these These reactive acid derivatives and tetracarboxylic dianhydrides are bonded through a single bond or a group of carbon atoms, oxygen atoms, sulfur atoms, silicon atoms, or a combination of these atoms. May be. In addition, a hydrogen atom bonded to the carbon skeleton of the alkylene group may be substituted with a fluorine atom. Of these compounds, tetracarboxylic dianhydride is preferable from the viewpoint of heat resistance and mechanical strength. A combination of an aromatic, aliphatic, or alicyclic diamine compound and a polyvalent carboxylic acid having 2 to 4 carboxyl groups can be appropriately selected depending on the reactivity and the like.

  The reaction can be carried out without using a solvent or in the presence of an organic solvent. The reaction temperature is preferably 25 ° C. to 250 ° C., and the reaction time can be appropriately selected depending on the scale of the batch, the reaction conditions employed, and the like.

  The method of dehydrating and ring-closing the polyimide resin precursor or polyamideimide resin precursor to obtain a polyimide resin or polyamideimide resin is not particularly limited, and a general method can be used. For example, a thermal ring closure method in which dehydration ring closure is performed by heating under normal pressure or reduced pressure, a chemical ring closure method using a dehydrating agent such as acetic anhydride in the presence or absence of a catalyst, and the like can be used.

  The thermal ring closure method is preferably performed while removing water generated by the dehydration reaction from the system. At this time, it is carried out by heating the reaction solution to 80 to 400 ° C, preferably 100 to 250 ° C. At this time, a solvent that azeotropes with water such as benzene, toluene, xylene or the like may be used in combination to remove water azeotropically.

  In the chemical ring closure method, the reaction is preferably carried out at 0 to 120 ° C., preferably 10 to 80 ° C. in the presence of a chemical dehydrating agent. As the chemical dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and benzoic acid, and carbodiimide compounds such as dicyclohexylcarbodiimide are preferably used. At this time, it is preferable to use together a substance that promotes the cyclization reaction, such as pyridine, isoquinoline, trimethylamine, triethylamine, aminopyridine, imidazole. The chemical dehydrating agent is used in an amount of 90 to 600 mol% based on the total amount of the diamine compound, and the substance that promotes the cyclization reaction is used in an amount of 40 to 300 mol% based on the total amount of the diamine compound. Further, a dehydration catalyst such as triphenyl phosphite, tricyclohexyl phosphite, triphenyl phosphate, phosphorus compounds such as phosphoric acid and phosphorus pentoxide, and boron compounds such as boric acid and boric anhydride may be used.

  The reaction solution that has been imidized by the dehydration reaction is compatible with a large excess of the first polar solvent (A1) and the second polar solvent (A2), and has a heat resistant resin ( Pour into lower alcohol such as methanol, water, or a mixture thereof, which is a poor solvent for B) and (C), to obtain a resin precipitate, filter this, and dry the solvent Thus, a polyimide resin or a polyamideimide resin can be obtained. From the viewpoint of reducing the remaining ionic impurities, the thermal ring closure method is preferable.

  Depending on the types of the heat-resistant resin (B) and the heat-resistant resin (C), suitable types of the first polar solvent (A1) and the second polar solvent (A2) can be determined. Examples of suitable combinations (mixed solvents) of the first polar solvent (A1) and the second polar solvent (A2) include the following two types (a) and (b).

(A) the first polar solvent (A1): the nitrogen-containing solvent such as N-methylpyrrolidone and dimethylacetamide; the sulfur-containing solvent such as dimethyl sulfoxide; the lactone solvent such as γ-butyrolactone; the xylenol The phenolic solvent,
Second polar solvent (A2): the ether solvent such as diethylene glycol dimethyl ether; the ketone solvent such as cyclohexanone; the ester solvent such as butyl cellosolve acetate; the alcohol solvent such as butanol; the aromatic carbon such as xylene. Combination with hydrogen solvent.
(B) first polar solvent (A1): the ether solvent such as tetraethylene glycol dimethyl ether; the ketone solvent such as cyclohexanone;
Second polar solvent (A2): ester solvents such as butyl cellosolve acetate and ethyl acetate; alcohol solvents such as butanol; polyether alcohol solvents such as diethylene glycol monoethyl ether; aromatic hydrocarbons such as xylene Combination with system solvents.

Examples of the combination of the heat-resistant resin (B) and the heat-resistant resin (C) applied to the (a) type mixed solvent include the following.
Heat-resistant resin (B): a resin having at least one of structural units represented by the following formulas (1) to (10);
Heat resistant resin (C): A combination with a resin having at least one of the structural units represented by the following formulas (11) to (19).

式（１）中、Ｘは、−ＣＨ_２―、−Ｏ−、−ＣＯ−、−ＳＯ_２−、又は、下記式（ａ）〜（ｉ）で表される基であり、式（ｉ）中、ｐは、１〜１００の整数である。

In the formula (1), X is —CH ₂ —, —O—, —CO—, —SO ₂ —, or a group represented by the following formulas (a) to (i). In the above, p is an integer of 1 to 100.

式（２）中、Ｒ^１及びＲ^２は、それぞれ水素原子又は炭素数１〜６の炭化水素基であり、互いに同じでも異なっていてもよい。Ｘは、式（１）のＸと同じである。

In Formula (2), R ¹ and R ² are each a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and may be the same as or different from each other. X is the same as X in formula (1).

式（３）中、Ｍは、下記式（ｃ）、（ｈ）、（ｉ）又は（ｊ）で表される基であり、式（ｉ）中、ｐは、１〜１００の整数である。

In formula (3), M is a group represented by the following formula (c), (h), (i) or (j), and in formula (i), p is an integer of 1 to 100. .

式（４）中、Ｘは、式（１）のＸと同じである。

In formula (4), X is the same as X in formula (1).

式（５）中、Ｘは、式（１）のＸと同じである。

In formula (5), X is the same as X in formula (1).

式（６）中、Ｒ^３及びＲ^４は、それぞれメチル基、エチル基、プロピル基、又はフェニル基であり、互いに同じでも異なっていてもよく、Ｘは、式（１）のＸと同じである。

In formula (6), R ³ and R ⁴ are each a methyl group, an ethyl group, a propyl group, or a phenyl group, and may be the same or different from each other, and X is the same as X in formula (1). is there.

式（８）中、ｘは、０又は２であり、Ｘは、式（１）のＸと同じである。

In formula (8), x is 0 or 2, and X is the same as X in formula (1).

式（１１）中、Ｙは、下記式（ａ）、（ｃ）又は（ｈ）で表される基である。

In formula (11), Y is a group represented by the following formula (a), (c) or (h).

式（１２）中、Ｙは、式（１１）のＹと同じである。なお、＊の部分は、互いに結合している（以下、同様）。

In formula (12), Y is the same as Y in formula (11). In addition, the part of * has couple | bonded together (hereinafter the same).

式（１４）中、Ｚは、−ＣＨ_２―、−Ｏ−、−ＣＯ−、−ＳＯ_２−、又は、下記式（ａ）若しくは（ｄ）で表される基である。

In formula (14), Z is —CH ₂ —, —O—, —CO—, —SO ₂ —, or a group represented by the following formula (a) or (d).

式（１６）中、Ｚは、式（１４）のＺと同じである。

In formula (16), Z is the same as Z in formula (14).

式（２０）中、Ｘは、式（１）のＸと同じであり、ｎ及びｍはそれぞれ独立に１以上の整数を示す。ｎとｍの比（ｎ／ｍ）は、８０／２０〜３０／７０であることが好ましく、７０／３０〜５０／５０であることがより好ましい。

In formula (20), X is the same as X in formula (1), and n and m each independently represent an integer of 1 or more. The ratio of n to m (n / m) is preferably 80/20 to 30/70, and more preferably 70/30 to 50/50.

  Among the above combinations, a lactone solvent or a nitrogen-containing solvent is used as the first polar solvent (A1), and an ether solvent or an ester solvent is used as the second polar solvent (A2). A resin having a structural unit represented by the formula (1) as (B) and a resin having a structural unit represented by the formula (20) or the formula (16) are used as the heat resistant resin (C). preferable.

Examples of the combination of the heat-resistant resin (B) and the heat-resistant resin (C) applied to the (b) type mixed solvent include the following.
Heat-resistant resin (B): a resin having at least one of structural units represented by the following formulas (21) and (22), or a polysiloxane imide having a structural unit represented by the above formula (6) ,
Heat-resistant resin (C): polyetheramide imide having a structural unit represented by the above formula (1) (where X is a group represented by the following formula (a) or (b)), or Structural units represented by the above formulas (5) to (9) (provided that X in the above formulas (5), (6) and (8) is a group represented by the following formula (a)) In combination with a polyimide having at least one of

式（２２）中、Ｚ^１は、−Ｏ−、−ＣＯ−、又は、下記式（ｄ）、（ｅ）、（ｋ）若しくは（ｌ）で表される基である。Ｒ^５及びＲ^６は、それぞれ下記式（ｍ）又は（ｎ）で表される基であり、互いに同じでも異なっていてもよい。ｒは、１〜１００の整数である。

In Formula (22), Z ¹ is —O—, —CO—, or a group represented by the following Formula (d), (e), (k), or (l). R ⁵ and R ⁶ are groups represented by the following formula (m) or (n), and may be the same or different from each other. r is an integer of 1-100.

  There are no particular restrictions on the order in which the raw materials are charged when preparing the resin paste. For example, the raw materials of the resin paste may be mixed together, or first, the first polar solvent (A1) and the second polar solvent (A2) are mixed, and the heat-resistant resin ( B) is mixed, and then the heat resistant resin (C) is added to the mixed solution of the first polar solvent (A1), the second polar solvent (A2), and the heat resistant resin (B). Good.

  The raw material mixture of the resin paste is a temperature at which the heat resistant resin (C) is sufficiently dissolved in the mixed solution of the first polar solvent (A1), the second polar solvent (A2), and the heat resistant resin (B). It is good to mix well with stirring and the like.

  The resin paste obtained as described above has a heat resistant resin (C) in a solution containing the first polar solvent (A1), the second polar solvent (A2), and the heat resistant resin (B) at room temperature. ) Is dispersed. That is, the heat resistant resin (C) is present as a filler in the resin paste, and the thixotropic property particularly suitable for screen printing can be imparted to the resin paste.

  The heat resistant resin (C) dispersed in the resin paste may be in the form of particles having an average particle size of 50 μm or less, preferably 0.01 to 10 μm, more preferably 0.1 to 5 μm. The maximum particle size is preferably 10 μm, more preferably 5 μm. The average particle size and the maximum particle size of the heat resistant resin (C) can be measured by using a particle size distribution measuring device SALD-2200 manufactured by Shimadzu Corporation.

  The mixing ratio of the first polar solvent (A1) and the second polar solvent (A2) is the kind of the heat resistant resin (B) and the heat resistant resin (C), the first polar solvent (A1) and the second polar solvent (A2). Depending on the solubility or the amount of use in the polar solvent (A2), from the viewpoint of highly balancing the flowability of the resin paste, the resolution of the resin film, the shape retention, and the flatness of the surface, the mixing ratio is 6: 4 to 9: 1, more preferably 6.5: 3.5 to 8.5: 1.5, and particularly preferably 7: 3 to 8: 2.

  In the resin paste according to the present embodiment, the first polar solvent (A1) and the second polar solvent (A2) with respect to 100 parts by mass of the total amount of the heat resistant resin (B) and the heat resistant resin (C). It is preferable to mix | blend 100-3500 mass parts, and it is more preferable to mix | blend 150-1000 mass parts.

  The mixing ratio of the heat-resistant resin (B) and the heat-resistant resin (C) is not particularly limited and may be any compounding amount, but the heat-resistant resin (C) is added to 100 parts by mass of the total amount of the heat-resistant resin (B). On the other hand, it is preferable to mix | blend 10-300 mass parts, and it is more preferable if it is 10-200 mass parts. When the amount of the heat-resistant resin (C) used is 10 parts by mass or more, the thixotropic property of the obtained heat-resistant resin paste tends to be improved, and when it is 300 parts by mass or less, the physical properties of the obtained resin film are improved. Tend to.

  The resin paste according to the present embodiment has a viscosity at 25 ° C. of preferably 30 to 500 Pa · s, more preferably 50 to 400 Pa · s, from the viewpoints of detachability from the printing plate, resolution of the resin film, and shape retention. s, more preferably 70 to 300 Pa · s. When the viscosity at 25 ° C. is 30 Pa · s or more, the resolution of the resin film is further improved, and when it is 500 Pa · s or less, the removability from the screen printing plate is further improved. The viscosity can be controlled by adjusting the non-volatile concentration (hereinafter referred to as NV) of the resin paste, the molecular weight of the first polar solvent (A1), the heat resistant resin (B), or the heat resistant resin (C). For example, the weight average molecular weight of the heat resistant resin (B) and the heat resistant resin (C) measured by gel permeation chromatography in terms of standard polystyrene is 10,000 to 100,000, preferably 20,000 to 80,000, particularly preferably. May be 30000-60000.

  The resin paste according to the present embodiment preferably has a thixotropic coefficient of 2.0 to 10.0, more preferably 2.0 to 6.0, and further preferably 2.5 to 5.5. Most preferably, it is 3.0-5.0. When the thixotropy coefficient is 2.0 or more, the printability is further improved, and when it is 6.0 or less, the workability is further improved.

  The resin paste according to this embodiment satisfies high heat resistance and insulation, and can be used for insulating films such as semiconductor devices and electrochemical devices. Further, for example, by adding a silane coupling agent or the like, it can be used as an adhesive for connecting a semiconductor device or the like.

  In the resin paste according to the present embodiment, a low elastic filler having rubber elasticity may be added depending on the application. Although there is no restriction | limiting in particular in the kind of low elastic filler, The fillers of elastic bodies, such as an acrylic rubber, a fluorine rubber, a silicone rubber, a butadiene rubber, or these liquid rubbers are mentioned. Among these, silicone rubber is preferable in consideration of the heat resistance of the resin composition. The surface of the filler can be chemically modified with a functional group such as an epoxy group, amino group, acrylic group, vinyl group, phenyl group, etc. preferable.

  By adding a low elastic filler to the resin paste, low elasticity can be achieved without impairing heat resistance and adhesion, and the elastic modulus can be controlled. The low elasticity filler having rubber elasticity is preferably finely divided into a spherical shape or an indefinite shape, and has an average particle size of 0.1 to 6 μm, preferably 0.2 to 5 μm, more preferably 0.3 to 4 μm. When the average particle size is 0.1 μm or more, the dispersibility tends to be improved, and when it is 6 μm or less, the flatness of the obtained coating film tends to be improved. The particle size distribution of the low elasticity filler having rubber elasticity is 0.01 to 15 μm, preferably 0.02 to 15 μm, and more preferably 0.03 to 15 μm. When the particle size distribution is 0.01 μm or more, the dispersibility tends to be improved, and when it is 15 μm or less, the flatness of the obtained coating film tends to be improved.

  In the heat resistant resin paste according to this embodiment, the blending amount of the low elasticity filler having rubber elasticity is 5 to 900 mass with respect to 100 mass parts of the total amount of the heat resistant resin (B) and the heat resistant resin (C). Part, preferably 5 to 800 parts by weight.

  In the resin paste according to this embodiment, additives such as a colorant and a coupling agent, and a resin modifier may be further added.

  Examples of the colorant include carbon black, dyes, and pigments.

  Examples of the coupling agent include silane-based, titanium-based, and aluminum-based coupling agents, and the silane-based coupling agent is most preferable.

  The silane coupling agent is not particularly limited, and examples thereof include vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacrylate. Roxypropylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxy Silane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltri Toxisilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-ureidopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane 3-aminopropyl-tris (2-methoxy-ethoxy-ethoxy) silane, N-methyl-3-aminopropyltrimethoxysilane, triaminopropyl-trimethoxysilane, 3-4,5-dihydroimidazol-1-yl -Propyltrimethoxysilane, 3-methacryloxypropyl-trimethoxysilane, 3-mercaptopropyl-methyldimethoxysilane, 3-chloropropyl-methyldimethoxysilane, 3-chloropropyl-dimethoxysilane 3-cyanopropyl-triethoxysilane, hexamethyldisilazane, N, O-bis (trimethylsilyl) acetamide, methyltrimethoxysilane, methyltriethoxysilane, ethyltrichlorosilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, Amyltrichlorosilane, octyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyltri (methacryloyloxyethoxy) silane, methyltri (glycidyloxy) silane, N-β (N-vinylbenzylaminoethyl) -γ-aminopropyl Trimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyl Methoxysilane, γ-chloropropylmethyldiethoxysilane, trimethylsilyl isocyanate, dimethylsilyl isocyanate, methylsilyl triisocyanate, vinylsilyl triisocyanate, phenylsilyl triisocyanate, tetraisocyanate silane, ethoxysilane isocyanate, etc. can be used. These may be used alone or in combination of two or more.

  The titanium-based coupling agent is not particularly limited. For example, isopropyl trioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl isostearoyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, Isopropyltricumylphenyl titanate, isopropyltris (dioctylpyrophosphate) titanate, isopropyltris (n-aminoethyl) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (2, 2-Diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titane , Dicumylphenyloxyacetate titanate, bis (dioctylpyrophosphate) oxyacetate titanate, tetraisopropyl titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetate Nitrate, Titanium Octylene Glycolate, Titanium Lactate Ammonium Salt, Titanium Lactate, Titanium Lactate Ethyl Ester, Titanium Chili Ethanolate, Polyhydroxy Titanium Stearate, Tetramethyl Orthotitanate, Tetraethyl Orthotitanate, Tetarapropyl Orthotitanate, Tetraisobutyl Ortho Titanate, stearyl titanate, cresyl titanate monomer, cresyl Nate polymer, diisopropoxy-bis (2,4-pentadionate) titanium (IV), diisopropyl-bis-triethanolamino titanate, octylene glycol titanate, tetra-n-butoxytitanium polymer, tri-n-butoxytitanium A monostearate polymer, tri-n-butoxytitanium monostearate, etc. can be used, and these 1 type (s) or 2 or more types can also be used together.

  The aluminum coupling agent is not particularly limited. For example, ethyl acetoacetate aluminum diisopropylate, aluminum toys (ethyl acetoacetate), alkyl acetoacetate aluminum diisopropylate, aluminum monoacetyl acetate bis (ethyl acetoacetate), Aluminum tris (acetylacetonate), aluminum = monoisopropoxymonooroxyethyl acetoacetate, aluminum-di-n-butoxide-mono-ethylacetoacetate, aluminum-di-iso-propoxide-mono-ethylacetoacetate, etc. Aluminum chelate compound, aluminum isopropylate, mono-sec-butoxyaluminum diisopropylate, aluminum-sec- Chireto, aluminum alcoholates of aluminum ethylate or the like can be used, may be used in combination one or more of them.

  The additive is preferably used in an amount of 50 parts by mass or less based on 100 parts by mass of the total amount of the heat resistant resin (B) and the heat resistant resin (C). There exists a tendency for the physical property of resin films, such as heat resistance and mechanical strength, to improve that the compounding quantity of the said additive is 50 mass parts or less.

  Next, a method for forming a resin film using the resin paste according to the present embodiment and the resulting resin film will be described with reference to FIG.

  The method for forming a resin film according to the present embodiment includes a step of screen-printing the resin paste according to the present embodiment on a substrate, and a step of heating the resin paste after screen printing at 100 to 450 ° C. . FIG. 1 is a cross-sectional view schematically showing the state of the resin film in each step in the method for forming a resin film according to this embodiment.

(A) Screen printing process On the base material 1, the resin paste which concerns on the said embodiment is screen-printed. In the resin paste, the heat resistant resin (C) 3 is dispersed in the solution 2 containing the first polar solvent (A1), the second polar solvent (A2), and the heat resistant resin (B) at room temperature. State. The substrate 1 is, for example, silicon, and an emulsion layer may be formed on the substrate surface.

  A mesh plate and a squeegee used for a screen printing machine can be used without particular limitation, but a rubber squeegee is suitable for application of the resin paste according to the present embodiment.

(B) Heating process The resin paste after screen printing is heated at 100 to 450 ° C. Heating can be performed by a known method. In this step, the heat resistant resin (C) 3 is dissolved in the solution 2 containing the first polar solvent (A1), the second polar solvent (A2), and the heat resistant resin (B). The second polar solvent (A2) and the first polar solvent (A1) are volatilized in this order, and the resin film 4 is formed.

  The heating temperature is preferably 150 to 400 ° C, and more preferably 150 to 350 ° C. When the temperature is lower than 100 ° C., the solvent hardly evaporates, and the heat resistant resin (C) 3 includes the first polar solvent (A1), the second polar solvent (A2), and the heat resistant resin (B). In many cases, it does not dissolve in the solution 2, and the surface flatness of the resulting resin film tends to be lowered. When heated at a temperature exceeding 450 ° C., voids may occur in the resin film 4 due to outgassing.

  When at least one of the heat resistant resin (B) and the heat resistant resin (C) contains a polyimide resin precursor, it is heated at 350 ° C. or more, specifically 350 to 450 ° C., in order to advance imidization. Thus, it is preferable to cure the resin. If it is less than 350 degreeC, there exists a tendency for the reaction progress speed of imidation to become slow.

  The resin film 4 has extremely high flatness and a surface roughness of 2 μm or less. In addition, the surface roughness of the resin film in this invention refers to arithmetic mean roughness Ra. Arithmetic average roughness Ra is extracted from the roughness curve only the reference length (L) in the direction of the average line, the X-axis in the direction of the average line of the extracted portion, the Y-axis in the direction of the vertical magnification, When the roughness curve is represented by y = f (x), the value obtained by the following formula is represented in micrometers (μm). That is, Ra is a value represented by the following formula (1).

  Although the resin film 4 can be used for a semiconductor device or a solar cell, the glass transition temperature Tg of the resin film is preferably 180 ° C. or higher and the thermal decomposition temperature is 300 ° C. or higher from the viewpoint of the usage mode. Is preferred.

  Since the resin film 4 has sputtering resistance, plating resistance, and alkali resistance required in the step of forming the rewiring, it is preferably used for a semiconductor device. Further, since the amount of warpage of the silicon wafer can be reduced by using the resin film 4, it is possible to expect an improvement in yield in the manufacture of semiconductor devices, and an improvement in productivity is possible.

  The semiconductor device screen-prints the resin paste according to the present embodiment on a semiconductor substrate on which a plurality of wirings having the same structure are formed, and heats to form a resin film, and if necessary, on the semiconductor substrate on the resin film It can be manufactured by forming a wiring electrically connected to the electrode, forming a protective film on the wiring or the resin film, forming an external electrode terminal on the protective film, and dicing. Although there is no restriction | limiting in particular as said semiconductor substrate, For example, a silicon wafer etc. are mentioned.

  Moreover, since the resin film 4 is excellent in insulation, it is suitably used for an insulating film or a protective film of a solar cell. Particularly, it is useful for a back electrode type (back contact type) solar cell. Examples of the back electrode type (back contact type) structure include an MWT structure (Metal Wrap Through), an EWT structure (Emitter Wrap Through), and an IBC structure (Interdigitated Back Contact). The back electrode type (back contact type) solar cell has a structure in which the positive and negative electrodes are concentrated on the back surface of the light receiving surface and are close to each other for the purpose of improving electrical conversion efficiency. is there.

  The insulating film or protective film of the solar cell is obtained by, for example, screen-printing and heating the resin paste according to the present embodiment on a substrate formed with a plurality of positive electrodes and negative electrodes and removing the electrodes. Can be manufactured by forming a resin film. Although there is no restriction | limiting in particular as said solar cell substrate, For example, a silicon wafer etc. are mentioned. The resin paste according to this embodiment may form a resin film by a dispensing method other than screen printing, a coating method, or the like.

  FIG. 2 is a top view schematically showing a process of manufacturing the back electrode type solar cell with the MWT structure according to the present embodiment, and FIG. 3 manufactures the back electrode type solar cell with the MWT structure according to the present embodiment. It is an end view which shows the process to do typically. FIG. 3 schematically shows an end surface between A and B in FIG.

  First, a substrate 20 having a plurality of positive electrodes 13 and a plurality of negative electrodes 14 formed with aluminum wirings 12 formed on the back surface 11b of the silicon wafer 11 at a predetermined interval is prepared (FIG. 2 and FIG. )reference). Here, the plus electrode 13 is formed on the back surface 11b of the silicon wafer 11, and the minus electrode 14 is formed so as to penetrate from the light receiving surface 11a of the silicon wafer 11 to the back surface 11b. Further, the negative electrode 14 and the aluminum wiring 12 are not in contact with each other, and there is a gap between the negative electrode 14 and the aluminum wiring 12. On the other hand, the plus electrode 13 and the aluminum wiring 12 are in contact with each other. Next, a resin paste is screen-printed on the aluminum wiring 12 so that the end of the negative electrode 14 is exposed, and heated to form the resin film 4 (see FIGS. 2 and 3B). The resin film 4 is filled between the aluminum wiring 12 and the negative electrode 14. Thereafter, a Tab wiring 15 is formed on the negative electrode 14 and the positive electrode 13 so as to cover a part of the resin film 4 (see FIGS. 2 and 3C). Since the tab wiring 15 formed on the negative electrode 14 has the resin film 4, it does not contact the aluminum wiring 12 on the positive electrode 13 side, and no electron loss occurs between the two electrodes. The positive electrode 13 and the negative electrode 14 are preferably formed from a material mainly containing silver.

  FIG. 4A is a top view schematically showing an example of a back electrode type solar cell having an IBC structure according to this embodiment, and FIG. 4B is a cross-sectional view taken along a line CD in FIG. It is a figure which shows an end surface typically.

  A back electrode type solar cell 30 having an IBC structure shown in FIG. 4 includes a silicon wafer 21 having a light receiving surface 21a and a back surface 21b, a plurality of positive electrodes 23 and negative electrodes 24 formed on the back surface 21b at predetermined intervals, The resin film 5 covers the silicon wafer 21 so that the ends of the plus electrode 23 and the minus electrode 24 are exposed. Of the silicon wafer 21, the portion in contact with the positive electrode 23 is the p layer 27, and the other portion is the n layer 26. The resin film 5 can be formed by the same method as the resin film 4 in the back electrode solar cell having the MWT structure.

  Fig.5 (a) is a top view which shows typically an example of the back electrode type solar cell of the EWT structure concerning this embodiment, FIG.5 (b) is between EF in Fig.5 (a). It is a figure which shows an end surface typically.

  A back electrode type solar cell 40 having an EWT structure shown in FIG. 5 includes a silicon wafer 31 having a light receiving surface 31a and a back surface 31b, a plurality of positive electrodes 33 and negative electrodes 34 formed on the back surface 31b at predetermined intervals. The resin film 6 covers the silicon wafer 31 so that the ends of the plus electrode 33 and the minus electrode 34 are exposed. A portion of the silicon wafer 31 on which the negative electrode 34 is formed is provided with a through hole 36 toward the light receiving surface 31a. The resin film 6 can be formed by the same method as the resin film 4 in the back electrode solar cell having the MWT structure.

  FIG. 6 is a schematic diagram showing a method for producing a resin film by screen printing. First, a substrate 45 to be printed, a mesh 42 on which a predetermined portion of the back surface is coated with the emulsion 41, and a rubber squeegee 44 for moving the resin paste 43 of this embodiment along the printing direction A are prepared. (FIG. 6A). When the rubber squeegee 44 is moved along the printing direction A on the mesh 42, the resin paste 43 is applied to the substrate 45 through a portion of the mesh where the emulsion 41 is not applied (FIG. 6B). A resin film 46 is obtained by heating the applied resin paste 43 (FIG. 6C).

  When applying the resin paste to the back surface of the back electrode type solar cell, apply the emulsion to the back surface of the mesh at the location corresponding to the portion so that the resin paste is not applied to the portion where the electrode is formed. That's fine.

  Since the resin paste of this embodiment is excellent in flatness, cracks are hardly generated even in a thin film, and the reliability is also excellent. In addition, even with respect to mesh marks generated during screen printing, the resin film after drying has a uniform film thickness due to high flatness, so that conduction from the thinnest part of the insulating film is prevented and the electrical characteristics are excellent. The resin film according to this embodiment preferably has a dry film thickness of 1 to 100 μm, more preferably 1 to 20 μm, and particularly preferably 1 to 10 μm.

  If the flatness is poor, cracks are likely to occur, and a power generation effect cannot be obtained by conducting electricity between the electrodes. Moreover, since unevenness is formed in the surface of the resin film due to the mesh marks, there is a possibility that electrical conduction is caused from the thinnest part of the resin film recess and electrical characteristics are lowered.

  Regarding the resin film according to the present embodiment, the surface roughness is preferably Ra = 0.2 μm or less, and more preferably 0.1 μm or less.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. In this example, gel permeation chromatography was performed under the following conditions.
Eluent: NMP, H ₃ PO ₄ (0.06 mol / L)
Column type: Shodex solvent displacement separation column GPC KD-806M manufactured by Showa Denko K.K.
Standard material for preparing calibration curve: Standard polystyrene

<Synthesis Example 1: Synthesis of heat resistant resin (B)>
2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter referred to as “nitrogen”) in a 5-liter four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a cooling tube with an oil / water separator. , BAPP) 650.90 g (1.59 mol) was added, and 360.86 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) was added and dissolved. Next, 384.36 g (1.83 mol) of trimellitic anhydride chloride (hereinafter referred to as TAC) was added while cooling so as not to exceed 20 ° C.
After stirring at room temperature for 1 hour, 215.90 g (2.14 mol) of triethylamine (hereinafter referred to as TEA) was added while cooling so as not to exceed 20 ° C., and reacted at room temperature for 1 hour to obtain a polyamic acid varnish. Manufactured. The resulting polyamic acid varnish was further subjected to a dehydration reaction at 180 ° C. for 6 hours to produce a polyamideimide resin varnish. A precipitate obtained by pouring the varnish of the polyamideimide resin into water was separated, pulverized, and dried to obtain a polyamideimide resin powder (MPAI-1) (in the formula (1), X is the formula (a)) Represented polyamideimide). It was 55000 when the weight average molecular weight of the obtained polyamideimide resin (MPAI-1) was measured in terms of standard polystyrene using gel permeation chromatography (hereinafter referred to as GPC). In addition, this polyamideimide resin powder (MPAI-1) has a mass ratio of 7: 3 or 9: 25% at a temperature ratio of the first polar solvent (A1) and the second polar solvent (A2) in Examples described later. 1 was soluble in solution.

<Synthesis Example 2: Synthesis of heat resistant resin (C)>
In a 1-liter four-necked flask equipped with a thermometer, a stirrer, a nitrogen inlet tube, and a cooling tube with an oil / water separator, 69.72 g (170.1 mmol) of BAPP was placed in a nitrogen stream and dissolved by adding 69.52 g of NMP. did. Next, TAC25.05 g (119.0 mmol) and 3,4,3 ′, 4′-benzophenonetetracarboxylic dianhydride (hereinafter referred to as BTDA) 25.47 g (79 0.1 mmol) was added.
After stirring at room temperature for 1 hour, 14.42 g (142.8 mmol) of TEA was added while cooling so as not to exceed 20 ° C., and reacted at room temperature for 1 hour to prepare a polyamic acid varnish. The resulting polyamic acid varnish was further subjected to a dehydration reaction at 180 ° C. for 6 hours to produce a polyimide resin varnish. A precipitate obtained by pouring the varnish of the polyimide resin into water was separated, pulverized and dried to obtain a polyimide resin powder (PAI-1) (in the formula (20), X is represented by the formula (a). Polyimide). It was 39000 when the weight average molecular weight of the obtained polyimide resin (PAI-1) was measured in standard polystyrene conversion using GPC. In addition, although this polyimide resin powder (PAI-1) was soluble in the 1st polar solvent (A1) in the Example mentioned later at 25 degreeC, it is insoluble in the 2nd polar solvent (A2). And insoluble in a 7: 3 or 9: 1 mass ratio of the first polar solvent (A1) and the second polar solvent (A2). The average particle size was about 1 μm.

<Preparation of resin pastes (P-1) to (P-7)>
Example 1
In a 0.5 liter four-necked flask equipped with a thermometer, stirrer, nitrogen inlet tube and condenser tube, 92.4 g of γ-butyrolactone as the first polar solvent (A1) under a nitrogen stream, second polar solvent 39.6 g of diethylene glycol diethyl ether as (A2), 30.8 g of polyamideimide resin powder (MPAI-1) obtained in Synthesis Example 1 as heat resistant resin (B), and obtained in Synthesis Example 2 as heat resistant resin (C) 13.2 g of the obtained polyimide resin powder (PAI-1) was added and the temperature was raised to 180 ° C. while stirring. After stirring at 180 ° C. for 2 hours, heating was stopped and the mixture was allowed to cool with stirring to obtain a yellow composition. A filter paste KST-47 (manufactured by Advantech Co., Ltd.) was filled, and a silicone rubber piston was inserted, followed by pressure filtration at a pressure of 3.0 kg / cm ² to obtain a resin paste (P-1).

(Example 2)
Resin paste (P-2) was obtained in the same manner as in Example 1 except that butyl cellosolve acetate was used as the second polar solvent (A2).

(Example 3)
Resin paste (P-3) in the same manner as in Example 1 except that 118.9 g of γ-butyrolactone was used as the first polar solvent (A1) and 13.2 g of diethylene glycol diethyl ether was used as the second polar solvent (A2). Got.

(Example 4)
A resin paste (P-4) was obtained in the same manner as in Example 3 except that butyl cellosolve acetate was used as the second polar solvent (A2).

(Comparative Example 1)
Resin paste (P-5) was obtained in the same manner as in Example 1 except that triethylene glycol dimethyl ether was used instead of diethylene glycol dimethyl ether.

(Comparative Example 2)
Resin paste (P-6) in the same manner as in Example 1 except that 66.1 g of γ-butyrolactone was used as the first polar solvent (A1) and 66.1 g of diethylene glycol diethyl ether was used as the second polar solvent (A2). Got.

(Comparative Example 3)
Resin paste (P-7) was prepared in the same manner as in Example 1 except that 66.1 g of γ-butyrolactone was used as the first polar solvent (A1) and 66.1 g of butyl cellosolve acetate was used as the second polar solvent (A2). Obtained.

<Evaluation>
(Viscosity and thixotropy coefficient (TI value))
The viscosity and thixotropy coefficient (TI value) of the resin pastes obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were measured with a high viscosity viscometer RE-80U (manufactured by Toki Sangyo Co., Ltd.). The viscosity was measured at a rotational speed of 0.5 rpm, and the thixotropy coefficient (TI value) was calculated as the ratio of the measured viscosity value at a rotational speed of 10 rpm to the measured viscosity value at a rotational speed of 1 rpm.

(Non-volatile content)
Several g of the resin pastes obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were weighed on a metal petri dish. The resin paste was dried at 150 ° C. for 1 hour and at 250 ° C. for 2 hours, then weighed on a metal petri dish, and a non-volatile content concentration (hereinafter referred to as NV) was calculated based on the following formula (2).
NV (%) = (mass after drying the resin paste (g) / mass of the resin paste before heating (g)) × 100 (2)

(resolution)
An emulsion having a circular opening having a diameter of 300 μm or 500 μm was coated on an 8-inch silicon wafer, and the resin pastes obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were applied to a screen printing machine (Nerong Precision Industry ( Co., Ltd., LZ-0843 with alignment device), mesh plate (manufactured by NBC Meshtec, V380, wire diameter 23 μm, thickness 43 μm, emulsion thickness 20 μm) and MN rubber squeegee (manufactured by Neurong Precision Industry Co., Ltd.) Was used for screen printing so as to leave the opening.
After the screen printing, the resin film obtained by drying and curing by heating for 10 minutes on a hot plate heated to 100 ° C. and further heating for 30 minutes in an oven heated to 250 ° C. The average value of the diameters (hole diameters) of the six holes in the printed part of the resin paste corresponding to the emulsion openings was measured. The holes in Examples 1 and 2 and Comparative Examples 1 and 3 were formed in the emulsion openings having a diameter of 300 μm. In addition, the hole portions of Examples 3 and 4 were formed in an emulsion opening having a diameter of 500 μm. In addition, the variation indicates the value of the standard deviation at the observation location (n = 6), and the smaller the better.
Specifically, the hole diameter of the printing unit was observed with the above universal projector, and the hole diameter was calculated by a three-point input format using a data processing system (Nikon Corporation, DP-202). The average value of n = 6 was defined as the resolution.

(Dry film thickness)
About the resin film produced in the evaluation of resolution, the dry film thickness was measured using the micrometer (product made from Mitutoyo Corporation, model number MDE-25PJ).

(Surface roughness)
About the resin film obtained by heating as described above after screen printing, a stylus type surface roughness measuring instrument (manufactured by Kosaka Laboratory, model number: SE1700-18D, measuring distance: 10.0 mm, feed rate) : 0.5 mm / s), the surface roughness (arithmetic average roughness: Ra) of the resin film was measured.

  Types of first polar solvent (A1) and second polar solvent (A2) contained in resin pastes (P-1) to (P-7) obtained in Examples 1 to 4 and Comparative Examples 1 to 3 , Boiling point, mass ratio of the first polar solvent (A1) and the second polar solvent (A2), and the resin pastes (P-1) to (P-7) and the resin film obtained using them Various evaluation results are shown in Tables 1 and 2. In addition, the resin paste obtained in Comparative Example 2 was in a chewing gum shape, and the viscosity and TI value could not be measured, and screen printing could not be performed.

  From Tables 1 and 2, the resin films obtained from the resin pastes of Examples 1 to 4 are comparative examples in which the boiling point temperature is higher than that of the first polar solvent (A1) as the second polar solvent (A2). Compared to the resin films obtained by the resin pastes of Comparative Examples 2 and 3 in which the ratio of 1 or A1: A2 is 5: 5, it was revealed that precise resolution was obtained and surface flatness was particularly excellent. .

  DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Solution containing 1st polar solvent (A1), 2nd polar solvent (A2), and heat resistant resin (B), 3 ... Heat resistant resin (C), 4, 5, 6 ... resin film, 11, 131 ... silicon wafer, 12 ... aluminum wiring, 13, 23, 33 ... positive electrode, 14, 24, 34 ... negative electrode, 15 ... TAB wiring, 20 ... substrate, 30 ... back electrode of IBC structure Type solar cell, 36 ... through-hole, 40 ... back electrode solar cell with EWT structure, 41 ... emulsion, 42 ... mesh, 43 ... resin paste, 44 ... rubber squeegee, 45 ... substrate, 46 ... resin film.

Claims (8)

A mixed solvent comprising a first polar solvent (A1) and a second polar solvent (A2) having a boiling point lower than that of the first polar solvent (A1) in a mass ratio of 6: 4 to 9: 1; ,
A heat-resistant resin (B) soluble in the mixed solvent at room temperature;
A heat-resistant resin (C) that is soluble in the first polar solvent (A1), insoluble in the second polar solvent (A2), and insoluble in the mixed solvent at room temperature. Including
A resin paste in which the heat resistant resin (C) is dispersed in a solution containing the mixed solvent and the heat resistant resin (B).   The resin paste according to claim 1, wherein a difference between a boiling point of the first polar solvent (A1) and a boiling point of the second polar solvent (A2) is 10 to 100 ° C.   The heat resistant resin (B) and the heat resistant resin (C) are each independently at least one selected from a polyamide resin, a polyimide resin, a polyamideimide resin, or a precursor of a polyimide resin and a polyamideimide resin. The resin paste according to claim 1 or 2.   The said heat resistant resin (C) disperse | distributed in the said solution is a resin paste as described in any one of Claims 1-3 which is a particulate form with an average particle diameter of 50 micrometers or less. Screen-printing the resin paste according to any one of claims 1 to 4 on an electrode side surface of a substrate having a negative electrode and a positive electrode;
The manufacturing method of the solar cell including the process of heat-drying the said resin paste screen-printed at 100-450 degreeC.   A solar cell manufactured by the method according to claim 5.   It forms by the method of including the process of screen-printing the resin paste as described in any one of Claims 1-4 on a base material, and the process of heating the said screen-printed resin paste at 100-450 degreeC. A resin film having a surface roughness of 2 μm or less.   A semiconductor device comprising the resin film according to claim 7.

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