JPH0927674A - Photosensitive resin composition, hardened film thereof, and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board where no solder ball is left on a solder resist film of the circuit board when cleaningless/low residue flux is used. SOLUTION: Photosensitive resin composition which comprises optical photopolymerizing photosensitive resin possessed of carboxylic group and/or onium group photopolymerizing reactive diluent, photopolymerizing initiator, thermosetting component, and inorganic powder 2 to 20μm in average diameter, a solder resist film such as a cured film of photosensitive resin composition, and a circuit board where the solder resist film is used are provided. By this setup, cleaningless/low residue flux is applied all over the solder resist film uniformly, and a soldering operation can be carried out without leaving solder balls. The solder resist film is enhanced in properties such as heat resistance and chemical resistance by adding thermosetting ingredient, improved in developing properties because it is possessed of carboxylic group, and capable of being developed through only water because it is possessed of onium group. A circuit board excellent in reliability and productivity can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition for forming a solder resist film, a cured coating film thereof, and a circuit board using the same.

[0002]

2. Description of the Related Art A printed circuit board as a circuit board is, for example, a copper clad laminated board on which a pattern of circuit wiring is formed, on which electronic parts can be mounted to form one circuit unit. However, to mount capacitors, resistors, etc. as electronic parts,
These parts are soldered and connected and fixed to the copper foil lands of the circuit wiring pattern, that is, the soldering lands. At this time, soldering should be performed after forming an insulating film called a so-called solder resist film on the entire surface of the substrate including other circuit wiring parts excluding the soldering land part, and do not connect each wiring. The soldering process is performed after the parts are not connected by solder and the copper surface is not corroded. In order to solder the electronic components to the printed circuit board in this way, for example, chip-shaped electronic components having electrodes on both ends are arranged at predetermined positions on the printed circuit board so that the electrodes on both ends are located on the soldering lands. Then, temporarily soldering, and then soldering by making contact with molten solder that jets this temporarily electronic component, so-called jet soldering method or applying solder paste to soldering land, Similarly, a so-called reflow soldering method is used in which electrodes of electronic components are positioned and heated to melt and solder solder powder of a solder paste.

No matter which of these soldering methods is used, flux is applied and then molten solder is brought into contact with the solder paste or solder paste is applied. This prevents the solder foil from being poorly soldered due to oxidation of the copper foil on the soldering land. That is, the soldering land of the printed circuit board is 200 ° C.
Since it is heated to 300 ° C, not only when the surface is exposed but also when a protective film is formed on the surface, when the flux is applied during soldering, the film blocks oxygen. It prevents oxidation of the copper foil, reduces the oxides that have already formed, and wets the molten solder well. As such a flux, a rosin-based flux is often used, and its composition is mainly composed of a rosin-based resin, to which an amine halogen salt, an activator such as an organic acid is added, and these are dissolved in an alcohol-based solvent. It was done. With a commonly used flux whose solid content is as high as 10%, the film thickness can be increased to several μm or more even if the flux is applied by a dipping method, a method of spraying with bubbles, or another method. Therefore, even when the coating surface is relatively likely to cause coating unevenness, the entire coating can be well covered with the coating film, and a phenomenon such as coating unevenness does not occur. However, the coating film also contains an ionic substance, and since the rosin-based resin having a softening point of about 100 ° C. is used, it may be soft and dust may adhere to it. In order to make the insulation more reliable, it is necessary to wash it.
Therefore, it is necessary to use an organic solvent for cleaning.

However, in recent years, the release of the fluorine-based solvent into the atmosphere has become an environmental problem, and the above-mentioned cleaning accompanied by the discharge of the organic solvent in accordance with the movement of so-called defronization, which avoids using the solvent, is carried out. It is possible to make products without leaving the flux film, that is, without soaking, so-called flux-free cleaning and low-residue is being promoted. To that end, flux with a low solid concentration such as 2% Is being used. However, this is because the film thickness of the coating film is thin and is easily affected significantly by the surface physical properties of the coating surface, and even when the coating surface is a solder resist film, the coating film is not formed due to its surface physical properties. May cause parts. For example, when soldering with a jet soldering machine, the solder may have several tens of μ on the flux film.
m may remain as a spherical so-called solder ball. Even if oxidation occurs, the solder ball is reduced by the reducing agent in the flux, and the adhesive force to the jet molten solder is the adhesive force to the flux film or the flux adhered to the solder ball. It is possible to prevent the solder from remaining on the flux film or the solder resist film because it is absorbed in the flow more than the adhesive force of the film to the solder resist film, but the flux film is not formed and the solder resist film is not formed. Although the molten solder is essentially a surface that is difficult to wet in the exposed area, when solder balls are generated, the surface is oxidized and the adhesive force between the oxide and the solder resist film is jetted. Outstanding the adhesion to molten solder, the oxide of the solder ball is Not easily absorbed by the record, easily happen that remain.

[0005]

As described above, the solder balls are likely to remain on the solder resist film on which the flux film is not formed. As the solder resist film, an ultraviolet curable resin or a thermosetting resin is used. A coating film made of resin is used, and recently, with the increase in wiring density of printed circuit boards that meet the demand for high-density mounting of electronic components on printed boards in order to make electronic devices smaller and more compact. Since the wiring density between the soldering lands is also increased, the solder resist film is required to have high resolution and high accuracy.
From the screen printing method, which has limited resolution and fidelity, there has been proposed a method of using a liquid photosolder resist composition having good positional accuracy and good coverage of conductor edges such as soldering lands. For example, JP-A-50-14443
No. 1 and JP-A No. 51-40451, a photosensitive composition comprising a bisphenol type epoxy acrylate, a sensitizer, a thermosetting epoxy compound, and a curing agent thereof is applied to the entire surface of a printed circuit board by screen printing. Then
A method of forming a solder resist film by evaporating the solvent, exposing it to a negative film having a wiring pattern, exposing it, and then developing by dissolving and removing the unexposed portion of the non-image portion with the solvent is disclosed.

However, in order to avoid the risk of environmental pollution and fire caused by using such an organic solvent as a developing solution or a photosensitive composition containing the organic solvent itself, or the developing solution of the organic solvent. A solder resist film that uses a photosensitive composition with a composition similar to this developed that can be developed with a dilute alkaline solution uses the above-mentioned non-cleaning, low-residue type flux especially for its glossy film. In this case, there is a problem in that coating unevenness easily occurs in the uncoated portion. When uneven coating occurs and the solder balls remain on the solder resist film in this way, the solder balls move during the handling of the product, and as described above, the wiring density of a recent printed circuit board that is as close as 100 μm. In particular, there is a problem of short-circuiting between the wirings, and in order to avoid this, the solder balls must be removed. For all wirings where thousands of components are mounted on one printed circuit board It is not easy to do this, and there are problems not only in productivity but also in reliability. In addition, a conventional dilute alkaline aqueous solution development type photosensitive resin includes, for example, a reaction product of a novolac type epoxy resin and an unsaturated monocarboxylic acid, which is reacted with a polybasic acid anhydride, and a photopolymerization starter. Photoresist resist composition containing agent, diluent and epoxy compound (Japanese Patent Publication No. 1-54390)
Or a copolymer of (meth) acrylic acid ester and (meth) acrylic acid to which a (meth) acrylic acid ester having a terminal epoxy group is added to a part of a carboxyl group, a diluent and a photopolymerization initiator And a one-component photo solder resist (Japanese Patent Application No. 1-311710) and a photosensitive composition containing a novolac type resin and an onium compound (Japanese Patent Application Laid-Open No. 60-175045 and Japanese Patent Application Laid-Open No. 3-154).
No. 059 gazette) and the like have been proposed, but these are ones that enable development with a dilute alkaline aqueous solution by introducing a carboxyl group into a photosensitive component or by using an onium type photosensitive component, and a printed wiring board. There is still a problem for large-scale production, such as the fact that an organic solvent is still required when applying it to the product, and it is necessary to consider the treatment of the alkaline solution after using it for drainage. There is also proposed a photosensitive resin composition which does not require the use of an organic solvent or an aqueous alkali solution at the time of development and can be developed only with water, and which can form a highly sensitive and highly accurate pattern (Japanese Patent Laid-Open No. 6-59448). However, even in this case, as in the case described above, it is not possible to avoid the residue of the brick pole due to coating unevenness, and improvement thereof is desired. In addition, in order to mount components and members on the printed circuit board with high density and high precision in response to the increasingly demanding recent demands, when soldering is performed while temporarily fixing the components and members mounted on the printed circuit board. Is to prevent the parts from falling off by increasing the adhesive strength of the adhesive used.
In the case of soldering a large number of parts to a printed circuit board, an optical 3D automatic visual inspection machine that inspects whether the joints are acceptable or not when inspecting the number of points where the prescribed soldering is not performed. Reduces the false alarm rate that the reflection of light impairs the judgment of the success of the bonding when the solder resist film around it is glossy even if the bonding is successful, and the inspection device that inspects whether the predetermined operation of the circuit is successful or not. ICT pin (contact pin with in-circuit tester circuit) Improving contact property is required at an even higher level, and improvement to meet this is demanded.

A first object of the present invention is to provide a photosensitive resin composition capable of forming a cured coating film such as a solder resist film having no coating unevenness of a liquid such as a non-cleaning and low residue type flux, and a cured coating thereof. It is intended to provide a circuit board using a film and a cured coating film thereof. A second object of the present invention is, for example, a solder resist film in which a molten metal ball such as a solder ball is unlikely to be formed during soldering even if a coating composition having a low solid content such as a non-cleaning / low residue type flux is used. Another object of the present invention is to provide a photosensitive resin composition capable of forming a cured coating film such as, a cured coating film thereof, and a circuit board using the cured coating film. A third object of the present invention is to provide a photosensitive resin composition capable of forming a solder resist film or the like with high resolution and high accuracy, a cured coating film thereof, and a circuit board using the cured coating film. It is in. A fourth object of the present invention is a photosensitive resin capable of forming, for example, a solder resist film having excellent heat resistance, adhesion to a coated surface, chemical resistance, solvent resistance, electrical characteristics and mechanical characteristics. It is intended to provide a composition, a cured coating film thereof, and a circuit board using the cured coating film. A fifth object of the present invention is to provide a photosensitive resin composition which can be developed with a dilute alkaline solution to form a solder resist film or the like,
It is intended to provide a cured coating film and a circuit board using the cured coating film. A sixth object of the present invention is to provide a photosensitive resin composition capable of forming a solder resist film or the like by being developed only with water, a cured coating film thereof, and a circuit board using the cured coating film. To provide. A seventh object of the present invention is to improve the adhesive force of the adhesive for temporarily fixing parts and members such as surface mount parts and strap wires, and reduce the false alarm rate of a three-dimensional automatic appearance inspection machine. It is to provide a photosensitive resin composition capable of obtaining a cured coating film such as a solder resist film capable of improving the ICT pin contact property, a cured coating film thereof, and a circuit board using the cured coating film. An eighth object of the present invention is to provide a photosensitive resin composition that is less likely to cause environmental pollution and less likely to cause a fire, a cured coating film thereof, and a circuit board using the cured coating film. A ninth object of the present invention is to provide a circuit board before mounting an electronic component, which can improve soldering productivity and reliability. The tenth object of the present invention is to
An object of the present invention is to provide a circuit board after mounting electronic components, which can be obtained at low cost without impairing the reliability of the circuit function, with high productivity.

[0008]

In order to solve the above problems, the present invention provides (1) a photopolymerizable photosensitive resin having at least one of a carboxyl group and an onium-containing group, and a photopolymerizable reactive diluent. , Photopolymerization initiator and average particle size is 2μ
A photosensitive resin composition containing an inorganic powder of m to 20 μm is provided. The present invention also provides (2),
The photosensitive resin composition of the above (1) containing a thermosetting component, (3), the photosensitive resin composition of the above (1) or (2), wherein the inorganic powder is amorphous silica and contained at least 10% by weight. (4), a photopolymerizable photosensitive resin having a carboxyl group is a reaction product of an epoxy resin and 0.3 to 1.2 mol of an α, β unsaturated carboxylic acid per epoxy equivalent of the epoxy resin. A prepolymer which is a reaction product of an epoxy resin / α, β unsaturated carboxylic acid ester and 0.2 to 1.0 mol of a polybasic acid and / or an anhydride thereof per epoxy equivalent of the epoxy resin. A certain photosensitive resin composition of the above (1), (2) or (3),
(5), the epoxy resin is an epoxy resin containing at least two terminal epoxy groups, or contains a monomer represented by the following general formula [Chemical formula 1] and a monomer represented by the following general formula [Chemical formula 2] The photosensitive resin composition of (4), which is a copolymer of a plurality of monomers,

[0009]

(In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an aliphatic hydrocarbon group having 1 to 6 carbon atoms.)

[0010]

(In the formula, R ₃ represents a hydrogen atom or a methyl group, and R ₄ represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group having 1 to 12 carbon atoms.)

(5) The photopolymerizable photosensitive resin containing an onium group comprises at least one monomer selected from alkyl acrylate and alkyl methacrylate and an epoxy group-containing acrylate and an epoxy group-containing methacrylate. An onium group-containing prepolymer in which an acryloyl group or a methacryloyl group is introduced as a part of the epoxy group of a copolymer with at least one epoxy group-containing monomer selected from the above, and an onium group-containing group is introduced as the rest. (1),
Among the photosensitive resin composition of (2) or (3), (7), at least one monomer selected from alkyl acrylate and alkyl methacrylate, and epoxy group-containing acrylate and epoxy-containing methacrylate. The molar ratio with at least one epoxy group-containing monomer selected from
The photosensitive resin composition according to (6) above, which is 0:60 to 60:20, (8), and 20 to 8 epoxy groups in the copolymer.
80 mol of acryloyl group or methacryloyl group in 0 mol%
The photosensitive resin composition of (6) or (7), wherein the onium-containing group is introduced in an amount of ˜20 mol%, (9), and the prepolymer having an average molecular weight of 20,000 to 70,000 (6), (7) or the photosensitive resin composition of (8), (1
0), the photopolymerizable reactive diluent is an acrylate and / or methacrylate having two or more polymerizable double bonds in one molecule, the photosensitive resin composition according to any one of the above (1) to (9), (11), the photosensitive resin composition according to any one of the above (2) to (10), wherein the thermosetting component contains a thermosetting epoxy compound, (12), and light per 100 parts by weight of the onium group-containing prepolymer. Polymerization initiator 0.5-5
The photosensitive resin composition according to any one of the above (1) to (11), which contains 0 part by weight and 2 to 40 parts by weight of a photopolymerizable reactive diluent, (13) a solder resist ink for a circuit board, Photosensitivity obtained by photo-curing and heat-curing the coating film of the photosensitive resin composition according to any one of (1) to (12), (14), and the photosensitive composition according to any one of (1) to (12) above. Cured coating film of resin composition (15), cured coating film of the above (14) having a surface roughness of 2.5 to 10 μm, (1
6) is a coating film of the photosensitive composition according to the above (13),
A circuit board having a photo-cured or photo-cured and heat-cured solder resist film, (17), a circuit board according to the above (16) in which the surface roughness of the solder resist film is 2.5 to 10 μm, (18), A circuit board according to (16) or (17) before mounting an electronic component, (19), and a circuit board according to (16) or (17) after mounting an electronic component.

In the present invention, the "photopolymerizable photosensitive resin having a carboxyl group" contained in the photosensitive resin composition.
As an oligomer or polymer having an epoxy group, for example, an oligomer or polymer which is an epoxy resin containing at least two terminal epoxy groups,
0.3-1.per 1 epoxy equivalent of the epoxy resin.
2 moles, especially 0.3 to 0.9 when the epoxy resin is not a copolymer type epoxy resin described later.
To the epoxy resin / α, β unsaturated carboxylic acid ester, which is a reaction product of α, β unsaturated carboxylic acid, for example, unsaturated monocarboxylic acid, 0.2 to 1. A prepolymer obtained by reacting 0 mol of a polybasic acid and / or its anhydride to add a carboxyl group to a side chain is mentioned. There are no particular restrictions on the epoxy equivalent of the epoxy group-containing oligomer or polymer.
000 or less, preferably 100 to 500 is used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, brominated epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, aliphatic epoxy resin, phenol novolac type Epoxy resin, cresol novolac type epoxy resin, naphthalene novolac type epoxy resin, glycidyl amine type epoxy resin, bisphenol S modified novolac type polyfunctional epoxy resin, polyfunctional modified nopolak type epoxy resin, phenol and aromatic compounds having phenolic hydroxyl group Condensation product with aldehyde Epoxy resin, at least one monomer selected from alkyl acrylate and alkyl methacrylate, and at least one compound selected from epoxy group-containing (meth) acrylate And a copolymer of an epoxy group-containing monomer.

Examples of the copolymer include a copolymer of a monomer represented by the general formula [Chemical formula 1] and a plurality of monomers containing the monomer represented by the general formula [Chemical formula 2]. Examples of the monomer other than the monomers represented by the general formulas [Chemical Formula 1] and [Chemical Formula 2] include styrene and the like, and a method of carrying out this type of polymerization is usually used for the production thereof. Is used. Here, the compound of the general formula [Chemical formula 1] and the general formula [Chemical formula 2]
The molar ratio with the compound of is preferably 40:60 to 80:20. If the compounding amount of the compound represented by the general formula [Chemical Formula 2] is too small and the molar ratio is larger than 80:20, (meth) acrylic acid and further polybasic acid anhydride are added to the copolymer in the subsequent step. As a result of the addition amount being reduced, the ultraviolet curability of the prepolymer film and the developability of the film after curing with a dilute alkaline aqueous solution deteriorate, and conversely, the compound of the general formula [Chemical Formula 2] is compounded. When the amount is too large and the molar ratio is less than 40:60, the softening point of the prepolymer tends to be too low. Specific examples of the compound of the general formula [Formula 1] include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl and isohexyl esters of acrylic acid or methacrylic acid. Further, specific examples of the compound represented by the general formula [Chemical Formula 2] include glycidyl acrylate and glycidyl methacrylate.

To react this copolymer with, for example, an α, β unsaturated monocarboxylic acid such as (meth) acrylic acid, the (meth) acrylic acid is added in an amount of 0.8 to 1. A 2 mole reaction is carried out to obtain a copolymer epoxy resin / (meth) acrylic acid ester. The weight average molecular weight of a prepolymer obtained by reacting this copolymer epoxy resin / (meth) acrylic acid ester with a polybasic acid and / or its anhydride [liquid chromatography method by GPC (gel permeation chromatography) method] 20,000 to 70,000, and its softening point [TMA (thermal expansion and thermomechanical analysis) method] is 35 to 1
30 degreeC and the acid value of 50-150 are preferable. As the polybasic acid anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 3-ethylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, 3-methyltetrahydrophthalic acid Anhydrous, 4-
Methyltetrahydrophthalic anhydride, 3-ethyltetrahydrophthalic anhydride and the like are preferable. Polybasic acids obtained by hydrolyzing these polybasic acid anhydrides are also used, and these polybasic acids and their anhydrides may be used in combination. Further, aliphatic polybasic acids such as maleic acid and fumaric acid, and their anhydrides are also used for these. If the weight average molecular weight of the prepolymer is too low, the cured coating film of the photosensitive resin composition of the present invention has poor heat resistance, and if it is too high, the solubility in the photopolymerizable reactive diluent and workability deteriorate. There is a fear. Further, if the softening point is too low, since the tackiness remains after coating and drying the photosensitive resin composition of the present invention, a negative film may adhere to the coating during exposure, while if it is too high, ultraviolet rays are generated. The curability may deteriorate. Further, if the acid value is too low, after the photo-curing of the coating film of the photosensitive resin composition of the present invention, the removability of removing the film of the unexposed portion by the development treatment with a dilute aqueous alkali solution becomes poor, while if too high. The finally obtained cured film of the photosensitive resin composition of the present invention tends to have poor electrical properties and humidifying properties.

As the "onium group-containing photopolymerizable photosensitive resin", at least one monomer selected from alkyl acrylate and alkyl methacrylate and epoxy group-containing acrylate and epoxy group-containing An onium group-containing prepolymer in which an acryloyl group or methacryloyl group is introduced as a part of the epoxy group of a copolymer with at least one epoxy group-containing monomer selected from methacrylate and an onium group-containing group is introduced as the remainder Examples of the onium group-containing prepolymer include R ₂ in the general formula [Chemical Formula 1] having 1 to 6 carbon atoms.
In the above general formula [Chemical Formula 2], a monomer represented in the same manner except that each alkyl group and other alkyl groups are the same,
R ₄ is obtained by copolymerizing with an epoxy group-containing monomer represented in the same manner, except that R ₄ is an aliphatic hydrocarbon group having 1 to 12 carbon atoms or other aliphatic hydrocarbon group or aromatic hydrocarbon group. The following general formula [Chemical Formula 3]

[0016]

Embedded image (In the formula, R ₅ is a hydrogen atom or a methyl group.) An unsaturated fatty acid represented by the formula is reacted to introduce an acryloyl group or a methacryloyl group into a part of the glycidyl group, and then further reacted with an onium compound. And introducing an onium-containing group into the remaining glycidyl group.
At this time, the compounds represented by the general formulas [Chemical formula 1], [Chemical formula 2] and [Chemical formula 3] may be used alone or as a mixture of two or more kinds. Examples of the epoxy group-containing monomer represented by the general formula [Chemical Formula 2] include glycidyl acrylate, glycidyl methacrylate, (2-epoxyethyl) acrylate, (2-epoxyethyl) methacrylate, (4-epoxybenzyl) acrylate, ( Four
-Epoxy benzyl methacrylate etc. Also,
As specific compounds of the general formulas [Chemical Formula 1] and [Chemical Formula 2], the above-mentioned monomers can be mentioned.

The onium compound which reacts to introduce an onium-containing group is represented by the general formula [R ₆ S ⁺ ] X ^−.
(Wherein R ₆ is an alkyl group or an aryl group, X ⁻ is an anion), for example, a triphenylsulfonium salt, a tributylsulfonium salt,
General formula [Ar ₂ I ⁺ ] X ⁻ (where Ar is an aromatic cyclic group,
X ⁻ is an anion), an aryliodonium salt represented by
A phosphonium compound represented by the general formula [R ₇ P ⁻ ] X ⁻ (wherein R ₇ is an alkyl group or an aryl group, and X ⁻ is an anion), such as diphenyliodonium chloride or diphenyliodonium hexafluorophosphate,
For example, tetramethylphosphonium iodide, tetraethylphosphonium bromide and the like, represented by the general formula [R ₈ N ⁺ ] X ⁻
An ammonium compound represented by the formula (wherein R ₈ is an alkyl group or an aryl group, X ⁻ is an anion), such as tetramethylammonium chloride or tetraethylammonium chloride, is used.

When forming the onium group-containing prepolymer, the molar ratio of the monomer represented by the general formula [Chemical formula 1] to the glycidyl group-containing monomer represented by the general formula [Chemical formula 2] is It is preferable to select within the range of 40:60 to 80:20. If the proportion of the glycidyl group-containing monomer of the general formula [Chemical Formula 2] is smaller than this, the amount of the acryloyl group or methacryloyl group introduced will be small, and it will be difficult to cure the photosensitive resin composition with ultraviolet light. When this ratio is high, the softening point of the pattern film obtained by curing the coating film of the photosensitive resin composition is low, and tack is likely to occur. Also,
A copolymer of a monomer represented by the general formula [Chemical formula 1] and a glycidyl group-containing monomer represented by the general formula [Chemical formula 2], and an unsaturated fatty acid represented by the general formula [Chemical formula 3] It is preferable to select the use ratio of the glycidyl group and the unsaturated fatty acid in the copolymer in the range of 20:80 to 80:20. If the proportion of unsaturated fatty acids is less than this, it becomes difficult to cure the photosensitive resin composition with ultraviolet light, and if the proportion of unsaturated fatty acids is greater than this, the proportion of residual glycidyl groups is less, resulting in onium. The content of groups is reduced and the water solubility becomes insufficient.

In the reaction of the onium compound with the residual glycidyl group in the copolymer, a compound capable of forming an onium salt instead of directly reacting the onium compound,
For example, a trialkylphosphine, a tertiary amine, an alkyl sulfide or the like may be reacted in the presence of an anion source such as a halide or an organic acid. As the organic acid, formic acid, acetic acid, acrylic acid, methacrylic acid, lactic acid,
Crotonic acid, maleic acid, fumaric acid, itaconic acid and the like are used.

The onium group-containing prepolymer thus obtained preferably has an average molecular weight in the same range as in the case of the above-mentioned prepolymer. The above prepolymer and onium group-containing prepolymer can also be used in combination, but it is also possible to introduce an onium group in the former or a carboxyl group in the latter, and the water solubility is increased by introducing the onium group, and Allows development by itself.

The photosensitive resin composition of the present invention contains an inorganic powder, and typical examples thereof include non-crystalline silica, amorphous silica, high-purity crystalline silica, talc, clay, titanium oxide, calcium carbonate. , Aluminum hydroxide, alumina, barium sulfate, hydrous silicic acid, antimony trioxide, magnesium carbonate, mica powder, aluminum silicate, magnesium silicate and the like, and those used as other organic fillers. The average particle size of the inorganic powder used is 2 μm to 20 μm,
The thickness is preferably 5 μm to 15 μm, and when it is less than 2 μm, the final cured coating film of the photosensitive resin composition of the present invention is not sufficiently roughened, and the storage stability (pot life) of the solution of the photosensitive resin composition is improved. And the like, and if it is larger than 20 μm, the resolution of the coating film of the photosensitive resin composition when exposed and developed, the cured film finally obtained. The hardness and adhesion are not better than those in this range. When a plurality of inorganic powders are used, the average particle size is a value obtained by multiplying the average particle size of each inorganic powder by the weight% used, and adding it to all the used inorganic powders. Further, the mixing ratio of the inorganic powder is preferably 10% by weight or more in the photosensitive resin composition of the present invention, and if it is less than this, the final cured coating film is not sufficiently roughened and the cured coating film In terms of hardness, no better than anything else,
On the other hand, if the amount is too large, the coating film of the photosensitive resin composition of the present invention is not good in terms of resolution when exposed and developed, and adhesion of the finally obtained cured coating film. It is preferably 40% by weight or more and 40% by weight or less. It is preferable that the inorganic powder is uniformly dispersed in the photosensitive composition, and for that purpose, milling with a three-roll mill or the like is preferable. Among the inorganic powders, amorphous silica having an average particle diameter of 2 μm to 12 μm is particularly preferable, and this is preferably 5% by weight or more, more preferably 10% by weight or more in the photosensitive resin composition of the present invention. If 5 wt% or more, more preferably 10 wt% or more, of amorphous silica is blended, even if other inorganic powders are used together, the effect is obtained in the above-mentioned roughening of the cured coating film, for example. It can be significantly better than other inorganic powders alone.

The photopolymerizable reactive diluent used in the present invention is
The above prepolymer becomes a diluting solvent for the onium group-containing prepolymer, and the photo-curing of the coating film is sufficiently performed to obtain the cured coating film, and further, if necessary, heat curing in the subsequent step is added to finally obtain It is a component necessary for obtaining the acid resistance, heat resistance, chemical resistance, alkal resistance, etc. of the cured coating film obtained. Typical examples of the photopolymerizable reactive diluent include 1,4-butanediol di (meth) acrylate,
1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypentavalene neopentyl glycol di (meth) acrylate Acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth)
Acrylate, EO-modified di (meth) acrylate phosphate,
Allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (Meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipenta Photopolymerizable reactive diluents such as erythritol hexa (meth) acrylate may be mentioned, and (meth) acrole having two or more polymerizable double bonds in one molecule. Rate, that is, those preferably acrylate and / or methacrylate. The above bifunctional to hexafunctional polyfunctional photopolymerizable reactive diluents can be used alone or in combination. Further, the preferable addition amount of these photopolymerizable reactive diluents is 2.0 with respect to 100 parts by weight of the above prepolymer and onium group-containing prepolymer.
-40 parts by weight, preferably 4.0-20 parts by weight.
If the amount added is less than 2.0 parts by weight, sufficient photo-curing cannot be obtained, and even if the thermosetting component is cured after the curing, sufficient properties such as acid resistance and heat resistance of the cured coating film can be obtained. Further, if the addition amount exceeds 40 parts by weight, the tack is severe, the negative film adheres to the coating film during exposure and cannot be peeled off, and a predetermined cured coating film cannot be obtained.

Typical examples of the photopolymerization initiator contained in the photosensitive resin composition of the present invention include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, and the like. Benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone,
2,2-dimethoxy-2-phenylacetophenone,
2,2-diethoxy-2-phenylacetophenone, 2
-Hydroxy-2-methyl-1-phenylpropane-1
-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, benzophenone, 4,4'-diethylaminobenzophenone,
Dichlorobenzophenone, 2-methylanthraquinone,
2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone,
2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ethyl ester and the like can be mentioned, and these can be used alone or in combination. A suitable amount of such a photopolymerization initiator is the above-mentioned prepolymer,
0. 0 to 100 parts by weight of the onium group-containing prepolymer.
5 to 50 parts by weight, preferably 2.0 to 30 parts by weight.

The photosensitive resin composition of the present invention may contain a thermosetting component as required. The thermosetting component may be a thermosetting epoxy compound, an n-butylated melamine resin or an isobutylated compound. Melamine resin, butylated urea resin,
Examples include amino resins such as butylated melamine urea co-condensation resin and benzoguanamine-based co-condensation resin. Of these, thermosetting epoxy resins are particularly preferable. Typical examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol nolac type epoxy resin, cresol novolac type epoxy resin, N-glycidyl type epoxy resin or alicyclic epoxy resin (for example, Daicel Chemical company "EHPE-315
0 ")," YX-4000 "(epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.), hydrogenated bisphenol A type epoxy resin, triglycidyl isocyanurate, etc., and particularly" YX-4000 ", cresol novolac type epoxy resin, "TEPIC-S" [epoxy resin (Tris (2,3-epoxypropyl) isocyanurate) manufactured by Nissan Chemical Industries, Ltd.] and the like are preferable. The thermosetting component may be only the thermosetting resin, but it is preferable to use the reaction accelerator together, and the reaction accelerator may be a known epoxy such as a melamine derivative, an imidazole derivative or a phenol derivative. A curing accelerator may be used. Such a thermosetting component is preferably blended in an amount of 5 to 40 parts by weight with respect to the prepolymer and the onium group-containing prepolymer, and when the amount is less than this, the photosensitive resin composition of the present invention finally obtained. The final cured coating film may not have sufficient heat resistance, solvent resistance, and acid resistance, such as adhesion to a printed circuit board and electrical properties such as insulation resistance. Property and developability are lowered.

If desired, an organic solvent may be added to the photosensitive resin composition of the present invention, and a phthalocyanine-based or azo-based organic pigment or other coloring agent, a silicon compound or an acrylate copolymer, Leveling agents such as fluorinated surfactants, adhesion promoters such as silane coupling agents,
Thixotropic agents such as Aerosil, also hydroquinone, hydroquinone monomethyl ether, pyrogallol, tertiary butyl catechol, polymerization inhibitors such as phenothiazine, also dispersion stabilizers such as various surfactants and polymer dispersants, further antihalation agents, You may add various additives, such as a flame retardant, a defoaming agent, and an antioxidant. The photosensitive resin composition of the present invention is a photopolymerizable photosensitive resin having a carboxyl group, for example, 2 to 40 parts of a photopolymerizable reactive diluent, preferably 100 parts of the above prepolymer and an onium group-containing prepolymer. 4 to 20 parts, photopolymerization initiator 0.5 to 50 parts by weight, preferably 2 to 30 parts, inorganic powder 10 to 40 parts, and thermosetting component 5 to 40 if necessary.
Parts, and further, if necessary, an organic solvent and the above-mentioned various additives are added and mixed, and the mixture is mixed, for example, with a three-roll mill at a rate of 0.
The solid content is dispersed by, for example, mixing for 5 hours to complete a dispersion. Solids 40 to 80 percent by weight of the dispersion, the viscosity 0.5~300d · P _aS at25 ℃
Is preferred. The photosensitive resin composition thus obtained has a thickness of 10 to 100 μm (liquid film thickness) on a printed board by a screen printing method, a curtain coating method, a roll coating method, a spen coating method, a dip coating method or the like. After coating, after drying at 60 to 80 ° C. for 15 to 60 minutes and after volatilizing volatile components such as an organic solvent added as necessary, a negative film having a desired circuit pattern is adhered to the dried coating film, Ultraviolet rays are radiated from above. Then, the negative film is removed, and the coating film in the non-exposed area is removed by developing with a dilute aqueous alkaline solution as a developing solution, but the coating film in the exposed area is photocured and remains unremoved.
At this time, the diluted alkaline aqueous solution is 0.5 to 5% by weight.
An aqueous solution of sodium carbonate is generally used, but other alkaline solutions can be used. Further, when a photosensitive resin composition containing an onium group-containing prepolymer is used, it can be developed simply with water. Then 130
The solder resist film is completed by heat curing with a hot air circulation dryer or the like for 90 to 20 minutes at ˜160 ° C. It is observed that this solder resist film has no gloss in appearance and its surface is roughened, but its surface roughness is 2.5 to 7.0 μm, which is large according to the method of Examples described later. The average particle diameter of the raw material inorganic powder is 2 μm to 20 μm, and the surface roughness is preferably 2.5 μm or more, more preferably 3 μm or more and 10 μm or less. .

In the present invention, the photosensitive resin composition is used as a solder resist ink for a circuit board such as a printed circuit board, and the cured coating film can be a solder resist film, and an electronic film having the film can be used. The circuit board before mounting the component and the circuit board after mounting the electronic component having the film can be manufactured easily and have high reliability, but not limited to these, general-use paint, photosensitive adhesive, printing plate material, etc. It can be applied to a wide range of uses.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The details will be described with reference to the following examples. The function of the present invention is to obtain an average particle size of 2 to 20 μm.
Since the surface of the cured coating film made of the photosensitive resin composition containing the inorganic powder of m is roughened, the surface area of the coated surface becomes large even when the non-cleaning / low residue type flux is applied. Therefore, it is considered that the contact area of the flux becomes large, and the flux that has entered the uneven surface is difficult to be repelled and becomes droplets. Further, in this way, for example, when the flux having a low solid content is thoroughly applied to the solder resist film, for example, the jet solder of the jet solder device comes into contact with the solder resist film through the flux film and contacts the flux film. The melted solder is easily taken into the flow of the jet solder together with the flux film having a low softening point, so that a solder ball is hard to occur,
Even if it occurs, the oxide is reduced, and it becomes a ball of the molten solder metal itself, so that it easily joins the flow of the jet solder, and it is considered that the amount of the solder ball remaining can be reduced. Also, by roughening the surface,
Not only does it have a good ultraviolet ray reception efficiency and can accelerate the curing of the unexposed coating film, but the cured coating film also has a large surface area. As a result, the anchor effect is increased, and the number of points where a predetermined number of components are not soldered to the printed circuit board is reduced in combination with the above-described difficulty in forming solder poles, and the ICT pin contact property can be improved. The details are not clear, and the present invention is not limited to these ideas. Further, the coating film of the photosensitive resin composition contains a component having a carboxyl group, and can exhibit developability in a dilute alkaline solution even after exposure treatment,
When it contains an onium group, its polarity is so strong that it can be developed with just water, and if it is subsequently heat-cured, the physical properties of the cured film can be enhanced, for example, to make it suitable as a solder resist.

[0028]

Next, embodiments of the present invention will be described. First, a prepolymer as a photopolymerizable photosensitive resin having a carboxyl group was produced as follows. (A) Synthesis Example 1 (Example of using existing epoxy resin) Cresol novolac type epoxy resin (Epiclon N-665 manufactured by Dainippon Ink and Chemicals, Inc., epoxy equivalent 20)
7) 207 parts of acrylic acid and 72 parts of acrylic acid were reacted under reflux with carbitol acetate as a solvent to obtain a cresol novolac type epoxy acrylate. To this epoxy acrylate, 76 parts of hexahydrophthalic anhydride was added, and the mixture was reacted under reflux until the acid value reached a theoretical value (almost all of the added acrylic acid was esterified). A solution was obtained. Hereinafter, this is referred to as prepolymer solution RC-1.

(B) Synthesis Example 2 (Example of Synthesizing Copolymer Epoxy Resin and Utilizing It) Methyl methacrylate (MMA) and glycidyl methacrylate (GMA) were mixed at a molar ratio of 6: 4, and mixed with this. Ethyl cellosolve was added as a solvent to 40% by weight, and solution polymerization was carried out at 60 ° C. in a nitrogen gas atmosphere in the presence of azoisoztyronitrile as a catalyst to obtain a copolymer. Then, acrylic acid was reacted with 1.05 mol per 1 epoxy equivalent of this copolymer, and after the acid value became constant, 0.8 mol of tetrahydrophthalic anhydride was further reacted. As a result of analysis of the prepolymer obtained by this reaction, the weight average molecular weight was 30,000, the softening point was 60 ° C., and the acid value was 100. Hereinafter, this is referred to as prepolymer solution RC-2.

Next, an onium group-containing prepolymer as a photopolymerizable photosensitive resin containing an onium group was produced as follows. (C) Synthesis Example 3 A mixture of 100 parts by weight of methyl methacrylate (MMA), 616 parts by weight of ethyl methacrylate (EA), 234 parts by weight of glycidyl methacrylate (GMA), and 30 parts by weight of azoisobutyronitrile, and 500 parts by weight of n-butanol. The mixture was placed in a four-necked flask together with the parts, and solution polymerization was carried out at 60 ° C. under a nitrogen gas atmosphere for 10 hours to obtain a copolymer. After polymerization, 72 parts by weight of acrylic acid, 0.5 parts by weight of hydroquinone, 1 part of tetramethylammonium chloride
The reaction product was added with 60 parts by weight of acetic acid and 39 parts by weight of dimethylaminoethanol, and reacted at 70 ° C. for 4 hours. Further, this resin solution was evaporated under heating under reduced pressure to evaporate n-butanol to give an average molecular weight of 35,000.
An onium group-containing prepolymer having a softening point of 0 and a softening point of 75 ° C. was obtained. Next, 667 parts by weight of water was added to this prepolymer,
A resin solution having a solid content of 65% was obtained. Hereinafter, this is referred to as onium group-containing prepolymer solution RC-3.

(D) Synthesis Example 4 A resin solution was obtained in the same manner as in Synthesis Example 3 except that 75 parts by weight of trimethylphosphine was used instead of dimethylaminoethanol in Synthesis Example 3 above. Hereinafter, this is referred to as onium group-containing prepolymer solution RC-4.

(E) Synthetic Example 5 Synthetic Example 3 except that 62 parts by weight of methyl sulfide was used in place of dimethylaminoethanol in Synthetic Example 3 above.
A resin solution was obtained in the same manner as in. Hereinafter, this is referred to as onium group-containing prepolymer solution RC-5.

Example 1 Solvento # 150 (an aromatic solvent manufactured by Shell Chemical Co., Ltd.) was placed in a container according to the composition (expressed in parts by weight) in the column of Example 1 in Table 1, and the solution was added in the above (a). The obtained prepolymer solution RC-1, dipentaerythritol hexaacrylate, Irgacure 907 (2-methyl-1- [4- (methylthio) which is a photopolymerization initiator manufactured by Ciba-Geigy)
Phenyl] -2-monofolinopropanone-1), Kayacure DETX (2,4-diethylthioxanthone which is a photopolymerization initiator manufactured by Nippon Kayaku Co., Ltd.) are added and stirred, while continuing the stirring. Amorphous silica (average particle size 10μ
m), barium sulphate (average particle size 0.3 μm), talc (average particle size 2 μm) inorganic powder, and then Modaflow (Monsanto leveling agent) and phthalocyanine green (pigment) auxiliaries. , TEPIC-S
(Nissan Chemical Co., Ltd. thermosetting epoxy resin) and dicyandiamide (epoxy resin thermosetting accelerator) are added and stirred for 20 minutes. The obtained mixed composition was further well mixed for 30 minutes by a three-roll mill to prepare a solution of the photosensitive resin composition. The solid content of this photosensitive resin composition is 75% by weight, and the viscosity (measurement instrument Visco Tester VT-04 manufactured by Rion Co., Ltd.
(Type) was 200 d · P _{as at} 25 ° C. Next, a so-called surface-treated printed circuit board after pretreatment consisting of steps such as degreasing, soft etching, cleaning, and drying the printed circuit board on which a circuit is formed by etching the copper foil surface on the board, A solution of the photosensitive resin composition is applied by screen printing (thickness of liquid film of 35 μm),
Pre-drying (80 ° C., 20 minutes) is performed. Then, it is exposed (400 mj / cm ² ) and then developed (1%
It was immersed in an aqueous solution of sodium carbonate for 60 seconds at room temperature, dried and then post-cured (thermosetting treatment of the coating film at 150 ° C. for 30 minutes) to form a solder resist coating film. Table 2 shows the results of the test shown in the table for the test piece thus formed with the solder resist coating film on the printed circuit board according to the test method described later.

Examples 2 to 6 In the same manner as in Example 1, except that the formulations described in the respective columns of Examples 2 to 6 in Table 1 were used, the solutions of the photosensitive resin compositions of the respective examples were similarly prepared. Was manufactured. Further, in Example 1, the test pieces of Examples 2 to 6 were produced in the same manner except that the solutions of these photosensitive resin compositions were used, and the same test results are shown in Table 2.

Comparative Examples 1 to 3 In the same manner as in Example 1, except that the formulations shown in the respective columns of Comparative Examples 1 to 3 in Table 1 were used, solutions of the photosensitive resin compositions of the respective Examples were prepared in the same manner. Was manufactured. Further, in Example 1, test pieces of Comparative Examples 1 to 3 were prepared in the same manner except that the solutions of these photosensitive resin compositions were used, and the same test results are shown in Table 2.

[0036]

[Table 1]

[0037]

[Table 2]

Example 7 The prepolymer solution RC-3 obtained in the above (c) was placed in a container according to the formulation (expressed in parts by weight) in the column of Example 7 in Table 3.
Dulcure 2959 (Merck Japan 4- (2
-Hydroxyethoxy) phenyl-2 (hydroxy-2
-Propyl) ketone), A-200 (polyethylene glycol diacrylate manufactured by Shin-Nakamura Chemical Co., Ltd.), and Denacol EX.301 (triglycidyl tris (2-hydroxyethyl) isocyanurate manufactured by Nagase Kasei Co., Ltd.) are added and stirred. , While continuing the stirring, amorphous silica (average particle size 10 μm), barium sulfate (average particle size 0.3
μm), talc (average particle size 2 μm), and an inorganic powder of phthalocyanine green (pigment) are added, followed by stirring for 20 minutes. The obtained mixed composition was further well mixed for 30 minutes by a three-roll mill to prepare a solution of the photosensitive resin composition. Next, a so-called surface-treated printed circuit board after performing pretreatment consisting of steps such as degreasing, soft etching, washing, and drying the printed circuit board on which a circuit is formed by etching the copper foil surface on the board, A solution of the photosensitive resin composition is applied by screen printing (liquid film thickness of 40 to 50 μm), and then dried (80 ° C., 20 minutes) with a hot air circulation dryer.
Then, attach the negative film of the desired pattern,
UV exposure from above (exposure amount 400 mj / cm ² )
Then, development (immersion in tap water for 50 seconds) is carried out, and then post cure (150
C., 30 minutes). Thus, the solder mask was formed. The results of examining the physical properties are shown in Table 4.

Examples 8 to 15 In the same manner as in Example 7, except that the formulations shown in the respective columns of Examples 8 to 15 in Table 3 were used, solutions of the photosensitive resin compositions of the respective examples were obtained. Was manufactured. Also,
In Example 7, the test pieces of Examples 8 to 15 were produced in the same manner except that the solutions of these photosensitive resin compositions were used, and the results of the same test are shown in Table 4.

[0040]

[Table 3]

[0041]

[Table 4]

Comparative Examples 1 to 3 In the same manner as in Example 7, except that the formulations shown in the respective columns of Comparative Examples 4 to 6 in Table 5 were used, solutions of the photosensitive resin compositions of the respective Examples were prepared. Was manufactured. Further, in Example 7, test pieces of Comparative Examples 4 to 6 were prepared in the same manner except that the solutions of these photosensitive resin compositions were used, and the results of the same test are shown in Table 6.

[0043]

[Table 5]

[0044]

[Table 6]

The test method is as follows. (A) Solder ball test Using a jet type automatic soldering device SC-30-55 (manufactured by Tamura Corporation), flux was applied to the circuit surface side of the test piece, and the surface temperature on the circuit surface side was set to 90 ° C. After preheating, the circuit surface side on which the flux film was formed was immersed in jet solder at 250 ° C. for 4 seconds, then moved to the air and cooled to perform soldering treatment. The flux is an ultra low residue type ULF-210R manufactured by Tamura Kaken Co., Ltd.
It was used. The number of solder balls having a solder ball diameter of 10 μm or more was counted while visually observing the number of solder balls on the circuit surface side subjected to the soldering treatment with a 30 × magnifying glass. The size of the test piece is 150 mm x 100 mm x 1.6 m
m, and the number of solder balls in the area of 150 mm × 100 mm on the circuit side surface was used as the measured value.

(B) Solder heat resistance test According to the test method of JIS C 6481, the cured coating film of the above test piece was dipped in a solder bath at 260 ° C. for 30 seconds, and a peeling test with cellophane tape was defined as one cycle. The state of the coating film after repeating three times was evaluated in four levels as follows. ⊚: No change was observed in the coating film after repeating 3 cycles ◯: Slight change was observed in the coating film after repeating 3 cycles Δ: Change was observed in the coating film after repeating 2 cycles ×: Peeling is recognized in the coating film after repeating 1 cycle

(C) Chemical resistance test The above test piece was immersed in 10% hydrochloric acid for 30 minutes, and the state of the coating film was visually observed and evaluated in four grades as follows. ⊚: No change observed ○: Slight change observed Δ: Remarkably changed ×: Swelled and peeled coating film

(D) Solvent resistance test The state of the coating film after immersing the above test piece in methylene chloride for 30 minutes was observed with the naked eye, and evaluated in four levels as follows. ⊚: No change is observed ○: Only slight change is observed Δ: Remarkable change is observed ×: Coating film is swollen and peeled off

(E) Electrical characteristics (insulation resistance and discoloration) A comb-shaped electrode of IPC-SM-840BB-25 test coupon is placed on the coating film of the above-mentioned test piece, and the temperature is 60 ° C. and 90% RH.
A direct current of 100 V was applied in the constant temperature and humidity chamber, and the state of insulation resistance and discoloration after 500 hours was evaluated according to the following criteria. ◎: No discoloration ○: Light discoloration △: Discoloration ×: Black charring

(F) Sensitivity test The amount of ultraviolet light having a wavelength of 365 nm that passed through a Kodak step tablet was measured using an integrating photometer manufactured by Oak Manufacturing Co., Ltd. so that the value was 400 mJ / cm ² , The liquid film (35 μm) of the solution of the photosensitive resin composition coated on the printed circuit board is irradiated with ultraviolet rays, and the coating film after the irradiation is diluted with a dilute alkaline aqueous solution (1 wt% sodium carbonate aqueous solution) at 2.0 kg / cm. After spraying at a spray pressure of ² for 60 seconds, the area of the exposed portion that was not removed was measured.

(G) Surface Roughness Test The surface roughness of the cured coating film of the above test piece was measured by Surfcom 570A, a surface roughness measuring instrument manufactured by Tokyo Seimitsu Co., Ltd.

(H) Developability Test (Development with Dilute Alkaline Water) A test piece was prepared by irradiating 400 mj / cm ² of ultraviolet light having a peak wavelength of 365 nm through an artwork film using an Oak meter photometer. 6% normal temperature in 1% sodium carbonate solution
The state in which the unexposed portion was removed after the immersion for 0 seconds was visually determined, and evaluated in four levels as follows. (Development with water) Through the artwork film 365
A test piece was prepared by irradiating 400 mj / cm ² of ultraviolet light having a peak wavelength of nm with a photometer manufactured by Oak Manufacturing Co., Ltd., and used as a test piece at a spray pressure of 2.0 Kg / cm ² with tap water.
The state in which the unexposed portion was removed after the development for 0 seconds was visually determined, and evaluated in four stages as follows. ⊚: Completely developed ○: Surface has a thin undeveloped portion Δ: Overall development residue or partial cracking or swelling of coating film ×: Almost no development or coating film Cracked throughout,
Swelling is seen

(I) Adhesion According to the test method of JIS D.0202, a cross-cut is put on a test piece in a grid pattern, and then the state of peeling after a peeling test with cellophane tape is visually determined, and the following criteria are used. evaluated. ⊚: No change was observed at 100/100 ◯: Cross-cut portion was slightly peeled off at 100/100 Δ: 50/100 to 90/100 ×: 0/100 to 50/100

(J) Pencil Hardness Evaluation was performed according to the test method of JIS K-5400.

(K) Adhesive Adhesion Test (For Temporary Fixing of Surface Mounted Products) For fixing surface mount parts (SMD), an adhesive was supplied to two spots of a test piece by a dispenser (amount of adhesive per spot). 1 mg), when the SMD is mounted and fixed thereon, the bonding strength of the SMD (load for pulling and peeling) [Kg / (1 mg × 2 spots)]
Is measured. (For strap wire fixing) A bond strength (load for peeling the strap wire) (g / φ5) when a strap wire having a radius of 2.5 mm is fixed to a test piece with an adhesive is measured.

(L) Solder joint quality of the three-dimensional automatic visual inspection machine Judgment of false alarm rate Optical three-dimensional automatic visual inspection to judge whether the soldering portion of the component is acceptable or not. Even if the solder resist film around the joint has gloss, light reflection may impair the joint judgment. Calculate the false alarm rate.

(M) ICT pin contact test Pin contact test with the test piece in the inspection by the in-circuit tester. When the solder resist film has a rough surface, the flux residue adheres uniformly, the pin contact (contact property) is not disturbed, and conduction (contact) defects due to the flux residue are reduced. The defect rate (%) per 100 sheets is displayed.

From the above results, the cured coating film finally obtained by using the photosensitive resin composition of the example of the present invention can be 27 or less, more preferably 5 or less in the solder ball test. On the other hand, it is 50 or more in the comparative example,
The surface roughness of the example is 2.5 or more,
It is 2.5 to 7, and it can be seen that the solder ball test result can be reduced to 5 or less in the case of 3 or more of the examples, whereas it is 2 or less in the comparative example. From this, it is possible to reduce the number of solder balls counted by the solder ball test to 27 or less at the surface roughness of 2.5 to 7, and to reduce the solder ball count to 5 or less by the solder ball test at the surface roughness of 3 to 7. By roughening the surface, it is possible to reduce eye strain during inspection. Further, in flow soldering, it is possible to bring about an increase in physical resistance and an increase in chemical resistance (prevention of external stress, flux, chipping due to solvent, peeling off) with an increase in edge coverage, and also by improving flux affinity. Attachability and appearance, reliability,
Workability can be improved.

[0059]

According to the present invention, it is possible to form a cured coating film such as a solder resist film which does not cause leakage of coating of a liquid such as non-cleaning / low residue type flux and has good flux affinity. For example, even when using a coating composition having a low solid content such as a non-cleaning / low residue type flux, a cured coating film such as a solder resist film in which molten metal balls such as solder balls are unlikely to occur during soldering can be formed, Also,
For example, it is possible to provide a photosensitive resin composition capable of forming a solder resist film and the like with high resolution and high accuracy, a cured coating film thereof, and a circuit board using the cured coating film. Further, it is possible to form, for example, a solder resist film having excellent heat resistance, adhesion to a coated surface, chemical resistance, solvent resistance, electrical characteristics, and mechanical characteristics, and to develop with a dilute alkaline solution. It is possible to further develop it and develop it only with water, so that it is possible to form, for example, a solder resist film, etc., and it is hard to cause environmental pollution, and a photosensitive resin composition with less risk of fire. A cured coating film and a circuit board using the cured coating film can be provided. In addition, the adhesive strength of the adhesive for temporarily fixing parts and members such as surface mount parts and strap lines can be improved, the false alarm rate of the three-dimensional automatic visual inspection machine can be reduced, and the ICT pin contactability can be improved. It is possible to provide a photosensitive resin composition capable of obtaining a cured coating film such as a solder resist film, a cured coating film thereof, and a circuit board using the cured coating film. Also,
It is possible to provide a circuit board before mounting an electronic component, which can improve soldering productivity and reliability, and a circuit board after mounting an electronic component, which does not impair the reliability of the circuit function and is high in productivity and inexpensive. it can. Further, the photosensitive resin composition of the present invention can also be used as a paint in other fields, adhesives, printing plate materials, etc., to improve the performance by imparting the above-mentioned various properties to the cured coating film, The function of an object using the coating film can be improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuji Ishikawa 4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Tetsuo Kurokawa 4-1-1 Ueodachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture 1 Within Fujitsu Limited (72) Inventor Koichi Ishida 4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Fujitsu Limited

Claims (19)

[Claims] 1. A photosensitive material containing a photopolymerizable photosensitive resin having at least one of a carboxyl group and an onium-containing group, a photopolymerizable reactive diluent, a photopolymerization initiator, and an inorganic powder having an average particle size of 2 μm to 20 μm. Resin composition. 2. The photosensitive resin composition according to claim 1, which contains a thermosetting component. 3. The photosensitive resin composition according to claim 1, wherein the inorganic powder is non-crystalline silica and is contained in an amount of at least 10% by weight. 4. A photopolymerizable photosensitive resin having a carboxyl group is a reaction product of an epoxy resin and 0.3 to 1.2 mol of α, β unsaturated carboxylic acid per epoxy equivalent of the epoxy resin. A prepolymer which is a reaction product of an epoxy resin / α, β unsaturated carboxylic acid ester and 0.2 to 1.0 mol of a polybasic acid and / or an anhydride thereof per epoxy equivalent of the epoxy resin. Claim 1,
The photosensitive resin composition according to 2 or 3. 5. The epoxy resin is an epoxy resin having at least two terminal epoxy groups, or a monomer represented by the following general formula [Chemical formula 1] and a monomer represented by the following general formula [Chemical formula 2] are used. The photosensitive resin composition according to claim 4, which is a copolymer of a plurality of contained monomers. Embedded image (In the formula, R ₁ is a hydrogen atom or a methyl group, R ₂ is a carbon atom 1
~ 6 aliphatic hydrocarbon groups are shown. ) (In the formula, R ₃ is a hydrogen atom or a methyl group, R ₄ is a carbon atom 1
~ 12 aliphatic hydrocarbon groups or aromatic hydrocarbon groups are shown. ) 6. The photopolymerizable photosensitive resin containing an onium group is selected from at least one monomer selected from alkyl acrylate and alkyl methacrylate, and an epoxy group-containing acrylate and an epoxy group-containing methacrylate. 3. An onium group-containing prepolymer in which an acryloyl group or methacryloyl group is introduced as a part of the epoxy group of the copolymer with at least one epoxy group-containing monomer selected and an onium group is introduced as the balance. 2. The photosensitive resin composition according to 2 or 3. 7. At least one monomer selected from alkyl acrylates and alkyl methacrylates, and at least one epoxy group-containing unit selected from epoxy group-containing acrylates and epoxy-containing methacrylates. The photosensitive resin composition according to claim 6, wherein the molar ratio with the body is 40:60 to 60:20. 8. Acryloyl group or methacryloyl group is contained in an amount of 80 to 2 in 20 to 80 mol% of epoxy groups in the copolymer.
The photosensitive resin composition according to claim 6, wherein the onium-containing group is introduced in 0 mol%. 9. The average molecular weight of the prepolymer is 20,000.
The photosensitive resin composition according to claim 6, 7 or 8, which is 0 to 70,000. 10. The photosensitive resin composition according to claim 1, wherein the photopolymerizable reactive diluent is an acrylate and / or a methacrylate having two or more polymerizable double bonds in one molecule. . 11. The photosensitive resin composition according to claim 2, wherein the thermosetting component contains a thermosetting epoxy compound. 12. The photopolymerization initiator of 0.5 to 50 parts by weight and the photopolymerizable reactive diluent of 2 to 40 parts by weight are contained per 100 parts by weight of the onium group-containing prepolymer. The photosensitive resin composition according to item 1. 13. The photosensitive resin composition according to claim 1, which is a solder resist ink for circuit boards. 14. A cured coating film of a photosensitive resin composition, which is obtained by photo-curing and heat-curing the coating film of the photosensitive composition according to claim 1. 15. The cured coating film according to claim 14, which has a surface roughness of 2.5 to 10 μm. 16. A circuit board comprising a coating film of the photosensitive composition according to claim 13, which comprises a photo-cured or photo-cured and heat-cured solder resist film. 17. The surface roughness of the solder resist film is 2.
The circuit board according to claim 16, which has a thickness of 5 to 10 μm. 18. The circuit board according to claim 16, which is before mounting electronic components. 19. The circuit board according to claim 16, which has been mounted with electronic components.