JPS63157143A - Solder resist pattern forming method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for forming a solder resist pattern used for a printed wiring board.

(Prior art) In recent years, the wiring density of printed wiring boards has rapidly increased, and instead of solder resist, which forms images using the conventional screen printing method, images are formed using photolithography, which has better resolution. Liquid solder resists have been developed. - As such a solder resist, a solder resist whose main component is an epoxy resin having a photosensitive group or a photocurable resin obtained by reacting an epoxy resin with a compound having a photosensitive group is disclosed in, for example, JP-A-58-626.
No. 36, JP-A-60-208377, JP-A-81-2
It is disclosed in No. 72.

However, these solder resists are most preferable from the viewpoint of ensuring safety in the manufacturing process of printed wiring boards and ensuring a sanitary environment, and are non-flammable and relatively less harmful.
When 1.1.1-tricloethane was used in a developer, there was a problem that the solubility was low and the developability was extremely poor. However, these solder resists are prepared using flammable organic solvents or alcoholic solvents in 1,1°1-trichloroethane.
It must be developed using a mixed solvent containing an ether solvent or the like. However, as mentioned above, the use of flammable solvents is not preferable in terms of ensuring safety in the manufacturing process. Further, in a mixed solvent system, when the developer is regenerated by distillation, the solution composition tends to change, and when used as a developer again, there is a problem that it tends to cause poor development.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned conventional problems. It is an object of the present invention to provide a method for forming a solder resist pattern in which good development can be achieved using a liquid and the developer can be recycled.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides the following features: (a) 0.4 to 0.6 equivalents of acrylic acid and/or
or a partially acrylated and/or methacrylated epoxy resin to which methacrylic acid has been added, (b) at least 3
A solder resist containing a photopolymerizable monomer having 2 acryloyl groups and soluble in 1,1,1-trichloroethane, (c) a photopolymerization initiator, and (d) a thermosetting agent is applied to the base material. This is a method of forming a solder resist pattern, which comprises selectively irradiating the solder resist film with light and then developing it with a developer comprising 1°1,1-trichloroethane and a surfactant.

The partially acrylated and/or methacrylated epoxy resin (a) above is obtained by subjecting a cresol novolac type epoxy resin to an addition reaction with acrylic acid, methacrylic acid, or a mixture thereof. The epoxy resin used here is limited to the cresol novolak type, and other types of epoxy resins, such as bisphenol A type, bisphenol F type, diglycidyl ether type of diol,
Even if epoxy resins such as hydrogenated bisphenol A type or diglyresyl ester type of dicarboxylic acid are used, solder resists containing partially acrylated and/or methacrylated epoxy resins have poor soldering heat resistance of the cured film. Undesirable. Furthermore, although the phenol novolac type epoxy resin has a similar structure to the cresol novolac type epoxy resin and has excellent heat resistance, it cannot be used because its solubility in 1,1,1-trichloroethane is extremely low. The addition reaction method may be carried out according to a conventional method, but in the reaction, acrylic acid and/or methacrylic acid is used in an amount of 0.4 to 0.8 equivalents, more preferably 0.4 to 0.8 equivalents per 1 epoxy equivalent of the cresol novolac type epoxy resin. 0
．． It is necessary to carry out the addition reaction at 45 to 0.55 equivalents. The reason for this is that the equivalent of acrylic acid used in the reaction is 0.
If it is less than 4, the photocurability of the solder resist will decrease. On the other hand, if the equivalent of acrylic acid etc. exceeds 0.6, 1
．． 1. The solubility in 1-trichloroethane is extremely reduced, leading to inability to develop.

having at least three acryloyl groups of the above (b),
In addition, the photopolymerizable monomer soluble in 1,1,1-trichloroethane imparts excellent sensitivity to the solder resist during exposure, and is highly resistant to developing solutions containing 1°1,1-trichloroethane as a main component. Required to improve developability. Furthermore, excellent heat resistance, surface hardness, solvent resistance, etc. can be added to the cured solder resist film. Such (b'1 component includes, for example, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate,
Tetramethylolmethanetetraacrylate, Tris(
Examples include reaction products of trimers of acryloyloxyethyl isocyanurate and hexamethylene diisocyanate and acrylic acid esters having one hydroxyl group such as 2-hydroxyethyl acrylate, glycerin diacrylate, and pentaerythritol triacrylate. be able to.

The photopolymerization initiator (c) above can be transformed into the photopolymerization initiator (a) by light irradiation.
The photopolymerization initiator is not particularly limited as long as it is generally known as an acrylate photopolymerization initiator. Specifically, biacetyl, benzophenone, benzyl, benzoin isobutyl ether, benzyl dimethyl ketal, (1-hydroxycyclohexyl) phenyl ketone,
2-hydroxy-2methylpropiophenone, diethylthioxanthone, ethyl anthraquinone, bis(diethylamino)benzophenone, etc., and these compounds and ethyl (N,N-dimethylamino)benzoate, benzyldimethylamine, triethanolamine, N, Examples include composite photopolymerization initiators with amines such as N-dimethylethanolamine.

The thermosetting agent (d) above is a component that imparts excellent heat resistance, electrical properties, moisture resistance, chemical resistance, etc. to the resin by crosslinking the epoxy groups in the component (a) by heating. be. As such a thermosetting agent, amines, imidazole derivatives, etc., which are generally known as epoxy resin curing agents, can be used. Specifically, diethylenetriamine, triethylenetetraamine, diethylaminoprobylamine, benzyldimethylamine, tris(dimethylaminomethyl)phenol, diaminodiphenylmethane, xylylenediamine, dicyandiamide, 2-methylimidazole, 2-ethyl-4-methyl Examples include imidazole, 1-benzyl-2-methylimidazole, and the like.

The blending ratio of components (a) to (d) constituting the solder resist is as follows: (If the total of components (a) to (1) is 100 parts by weight, the blending ratio of component (a) is 40 to 90 parts by weight. , preferably 50 to 80 parts by weight, the blending ratio of component (b) to 3 to 50 parts by weight, preferably 5 to 40 parts by weight, (c)
The blending ratio of the components is 2 to 15 parts by weight, preferably 4 to 10 parts by weight.
parts by weight, the blending ratio of component (d) is 0.5 to 10 parts by weight,
The amount is preferably 1 to 7 parts by weight. Said (
If the blending ratio of component a) is less than 40 parts by weight, heat resistance may be poor, and if it exceeds 90 parts by weight, photocurability and developability may be poor. When the proportion of the component (b) is less than 3 parts by weight, photocurability and developability may be poor, and when it exceeds 50 parts by weight, heat resistance and adhesion to the substrate may be poor. If the blending ratio of <C) component is less than 2 parts by weight, the photocurability may be poor, and if it exceeds 15 parts by weight, the heat resistance, moisture resistance, and electrical properties of the solder resist may be poor. (d) The blending ratio of the component is 0.5 ti
If it is less than 1 part f, the thermosetting properties may be poor, and if it exceeds 10 parts by weight, the heat resistance, moisture resistance, and electrical properties may be poor.

In addition to the above-mentioned components (a) to (d), the solder resist may optionally include a flame retardant agent, an inorganic filler, a dye, a pigment, an antifoaming agent, and a leveling agent. , a polymerization inhibitor, a solvent, an adhesion imparting agent, etc. can be blended. The blending ratio is 50 parts by weight or less, preferably 40 parts by weight or less, when the total of the components (a) to (d) is 100 parts by weight. If the blending ratio of these additives exceeds 50 parts by weight, it is not preferable because the curability of the solder resist will be poor.

The light for selectively irradiating and photocuring the solder resist film usually has a wavelength of 200 to 500 nm.
ls preferably used is one with a wavelength of 300 to 450 nm.

The above-mentioned developer has a composition mainly composed of 1.1.1-trichloroethane, to which is added a small amount of a surfactant that effectively enhances the developing power of the 1,1.1-trichloroethane. . A developing method using a developer having such a composition can develop more effectively than the conventional method in which the 1゜1.1-trichloroethane is mixed with other alcohol-based solvents, ether-based solvents, etc. to increase the developing power. You can increase your power. Examples of such surfactants include nonylphenol ethoxylate, octylphenol ethoxylate, vine and tanstearyl ester, polyoxyethylene sorbitan stearyl ester, sorbitan oleyl ester, polyoxyethylene sorbitan oleyl ester, sodium alkylbenzene sulfonate, pensalkonium chloride, Examples include, but are not limited to, polyoxyethylene alkylaryl ether, cetylpyridinium chloride, and phosphoric acid ester of polyoxyethylene monoaryl ether. In addition, the blending ratio of surfactant is 1,1゜1-trichloroethane 1
It is desirable to use 0.5 parts by weight or more per 00 parts by weight. The reason for this is that if the amount of the surfactant is less than 0.5 parts by weight, the effect of improving the developing power may not be sufficiently achieved. Note that the upper limit of the amount of surfactant blended is preferably 5 parts by weight from an economical point of view. A more preferred amount of surfactant is in the range of 1 to 3 parts by weight.

(Function) The present invention uses a solder resist containing the above-mentioned components (a) to (d) and a developer containing the above-mentioned 1, i, i-trichloroethane as a main component and a surfactant mixed therein. 1.1.1 The solder resist after selective light irradiation (exposure) is non-flammable and has relatively low toxicity.
- It can be developed well with the developer containing trichloroethane as a main component, and a highly accurate solder resist pattern that is faithful to the mask etc. during exposure can be formed.

In addition, by distilling the developer consisting of 1,1,1-trichloroethane and a surfactant, only 1,1,1-trichloroethane is recovered as a fraction, and the surfactant and the solder dissolved by the development are recovered. It can be almost completely separated from the resist components. For this reason, the recovered 1, 1.
1-Trichloroethane can be used again as a developer by adding a surfactant in a predetermined proportion. Therefore, in the method of the present invention, 1,1,1-trichloroethane can be used repeatedly by only slightly replenishing the unrecovered amount in the separation operation, which can greatly contribute to reducing the manufacturing cost of printed wiring boards.

Furthermore, if the solder resist pattern formed by the above development is heated, or subjected to heating and light irradiation, the curing reaction will further proceed and the heat resistance, electrical properties, etc. required of the solder resist pattern can be improved. The heating conditions at this time are usually 100 to 170°C, preferably 120 to 170°C.
The temperature may be 150°C.

(Examples of the Invention) The present invention will be explained in more detail by giving Examples and Comparative Examples below. In addition, all "parts" in Examples and Comparative Examples represent "parts by weight."

Example 1 After heating 1000 parts of a cresol novolac type epoxy resin (product name: Epiclon N-673, manufactured by Dainippon Ink Co., Ltd., product name: Epiclon N-673) with 4.7 equivalents of bad epoxy groups and 100 parts of toluene to 120°C and dissolving them. , 1 part of p-methoxyphenol, and 5 parts of triphenylphosphine were added and dissolved. Subsequently, 1136 parts (2.3 equivalents) of acrylic acid were added while maintaining the temperature at 100°C. Thereafter, the mixture was reacted at the above temperature for 3 hours to obtain 5096 acrylated epoxy resin. Subsequently, 109 parts of this 50% acrylated epoxy resin, 10 parts of tris(acryloyloxyethyl)isocyanurate, 6 parts of benzyl dimethyl ketal,
2 parts dicyanamide, 18 parts dimethylformamide, 10 parts solvent naphtha, 1 part phthalocyanine green,
Mix 0.5 parts of silicone oil and 30 parts of talc,
The mixture was further kneaded with a roll to prepare a solder resist.

Next, the solder resist was applied to a thickness of 35 μm over the entire surface of the copper through-hole printed wiring board by screen printing. Subsequently, this coating film was dried at 80° C. for 30 minutes to form a solder resist film, and then it was selectively irradiated with ultraviolet rays at an illumination intensity of 10m W/aA for 100 seconds using a high-pressure mercury lamp through a negative mask.

Next, nonylphenol ethoxylate (Asahi Denka Kogyo Co., Ltd.) was added to 100 parts of 1,1,1-trichloroethane.
The solder resist film was developed by spraying for 1 minute using a developer containing 2 parts of Adecatol NP-660. In this developing step, the solder resist film could be developed well, and no undeveloped resist was observed.

Furthermore, when the film was cured by heating at 140° C. for 1 hour after the development process, a highly accurate cured solder resist pattern faithful to the negative mask was formed.

Example 2 First, 1000 parts of a cresol novolac type epoxy resin having 4.7 equivalents of epoxy groups (Dainippon Ink Co., Ltd., cleavage product name: Epiclon N-873) and 2 parts of solvent naphtha.
00 parts were heated to 120°C and dissolved, and 2 parts of p-methoxyphenol, 7 parts of triphenylphosphine and 152 parts of acrylic acid (2.11 equivalents) were added.
The reaction was carried out at ℃ for 3 hours to obtain a 45% acrylated epoxy resin. Continuing, this 45% acrylated epoxy resin 1
17 parts, tetramethylolmethanetetraacrylate 1
0 parts, 4 parts of 2,4-diethyloxanthone, ethyl (p
-dimethylamino)benzoate 4 parts, 2-ethyl-4
- 3 parts of methylimidazole, 16 parts of solvent naphtha,
30 parts of butyl cellosolve, 1 part of phthalocyanine green, 065 parts of silicone oil, and 25 parts of talc were mixed and further kneaded with a roll to prepare a solder resist.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, and exposed. Subsequently, the solder resist film was developed by spraying for 1 minute using a developer prepared by adding 2 parts of sodium dodecylbenzenesulfonate to 100 parts of 1,1.1-) dichloroethane.

In this developing step, the solder resist film could be developed well, and no undeveloped resist was observed. Furthermore, when the resist was heated and cured in the same manner as in Example 1 after the development step, a highly accurate cured solder resist pattern faithful to the negative mask was formed.

Example 3 Partially acrylated epoxy resin 109 obtained in Example 1
part, acrylic resin 5 which is a reaction product of hexamethylene diisocyanate trimer and glycerin diacrylate
7 parts of benzyl dimethyl ketal, 3 parts of dicyandiamide, 17 parts of dimethylformamide, 10 parts of butyl cellosolve, 1 part of phthalocyanine green, 0.5 parts of silicone oil, 10 parts of silica and 20 parts of talc,
Further, the mixture was kneaded with a roll to prepare a solder resist.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, and exposed. Subsequently, the solder resist film was developed by spraying for 1 minute using a developer prepared by adding 3 parts of polyoxyethylene sorbitan oleyl ester to 100 parts of 1,1,1-trichloroethane. In this developing step, the solder resist film could be developed well, and no undeveloped resist was observed. Furthermore, when the resist was heated and cured in the same manner as in Example 1 after the development step, a highly accurate cured solder resist pattern faithful to the negative mask was formed.

Example 4 Partially acrylated epoxy resin 117 obtained in Example 2
parts, dipentaerythritol hexaacrylate 10 parts, benzyl dimethyl ketal 8 parts, 2-ethyl-4-methylimidazole 3 parts, solvent naphtha 16 parts, ethoxyethyl acetate 30 parts, phthalocyanine green 1 part, silicone oil 0.5 parts , 10 parts of hydrated alumina, and 40 parts of talc were mixed and further kneaded with a roll to prepare a solder resist.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, and exposed. Subsequently, the solder resist film was developed by spraying for 1 minute using a developer prepared by adding 2 parts of benzalkonium chloride to 100 parts of 1,1,1-trichloroethane.

In this developing step, the solder resist film could be developed well, and no undeveloped resist was observed. Furthermore, when the resist was heated and cured in the same manner as in Example 1 after the development step, a highly accurate cured solder resist pattern faithful to the negative mask was formed.

Comparative Example 1 The solder resist obtained in Example 1 was
The process was carried out in the same manner as in Example 1, except that development was performed only with trichloroethane. The appearance after development was extremely thin, with a slight amount of resist remaining after development.

Comparative Example 2 First, 1000 parts of a cresol novolak type epoxy resin (manufactured by Dainippon Ink Co., Ltd., part name: Ebicuron N-873) having 4.7 equivalents of epoxy groups and 100 parts of toluene were heated to 120°C and dissolved. Further, 2 parts of p-methoxyphenol, 5 parts of triphenylphosphine, and 238 parts (3.3 equivalents) of acrylic acid were added, and the mixture was reacted at 100°C for 4 hours to obtain 7026 acrylated epoxy resin. Subsequently, 109 parts of this 70% acrylated epoxy resin, 10 parts of tris(acryloyloxyethyl) isocyanurate, 6 parts of benzyl dimethyl ketal, 2 parts of dicyanamide, 18 parts of dimethylformamide, 10 parts of solvent naphtha, 1 part of phthalocyanine green, and silicone oil. 0.5 part and 30 parts of talc were mixed and further kneaded with a roll to prepare a solder resist.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, exposed, and further developed. In this development, the unexposed areas were insufficiently developed and a thin film remained.

Comparative Example 3 First, 1000 parts of Talesol novolac type epoxy resin (Dainippon Ink Co., Ltd., splitting product name: Ebicuron N-873) having 4.7 equivalents of epoxy groups and 200 parts of solvent naphtha were heated to 120°C and dissolved. After adding 2 parts of p-methoxyphenol, 7 parts of triphenylphosphine and 102 parts (1,42 equivalents) of acrylic acid,
The reaction was carried out at 0° C. for 2 hours to obtain a 30% acrylated epoxy resin. Subsequently, 117 parts of this 30% acrylated epoxy resin, 10 parts of tetramethylolmethanetetraacrylate, 4 parts of 2,4-diethyloxanthone, and ethyl (
p-dimethylamino)benzoate 4 parts, 2-ethyl-
3 parts of 4-methylimidazole, 16 parts of solvent naphtha, 30 parts of butyl cellosolve, 1 part of phthalocyanine green
1 part, 0.5 parts of silicone oil, and 25 parts of talc were mixed and further kneaded with a roll to prepare a solder resist.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, exposed, and further developed. When the film was heated and cured after such development, swelling was observed at the side of the circuit at the time of curing.

Comparative Example 4 A solder resist similar to Example 1 was prepared except that tris(acryloyloxyethyl)isocyanurate among the solder resist components of Example 1 was not used.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, exposed, and further developed. When the film was heated and cured after such development, swelling was observed at the side of the circuit at the time of curing.

Comparative Example 5 A solder resist similar to Example 2 was prepared except that among the solder resist components of Example 2, tripropylene glycol diacrylate was used instead of tetramethylolmethanetetraacrylate.

Next, the solder resist was applied to a copper through-hole printed wiring board in the same manner as in Example 1, dried, exposed, and further developed. When the film was heated and cured after this development, a highly accurate cured solder resist pattern faithful to the negative mask was formed.

Therefore, regarding the printed wiring boards on which the solder resist patterns of Examples 1 to 4 and Comparative Examples 1 to 5 were formed,
Photocurability, solder heat resistance and developability tests were conducted.

The results are shown in the table below.

Note that photocurability, solder heat resistance, and developability were tested and evaluated by the methods described below.

(2) Photocurability: The state of the coating film after development and heat curing was evaluated. In the table shown as the judgment criteria, ○ means no abnormality, and × means the occurrence of swelling.

(2) Solder heat resistance: The state of the coating film was evaluated after it was repeatedly immersed in a 260° C. solder bath for 20 seconds three times.

In the table shown as the judgment criteria, ○ means that there is no abnormality, and × means that swelling, peeling, and peeling occur in the peeling test with adhesive tape.

(2) Developability: A printed circuit board was placed in contact with the back solder surface on a solder bath at 245° C. and allowed to stand for 5 seconds, and the soldered state of the copper surface of the contact surface and the through-hole portion was evaluated. As a criterion, O in the table means that the entire surface and through-hole portions are soldered, and × means that there is a partial soldering defect.

table *) Not carried out because a good coating film could not be obtained.

As is clear from the table above, in Examples 1 to 4 in which solder resists and developers with specific compositions were used, the solder resist patterns formed on copper through-hole printed wiring boards had photocurability, heat resistance, and developability. It can be seen that it shows excellent characteristics in sex.

[Effects of the Invention] As detailed above, according to the present invention, by using a solder resist with a specific composition and a developer containing 1,1,1-trichloroethane as the main component and adding a surfactant, non-flammable Good development can be achieved using the developer, which has relatively low toxicity and toxicity, and the developer can be recycled. Furthermore, it is possible to form a solder resist pattern with excellent photocurability and heat resistance, and as a result, it is possible to form a solder resist pattern with excellent photocurability and heat resistance. It can be effectively applied to manufacturing and has remarkable effects such as contributing to reducing manufacturing costs of the substrate.

Claims (1)

[Scope of Claims] (a) 0.4 to 0.6 equivalent of acrylic acid and/or
or a partially acrylated and/or methacrylated epoxy resin to which methacrylic acid is attached, (b) having at least 3 acryloyl groups, and 1
, a photopolymerizable monomer soluble in 1,1-trichloroethane, (c) a photopolymerization initiator, and (d) a thermosetting agent. 1. A method for forming a solder resist pattern, which comprises irradiating the solder resist pattern and then developing the solder resist pattern with a developer comprising 1,1,1-trichloroethane and a surfactant.