JPH0216566A - Photosensitive resin composition - Google Patents

Abstract

PURPOSE:To provide heat resistance and chemical resistance to the above compsn. and to improve the adhesive property to a substrate by incorporating specific polyurethane (meth)acrylate, linear high-polymer compd. and photopolymn. initiator which forms free radicals by receiving the irradiation of light and at least either of tetrazole and the deriv. thereof. CONSTITUTION:The polyvalent arom. isocyanate expressed by formula I and the polyurethane (meth)acrylate which is obtd. by bringing the (meth)acrylate monoester of dihydric alcohol into reaction and has >=2 (meth)acryloyl groups and >=2 urethane bonds in the molecule are incorporated as essential components into the compsn. The compsn. contains the linear high-polymer compd., the photopolymn. initiator which forms free radical by receiving the irradiation of light and at least either of tetrazole and the deriv. thereof. In formula, (k) denotes 1 or 2, (i) denotes 1 or 2; (m) denotes 1 or 2; P1 - (k-k) and Q1 - (4-1) and R1 - (5-m) denote a hydrogen atom or methyl group; (n) denotes 0-20 integer. The high crosslinking degree is attained and the wet heat resistance are improved in this way; in addition, the adhesive property of a photoresist to a metallic sheet is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a photosensitive resin composition. More specifically, the present invention relates to a photosensitive resin material that has excellent properties that can be used in the production of printed wiring boards and can be used to form solder masks and protective films for chemical plating.

[Conventional technology]

The solder mask limits the soldering area when soldering is performed. Protect copper conductors from S corrosion. It is used for purposes such as maintaining electrical insulation between conductors. In the past, thermosetting resins such as epoxy resins were screen printed, but as wiring patterns became finer, screen printing methods were no longer able to achieve satisfactory accuracy. In addition, with the increase in wiring density, the reliability of the insulation between conductors is becoming increasingly required, and the requirements for these are also becoming stricter. . In the screen printing method, it is difficult to form a thick film in one coating, and it is also difficult to uniformly coat the substrate. In this case, these problems can be solved by repeating printing two or three times, but the accuracy of printing decreases as the number of times increases, and the process becomes more complicated. For these reasons, it is desired to develop a photosensitive resin composition for forming a solder mask.

On the other hand, there are photoresists called photosensitive dry films used to form conductor patterns for printed wiring, but these have sufficient heat resistance and chemical resistance when used to form protective films for solder masks and chemical plating. However, there is a problem in that it cannot be used for these purposes.

In order to solve these problems, we have proposed a photosensitive element that can be used for forming a solder mask, such as the method described in Japanese Patent Application Laid-open No. 53-56018 regarding a photosensitive element that has flame retardancy, and has improved cold and thermal shock resistance. Special Publication on Improved Composition in 1973
The methods described in Japanese Patent Publication No. 9-23723 and Japanese Patent Publication No. 60-1885 have been proposed.

Furthermore, JP-A No. 60-240715 describes a composition that provides resistance to electroplating.

In addition, since the additive method has many advantages, after drilling holes in the board, a plating protective film is printed on the board that has been fully activated or a board containing a catalyst, and the necessary conductor pattern is added only by electroless copper plating. Full additive method: Apply electroless copper plating to the entire surface, print a plating protective film, form the necessary conductor pattern by electroplating, and then remove the electroless copper plating other than the conductor pattern part of the plating protection 3i film. Studies have been conducted on methods such as a semi-additive method in which a copper-clad laminate is used and a part-additive method in which through-hole portions are formed using an electroless copper plating method.

As a protective film for these additive methods, a composition having excellent heat resistance and chemical resistance is proposed, for example, in Japanese Patent Publication No. 47182/1982.

[The invention tries to solve i! l! Title] However, the above-mentioned Japanese Patent Application Laid-Open No. 53-56018, Japanese Patent Publication No. 59-23723
The products proposed in Japanese Patent Publication No. 1885/1985 have excellent heat resistance or thermal shock resistance, which is the purpose of the proposal, but when used as resists for chemical plating described below, they have the following properties. Occurs with a problem.

In other words, instead of the conventional subtractive method of forming wiring patterns, copper wiring can be formed electrolessly only in the necessary areas, so etching of copper foil and treatment of its waste liquid can be omitted. Cost reduction can be achieved.

Chemical plating baths for additive methods, which have many advantages such as being able to improve the reliability of through holes, especially those with small diameters (0.4 ta or less), have a pH of 12 to 13 (20 Although it is treated under strong alkaline conditions of 60 to 80 degrees Celsius, it cannot be used under such harsh conditions.

Furthermore, the composition described in JP-A-60-240715 is essentially resistant to strong alkaline chemical plating because the pattern is formed using an alkaline developer.

Furthermore, the composition described in the above-mentioned Japanese Patent Publication No. 61-47182 cannot be photoengraved because it does not have photosensitivity.
It cannot handle fine wiring patterns, and there are limits to its usable range.

This invention was made in order to solve such problems, and it provides a photosensitive resin composition that has heat resistance and chemical resistance, can be used particularly for forming a protective film for chemical plating, and has improved adhesion to a substrate. The purpose is to obtain.

[Means to solve the problem]

The photosensitive resin composition of the present invention has the following formula: tal-formula (where k is 1 or 2; l is 1 or 2; m is l or 2;
Pl~(5-k) is a hydrogen atom or a methyl group, ~(4
-1) is a hydrogen atom or a methyl group, R1-(5-■) is a hydrogen atom or a methyl group, n is an integer from O to 20) A polyurethane polyurethane obtained by reacting acrylic monoester and having two or more (meth)acryloyl groups and two or more urethane bonds in one molecule.
meth)acrylate, [bl linear polymer compound fcl A polymerization initiator that generates free radicals upon irradiation with light, and at least one of fdl tetrazole and its derivatives.

[Effect]

Since the photosensitive resin composition of the present invention uses urethane (meth)acrylate of polyvalent aromatic isocyanate represented by formula (1) as an essential component, urethane acrylate from isocyanates other than the polyvalent aromatic isocyanate is used as an essential component. Method for use as a photosensitive resin composition (Special Publication No. 59
-23723, etc.) which do not show sufficient resistance to chemical plating solutions, show high thermal resistance.

An example of research on the thermal resistance of polyurethane is given in [Kobunshi Ronshu, Vol. 35. No. 3, 161
Page, 1978], and it has been shown that polyurethanes made from aromatic isocyanates exhibit the highest thermal resistance. Moreover, in this invention, not only the aromatic isocyanate is used, but also a polyfunctional component is selected as the aromatic isocyanate, so a high crosslinking density can be achieved, which makes it possible to further improve thermal resistance.

Further, in the present invention, the heterocyclic nitrogen-containing compound is used as an extremely effective material for improving the adhesion of a photoresist to a metal plate when a layer of the photosensitive resin composition of the present invention is provided on a substrate such as a metal plate. It is an effective ingredient, and has good adhesion to metal plates, especially when using a strongly alkaline plating solution, and prevents the occurrence of lifting of the layer of the photosensitive resin composition of this invention, discoloration of metal plates, etc. do.

〔Example〕

The photosensitive resin composition of the present invention has the following formula:
P, ~(5-k) is a hydrogen atom or a methyl group, g1 ~(4
-1) is a hydrogen atom or a methyl group, R1-(5-m) is a hydrogen atom or a methyl group, n is an integer from O to 20) Polyurethane poly(meth)acryloyl group and two or more urethane bonds in one molecule obtained by reacting acrylic acid monoester.
Contains meth)acrylate as an essential component. −
In formula (1), P, ~(5-k) are hydrogen atoms or methyl groups, Q1 ~ (4-1) are hydrogen atoms or methyl groups,
R1-(5--) is a hydrogen atom or a methyl group, and for example, when =2, Pl+ P2+ p indicates that they may be the same or different. Furthermore, alkyl groups greater than ethyl are not common because they are difficult to obtain. More k.

It is difficult to industrially obtain a polyvalent aromatic isocyanate represented by the general formula (RI) in which 1 and m is 3 or more, and this is not preferred.

n is an integer from θ to 20.

When n exceeds 20, the resulting polyurethane polyester
The viscosity of the (meth)acrylate becomes very high, making it unsuitable for use in this invention.

Examples of the (meth)acrylic acid monoester of dihydric alcohol include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate, which are preferably used.

These reactions - It is preferable to carry out the reaction so that the NCO equivalent of the isocyanate shown in formula (1) is approximately equal to the aquatic group equivalent of the dihydric alcohol acrylic acid monoester, but if the NGO equivalent is slightly smaller than the aquatic group equivalent, It doesn't matter if you run out.

In this specification, the term (meth)acrylic refers to acrylic and/or methacryl.

The linear polymer compound as the component contained in the photosensitive resin composition of the present invention includes vinyl copolymer polymers,
Any condensation/copolymer polymer can be used. However, vinyl copolymer linear polymers are preferable due to compatibility with the above-mentioned novolac type urethane (meth)acrylate compound and adhesion between the wiring board and the resin composition layer. The molecular weight of the polymer compound is 10.000~soo, ooo
Preferably, the range is .

If the molecular weight is less than 110,000, the thermal shock resistance decreases.
If it is more than 500.000, the compatibility will decrease.

An example of the vinyl monomer constituting the vinyl copolymer linear polymer is methyl methacrylate.

Butyl methacrylate, ethyl acrylate, isobutyl methacrylate, 2-hydroxyethyl methacrylate, 2
-Hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, glycyl methacrylate.

2.3-dibromopropyl methacrylate, acrylamide, acrylonitrile, tribromophenyl methacrylate, lolipromophenyl acrylate, vinyltoluene, styrene, α-methylstyrene, maleimide, N
-Phenylmaleimide.

Examples include, but are not limited to, N-isopropylmaleimide.

Examples of the polymerization initiator, which is the tc) component contained in the photosensitive resin composition of the present invention and which generates free radicals upon irradiation with light, include 2-ethylanthraquinone, 2-t-butylanthraquinone, octamethylanthraquinone, 1
．． Quinones such as 2-henzanthraquinone and 2.3-diphenylanthraquinone, α-ketaldonyl alcohols and ethers such as benzin, pivaloin, and acyloin ether, α-phenylbenzoin, α, α゛jetoxyacetophenone 5 benzophenone.

Examples include ketones such as 4.4'-bisdialkylaminobenzophenone and 2.4.5-) realarylimidazole dimers, which can be used as monomers or mixtures thereof.

The photosensitive resin composition of the example of this invention is 9, for example (al
20 to 80 parts by weight, preferably 30 to 60 parts by weight of the fat component, and 20 to 80 parts by weight, preferably 30 parts by weight of the middle component, so that the total amount of component (b) and component (C) is 100 parts by weight. 60 parts by weight, and 1 to 10 parts by weight of component (C), preferably 3 to 7 parts by weight.

If the proportion of the Al component used is less than 20 parts by weight, chemical plating solution resistance will decrease, and if it exceeds 1 part by weight, the thermal shock resistance will be poor. This reduces thermal shock resistance and chemical plating solution resistance.

If the tc+ component is less than 1 part by weight, the curability with ultraviolet rays will be lowered, causing a decrease in sensitivity, and if it exceeds 10 parts by weight, the sensitivity will improve, but the above-mentioned physical properties will deteriorate.

At least one of tetrazole and its derivatives, which are the dl components contained in the photosensitive resin composition of the present invention, can be added to the metal plate of the photoresist, for example, when a layer of the photosensitive resin composition is provided on a metal plate. It is an extremely effective component for improving the adhesion to the metal plate, and it has good adhesion to the metal plate even when a strong alkaline plating solution is used. Prevent the occurrence of discoloration, etc. Examples of the above compounds include nophenyltetrazole and 5-phenyltetrazole.

5-aminotetrazole, 5-amino-1 methyltetrazole, 5-amino-2 phenyltetrazole, 5-mercapto-1 phenyltetrazole.

Examples include 5-mercapto-1 methyltetrazole. The amount of these compounds added to the composition is not determined depending on the composition components and composition ratio of the photoresist and the hardness of the photoresist after photocuring, but the amount to obtain effective adhesion curing is determined depending on the composition of the composition. The content ranges from 0.001 to 9% by weight, preferably from 0.01 to 1.0% by weight. If it is too large, the sensitivity will decrease.

The photosensitive resin composition of the embodiments of the present invention may contain other accessory components, such as dyes and pigments for coloring, if necessary.
Thermal polymerization/inhibitor as a storage stabilizer.

Flame retardants, anti-aging additives, etc. can be added as appropriate.

Although the photosensitive resin composition of the present invention can be used in the absence of a diluent, it is possible to use solvents that dissolve the base resin and do not have a very high boiling point, such as methyl ethyl ketone, methylene chloride, or a methylene chloride/methyl alcohol mixture. ,
Preferable results can be obtained by using in combination with isopropyl alcohol and isopropyl alcohol. The amount of solvent used is 2
00% by weight or less, preferably 100 to 200% by weight.

Further, the photosensitive resin composition of the present invention can be applied to metal surfaces such as copper,
It is used by laminating it on nickel, chromium, preferably copper. How to use it: Apply it as a liquid resist to the metal surface, cover it with a protective film after drying, or use it as a liquid resist.
Alternatively, it can be used as a dry film photoresist laminated onto a metal surface. The thickness of the photoresist layer varies depending on the application, but the thickness after drying is preferably about 5 to 100 μm.

Polyethylene is used as a protective film when used as a liquid resist. An inert polyolefin film such as polypropylene is preferably used.

Dry film photoresists are made by coating a photopolymerizable resin composition on a polyester support film, and after drying, laminating a polyolefin protective film.

Exposure and development treatment after lamination can be carried out by conventional methods. That is, exposure is performed through a negative mask using a light source of a high-pressure mercury lamp or an ultra-high-pressure mercury lamp. After exposure, heat treatment is performed at 50 to 100°C for 10 to 30 minutes.

After peeling off the support film, development is performed using a developer. Is the developer 1.1.1 such as trichloroethane? A container is used. The use of non-thermal solvents is preferred for safety reasons.

The image-like protective film obtained by this method serves as a corrosion-resistant film for ordinary etching, plating, etc., but even better properties can be obtained by heat treatment at 80-200°C and irradiation with actinic light after development. It becomes a protective film with This treatment usually involves irradiation with active light, followed by heat treatment for 30 to 30 minutes.
Preferably, this is carried out for 60 minutes.

The protective film obtained by heat treatment after development and exposure to active light has sufficient resistance to organic solvents such as trichlene, methyl ethyl ketone, isopropyl alcohol, and toluene.
Resistant to acidic or alkaline aqueous solutions. moreover,
Since it has excellent heat resistance and cold shock resistance, it is suitable as a permanent protective coating for solder masks and the like that require long-term reliability.

Next, embodiments of this invention will be described. The examples shown here are illustrative of embodiments, and the invention is not limited thereto.

Examples 1 to 1 As a polyvalent aromatic isocyanate represented by the formula (RI), 450 parts by weight of Millionate MR-400 (manufactured by Nippon Polyurethane Industries) and 400 parts by weight of 2-hydroxyethyl acrylate. Polyurethane acrylate (PUA■) was obtained by reacting with.

Next, the polyurethane acrylate (PUA-1), a linear polymer, a photopolymerization initiator, and others were mixed in the proportions shown in Table 1 to obtain photosensitive resin compositions of Examples of the present invention. Note that the numerical values in Table 1 indicate parts by weight. Furthermore, prepare a resin liquid using methyl ethyl ketone as a solvent.
% concentration) This resin liquid was applied in the form of a polyethylene terephthalate film and dried by heating to obtain a photosensitive dry film having a layer thickness of the photosensitive resin composition of about 50 μm.

Characteristic Evaluation Test Through holes and component holes were formed in a glass epoxy copper-clad laminate having a base material thickness of 1.6 am and a copper foil thickness of 18 μm. Next, after performing catalyst treatment for electroless plating,
A wiring pattern was formed.

The photosensitive dry film was laminated onto this substrate using a laminator. After laminating, it was exposed using a negative mask, and then heated at 80°C for 10 minutes, and then 1.1.1
-) Spray development was performed using dichloroethane (20°C, 80 seconds). After development, it was dried at 80 °C for 5 minutes, and then heated at 2.5 °C using a high-pressure mercury lamp (80 W/cm).
J/ci pre-irradiation. Thereafter, heat treatment was performed at 15° C. for 30 minutes to form a protective film.

Next, electroless plating bath (PIT, 12.5 (20℃)
60° C.) for 15 hours, 20 hours, and 25 hours, and copper plating with a thickness of approximately 23 μm, 30 μm, and 38 μm was applied to the through holes, respectively. After electroless plating treatment,
After thoroughly rinsing with water, dry at 80℃ for 10 minutes,
Further, heat treatment was performed at 130° C. for 60 minutes. During this series of electroless plating treatments, the protective film did not deteriorate, blister, or peel, and showed sufficient resistance.Furthermore, as a soldering heat resistance test, it was immersed in a solder bath at 255 to 265°C for 10 seconds, but the protective film It was found to be stable, with no cracking or peeling observed, and was found to be suitable for use as a solder mask.

These results are summarized in Table 2.

Table Comparative Example 1 Urethane acrylate was synthesized in the same manner as in Example 1 using 336 g (4 equivalents) of hexamethylene diisocyanate and 533 g (4.1 mol) of hydroxyethyl methacrylate. A photosensitive dry film was prepared by preparing a solution of the photosensitive resin composition using the same procedure as above.The blending ratio was as follows.

Urethane acrylate 55 parts by weight PMB? lA 40 parts by weight M, K (Michler ketone) 0.5 parts by weight B, P
(Benzophenone) 4.5 parts by weight Comparative Example 2 A photosensitive resin composition was obtained in the same manner as in the example using the formulation shown in Table 1, and a photosensitive dry film was also obtained.

Characteristic Evaluation Test Using the photosensitive dry film obtained as described above, a protective film was formed on a substrate in the same manner as in the examples, and electroless plating treatment and a soldering heat resistance test were performed. the result,
In the case where the photosensitive dry film of Comparative Example 1 was used, after the electroless plating treatment, part of the surface of the protective film became cloudy and part of it was peeled off. In the solder heat resistance test, further blistering was observed at the peeled part, but no change was observed in other parts.

As described above, although the photosensitive resin composition of Comparative Example 1 could be used as a solder mask, it was difficult to use it as a protective film for chemical plating like the photosensitive resin composition of the present invention. .

The photosensitive dry film of Comparative Example 2 was 15
Electroless copper plating for several hours was successfully performed. However, after 20 hours of electroless copper plating, it was observed that the plating solution had penetrated into the wiring area under the resist near the through holes. Furthermore, a similar phenomenon was observed when electroless copper plating was performed for 25 hours.

In the solder heat resistance test, those plated for 15 and 20 hours performed well, but those plated for 25 hours showed peeling of the resist in areas where the plating solution penetrated.

〔Effect of the invention〕

As explained above, the present invention has heat resistance and chemical resistance by using the +81-formula (dl tetrazole and at least one of its derivatives), and is particularly suitable for forming a protective film for chemical plating. It is possible to obtain a photosensitive resin composition that can be used and has improved adhesion to a substrate.

Agent Masuo Oiwa (In the formula, k is 1 or 2. I is l or 2. m is 1 or 2,
P1~(5-k) is a hydrogen atom or a methyl group, ~(4
-1) is a hydrogen atom or a methyl group, R1-(5-m) is a hydrogen atom or a methyl group, and n is an integer from θ to 20) (meth) of polyvalent aromatic isocyanate and dihydric alcohol A polyurethane polyurethane obtained by reacting acrylic monoester and having two or more (meth)acryloyl groups and two or more urethane bonds in one molecule.
meth)acrylate, (bl linear polymer compound) A polymerization initiator that generates free radicals upon irradiation with TCI light, and

Claims (1)

[Claims] (a) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, k is 1 or 2, l is 1 or 2, m is 1 or 2,
P_1~(5-k) is a hydrogen atom or methyl group, Q_1~
(4-l) is a hydrogen atom or a methyl group, R_1~(5-m
) is a hydrogen atom or a methyl group, n is an integer of 0 to 20)) and a (meth)acrylic acid monoester of a dihydric alcohol are reacted, and each molecule contains 2 (b) a linear polymer compound; (c) a polymerization initiator that generates free radicals upon irradiation with light; (d) Photosensitive resin composition containing at least one of tetrazole and its derivatives