JP3199607B2 - Photosensitive resin composition and photosensitive element using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art Conventionally, in the field of manufacturing printed circuit boards, a photosensitive resin composition and a photosensitive element obtained using a support and a protective film have been widely used as a resist material for etching, plating and the like. Have been. The printed circuit board is formed by laminating a photosensitive film on a copper substrate, pattern-exposing, removing the unexposed portion with a developing solution, etching or plating, forming a pattern, and curing the cured portion. It is manufactured by a method of peeling off from the substrate.

[0002] With the recent increase in the density of printed wiring boards, the contact area between the copper substrate and the patterned photosensitive layer has become smaller. Chemical properties, flexibility, etc. are required.

[0003] Among these types of properties, a method of using a photopolymerizable compound having an isocyanurate ring in order to improve chemical resistance is disclosed in JP-A-61-77844 and JP-A-62-290705. Gazette, JP-A-61-14212
JP, JP-A-59-222480, JP-A-5-222480
No. 14190, JP-A-57-55914, JP-A-5-216224, JP-A-5-273754
However, there is a disadvantage that the cured film is hard and brittle.

[0004] On the other hand, a photosensitive resin composition having high sensitivity and low plating bath contamination is desired from the viewpoint of improving workability. It depends on the amount. Highly sensitive photoinitiators
German Patent No. 2,027,467, European Patent Publication No. 11,786, European Patent Publication No. 220, European Patent Publication No. 589, JP-A-6-69631, etc. However, these have the disadvantage of having plating bath contamination.

[0005] Photoinitiators with low plating bath contamination and high sensitivity are disclosed in JP-A-60-239744 and JP-A-2-22.
Although described in US Pat. No. 6149, there is a disadvantage that the sensitivity is insufficient. In addition, a photosensitive resin composition having high sensitivity by combining a dimer of 2,4,5-triphenylimidazole, which is a photoinitiator, with low plating bath contamination and a hydrogen-donating compound is disclosed in U.S. Pat. 3,479,1
No. 85, but when adjusted to the required sensitivity, increasing the amount of 2,4,5-triphenylimidazole dimer used has the disadvantage of increasing the line width of the resist, When the amount of the hydrogen donating compound used is increased, there is a disadvantage that adhesion to copper and storage stability are deteriorated. Further, it is conceivable to use a compound having an ethylenically unsaturated group which is highly reactive with 2,4,5-triphenylimidazole dimer (for example, polyethylene glycol dimethacrylate). Has the disadvantage of being significantly inferior.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and is excellent in mechanical strength, adhesion, chemical resistance, flexibility, light sensitivity, plating bath contamination and the like. And a photosensitive element using the same.

[0007]

The present invention provides (A) a binder polymer having a carboxyl group, and (B) 2,4,5.
A photoinitiator comprising a triphenylimidazole dimer and a photosensitive resin composition comprising (C) a photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule, wherein the component (C) Is represented by the general formula (I)

Embedded image [Wherein, R ¹ is each independently of the general formula (II)

Embedded image (Wherein, R ² represents a hydrogen atom or a methyl group;
14) or a general formula (III)

Embedded image (Wherein, R ² represents a hydrogen atom or a methyl group, and n is 1 to
An integer of 9 and m is an integer of 1 to 14)
A photosensitive resin composition which is a compound represented by the formula: The present invention also relates to a photosensitive element obtained by applying the photosensitive resin composition on a support and drying the composition.

The (A) binder polymer having a carboxyl group in the present invention includes, for example, a copolymer of acrylic acid or methacrylic acid and a vinyl monomer copolymerizable therewith. This copolymer is used alone or in combination of two or more.

Examples of the vinyl monomer include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, glycidyl acrylate, 2,2,2-trifluoroethyl Acrylate, 2,2,3,3-tetrafluoropropyl acrylate, methacrylate, acrylamide, diacetone acrylamide, styrene, vinyltoluene, etc. corresponding thereto are exemplified.

The acid value of the component (A) is preferably from 100 to 500, and the weight average molecular weight (measured by gel permeation chromatography (GPC) and converted by a calibration curve using standard polystyrene) is 20. 000
Preferably it is ~ 300,000. Acid value is 10
If it is less than 0, the developing time tends to be long, and if it exceeds 500, the developing solution resistance of the photocured resist tends to decrease. If the weight average molecular weight is less than 30,000, the developer resistance tends to decrease, and
If it exceeds 00, the developing time tends to be long.

In the present invention, (B) 2,4,5-triphenylimidazole dimer which is an essential component of the photoinitiator containing 2,4,5-triphenylimidazole dimer includes, for example, 2,2 2'-bis (o-chlorophenyl)
-4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,
4 ', 5,5'-tetrakis (m-methoxyphenyl)
Biimidazole, 2,2'-bis (p-carboxyphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p-chlorophenyl) -4,
4 ', 5,5'-tetrakis (p-methoxyphenyl)
-Biimidazole, 2,2'-di-o-tolyl-4,
4 ', 5,5'-tetraphenylbiimidazole, 2,
2'-di-p-tolyl-4,4'-di-o-tolyl-
5,5'-diphenylbiimidazole and the like.
These are used alone or in combination of two or more.

Examples of photoinitiators other than 2,4,5-triphenylimidazole dimer include aromatic ketones (benzophenone, N, N'-tetramethyl-4,4 '
-Diaminobenzophenone (Michler's ketone), N,
N'-tetramethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-ethylanthraquinone, phenanthrenequinone, etc., benzoin (benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, etc.) Benzoin ether, methyl benzoin, ethyl benzoin and the like, and benzyl derivatives (benzyl dimethyl ketal and the like). These are used alone or in combination of two or more.

In the present invention, (C) a compound represented by the above formula (I), which is an essential component of the photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule, n is an integer of 0 to 9, preferably 3 to 6. When n exceeds 9, the mechanical strength decreases. In addition, in the general formula (II) or the general formula (III), which is R ¹ in the general formula (I), m is
It is an integer of 1 to 14, preferably 4 to 14. When m exceeds 14, the chemical resistance decreases. Further, n is an integer of 1 to 9, and preferably 1 to 6. When n exceeds 9, the developability decreases.

The compound represented by the general formula (I) is, for example, a compound represented by the general formula (IV)

Embedded image (Where n is an integer of 1 to 9) and a compound represented by the general formula (V):

Embedded image (Wherein, R ² represents a hydrogen atom or a methyl group;
And an integer of 14). The above general formula (I)
In the compound represented by, a plurality of R ¹ in the formula may be different from each other, and the number of methylene groups or the number of ethylene glycol groups in R ¹ may be different.

Commercially available compounds represented by the above general formula (I) include, for example, NK Oligo UA-21
(Trade name of Shin-Nakamura Chemical Co., Ltd.) (In the general formula (I), R ¹
Is a general formula (III), and specifically,

Embedded image And the like).

The component (C) other than the compound represented by the above general formula (I) in the present invention includes, for example, a compound (polyethylene glycol) obtained by reacting an α, β-unsaturated carboxylic acid with a polyhydric alcohol. Diacrylate (having 2 to 14 ethylene groups), trimethylolpropane diacrylate, trimethylolpropane triacrylate, tetramethylolmethane triacrylate,
Α, β-unsaturated carboxylic acid to glycidyl group-containing compounds such as tetramethylolmethane tetraacrylate, polypropylene glycol diacrylate (having 2 to 14 propylene groups), dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, etc. (Bisphenol A dioxyethylene diacrylate, bisphenol A trioxyethylene diacrylate, bisphenol A decaoxyethylene diacrylate, and other bisphenol A dioxyethylene diacrylate, trimethylolpropane triglycidyl ether triacrylate, Bisphenol A diglycidyl ether acrylate, etc.), alkyl esters of acrylic acid (methyl acrylate,
Ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc.), and methacrylates corresponding to the above. These are used alone or in combination of two or more.

The amount of the component (A) in the present invention is as follows:
The amount is preferably from 40 to 80 parts by weight based on 100 parts by weight of the total of the components (A) and (C). When the compounding amount is less than 40 parts by weight, the photocured product is apt to become brittle,
When used as a photosensitive element, the coating properties tend to be poor, and when it exceeds 80 parts by weight, the sensitivity tends to be insufficient.

The amount of the component (B) in the present invention is as follows:
Preferably, the amount is 0.1 to 20 parts by weight based on 100 parts by weight of the total of the components (A) and (C). If the amount is less than 0.1 part by weight, the sensitivity tends to be insufficient. If the amount exceeds 20 parts by weight, the absorption on the surface of the composition during exposure increases, and the internal photo-curing increases. It tends to be insufficient. Further, 2,4, which is an essential component of the component (B),
The blending amount of the 5-triphenylimidazole dimer is as follows:
The amount is preferably 1 part by weight or more based on 100 parts by weight of the total amount of the components (A) and (C). If the amount is less than 1 part by weight, the sensitivity tends to be insufficient.

The amount of the component (C) in the present invention is as follows:
The amount is preferably 20 to 60 parts by weight based on 100 parts by weight of the total amount of the components (A) and (C). If the amount is less than 20 parts by weight, the sensitivity tends to be insufficient, and if it exceeds 60 parts by weight, the photocured product tends to be brittle. The compounding amount of the compound represented by the general formula (I), which is an essential component in the component (C), is not less than 3 parts by weight based on 100 parts by weight of the total of the components (A) and (C). Preferably, the amount is 5 to 40 parts by weight. If the amount is less than 3 parts by weight, sensitivity,
Adhesion, plating resistance, and the like tend to be poor.

The photosensitive resin composition of the present invention contains a hydrogen-donating compound (N-phenylglycine, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole) as long as the adhesion to copper and the storage stability are not reduced. , 2-
Mercaptobenzimidazole, etc.). Further, a dye, a color former, a plasticizer, a pigment, a flame retardant, a stabilizer, an adhesion promoter, and the like can be added to the photosensitive resin composition of the present invention as needed.

In the photosensitive resin composition of the present invention, the above components are dissolved in a solvent dissolving them, for example, toluene, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, chloroform, methylene chloride, By dissolving and mixing in methyl alcohol, ethyl alcohol and the like, a uniform solution can be obtained.

The photosensitive element of the present invention can be obtained by applying the above solution on a support and drying to form a photosensitive layer.

As the support, a polymer film (polyethylene terephthalate, polypropylene, polyethylene, etc.) is used, and among them, a polyethylene terephthalate film is preferable. Since these polymer films must be removable from the photosensitive layer later, they must not have been subjected to a surface treatment or made of a material that cannot be removed. The thickness of these polymer films is preferably 5 to 100 μm,
It is more preferable that the thickness be 30 μm. One of these polymer films is used as a support film for the photosensitive layer.
The other one may be laminated on both sides of the photosensitive layer as a protective film for the photosensitive layer.

In producing a photoresist image using the photosensitive element of the present invention, if the above protective film is present, after removing the protective film,
The photosensitive layer is laminated by pressing it against the substrate while heating. The surface to be laminated is not particularly limited, and usually, a metal surface is used. The heating temperature of the photosensitive layer is 90 to 130 ° C.
The pressure is preferably 3 kg / cm ² . If the photosensitive layer is heated as described above, it is not necessary to preheat the substrate in advance, but the substrate may be preheated to further improve the lamination property.

The photosensitive layer thus completed in lamination is
Next, using a negative film or a positive film, it is imagewise exposed to active light. At this time, if the polymer film present on the photosensitive layer is transparent, it may be exposed as it is, and if it is opaque, it must be removed naturally. From the viewpoint of protection of the photosensitive layer, the polymer film is transparent, and it is preferable to expose the polymer film while leaving the polymer film remaining. As the active light, a known active light source, for example, light generated from a carbon arc, a mercury vapor arc, a xenon arc, a flood lamp for photography, a sun lamp, or the like is used.

Next, after exposure, if a polymer film or the like is present on the photosensitive layer, it is removed, and then, using an aqueous alkali solution, for example, spraying, rocking immersion, brushing, scraping, etc. The unexposed portion is removed by a known method described above, and development is performed.

Examples of the base of the alkaline aqueous solution include alkali hydroxides (such as hydroxides of lithium, sodium or potassium), alkali carbonates (such as carbonates or bicarbonates of lithium, sodium or potassium), and alkali metal phosphates (such as carbonates or bicarbonates). Potassium phosphate, sodium phosphate and the like), alkali metal pyrophosphate (sodium pyrophosphate, potassium pyrophosphate and the like) and the like are used, and an aqueous solution of sodium carbonate is preferable. The pH of the aqueous alkali solution used for development is 9
To 11, and the temperature can be adjusted according to the developability of the photosensitive layer. In addition, a surfactant, an antifoaming agent, a small amount of an organic solvent for accelerating the development, and the like can be mixed in the aqueous alkali solution.

Further, when manufacturing a printed wiring board, the surface of the substrate exposed using the developed photoresist image as a mask is treated by a known method such as etching or plating. The photoresist image is then typically stripped with an aqueous solution that is more alkaline than the aqueous alkaline solution used for development. As the strong alkaline aqueous solution, for example, an aqueous solution of 1 to 5% by weight of sodium hydroxide is used.

[0029]

The present invention will be described below with reference to examples. Examples 1 to 4 and Comparative Examples 1 to 3 The materials shown in Table 1 were blended to obtain solutions. Next, the component (C) shown in Table 2 was dissolved in the obtained solution to obtain a solution of the photosensitive resin composition.

[0030]

[Table 1]

[0031]

[Table 2]

Next, the solution of the photosensitive resin composition is
The photosensitive element was uniformly coated on a 25 μm-thick polyethylene terephthalate film and dried for 10 minutes in a hot air convection dryer at 100 ° C. to obtain a photosensitive element. The dried film thickness of the photosensitive resin composition layer was 50 μm.

On the other hand, the copper surface of a copper-clad laminate (manufactured by Hitachi Chemical Co., Ltd., trade name: MCL-E-61), which is a glass epoxy material having a copper foil (thickness: 35 μm) laminated on both sides, is # 6
Polishing using a polishing machine with a brush equivalent to 00 (manufactured by Sankei Co., Ltd.), washing with water, drying with an air stream, heating the obtained copper-clad laminate to 80 ° C. Then, the photosensitive resin composition layer was laminated while being heated to 120 ° C.

Next, using an exposure machine (manufactured by Oak Co., Ltd.) HMW-201B having a high-pressure mercury lamp, a 21-step stofer tablet was placed on the test piece as a negative at 120 mJ / cm ² . Exposure. Next, the polyethylene terephthalate film was peeled off, and an unexposed portion was removed by spraying a 1% by weight aqueous solution of sodium carbonate at 30 ° C. for 60 seconds. Furthermore, the photosensitivity of the photosensitive resin composition was evaluated by measuring the number of steps of the step tablet of the photocured film formed on the copper-clad laminate, and the results are shown in Table 3. The light sensitivity is indicated by the number of steps of the step tablet. The higher the number of steps of the step tablet, the higher the light sensitivity.

Further, the line width (μm) remaining without peeling after the development was measured, and the results were shown in Table 3 as adhesion. The smaller the value of the adhesion is, the smaller the line is, the less the line is peeled off from the copper-clad laminate, indicating that the line is in close contact with the copper-clad laminate, indicating a higher adhesion.

Then, in the same manner as described above,
The exposed and developed substrate is immersed in a degreasing bath for 5 minutes → washed with water → soaked in a soft etch bath for 2 minutes → washed with water → 10% by weight sulfuric acid 1
Pretreatment in the order of immersion for minutes, put in a copper sulfate plating bath,
Copper sulfate plating was performed at room temperature at 3 A / dm ² for 40 minutes. Then, it is washed with water, immersed in 10% by weight of borofluoric acid for 1 minute, put in a solder plating bath, and solder-plated at room temperature.
Performed at 1.5 A / dm ² for 15 minutes. Degreasing bath; PC-455 (manufactured by Meltex) 25% by weight Soft etch bath; ammonium persulfate 150 g / l Copper sulfate plating bath; copper sulfate 75 g / l, sulfuric acid 190 g / l, chlorine ion 50 ppm, cover glyme PCM (meltex Solder plating bath: 45% by weight tin borofluoride 64ml / liter, 45% by weight lead borofluoride 22ml / liter, 42% by weight borofluoric acid 200ml / liter, Plutin LA Conductivity Salt (Meltex Co., Ltd.) 20g / liter, Plutin LA Starter (Meltex) 4
0ml / liter

After washing with water and drying, a cellophane tape was immediately applied to check the plating resistance, and the cellophane tape was peeled off in a vertical direction (90 ° peel-off test) to observe whether or not the resist had peeled off. The results were shown in Table 3 by observing the presence or absence of the solder plating under an optical microscope. When the solder plating is buried, solder deposited by plating is observed below the transparent resist through the transparent resist.

Further, another test piece was subjected to a cross-cut test (JIS-K-5400) after exposure and development with an exposure amount indicating eight steps using a 21-step stepper tablet, and the results are shown in Table 3.

[0039]

[Table 3]

As is apparent from Table 3, Examples 1 to 4 within the scope of the present invention have high photosensitivity and excellent plating resistance, adhesion and cross-cutting properties.

The photosensitive resin composition of the present invention has high photosensitivity and is excellent in adhesion, chemical resistance, flexibility, plating bath contamination and the like. The photosensitive resin composition of the present invention is further excellent in developability with an alkali developing solution. With the photosensitive resin composition of the present invention, a composition having further excellent mechanical strength can be obtained. The photosensitive element of the present invention comprises:
It has good developability with an alkaline developer and mechanical strength, and is excellent in workability.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-174521 (JP, A) JP-A-4-120541 (JP, A) JP-A-4-293052 (JP, A) JP-A-5-205 273754 (JP, A) JP-A-4-25846 (JP, A) JP-A-4-217252 (JP, A) JP-A-8-160615 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) G03F 7/027 G03F 7/004 G03F 7/031 H05K 3/06

Claims (9)

(57) [Claims] 1. A binder polymer having (A) a carboxyl group, (B) a photoinitiator containing 2,4,5-triphenylimidazole dimer, and (C) at least one polymerizable ethylenic compound in a molecule. In the photosensitive resin composition containing a photopolymerizable compound having an unsaturated group, one of the components (C) is represented by the general formula (I): [Wherein, R ¹ is each independently of the general formula (II): (Wherein, R ² represents a hydrogen atom or a methyl group;
14) or a general formula (III): (Wherein, R ² represents a hydrogen atom or a methyl group, and n is 1 to
An integer of 9 and m is an integer of 1 to 14)
A photosensitive resin composition which is a compound represented by the formula: 2. The photosensitive resin composition according to claim 1, wherein the component (A) has an acid value of 100 to 500 and a weight average molecular weight of 20,000 to 300,000. 3. The photosensitive resin composition according to claim 2, wherein the component (A) is a copolymer of methacrylic acid and a vinyl monomer copolymerizable therewith. 4. The photosensitive resin composition according to claim 1, further comprising an aromatic ketone as the photoinitiator of the component (B). 5. The photosensitive resin composition according to claim 1, wherein the compound represented by the general formula (I) as the component (C) is a compound wherein R ¹ is a compound represented by the general formula (III). . 6. The photosensitive resin according to claim 1, further comprising a compound obtained by reacting an α, β-unsaturated carboxylic acid with a polyhydric alcohol as the photopolymerizable compound as the component (C). Composition. 7. The compounding ratio of the component (A), the component (B) and the component (C) is 100 in total of the component (A) and the component (C).
Component (A) is 40 to 80 parts by weight with respect to parts by weight,
Component (B) is 0.1 to 20 parts by weight and component (C) is 20
The photosensitive resin composition according to any one of claims 1 to 6, wherein the content of the compound represented by formula (I) in component (C) is 3 parts by weight or more. 8. A photosensitive element obtained by applying the photosensitive resin composition according to claim 1 on a support and drying. 9. A photosensitive layer comprising the photosensitive resin composition according to claim 1, which is laminated on a substrate, exposed and developed, and the unexposed portion of the substrate surface is treated by etching or plating. A method for manufacturing a printed wiring board, comprising: