JPH0627665A - Photosensitive resin composition and its use - Google Patents

Abstract

PURPOSE:To provide a photosensitive resin compsn. ensuring satisfactory adhesion of a resist to a copper substrate at the time of immersion in a plating bath, having such excellent plating resistance as to suppress unnecessary plating and ensuring excellent removability and dispersibility of the resist in a plating removing process and to provide a laminate for a dry film resist using the photosensitive resin compsn. CONSTITUTION:This photosensitive resin compsn. contains a base polymer, an ethylenic unsatd. compd. and a photopolymn. initiator and the base polymer is an arylic copolymer consisting of 40-80wt.% (meth)-acrylate, 15-40wt.% (meth) acrylic acid and 2-40wt.% alkyl 2-(1-hydroxymethyl)acrylate.

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 and a laminate thereof, and more specifically to the production of printed wiring boards,
The present invention relates to a photosensitive resin composition having particularly excellent plating resistance as an etching resist or plating resist used for precision machining of metals and the like, and peeling dispersibility at the time of resist peeling.

[0002]

Use of a photosensitive resin composition and a dry film resist laminate using the same as a resist material such as an etching resist or a plating resist in the fields of manufacturing printed wiring boards, precision processing of metals and the like. It has been known. Conventionally, there are two types of methods for forming a resist in the production of printed wiring boards, precision processing of metals, etc., including a tenting method and a plating method. The tenting method protects the copper through holes for chip mounting with a resist and forms an electric circuit through etching and resist stripping, while the plating method deposits copper in the through holes by electroplating. Then, it is protected by solder plating, and an electric circuit is formed by removing resist and etching.

Therefore, the photosensitive resin compositions used in these methods are required to have sufficient adhesion, that is, resistance to plating, to withstand immersion in a strong acid plating bath for a long time. As a method for improving such adhesion, there are techniques disclosed in Japanese Patent Application Laid-Open Nos. 2-113252 and 3-122647.
In JP-A-2-113252, acrylates such as 2-hydroxypropyl methacrylate and 2-hydroxyethyl methacrylate are added to an acrylic copolymer of a base polymer, and in JP-A-3-122647, methacrylic acid acetoacetoxy is also used. The adhesion is improved by using ethyl etc.

[0004]

However, in the above-mentioned prior art, although the adhesive force of the resist is improved, the peeling dispersibility of the resist in the subsequent resist peeling process becomes a problem. That is, it is desirable to peel the resist when it is finely crushed, and the conventional technique has a defect that such characteristics are inferior.

[0005]

[Means for Solving the Problems] The inventors of the present invention have made earnest studies in view of such circumstances, and as a result, in a resin composition containing a base polymer, an ethylenically unsaturated compound and a photopolymerization initiator, (Meth) acrylic acid ester 40 to 80% by weight, (meth) acrylic acid 15 to 4
A photosensitive resin composition using an acrylic copolymer composed of 0% by weight and 2- (1-hydroxymethyl) acrylic acid alkyl ester 2 to 40% by weight adheres to a copper substrate of a resist when immersed in a plating bath. It has been found that the present invention has excellent properties, has less plating, and has excellent stripping dispersibility of the resist in the stripping step, and has completed the present invention. The present invention is described in detail below.

The base polymer used in the present invention includes (meth) acrylic acid ester, (meth) acrylic acid and 2- (meth) acrylic acid ester.
It is an essential condition to contain an acrylic copolymer composed of (1-hydroxymethyl) acrylic acid alkyl ester. Here, as the (meth) acrylic acid ester, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2
-Ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate and the like are exemplified. It The 2- (1-hydroxymethyl) acrylic acid alkyl ester is a compound represented by Chemical formula 1 and can be obtained by a method of reacting an acrylic acid alkyl ester with formaldehyde in the presence of a tertiary amine. .

[0007]

[Chemical 1] Here, R is an alkyl group in which C is about 1 to 6, and specifically, methyl, ethyl, n-propyl, i-butyl, n
-Butyl, n-hexyl and the like are exemplified.

In the acrylic copolymer, (meth)
The content of acrylic ester needs to be 40 to 80% by weight, and preferably 55 to 75% by weight.
If the content of the (meth) acrylic acid ester is low, the copolymer will be inferior in flexibility, and if the content is high, on the contrary, the copolymer will be prone to problems such as cold flow, which is not preferable. The content of (meth) acrylic acid is required to be 15 to 40% by weight, preferably 15 to 30% by weight. When the content of (meth) acrylic acid is small, swelling peeling occurs at the time of peeling the resist, and conversely, when it is large, the developer resistance tends to be poor.
Further, the content of 2- (1-hydroxymethyl) acrylic acid alkyl ester needs to be 2 to 40% by weight, preferably 5 to 30% by weight. When the content of 2- (1-hydroxymethyl) acrylic acid alkyl ester is small, the adhesion to the copper substrate is poor, and when it is large, the development time is short and the water resistance is low.

In addition to the above main components, other copolymerizable monomers may be used if necessary, and examples of the monomers include acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate. , Alkyl vinyl ether and the like. In addition to the above acrylic copolymer, a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin or the like can be used in combination with the base polymer. The weight average molecular weight of the base polymer is 40
It is preferably in the range of 000 to 200,000. If the molecular weight is small, cold flow is likely to occur. On the contrary, if the molecular weight is large, it is difficult to develop, the resolution is lowered, and the peeling dispersibility at the time of peeling the resist is poor.

Examples of the ethylenically unsaturated compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate. , Butylene glycol di (meth)
Acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexane glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (Meth) acrylate, dipentaerythritol penta (meth) acrylate, 2,2-bis (4-
(Meth) acryloxydiethoxyphenyl) propane,
2,2-bis- (4- (meth) acryloxypolyethoxyphenyl) propane, 2-hydroxy-3- (meth)
Acryloyloxypropyl (meth) acrylate, ethylene glycol diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, phthalic acid diglycidyl ester di (meth) acrylate, glycerin polyglycidyl ether poly (meth) acrylate, etc. The polyfunctional monomer of is mentioned. An appropriate amount of a monofunctional monomer may be used together with these polyfunctional monomers.

Examples of monofunctional monomers are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 2-phenoxy-2-hydroxypropyl (meth) acrylate. , 2- (meth) acryloyloxy-2-hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl (meth) acrylate,
Examples thereof include glycerin mono (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, half (meth) acrylate of a phthalic acid derivative, and N-methylol (meth) acrylamide.

The ratio of the ethylenically unsaturated compound to 100 parts by weight of the base polymer is preferably selected from the range of 10 to 200 parts by weight, particularly 40 to 100 parts by weight.
Excessive amount of ethylenically unsaturated compound causes poor curing, lowering of flexibility, delay of development speed, etc. Excessive amount of ethylenically unsaturated compound causes increase of tackiness, cold flow, decrease of peeling rate of cured resist, etc. .

As the photopolymerization initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, benzyl diphenyl disulfide, benzyl dimethyl ketal, dibenzyl, diacetyl, anthraquinone, naphthoquinone,
3,3′-dimethyl-4-methoxybenzophenone, benzophenone, p, p′-bis (dimethylamino) benzophenone, p, p′-bis (diethylamino) benzophenone, pivaloin ethyl ether, 1,1-dichloroacetophenone, p-t-butyldichloroacetophenone, hexaarylimidazole dimer, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-
Diethylthioxanthone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-dichloro-4-phenoxyacetophenone, phenylglyoxylate, α-hydroxyisobutylphenone, dibezosparone, 1- (4 -Isopropylphenyl) -2-hydroxy-2-methyl-1-propanone, 2-methyl- [4- (methylthio) phenyl]
-2-morpholino-1-propanone, tribromophenyl sulfone, tribromomethylphenyl sulfone, N
-Phenylglycine and the like are exemplified. The mixing ratio of the photopolymerization initiator is appropriately about 1 to 20 parts by weight based on 100 parts by weight of the total amount of the base polymer and the ethylenically unsaturated compound.

In addition to the photosensitive resin composition of the present invention, dyes (coloring and coloring), adhesion promoters, plasticizers, antioxidants, thermal polymerization inhibitors, solvents, surface tension modifiers, stabilizers. Additives such as a chain transfer agent, a defoaming agent, and a flame retardant can be appropriately added. The production of a dry film resist laminate using the photosensitive resin composition of the present invention and a method of producing a printed wiring board using the same will be described.

(Layering Method) The above-mentioned photosensitive resin composition is
After coating this on the base film surface such as polyester film, polypropylene film, polystyrene film, polystyrene film from the coated surface,
A protective film such as a polyvinyl alcohol film is coated to obtain a dry film resist laminate. As applications other than the dry film resist, the photosensitive resin composition of the present invention, a dip coating method, a flow coating method,
It is also possible to directly form a photosensitive layer having a thickness of 10 to 150 μm on the (copper) substrate to be processed directly by a conventional method such as a screen printing method. At the time of coating, a solvent such as methyl ethyl ketone, methyl cellosolve acetate, ethyl cellosolve acetate, cyclohexane, methyl cellosolve, methylene chloride, or 1,1,1-trichloroethane can be added.

(Exposure) In order to form an image with a dry film resist, the adhesive strength between the base film and the photosensitive resin composition layer and the adhesive strength between the protective film and the photosensitive resin composition layer are compared to determine the adhesive strength. After peeling off the lower film, the photosensitive resin composition layer side is attached to a metal surface such as a copper surface of a copper-clad substrate, and then a pattern mask is brought into close contact with the other film for exposure. When the photosensitive resin composition does not have tackiness, the other film may be peeled off and then the pattern mask may be brought into direct contact with the photosensitive resin composition layer for exposure. When a metal surface is directly coated, a pattern mask is brought into contact with the coated surface directly or through a polyester film or the like, and the surface is exposed. The exposure is usually carried out by ultraviolet irradiation, and as the light source at that time, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp and the like are used. After irradiation with ultraviolet rays, heating can be performed as necessary to achieve complete curing.

(Development) After exposure, the film on the resist is peeled off and developed. Since the photosensitive resin composition of the present invention is a dilute alkali developing type, the development after exposure is
1-2% by weight of alkali such as sodium carbonate and potassium carbonate
Perform using a dilute aqueous solution. (Etching, Plating) Etching is performed by an ordinary method using an etching solution such as ferric chloride aqueous solution or cupric chloride aqueous solution. In the plating method, after pretreatment using a plating pretreatment agent such as a degreasing agent or a soft etching agent, plating is performed using a plating solution.

(Removal and Removal of Cured Resist) Removal and removal of the cured resist is carried out by using an alkaline stripping solution composed of an aqueous alkali solution having a concentration of about 1 to 5% by weight such as sodium hydroxide and potassium hydroxide. INDUSTRIAL APPLICABILITY The photosensitive resin composition of the present invention and the dry film resist laminate of the composition are useful as an etching resist or a plating resist used in the production of printed wiring boards, precision processing of metals and the like.

[0019]

The photosensitive resin composition of the present invention uses an acrylic copolymer containing 2- (1-hydroxymethyl) acrylic acid alkyl ester as a base polymer, and therefore has excellent plating resistance and resist. It is also excellent in stripping dispersibility of the resist in the stripping step.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, "%" and "parts" mean weight basis unless otherwise specified. Examples 1 to 6 and Comparative Examples 1 to 8 The following bases of acrylic copolymers shown in Tables 1 and 2 were blended with the following ethylenically unsaturated compounds, photopolymerization initiators and additives to prepare dopes. The mixing ratio is
Base polymer: ethylenically unsaturated compound: photopolymerization initiator: additive = 54: 36: 9.15: 0.85 (% by weight).

Mixture of ethylenically unsaturated compound trimethylolpropane triacrylate / polyethylene glycol (600) dimethacrylate / ethylene oxide modified phthalic acid acrylate (manufactured by Kyoeisha Yushi Kogyo Co., Ltd.) in a weight ratio of 20/10/6.

Photopolymerization initiator -benzophenone 8.0 parts-p, p'-diethylaminobenzophenone 0.15 parts-2,2'-bis (o-chlorophenyl) 4,5,4,5-tetraphenyl-1, 2-Biimidazole 1.0 part Total 9.15 parts

Additive (dye) -Leuco crystal violet 0.8 parts-Malachite green 0.05 parts total 0.85 parts

Next, each dope was applied on a polyester film having a thickness of 20 μm by using an applicator having a gap of 10 mils, and allowed to stand at room temperature for 1 minute and 30 seconds.
The film was dried in an oven at 60 ° C., 90 ° C., and 110 ° C. for 3 minutes to form a dry film having a resist thickness of 50 μm (however, no protective film was provided). This dry film was placed on a copper-clad substrate preheated to 60 ° C in an oven at a laminating roll temperature of 100 ° C and a roll pressure of 3 kg.
/ Cm ² , and laminating speed was 1.5 m / sec.

(Evaluation of Sensitivity) A negative film for plating evaluation (a pattern mask having a line width and a space width of 80 μm and a pattern mask of 100 μm, respectively) was used on the obtained substrate, and
An exposure of 70 mj / cm ² was performed with a kW high pressure mercury lamp. At this time, a negative film (Stofer 2) made so that the light transmission amount gradually decreases so that the light sensitivity can be evaluated.
A one-step tablet) was used. Peel off the polyester film after 15 minutes from exposure, and 1% at 30 ℃
The unexposed part was removed by spraying an aqueous solution of sodium carbonate for 50-60 seconds. 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 substrate. (The higher the number of steps of this step tablet, the higher the light sensitivity.)

(Evaluation of Plating Migration) Next, after degreasing the above-mentioned developed substrate, it was washed with running water for 1 minute and immersed in an aqueous solution of sodium persulfate (110 g / l) / sulfuric acid (10 ml / l) for 2 minutes. After washing with running water for 1 minute, 1
It was immersed in a 0% sulfuric acid aqueous solution bath for 1 minute and washed again with running water for 1 minute. Then, it is placed in a copper sulfate plating bath [copper sulfate 75 g / l, sulfuric acid 190 g / l, chlorine ion 75 ppm, copper lime PCM (product of Meltex) 5 ml / l] and copper sulfate plating is performed at 25 ° C. and 2.5 A / dm ² . It went for 45 minutes. Immediately after the completion of copper sulfate plating, the plate is washed with water and then immersed in a 10% aqueous solution of borofluoric acid for 1 minute to obtain a solder plating bath [45% tin borofluoride 64 ml / l, 45% lead borofluoride 22 ml / l, 42% borofluoride. Hydrochloric acid 200 ml /
l, Pultin LA Conductivity Salt (product of Meltec) 20 g / l, Pultin LA Starter (product of Meltex) 40 ml / l] at 25 ° C.,
The plating treatment was performed at 2 A / dm ² for 15 minutes. After the solder plating was completed, it was washed with water and dried. After that, the presence or absence of chipping of the solder plating was observed from above with an optical microscope. (When the solder plating is removed, it is observed under the transparent resist.)

(Evaluation of borofluoric acid resistance) Further, the substrate after the development treatment was degreased and soft-etched in the same manner as above to obtain 42%.
It was placed in a 400 ml / l aqueous solution of borofluoric acid and left for 12 hours. Immediately after leaving, it was washed with water and visually observed for color loss of resist, surface condition, and adhesion to copper substrate.・ Evaluation criteria ○ ・ ・ ・ No color loss, good surface condition, good adhesion to copper substrate △ ・ ・ ・ Slight color loss and some resist peeled off from copper substrate × ・ ・ ・ Remarkable color loss Most of the resist is stripped from the copper substrate

(Resist stripping dispersibility) 21 steps are carried out in the same manner as in the case where sensitivity is evaluated using a negative film having a (10 cm × 20 cm) rectangular opening (light transmitting portion) for resist stripping dispersibility evaluation. After exposure with a step tablet so as to have 8 steps, it was developed with a 1% sodium carbonate aqueous solution. Then, the substrate after development was dipped in a beaker containing a 3% aqueous sodium hydroxide solution at 50 ° C., the resist (photo-cured coating) was peeled off, and the state of the peeled piece was visually observed.・ Evaluation criteria ○ ・ ・ ・ At least 6 to 7 cracks (on the resist) cause the cured resist to become minute pieces and peel off Δ ・ ・ ・ (At the resist) at least 2 to 3 cracks cause the cured resist to become small pieces and peel off × ・ ・ ・ 6cm × 10cm without cracking (on resist)
Peeling into a film as it is

[0029]

Table 1 Acrylic- based co-polymer (parts by weight) Example 1 MMA nBMA 2EHA MAA EtHMA molecular weight 56 4 11 23 6 85000 Example 2 MMA nBMA 2EHA MAA EtHMA molecular weight 52 4 11 23 3 10 90000 Example MMA nBMA 2EHA MAA EtHMA Molecular Weight 42 4 11 23 20 98000 Example 4 MMA nBMA 2EHA MAA nBHMA Molecular Weight 56 4 11 11 23 6 80000 Example 5 MMA nBMA 2EHA MAA nBHMA 4 A 56 A 11 BHMA 4 A 11 HMA 4 A 11 HMA 4 A 11HMA 4 A 11HMA 4A 11B HMA 4A 11BHMA 4A 11BHMA 4A 11HMA 4A 11HMA 4A 11BHMA 4A 11H 2AHA 2HHA 4A 11H 2 Molecular weight 42 4 11 23 20 90000 Table 1-Note) MMA; methyl (meth) acrylate, nBMA; n-butyl (meth) acrylate, 2EHA; 2-ethylhexyl (meth) acrylate , MAA; (meth) acrylic acid, EtHMA; 2- (1-hydroxymethyl) acrylic acid ethyl ester, nBHMA; 2- (1-hydroxymethyl) acrylic acid n-butyl ester

[0030]

Table 2 Acrylic- based co-polymer (parts by weight) Comparative Example 1 MMA nBMA 2EHA MAA EtHAM Molecular weight 66 5 11 16 2 85000 Comparative Example 2 MMA nBMA 2EHA MAA EtHAM Molecular weight 27 2 6 33 32 78000 Comparative Example 3 MMA nBMA 2EHA MAA EtHAM molecular weight 35 3 7 45 10 83000 Comparative Example 4 MMA nBMA 2EHA MAA nBHAM Molecular weight 55 4 11 11 10 15 80000 Comparative Example 5 MMA nBMA 2EHA MAA nBHAM 7 A 16B 2 AHA 2BHA 2AHA 16A 2AHA Molecular weight 60 4 12 23 1 80000 Comparative Example 7 MMA nBMA 2EHA MAA 2HEMA Molecular weight 56 4 11 23 6 90000 Comparative Example 8 MMA nBMA 2EHA MAA AAEMA Molecular weight 56 4 11 23 6 93000 Table 2-Note) MMA; methyl (meth) acrylate, nBMA; n-butyl (meth) acrylate, 2EHA; 2-ethylhexyl (meth) acrylate, MAA; (meth) acrylic acid, EtHMA; 2- ( 1-hydroxymethyl) acrylic acid ethyl ester, nBHMA; 2- (1-hydroxymethyl) acrylic acid n-butyl ester 2HEMA; 2-hydroxyethyl methacrylate, AAEMA; acetoacetoxyethyl methacrylate

Table 3 shows the evaluation results of the sensitivity, plating resistance (plating muzzle, borofluoric acid resistance) and peeling dispersibility of the photosensitive resin compositions obtained in Examples and Comparative Examples.

[Table 3] Sensitivity Plating chipping Boric acid resistance Resist stripping dispersibility Example 1 8.0 None ○ ○ Example 2 8.0 〃 ○ ○ Example 3 8.0 〃 ○ ○ Example 4 8.1 〃 ○ ○ Example 5 8.0 〃 ○ ○ Example 6 8.1 〃 ○ ○ Comparative Example 1 8.0 〃 ○ △ Comparative Example 2 7.6 Yes △ ○ Comparative Example 3 7.0 〃 × ○ Comparative Example 4 8 0.0 None ○ × Comparative Example 5 7.7 Yes △ ○ Comparative Example 6 8.0 〃 △ △ Comparative Example 7 8.0 None △ △ Comparative Example 8 8.1 〃 ○ △

[0032]

EFFECTS OF THE INVENTION The photosensitive resin composition obtained by the present invention and the dry film resist laminate using the same are said to have good adhesion of the resist to the copper substrate when immersed in the plating bath, and to reduce the amount of plating penetration. Since it is excellent in plating resistance and also excellent in resist dispersibility in the resist removing step, it is useful as an etching resist or a plating resist used in the production of printed wiring boards, precision processing of metals and the like.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03F 7/028 H05K 3/00 F 6921-4E

Claims (3)

[Claims] 1. A resin composition comprising a base polymer, an ethylenically unsaturated compound and a photopolymerization initiator, wherein the base polymer is (meth) acrylic acid ester 40 to 80.
% By weight, 15-40% by weight of (meth) acrylic acid and 2-
(1-Hydroxymethyl) acrylic acid alkyl ester, which is an acrylic copolymer composed of 2 to 40% by weight of a photosensitive resin composition. 2. The photosensitive resin composition according to claim 1, wherein the acrylic copolymer has a weight average molecular weight of 40,000 to 200,000. 3. A laminate for a dry film photoresist, comprising a layer of the photosensitive resin composition according to claim 1 or 2 formed between a base film and a protective film.