JPH0876378A - Metal surface protecting resin composition, laminated body using same and producing method of printed circuit board - Google Patents

Abstract

PURPOSE: To obtain a metal surface protecting resin compsn. undevelopable with a slightly alkaline aq. soln. and removable with a highly alkaline aq. soln. CONSTITUTION: This metal surface protecting resin compsn. contains 100 pts.wt., in total, of 50-80 pts.wt. copolymer having 4-12mol% carboxyl group content and a wt. average mol.wt. of 30,000-400,000 (A) and 20-50 pts.wt. ethylenically unsatd. compd. having >=100 deg.C b.p. under atmospheric pressure (B). The copolymer consists of at least one kind of polymerizable vinyl monomer having a carboxyl group as a 1st monomer, at least one kind of 2nd monomer selected from among alkyl acrylates and alkyl methacrylites each having a 3-8C alkyl group and giving a homopolymer whose glass transition temp. T2 is <=70 deg.C and at least one kind of 3rd monomer selected from among alkyl acrylates, alkyl methacrylates, hydroxyalkyl acrylates and hydroxyalkyl methacrylates each having a 1-2C alkyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal surface protective resin composition, a laminate using the same and a method for producing a printed circuit board.

[0002]

2. Description of the Related Art As a copper clad laminate used for manufacturing a printed circuit board, one having a structure in which copper foil is laminated on both surfaces of a glass cloth-epoxy resin sheet is widely used. Further, a photosensitive resin composition is widely used as a resist used for manufacturing a printed circuit board, and a photosensitive laminate (hereinafter referred to as a photosensitive film) in which the photosensitive resin composition is laminated on a support layer. Is also widely used.

The mainstream of these photosensitive films is the alkaline type, in which the uncured portion can be developed with a weak alkaline aqueous solution and the cured portion can be peeled with a strong alkaline aqueous solution. The printed circuit board is prepared by laminating a photosensitive layer of a photosensitive film on a copper clad laminate that has been polished or treated with chemicals, and then exposing the circuit pattern through a photo tool, and then removing the support to 0.5 to 2.0% by weight. The uncured portion is developed using a weak alkaline aqueous solution such as the sodium carbonate aqueous solution to form a resist image (cured portion) on the copper clad laminate.

Next, after the exposed copper surface outside the resist image area is etched with an etching solution, the resist image is peeled off using a strong alkaline aqueous solution such as 1.0 to 5.0% by weight of sodium hydroxide, and the printed circuit is printed. Produce a board. Conventionally, a printed circuit board in which a circuit is formed on both sides of a copper-clad laminate and a circuit is formed on only one side of the copper-clad laminate has been the mainstream, but in recent years, along with the versatility of printed circuit boards, There is a demand for a printed circuit board in which a circuit is formed on one surface of a copper-clad laminate and copper foil is left on the other surface of the laminated board without forming a circuit.

In order to meet this requirement, in the conventional method, a photosensitive layer of a photosensitive film is laminated on a copper clad laminate, and then one side (hereinafter referred to as A side) is exposed with a circuit pattern through a photo tool and the other side is exposed. The surface (hereinafter referred to as surface B) is exposed on the entire surface, and the printed circuit board is manufactured through development, etching, and peeling. When a foreign substance is present on the surface B during exposure, the foreign substance portion becomes an uncured portion, and eventually the copper foil is etched in the etching process, which causes a defect.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and it is impossible to develop the surface B with a weak alkaline aqueous solution and peelable with a strong alkaline aqueous solution. The present invention provides a metal surface protective resin composition that eliminates the number of exposure steps and can eliminate defects caused by adhesion of foreign matter, a laminate using the same, and a method for manufacturing a printed circuit board.

[0007]

According to the present invention, (A) at least one vinyl-polymerizable first monomer having a carboxyl group, a homopolymer having a Tg of 70 ° C. or less, and at least one carbon number of 3 to 3 are used. A second monomer selected from alkyl acrylates and alkyl methacrylates having 8 alkyl groups, and alkyl acrylates having at least one alkyl group having 1 to 2 carbon atoms, alkyl methacrylates, hydroxyalkyl acrylates and hydroxyalkyl methacrylates. 50 to 80 parts by weight of a copolymer of a third monomer, which has a carboxyl group content of 4 to 12 mol% and a weight average molecular weight of 30,000 to 400,000. ) 20% of the ethylenically unsaturated compound having a boiling point of 100 ° C. or higher at normal pressure
~ 50 parts by weight (however, the total amount of (A) and (B) should be 100 parts by weight), which cannot be developed with a weak alkaline aqueous solution and can be peeled with a strong alkaline aqueous solution. It relates to a resin composition. Also, the present invention
The present invention relates to a laminate obtained by applying the metal surface protection resin composition on a support and drying the composition. In the present invention, a photosensitive film is laminated on one surface (A surface) of a copper clad laminate, the above laminate is laminated on the other one surface (B surface), and the A surface is exposed in a pattern to weakly expose it. The present invention relates to a method for producing a printed circuit board, which comprises developing an unexposed portion of the A side with an alkaline aqueous solution, then performing an etching treatment, and then peeling off the resin on the A side and the B side with a strong alkaline aqueous solution.

Next, the components contained in the metal surface protective resin composition of the present invention will be described in detail. The vinyl-polymerizable first monomer used in the copolymer (A) in the present invention imparts brittleness to the copolymer, and examples thereof include acrylic acid, methacrylic acid, fumaric acid, cinnamic acid, Crotonic acid,
Examples thereof include propiolic acid, itaconic acid, maleic acid, maleic anhydride, maleic acid half ester and the like, and these are used alone or in combination of two or more kinds.
Of these, methacrylic acid is preferred. If the carboxyl group content of the copolymer is less than 4 mol%, the copolymer cannot be removed with a strong alkaline aqueous solution, and if it exceeds 12 mol%, the copolymer is developed (affected) by a weak alkaline aqueous solution.
The content of the carboxyl group in the (A) copolymer is preferably in the range of 5 to 8 mol%.

The second monomer is for imparting flexibility, chemical resistance to etching treatment liquid and the like, and peeling property to strong alkaline aqueous solution, and Tg of the homopolymer is 70.
Selected from alkyl acrylates and alkyl methacrylates having an alkyl group having a carbon number of 3 to 8 and having a carbon number of 3 to 8, for example, propyl (meth) acrylate (the meaning of acrylate and methacrylate, the same applies hereinafter), butyl (meth) acrylate, octyl (Meth) acrylate and the like can be mentioned, and these can be used alone or in combination of two or more kinds. The preferable amount thereof is 10 to 30 mol% based on the copolymer (A). Tg of homopolymer is 7
The reason why the second monomer at 0 ° C. or lower is used is to lower the Tg of the copolymer (A) to be obtained so as to fall within a preferable range.
The amount of the second monomer is closely related to the brittleness together with the first monomer, and when the amount of the second monomer is large, the content of the carboxyl group of the copolymer is 4 to 12 mol%. Even within this range, if the amount of the second monomer exceeds 30 mol% with respect to the copolymer (A), the peelability tends to be poor.

The third monomer imparts adhesiveness to the metal substrate of the resist, and is selected from alkyl (meth) acrylates having a C 1 -C 2 alkyl group and hydroxylalkyl (meth) acrylate, for example, methyl ( (Meth) acrylate, ethyl acrylate, hydroxylmethyl (meth) acrylate, hydroxylethyl (meth) acrylate and the like, which may be used alone or in combination with 2
Used in combination with more than one type. Of these, methyl methacrylate is preferred.

The molecular weight of the (A) copolymer is a factor that imparts film-forming property and secondly determines developability, peelability and resistance to a processing solution. This molecular weight range should be such that the weight average molecular weight is 30,000 to 400,000, preferably 50,000 to 300,000.
00. When the weight average molecular weight is less than 30,000, the film formability is impaired and the resistance to the weak alkaline aqueous solution is lowered. The weight average molecular weight is 400,
If it exceeds 000, the film formability and resistance are very good, but peeling becomes difficult. Further, the Tg of the copolymer is preferably in the range of 60 to 100 ° C. because of the flexibility of the film.

The ethylenically unsaturated compound (B) in the present invention has at least one terminal ethylenically unsaturated group.
It may be any liquid-addition-polymerizable substance having an individual number and a boiling point of 100 ° C. or higher at normal pressure, and examples thereof include those obtained by adding α, β-unsaturated carboxylic acid to polyhydric alcohol, for example, , Tetraethylene glycol di (meth)
Acrylate, di (meth) acrylate of polyoxyalkylenated bisphenol A, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) ) Acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, polypropylene glycol di (meth) acrylate (having 2 to 14 propylene groups), dipentaerythritol penta (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, a compound obtained by adding an α, β-unsaturated carboxylic acid to a glycidyl group-containing compound, for example, trimethylolpropane triglycidyl ether triacryl Rate, bisphenol A diglycidyl ether diacrylate, etc., polyvalent carboxylic acid,
For example, a substance having phthalic anhydride or the like and a hydroxyl group and an ethylenically unsaturated group, for example, β-hydroxyethyl (meth)
There are ester compounds with acrylates. These are used alone or in combination of two or more.

The amount of the (A) copolymer is 50 to 80 parts by weight. When the amount is less than 50 parts by weight, the resin layer is softened and cold flow occurs during storage when the laminate is formed. If it exceeds 80 parts by weight, the resin layer becomes brittle and peels off during lamination. The amount of the (B) ethylenically unsaturated compound is 20 to 50 parts by weight (the total amount of the (A) copolymer and the (B) ethylenically unsaturated compound is 100 parts by weight).

Generally, it is preferable to add a radical polymerization inhibitor to the resin layer in order to prevent thermal polymerization during the heating step and during storage. Radical polymerization inhibitors include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, phenothiazine,
Pyridine, nitrobenzene, dinitrobenzene, p-toluquinone, chloranil, aryl phosphite and the like are used, but it is preferable that they have a low volatility at 200 ° C. or lower, such as alkyl-substituted hydroquinone, tert-butylcatechol, and chloride. Cuprous, 2,6-di-tert-butyl p-cresol, 2,2-methylenebis (4-ethyl-6-t-butylphenol), 2,2-
Methylene bis (2-methyl-6-t-butylphenol) and the like. Further, in order to improve the stability of the resist after being laminated on copper, benzotriazole, benzotriazole hydrochloride, benzotriazole organic acid salt, aminobenzothiazole, etc. Copper antioxidants may be added.

The resin layer may contain coloring substances such as dyes and pigments. It is preferable that the coloring substance does not affect the characteristics of the photoresist and does not decompose or volatilize at a temperature of 200 ° C. or lower. Examples of colorants that can be used include fuchsin, auramine base, chalcocide green S, paramagenta, crystal violet, methyl orange, Nile blue 2B, Victoria blue, malachite green, basic blue 20, iodink green, night green B, Tripalosan, New Magenta, Acid Violet RRH,
Red Violet 5RS, New Methylene Blue GG
Etc. Further, additives such as a plasticizer such as tetraethylene glycol and diacetate and an adhesion promoter may be added to the resin layer.

The polymer film laminated on at least one surface of the resin layer includes, for example, a film made of polyethylene terephthalate, polypropylene or polyethylene, and a polyethylene terephthalate film is preferable. Since these must be removable from the resin layer later, they must not be made of a material that cannot be removed or surface-treated. The thickness of these films is appropriately 5 to 100 μm, preferably 1
It is 0 to 30 μm. Alternatively, one of these films may be laminated on both sides of this resin layer as a support film for the resin layer and the other as a protective film for this resin layer.

In order to form a laminate, first, the metal surface protection resin composition is uniformly dissolved in a solvent. The solvent may be any solvent as long as it dissolves the metal surface protection resin composition, and one or several kinds of solvents may be used. As the solvent, for example, general solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, dichloromethane, chloroform, methyl alcohol, ethyl alcohol are used. Next, the solution of the metal surface protective resin composition is uniformly applied on the above-mentioned polymer film as the support film layer, and then the solvent is removed by heating and / or blowing with hot air to form a dry film. The thickness of the dry film is a normal thickness and is not particularly limited and is preferably 10 to 100 μm, preferably 20.
-60 μm.

The laminate comprising the two layers of the resin layer and the polymer film is stored as it is or after further laminating a protective film on the other surface of the resin layer and wound into a roll.

In the production of a printed wiring board in which a circuit is formed on the side A and a copper foil is entirely left on the side B, the laminate of the present invention is used after removing the protective film, if present, from the protective film. The resin layer is laminated by being pressed against the copper clad laminate B surface while heating. Further, since it is necessary to form a circuit on the A side, a photosensitive film conventionally used for manufacturing a printed circuit board is laminated by a method similar to the above laminating method. Next, the surface A is exposed in a pattern through a photo tool, and the surface B is not exposed. After that, if a polymer film is present on the surface of the photosensitive film or the laminate, remove it, and
Using a weakly alkaline aqueous solution such as a 5 to 3.0% sodium carbonate aqueous solution, the unexposed portion of the surface A is developed by a known method, for example, spraying, rocking dipping, scraping or the like. At this time, the resin layer on the B side remains without being developed. Then, after the etching treatment, the resin on the surface A and the surface B is peeled off using a strong alkaline aqueous solution such as 1.0 to 5.0% by weight of sodium hydroxide.

[0020]

EXAMPLES The present invention will be described below with reference to examples. Example 1

[Table 1] A metal surface protective resin composition made of the materials shown in Table 1 was prepared and uniformly applied onto a polyethylene terephthalate film having a thickness of 20 μm, and the composition was dried in a hot air convection dryer at 100 ° C. for about 3 times.
Dried for minutes. The thickness of the resin layer after drying was about 25 μm. Then, the composition layer was laminated on a copper clad laminate having a clean surface by heating and pressing with a rubber roll so that the composition layer was in contact with the copper surface. Thereafter, the polyethylene terephthalate film was removed, and spray development was carried out for 60 seconds with a 1.0 wt% sodium carbonate aqueous solution. After that, use cupric chloride etching solution
Spray etching was performed for 00 seconds. After that, spraying was performed for 100 seconds with a 3.0 wt% sodium hydroxide aqueous solution. As a result, this composition was not attacked by the developing solution and the etching solution. Also, it could be peeled off with peeling liquid.

Comparative Example 1

[Table 2] The copolymer A of the metal surface protection resin composition of Example 1 is shown in Table 2.
Example 1 with the same composition except that the copolymer B shown in FIG.
It evaluated by the method similar to. As a result, this composition was not attacked by the developing solution and the etching solution. However, it was a peeling liquid and I couldn't peel it.

Comparative Example 2

[Table 3] The copolymer A of the metal surface protection resin composition of Example 1 is shown in Table 3.
The same composition was used, except that the copolymer C was changed to the one shown in FIG. As a result, this composition
Attacked by developer.

Comparative Example 3

[Table 4] The copolymer A of the metal surface protection resin composition of Example 1 is shown in Table 4.
Example 1 with the same composition except that the copolymer D shown in FIG.
Evaluation was performed in the same manner as in. As a result, this composition
It was not attacked by the developing solution and the etching solution. However, I couldn't peel it with peeling liquid.

[0024]

As described above, according to the present invention, it is possible to reduce the number of exposure steps and to easily manufacture a printed circuit board with high yield and high precision.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display area H05K 3/06 J H // B32B 15/08 E (72) Inventor Hajime Kakumaru Hitachi City, Ibaraki Prefecture 4-13-1 Higashimachi Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (3)

[Claims] 1. An alkyl acrylate having (A) at least one vinyl-polymerizable first monomer having a carboxyl group and a homopolymer having a Tg of 70 ° C. or less and at least one alkyl group having 3 to 8 carbon atoms. And a second monomer selected from alkyl methacrylate and a third monomer selected from alkyl acrylate, alkyl methacrylate, hydroxyalkyl acrylate and hydroxyalkyl methacrylate having at least one type of alkyl group having 1 to 2 carbon atoms. And a carboxyl group content of 4 to 12 mol% and a weight average molecular weight of 30,
50 to 80 parts by weight of a copolymer of 000 to 400,000 and (B) 20 to 50 parts by weight of an ethylenically unsaturated compound having a boiling point of 100 ° C. or more at normal pressure (provided that (A) and (B)). Of 100% by weight), which does not develop with a weakly alkaline aqueous solution and can be peeled with a strongly alkaline aqueous solution. 2. A laminate obtained by applying the metal surface protection resin composition according to claim 1 on a support and drying the composition. 3. A copper-clad laminate is laminated with a photosensitive film on one side (A side), and the other side (B side) is laminated with the laminate according to claim 2, and the A side is exposed in a pattern. A method for producing a printed circuit board, which comprises developing an unexposed portion of surface A with a weak alkaline aqueous solution, then performing etching treatment, and then peeling off the resin on surfaces A and B with a strong alkaline aqueous solution.