JPH07271032A - Crosslinking curable resin laminate - Google Patents

Abstract

(57) [Summary] [Purpose] To develop a cross-linking curable resin laminate for resists with high tent strength (development tenting property). [Structure] Between a support film and a protective film, a thermoplastic polymer (A) for a binder having a specific composition and a molecular weight in a specific range, and at least one having at least two ethylenically unsaturated groups in one molecule. A crosslinkable monomer (B),
A cross-linkable curable resin laminate comprising a layer of a cross-linkable curable resin composition comprising a photopolymerization initiator (C). [Effect] Even if the resist is thin, the tent strength is high, and in the tenting method, it is possible to achieve finer patterns, shorter working time, and reduced waste liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photopolymerizable or radiation polymerizable crosslinkable resin laminate which can be developed with an alkaline aqueous solution.

[0002]

2. Description of the Related Art In recent years, a so-called dry film resist having a structure in which a cross-linking curable resin layer is sandwiched between a protective film and a support film has been widely used as a photoresist for producing a printed wiring board. As the cross-linking curable resin layer, there are known a solvent developing type which develops and removes the unexposed area with a chlorine-based organic solvent and an alkaline developing type which develops and removes the unexposed area with an alkaline aqueous solution. Also, due to the advantage of manufacturing cost, the alkali development type dry film resist is becoming mainstream.

A method of using an alkali-developing dry film resist having a protective film and a support film is as follows. First, a protective film is peeled off from the dry film resist and a crosslinkable curable resin layer is laminated on a copper clad laminate by heat. Then, a phototool is brought into close contact with the support film surface of the resist film, and the portion to be cured is exposed and cured by ultraviolet rays or the like. Then, after removing the support film, the unexposed portion is developed and removed with a weak alkaline aqueous solution such as sodium carbonate to obtain a resist circuit pattern. Then, in the case of the copper through-hole method (tenting method), after the copper surface is etched, the hardened resist is peeled off with a strong alkaline aqueous solution such as sodium hydroxide to obtain a printed wiring board. In the case of the solder through-hole method (plating method), after the copper plating and the solder plating are performed, the cured resist is peeled off with a strong alkaline aqueous solution, and the exposed copper is etched to obtain a printed wiring board.

The above-mentioned tenting method is the mainstream of the printed wiring board manufacturing method because the manufacturing process is simple and the process control is easy as compared with the plating method. Conventionally, a resist having a thickness of 50 μm or more has been used for the tenting method, but in recent years, finer patterns, shorter manufacturing time,
There is a demand to reduce the thickness of the resist in order to reduce the amount of waste liquid. However, when the conventional resist is thinned, the tent strength of the resist on the through hole is not sufficient, and in particular, in a large through hole having a diameter of 5 mmφ or more, problems such as tearing of the tent occur during development.
Also, in order to prevent the undeveloped residue, etc., the developing tank is used twice or three times.
Since it may be passed around, a thinner resist having higher tent strength has been demanded.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to overcome the above-mentioned drawbacks, to provide high tent strength even when the resist thickness is thin, and to make fine patterns in the tenting method.
It is an object of the present invention to provide a cross-linking curable resin laminate that can achieve a reduction in working time and a reduction in waste liquid.

[0006]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that butyl acrylate is used as a copolymerization component of a thermoplastic polymer for a binder of a crosslinkable resin layer. As a result, they have found that the above objects can be achieved, and completed the present invention. That is, the present invention is a cross-linking curable resin laminate in which a cross-linking curable resin layer is provided between a support film and a protective film, wherein the cross-linking curable resin layer has 3 to 15 carbon atoms. 15 to 35% by weight of at least one kind (a-1) of the α, β-unsaturated carboxyl group-containing monomer having
It is composed of 5 to 30% by weight of butyl acrylate (a-2) and 35 to 80% by weight of methacrylic acid ester (a-3) having an alkyl group having 1 to 8 carbon atoms, and has a weight average molecular weight of 20000. The thermoplastic polymer for binder (A) in the range of 200,000, at least one crosslinkable monomer (B) having two or more ethylenically unsaturated groups in one molecule, and a photopolymerization initiator ( A cross-linking curable resin laminate comprising a cross-linking curable resin composition comprising C).

The present invention will be described below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing the structure of the cross-linking curable resin laminate of the present invention. In FIG. 1, 1 is a support film, 2
Indicates a crosslinkable curable resin layer, and 3 indicates a protective film.

The support film 1 in the present invention is not particularly limited, but conventionally used polyester films such as polyethylene terephthalate and polybutylene terephthalate are preferably used from the viewpoints of economy, heat resistance and releasability. The thickness of the support film 1 can be arbitrarily set according to the use conditions, but a thickness of 5 to 30 μm is used.

The crosslinkable curable resin layer 2 in the present invention comprises a thermoplastic polymer (A) for a binder and at least one crosslinkable monomer having at least two ethylenically unsaturated groups in one molecule ( It comprises a cross-linking curable resin composition composed of B) and a photoinitiator (C).

The thermoplastic polymer (A) for the binder which constitutes the cross-linking curable resin layer 2 in the present invention is 3 to 3 times so that it can be developed with a dilute aqueous alkali solution such as sodium carbonate.
It is necessary to contain at least one kind (a-1) of the α, β-unsaturated carboxyl group-containing monomer having 15 carbon atoms as a copolymer component. Useable α, β-unsaturated carboxyl group-containing monomer (a-1)
Examples of acrylic acid, methacrylic acid, cinnamic acid,
Crotonic acid, sorbic acid, itaconic acid, propiolic acid,
Examples thereof include maleic acid and fumaric acid, and their half-esters or anhydrides can also be used. The most preferred compounds among these are acrylic acid and methacrylic acid.

The content of the carboxyl group-containing monomer (a-1) in the thermoplastic polymer for binder (A) is 15
Is in the range of up to 35% by weight. If the content is less than 15% by weight, it cannot be developed by an alkaline aqueous solution or the development time is too long and the resolution is lowered. On the other hand, if the content is more than 35% by weight, the light left as a pattern is left. Since the hardened portion also swells with the alkaline developer and is easily removed, it becomes difficult to control development when obtaining a high resolution pattern, and the water resistance of the hardened portion also decreases.

Butyl acrylate is used as the component (a-2) which constitutes the thermoplastic resin (A) for the binder, and the content of the copolymer component in the thermoplastic resin (A) for the binder is in the range of 5 to 30% by weight. used. 5 used
If it is less than 10% by weight, the Tg of the crosslinkable curable resin composition becomes too high, resulting in poor embedding in the uneven surface of the substrate during lamination, and the effect of improving tent strength cannot be expected.
On the other hand, when the amount used exceeds 30% by weight, conversely, the Tg of the crosslinkable curable resin composition becomes too low and the storage stability of the dry film resist prepared decreases, and so-called cold flow easily occurs. Become.

In the present invention, it is essential to use butyl acrylate as the component (a-2), and examples thereof include n-butyl acrylate, s-butyl acrylate, t-butyl acrylate and i-butyl acrylate. To be Acrylate other than butyl acrylate, such as methyl acrylate, ethyl acrylate,
Even when acrylates such as n-propyl acrylate, i-propyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-ethylhexyl acrylate are used as the component (a-2), the time of development which is the object of the present invention No significant improvement in tent strength can be achieved.

The component (a-3) constituting the thermoplastic resin (A) for binder is copolymerized to give an appropriate Tg to the thermoplastic polymer for binder and has 1 to 8 carbon atoms. Is at least one kind of alkyl methacrylate having an alkyl group. Examples of these compounds include methylmethacrylate, ethylmethacrylate,
Examples thereof include n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, s-butyl methacrylate and t-butyl methacrylate. The most preferred of these compounds is methyl methacrylate. These methacrylate components are copolymerized so as to be in the range of 35 to 80% by weight in the thermoplastic copolymer (A) for binder.

The weight average molecular weight (Mw) of the thermoplastic polymer (A) for binders comprising the above-mentioned constituents used in the present invention is 20,000 to 200,000, preferably 5
It is in the range of 0000 to 150,000. When the weight average molecular weight of the thermoplastic polymer for binder (A) is less than 20,000, the film-forming property of the cross-linking curable resin layer of the obtained dry film resist is impaired, and sufficient film strength cannot be obtained, resulting in cold flow. It tends to occur and the tent strength during development becomes weak. On the other hand, when the weight average molecular weight of the thermoplastic polymer for binder (A) exceeds 200,000, the flexibility of the resulting cross-linking curable resin composition is lowered, and the embedding property into the irregularities on the copper-clad laminate surface and copper. The adhesive force with the stretched laminated plate is impaired.

The thermoplastic polymer (A) for binder used in the present invention is 45 to 75 in 100 parts by weight of the crosslinkable curable resin composition comprising the components (A), (B) and (C) of the present invention. Parts by weight, preferably 50 to 70 parts by weight. When the content of the thermoplastic polymer for binder (A) is less than 45 parts by weight, the film forming property of the crosslinkable curable resin layer of the obtained dry film resist is impaired, sufficient film strength cannot be obtained, and cold flow occurs. It is easy and peeling time becomes long. On the other hand, when the content of the thermoplastic polymer for binder (A) exceeds 75 parts by weight, the flexibility of the resulting cross-linking curable resin composition decreases, and the embedding property in the irregularities on the surface of the copper clad laminate is reduced. The adhesion with the copper clad laminate is impaired. Further, the cured film after exposure of such a resin composition loses gloss on the surface when developed, and may not have sufficient chemical resistance, particularly plating resistance and etching resistance.

Next, at least one crosslinkable monomer (B) (hereinafter referred to as crosslink) which constitutes the crosslinkable curable resin layer 2 of the present invention and has two or more ethylenically unsaturated groups in one molecule. The polymerizable monomer (B) will be described. Specific examples of the crosslinkable monomer (B) include 1,3-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol. Di (meta)
Acrylate, polypropylene glycol di (meth) acrylate, 2,2-bis [4- (meth) acryloyloxypolyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxypolypropyleneoxyphenyl] propane, hydroxypivalin Acid neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, glycerin tri (meth) acrylate, trimethylolethane di (meth) acrylate, trimethylolethane tri (meth) acrylate,
Trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane tris [polyethoxy (meth) acrylate], trimethylolpropane tris [polypropyleneoxy (meth) acrylate], isocyanuric acid triethyloldi (meth) acrylate , Isocyanuric acid triethylol tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate ) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate Poly (meth) acrylates of polyhydric alcohols such as rate, epoxy (meth) acrylates and urethane (meth) acrylate, and the like. These may be used alone or in combination.

The crosslinkable monomer (B) used in the present invention is contained in an amount of 25 to 5 per 100 parts by weight of the crosslinkable curable resin composition comprising the components (A), (B) and (C) of the present invention.
5 parts by weight are contained. Content of crosslinkable monomer (B) is 2
If the amount is less than 5 parts by weight, the gloss of the surface may be lost when developed with an alkaline aqueous solution. On the other hand, the crosslinkable monomer (B)
When the dry film resist is formed in an amount of more than 55 parts by weight, the unexposed resin portion becomes too flexible, and inconvenient problems such as cold flow are likely to occur.

The photopolymerization initiator (C) used for photopolymerizing the crosslinkable curable resin layer 2 in the present invention includes:
Known compounds such as benzophenone, Michler's ketone, 4,4'-bis (diethylamino) benzophenone, t-butylanthraquinone, 2-ethylanthraquinone, thioxanthones, benzoin alkyl ethers and benzyl ketals can be mentioned, and these are one kind. Or 2
Used in combination with more than one species.

When the photopolymerization initiator (C) used in the present invention is cured by ultraviolet rays, the total amount of the thermoplastic polymer (A) for binder and the crosslinkable monomer (B) is 100.
It is used in an amount of 0.1 to 10 parts by weight based on parts by weight. If the amount used is less than 0.1 parts by weight, the photo-curing does not sufficiently occur, while if the amount used exceeds 10 parts by weight, it becomes thermally unstable. Further, when the crosslinkable curable resin layer 2 of the present invention is cured with an electron beam, a photopolymerization initiator may not be contained.

The crosslinkable curable resin layer 2 of the present invention comprises
A polymerizable monomer having one ethylenically unsaturated group in one molecule may be added for the purpose of adjusting the crosslink density of the cured product and obtaining appropriate flexibility. Examples of this compound include phenoxydiethoxy (meth) acrylate,
Methoxy polyethylene glycol (meth) acrylate, n-butoxymethyl acrylamide, i-butoxymethyl acrylamide and the like can be mentioned, and these can be used alone or in admixture of two or more. The amount of the polymerizable monomer having one ethylenically unsaturated group in one molecule used is within a range not exceeding the amount of the crosslinkable monomer (B) constituting the composition of the present invention. Is preferred. When the amount used exceeds the above range, although the flexibility of the resulting cross-linking curable resin composition is improved, the cross-linking density becomes too low and the chemical resistance of the cured product decreases.

The crosslinkable curable resin layer 2 of the present invention comprises
In order to further improve the adhesion to the copper-clad laminate, tetrazole or its derivative may be contained. The addition of tetrazole or its derivative can improve the adhesion to a metal surface by adding a small amount.
-Phenyltetrazole, 5-phenyltetrazole,
5-aminotetrazole, 5-amino-1-methyltetrazole, 5-amino-2-phenyltetrazole, 5
-Mercapto-1-phenyltetrazole, 5-mercapto-1-methyltetrazole and the like can be mentioned, and these can be used alone or in combination.

The amount of tetrazole or its derivative used is in the range of 0.005 to 5 parts by weight based on 100 parts by weight of the total amount of the thermoplastic polymer (A) for binder and the crosslinkable monomer (B). Is preferred. If the amount used is less than 0.005 parts by weight, the adhesion to the copper clad laminate will be insufficient, while if the amount used exceeds 5 parts by weight, it will take a long time to dissolve in the crosslinkable resin composition, In addition, the sensitivity of the cross-linking curable resin layer also decreases.

The cross-linking curable resin layer 2 in the present invention may optionally contain components such as a thermal polymerization inhibitor, a dye, a plasticizer and a filler.

The protective film 3 in the present invention is not particularly limited, but polyethylene which is conventionally used,
A polyolefin film such as polypropylene is preferably used. A protective film having a thickness of 5 to 50 μm is used.

Next, an example of a method for producing the cross-linking curable resin laminate of the present invention will be described. First, a cross-linking curable resin composition comprising the above components (A) to (C) of the present invention is treated with a solvent having a not so high boiling point, for example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, dichloromethane, chloroform, methyl alcohol, One or two of ethyl alcohol, isopropyl alcohol, etc.
Dissolve and mix with more than one seed to form a uniform solution. The amount of these solvents used is 200 parts by weight or less, preferably 50 to 150 parts by weight, based on 100 parts by weight of the crosslinkable curable resin composition.

Next, the solution-type cross-linking curable resin composition is applied onto a supporting film such as polyester by a known method, dried, and a protective film such as polyethylene is stuck on the supporting film and wound into a roll. As a result, the cross-linking curable resin laminate of the present invention can be obtained. Although the thickness of the crosslinkable curable resin layer in the laminate is not particularly limited,
It is in the range of 50 μm.

The cross-linking curable resin laminate of the present invention having the above constitution is used as a dry film resist by laminating it on a copper clad laminate to obtain a printed circuit board or the like.

As a method for laminating the dry film resist on the copper clad laminate, various methods known in the art, for example, a normal pressure hot roll pressure bonding method, a vacuum heat roll pressure bonding method, a vacuum heat press pressure bonding method and the like can be used. You can

When this dry film resist is laminated on a copper-clad laminate, in order to improve the burying property of the resist into scratches and the like on the surface of the copper-clad laminate and to improve the manufacturing yield of printed wiring boards, it is usually performed. Laminate by applying a temperature near 120 ° C. Next, the crosslinking curable resin layer is exposed to form a pattern. As the exposure method, various known methods can be used,
For example, an ultraviolet exposure method, a visible light exposure method, a laser exposure method, or the like can be used, and as a method for selectively performing exposure, a method using a photomask, a direct imaging method, or the like can be used.

Next, the uncured portion (unexposed portion) is removed using an alkali developing solution. As the alkaline developer, for example, sodium carbonate aqueous solution, sodium phosphate aqueous solution, potassium carbonate aqueous solution can be used, and it is also possible to add a small amount of a defoaming agent or a surfactant to these aqueous solutions. Further, a spray method is most commonly used as a removing method, but a part thereof can be replaced by a dipping method.

[0032]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples. The evaluations in the examples were carried out using the methods shown below.

(1) Lamination of Substrate and Measurement of Minimum Development Time The dry film resist from which the protective film has been peeled off is polished on its one-sided copper clad laminate (FR-4, plate thickness 1.6 m).
m, copper thickness 18 μm) was thermally laminated to a copper surface. Lamination was performed using a dry film resist laminator ML-480D manufactured by MCK Co., Ltd., a roll temperature of 120 ° C., a laminating speed of 1.5 m / min, an air cylinder pressure of 1.
It was carried out at 6 kg / cm ² . After standing for 20 minutes after laminating, the polyester support film was peeled off and 1% by weight
The aqueous solution of sodium carbonate was continuously sprayed, and the time for the cross-linking curable resin layer to be completely removed (minimum development time) was measured. The developing conditions at this time are: liquid temperature 30 ° C., spray pressure 1.6 kg / cm ² , distance between spray nozzle and substrate 1
It was 0 cm.

(2) Sensitivity A 25-step step tablet manufactured by Mitsubishi Rayon Co., Ltd. was adhered to the support film of the above laminated product, and an ultra-high pressure mercury lamp (USH-102D manufactured by USHIO INC.) Was used.
Change the exposure time with and expose, peel the support film,
Development was carried out for twice the minimum development time measured above. The exposure time remaining in 15 steps of the step tablet was taken as the sensitivity.

(3) Tent Strength (Development Tenting Property) A substrate (thickness = 1.
400 mm holes of 6 mm and 6 mmφ, double-sided copper-clad laminate) was laminated with each dry film resist under the above conditions, and after exposure with the above 15 exposure levels, the development time was twice the minimum development time. Developed. The development was repeated until all the tents with 400 holes were broken, and the number of times of development in which all the tents were broken was defined as the tent strength.

The abbreviations used in the examples mean the following compounds. (1) MAA: Methacrylic acid (2) St: Styrene (3) MA: Methyl arylate (4) EA: Ethyl acrylate (5) BA: n-Butyl acrylate (6) MMA: Methyl methacrylate (7) Crosslinkable simple Quantity A

[Chemical 1] (8) Crosslinkable monomer B

[Chemical 2] (9) Crosslinkable monomer C

[Chemical 3] (10) BNP: benzophenone (11) MK: Michler's ketone

Synthesis Example of Thermoplastic Polymer Solutions A to J for Binders In a 1000 ml four-necked flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, 140 g of isopropyl alcohol and 1 part of methyl ethyl ketone under a nitrogen atmosphere.
00 g, 0.4 g of azobisisobutyronitrile, and 200 g of monomers of various compositions shown in Table 1 were added, the temperature of the water bath was raised to 80 ° C. with stirring, and polymerization was carried out at that temperature for 2 hours. Then the remaining amount of azobisisobutyronitrile 1.
After 6 g of 6 g was added every 1 hour in 5 batches, the temperature inside the flask was raised to the boiling point of the solvent and polymerization was continued for another 2 hours at that temperature. After that, when the temperature inside the flask became 50 ° C. or lower, 80 g of the remaining amount of isopropyl alcohol was added and the polymerization reaction product was taken out from the flask to obtain thermoplastic polymer solutions A to J shown in Table 1. . The polymerization rate of each polymer was 99.5% or more. Further, the solid content in each polymer solution was 38.7% by weight.

[0038]

[Table 1]

Examples 1 and 2, Comparative Examples 1 to 8 Thermoplastic Coupling Solutions A to J for Binders Obtained in the above Synthesis Examples
Was used to prepare resin solutions having various compositions shown in Table 2.
This prepared composition solution was stirred with a propeller type mixer, and a coating width of 3 μm was applied on a polyester film having a thickness of 20 μm.
The thickness of the cross-linking curable resin composition was 38 μm. Subsequently, a polyethylene protective film having a thickness of 30 μm was laminated on the dried coating film, and both end surfaces were removed by slits to give a width of 250
mm and 120 cm on the ABS resin core with an outer diameter of 10 cm
The roll was wound into a length of m to obtain a dry film resist roll. Table 3 shows the evaluation results of the obtained dry film resist.

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

As described above in detail, the cross-linking curable resin laminate of the present invention has high tent strength (development tenting property). Therefore, the tenting method has the great advantage that fine patterns can be obtained, manufacturing time can be shortened, waste liquid can be reduced, and the like, and an alkali-developing photopolymerizable or radiation-curable dry film resist for printed wiring board production can be achieved. Is extremely useful as

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of a crosslinkable curable resin laminate of the present invention.

[Explanation of symbols]

 1 Support film 2 Crosslinking curable resin layer 3 Protective film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G03F 7/027 502 7/031 H05K 3/06 J H 3/18 D 7511-4E (72) Invention Hiroyuki Otani 20-1 Miyuki-cho, Otake-shi, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Small ▲ Yanagi Seiya 20-1 Miyuki-cho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. A cross-linking curable resin laminate, comprising a cross-linking curable resin layer provided between a support film and a protective film, wherein the cross-linking curable resin layer has 3 to 15 carbon atoms. 15 to 35% by weight of at least one (a-1) of α, β-unsaturated carboxyl group-containing monomers, 5 to 30% by weight of butyl acrylate (a-2), and 1 to 8 carbon atoms. Methacrylic acid ester having alkyl group (a
-3) Thermoplastic polymer for binder (A) composed of 35 to 80% by weight and having a weight average molecular weight in the range of 20,000 to 200,000, and two or more ethylenically unsaturated groups in one molecule. A cross-linkable curable resin laminate comprising a cross-linkable curable resin composition composed of at least one cross-linkable monomer (B) having the above and a photopolymerization initiator (C).