JPH02302403A - Photosensitive polymer composition and photosensitive film using the same composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent heat resistance in soldering under a moisture absorption condition after solder coating, comprising a nongaseous ethylenic unsaturated compound, OH group-containing thermoplastic organic polymer binder, photopolymerization initiator and a specific compound. CONSTITUTION:(A) A nongaseous ethylenic unsaturated compound containing plural C-C double bonds, capable of forming a polymer under irradiation of activation light is blended with (B) a hydroxyl group-containing thermoplastic organic polymer binder (preferably vinyl-based linear polymer compound), (C) a photopolymerization initiator (base) (e.g. 2-ethylanthraquinone) and (D) a compound containing two substituent groups shown by the formula [R is (alkyl) aryl] to give the aimed composition. For example, acrylic acid ester of trimethylolpropane may be cited as the component A. A reaction product of diphenylmethane diisocyanate and methylphenol may be used as the component D.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a photosensitive resin composition and a photosensitive film. More specifically, the present invention relates to a photosensitive resin composition and a photosensitive film used for manufacturing a printed wiring board forming a permanent mask.

[Prior Art] It has been well known in the precision processing industry, for example, in the manufacture of printed wiring boards, that photosensitive resin compositions are used to form resists for plating or etching. Recently, photosensitive resin compositions have also been used in the field of permanent masks such as electroless plating masks and solder masks. The main purpose of a solder mask is to limit the soldering area during soldering, to prevent solder bridging, etc., to prevent corrosion of bare copper conductors, and to maintain electrical insulation between conductors over a long period of time. It is.

Since permanent masks are required to have excellent properties such as heat resistance, solvent resistance, chemical resistance, electrical properties, and mechanical properties, there are a limited number of photosensitive resins that can be used. These resins can be printed on the wiring board as a printing ink or laminated to the wiring board as a so-called photosensitive film, forming a layer of a substantially dry photosensitive resin composition on a support film, or as a so-called liquid resist. After being applied to a wiring board as a coating and drying, it is cured by heating or light irradiation to form a protective coating.

Up until now, many permanent masks such as solder masks have been used (printed masks) whose main component is a thermosetting resin such as epoxy resin or aminoblast resin. However, in recent years, the wiring density of printed wiring boards has increased, and the electrical insulation between conductors has also become stricter, and the permanent masks used for them are also required to be thick and have excellent dimensional accuracy. Therefore, we developed a highly reliable film that uses a photographic method (image is formed by image exposure followed by development), has a thick film (normally 15 μm or more is desired on the conductor), and has excellent dimensional accuracy. It has been desired to develop a photosensitive resin composition that can form a permanent mask.

As such a photosensitive resin composition for forming a permanent mask,
Photosensitive resin composition containing an acrylic polymer, a photopolymerizable monomer, and a photoinitiator as main components (Japanese Patent Application Laid-Open No. 53-5601)
No. 8, Publication No. 54-1018, etc.) are known, but
Such photosensitive resin compositions use a large amount of acrylic polymer to impart film-forming properties, and therefore have the disadvantage that the cured film has insufficient heat resistance.

In order to improve the properties of the cured film, photosensitive resin compositions (Japanese Patent Publication No. 52-37996, Japanese Patent Application Laid-Open No. 58-62636, etc.) are known that use an epoxy resin in combination, but these compositions do not require hardening. Although improvements in film properties are observed, stability is insufficient and long-term storage at room temperature is difficult.

Similarly, photosensitive resin compositions using aldehyde condensation resin precursors (JP-A-48-73148 and JP-A-58-420)
40, etc.) and photosensitive resin compositions using binder polymers having thermosetting groups (Japanese Patent Publication No. 52-4)
3090) is also known.

Recently, printed wiring boards formed with copper patterns are mounted after being coated with a permanent mask resist, and the soldering parts are pre-coated with solder using a hot air leveler device before component mounting.

For mounting, chip components and surface mount components in the form of flat packages are soldered using infrared reflow or adhesive flow in the vapor phase (abbreviated as VPS), and then insert-type components are soldered in a conventional molten solder bath. It is done as follows.

As shown in these processes, permanent masks are increasingly required to have high heat resistance.

In particular, air leveler soldering and flow soldering are sometimes prone to scratches caused by jigs, and strength at high temperatures is also required.

In this case, soldering is performed two or three times, and the resist that has been exposed to carbon heat may be stored for a long period of time until it is mounted, and during this time it absorbs moisture, sometimes causing problems such as blistering during mounting soldering. There is.

[Problem to be solved by the invention]

The present invention solves the above-mentioned drawbacks of the prior art, and provides a photosensitive resin composition that improves heat resistance during soldering after being soldered and stored under moisture absorption, and improves storage stability as a composition. The present invention provides a product and a photosensitive film using the same.

[Means for Solving the Problems] The present invention provides (a) a non-gaseous ethylenically unsaturated compound having at least two carbon-carbon double bonds and capable of forming a polymer upon irradiation with actinic light; b) a thermoplastic organic polymer binder having hydroxyl groups; (c) a photoinitiator or photoinitiator system that can be activated by actinic light; and (d) a compound of the general formula (I) ll -N-C0-R(I ) (wherein R represents an aryl group or an alkylaryl group) The present invention relates to a photosensitive resin composition containing a compound having at least two substituents represented by the formula (wherein R represents an aryl group or an alkylaryl group), and a photosensitive film using the composition.

Next, the photosensitive resin composition of the present invention will be explained in detail.

The photosensitive resin composition of the present invention contains as an essential component (a) a non-gaseous ethylenically unsaturated compound having at least two carbon-carbon double bonds and capable of forming a polymer upon irradiation with actinic light. do. This compound is already a known compound, and examples include the photopolymerizable compound disclosed in Japanese Patent Publication No. 53-37214, and the photopolymerizable compound disclosed in Japanese Patent Publication No. 53-560.
Monomer described in Publication No. 18, Japanese Patent Publication No. 59-23
Examples include photopolymerizable urethane compounds described in Japanese Patent No. 723.

Examples of this compound include trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythrinth, 1,6-hexanediol, propylene glycol, tetraethylene glycol, dibromneopentyl glycol, lauryl alcohol, etc. Mention may be made of acrylic esters or methacrylic esters of hydrohydric or polyhydric alcohols. Furthermore, reaction products of acrylic acid or methacrylic acid with compounds having an epoxy group such as cycloaliphatic epoxy resins, epoxidized novolac resins, and bisphenol A-epichlorohydrin epoxy resins may also be used.

The content of the non-gaseous ethylenically unsaturated compound having at least two carbon-carbon double bonds and capable of forming a polymer upon irradiation with actinic light in the photosensitive resin composition is determined by 20 to 8 in the composition in terms of viscosity and photocurability
0% by weight is preferred.

The photosensitive resin composition of the present invention contains (b) a thermoplastic organic polymer binder as an essential component.

As this thermoplastic organic polymer binder, already known compounds are used, examples of which include Japanese Patent Publication No. 41-1
Examples include thermoplastic polymers described in Japanese Patent No. 5932, but vinyl-based linear polymers are preferred from the viewpoint of compatibility with other components, adhesion to the surface of the substrate to which they are applied, and the like.

Various vinyl monomers can be used as the polymerization component of the vinyl linear polymer compound. Suitable examples of vinyl monomers include styrene and α-methylstyrene, styrene derivatives such as vinyltoluene, acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, ethyl acrylate, 2-hydroxyethyl meccrylate. , 2-hydroxypropyl acrylate, trifluoroethyl methacrylate, tetrafluoropropyl acrylate, L-butylaminoethyl methacrylate, 2,
3-dibromopropyl methacrylate, 3-chloro-2
Examples include derivatives of acrylic acid or methacrylic acid such as -hydroxypropyl methacrylate, tetrahydrofurfuryl methacrylate, tribromophenyl acrylate, acrylamide, acrylonitrile, and compounds having two double bonds such as butadiene. These can be used alone or in combination of two or more.

The content of the thermoplastic organic polymer binder in the photosensitive resin composition is preferably 20 to 80% by weight in the composition from the viewpoint of viscosity and photocurability of the photosensitive resin composition.

The photosensitive resin composition of the present invention contains as an essential component (c) a photopolymerization initiator or photopolymerization initiator system that can be activated by actinic light and initiates the polymerization of the unsaturated compound.

Examples of photopolymerization initiators that can be used include 2-ethylanthraquinone, 2-1-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2.
Substituted or unsubstituted polynuclear quinones such as 3-diphenylanthraquinone, diketones such as diacetyl and hensyl, α-ketaldonyl alcohols and ethers such as benzoin and pivalone, α-phenylhenzoin, α, α-di Examples include α-hydrocarbon-substituted aromatic acyloins such as ethoxyacetophenone, aromatic ketones such as benzophenone, and 4,4′-bisdialkylaminobenzophenone, and these may be used alone or in combination of two or more types. . Photopolymerization initiator systems that can be used include 2, 4.
5-1-Rearyl imidazole dimer and 2-mercaptobenzoquinazole, leuco crystal violet,
Tris (4-T diethylamino-2-methylphenyl)
Examples include combinations with methane and the like. Further, additives can be used which do not have photoinitiating properties by themselves, but which, when used in combination with the above-mentioned substances, result in a photopolymerization initiator system with better photoinitiating performance as a whole. Examples include tertiary amines such as triethanolamine for benzophenone.

The photosensitive resin composition of the present invention has the general formula (d) (wherein R
represents an aryl group or an alkylaryl group] as an essential component.

Compounds that can be used include trifunctional isocyanate compounds such as toluylene diisocyanate, naphthylene-1,5-diisocyanate, 0-toluylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and xylylene diisocyanate; There are compounds obtained by reacting trifunctional isocyanate compounds such as triphenylmethane triisocyanate with aromatic alcohols such as methylphenol and dimethylphenol. These compounds are generally collectively referred to as blocked isocyanates. Further, a blocked isocyanate compound obtained by reacting an aromatic alcohol with a reaction product of trimethylolpropane and an isocyanate group of toluylene diisocyanate or diphenylmethane diisocyanate may also be used.

These blocked isocyanate compounds include Coronate AP Stable, Millionate MS-50, Coronate 2503 (manufactured by Nippon Polyurethane Co., Ltd., trade name), DeModule AP Stable, DeModule CP Stable, etc. (manufactured by Nippon Polyurethane Co., Ltd.), etc. (manufactured by Hoechst, trade name), Acitol VX81, etc. (manufactured by Hoechst, trade name).

(d) The compound having at least two or more substituents represented by general formula (I) regenerates isocyanate groups by heating, and immediately reacts with the hydroxyl group of the binder to crosslink, thereby improving the heat resistance of the resulting permanent mask. It is thought to improve sex.

The content of (d) a compound having at least two substituents represented by the general formula (+) in the photosensitive resin composition is determined by the viscosity, developability, heat resistance, etc. of the photosensitive resin composition, and the curing properties. From the viewpoint of coating properties, the amount is preferably 5 to 50% by weight in the composition. From the viewpoint of heat resistance, the content is more preferably 8 to 20% by weight.

Furthermore, the photosensitive resin composition of the present invention can contain other subsidiary components. Secondary components include thermal polymerization inhibitors, dyes, pigments, particulate fillers, coatability improvers, flame retardants, flame retardant aids, etc., and these selections are based on those of ordinary photosensitive resin compositions. This will be done based on the same considerations.

The photosensitive resin composition of the present invention can be applied directly onto a substrate to be processed and protected by conventional methods such as dip coating, flow coating, and screen printing to easily form a photosensitive layer with a thickness of 10 to 150 μm. can be formed. For coating,
If necessary, the composition can be dissolved in a solvent. Examples of the solvent include methyl ethyl ketone, propylene glycol methyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, cyclohexanone, methyl cellosolve, methylene chloride, 1.1.1-
Trichloroethane and the like can be mentioned.

Further, the above photosensitive resin composition is used as a so-called photosensitive film in which a layer thereof is formed on a support film.

The present invention also relates to a photosensitive film having a layer of the photosensitive resin composition of the present invention on a support film.

The support film used in the present invention may be transparent or opaque to actinic light.

Preferred examples include known films such as polyester film, polyimide film, and polystyrene film.

A photosensitive film can be created as follows.

Formation of a layer of the photosensitive resin composition on the support film is as follows:
This can be done by a conventional method. For example, a photosensitive resin composition is uniformly dissolved in an organic solvent such as methyl ethyl ketone, toluene, or methylene chloride (however, materials that do not dissolve, such as flame retardant antimony trioxide, pigments, etc., are uniformly dispersed), and this solution is The coating is applied onto the support film by a knife coating method, a roll coating method, etc., and then dried.

When producing a long photosensitive film, the photosensitive film is wound onto a roll at the final stage of production. In this case, by using a backside-treated support film using a known method employed in the production of pressure-sensitive adhesive tapes, etc., a support film for the photosensitive resin composition layer when wound into a roll can be used. It is possible to prevent the film from being transferred to the back surface. For the same purpose, such as preventing dust from adhering, it is preferable to laminate a removable cover film on the layer of the photosensitive resin composition.

Examples of removable cover films include polyethylene film, polypropylene film, Teflon film, and surface-treated paper. It is sufficient that the adhesive force between the layer of the photosensitive resin composition and the cover film is smaller.

The thickness of the layer of the photosensitive resin composition of the photosensitive film made of the photosensitive resin composition of the present invention is determined in order to maintain a high degree of electrical insulation between the conductors of the printed wiring board to which it is applied. 20 to 200 in terms of resolution of solder mask pattern
Preferably it is μm.

Next, an example of how to use the photosensitive film will be explained. Lamination of the photosensitive film onto the substrate is easy. That is, if there is no cover film, the photosensitive resin composition layer of the photosensitive element is placed on the substrate side, and the photosensitive resin composition layer of the photosensitive element is laminated under heat and pressure. The heating and pressurizing lamination can be carried out using Lamination+, which is well known in printed wiring board manufacturers.

When the substrate has irregularities of 10 μm or more, such as a printed wiring board on which conductive wiring lines are formed, it is preferable to laminate under reduced pressure or vacuum.

As the laminating apparatus, there are apparatuses described in Japanese Patent Application Laid-Open No. 52-52703, Japanese Patent Publication No. 55-13341, and the like.

Next, the process after coating the photosensitive resin composition on the substrate or the process after laminating it as a photosensitive film will be explained. Exposure and development can be carried out by conventional methods. When the support film of the photosensitive film is opaque to actinic light, the support film is peeled off and imagewise exposed through a negative mask using a light source such as a high-pressure mercury lamp or an ultra-high-pressure mercury lamp. Although heat treatment at 50° C. to 100° C. before and after exposure is preferred in order to improve the adhesion between the substrate and the photosensitive resin layer, the heat treatment may not be performed.

Development can be carried out using an alkaline aqueous solution such as a 1% aqueous sodium carbonate solution or an organic solvent such as 1,1.1-1-lichloroethane.

After development, heat treatment at 120° C. to 200° C. and exposure to active light result in a solder mask with excellent properties. In particular, heat treatment is important for advancing the reaction between the compound represented by the general formula ([) and the thermoplastic organic polymer binder having a hydroxyl group. The processing time is
It is preferable to heat the film at 120"C for about 1 hour or more, and at 150"C for about 30 minutes or more.The heat treatment after development and the exposure to active light can be performed in any order, and each can be divided into several steps. The protective film obtained by heat treatment after development and exposure to active light exhibits excellent soldering heat resistance.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

In addition, "parts" in the examples indicate "parts by weight" unless otherwise specified.

Examples 1 to 4 and Comparative Examples 5 to 6 Trimethylhexamethylene diisocyanate/1°4-
Reactant of cyclohexane dimetatool/2-hydroxyethyl acrylate (I6:5:8 weight ratio)
57 part benzophenone
4 parts 4.4'-diethylaminobenzophenone 0.2 parts P-methoxyphenol
0.1 part Victoria Pure Blue
0.05 part 5-amino-1,3,4-thiadiazole-
2-thiol 0.3
Parts antimony trioxide 2.0 parts propylene glycol monomethyl ether 30 parts methyl ethyl ketone 70 parts were uniformly dissolved in a solution in which the following compounds were respectively added to obtain photosensitive resin compositions (1) to (2).

■Millionate MS-50 (methylphenol reaction product of diphenylmethane diisocyanate, manufactured by Nippon Polyurethane Industries ■, trade name) 10 parts■ Same as above
20 parts■Coronate 2503 () Limethylolpropane, diphenylmethane diisocyanate and methylphenol reactant, Nippon Polyurethane Industries■
(product name) 15 parts ■Coronate AP Stable (trimethylolpropane, a reaction product of toluylene diisocyanate and phenol,
Manufactured by Nippon Polyurethane Industries, product name)
15 parts ■No additives.

■Epicote 828 (diphenylpropane diglycidyl ether epoxy resin, manufactured by Shell Chemical ■, product name)
10 parts Solutions of photosensitive resin compositions (1) to (2) were prepared using the above formulations. Each of these solutions was applied onto a polyethylene terephthalate film with a thickness of 20 μm, and then dried (80-110″C1 for about 10 minutes) to form a photosensitive layer with a thickness of 75 μm. A long photosensitive film was obtained by performing this process continuously.Then, while peeling off the polyethylene film, the resist layer surface was pretreated with a commercially available laminating device to clean the copper surface. Laminated board (manufactured by Hitachi Chemical, MCL-
E61 copper foil thickness 35 μm, board thickness 1.6 am
) layered on top.

Next, pass through the negative mask to make 201B manufactured by Oak Seisakusho.
Exposure was performed at 250 mJ/cJ using a mold exposure machine. After being left at room temperature for 30 minutes, spray development was performed at 30°C for 200 seconds using a 1% aqueous sodium carbonate solution. Then,
Toshiba ultraviolet irradiation equipment manufactured by Toshiba Denzai (rated voltage 200V,
Rated power consumption cuff, 2kW.

Using a compatible lamp (H5600L/2, 1 lamp), 3 J/a! After irradiation at 150°C
A solder mask with excellent dimensional accuracy corresponding to a negative mask was obtained by heat treatment for 0 minutes.

The following tests were conducted on the photosensitive films obtained in the above Examples and Comparative Examples.

Solder coating resistance Water-soluble flux W-1 is applied on top of the above solder mask.
35M (trade name of flux made by Metku) and solder coated (at 245° C. for 15 seconds) with a solder coater H3C-224-Dn (hot air leveler system name made by Dainippon Screen Manufacturing Co., Ltd.). Next, wash the board with hot water,
Dropped Fluffkus. The solder coating resistance of the solder coated board was observed and the results are shown in Table 1.

Evaluation was performed according to the following criteria.

O...No abnormality ×...Solder mask has abnormality such as blistering Solder heat resistance after moisture absorption Solder coated board under constant temperature (45°C 195%)
) for 96 hours. Then, immediately use rosin-based flux MH-820V (manufactured by Tamura Kaken ■) for 26 hours.
Solder at 0°C for 10 seconds, 1. l, 1-1-
After cleaning with dichloroethane, the board was observed for solder heat resistance after moisture absorption, and the results are shown in Table 1.

Evaluation was performed according to the following criteria.

○... No abnormalities ×... Abnormalities such as blistering in the solder mask Developability test The photosensitive film obtained in the above example was placed in a thermostatic oven (40°C).
) for 10 days, then peel off the polyethylene film and use a commercially available laminating machine to clean the copper surface by pre-treating the resist layer surface (manufactured by Hitachi Chemical Co., Ltd., MC).
L-E61. Copper foil thickness 35 μm, board thickness 1.6
mm).

This substrate was heated at 30° using a 1% sodium carbonate aqueous solution.
Spray development was carried out at C for 200 seconds. The suitability of development (developability) was observed. Those that cannot be developed are considered to have been crosslinked during storage. The results are summarized in Table 1.

○...developing tube, ×...unable to develop Table 1 [Effects of the invention] The photosensitive resin composition of the present invention has storage stability and can be easily soldered under moisture absorption conditions after being coated with solder. However, it has excellent heat resistance. The photosensitive resin composition of the present invention is suitable for permanent masks and photosensitive films for printed wiring boards.

Claims (4)

[Claims] 1. (a) a non-gaseous ethylenically unsaturated compound having at least two carbon-carbon double bonds and capable of forming a polymer upon irradiation with actinic light; (b) a thermoplastic organic polymer binder having a hydroxyl group; (c) Photopolymerization initiator or photopolymerization initiator system that can be activated by active light and (d) General formula (I) ▲ Numerical formulas, chemical formulas, tables, etc. are included ▼ [In the formula, R is an aryl group or an alkylaryl group A photosensitive resin composition comprising a compound having at least two substituents represented by the following formula. 2. 2. The photosensitive resin composition according to claim 1, wherein the compound having at least two or more substituents represented by general formula (I) accounts for 5 to 30% by weight of the composition. 3. 3. The photosensitive resin composition according to claim 1, wherein the compound having at least two substituents represented by general formula (I) is a blocked isocyanate compound. 4. A photosensitive film comprising a layer of the photosensitive resin composition according to claim 1 on a support film.