JP2014228665A - Method for manufacturing flexible printed wiring board and flexible printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a flexible printed wiring board, by which an insulating film for a flexible printed wiring board excellent in reliability in shock resistance, flexibility and warpage resistance as well as in process accuracy can be collectively formed with good workability.SOLUTION: The method for manufacturing a flexible printed wiring board includes steps of: forming at least one layer of a resin layer (A) comprising an alkali development type photosensitive resin composition (A1) on a flexible printed wiring board; forming at least one layer of a resin layer (B) comprising a photosensitive thermosetting resin composition (B1) containing an alkali-soluble resin having an imide ring, a photo-base generator and a heat-reactive compound on the resin layer (A); irradiating the resin layers (A) and (B) formed in the above-described steps with light along a pattern; heating the resin layers (A) and (B) irradiated with light in the above-described step; and forming a coverlay or the like by subjecting the resin layers (A) and (B) irradiated with light to alkali development.

Description

  The present invention relates to a method for manufacturing a flexible printed wiring board and a flexible printed wiring board.

  In recent years, it has become necessary to reduce the space of circuit boards due to the small size and thinness of electronic devices due to the spread of smartphones and tablet terminals. Therefore, the use of the flexible printed wiring board which can be folded and accommodated is expanded, and the reliability with respect to such a flexible printed wiring board is required to be higher than ever.

  On the other hand, as an insulating film to ensure the insulation reliability of flexible printed wiring boards, a cover based on polyimide with excellent mechanical properties such as heat resistance and flexibility is used for the bent part (bent part). Lay is used (for example, see Patent Documents 1 and 2), and the mounting part (non-bent part) uses a photosensitive resin composition that is excellent in electrical insulation and solder heat resistance and can be finely processed. The process is widely adopted.

  That is, a polyimide-based coverlay having excellent mechanical properties such as heat resistance and flexibility is not suitable for fine wiring because it requires processing by die punching. Therefore, it is necessary to partially use an alkali developing type photosensitive resin composition (solder resist) that can be processed by photolithography in a chip mounting portion that requires fine wiring.

Japanese Patent Laid-Open No. Sho 62-26392 Japanese Unexamined Patent Publication No. 63-110224

  Thus, in the manufacturing process of a flexible printed wiring board, there was a problem that it was inferior in cost and workability because it was necessary to employ a mixed mounting process of a process of bonding a cover lay and a process of forming a solder resist.

  Conventionally, it has been proposed to apply an insulating film as a solder resist as a coverlay of a flexible printed wiring board for such a mixed mounting process. However, such a resin composition for a solder resist has insufficient reliability such as impact resistance and flexibility as a cover lay, and a process for collectively forming a bent portion (bent portion) and a mounting portion (non-bent portion). Has not yet been put to practical use. In addition, since the resin composition for solder resist is accompanied by curing shrinkage due to acrylic photopolymerization, there is a problem in dimensional stability such as warping of a flexible wiring board.

  On the other hand, as a photosensitive polyimide capable of achieving both alkali solubility and mechanical properties, a method of thermally ring-closing after patterning using a polyimide precursor has been proposed. However, problems remain in the workability of wiring board manufacture, such as requiring high-temperature treatment, and it has not yet been put into practical use.

  It is also conceivable to apply an insulating film as a coverlay as a solder resist for a flexible printed wiring board. However, such a coverlay film requires a complicated process for pattern formation, and has a low processing accuracy such as punching due to punching, and supports the formation of a fine pattern due to resin oozing during thermocompression bonding. There was a problem that it was difficult.

  Accordingly, an object of the present invention is to provide an insulating film for a flexible printed wiring board having excellent reliability and processing accuracy such as impact resistance, flexibility, and low warpage, particularly a bent portion (bending portion) and a mounting portion (non-bending portion). A flexible printed wiring board manufacturing method and a flexible printed wiring board capable of forming collectively an insulating film, for example, a coverlay and a solder resist.

As a result of intensive research aimed at realizing the above object, the inventors have completed the present invention having the following contents.
That is, in the method for producing a flexible printed wiring board of the present invention, the step of forming at least one resin layer (A) made of an alkali-developable photosensitive resin composition (A1) on the flexible printed wiring board, the resin layer ( A) A step of forming at least one resin layer (B) composed of a photosensitive thermosetting resin composition (B1) containing an alkali-soluble resin having an imide ring, a photobase generator, and a heat-reactive compound. , A step of irradiating the resin layers (A) and (B) formed in the step with light in a pattern, a step of heating the resin layers (A) and (B) irradiated with the light in the step, and A step of alkali-developing the light-irradiated resin layers (A) and (B) to form at least one of a coverlay and a solder resist.

  The flexible printed wiring board of the present invention is manufactured by the above manufacturing method.

  According to the present invention, an insulating film for a flexible printed wiring board having excellent reliability and processing accuracy such as impact resistance, flexibility, and low warpage, particularly a bent portion (bent portion) and a mounting portion (non-bent portion). ), A method for producing a flexible printed wiring board capable of forming a cover lay and a solder resist, for example, with good workability, and a flexible printed wiring board can be provided.

It is process drawing which shows an example of the manufacturing method of the flexible printed wiring board of this invention.

  The method for producing a flexible printed wiring board of the present invention includes a step of forming at least one resin layer (A) made of an alkali-developable photosensitive resin composition (A1) on the flexible printed wiring board, the resin layer (A) A step of forming at least one resin layer (B) comprising a photosensitive thermosetting resin composition (B1) containing an alkali-soluble resin having an imide ring, a photobase generator, and a thermoreactive compound; A step of irradiating the resin layers (A) and (B) formed in the step with light in a pattern, a step of heating the resin layers (A) and (B) irradiated with the light in the step, and the light A step of alkali-developing the irradiated resin layers (A) and (B) to form at least one of a coverlay and a solder resist.

In the present invention, in the resin layer (B), (1) a resin having an imide ring in the molecule is used, and (2) a composition that causes an addition reaction between an alkali-soluble resin and a thermally reactive compound is used. Thus, the resin layer (B) can function as a reinforcing layer.
That is, by forming a resin layer (A) made of a conventional solder resist composition and laminating the resin layer (B) on the resin layer (A), impact resistance, flexibility, low warpage, etc. A cover lay and a solder resist having excellent reliability and processing accuracy can be collectively formed on a flexible printed wiring board. Note that an interlayer insulating film may be formed as the insulating film.

Hereinafter, an example of the manufacturing method of the flexible printed wiring board of this invention is demonstrated based on FIG.
[Formation step of resin layer (A)]
In this step, at least one resin layer (A) made of the alkali development type photosensitive resin composition (A1) is formed on the flexible printed wiring board. Since the resin layer (A) can be alkali-developed, a pattern can be formed. Further, by laminating the resin layer (A), the circuit followability and the adhesion to the substrate can be improved.
The flexible printed wiring board is obtained by forming a copper circuit 2 on a flexible substrate 1. The position where the resin layer (A) is formed may be one of a bent portion and a non-bent portion, but is preferably both a bent portion and a non-bent portion. The bent portion is a portion that is repeatedly bent and requires flexibility, and the non-bent portion is a portion that is not bent, such as a chip mounting portion.

Examples of the method for forming the resin layer (A) include a coating method and a laminating method.
In the case of the coating method, the alkali-developable photosensitive resin composition (A1) is coated on a flexible printed wiring board by a method such as a screen printing method, a curtain coating method, a spray coating method, or a roll coating method, and 50 to 130 ° C. The resin layer (A) is formed by heating at a temperature of about 15 to 60 minutes.
In the case of the laminating method, first, the alkali developing type photosensitive resin composition (A1) is diluted with an organic solvent to adjust to an appropriate viscosity, applied onto a carrier film and dried to have a resin layer (A). Create Next, after bonding together so that a resin layer (A) may contact a flexible printed wiring board with a laminator etc., a carrier film is peeled.

[Formation step of resin layer (B)]
In this step, a resin layer (B) comprising a photosensitive thermosetting resin composition (B1) containing an alkali-soluble resin having an imide ring, a photobase generator, and a heat-reactive compound on the resin layer (A). ) At least one layer. Since the resin layer (B) can be alkali-developed, a fine pattern can be formed and the processing accuracy is excellent. Further, by laminating the resin layer (B), it is possible to improve impact resistance, flexibility and low warpage.
The position where the resin layer (B) is formed is preferably both a bent portion and a non-bent portion on the resin layer (A). However, the resin layer (B) may be formed only on the bent portion or only on the non-bent portion of the resin layer (A).
Further, a further layer may be interposed between the resin layer (B) and the resin layer (A).
The resin layer (B) can be formed by the same method as the method for forming the resin layer (A).
The resin layers (A) and (B) may be formed by laminating the laminated dry film on a flexible printed wiring board after making them into one laminated dry film.
In the present invention, the resin layer (A) is preferably formed thicker than the resin layer (B) from the viewpoint of followability to the copper circuit.

[Light irradiation process]
In this step, the resin layers (A) and (B) are irradiated with light in a negative pattern. By this step, the photobase generator contained in the photosensitive thermosetting resin composition can be activated to cure the light irradiation part.
As a light irradiation device, a direct drawing device (for example, a laser direct imaging device that directly draws an image with a laser using CAD data from a computer), a light irradiation device equipped with a metal halide lamp, or a light irradiation device equipped with a (ultra) high pressure mercury lamp. In addition, a light irradiator equipped with a mercury short arc lamp or a direct drawing apparatus using an ultraviolet lamp such as a (super) high pressure mercury lamp can be used.

As the active energy ray used for light irradiation, it is preferable to use laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm. Moreover, the light irradiation amount varies depending on the film thickness, etc., generally 50~1500mJ / cm ^2, preferably be in the range of 100~1000mJ / cm ^2.

[Heating process]
In this step, the resin layers (A) and (B) are heated. Thereby, it can fully harden | cure to a deep part with the base generate | occur | produced by light irradiation. This process is a so-called PEB (POST EXPOSURE BAKE) process.
The heating temperature is, for example, 80 to 140 ° C. By setting the heating temperature to 80 ° C. or higher, the light irradiation part can be sufficiently cured. On the other hand, by setting the heating temperature to 140 ° C. or lower, only the light irradiation part can be selectively cured. The heating time is, for example, 10 to 100 minutes. In the unirradiated portion, no base is generated from the photobase generator, so that thermosetting is suppressed.

[Development process]
In this step, the resin layers (A) and (B) irradiated with light are developed to form at least one of a coverlay and a solder resist. By this development, a patterned coverlay and solder resist can be obtained in a lump.
The development method is alkali development, and can be performed by a known method such as a dipping method, a shower method, a spray method, or a brush method.
Examples of the alkaline developer include potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, ethanolamine, amines such as imidazole, tetramethylammonium hydroxide aqueous solution (TMAH), etc. An alkaline aqueous solution or a mixed solution thereof can be used.

[Other processes]
In the present invention, the following steps may be added as necessary.
(Second light irradiation process)
After the development step, the resin layers (A) and (B) may be irradiated with light. By this light irradiation, the photobase generator remaining without being activated in the resin layer (B) in the previous light irradiation step is activated to sufficiently generate a base.
The wavelength of ultraviolet rays and the light irradiation amount (exposure amount) in this light irradiation may be the same as or different from those in the light irradiation step. The light irradiation amount is, for example, 150 to 2000 mJ / cm ² .

(Thermosetting process)
Further, after the development step, the resin layers (A) and (B) may be further thermally cured (post-cured) by heating. By thermosetting, the resin layers (A) and (B) can be sufficiently thermoset. The heating temperature is, for example, 150 ° C. or higher.

[Alkali development type photosensitive resin composition used for resin layer (A)]
The alkali-developable photosensitive resin composition constituting the resin layer (A) contains a resin that contains one or more functional groups among phenolic hydroxyl groups, thiol groups, and carboxyl groups and that can be developed with an alkaline solution. It is sufficient to use a photocurable resin composition or a thermosetting resin composition. Preferred examples include a resin composition containing a compound having two or more phenolic hydroxyl groups, a carboxyl group-containing resin, a compound having a phenolic hydroxyl group and a carboxyl group, and a compound having two or more thiol groups. It is done.

  For example, a light containing a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin, a compound having an ethylenically unsaturated bond, a photopolymerization initiator, and a heat-reactive compound conventionally used as a solder resist composition A curable thermosetting resin composition is mentioned.

  Here, as the carboxyl group-containing resin or the carboxyl group-containing photosensitive resin, the compound having an ethylenically unsaturated bond, the photopolymerization initiator, and the heat-reactive compound, known and commonly used ones are used.

[Photosensitive thermosetting resin composition used for resin layer (B)]
(Alkali-soluble resin having an imide ring)
In the present invention, the alkali-soluble resin having an imide ring has an alkali-soluble group such as a carboxyl group and an acid anhydride group and an imide ring. For introducing the imide ring into the alkali-soluble resin, a known and usual method can be used. For example, the resin obtained by making a carboxylic anhydride component react with an amine component and / or an isocyanate component is mentioned. The imidization may be performed by thermal imidization or chemical imidization, and these can be used in combination.

  Here, examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydrides and tricarboxylic acid anhydrides, but are not limited to these acid anhydrides, and acid anhydrides that react with amino groups or isocyanate groups. Any compound having a physical group and a carboxyl group can be used, including derivatives thereof. These carboxylic anhydride components may be used alone or in combination.

  Examples of the tetracarboxylic acid anhydride include pyromellitic dianhydride, 3-fluoropyromellitic dianhydride, 3,6-difluoropyromellitic dianhydride, 3,6-bis (trifluoromethyl) pyro Merit acid dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic acid Anhydride, 2,2′-difluoro-3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5,5′-difluoro-3,3 ′, 4,4′-biphenyltetracarboxylic acid Anhydride, 6,6′-difluoro-3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 5,5 ′, 6,6′-hexafluoro-3,3 ′ , 4,4'-biphenyltet Carboxylic dianhydride, 2,2′-bis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5,5′-bis (trifluoromethyl) -3, 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 6,6′-bis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′ , 5,5′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 6,6′-tetrakis (trifluoromethyl) -3, 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 5,5 ′, 6,6′-tetrakis (trifluoromethyl) -3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride , And 2,2 ', 5,5', 6,6 -Hexakis (trifluoromethyl) -3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3 ", 4,4 "-Terphenyltetracarboxylic dianhydride, 3,3 '", 4,4' "-quaterphenyltetracarboxylic dianhydride, 3,3" ", 4,4" "-kinkphenyltetracarboxylic acid Dianhydride, methylene-4,4′-diphthalic dianhydride, 1,1-ethynylidene-4,4′-diphthalic dianhydride, 2,2-propylidene-4,4′-diphthalic dianhydride 1,2-ethylene-4,4′-diphthalic dianhydride, 1,3-trimethylene-4,4′-diphthalic dianhydride, 1,4-tetramethylene-4,4′-diphthalic acid Anhydride, 1,5-pentamethylene-4,4'-diph Talic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, difluoromethylene-4,4′-diphthal Acid dianhydride, 1,1,2,2-tetrafluoro-1,2-ethylene-4,4′-diphthalic dianhydride, 1,1,2,2,3,3-hexafluoro-1, 3-trimethylene-4,4′-diphthalic dianhydride, 1,1,2,2,3,3,4,4-octafluoro-1,4-tetramethylene-4,4′-diphthalic dianhydride 1,1,2,2,3,3,4,4,5,5-decafluoro-1,5-pentamethylene-4,4′-diphthalic dianhydride, thio-4,4′- Diphthalic dianhydride, sulfonyl-4,4′-diphthalic dianhydride, 1,3-bis (3,4-dicarboxyphene) ) -1,1,3,3-tetramethylsiloxane dianhydride, 1,3-bis (3,4-dicarboxyphenyl) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenyl) ) Benzene dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,3-bis [ 2- (3,4-Dicarboxyphenyl) -2-propyl] benzene dianhydride, 1,4-bis [2- (3,4-dicarboxyphenyl) -2-propyl] benzene dianhydride, bis [ 3- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, bis [4- (3,4-dicarboxyphenoxy) phenyl] methane dianhydride, 2,2-bis [3- (3,4- Dicarboxyphenoxy Phenyl] propane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 2,2-bis [3- (3,4-dicarboxyphenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, bis (3,4- Dicarboxyphenoxy) dimethylsilane dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) -1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic Acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid Anhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3 ′ , 4,4′-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, methylene-4,4′-bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethynylidene-4,4′-bis (cyclohexane) San-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1,1,3,3,3 -Hexafluoro-2,2-propylidene-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride Thio-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4′-bis (cyclohexane-1,2-dicarboxylic acid) dianhydride, 3,3 ′ -Difluorooxy-4,4'-diphthalic dianhydride, 5,5'-difluorooxy-4,4'-diphthalic dianhydride, 6,6'-difluorooxy-4,4'-diphthalic acid Anhydride, 3, 3 ', 5, 5', 6 6′-hexafluorooxy-4,4′-diphthalic dianhydride, 3,3′-bis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 5,5′-bis (tri Fluoromethyl) oxy-4,4′-diphthalic dianhydride, 6,6′-bis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 3,3 ′, 5,5′- Tetrakis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 3,3 ′, 6,6′-tetrakis (trifluoromethyl) oxy-4,4′-diphthalic dianhydride, 5, 5 ', 6,6'-tetrakis (trifluoromethyl) oxy-4,4'-diphthalic dianhydride, 3,3', 5,5 ', 6,6'-hexakis (trifluoromethyl) oxy- 4,4'-diphthalic dianhydride, 3,3'-diflu Orosulfonyl-4,4′-diphthalic dianhydride, 5,5′-difluorosulfonyl-4,4′-diphthalic dianhydride, 6,6′-difluorosulfonyl-4,4′-diphthalic dianhydride 3,3 ′, 5,5 ′, 6,6′-hexafluorosulfonyl-4,4′-diphthalic dianhydride, 3,3′-bis (trifluoromethyl) sulfonyl-4,4′- Diphthalic dianhydride, 5,5′-bis (trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 6,6′-bis (trifluoromethyl) sulfonyl-4,4′-diphthalic acid Dianhydride, 3,3 ′, 5,5′-tetrakis (trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 3,3 ′, 6,6′-tetrakis (trifluoromethyl) sulfonyl -4,4'-diphthalate Dianhydride, 5,5 ′, 6,6′-tetrakis (trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 3,3 ′, 5,5 ′, 6,6′-hexakis ( Trifluoromethyl) sulfonyl-4,4′-diphthalic dianhydride, 3,3′-difluoro-2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 5,5′-difluoro -2,2-perfluoropropylidene-4,4'-diphthalic dianhydride, 6,6'-difluoro-2,2-perfluoropropylidene-4,4'-diphthalic dianhydride, 3, 3 ′, 5,5 ′, 6,6′-hexafluoro-2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 3,3′-bis (trifluoromethyl) -2, 2-perfluoropropylidene-4,4'-diphthalate Acid dianhydride, 5,5′-bis (trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 6,6′-difluoro-2,2-perfluoro Propylidene-4,4′-diphthalic dianhydride, 3,3 ′, 5,5′-tetrakis (trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride 3,3 ′, 6,6′-tetrakis (trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 5,5 ′, 6,6′-tetrakis ( Trifluoromethyl) -2,2-perfluoropropylidene-4,4′-diphthalic dianhydride, 3,3 ′, 5,5 ′, 6,6′-hexakis (trifluoromethyl) -2,2 -Perfluoropropylidene-4,4'-diph Talic dianhydride, 9-phenyl-9- (trifluoromethyl) xanthene-2,3,6,7-tetracarboxylic dianhydride, 9,9-bis (trifluoromethyl) xanthene-2,3 6,7-tetracarboxylic dianhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 9,9-bis [4- (3 , 4-Dicarboxy) phenyl] fluorene dianhydride, 9,9-bis [4- (2,3-dicarboxy) phenyl] fluorene dianhydride, ethylene glycol bistrimellitic dianhydride, 1,2- ( Ethylene) bis (trimellitic anhydride), 1,3- (trimethylene) bis (trimellitic anhydride), 1,4- (tetramethylene) bis (trimellitic anhydride), 1,5- (pentamethylene) bis (trimetic anhydride) Retate anhydride), 1,6- (hexamethylene) bis (trimellitic anhydride), 1,7- (heptamethylene) bis (trimellitate anhydride), 1,8- (octamethylene) bis (trimellitic anhydride), 1,9- (nonamethylene) bis (trimellitic anhydride), 1,10- (decamethylene) bis (trimellitic anhydride), 1,12- (dodecamethylene) bis (trimellitic anhydride), 1,16- (hexadeca) Methylene) bis (trimellitate anhydride), 1,18- (octadecamethylene) bis (trimellitate anhydride), and the like.

  Examples of the tricarboxylic acid anhydride include trimellitic acid anhydride and nuclear hydrogenated trimellitic acid anhydride.

  Examples of the amine component include diamines such as aliphatic diamines and aromatic diamines, and polyvalent amines such as aliphatic polyether amines, but are not limited to these amines. These amine components may be used alone or in combination.

  Examples of the diamine include p-phenylenediamine (PPD), 1,3-diaminobenzene, 2,4-toluenediamine, 2,5-toluenediamine, 2,6-toluenediamine, 3,5-diaminobenzoic acid, One diamine nucleus diamine such as 2,5-diaminobenzoic acid and 3,4-diaminobenzoic acid, diaminodiphenyl ether such as 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, and 3,4′-diaminodiphenyl ether 4,4′-diaminodiphenylmethane, 3,3′-dimethyl-4,4′-diaminobiphenyl, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-bis (trifluoromethyl ) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiph Nilmethane, 3,3′-dicarboxy-4,4′-diaminodiphenylmethane, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, bis (4-aminophenyl) sulfide, 4, 4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (o-tolidine), 2,2'-dimethylbenzidine (m-tolidine), 3,3'-dimethoxybenzidine, 2 , 2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4 , 4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyls Hong, 3,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 3,3′-diaminobenzophenone, 3,3′-diamino-4,4′-dichlorobenzophenone, 3,3′-diamino- 4,4′-dimethoxybenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1, 1,1,3,3,3-hexafluoropropane, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfone Xoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-dicarboxy-4,4′-diaminodiphenylmethane, 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane, 3,3 ′ -Two diamine diamines such as diamino-4,4'-dihydroxydiphenylsulfone, 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4 -Bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) -4-trifluoromethylbenzene, 3,3 -Diamino-4- (4-phenyl) phenoxybenzophenone, 3,3'-diamino-4,4'-di (4-phenylphenoxy) benzophenone, 1,3-bis (3-aminophenyl sulfide) benzene, 1, 3-bis (4-aminophenyl sulfide) benzene, 1,4-bis (4-aminophenyl sulfide) benzene, 1,3-bis (3-aminophenylsulfone) benzene, 1,3-bis (4-aminophenyl) Sulfone) benzene, 1,4-bis (4-aminophenylsulfone) benzene, 1,3-bis [2- (4-aminophenyl) isopropyl] benzene, 1,4-bis [2- (3-aminophenyl) Isopropyl] benzene, 1,4-bis [2- (4-aminophenyl) isopropyl] benzene, 1,3-bis (4-amino) (3-hydroxyphenoxy) benzene and other benzene nucleus three diamines, 3,3′-bis (3-aminophenoxy) biphenyl, 3,3′-bis (4-aminophenoxy) biphenyl, 4,4′-bis ( 3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [3- (3-aminophenoxy) phenyl] ether, bis [3- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ketone, bis [3- (4-aminophenoxy) ) Phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophen Noxy) phenyl] ketone, bis [3- (3-aminophenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [ 4- (4-aminophenoxy) phenyl] sulfide, bis [3- (3-aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) Phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [3- (3-aminophenoxy) phenyl] methane, bis [3- (4-aminophenoxy) phenyl] methane, bis [4- (3-Aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] Tan, 2,2-bis [3- (3-aminophenoxy) phenyl] propane, 2,2-bis [3- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-amino Phenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3 , 3-hexafluoropropane, 2,2-bis [3- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3 -Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3 3-hexafluoropropane, etc. Aromatic diamine such as four diamines of benzene nucleus, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7- Examples include aliphatic diamines such as diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, and 1,2-diaminocyclohexane. Examples of the aliphatic polyether amine include ethylene glycol and / or propylene glycol-based polyvalent amine.

Diisocyanates such as aromatic diisocyanates and isomers and multimers, aliphatic diisocyanates, alicyclic diisocyanates and isomers thereof, and other general-purpose diisocyanates can be used as the isocyanate component. It is not limited. These isocyanate components may be used alone or in combination.
Examples of diisocyanates include aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, biphenyl diisocyanate, diphenyl sulfone diisocyanate, diphenyl ether diisocyanate, and isomers, multimers, hexamethylene diisocyanate, isophorone. Examples thereof include aliphatic diisocyanates such as diisocyanate, dicyclohexylmethane diisocyanate, and xylylene diisocyanate, alicyclic diisocyanates and isomers obtained by hydrogenation of the aromatic diisocyanate, and other general-purpose diisocyanates.

  The alkali-soluble resin having an imide ring as described above may have an amide bond. This may be an amide bond obtained by reacting an isocyanate and a carboxylic acid, or may be caused by other reaction. Furthermore, you may have the coupling | bonding which consists of another addition and condensation.

  In addition, for the introduction of the imide ring into the alkali-soluble resin, a known and commonly used alkali-soluble polymer, oligomer or monomer having a carboxyl group and / or an acid anhydride group may be used. It may be a resin obtained by reacting an alkali-soluble resin alone or in combination with the above carboxylic anhydride component and reacting with the above amine / isocyanate.

  In the synthesis of such an alkali-soluble resin having an alkali-soluble group and an imide ring, a known and commonly used organic solvent can be used. Such an organic solvent is not particularly limited as long as it is a solvent that does not react with the carboxylic acid anhydrides, amines, and isocyanates that are raw materials and that dissolves these raw materials, and the structure is not particularly limited. Specifically, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone , Cyclic ester solvents such as α-methyl-γ-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, lactam solvents such as caprolactam, ether solvents such as dioxane, glycol solvents such as triethylene glycol, m-cresol, Phenolic solvents such as p-cresol, 3-chlorophenol, 4-chlorophenol, 4-methoxyphenol, 2,6-dimethylphenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl Sulfo Sid, such as tetramethylurea. Furthermore, other common organic solvents such as phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran , Dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, terpene, mineral spirit, petroleum naphtha solvents, etc. Can also be used. Of these, aprotic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and γ-butyrolactone are preferred because of the high solubility of the raw materials.

The alkali-soluble resin having an alkali-soluble group such as a carboxyl group or an acid anhydride group and an imide ring as described above has an acid value of 20 to 200 mgKOH / g in order to cope with the photolithography process. Is more preferable, and 60 to 150 mgKOH / g is more preferable. When this acid value is 20 mgKOH / g or more, solubility in alkali is improved, and developability is improved. Furthermore, since the degree of crosslinking with the thermosetting component after light irradiation is increased, a sufficient development contrast can be obtained.
Moreover, when this acid value is 200 mgKOH / g or less, what is called a hot fog in the PEB process after light irradiation mentioned later can be suppressed, and a process margin becomes large.

The molecular weight of the alkali-soluble resin is preferably from 1,000 to 100,000, more preferably from 2,000 to 50,000, considering developability and cured coating properties.
When the molecular weight is 1,000 or more, sufficient development resistance and cured product properties can be obtained after light irradiation and PEB. On the other hand, when the molecular weight is 100,000 or less, alkali solubility is improved and development is improved.

(Photobase generator)
The photobase generator used in the resin layer (B) is used as a catalyst for the polymerization reaction of a thermoreactive compound, which will be described later, when the molecular structure is changed by light irradiation such as ultraviolet light or visible light, or when the molecule is cleaved. It is a compound that produces one or more basic substances that can function. Examples of basic substances include secondary amines and tertiary amines.
Examples of photobase generators include α-aminoacetophenone compounds, oxime ester compounds, acyloxyimino groups, N-formylated aromatic amino groups, N-acylated aromatic amino groups, nitrobenzyl carbamate groups, and alkoxyoxybenzyl carbamates. And compounds having a substituent such as a group. Of these, oxime ester compounds and α-aminoacetophenone compounds are preferred. As the α-aminoacetophenone compound, those having two or more nitrogen atoms are particularly preferable.

  Other photobase generators include WPBG-018 (trade name: 9-anthrylmethylN, N'-diethylcarbamate), WPBG-027 (trade name: (E) -1- [3- (2-hydroxyphenyl) -2-propenoyl ] piperidine), WPBG-082 (trade name: guanidinium2- (3-benzoylphenyl) propionate), WPBG-140 (trade name: 1- (anthraquinon-2-yl) ethyl imidazolecarboxylate), and the like can also be used.

  The α-aminoacetophenone compound has a benzoin ether bond in the molecule, and when irradiated with light, cleavage occurs in the molecule to produce a basic substance (amine) that exhibits a curing catalytic action. Specific examples of the α-aminoacetophenone compound include (4-morpholinobenzoyl) -1-benzyl-1-dimethylaminopropane (Irgacure 369, trade name, manufactured by BASF Japan Ltd.) and 4- (methylthiobenzoyl) -1-methyl. -1-morpholinoethane (Irgacure 907, trade name, manufactured by BASF Japan Ltd.), 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl]- A commercially available compound such as 1-butanone (Irgacure 379, trade name, manufactured by BASF Japan Ltd.) or a solution thereof can be used.

  Any oxime ester compound can be used as long as it is a compound that generates a basic substance by light irradiation. Examples of such oxime ester compounds include CGI-325, Irgacure OXE01, Irgacure OXE02 manufactured by BASF Japan, N-1919, and NCI-831 manufactured by Adeka. Moreover, the compound which has two oxime ester groups in the molecule | numerator described in the patent 4344400 gazette can also be used suitably.

  In addition, JP-A-2004-359639, JP-A-2005-097141, JP-A-2005-220097, JP-A-2006-160634, JP-A-2008-094770, JP-A-2008-509967, Specific examples include carbazole oxime ester compounds described in JP2009-040762A and JP2011-80036A.

  Such a photobase generator may be used individually by 1 type, and may be used in combination of 2 or more type. The blending amount of the photobase generator in the photosensitive thermosetting resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 30 parts by mass with respect to 100 parts by mass of the thermoreactive compound. Part by mass. In the case of 0.1 parts by mass or more, the development resistance contrast of the light irradiated part / non-irradiated part can be favorably obtained. Moreover, in 40 mass parts or less, hardened | cured material characteristic improves.

(Thermo-reactive compound)
The heat-reactive compound used in the resin layer (B) is a resin having a functional group capable of undergoing a curing reaction by heat, preferably a resin having a cyclic (thio) ether group, more preferably an epoxy resin, Examples include polyfunctional oxetane compounds. The cyclic (thio) ether group means at least one of a cyclic ether group and a cyclic thioether group.

  The epoxy resin is a resin having an epoxy group, and any known one can be used. Examples thereof include a bifunctional epoxy resin having two epoxy groups in the molecule, and a polyfunctional epoxy resin having many epoxy groups in the molecule. In addition, a hydrogenated bifunctional epoxy compound may be used.

  Polyfunctional epoxy compounds include bisphenol A type epoxy resin, brominated epoxy resin, novolac type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, alicyclic ring Epoxy resin, trihydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin or a mixture thereof; bisphenol S type epoxy resin, bisphenol A novolak type epoxy resin, tetraphenylolethane type epoxy resin, heterocyclic epoxy Resin, diglycidyl phthalate resin, tetraglycidyl xylenoyl ethane resin, naphthalene group-containing epoxy resin, epoxy resin having dicyclopentadiene skeleton, glycidyl meta Acrylate copolymer epoxy resins, copolymerized epoxy resins of cyclohexylmaleimide and glycidyl methacrylate, and a CTBN modified epoxy resin.

  Other liquid bifunctional epoxy resins include vinylcyclohexene diepoxide, (3 ′, 4′-epoxycyclohexylmethyl) -3,4-epoxycyclohexanecarboxylate, and (3 ′, 4′-epoxy-6′-methyl). And alicyclic epoxy resins such as (cyclohexylmethyl) -3,4-epoxy-6-methylcyclohexanecarboxylate. These epoxy resins may be used individually by 1 type, and may use 2 or more types together.

  Examples of the polyfunctional oxetane compound include bis [(3-methyl-3-oxetanylmethoxy) methyl] ether, bis [(3-ethyl-3-oxetanylmethoxy) methyl] ether, 1,4-bis [(3-methyl -3-Oxetanylmethoxy) methyl] benzene, 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, (3-methyl-3-oxetanyl) methyl acrylate, (3-ethyl-3-oxetanyl) In addition to polyfunctional oxetanes such as methyl acrylate, (3-methyl-3-oxetanyl) methyl methacrylate, (3-ethyl-3-oxetanyl) methyl methacrylate and oligomers or copolymers thereof, oxetane alcohol and novolak resin, Poly (p-hydroxystyrene), cardo-type bisphenol Le ethers, calixarenes, calix resorcin arenes, or the like ethers of a resin having a hydroxyl group such as silsesquioxane and the like. In addition, a copolymer of an unsaturated monomer having an oxetane ring and an alkyl (meth) acrylate is also included.

As a compounding quantity of the said thermoreactive compound, equivalent ratio (alkali-soluble groups, such as a carboxyl group: thermal-reactive groups, such as an epoxy group) with alkali-soluble resin is 1: 0.1 to 1:10. It is preferable. In such a blending ratio, development becomes easy. The equivalent ratio is more preferably 1: 0.2 to 1: 5.
In addition, conventionally known thermosetting catalysts, thermoplastic resins, inorganic fillers, colorants, organic solvents, and the like can be appropriately blended.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited by these Examples and a comparative example.

Examples 1 and 2 and Comparative Example 1
<Synthesis example of an alkali-soluble resin having an imide ring>
In a separable three-necked flask equipped with a stirrer, nitrogen inlet tube, fractional ring, and cooling ring, 12.5 g of 3,5-diaminobenzoic acid, 2,2′-bis [4- (4-aminophenoxy) Phenyl] propane (8.2 g), NMP (30 g), γ-butyrolactone (30 g), 4,4′-oxydiphthalic anhydride (27.9 g) and trimellitic anhydride (3.8 g) were added at room temperature under a nitrogen atmosphere at 100 rpm. Stir for 4 hours. Next, 20 g of toluene was added and stirred for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 ° C. and 150 rpm to obtain an alkali-soluble resin solution having an imide ring.

<Preparation of resin composition>
In accordance with the formulation shown in Table 1 below, the materials described in the examples were respectively blended, premixed with a stirrer, and then kneaded with a three-roll mill to prepare resin compositions for the resin layers (A) and (B). did. The values in the table are parts by mass unless otherwise specified.

<Formation process of resin layer (A)>
A flexible printed wiring substrate in which a circuit was formed with a copper thickness of 18 μm was prepared, and pre-treatment was performed using MEC CZ-8100. Then, the flexible printed wiring board which performed the said pre-processing was coated so that it might become 25 micrometers after drying with the coating method shown in Table 1, respectively for the resin composition of Examples 1, 2 and Comparative Example 1. Then, it dried at 90 degreeC / 30 minutes with the hot-air circulation type drying furnace, and formed the resin layer (A).

<Formation step of resin layer (B)>
The photosensitive thermosetting resin compositions of Examples 1 and 2 were coated on the resin layer (A) by a coating method shown in Table 1 so as to have a thickness of 10 μm after drying. Then, it dried at 90 degreeC / 30 minutes with the hot-air circulation type drying furnace, and formed the resin layer (B). In Comparative Example 1, the resin layer (B) was not formed.

<Developability (patterning) and evaluation of curing characteristics>
In Examples 1 and 2, with respect to the flexible printed wiring board provided with the resin layers (A) and (B) obtained above, the exposure amount shown in Table 1 with ORC HMW680GW (metal halide lamp, scattered light) is used. Light was irradiated in a negative pattern. Next, heat treatment was performed at 90 ° C. for 60 minutes. Thereafter, the substrate was immersed in a 1% by mass sodium carbonate aqueous solution at 30 ° C. and developed for 3 minutes to evaluate the developability. In Comparative Example 1, the possibility of developability was evaluated in the same manner as in Example 1 for the flexible printed wiring board provided with the resin layer (A) obtained above. The obtained results are shown in Table 1.

  Next, heat treatment was performed at 150 ° C./60 minutes using a hot air circulation drying oven to obtain a patterned cured coating film. An MIT test (R = 0.38 mm / upilex 12.5 μm base material manufactured by Ube Industries, Ltd.) and a surface hardness test (pencil hardness test) were conducted on the obtained cured coating film, and the flexibility and surface Hardness (impact resistance) was evaluated. The obtained results are shown in Table 1 below.

＊１酸価８６ｍｇＫＯＨ／ｇ Ｍｗ：１００００
＊２ビスフェノールＡ型エポキシ樹脂(分子量：３８０）（三菱化学(株)製）
＊３オキシム型光重合開始剤（ＢＡＳＦ社製）
＊４ビスフェノールＦ型エポキシアクリレート（日本化薬(株)製）
＊５トリメチロールプロパンＥＯ 変性トリアクリレート（東亞合成(株)製）
＊６ビスフェノールＡ型エポキシ樹脂(分子量：９００）（三菱化学(株)製）
＊７ビスフェノールＡ型エポキシ樹脂(分子量：５００）（三菱化学(株)製）
＊８アシルフォスフィンオキサイド系光重合開始剤 (ＢＡＳＦ社製)

* 1 Acid value 86 mg KOH / g Mw: 10,000
* 2 Bisphenol A type epoxy resin (Molecular weight: 380) (Mitsubishi Chemical Corporation)
* 3 Oxime-type photopolymerization initiator (BASF)
* 4 Bisphenol F epoxy acrylate (manufactured by Nippon Kayaku Co., Ltd.)
* 5 Trimethylolpropane EO modified triacrylate (manufactured by Toagosei Co., Ltd.)
* 6 Bisphenol A epoxy resin (Molecular weight: 900) (Mitsubishi Chemical Corporation)
* 7 Bisphenol A type epoxy resin (Molecular weight: 500) (Mitsubishi Chemical Corporation)
* 8 Acylphosphine oxide photopolymerization initiator (BASF)

  From the evaluation results shown in Table 1, the flexible printed wiring boards of Examples 1 and 2 can form a fine pattern similarly to the flexible printed wiring board of Comparative Example 1, and bendability and impact resistance (surface hardness). Can be seen to be significantly better.

DESCRIPTION OF SYMBOLS 1 Flexible printed wiring board 2 Copper circuit 3 Resin layer 4 Resin layer 5 Mask

Claims (2)

A step of forming at least one resin layer (A) made of the alkali-developable photosensitive resin composition (A1) on the flexible printed wiring board;
On the resin layer (A), at least a resin layer (B) comprising a photosensitive thermosetting resin composition (B1) containing an alkali-soluble resin having an imide ring, a photobase generator, and a heat-reactive compound. A step of forming one layer,
Irradiating the resin layers (A) and (B) formed in the step with light in a pattern;
Heating the resin layers (A) and (B) irradiated with light in the step; and
A step of alkali-developing the light-irradiated resin layers (A) and (B) to form at least one of a coverlay and a solder resist;
The manufacturing method of the flexible printed wiring board characterized by including.   A flexible printed wiring board manufactured by the method for manufacturing a flexible printed wiring board according to claim 1.

Images