KR20230005409A - Manufacturing method of flexible printed circuit board - Google Patents

Abstract

A method for manufacturing a flexible printed circuit board is a liquid phase coating method using a vertical suspension roll coater on both sides of a substrate 11 having a film support 13 and wirings 14 provided on both sides of the film support 13. A step of applying the photosensitive resin composition 17 is provided. A hole 15 is provided in the substrate 11 . The viscosity after rotating the liquid photosensitive resin composition 17 at 50 rpm for 3 minutes is 1.0 Pa.s or more and 15.0 Pa.s or less. The ratio of the viscosity of the liquid photosensitive resin composition 17 after being rotated for 3 minutes at a rotation speed of 5 rpm to the viscosity after rotation at a rotation speed of 50 rpm for 3 minutes is 1.5 or more and 3.0 or less. The elastic modulus of the cured film of the liquid photosensitive resin composition 17 is 0.1 GPa or more and 1.5 GPa or less. When the liquid photosensitive resin composition 17 is applied, the liquid photosensitive resin composition 17 is simultaneously applied to both sides of the substrate 11 .

Description

Manufacturing method of flexible printed circuit board

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

With the miniaturization, weight reduction, and multifunctionalization of electronic components, the openings of flexible printed circuit boards built into the inside of electronic devices have fineness enabling components to be mounted on small-diameter lands (hereinafter referred to as “fine openings”). has) is required. A method for forming fine openings in a flexible printed circuit board, wherein a film containing a liquid photosensitive resin composition is formed on a component mounting portion of a flexible printed circuit board (hereinafter sometimes simply referred to as "substrate") before a protective film is formed, A method of patterning this film by photolithography to form a protective film provided with fine openings is known.

Further, in recent years, with the increase in screen size and thinning of portable devices represented by smartphones, flexible printed circuit boards used in portable devices are easy to fold into a narrow part and incorporate, so that the bent shape can be easily maintained. Saints are also required. [0002] As a method for improving the low resilience of a flexible printed circuit board, a method of partially applying a thermosetting resin composition called bending ink to a bent portion of the substrate is known.

In addition, the flexible printed circuit board is usually provided with through holes (through holes) or non-through holes (blind vias), and when applying the liquid photosensitive resin composition to the substrate, the liquid photosensitive resin composition is applied to the through holes or non-through holes. It needs to be landfilled. For this reason, flexible printed circuit boards are also required to sufficiently embed the liquid photosensitive resin composition in through-holes and non-through-holes (hereinafter sometimes referred to as "embedded property"). In addition, in the following, a through hole and a non-through hole may be collectively described as a "hole". In addition, in the following, a hole means one hole or a plurality of holes. In addition, the substrate provided with holes includes a substrate provided with only through holes, a substrate provided with only non-through holes, and a substrate provided with both through holes and non-through holes.

Under these circumstances, various resin compositions for protective films (specifically, liquid photosensitive resin compositions, etc.) and coating devices for resin compositions for protective films have been studied in order to improve the fine opening properties, low repulsion properties or embedding properties of flexible printed circuit boards. (For example, see Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2015-161764 Japanese Unexamined Patent Publication No. 2020-148971 International Publication No. 2018/092330 Japanese Unexamined Patent Publication No. 2015-115602

However, only the techniques described in Patent Literatures 1 to 4 suppress the appearance defects of the coating film containing the resin composition for a protective film (hereinafter sometimes simply referred to as "coating film") and the appearance defect of the substrate on which the coating film is formed. difficult. Both the appearance defect of the coating film and the appearance defect of the substrate on which the coating film is formed lead to a decrease in product yield.

The present invention has been made in view of these problems, and its object is to provide a method for manufacturing a flexible printed circuit board capable of suppressing the appearance defects of a coating film and appearance defects of a substrate on which a coating film is formed.

A method for manufacturing a flexible printed circuit board according to the present invention is a step of applying a liquid photosensitive resin composition to both surfaces of a substrate having a film-like support and wiring provided on both sides of the film-like support using a vertical suspension roll coater. to provide A hole is provided in the board. The vertical suspension roll coater includes a pair of coating rolls each having a plurality of independent ring-shaped grooves. The roll diameter of the said application roll is 70 mm or more and 150 mm or less. The liquid photosensitive resin composition has a viscosity of 1.0 Pa·s or more and 15.0 Pa·s or less after being rotated at a rotation speed of 50 rpm for 3 minutes, and is rotated for 3 minutes at a rotation speed of 5 rpm for a viscosity after being rotated for 3 minutes at a rotation speed of 50 rpm. The viscosity ratio after being made is 1.5 or more and 3.0 or less. The elastic moduli of the cured film of the said liquid photosensitive resin composition are 0.1 GPa or more and 1.5 GPa or less. When applying the liquid photosensitive resin composition, the liquid photosensitive resin composition is simultaneously applied to both surfaces of the substrate.

In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, both the horizontal width and the vertical width of the film-shaped support are 200 mm or more and 600 mm or less.

In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the thickness of the film-like support is 8.0 μm or more and 50.0 μm or less.

In the manufacturing method of the flexible printed circuit board according to one embodiment of the present invention, the thickness of the wiring is 8 μm or more and 50 μm or less.

In the manufacturing method of the flexible printed circuit board according to one embodiment of the present invention, the diameter of the hole is 50 μm or more and 250 μm or less.

In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the film-shaped support is made of polyimide, polyamide, polyester, polycarbonate, polyarylate, polytetrafluoroethylene, or polychlorotrifluoroethylene. from the group consisting of ethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesins, tetrafluoroethylene/hexafluoropropylene copolymers, ethylene/tetrafluoroethylene copolymers, and ethylene/chlorotrifluoroethylene copolymers; It includes one or more selected polymers.

In the method for producing a flexible printed circuit board according to one embodiment of the present invention, the ratio of the viscosity of the liquid photosensitive resin composition after rotating at a rotational speed of 50rpm for 3 minutes to the viscosity after rotating at a rotational speed of 50rpm for 24 hours is 1.20 or less. .

In the method for producing a flexible printed circuit board according to an embodiment of the present invention, the liquid photosensitive resin composition contains a binder polymer, a radical photopolymerization initiator, a thermosetting resin, particles having an average particle diameter of 0.01 μm or more and 100 μm or less, and an organic solvent. .

In the method for producing a flexible printed circuit board according to an embodiment of the present invention, the binder polymer is a polymer having a urethane bond in one molecule, a polymer having an imide group in one molecule, and a (meth)acryloyl group in one molecule. It is one or more types of polymers selected from the group consisting of polymers and polymers having a carboxyl group in one molecule.

In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the organic solvent is a water-soluble organic solvent having a boiling point of 180°C or higher.

In the manufacturing method of the flexible printed circuit board according to one embodiment of the present invention, the content of the particles is 5 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the binder polymer.

In the method for producing a flexible printed circuit board according to an embodiment of the present invention, the particles are crosslinked polymer particles.

According to the present invention, it is possible to provide a method for manufacturing a flexible printed circuit board capable of suppressing occurrence of appearance defects of a coating film and appearance defects of a substrate on which a coating film is formed.

1 is a cross-sectional view of main parts for explaining an example of a method for manufacturing a flexible printed circuit board according to the present invention.
2 is another main part sectional view for explaining an example of the manufacturing method of the flexible printed circuit board concerning this invention.
3 is another main part sectional view for explaining an example of the manufacturing method of the flexible printed circuit board concerning this invention.
4 is another main part sectional view for explaining an example of the manufacturing method of the flexible printed circuit board concerning this invention.
5 is another main part sectional view for explaining an example of the manufacturing method of the flexible printed circuit board concerning this invention.
Fig. 6 is a cross-sectional view when an application roll used in an example of a method for manufacturing a flexible printed circuit board according to the present invention is cut along a plane including its axis.

Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. In addition, all of the scientific literature and patent literature described in this specification are incorporated as a reference in this specification.

First, terms used in this specification will be described. A "roll coater" is an application device having a pair of rotatable application rolls. The coating method of the roll coater includes a vertical suspension pulling method in which the liquid photosensitive resin composition is applied to the substrate while the substrate is suspended in the vertical direction, and a horizontal transport method in which the liquid photosensitive resin composition is applied to the substrate while conveying the substrate in the horizontal direction. Compared with a horizontal conveyance type roll coater, a vertical suspension type roll coater can simplify and save space of an application apparatus. In addition, since the vertical suspension roll coater can dry the substrate coated with the liquid photosensitive resin composition in a suspended state, it is possible to suppress adhesion of foreign substances in the drying process of the coating film.

The "thickness" of the film-like support is 10 measurement values obtained by randomly selecting 10 measurement points from an electron microscope image of a cross-section of the film-like support cut in the thickness direction and measuring the thickness of the selected 10 measurement points. is the arithmetic mean of The "thickness" of a wiring is the arithmetic mean value of 10 measured values obtained by randomly selecting 10 measurement points from an electron microscope image of a cross-section of the wire cut in the thickness direction and measuring the thickness of the selected 10 measurement points. . "Viscosity" is a viscosity measured at a measurement temperature of 25°C using a Brookfield rotational viscometer. A method for measuring the viscosity is the same method as or a method similar to that of Examples described later.

The "cured film of the liquid photosensitive resin composition" is a coating film containing the liquid photosensitive resin composition after curing. Hereinafter, the cured film of the liquid photosensitive resin composition may be simply referred to as a "cured film". In addition, in this specification, "after curing" refers to a state in which an increase in the modulus of elasticity of the coating film is no longer seen even if further heated. Specifically, with respect to the coating film, even if it is further heated at a temperature of 150°C for 60 minutes, it refers to a state in which the range of increase in the elastic modulus of the coating film is less than 0.01 GPa. The method for measuring the modulus of elasticity is the same method as or a method similar to that of Examples described later.

A "photoradical polymerization initiator" refers to a compound that generates radicals as active species upon irradiation with light.

The "average particle diameter" is the volume-based median diameter (relative to the integrated distribution value of 50%) measured using a laser diffraction/scattering type particle size distribution analyzer (for example, "LA-950V2" manufactured by Horiba Seisakusho Co., Ltd.) particle size).

Hereinafter, "system" is appended to the compound name to collectively refer to compounds and their derivatives in some cases. When a polymer name is indicated by appending "system" to the end of the compound name, it means that the repeating unit of the polymer is derived from a compound or a derivative thereof. In addition, there are cases where acryl and methacryl are collectively referred to as "(meth)acryl". In addition, acrylates and methacrylates are collectively referred to as "(meth)acrylates" in some cases. In addition, an acryloyl group and a methacryloyl group are collectively referred to as "(meth)acryloyl group" in some cases. The components, functional groups, etc. exemplified in this specification may be used alone or in combination of two or more, unless otherwise specified.

The drawings referred to in the following description are schematically showing each component as a main body for easy understanding, and the size, number, shape, etc. of each component shown are actual from the point of view of drawing. may be different from In addition, for convenience of explanation, in the drawings described later, the same reference numerals are assigned to the same components as those in the previously described drawings, and the description thereof may be omitted.

<Method of manufacturing flexible printed circuit board>

The method for manufacturing a flexible printed circuit board according to the present embodiment includes a step of applying a liquid photosensitive resin composition to both surfaces of the substrate using a vertical suspension roll coater. The substrate has a film-like support and wiring provided on both sides of the film-like support. A hole is provided in the substrate. A vertical suspension pull-up type roll coater includes a pair of coating rolls each having a plurality of independent ring-shaped grooves. The roll diameter of an application roll is 70 mm or more and 150 mm or less. The viscosity after rotating the liquid photosensitive resin composition for 3 minutes at a rotational speed of 50 rpm is 1.0 Pa·s or more and 15.0 Pa·s or less. The ratio of the viscosity after rotating the liquid photosensitive resin composition at a rotation speed of 50 rpm for 3 minutes to the viscosity after rotation for 3 minutes at a rotation speed of 5 rpm is 1.5 or more and 3.0 or less. The elastic modulus of the cured film of the liquid photosensitive resin composition is 0.1 GPa or more and 1.5 GPa or less. When applying the liquid photosensitive resin composition, the liquid photosensitive resin composition is simultaneously applied to both sides of the substrate.

In the manufacturing method of the flexible printed circuit board according to the present embodiment, since the liquid photosensitive resin composition is simultaneously applied to both surfaces of the substrate when applying the liquid photosensitive resin composition, the liquid photosensitive resin composition can be applied while filling holes provided in the substrate. can

Hereinafter, the ratio of the viscosity B after rotating the liquid photosensitive resin composition at a rotational speed of 50rpm for 3 minutes to the viscosity A after rotating for 3 minutes at a rotational speed of 5rpm (B / A) is referred to as "TI value, which is an abbreviation of thixotropic index value. 」 in some cases. In addition, the viscosity after rotating the liquid photosensitive resin composition at a rotational speed of 50 rpm for 3 minutes (the viscosity indicated by a Brookfield rotational viscometer 3 minutes after the start of rotation) may be simply described as "viscosity". The viscosity can be adjusted by changing the solid content concentration of the liquid photosensitive resin composition, for example. TI value can be adjusted by changing the quantity of particle|grains (for example, component (D) mentioned later) in a liquid photosensitive resin composition, for example.

According to the present embodiment, it is possible to provide a method for manufacturing a flexible printed circuit board capable of suppressing occurrence of appearance defects of a coating film and appearance defects of a substrate on which a coating film is formed. The reason is estimated as follows.

The vertical suspension pull-up type roll coater used in the present embodiment includes a pair of application rolls, and each application roll has a plurality of ring-shaped grooves. And, each of the plurality of ring-shaped grooves is independent. For this reason, in this embodiment, when applying the liquid photosensitive resin composition to the substrate, in the case of applying with an application roll provided with one spiral groove (hereinafter, simply referred to as "spiral groove") In contrast, the substrate provided with the film-shaped support and the grooves are in uniform contact. Further, in this embodiment, when applying the liquid photosensitive resin composition to the substrate, the liquid photosensitive resin composition is simultaneously applied to both surfaces of the substrate. From this point of view, in this embodiment, when applying the liquid photosensitive resin composition to the substrate, since the roll pressure can be transmitted uniformly to the substrate, deformation of the substrate can be suppressed.

In addition, in this embodiment, since the elastic modulus of the cured film of the liquid photosensitive resin composition is in the range of 0.1 GPa or more and 1.5 GPa or less, and the roll diameter of the application roll is 150 mm or less, according to the present embodiment, the substrate has a liquid photosensitive property. When applying the resin composition, breakage (specifically, tearing, etc.) of the substrate caused by roll pressure can be suppressed.

In this way, according to the present embodiment, when the liquid photosensitive resin composition is applied to the substrate, deformation of the substrate and damage to the substrate can be suppressed, so that the appearance defect of the substrate on which the coating film is formed can be suppressed.

Further, in general, when a liquid photosensitive resin composition is simultaneously applied to both sides of a substrate using a vertical suspension roll coater, in a substrate where the support is not in the form of a film (rigid substrate, multilayer substrate, etc.), the support is the roll during coating. Since it can withstand pressure, deformation, tearing, etc. of the substrate are less likely to occur. On the other hand, when a liquid photosensitive resin composition is simultaneously applied to both sides of a substrate having a film-like support using a vertical suspension roll coater, usually the film-like support cannot withstand the roll pressure during coating, resulting in deformation of the substrate, It is easy to cause tearing, etc. However, in the present embodiment, as described above, when the liquid photosensitive resin composition is applied to the substrate, deformation of the substrate and damage to the substrate can be suppressed, so that occurrence of defects in appearance of the substrate on which the coating film is formed can be suppressed. .

Moreover, in this embodiment, since the roll diameter of an application roll is 70 mm or more, the phenomenon (liquid pool) in which the liquid photosensitive resin composition excessively stays between an application roll and a board|substrate tends to become difficult to occur. Therefore, in the present embodiment, in the coating film formed by application of the liquid photosensitive resin composition, there is a tendency for the occurrence of groove marks and stripes of the application roll to be suppressed. In addition, in this embodiment, since the viscosity of the liquid photosensitive resin composition is 1.0 Pa.s or more and 15.0 Pa.s or less, and the TI value of the liquid photosensitive resin composition is 1.5 or more and 3.0 or less, by application|coating of the liquid photosensitive resin composition In the coating film formed, the occurrence of pinholes and coating unevenness tends to be suppressed. From this point of view, according to the present embodiment, occurrence of poor appearance of the coating film can be suppressed.

In this embodiment, in order to further suppress the appearance defect of the coating film, the viscosity of the liquid photosensitive resin composition is preferably 1.5 Pa·s or more and 13.0 Pa·s or less, and is 2.0 Pa·s or more and 12.0 Pa·s or less. it is more preferable

In this embodiment, in order to further suppress the appearance defect of the coating film, the TI value of the liquid photosensitive resin composition is preferably 1.6 or more and 2.7 or less, and more preferably 1.7 or more and 2.5 or less.

In this embodiment, in order to further suppress the appearance defect of the board|substrate on which the coating film was formed, it is preferable that the elastic modulus of the cured film of a liquid photosensitive resin composition is 0.2 GPa or more and 1.4 GPa or less, and it is more preferable that it is 0.3 GPa or more and 1.3 GPa or less. . The modulus of elasticity of the cured film of the liquid photosensitive resin composition is, for example, the type and amount of the binder polymer in the liquid photosensitive resin composition, and the type and amount of particles (for example, component (D) described later) in the liquid photosensitive resin composition. can be adjusted by changing at least one of them.

In this embodiment, in order to further suppress the appearance defect of the substrate on which the coating film is formed, the horizontal width and vertical width of the film-like support are both preferably 150 mm or more and 650 mm or less, and both are more preferably 200 mm or more and 600 mm or less. And, it is more preferable that both are 250 mm or more and 550 mm or less. In addition, "lateral width of a film-shaped support body" means the width of a film-shaped support body in the direction parallel to the axial center direction of an application roll, when apply|coating a liquid photosensitive resin composition to a board|substrate. In addition, "the vertical width of a film-shaped support body" means the width|variety of a film-shaped support body in the direction orthogonal to the axial center direction of an application roll, when apply|coating a liquid photosensitive resin composition to a board|substrate.

In this embodiment, in order to further suppress the appearance defect of the substrate on which the coating film is formed, the thickness of the film-shaped support is preferably 8.0 μm or more, more preferably 10.0 μm or more, and even more preferably 12.0 μm or more. Further, in the present embodiment, in order to further suppress the appearance defect of the coating film, it is preferable that the thickness of the film-like support is 50.0 μm or less.

In the present embodiment, in order to further suppress the appearance defect of the coating film, the thickness of the wiring is preferably 8 μm or more and 50 μm or less, more preferably 10 μm or more and 50 μm or less, and 15 μm or more and 50 μm or less. it is more preferable

In this embodiment, in order to obtain a flexible printed circuit board excellent in embedding property while ensuring conduction between wirings provided on both sides of the film-shaped support, the diameter (opening diameter) of the hole provided in the board is 50 μm or more and 250 μm or less. It is preferable, and it is more preferable that they are 50 micrometers or more and 200 micrometers or less.

In the present embodiment, when the vertical suspension roll coater is operated continuously for a long time and the application step of the liquid photosensitive resin composition is continuously performed for a long time, in order to suppress the sticking of the substrate to the coating roll, the liquid photosensitive resin composition The ratio (C/A) of the viscosity C after rotation at a rotation speed of 50 rpm for 24 hours to the viscosity A after rotation at a rotation speed of 50 rpm for 3 minutes (C/A) is preferably 1.20 or less, and more preferably 1.15 or less. Hereinafter, the ratio (C/A) of the viscosity C after rotating the liquid photosensitive resin composition at a rotational speed of 50rpm for 24 hours to the viscosity A after rotating at a rotational speed of 50rpm for 3 minutes (C/A) is referred to as "viscosity ratio over time". there is. The lower limit of the viscosity ratio over time is not particularly limited, and may be, for example, 1.00. Moreover, sticking of a board|substrate to an application roll leads to the fall of the yield of a product. The viscosity ratio with the passage of time can be adjusted by changing the kind of organic solvent contained in the liquid photosensitive resin composition, for example. When an organic solvent with a high boiling point is used, the viscosity ratio over time decreases.

In this embodiment, in order to further suppress the appearance defects of the coating film and the appearance defects of the substrate on which the coating film is formed, it is preferable to satisfy the following condition 1, and it is more preferable to satisfy the following conditions 1 and 2. Further, in the present embodiment, while further suppressing the appearance defects of the coating film and the appearance defects of the substrate on which the coating film is formed, the vertical suspension roll coater is continuously operated for a long time, and the application step of the liquid photosensitive resin composition is performed for a long time. When performed continuously, in order to suppress the sticking of the substrate to the coating roll, it is preferable to satisfy the following conditions 1 and 3, and it is more preferable to satisfy the following conditions 1, 2 and 3.

Condition 1: Both the horizontal and vertical widths of the film-like support are 200 mm or more and 600 mm or less, and the film-like support has a thickness of 8.0 μm or more and 50.0 μm or less.

Condition 2: The thickness of the wiring is 8 μm or more and 50 μm or less.

Condition 3: The viscosity ratio over time of the liquid photosensitive resin composition is 1.20 or less.

Hereinafter, this embodiment will be described with appropriate reference to the drawings. 1 to 5 to be referred to are main part cross-sectional views for explaining an example of a method for manufacturing a flexible printed circuit board according to the present embodiment (particularly, an application step). 1 to 5, the left side of the drawing is referred to as the upstream side of the manufacturing process, and the right side of the drawing is referred to as the downstream side of the manufacturing process.

In the application process of this embodiment, first, the substrate 11 suspended by the suspension jig 10 is transferred from the upstream side of the manufacturing process to the upper side of the pair of application rolls 12a and 12b (FIG. 1). . 1, the application roll 12a is an application roll located on the upstream side of a manufacturing process, and the application roll 12b is an application roll located on the downstream side of a manufacturing process. As for the application roll 12a and the application roll 12b, both have a roll diameter of 70 mm or more and 150 mm or less. Further, the substrate 11 has a film support 13 and wirings 14 provided on both surfaces of the film support 13 . A hole 15 is provided in the substrate 11 . The width of the wiring 14 is, for example, 10 μm or more and 200 μm or less. The spacing (pitch) of the wirings 14 is, for example, 10 μm or more and 200 μm or less.

In the state of FIG. 1 , between the application roll 12a and the application roll 12b, there is provided a space enough to pass through the substrate 11 . The application roll 12a is in contact with the doctor bar 16a on the upstream side of the manufacturing process, and a predetermined pressure (for example, 0.5 kgf/cm 2 or more and 3.0 kgf/cm 2 or less) is applied from the doctor bar 16a. . The application roll 12b is in contact with the doctor bar 16b on the downstream side of the manufacturing process, and a predetermined pressure (for example, 0.5 kgf/cm 2 or more and 3.0 kgf/cm 2 or less) is applied from the doctor bar 16b. .

In addition, the application roll 12a and the application roll 12b rotate at predetermined rotational speeds (for example, 1 m/min or more and 10 m/min or less), respectively. Between the application roll 12a and the doctor bar 16a and between the application roll 12b and the doctor bar 16b, the liquid photosensitive resin composition 17 is collected. The liquid photosensitive resin composition 17 is transferred to the surface of the application roll 12a and the surface of the application roll 12b.

From the state shown in Fig. 1, the suspension jig 10 descends, and the suspended substrate 11 passes between the application rolls 12a and 12b, and the upper end of the substrate 11 falls on the application roll 12a. It is conveyed to a place (refer to Fig. 2) located between the coating roll 12b. Then, as shown in FIG. 2 , the suspension jig 10 separates the substrate 11 and the fixing jig 18 grips the lower end of the substrate 11 .

Next, the rotating application roll 12a and the application roll 12b press the substrate 11 so that the substrate 11 is sandwiched therebetween and the substrate 11 is pressurized, and the fixing jig 18 ) is spaced apart from the lower end of the substrate 11 (FIG. 3). When the substrate 11 is separated from the fixing jig 18, since the application roll 12a and the application roll 12b are rotating, the liquid photosensitive resin composition 17 is simultaneously applied to both sides of the substrate 11 while , the substrate 11 is lifted upward. In addition, in the state of FIG. 3, the press-in amount of the application roll 12a and the application roll 12b is the range of 100 micrometers or more and 200 micrometers or less, for example.

Next, while the liquid photosensitive resin composition 17 is applied on both sides simultaneously, the upper end of the substrate 11 lifted upward is held by the suspension jig 10 (FIG. 4). When the substrate 11 is lifted, the liquid photosensitive resin composition 17 is embedded in the hole 15 provided in the substrate 11, and further comprising the liquid photosensitive resin composition 17 on both sides of the substrate 11 A coating film 19 is formed. By holding the upper end of the substrate 11 with the suspension jig 10 in a state where the suspension jig 10 is brought as close to the application roll 12a and the application roll 12b as possible, the application roll of the substrate 11 ( 12a) or winding onto the application roll 12b can be prevented.

Subsequently, the substrate 11 having the coating film 19 formed on both sides is transported to the downstream side of the manufacturing process while being suspended by the suspension jig 10 (FIG. 5). Then, the substrate 11 transferred to the downstream side of the manufacturing process is put into a drying furnace (not shown) and dried. For example, the substrate 11 is transported to a drying furnace in a suspended state. Then, when the substrate 11 passes through the inside of the drying furnace, the substrate 11 is dried.

Inside the drying furnace, hot air from which environmental foreign substances are removed by a filter is blown onto the coating film 19 formed on the substrate 11, for example. Since the support of the substrate 11 is in the form of a film, when drying a plurality of substrates 11 at the same time, if the interval between the substrates 11 is narrow, the substrates 11 are fanned by hot air circulation in the drying furnace. , the substrates 11 are easily attached to each other. Therefore, when drying a plurality of substrates 11 at the same time, it is preferable to make the distance between the substrates 11 larger than the vertical width of the substrates 11 .

The drying temperature of the substrate 11 is preferably 60°C or more and 130°C or less, and more preferably 70°C or more and 120°C or less. Since the organic solvent contained in the liquid photosensitive resin composition 17 can fully be removed by setting the drying temperature of the board|substrate 11 to 60 degreeC or more, adhesion of foreign material etc. to the coating film 19 after drying can be suppressed. . In addition, since the curing reaction of the liquid photosensitive resin composition 17 can be suppressed by setting the drying temperature of the substrate 11 to 130° C. or less, in the photolithography process, which is a post-process, an increase in developing time and the like can be suppressed. can In addition, the drying temperature can be appropriately set depending on the number of charged substrates 11 to the drying furnace and the coating speed.

It is preferable that they are 1 minute or more and 60 minutes or less, and, as for the drying time of the board|substrate 11, it is more preferable that they are 3 minutes or more and 40 minutes or less. Since the organic solvent contained in the liquid photosensitive resin composition 17 can fully be removed by setting drying time to 1 minute or more, adhesion of foreign matter to the coating film 19 after drying, etc. can be suppressed. Moreover, since the hardening reaction of the liquid photosensitive resin composition 17 can be suppressed by making drying time into 60 minutes or less, in the photolithography process which is a post process, the increase of developing time etc. can be suppressed. In addition, the drying time can be appropriately set according to the number of charged substrates 11 to the drying furnace and the coating speed.

Next, an example of the application roll 12a and the application roll 12b is demonstrated. Fig. 6 is a cross-sectional view when the application roll 100, which is an example of the application roll 12a and the application roll 12b, is cut along a plane including its axial center. An application roll 100 shown in FIG. 6 includes a metal core 110 having a cylindrical hollow portion and a surface layer roll 120 arranged on an outer circumferential surface of the core 110 .

The surface layer roll 120 is a roll onto which the liquid photosensitive resin composition 17 (see Fig. 1) is transferred, and is made of, for example, rubber having elasticity in an atmosphere at a temperature of 25°C. The rubber constituting the surface layer roll 120 is not particularly limited, but is preferably one having chemical resistance and abrasion resistance, such as butyl rubber, ethylene propylene rubber, urethane rubber, and nitrile rubber.

In addition, the surface layer roll 120 has a plurality of ring-shaped grooves 120a. Each of the plurality of ring-shaped grooves 120a is independent. The cross-sectional shape of the ring-shaped groove 120a is not particularly limited, and shapes such as a V-shape and a U-shape can be employed. In order to further suppress the appearance defect of the coating film 19 (see Fig. 5) and the appearance defect of the substrate 11 (see Fig. 5) on which the coating film 19 is formed, the cross-sectional shape of the ring-shaped groove 120a is V-shaped. It is desirable to be The pitch P of the ring-shaped grooves 120a is, for example, 500 μm or more and 1000 μm or less. The opening width of the ring-shaped groove 120a is, for example, 500 μm or more and 1000 μm or less. The depth of the ring-shaped groove 120a is, for example, 200 μm or more and 900 μm or less.

What is necessary is just to select the width|variety W of the surface layer roll 120 suitably according to the method which suspends the board|substrate 11 (refer FIG. 1). For example, as shown in FIG. 1 , when holding only the upper end of the substrate 11 with the suspension jig 10, the width W of the surface layer roll 120 is wider than the horizontal width of the substrate 11, Since the coating area of the liquid photosensitive resin composition 17 to the board|substrate 11 can be widened, it is preferable. On the other hand, in the case of gripping both left and right ends of the substrate 11 with a suspension jig (not shown), it is better to make the width W of the surface layer roll 120 narrower than the horizontal width of the substrate 11 for gripping the substrate 11. This is preferable because the margin portion can be easily provided.

The roll diameter D of the application roll 100 is 70 mm or more and 150 mm or less. In order to further suppress the appearance defect of the coating film 19 and the appearance defect of the substrate 11 on which the coating film 19 is formed, the roll diameter D of the coating roll 100 is preferably 80 mm or more and 140 mm or less, and is 90 mm It is more preferable that it is more than 130 mm, and it is more preferable that it is 100 mm or more and 120 mm or less.

Next, elements of the manufacturing method of the flexible printed circuit board according to the present embodiment will be described in detail.

[Film-shaped support]

The film-shaped support is not particularly limited, but from the viewpoints of heat resistance, chemical resistance and dimensional stability, polyimide, polyamide, polyester, polycarbonate, polyarylate, polytetrafluoroethylene, polychlorotrifluoro Selected from the group consisting of ethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene/hexafluoropropylene copolymer, ethylene/tetrafluoroethylene copolymer, and ethylene/chlorotrifluoroethylene copolymer A film-like support containing at least one type of polymer is preferred, and a film-like support containing polyimide is more preferred. The film-shaped support may also contain, for example, additives such as fillers as components other than the polymer. However, in order to obtain a film-like support excellent in flexibility, the polymer content in the film-like support is preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight or more with respect to the total amount of the film-like support. More preferably, it may be 100% by weight.

[Wiring]

The wiring provided on the film-shaped support is not particularly limited, but from the viewpoint of wiring shape stability and wiring refinement, wiring formed by etching electrolytic copper foil or rolled copper foil by a subtractive method, or copper paste or silver paste as a film A wiring formed by screen printing on a shape support is preferred.

[hole]

The hole provided in the substrate is not particularly limited, but from the viewpoint of hole shape stability and interlayer connection reliability, a laser processing machine (more specifically, a processing machine using a carbon dioxide laser, UV laser, YAG laser, excimer laser, etc.) or NC A hole is formed in a flexible copper-clad laminate having a film-shaped support using a drilling machine or the like, and the inside of the hole is subjected to cleaning treatment (desmear treatment) and carbon treatment, followed by copper plating treatment (electrolytic copper plating treatment, electrolytic copper Plating treatment, etc.) is preferred.

[Liquid photosensitive resin composition]

The liquid photosensitive resin composition is not particularly limited, but from the viewpoints of applicability, patterning properties and curability, a binder polymer (hereinafter sometimes referred to as "component (A)"), a photoradical polymerization initiator (hereinafter referred to as "( B) component”), thermosetting resin (hereinafter sometimes referred to as “component (C)”), particles having an average particle diameter of 0.01 μm or more and 100 μm or less (hereinafter “component (D)”) A liquid photosensitive resin composition containing (sometimes described as “component (E)”) and an organic solvent (hereinafter sometimes described as “component (E)”) is preferred.

{component (A)}

As component (A), for example, a polymer that is soluble with respect to component (E) and has a weight average molecular weight in terms of polyethylene glycol of 1,000 or more and 1,000,000 or less can be used. The method for measuring the weight average molecular weight in terms of polyethylene glycol is the same method as or a method similar to that of Examples described later. In addition, "component (A) is soluble in component (E)" means that 5 parts by weight of component (A) was added to 100 parts by weight of component (E), and after stirring at a temperature of 40 ° C. for 1 hour, the temperature This means that the solution cooled to 25°C and left for 24 hours is a solution free from insoluble matter and precipitates.

(A) By making the weight average molecular weight of a component into 1,000 or more, the softness|flexibility and chemical-resistance of the cured film obtained can be improved. Moreover, it can suppress that the viscosity of a liquid photosensitive resin composition becomes large too much because the weight average molecular weight of (A) component shall be 1,000,000 or less.

Specific examples of component (A) include polyurethane-based resins, (meth)acrylic-based resins, polyvinyl-based resins, polystyrene-based resins, polyethylene-based resins, polypropylene-based resins, polyimide-based resins, polyamide-based resins, and polyacetal-based resins. , polycarbonate-based resins, polyester-based resins, polyphenylene ether-based resins, polyphenylene sulfide-based resins, polyether sulfone-based resins, polyether ether ketone-based resins, and the like, these alone or Two or more types can be used in combination.

Among them, at least one kind of polymer selected from the group consisting of a polymer having a urethane bond in one molecule, a polymer having an imide group in one molecule, a polymer having a (meth)acryloyl group in one molecule, and a polymer having a carboxyl group in one molecule It is preferable to use as (A) component.

When a polymer having a urethane bond in one molecule is used as the component (A), while the low resilience and bending resistance of the obtained cured film are improved, the curvature of the cured film tends to be small. In addition, when a polymer having an imide group in one molecule is used as the component (A), the heat resistance, flame retardancy, and electrical insulation reliability of the obtained cured film tend to improve. Moreover, when the polymer which has a (meth)acryloyl group in 1 molecule is used as component (A), while the photosensitivity of a liquid photosensitive resin composition improves, the chemical resistance of the cured film obtained tends to improve. In addition, when a polymer having a carboxyl group in one molecule is used as the component (A), the alkali developability of the liquid photosensitive resin composition is improved, and the adhesion between the obtained cured film and the substrate tends to be improved.

Moreover, the polymer which has multiple types of functional groups in one molecule may be sufficient as (A) component. For example, as component (A), when a polymer having a urethane bond and an imide group in one molecule is used, the low resilience, bending resistance, heat resistance, flame retardancy, and electrical insulation reliability of the cured film obtained are improved, and the warpage of the cured film tends to become smaller. In addition, as component (A), when a polymer having a urethane bond, a carboxy group, and a (meth)acryloyl group in one molecule is used, the photosensitivity and alkali developability of the liquid photosensitive resin composition, the low resilience of the obtained cured film, the bending resistance and While chemical resistance and the adhesiveness of the obtained cured film and a board|substrate improve, there exists a tendency for the curvature of a cured film to become small. Therefore, it is preferable that the polymer which has a urethane bond in 1 molecule further has one or more functional groups selected from the group which consists of an imide group, a carboxy group, and a (meth)acryloyl group.

(Polymer having a urethane bond in one molecule)

"Polymer having a urethane bond in one molecule" means a polymer having at least one urethane bond in one molecule. As a polymer having a urethane bond in one molecule, for example, represented by the following general formula (3), which is a reaction product of a diol compound represented by the following general formula (1) and a diisocyanate compound represented by the following general formula (2) and polymers having repeating units.

In General Formula (1), General Formula (2) and General Formula (3), R ¹ and X ¹ each independently represent a divalent organic group.

Examples of the diol compound represented by the general formula (1) include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 3-butanediol. Methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1, alkylene diols such as 4-cyclohexanediol and 1,4-cyclohexanedimethanol; polyoxyalkylene diols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random copolymers of tetramethylene glycol and neopentyl glycol; Polyesterdiol obtained by reacting a polyhydric alcohol and a polybasic acid; polycarbonate diols having a carbonate skeleton; polycaprolactone diol obtained by subjecting lactones such as γ-butyrolactone, ε-caprolactone, and δ-valerolactone to a ring-opening addition reaction; Bisphenol A, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, hydrogenated bisphenol A, ethylene oxide adduct of hydrogenated bisphenol A, propylene oxide adduct of hydrogenated bisphenol A, etc. A-type compounds etc. are mentioned, These can be used individually or in combination of 2 or more types.

In order to obtain a liquid photosensitive resin composition excellent in roll pressure dispersibility during coating and to improve the low resilience and bending resistance of the obtained cured film, as the diol compound represented by the general formula (1), polyoxyalkylenediol, polyester Long-chain diols such as diols, polycarbonate diols, and polycaprolactone diols are preferred.

Examples of the diisocyanate compound represented by the general formula (2) include diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3 '- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate; 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydi Phenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether -4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, torylene-2,4-diisocyanate, torylene-2,6-di Isocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-[2,2-bis(4-phenoxyphenyl)propane] diisocyanate, hydrogenation Aromatic diisocyanate compounds, such as diphenylmethane diisocyanate and hydrogenated xylylene diisocyanate; alicyclic diisocyanate compounds such as isophorone diisocyanate and norbornene diisocyanate; Aliphatic diisocyanate compounds, such as hexamethylene diisocyanate, trimethyl hexamethylene diisocyanate, and ridine diisocyanate, etc. are mentioned, These can be used individually or in combination of 2 or more types.

In particular, when at least one selected from the group consisting of an alicyclic diisocyanate compound and an aliphatic diisocyanate compound is used as a diisocyanate compound represented by the general formula (2), a liquid photosensitive resin composition having excellent photosensitivity is obtained, so it is preferable. .

When synthesizing a polymer having a urethane bond in one molecule, it is preferable to blend the diol compound and the diisocyanate compound so that the ratio of the number of hydroxyl groups to the number of isocyanate groups is isocyanate group/hydroxyl group = 0.5 or more and 2.0 or less.

In addition, when using two or more types of diol compounds, reaction with a diisocyanate compound may be performed after mixing two or more types of diol compounds, and each diol compound and diisocyanate compound may be reacted separately. Moreover, after making a diol compound and a diisocyanate compound react, you may make the obtained terminal isocyanate compound react with another diol compound, and you may make the reaction material react with another diisocyanate compound. In addition, the case where two or more types of diisocyanate compounds are used is also the same. In this way, a desired polymer having a urethane bond in one molecule can be synthesized.

The reaction temperature of the diol compound and the diisocyanate compound is preferably 40°C or more and 160°C or less, and more preferably 60°C or more and 150°C or less, from the viewpoint of shortening the reaction time and suppressing gelation. The reaction time of the diol compound and the diisocyanate compound can be appropriately selected depending on the amount of starting materials and the reaction conditions employed. Further, if necessary, compounds containing metals or semimetals such as alkali metals, alkaline earth metals, tin, zinc, titanium, and cobalt; You may react in the presence of catalysts, such as tertiary amines.

Although a diol compound and a diisocyanate compound can also be reacted without using a solvent, in order to control reaction, it is preferable to make it react in an organic solvent. Although the organic solvent used here is not specifically limited, For example, the organic solvent mentioned in the specific example of component (E) mentioned later can be used.

In order to increase the reactivity of the polymerization reaction, the amount of the organic solvent used during the reaction is preferably such that the weight concentration of the solute in the reaction solution, that is, the solution concentration is 5% by weight or more and 90% by weight or less. The weight concentration of the solute in the reaction solution is more preferably 10% by weight or more and 80% by weight or less.

The polymer having a urethane bond and a (meth)acryloyl group in one molecule is, for example, in addition to a diol compound and a diisocyanate compound, a compound represented by the following general formula (4) (hereinafter referred to as "compound (4)" A polymerization reaction is performed using at least one selected from the group consisting of a compound represented by general formula (5) (hereinafter sometimes referred to as "compound (5)") and a compound represented by the following general formula (5) as a monomer. obtained by doing

In general formula (4), m represents an integer of 1 or more and 3 or less, R ² represents an m+1 valent organic group, and R ³ represents a hydrogen atom or a methyl group.

In general formula (5), n represents an integer of 1 or more and 3 or less, X ² represents an n+1 valent organic group, and X ³ represents a hydrogen atom or a methyl group.

As compound (4), for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxy Cypropyl (meth)acrylate, 2-hydroxy-1-acryloxy-3-methacryloxypropane, o-phenylphenol glycidyl ether (meth)acrylate, polyethylene glycol mono(meth)acrylate, pentaeryth Lithol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, 1,4-cyclohexanedimethanol mono(meth)acrylate, 4-hydroxyphenyl(meth) Acrylate, 2-(4-hydroxyphenyl)ethyl (meth)acrylate, etc. are mentioned, These can be used individually or in combination of 2 or more types.

Examples of the compound (5) include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and 2-(2-methacrylic acid). Royloxyethyloxy) ethyl isocyanate etc. are mentioned, These can be used individually or in combination of 2 or more types.

A polymer having a urethane bond and a carboxyl group in one molecule is, for example, a compound represented by the following general formula (6) in addition to a diol compound and a diisocyanate compound (hereinafter sometimes referred to as "compound (6)") It is obtained by carrying out a polymerization reaction using as a monomer.

In General Formula (6), R ⁴ represents a trivalent organic group.

As compound (6), for example, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(2-hydroxyethyl)propionic acid, 2,2-bis(3-hydroxypropyl)propionic acid, 2 ,3-dihydroxy-2-methylpropionic acid, 2,2-bis(hydroxymethyl)butanoic acid, 2,2-bis(2-hydroxyethyl)butanoic acid, 2,2-bis(3-hydroxy propyl)butanoic acid, 2,3-dihydroxybutanoic acid, 2,4-dihydroxy-3,3-dimethylbutanoic acid, 2,3-dihydroxyhexadecanoic acid, 2,3-dihydroxybenzoic acid , 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, etc. , These can be used individually or in combination of 2 or more types.

In order to improve the photosensitivity of the liquid photosensitive resin composition, it is preferable to use an aliphatic compound (6).

A polymer having a urethane bond and an imide group in one molecule is obtained, for example, by conducting a polymerization reaction using tetracarboxylic dianhydride as a monomer in addition to a diol compound and a diisocyanate compound.

As tetracarboxylic dianhydride, for example, pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, p-phenylene bis(trimellitate anhydride), 2, 3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3 ,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4 '-(hexafluoroisopropylidene)diphthalic anhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride water, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, and the like; It can be used individually or in combination of 2 or more types.

(Polymer having an imide group in one molecule)

"Polymer having an imide group in one molecule" means a polymer having at least one imide group in one molecule. As a polymer which has an imide group in one molecule, the polymer which has a urethane bond and an imide group in one molecule mentioned above is mentioned, for example. Further, for example, tetracarboxylic dianhydride (more specifically, the compounds exemplified as tetracarboxylic dianhydride for synthesizing a polymer having a urethane bond and an imide group in one molecule described above) and diamine By reacting, a polymer having an imide group in one molecule can also be obtained.

As diamine used as a raw material for obtaining a polymer having an imide group in one molecule, for example, p-phenylenediamine, 4,4'-diaminobenzanilide, 2,2'-bis(trifluoromethyl)benzidine, 9,9-bis(4-aminophenyl)fluorene, 4-aminophenyl-4-aminobenzoate, 1,4-diaminocyclohexane, m-phenylenediamine, 4,4'-oxydianiline, 3 ,4'-oxydianiline, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether, N,N'-bis(4-aminophenyl)terephthalamide, 4,4 '-diaminodiphenylsulfone, m-tolidine, o-tolidine, 4,4'-bis(4-aminophenoxy)biphenyl, 2-(4-aminophenyl)-6-aminobenzoxazole, 3,5-diaminobenzoic acid, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-methylenebis(cyclohexanamine), 1,3-bis(3-aminopropyl ) Tetramethyldisiloxane etc. can be mentioned, These can be used individually or in combination of 2 or more types.

Although it does not specifically limit as a method of making tetracarboxylic acid anhydride and diamine react, For example, the method shown to the following methods 1-3 is mentioned.

Method 1: In a solution obtained by dispersing or dissolving tetracarboxylic dianhydride in an organic solvent, diamine is added and reacted to prepare a polyamic acid solution. It is preferable to adjust the total addition amount of diamine so that it may become a ratio of 0.50 mol or more and 1.50 mol or less with respect to 1 mol of tetracarboxylic dianhydride. After the reaction between tetracarboxylic dianhydride and diamine is completed, the resulting polyamic acid solution is heated to 100°C or more and 300°C or less, more preferably 150°C or more and 250°C or less, to imidize.

Method 2: A polyamic acid solution was prepared in the same manner as in Method 1 above. An imidation catalyst (preferably, a tertiary amine such as pyridine, picoline, isoquinoline, trimethylamine, triethylamine, or tributylamine) and a dehydrating agent (such as acetic anhydride) are added to the prepared polyamic acid solution, Imidization is performed by heating to 60°C or higher and 180°C or lower.

Method 3: A polyamic acid solution was prepared in the same manner as in Method 1 above. The prepared polyamic acid solution is placed in a vacuum oven set at 100°C or higher and 250°C or lower, and heated under reduced pressure to imidize.

(Polymer having a (meth)acryloyl group in one molecule)

"Polymer having a (meth)acryloyl group in one molecule" means a polymer having at least one (meth)acryloyl group in one molecule. As a polymer which has a (meth)acryloyl group in 1 molecule, the polymer which has a urethane bond and a (meth)acryloyl group in 1 molecule mentioned above is mentioned, for example. Moreover, the polymer which has a (meth)acryloyl group in 1 molecule can also be obtained by making an epoxy resin and (meth)acrylic acid react, for example.

As an epoxy resin used as a raw material for obtaining a polymer having a (meth)acryloyl group in one molecule, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin , Biphenyl type epoxy resin, phenoxy type epoxy resin, naphthalene type epoxy resin, phenol novolak type epoxy resin, cresol novolac type epoxy resin, trisphenolmethane type epoxy resin, dicyclopentadiene type epoxy resin, amine type epoxy resin , flexible epoxy resins, urethane-modified epoxy resins, rubber-modified epoxy resins, chelate-modified epoxy resins, heterocycle-containing epoxy resins, and the like, and these may be used alone or in combination of two or more.

As a specific example of the bisphenol A type epoxy resin, Mitsubishi Chemical Corporation brand name jER (registered trademark) 828, jER (registered trademark) 1001, jER (registered trademark) 1002, ADEKA Corporation brand name Adeka Resin (registered trademark) EP-4100E, Adeka Resin (registered trademark) EP-4300E, trade names RE-310S, RE-410S, manufactured by Nippon Kayaku Co., Ltd., trade names manufactured by DIC, Epiclon 840S, Epiclon 850S, Epiclon 1050, Epiclon 7050, manufactured by Nippon-Tsu Epoxy Co., Ltd. trade names EPOTOTO (registered trademark) YD-115, EPOTOTO (registered trademark) YD-127, EPOTOTO (registered trademark) YD-128, and the like.

As a specific example of the bisphenol F-type epoxy resin, trade name jER (registered trademark) 806, jER (registered trademark) 807 manufactured by Mitsubishi Chemical Corporation, trade name Adeka Resin (registered trademark) EP-4901E manufactured by ADEKA, Adeka Resin (registered trademark) EP-4930, Adeka Resin (registered trademark) EP-4950, trade names RE-303S, RE-304S, RE-403S, RE-404S manufactured by Nippon Kayaku Co., Ltd., trade names manufactured by DIC Corporation Epiclone 830, Epiclone 835, Nis Trade names EPOTOTO (registered trademark) YDF-170, EPOTOTO (registered trademark) YDF-175S, EPOTOTO (registered trademark) YDF-2001 and the like available from Tetsu Epoxy Co., Ltd. are exemplified.

As a specific example of a bisphenol S-type epoxy resin, DIC Corporation brand name Epiclon EXA-1514 etc. are mentioned.

As a specific example of hydrogenated bisphenol A type epoxy resin, trade name jER (registered trademark) YX8000 by Mitsubishi Chemical Corporation, jER (registered trademark) YX8034, jER (registered trademark) YL7170, trade name Adeka Resin (registered trademark) EP- by ADEKA Corporation 4080E, trade name Epiclone EXA-7015 manufactured by DIC Corporation, trade name EPOTOTO (registered trademark) YD-3000 manufactured by Nippontsu Epoxy Co., Ltd., EPOTOTO (registered trademark) YD-4000D, and the like.

As a specific example of the biphenyl type epoxy resin, trade name jER (registered trademark) YX4000 by Mitsubishi Chemical Corporation, jER (registered trademark) YL6121H, jER (registered trademark) YL6640, jER (registered trademark) YL6677, trade name NC- by Nippon Kayaku Co., Ltd. 3000, NC-3000H, etc. are mentioned.

As a specific example of a phenoxy-type epoxy resin, the trade name jER (registered trademark) 1256, jER (registered trademark) 4250, jER (registered trademark) 4275 by Mitsubishi Chemical Corporation, etc. are mentioned.

Specific examples of the naphthalene type epoxy resin include Epiclon HP-4032, Epiclon HP-4700, Epiclone HP-4200, manufactured by DIC Corporation, and NC-7000L, manufactured by Nippon Kayaku.

Specific examples of the phenol novolac type epoxy resin include jER (registered trademark) 152 and jER (registered trademark) 154 manufactured by Mitsubishi Chemical Corporation, EPPN (registered trademark) -201-L manufactured by Nippon Kayaku Co., Ltd. and trade name Epi by DIC Corporation. Clone N-740, Epiclon N-770, trade name EPOTOTO (registered trademark) YDPN-638 manufactured by Nippon-Tsu Epoxy Co., Ltd., etc. are mentioned.

Specific examples of the cresol novolak type epoxy resin include EOCN (registered trademark) -1020, EOCN (registered trademark) -102S, EOCN (registered trademark) -103S, EOCN (registered trademark) -104S, manufactured by DIC Corporation, manufactured by Nippon Kayaku Co., Ltd. trade names Epiclone N-660, Epiclone N-670, Epiclone N-680, Epiclone N-695 and the like.

As a specific example of a trisphenolmethane type|mold epoxy resin, Nippon Kayaku Co., Ltd. brand name EPPN (registered trademark) -501H, EPPN (registered trademark) -501HY, EPPN (registered trademark) -502H, etc. are mentioned.

As a specific example of the dicyclopentadiene type epoxy resin, Nippon Kayaku Co., Ltd. product name XD-1000, DIC company product name Epiclon HP-7200, etc. are mentioned.

As specific examples of the amine-type epoxy resin, trade names jER (registered trademark) 604 and jER (registered trademark) 630 manufactured by Mitsubishi Chemical Co., Ltd., trade names Epototo (registered trademark) YH-434 and Epototo (registered trademark) manufactured by Nippon Epoxy Co., Ltd. trademark) YH-434L, trade names TETRAD (registered trademark) -X, TERRAD (registered trademark) -C manufactured by Mitsubishi Gas Chemical Co., Ltd., and the like.

As specific examples of the flexible epoxy resin, trade names jER (registered trademark) 871, jER (registered trademark) 872, jER (registered trademark) YL7175, jER (registered trademark) YL7217 manufactured by Mitsubishi Chemical Corporation, trade name Epiclone EXA-4850 manufactured by DIC Corporation etc. can be mentioned.

Specific examples of the urethane-modified epoxy resin include Adeka Resin (registered trademark) EPU-6, Adeka Resin (registered trademark) EPU-73, and Adeka Resin (registered trademark) EPU-78-11 manufactured by ADEKA. there is.

Specific examples of rubber-modified epoxy resins include Adeka Resin (registered trademark) EPR-4023, Adeka Resin (registered trademark) EPR-4026, and Adeka Resin (registered trademark) EPR-1309, both manufactured by ADEKA.

Specific examples of the chelate-modified epoxy resin include Adeka Resin (registered trademark) EP-49-10, Adeka Resin (registered trademark) EP-49-20, etc., manufactured by ADEKA.

As a specific example of a heterocyclic containing epoxy resin, the brand name TEPIC (trademark) by Nissan Chemical Industries, Ltd., etc. are mentioned.

The method for reacting the epoxy resin and (meth)acrylic acid is not particularly limited, but for example, (meth)acrylic acid and an esterification catalyst (eg, trimethylamine, Reaction by adding a tertiary amine such as triethylamine; a phosphorus compound such as triphenylphosphine; an imidazole compound such as 2-ethyl-4-methylimidazole, etc.) and heating to 40°C or more and 120°C or less can tell you how to do it. The total amount of (meth)acrylic acid added is preferably adjusted to a ratio of 0.1 mol or more and 1.0 mol or less with respect to 1 mol of the epoxy group of the epoxy resin.

(Polymer having a carboxy group in one molecule)

"Polymer having a carboxy group in one molecule" means a polymer having at least one carboxy group in one molecule. As a polymer which has a carboxy group in one molecule, the polymer which has a urethane bond and a carboxy group in one molecule mentioned above is mentioned, for example. Moreover, after making an epoxy resin and (meth)acrylic acid react, for example, the polymer which has a carboxyl group in 1 molecule can also be obtained by further reacting a polybasic acid anhydride.

As a method of obtaining a polymer having a carboxyl group in one molecule by further reacting a polybasic acid anhydride after reacting an epoxy resin with (meth)acrylic acid, for example, after reacting an epoxy resin with (meth)acrylic acid by the method described above, , a method to react by adding a polybasic acid anhydride and heating to 60°C or higher and 150°C or lower. It is preferable to adjust the total addition amount of the polybasic acid anhydride so that the acid value of the obtained solid content is 10 mgKOH/g or more and 160 mgKOH/g or less.

In addition to the above method, a polymer having a carboxy group in one molecule can also be obtained by reacting (meth)acrylic acid with (meth)acrylic acid ester. The method for reacting (meth)acrylic acid and (meth)acrylic acid ester is not particularly limited. For example, a method for radically polymerizing (meth)acrylic acid and (meth)acrylic acid ester in a solvent in the presence of a radical polymerization initiator may be used. can be heard

The (meth)acrylate ester is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate (n-butyl (meth)acrylate), isobutyl (meth)acrylate, ( t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, (meth) Stearyl acrylate, (meth)acrylate benzyl, etc. are mentioned, These can be used individually or in combination of 2 or more types. In order to improve the flexibility and chemical resistance of the cured film of the liquid photosensitive resin composition, as the (meth)acrylic acid ester, from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate and benzyl (meth)acrylate One or more selected types are preferred.

Examples of the radical polymerization initiator include azo compounds such as azobisisobutyronitrile, azobis(2-methylbutyronitrile), and 2,2'-azobis-2,4-dimethylvaleronitrile; organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, dicumyl peroxide, and di-t-butyl peroxide; persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; Hydrogen peroxide etc. are mentioned, These can be used individually or in combination of 2 or more types.

In order to suppress a decrease in the molecular weight of the resulting polymer while increasing the reactivity of the polymerization reaction, the amount of the radical polymerization initiator used is preferably 0.001 parts by weight or more and 5 parts by weight or less, and 0.01 parts by weight, based on 100 parts by weight of the monomers used. It is more preferable that it is above 1 part by weight or less.

In order to increase the reactivity of the polymerization reaction, the amount of the solvent that can be used during the radical polymerization reaction is preferably such that the weight concentration of the solute in the reaction solution, that is, the solution concentration is 5% by weight or more and 90% by weight or less. The weight concentration of the solute in the reaction solution is more preferably 20% by weight or more and 70% by weight or less.

The reaction temperature of the radical polymerization reaction is preferably 20°C or more and 120°C or less, and more preferably 50°C or more and 100°C or less, from the viewpoint of shortening the reaction time and suppressing gelation. The reaction time of the radical polymerization reaction can be appropriately selected depending on the amount of starting materials and the reaction conditions employed.

In order to further suppress the appearance defect of the coating film and the appearance defect of the board|substrate on which the coating film was formed, the content rate of component (A) is preferably 10% by weight or more and 50% by weight or less with respect to the total amount of the liquid photosensitive resin composition, and 20% by weight It is more preferable that it is more than 40 weight% or less.

{component (B)}

Although it does not specifically limit as a component (B), For example, Michler's ketone, 4,4'-bis (diethylamino) benzophenone, 4,4', 4 "-tris (dimethylamino) triphenylmethane, 2 ,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-diimidazole, acetophenone, benzoin, 2-methylbenzoin, benzoin methyl ether , benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-t-butyl anthraquinone, 1,2-benzo-9,10-anthraquinone, methyl anthraquinone, thioxanthone, 2,4 -Diethylthioxanthone, 2-isopropylthioxanthone, 1-hydroxycyclohexylphenylketone, diacetylbenzyl, benzyldimethylketal, benzyldiethylketal, 4,4'-diazidechalcone, 2,2- Dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]- 2-Hydroxy-2-methyl-1-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2- Dimethylamino-1-(4-morpholinophenyl)-butanone-1, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4 , 4-trimethylpentylphosphine oxide, (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate and the like; , These can be used individually or in combination of 2 or more types.

In order to enhance the reactivity and resolution of photoradical polymerization, the content of component (B) is preferably 0.5% by weight or more and 5% by weight or less, and more preferably 0.8% by weight or more and 4% by weight or less with respect to the total amount of the liquid photosensitive resin composition. desirable.

{Component (C)}

Although it does not specifically limit as component (C), For example, epoxy resin, oxetane resin, phenol resin, isocyanate resin, block isocyanate resin, bismaleimide resin, bisallyl nadimide resin, polyester resin (for example, unsaturated polyester resins, etc.), diallyl phthalate resins, silicon resins, vinyl ester resins, melamine resins, polybismaleimidetriazine resins (BT resins), cyanate resins (eg cyanate ester resins, etc.), urea Resins, guanamine resins, sulfoamide resins, aniline resins, polyurea resins, thiourethane resins, polyazomethine resins, episulfide resins, benzoxazine resins, copolymer resins thereof, modified resins obtained by modifying these resins, Mixtures of these resins or with other resins are exemplified.

In order to impart adhesiveness to conductors such as metal foil or circuit boards while imparting heat resistance to the resulting cured film, as the component (C), an epoxy resin is preferable, and a polyfunctional epoxy resin is more preferable. A "multifunctional epoxy resin" refers to a compound containing at least two epoxy groups in one molecule. Although it does not specifically limit as a polyfunctional epoxy resin, For example, what was mentioned as a specific example of the said "epoxy resin used as a raw material for obtaining the polymer which has a (meth)acryloyl group in one molecule" can be used.

The curing agent of component (C) may be contained in the liquid photosensitive resin composition. Although it does not specifically limit as a hardening|curing agent of component (C), For example, Phenol resins, such as a phenol novolak resin, a cresol novolac resin, and a naphthalene type phenol resin; amino resins; urea resin; melamine; Dicyandiamide etc. are mentioned, These can be used individually or in combination of 2 or more types.

The curing accelerator of component (C) may be contained in the liquid photosensitive resin composition. Although it does not specifically limit as a hardening accelerator of (C) component, For example, phosphine type compounds, such as triphenylphosphine; tertiary amines; alcohol amine compounds such as trimethanolamine and triethanolamine; borate-based compounds such as 1,8-diazabicyclo[5,4,0]-7-undecenium tetraphenylborate; Imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-hepta imidazole-based compounds such as decylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, and 2-phenyl-4-methylimidazole; 2-methylimidazoline, 2-ethylimidazoline, 2-isopropylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2,4-dimethylimidazoline, 2-phenyl- imidazoline-based compounds such as 4-methylimidazoline; 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, 2,4-diamino-6-[2-(2- Undecyl-1-imidazolyl) ethyl] -1,3,5-triazine, 2,4-diamino-6- (2'-ethyl-4'-methylimidazolyl) ethyl-1,3, Triazine type compounds, such as 5-triazine, etc. are mentioned, These can be used individually or in combination of 2 or more types.

Further, as component (A), for example, when a polymer having an acid value of 10 mgKOH/g or more (preferably a polymer having an acid value of 10 mgKOH/g or more and 160 mgKOH/g or less) is used, component (C) It is not necessary to mix the curing agent and curing accelerator in the liquid photosensitive resin composition. The acid value of component (A) can be adjusted, for example, by changing the charged amount of a monomer having one or more groups selected from the group consisting of a carboxyl group and a carboxylic acid anhydride group when synthesizing component (A).

In order to improve the flexibility and chemical resistance of the resulting cured film, the content of component (C) is preferably 1% by weight or more and 10% by weight or less, and more preferably 3% by weight or more and 8% by weight or less with respect to the total amount of the liquid photosensitive resin composition. desirable.

{Component (D)}

Component (D) is not particularly limited as long as it is a particle having an average particle diameter of 0.01 μm or more and 100 μm or less, and one or more types of particles selected from the group consisting of inorganic particles and organic particles can be used, for example. (D) The viscosity and thixotropy of a liquid photosensitive resin composition can be adjusted by mix|blending component (D) with a liquid photosensitive resin composition.

In order to improve the flexibility and chemical resistance of the resulting cured film while enhancing the resolution of the liquid photosensitive resin composition, the average particle diameter of component (D) is preferably 0.01 μm or more and 50 μm or less, and more preferably 0.01 μm or more and 10 μm or less. desirable.

Specific examples of component (D) include inorganic particles such as silica, mica, talc, clay, barium titanate, barium sulfate, wollastonite, calcium carbonate, magnesium carbonate, aluminum oxide, titanium oxide, silicon nitride, and aluminum nitride; and organic particles such as core-shell rubber and crosslinked polymer, and these may be used alone or in combination of two or more.

As the inorganic particles, silica particles are preferable from the viewpoint of increasing the hardness and adhesion of the obtained cured film while suppressing cure shrinkage of the obtained cured film. Examples of silica particles include fused silica particles, crushed silica particles, spherical silica particles, crystalline silica particles, and fumed silica particles.

As the organic particles, crosslinked polymer particles are preferable, and crosslinked polymer particles having an average particle diameter of 1 μm or more and 10 μm or less are more preferable from the viewpoint of improving the flexibility and chemical resistance of the obtained cured film while increasing the dispersibility of the roll pressure during coating. , crosslinked polymer particles having an average particle diameter of 1 µm or more and 5 µm or less are more preferred. As specific examples of the crosslinked polymer particles, trade name Dynamic Beads (registered trademark) UCN-8070CM Clear, UCN-8150CM Clear, UCN-5070D Clear, UCN-5150D Clear, trade name Art Pearl (manufactured by Dainichi Seika Kogyo Co., Ltd.), manufactured by Negami Kogyo Co., Ltd. registered trademark) C-100 Clear, C-200 Clear, C-300 Clear, C-300WA, C-400 Clear, C-400WA, C-600 Clear, C-800 Clear, C-800WA, C-1000T, P -400T, P-800T, U-600T, CF-600T, JB-400T, JB-800T, CE-400T, CE-800T, MM-120T and the like, these alone or in combination of two or more and can be used.

In order to further increase the flexibility of the obtained cured film, it is preferable to use polyurethane particles as component (D). In addition, in order to further increase the flexibility of the obtained cured film while increasing the dispersibility of the roll pressure during coating, it is preferable to use crosslinked polyurethane particles that are crosslinked polymer particles as component (D).

In order to further suppress the appearance defects of the coating film and the appearance defects of the substrate on which the coating film is formed, the content of component (D) is preferably 5 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of component (A), 5 It is more preferably 80 parts by weight or more, more preferably 10 parts by weight or more and 80 parts by weight or less, and even more preferably 20 parts by weight or more and 80 parts by weight or less.

{Component (E)}

(E) component is a component used in order to adjust the viscosity of a liquid photosensitive resin composition. (E) As a component, For example, Sulfoxide solvents, such as dimethyl sulfoxide and diethyl sulfoxide; formamide solvents such as N,N-dimethylformamide and N,N-diethylformamide; acetamide-based solvents such as N,N-dimethylacetamide and N,N-diethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; hexamethylphosphoramide; (gamma)-butyrolactone etc. are mentioned. Further, if necessary, these organic solvents and aromatic hydrocarbons (more specifically, xylene, toluene, etc.) may be used in combination.

Further, as component (E), 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, bis[2-(2-methoxyethoxyethyl)] ether, 1,2-diethoxyethane, symmetrical glycol diether solvents such as bis(2-ethoxyethyl) ether and bis(2-butoxyethyl) ether; Methyl acetate, ethyl acetate, isopropyl acetate, n-propyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 3- acetate solvents such as methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol diacetate, and 1,3-butylene glycol diacetate; Dipropylene glycol methyl ether, tripropylene glycol methyl ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl ether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-propyl ether, Propylene glycol phenyl ether, dipropylene glycol dimethyl ether, 1,3-dioxolane, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, ethylene glycol monoethyl ether , ether solvents such as triethylene glycol dimethyl ether can also be used.

In order to easily adjust the viscosity ratio over time of the liquid photosensitive resin composition to 1.20 or less, it is preferable to use a water-soluble organic solvent having a boiling point of 180°C or higher as the component (E). A water-soluble organic solvent with a boiling point of 180 ° C. or higher is difficult to volatilize and the change in viscosity due to moisture absorption is relatively small. Therefore, when a water-soluble organic solvent with a boiling point of 180 ° C. or higher is used as component (E), a vertical suspension roll coater can be used continuously for a long time. Even if it is operated as, the viscosity change of the liquid photosensitive resin composition becomes relatively small. In order to shorten the drying time of the coating film, it is preferable that the boiling point of component (E) is 250°C or less.

In addition, "a water-soluble organic solvent having a boiling point of 180 ° C. or higher" means a mixed liquid having a boiling point of 180 ° C. or higher at 1 atm and when the flow subsides after gently mixing with pure water of the same volume at a temperature of 20 ° C. at 1 atm. It refers to an organic solvent that maintains this uniform appearance.

Examples of the water-soluble organic solvent having a boiling point of 180° C. or higher include triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol methyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diethylene glycol diethyl ether. ethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and the like, and these It can be used individually or in combination of 2 or more types.

In order to easily adjust the viscosity of the liquid photosensitive resin composition to a range suitable for coating, the content of component (E) is preferably 10% by weight or more and 80% by weight or less, and 20% by weight or more with respect to the total amount of the liquid photosensitive resin composition. It is more preferable that it is 70 weight% or less.

{other ingredients}

The liquid photosensitive resin composition, if necessary, as other components (components (A) to (E) and other components), radical polymerizable compounds, flame retardants, antifoaming agents, leveling agents, colorants, adhesive aids, polymerization inhibitors, etc. You may contain various additives of. The total content of the other components is, for example, 20% by weight or less, preferably 10% by weight or less, based on the total amount of the liquid photosensitive resin composition.

A radically polymerizable compound refers to a compound containing in one molecule a radically polymerizable group in which a polymerization reaction proceeds with a radical polymerization initiator. As the radical polymerizable compound, a compound having a molecular weight (in the case of a polymer, a weight average molecular weight) of less than 1,000 is preferable. Especially, the compound which has at least one unsaturated double bond in 1 molecule is preferable, and the compound which has at least one group selected from the group which consists of a (meth)acryloyl group and a vinyl group is more preferable.

(A) When component does not have a (meth)acryloyl group, it is preferable that a liquid photosensitive resin composition contains a radically polymerizable compound as a component capable of radical photopolymerization. That is, it is preferable that the liquid photosensitive resin composition contains the (A) component which has a (meth)acryloyl group, or contains a radically polymerizable compound as another component. Moreover, in order to improve the reactivity of radical photopolymerization even if (A) component has a (meth)acryloyl group, it is preferable that the liquid photosensitive resin composition contains a radically polymerizable compound.

Hereinafter, specific examples of radically polymerizable compounds are given. In addition, ethylene oxide is described as "EO" below. In addition, the average added mole number of EO is described as "n". As specific examples of the radically polymerizable compound, EO modified bisphenol F diacrylate (n: 2 or more and 50 or less), EO modified bisphenol A diacrylate (n: 2 or more and 50 or less), EO modified bisphenol S diacrylate (n: 2 or more and 50 or less), EO modified bisphenol F dimethacrylate (n: 2 or more and 50 or less), EO modified bisphenol A dimethacrylate (n: 2 or more and 50 or less), EO modified bisphenol S dimethacrylate (n : 2 or more and 50 or less), 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate , dipentaerythritol hexaacrylate, tetramethylolpropane tetraacrylate, tetraethylene glycol diacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol dimethacrylate , trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethacrylate, tetramethylolpropane tetramethacrylate, tetraethylene glycol dimethacrylate, methoxydiethylene glycol methacrylate , methoxy polyethylene glycol methacrylate, 3-chloro-2-hydroxypropyl methacrylate, stearyl methacrylate, phenoxyethyl acrylate, phenoxy diethylene glycol acrylate, phenoxy polyethylene glycol acrylate, lauryl Acrylates, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexane Diol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane trimethacrylate, Tetramethylolmethane triacrylate, methoxy dipropylene glycol methacrylate, methoxy triethylene glycol acrylate, nonylphenoxy polyethylene glycol acrylate, nonylphenoxy polypropylene glycol acrylate, Isostearyl acrylate, nonylphenoxyethylene glycol acrylate, 1,4-butanediol dimethacrylate, 3-methyl-1,5-pentanediol dimethacrylate, 1,9-nonanediol methacrylate, 2 ,4-diethyl-1,5-pentanediol dimethacrylate, dipropylene glycol diacrylate, 2,4-diethyl-1,5-pentanediol diacrylate, ditrimethylolpropane tetraacrylate, di Pentaerythritol polyacrylate, isocyanurate triallyl, glycidyl methacrylate, glycidyl allyl ether, triallyl 1,3,5-benzenecarboxylate, triallylamine, triallyl phosphate, diallyl Amine, diallyldimethylsilane, diallyl disulfide, diallyl ether, diallyl isophthalate, diallyl terephthalate, 1,3-diallyloxy-2-propanol, 4,4'-isopropylidenediphenol dimetha A acrylate, 4,4'- isopropylidene diphenol diacrylate, etc. are mentioned, These can be used individually or in combination of 2 or more types.

In order to increase the solubility of the liquid photosensitive resin composition in an aqueous developing solution and shorten the development time, as the radically polymerizable compound, EO-modified bisphenol F diacrylate (n: 2 or more and 50 or less), EO-modified bisphenol A diacrylate ( n: 2 or more and 50 or less), EO modified bisphenol S diacrylate (n: 2 or more and 50 or less), EO modified bisphenol F dimethacrylate (n: 2 or more and 50 or less), EO modified bisphenol A dimethacrylate ( n: 2 or more and 50 or less) and EO-modified bisphenol S dimethacrylate (n: 2 or more and 50 or less) at least one selected from the group consisting of is preferred.

In order to increase the solubility of the liquid photosensitive resin composition in an aqueous developer while enhancing the radical polymerization reactivity of the liquid photosensitive resin composition, the content rate of the radical polymerizable compound is 1% by weight or more and 10% by weight or less with respect to the total amount of the liquid photosensitive resin composition. it is desirable

Examples of the flame retardant include halogen-based flame retardants, phosphorus-based flame retardants, metal hydroxides, and antimony-based flame retardants.

A halogen-based flame retardant refers to a compound that contains at least one halogen atom in one molecule and suppresses combustion of organic substances. Examples of the halogen-based flame retardant include bromine-based compounds and chlorine-based compounds, and these may be used alone or in combination of two or more.

A phosphorus-based flame retardant refers to a compound that contains at least one phosphorus atom in one molecule and suppresses combustion of organic substances. Examples of the phosphorus-based flame retardant include red phosphorus, condensed phosphate ester-based compounds, cyclic organic phosphorus-based compounds, phosphazene-based compounds, phosphorus-containing polyol-based compounds, phosphorus-containing amine-based compounds, ammonium polyphosphate, melamine phosphate, and phosphinic acid salts. These can be used alone or in combination of two or more.

As a metal hydroxide which functions as a flame retardant, aluminum hydroxide, magnesium hydroxide, etc. are mentioned, for example, These can be used individually or in combination of 2 or more types.

An antimony-based flame retardant refers to a compound that contains at least one antimony atom in one molecule and suppresses combustion of organic substances. As an antimony flame retardant, antimony trioxide is mentioned, for example.

As an antifoamer, an acryl-type compound, a vinyl-type compound, a butadiene-type compound etc. are mentioned, for example.

As a leveling agent, an acrylic compound, a vinyl type compound, etc. are mentioned, for example.

As a coloring agent, a phthalocyanine type compound, an azo type compound, carbon black etc. are mentioned, for example.

Examples of the adhesive aid (also referred to as an adhesion imparting agent) include silane coupling agents, triazole-based compounds, tetrazole-based compounds, and triazine-based compounds.

As a polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, etc. are mentioned, for example.

[Preparation method of liquid photosensitive resin composition]

The liquid photosensitive resin composition can be prepared, for example, by pulverizing and dispersing the above components (A) to (E) and other components used as necessary and mixing them. Although it does not specifically limit as a grinding|pulverization / dispersion method, For example, the method of using a kneading apparatus, such as a bead mill, a ball mill, and a 3-roll mill, is mentioned. Among them, the method of pulverizing and dispersing using a three-roll mill and mixing is preferable because the particle size distribution becomes uniform.

[Random process]

In this embodiment, it is an arbitrary process including the process of drying the board|substrate mentioned above (drying process) other than the process of apply|coating the liquid photosensitive resin composition. As an arbitrary process, the fine opening formation process and hardening process shown below other than a drying process are mentioned, for example.

(Fine opening formation process)

Active energy rays (more specifically, ultraviolet rays, visible rays, electron beams, etc.) are irradiated to the coating film after the drying step through a negative photomask to expose a part of the coating film. As a result, the component capable of photo-radical polymerization is polymerized in the exposed portion of the coating film. Next, the unexposed portion is washed with a developing solution using a developing method such as spray, paddle, immersion, and ultrasonic waves, thereby patterning the coating film and forming fine openings. In addition, since the time until opening differs depending on the spray pressure and flow rate of the developing device and the temperature of the developing solution, it is desirable to appropriately determine the optimal device conditions.

As a developing solution, alkaline aqueous solution is preferable. The developing solution may contain a water-soluble organic solvent such as methanol, ethanol, 1-propanol, 2-propanol, or N-methyl-2-pyrrolidone. Examples of the alkaline compound contained in the alkaline aqueous solution include hydroxides, carbonates or hydrogencarbonates of alkali metals, alkaline earth metals or ammonium ions, amine compounds, etc. Specifically, sodium hydroxide, potassium hydroxide, hydroxide Ammonium, Sodium Carbonate, Potassium Carbonate, Ammonium Carbonate, Sodium Bicarbonate, Potassium Bicarbonate, Ammonium Bicarbonate, Tetramethylammonium Hydroxide, Tetraethylammonium Hydroxide, Tetrapropylammonium Hydroxide, Tetraisopropylammonium Hydroxide , N-methyldiethanolamine, N-ethyldiethanolamine, N,N-dimethylethanolamine, triethanolamine, triisopropylamine, etc., and compounds other than these can be used as long as the aqueous solution is basic. there is. The concentration of the alkaline compound in the alkaline aqueous solution is preferably 0.01% by weight or more and 20% by weight or less, more preferably 0.02% by weight or more and 10% by weight or less. The temperature of the developing solution depends on the composition of the liquid photosensitive resin composition and the composition of the alkaline developing solution, but is generally 0°C or more and 80°C or less, preferably 10°C or more and 60°C or less.

It is preferable to clean the inside of the micro-openings formed by development to remove unnecessary residues. As the cleaning liquid, water, acidic aqueous solution, and the like are exemplified.

(curing process)

Next, heat treatment is performed on the coating film (patterned coating film) in which fine openings are formed. A cured film with high heat resistance can be obtained by performing heat treatment and reacting the reactive groups remaining in the molecular structure constituting the coating film (for example, the reactive groups of component (C), etc.). Through the above process, a flexible printed circuit board is obtained. The thickness of the cured film is determined in consideration of the thickness of wiring and the like, but is preferably 2 μm or more and 50 μm or less. The final curing temperature in the curing step is preferably low for the purpose of preventing oxidation of the wiring or the like and not reducing the adhesion between the wiring and the film-shaped support. The final curing temperature is preferably 100°C or higher and 250°C or lower, more preferably 120°C or higher and 200°C or lower, still more preferably 130°C or higher and 180°C or lower. The curing time at the final curing temperature is, for example, 1 minute or more and 120 minutes or less. The cured film formed according to the present embodiment tends to have small warpage after the curing step while being excellent in flexibility, flame retardancy and electrical insulation reliability. Therefore, the cured film formed according to this embodiment is particularly suitable as an insulating material for a flexible printed circuit board.

Example

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited only to these examples.

First, a method for measuring the weight average molecular weight and acid value of the binder polymers P1 to P4 and the solid content concentration of the resin solutions SP1 to SP4 each containing the binder polymers P1 to P4 will be described.

<Measurement method of weight average molecular weight>

The weight average molecular weights of the binder polymers P1 to P4 were measured under the following conditions.

Device used: Tosoh Corporation "HLC-8220GPC"

Column: Tosoh Corporation "TSKgel Super AWM-H" (6.0mmI.D. × 15cm) × 2

・Guard column: Tosoh Corporation “TSKguardcolumn Super AW-H” × 1

Eluent: N,N-dimethylformamide solution in which LiBr (concentration: 30mmol/L) and H ₃ PO ₄ (concentration: 20mmol/L) are dissolved

· Flow rate: 0.6mL/min

· Column temperature: 40 ℃

Detector: RI (Differential Refractometer)

RI detection conditions: polarity (+), response (0.5 sec)

Sample concentration: 5 mg/mL

Standard product: PEG (polyethylene glycol)

<Acid value measurement method>

The acid values of the binder polymers P1 to P4 were measured by the method described in JIS K 5601-2-1 (1999).

<Method for Measuring Solid Concentration of Resin Solution>

Solid content concentrations of the resin solutions SP1 to SP4 were measured by the method described in JIS K 5601-1-2 (2008). Drying conditions at the time of measurement were 170 degreeC x 1 hour.

<Preparation of resin solution>

Hereinafter, a method for preparing resin solutions SP1 to SP4 each containing binder polymers P1 to P4 as component (A) will be described. In addition, in the following, the reaction (stirring) was performed under a nitrogen stream unless otherwise specified.

[Preparation of Resin Solution SP1 Containing Binder Polymer P1]

In a reaction vessel equipped with a stirrer, a thermometer and a nitrogen inlet tube, 35.00 g of triethylene glycol dimethyl ether (hereinafter sometimes referred to as "TEGDM") as a polymerization solvent and 10.31 g (0.050 mol) of norbornene diisocyanate was added, and the contents of the container were heated to 80° C. while stirring under a nitrogen stream to dissolve norbornene diisocyanate in TEGDM. Next, to the contents of the container, a TEGDM solution of polycarbonate diol (“PCDL T5652” manufactured by Asahi Kasei Co., Ltd., weight average molecular weight: 2,000) was added over 1 hour, and then the obtained solution was stirred for 2 hours while heating to 80 ° C. did. In addition, the polycarbonate diol TEGDM solution was a solution obtained by dissolving 50.00 g (0.025 mol) of polycarbonate diol in 35.00 g of TEGDM. Next, 15.51 g (0.050 mol) of 4,4'-oxydiphthalic anhydride was added to the contents of the vessel, and the contents of the vessel were stirred for 1 hour while being heated to 190°C. Then, after cooling the container contents to 80 degreeC, 3.60 g (0.200 mol) of pure water was added to the container contents. Then, the contents of the container were refluxed for 5 hours while heating to 110°C to obtain a resin solution SP1 containing a binder polymer P1 having a urethane bond and an imide group in one molecule. Solid content concentration of obtained resin solution SP1 was 53 weight%. In addition, the weight average molecular weight and acid value of binder polymer P1 were 9,200 and 86 mgKOH/g, respectively.

[Preparation of Resin Solution SP2 Containing Binder Polymer P2]

40.00 g of TEGDM as a polymerization solvent and 20.62 g (0.100 mol) of norbornene diisocyanate were added to a reaction vessel equipped with a stirrer, a thermometer, and a nitrogen inlet tube, and the contents of the vessel were heated to 80° C. while stirring under a nitrogen stream. , norbornenediisocyanate was dissolved in TEGDM. Next, to the contents of the container, polycarbonate diol (“PCDL T5652” manufactured by Asahi Kasei Co., Ltd., weight average molecular weight: 2,000), 2,2-bis(hydroxymethyl)butanoic acid and 2-hydroxyethyl methacrylate The TEGDM solution was added over 1 hour. The obtained solution was stirred for 5 hours while heating at 80°C to obtain resin solution SP2 containing binder polymer P2 having a urethane bond, a carboxy group and a methacryloyl group in one molecule. In addition, the TEGDM solution of the polycarbonate diol, 2,2-bis (hydroxymethyl) butanoic acid and 2-hydroxyethyl methacrylate, polycarbonate diol 50.00g (0.025 mol) and 2,2 - It was a solution in which 3.70 g (0.025 mol) of bis(hydroxymethyl)butanoic acid and 13.02 g (0.100 mol) of 2-hydroxyethyl methacrylate were dissolved in 40.00 g of TEGDM. The solid content concentration of obtained resin solution SP2 was 52 weight%. In addition, the weight average molecular weight and acid value of binder polymer P2 were 8,600 and 18 mgKOH/g, respectively.

[Preparation of Resin Solution SP3 Containing Binder Polymer P3]

100.00 g of TEGDM as a polymerization solvent was charged into a reaction vessel equipped with a stirrer, a thermometer and a nitrogen inlet tube, and the temperature of the contents of the vessel was raised to 80°C while stirring under a nitrogen stream. Then, the mixture containing the methacrylic acid compound was added dropwise to the reaction container over 3 hours using a dropping funnel while maintaining the temperature of the contents of the container at 80°C. In addition, the mixture containing the said methacrylic acid compound is 12.0 g (0.14 mol) of methacrylic acid, 28.0 g (0.16 mol) of benzyl methacrylate, and 60.0 butyl methacrylate which were previously mixed in the atmosphere of the temperature of 25 degreeC. g (0.42 mol) and 0.5 g of azobisisobutyronitrile as a radical polymerization initiator. After completion of the dropping, the temperature was raised to 90°C while stirring the contents of the container. Then, the contents of the container were stirred for 2 hours while the temperature of the contents of the container was maintained at 90°C, and resin solution SP3 containing binder polymer P3 having a carboxy group in one molecule was obtained. Solid content concentration of obtained resin solution SP3 was 50 weight%. In addition, the weight average molecular weight and acid value of binder polymer P3 were 48,000 and 78 mgKOH/g, respectively.

[Preparation of Resin Solution SP4 Containing Binder Polymer P4]

In a reaction vessel equipped with a stirrer, a thermometer and a nitrogen inlet pipe, 35.00 g of diethylene glycol diethyl ether (hereinafter sometimes referred to as “DEGDE”) as a polymerization solvent and 10.31 g (0.050 mol) of norbornene diisocyanate ) was added, and the contents of the container were heated to 80° C. while stirring under a nitrogen stream to dissolve norbornene diisocyanate in DEGDE. Next, after adding a DEGDE solution of polycarbonate diol (“PCDL T5652” manufactured by Asahi Kasei, weight average molecular weight: 2,000) to the contents of the container over 1 hour, the obtained solution was stirred for 2 hours while heating to 80°C. In addition, the DEGDE solution of the said polycarbonate diol was a solution which melt|dissolved 50.00 g (0.025 mol) of polycarbonate diol in 35.00 g of DEGDE. Next, 26.02 g (0.050 mol) of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride was added to the contents of the vessel, and the contents of the vessel were stirred for 1 hour while heating to 190°C. . Then, after cooling the container contents to 80 degreeC, 3.60 g (0.200 mol) of pure water was added to the container contents. Then, the contents of the container were refluxed for 5 hours while heating to 110°C, and resin solution SP4 containing binder polymer P4 having a urethane bond and an imide group in one molecule was obtained. Solid content concentration of obtained resin solution SP4 was 55 weight%. In addition, the weight average molecular weight and acid value of binder polymer P4 were 5,500 and 90 mgKOH/g, respectively.

<Preparation of liquid photosensitive resin composition>

Any of the resin solutions SP1 to SP4 obtained by the preparation method described above and each component listed in Tables 1 to 7 described later (specifically, components other than component (A)) are mixed with a stirring device equipped with a stirring blade. did. Next, after passing the obtained mixture twice through three roll mills, it was defoamed with a defoaming device to obtain liquid photosensitive resin compositions used in Examples 1 to 25 and Comparative Examples 1 to 8, respectively. Moreover, when the average particle diameter of the particle|grains in the obtained liquid photosensitive resin composition was measured, it was 10 micrometers or less also in any of Examples 1-25 and Comparative Examples 1-8.

<Method for Measuring Physical Properties of Liquid Photosensitive Resin Composition and Evaluation Method for Liquid Photosensitive Resin Composition>

[Viscosity measurement method]

The viscosity of each liquid photosensitive resin composition (the viscosity described in Tables 1 to 7 described later) was measured under the following conditions using a Brookfield rotational viscometer ("HBDV-I" manufactured by Brookfield), and measured ( Rotation) It was set as the viscosity shown by the Brookfield type rotational viscometer 3 minutes after the start. Hereinafter, the viscosity measured here may be described as "V ₅₀ ".

Spindle: No.3

・Measurement temperature: 25℃

Rotation speed: 50rpm

[Measurement method of TI value]

For each liquid photosensitive resin composition, except that the rotation speed was changed to 5 rpm, the measurement was started under the same conditions as in [Viscosity Measurement Method], and 3 minutes after the start of measurement (rotation), a Brookfield rotational viscometer The TI value was calculated from the indicated viscosity and the above V ₅₀ .

[Measurement method of viscosity ratio over time]

For each liquid photosensitive resin composition, the measurement was started under the same conditions as in the [Method for Measuring Viscosity], and the viscosity shown by the Brookfield rotational viscometer 24 hours after the start of the measurement (rotation) and the viscosity ratio over time from the above V ₅₀ Calculated.

[Method for measuring elastic modulus of cured film]

Each liquid photosensitive resin composition was applied to a part (an area of 200 mm x 200 mm area) on a polytetrafluoroethylene sheet having a thickness of 25 µm using a Baker's applicator. At this time, the coating amount of the liquid photosensitive resin composition was adjusted so that the thickness of the cured film might be 20 μm. Next, after drying the coating film containing the liquid photosensitive resin composition under the conditions of a drying temperature of 80° C. and a drying time of 20 minutes, the entire surface of the coating film was irradiated with ultraviolet rays under the conditions of a cumulative exposure amount of 300 mJ/cm 2 and exposed. Subsequently, spray development was performed for 90 seconds under conditions of a discharge pressure of 1.0 kgf/mm 2 to the coated film after exposure using a 1.0% by weight aqueous solution of sodium carbonate (temperature: 30° C.) as a developing solution. Next, after washing the developed coating film with pure water, it was heated in an oven at a temperature of 150°C for 60 minutes to form a cured film of the liquid photosensitive resin composition on the sheet made of polytetrafluoroethylene. Then, the formed cured film was peeled off from the sheet made of polytetrafluoroethylene and cut into a size of 200 mm in length and 15 mm in width to obtain a test piece having a thickness of 20 μm. The elastic modulus of the cured film was measured under the following conditions using the obtained test piece.

Device used: Tensile tester (“Autograph S type” manufactured by Shimadzu Corporation)

・Measurement temperature: 23℃

· Tensile speed: 50 mm / min

[Evaluation method of fine porosity]

Each liquid photosensitive resin composition was applied onto a part (area of 200 mm × 200 mm in area) of a polyimide film (“Apical (registered trademark) 25NPI” manufactured by Kaneka Corporation) having a thickness of 25 μm using a Baker-style applicator. . At this time, the coating amount of the liquid photosensitive resin composition was adjusted so that the thickness of the cured film might be 20 μm. Then, after drying the coating film containing the liquid photosensitive resin composition under conditions of a drying temperature of 80° C. and a drying time of 20 minutes, a diameter of 30 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm and 200 μm Through a negative photomask having a circular light-shielding region, the coating film was irradiated with ultraviolet rays and exposed under conditions of a cumulative exposure amount of 300 mJ/cm 2 . Subsequently, spray development was performed for 90 seconds under conditions of a discharge pressure of 1.0 kgf/mm 2 to the coated film after exposure using a 1.0% by weight aqueous solution of sodium carbonate (temperature: 30° C.) as a developing solution. Next, after washing the developed coating film with pure water, it was heated in an oven at a temperature of 150°C for 60 minutes to form a cured film of the liquid photosensitive resin composition on the polyimide film. The obtained cured film was observed with an optical microscope, and the smallest diameter among the holes formed was used as the evaluation value of fine opening properties.

[Method of measuring repulsive force]

First, an electrolytic copper foil (thickness: 12 μm) is bonded to both sides of a polyimide film ("Pixio (registered trademark) BP FRS-522#SW" manufactured by Kaneka Corporation, thickness: 12.5 μm) as a film-shaped support. Flexible copper foil Laminates were prepared. The copper foil on one side of this flexible copper-clad laminate was patterned to form a comb-shaped pattern with line width/space width = 100 µm/100 µm on the film-shaped support. Next, the laminated board on which the comb-shaped pattern was formed was immersed in a 10% by volume sulfuric acid aqueous solution for 1 minute, and then washed with pure water. Next, each liquid photosensitive resin composition was applied on the comb-shaped pattern using a Baker-style applicator. At this time, the coating amount of the liquid photosensitive resin composition was adjusted so that the thickness of the cured film on the comb pattern would be 20 μm. Next, after drying the coating film containing the liquid photosensitive resin composition under the conditions of a drying temperature of 80° C. and a drying time of 20 minutes, the entire surface of the coating film was irradiated with ultraviolet rays under the conditions of a cumulative exposure amount of 300 mJ/cm 2 and exposed. Subsequently, spray development was performed for 90 seconds under the condition of a discharge pressure of 1.0 kgf/mm 2 to the coated film after exposure, using a 1.0% by weight aqueous solution of sodium carbonate (temperature: 30° C.) as a developing solution. Next, after washing the developed coating film with pure water, it was heated in an oven at a temperature of 150°C for 60 minutes to form a cured film of the liquid photosensitive resin composition on the comb pattern. Next, the laminated body containing the obtained cured film was cut into a size of 15 mm in width x 200 mm in length to obtain a test piece. This test piece was rounded into a loop shape with an outer circumference of 50 mm and fixed to a repulsive force measuring device (“Loop Stiffness Tester (registered trademark)” manufactured by Toyo Seiki Seisakusho), and the test piece rounded into a loop shape was It was press-fitted until it reached mm, and the repulsive force from the test piece rounded into a loop was measured. It can be evaluated as a cured film excellent in low repulsion property, so that repulsive force is small.

[Evaluation method of solder heat resistance]

Each liquid photosensitive resin composition was applied onto an electrolytic copper foil having a thickness of 35 μm using a Baker-style applicator. At this time, the coating amount of the liquid photosensitive resin composition was adjusted so that the thickness of the cured film might be 20 μm. Next, after drying the coating film containing the liquid photosensitive resin composition under the conditions of a drying temperature of 80° C. and a drying time of 20 minutes, the entire surface of the coating film was irradiated with ultraviolet rays under the conditions of a cumulative exposure amount of 300 mJ/cm 2 and exposed. Subsequently, spray development was performed for 90 seconds under conditions of a discharge pressure of 1.0 kgf/mm 2 to the coated film after exposure using a 1.0% by weight aqueous solution of sodium carbonate (temperature: 30° C.) as a developing solution. Next, after washing the developed coating film with pure water, it was heated in an oven at a temperature of 150°C for 60 minutes to form a cured film of the liquid photosensitive resin composition on the electrolytic copper foil, and a test piece was obtained. After immersing the obtained test piece in a soldering bath at a temperature of 260°C, the operation of pulling up after 10 seconds was made one operation, and this operation was performed three times in succession. Next, the state of the surface of the cured film was visually observed, and the case where swelling or peeling was not observed on the surface of the cured film was evaluated as "A (excellent in solder heat resistance)". On the other hand, the case where swelling or peeling was confirmed on the surface of the cured film was evaluated as "B (not excellent in solder heat resistance)".

[Evaluation Method of Electrical Insulation Reliability]

First, a flexible copper foil (thickness: 12 μm) bonded to both sides of a polyimide film (“Pixio (registered trademark) BP FRS-142#SW” manufactured by Kaneka Corporation, thickness: 25 μm) as a film-shaped support body Laminates were prepared. The copper foil on one side of this flexible copper-clad laminate was patterned to form a comb-shaped pattern with line width/space width = 100 µm/100 µm on the film-shaped support. Subsequently, the laminated plate on which the comb pattern was formed was immersed in a 10% by volume sulfuric acid aqueous solution for 1 minute, and then washed with pure water. Next, each liquid photosensitive resin composition was applied onto the comb-shaped pattern using a Baker-style applicator. At this time, the coating amount of the liquid photosensitive resin composition was adjusted so that the thickness of the cured film on the comb pattern would be 20 μm. Next, after drying the coating film containing the liquid photosensitive resin composition under the conditions of a drying temperature of 80° C. and a drying time of 20 minutes, the entire surface of the coating film was irradiated with ultraviolet rays under the conditions of a cumulative exposure amount of 300 mJ/cm 2 and exposed. Subsequently, spray development was performed for 90 seconds under conditions of a discharge pressure of 1.0 kgf/mm 2 to the coated film after exposure, using a 1.0% by weight aqueous solution of sodium carbonate (temperature: 30° C.) as a developing solution. Next, after washing the developed coating film with pure water, it was heated in an oven at a temperature of 150°C for 60 minutes to form a cured film of the liquid photosensitive resin composition on the comb pattern, and a test piece was obtained. Next, in an environment of a temperature of 85°C and a relative humidity of 85%, a DC voltage of 100 V was applied to both terminal portions of the test piece, and a change in resistance between the terminals was observed. Then, when 1000 hours elapsed from the start of application, the case where a resistance value of 1.0×10 ⁸ Ω or more was exhibited was evaluated as “A (excellent electrical insulation reliability)”. On the other hand, a case where a resistance value of less than 1.0×10 ⁸ Ω was exhibited after 1000 hours elapsed from the start of application was evaluated as “B (not excellent in electrical insulation reliability)”.

[Method for Evaluating Adhesion on Surface of Coating Film]

Each liquid photosensitive resin composition was applied on a part (area of 100 mm x 100 mm area) of a polyimide film (“Apical (registered trademark) 25NPI” manufactured by Kaneka Corporation) having a thickness of 25 μm using a baker’s applicator. . At this time, the application quantity of the liquid photosensitive resin composition was adjusted so that the thickness of the coating film containing the liquid photosensitive resin composition after drying might be set to 20 micrometers. Next, the coating film was dried on conditions of a drying temperature of 80°C and a drying time of 20 minutes to obtain a film having a coating film. Next, the film having the coating film is cut into a strip shape of 50 mm × 30 mm, the coating film surfaces are overlapped with the coating film inside, and a weight of 300 g is placed on the overlapped portion for 3 seconds, the weight is removed, and the overlapping One part was removed. Then, the surface of the coated film after peeling was visually observed, and the case where no marks adhered to the coated film surface remained was evaluated as "A (good)", and the case where marks adhered to the coated film surface remained was evaluated as "B". (not good)”.

<Production of substrate>

First, a flexible copper-clad laminate was prepared in which electrolytic copper foil was bonded to both surfaces of a polyimide film (“Pixio (registered trademark) BP FRS#SW” manufactured by Kaneka Corporation) as a film-shaped support. In this flexible copper-clad laminate, 600 through holes each having diameters (opening diameters) of 30 μm, 50 μm, 80 μm, 100 μm, 130 μm, 190 μm, 240 μm and 290 μm were provided. Subsequently, cleaning treatment (desmear treatment) and carbon treatment were performed in the through hole. Next, after carrying out the electrolytic copper plating process on the inside of the through hole, wiring was formed by patterning the electrolytic copper foil on both sides to obtain a film support and a substrate having wiring provided on both sides of the film support and having through holes. . For each of Examples 1 to 25 and Comparative Examples 1 to 8, in Tables 1 to 7 described later, the vertical and horizontal widths of the substrates used, the thickness of the film-shaped supports used, and the thickness of wiring of the substrates used are shown.

<Application of liquid photosensitive resin composition to substrate and formation of coating>

On both sides of the substrate produced in the above procedure, a liquid photosensitive resin composition (one of the liquid photosensitive resin compositions described in Tables 1 to 7 described later) is applied using a vertical suspension roll coater equipped with a pair of coating rolls. applied At this time, the liquid photosensitive resin composition was simultaneously applied to both surfaces of the substrate. Application conditions were as follows. In addition, in the following application conditions, "application roll" means "each of a pair of application rolls."

· Material of the surface layer (surface layer roll) of the application roll: ethylene propylene rubber

· Width of surface layer roll: 680 mm

· Roll diameter of the application roll: as described in Tables 1 to 7 described later

· Type of groove of application roll: as described in Tables 1 to 7 described later

Pitch of the grooves of the application roll: 700 μm

· Opening width of the groove of the application roll: 700㎛

· Cross-sectional shape of the groove of the application roll: V-shape

· Depth of the groove of the application roll: 350㎛

Doctor bar pressure: 1.5kgf/cm2

· Press-in amount of application roll: 150㎛

Rotational speed of application roll: 5 m/min

Then, the substrate coated with the liquid photosensitive resin composition was dried under conditions of a drying temperature of 80°C and a drying time of 20 minutes in a suspended state. The thickness of the coating film containing the liquid photosensitive resin composition after drying (thickness of the coating film on the wiring) was 20 µm on both sides.

<Evaluation method of substrate>

[Landfillability]

After drying, the through holes of each substrate (specifically, 600 through holes each having diameters of 30 μm, 50 μm, 80 μm, 100 μm, 130 μm, 190 μm, 240 μm and 290 μm) were observed with an optical microscope, The maximum diameter of the through-holes when the filling rate was 100% (when all 600 through-holes were filled) was taken as the evaluation value of the embedding property. For example, "Evaluation value of embeddability is 50 µm" indicates that all 600 through-holes of 30 µm and 50 µm in diameter are filled, but 600 through-holes of 80 µm in diameter are filled. It means that part or all of is not charged. Therefore, it can be evaluated that the embedding property is excellent, so that this evaluation value is large.

[Attachment of Substrate to Applying Roll]

Under the conditions described in the above <Application of liquid photosensitive resin composition to substrate and formation of coating film>, when the liquid photosensitive resin composition is applied to the substrate by operating the vertical suspension roll coater continuously for 24 hours, the application roll of the substrate The presence or absence of concubine was visually confirmed. And the following criteria judged about sticking with the application|coating roll of a board|substrate.

(Criterion for sticking the substrate with the coating roll)

A: The sticking of the board|substrate to the roll was not confirmed until 24 hours after the start of operation.

B: Although sticking of the substrate to the roll was not confirmed until 3 minutes after the start of operation, sticking of the substrate to the roll was confirmed between 3 minutes and 24 hours later.

C: The sticking of the board|substrate to the roll was confirmed until 3 minutes after the start of operation.

[Appearance of coating]

The coating film of each board|substrate after drying was visually observed, and the presence or absence of pinholes, non-uniform coating of the coating film covering the wiring, traces of grooves of the coating roll, and stripes were respectively confirmed. Then, the appearance of the coating film was judged according to the following criteria. When the judgment was A or B, it was evaluated as "it is possible to suppress the appearance defect of the coating film." On the other hand, when the judgment was C, it was evaluated as "the occurrence of poor appearance of the coating film cannot be suppressed."

(Criterion for determining the appearance of the coating film)

A: No pinholes, coating unevenness, groove marks, or streaks were observed.

B: A total of one or two defective locations of at least one of pinholes, coating unevenness, groove marks, and streaks were confirmed.

C: A total of 3 or more defective locations of at least one of pinholes, coating unevenness, groove marks, and streaks were confirmed.

[Appearance of the substrate on which the coating film is formed]

The appearance of each board|substrate after drying was visually observed, and the presence/absence of tearing of a board|substrate and deformation of a board|substrate was confirmed, respectively. And the appearance of the board|substrate on which the coating film was formed was judged according to the following criteria. When the judgment was A or B, it was evaluated as "it is possible to suppress occurrence of defective appearance of the substrate on which the coating film is formed." On the other hand, when the judgment was C, it was evaluated as "the appearance defect of the board|substrate on which the coating film was formed cannot be suppressed."

(Criterion for determining the appearance of a substrate on which a coating film is formed)

A: Neither the tearing of the substrate nor the deformation of the substrate was confirmed.

B: No tearing of the substrate was observed, but deformation of the substrate was observed.

C: Both tearing of the substrate and deformation of the substrate were confirmed.

<Evaluation result>

For Examples 1 to 25 and Comparative Examples 1 to 8, the components of the liquid photosensitive resin composition used and their compounding amounts, the vertical and horizontal widths of the substrates used, the thickness of the film-shaped support used, the thickness of the wiring of the substrates used, the coating rolls used Tables 1 to 7 show the roll diameter, the type of groove of the application roll used, the physical properties and evaluation results of the liquid photosensitive resin composition used, and the evaluation results of the substrate. In Tables 1 to 7, the numerical value in the column of the composition of the liquid photosensitive resin composition is the compounding amount of the component (unit: parts by weight). In Tables 1 to 7, the amount of the organic solvent in Resin Solution SP1, Resin Solution SP2, Resin Solution SP3, or Resin Solution SP4 is included in the blending amount of component (E) (organic solvent). In Tables 1 to 7, "-" means that the component is not blended. In Tables 1 to 7, "ring-shaped grooves" are a plurality of independent ring-shaped grooves.

In Tables 1 to 7, "369", "828", "8070", "972", "1000", "TEGDM", "DEGDE", "321", and "2000" respectively represent the following same.

369: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 as an optical radical polymerization initiator ("Omnirad (registered trademark) 369" manufactured by IGM Resins)

828: Epoxy resin ("jER (registered trademark) 828" manufactured by Mitsubishi Chemical Corporation)

8070: Crosslinked polyurethane particles ("Dynamic Beads (registered trademark) UCN-8070CM Clear" manufactured by Dainichi Seika Kogyo Co., Ltd., average particle diameter: 7 μm)

972: Silica particles ("Aerosil (registered trademark) R-972" manufactured by Nippon Aerosil Co., Ltd., average particle diameter: 0.016 µm)

1000: Crosslinked polyurethane particles (“Art Pearl (registered trademark) C-1000T” manufactured by Negami Kogyo Co., Ltd., average particle diameter: 3 μm)

TEGDM: Triethylene glycol dimethyl ether (a water-soluble organic solvent with a boiling point of 216 ° C)

DEGDE: diethylene glycol diethyl ether (a water-soluble organic solvent with a boiling point of 189 ° C)

321: EO modified bisphenol A dimethacrylate ("Pancryl (registered trademark) FA-321M" manufactured by Showa Denko Materials, average added mole number of EO: 10)

2000: Butadiene-based antifoaming agent (“Floren AC-2000” manufactured by Kyoeisha Chemical Co., Ltd.)

In Examples 1 to 25, each of the pair of application rolls used had a plurality of ring-shaped grooves. In Examples 1 to 25, the plurality of ring-shaped grooves were independent of each other. In Examples 1 to 25, the roll diameter of the coating roll used when applying the liquid photosensitive resin composition using a vertical suspension roll coater was 70 mm or more and 150 mm or less. In Examples 1 to 25, the viscosities of the liquid photosensitive resin composition used were 1.0 Pa·s or more and 15.0 Pa·s or less. In Examples 1 to 25, the TI values of the liquid photosensitive resin composition used were 1.5 or more and 3.0 or less. In Examples 1-25, the elastic modulus of the cured film of the used liquid photosensitive resin composition was 0.1 GPa or more and 1.5 GPa or less.

In Examples 1 to 25, the evaluation of the appearance of the coating film was A or B. Therefore, the production methods of Examples 1 to 25 were able to suppress the appearance defects of the coating film. In Examples 1 to 25, the evaluation of the appearance of the substrate on which the coating film was formed was A or B. Therefore, the manufacturing methods of Examples 1 to 25 were able to suppress the appearance defect of the substrate on which the coating film was formed.

In Comparative Example 1, the viscosity of the liquid photosensitive resin composition used was exceeding 15.0 Pa·s. In Comparative Example 1, the TI value of the liquid photosensitive resin composition used was exceeding 3.0. In Comparative Example 2, the elastic modulus of the cured film of the liquid photosensitive resin composition used was exceeding 1.5 GPa. In Comparative Example 3, the viscosity of the liquid photosensitive resin composition used was exceeding 15.0 Pa·s. In Comparative Example 4, the TI value of the liquid photosensitive resin composition used was exceeding 3.0. In Comparative Example 5, the TI value of the liquid photosensitive resin composition used was less than 1.5. In Comparative Example 6, the roll diameter of the coating roll used when applying the liquid photosensitive resin composition using a vertical suspension roll coater exceeded 150 mm. In Comparative Example 7, the roll diameter of the coating roll used when applying the liquid photosensitive resin composition using a vertical suspension roll coater was less than 70 mm. In Comparative Example 8, the groove of the coating roll used when applying the liquid photosensitive resin composition using a vertical suspension roll coater was a spiral groove.

In Comparative Examples 1, 3 to 5 and 7, the evaluation of the external appearance of the coating film was C. Therefore, the manufacturing methods of Comparative Examples 1, 3 to 5, and 7 could not suppress the appearance defect of the coating film. In Comparative Examples 2, 6, and 8, the evaluation of the appearance of the substrate on which the coating film was formed was C. Therefore, the manufacturing methods of Comparative Examples 2, 6, and 8 could not suppress the appearance defect of the board|substrate on which the coating film was formed.

From the above results, according to the present invention, it was found that a method for manufacturing a flexible printed circuit board capable of suppressing the appearance defects of a coating film and appearance defects of a substrate formed with a coating film can be provided.

11: Substrate
12a, 12b, 100: application roll
13: film-shaped support
14: Wiring
15: hole
17: liquid photosensitive resin composition
120a: ring-shaped groove

Claims (12)

A method for producing a flexible printed circuit board in which a liquid photosensitive resin composition is applied to both surfaces of a film-like support and a substrate having wiring provided on both sides of the film-like support using a vertical suspension roll coater,
A hole is provided in the board,
The vertical suspension roll coater includes a pair of coating rolls each having a plurality of independent ring-shaped grooves,
The roll diameter of the coating roll is 70 mm or more and 150 mm or less,
The liquid photosensitive resin composition has a viscosity of 1.0 Pa·s or more and 15.0 Pa·s or less after being rotated at a rotation speed of 50 rpm for 3 minutes, and is rotated for 3 minutes at a rotation speed of 5 rpm for a viscosity after being rotated for 3 minutes at a rotation speed of 50 rpm. The ratio of the viscosity after being made is 1.5 or more and 3.0 or less,
The elastic modulus of the cured film of the liquid photosensitive resin composition is 0.1 GPa or more and 1.5 GPa or less,
When the liquid photosensitive resin composition is applied, the liquid photosensitive resin composition is simultaneously applied to both surfaces of the substrate. The method for manufacturing a flexible printed circuit board according to claim 1, wherein both the horizontal and vertical widths of the film-shaped support are 200 mm or more and 600 mm or less. The method for manufacturing a flexible printed circuit board according to claim 1 or 2, wherein the thickness of the film-shaped support is 8.0 μm or more and 50.0 μm or less. The method for manufacturing a flexible printed circuit board according to any one of claims 1 to 3, wherein the wiring has a thickness of 8 μm or more and 50 μm or less. The method for manufacturing a flexible printed circuit board according to any one of claims 1 to 4, wherein the hole has a diameter of 50 μm or more and 250 μm or less. The method according to any one of claims 1 to 5, wherein the film-shaped support is made of polyimide, polyamide, polyester, polycarbonate, polyarylate, polytetrafluoroethylene, and polychlorotrifluoroethylene. , polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesins, tetrafluoroethylene/hexafluoropropylene copolymers, ethylene/tetrafluoroethylene copolymers, and ethylene/chlorotrifluoroethylene copolymers. A method for manufacturing a flexible printed circuit board comprising at least one type of polymer. The flexible print according to any one of claims 1 to 6, wherein the liquid photosensitive resin composition has a ratio of viscosity after rotation at 50 rpm for 3 minutes to viscosity after rotation at 50 rpm for 24 hours of 1.20 or less. A method for manufacturing a substrate. The flexible photosensitive resin composition according to any one of claims 1 to 7, wherein the liquid photosensitive resin composition contains a binder polymer, a radical photopolymerization initiator, a thermosetting resin, particles having an average particle diameter of 0.01 μm or more and 100 μm or less, and an organic solvent. A method for manufacturing a printed circuit board. The method of claim 8, wherein the binder polymer is a polymer having a urethane bond in one molecule, a polymer having an imide group in one molecule, a polymer having a (meth)acryloyl group in one molecule, and a polymer having a carboxyl group in one molecule. A method for producing a flexible printed circuit board, which is at least one kind of polymer selected from the group consisting of: The method for manufacturing a flexible printed circuit board according to claim 8 or 9, wherein the organic solvent is a water-soluble organic solvent having a boiling point of 180°C or higher. The method for producing a flexible printed circuit board according to any one of claims 8 to 10, wherein the content of the particles is 5 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the binder polymer. The method for manufacturing a flexible printed circuit board according to any one of claims 8 to 11, wherein the particles are crosslinked polymer particles.

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