CN117063124A - Method for manufacturing flexible printed board - Google Patents

Method for manufacturing flexible printed board Download PDF

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Publication number
CN117063124A
CN117063124A CN202280022002.3A CN202280022002A CN117063124A CN 117063124 A CN117063124 A CN 117063124A CN 202280022002 A CN202280022002 A CN 202280022002A CN 117063124 A CN117063124 A CN 117063124A
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CN
China
Prior art keywords
substrate
resin composition
photosensitive resin
film
flexible printed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202280022002.3A
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Chinese (zh)
Inventor
关藤由英
堀江庆太
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kaneka Corp
Original Assignee
Kaneka Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kaneka Corp filed Critical Kaneka Corp
Publication of CN117063124A publication Critical patent/CN117063124A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/28—Processes for applying liquids or other fluent materials performed by transfer from the surfaces of elements carrying the liquid or other fluent material, e.g. brushes, pads, rollers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
    • B05D3/061—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using U.V.
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/24—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/027—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/027—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds
    • G03F7/032—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds with binders
    • G03F7/035—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds with binders the binders being polyurethanes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/027—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds
    • G03F7/032—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds with binders
    • G03F7/037—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds with binders the binders being polyamides or polyimides
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/16—Coating processes; Apparatus therefor
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Plasma & Fusion (AREA)
  • Non-Metallic Protective Coatings For Printed Circuits (AREA)

Abstract

A method for manufacturing a flexible printed board comprises a step of applying a liquid photosensitive resin composition (17) to both sides of a substrate (11) using a vertical lift roll coater, wherein the substrate (11) has a film-like support (13) and wirings (14) provided on both sides of the film-like support (13). A hole (15) is provided in the substrate (11). The liquid photosensitive resin composition (17) contains a binder polymer, a photo radical polymerization initiator, a multifunctional epoxy compound, an epoxy curing accelerator, and a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule. When the liquid photosensitive resin composition (17) is applied, the liquid photosensitive resin composition (17) is applied simultaneously to both surfaces of the substrate (11).

Description

Method for manufacturing flexible printed board
Technical Field
The present invention relates to a method for manufacturing a flexible printed board.
Background
With miniaturization, weight reduction, and multi-functionalization of electronic components, there is a demand for a fine feature (hereinafter, sometimes referred to as "fine opening feature") that allows components to be mounted on lands or the like having a smaller diameter in an opening of a flexible printed board incorporated into an electronic device. As a method of forming the fine openings of the flexible printed circuit board, a method of forming a film formed of a liquid photosensitive resin composition on a component mounting portion of the flexible printed circuit board (hereinafter, may be simply referred to as a "substrate") before forming a protective film, and patterning the film by photolithography to form a protective film provided with the fine openings is known.
In addition, with recent increases in the screen size and thickness of portable devices such as smartphones, a flexible printed circuit board used in a portable device is required to have low resilience, which is easy to maintain a curved shape, in order to be easily folded and assembled in a narrow portion. As a method for improving the low resilience of a flexible printed board, a method of partially coating a thermosetting resin composition called a flex ink on a flex portion of the board is known.
In addition, through holes (via holes) and non-through holes (blind holes) are usually formed in a flexible printed board, and when the liquid photosensitive resin composition is applied to the board, it is necessary to embed the liquid photosensitive resin composition in the through holes or the non-through holes. Therefore, it is also required for the flexible printed board that the liquid photosensitive resin composition is sufficiently embedded in the through-holes or the non-through-holes (hereinafter, referred to as "embeddability"). Hereinafter, the through hole and the non-through Kong Huizong may be referred to as "holes". In the following, the hole means 1 hole or a plurality of holes. The substrate provided with the hole includes a substrate provided with only the through hole, a substrate provided with only the non-through hole, and a substrate provided with both the through hole and the non-through hole.
In view of such a situation, various protective film resin compositions (specifically, liquid photosensitive resin compositions and the like) and devices for applying the protective film resin compositions have been studied in order to improve the fine openability, low rebound resilience and embeddability of a flexible printed board (for example, refer to patent documents 1 to 4).
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2015-161764
Patent document 2: japanese patent laid-open No. 2020-148971
Patent document 3: international publication No. 2018/092330
Patent document 4: japanese patent application laid-open No. 2015-115602
Disclosure of Invention
Problems to be solved by the invention
However, when the techniques described in patent documents 1 to 4 are used alone, it is difficult to suppress the immersion of the plating solution between the protective film (cured film) and the substrate in the plating process (for example, gold plating process) and suppress the discoloration of the wiring in the heating process (for example, hot pressing process). The impregnation of the plating solution in the plating step and discoloration of the wiring in the heating step result in a decrease in the yield of the product. Hereinafter, the characteristic that can suppress impregnation of the plating solution in the plating step is sometimes referred to as "plating solution resistance". Further, the characteristic that can suppress discoloration of the wiring in the heating step is sometimes described as "discoloration resistance of the wiring".
The present invention has been made in view of these problems, and an object thereof is to provide a method for producing a flexible printed board excellent in plating solution resistance and discoloration resistance of wiring.
Solution for solving the problem
The method for manufacturing a flexible printed board comprises a step of applying a liquid photosensitive resin composition to both surfaces of a substrate having a film-like support and wiring lines provided on both surfaces of the film-like support by using a vertical lift roll coater. Holes are provided in the substrate. The liquid photosensitive resin composition contains a binder polymer, a photo radical polymerization initiator, a multifunctional epoxy compound, an epoxy curing accelerator, and a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule. When the liquid photosensitive resin composition is applied, the liquid photosensitive resin composition is applied simultaneously to both surfaces of the substrate.
In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the film-like support has a lateral width and a longitudinal width of 200mm to 600 mm.
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 method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the thickness of the wiring is 8 μm or more and 50 μm or less.
In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the hole has a diameter of 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-like support contains one or more polymers selected from the group consisting of polyimide, polyamide, polyester, polycarbonate, polyarylate, polytetrafluoroethylene, polytrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, and ethylene-chlorotrifluoroethylene copolymer.
In the method for producing a flexible printed circuit board according to an embodiment of the present invention, the binder polymer is at least one polymer selected from the group consisting of a polymer having a urethane bond in 1 molecule, a polymer having an imide group in 1 molecule, a polymer having a (meth) acryloyl group in 1 molecule, and a polymer having a carboxyl group in 1 molecule.
In the method for manufacturing a flexible printed circuit board according to an embodiment of the present invention, the content of the epoxy curing accelerator is 0.1 parts by weight or more and 0.5 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 acid value of the binder polymer is 10mgKOH/g or more.
In the method for manufacturing a flexible printed circuit board according to one embodiment of the present invention, the vertical lift roll coater includes a pair of coating rolls, and the roll diameter of the coating rolls is 70mm or more and 150mm or less.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a method for manufacturing a flexible printed board excellent in plating solution resistance and discoloration resistance of wiring can be provided.
Drawings
Fig. 1 is a main part sectional view for explaining an example of a method for manufacturing a flexible printed board according to the present invention.
Fig. 2 is a cross-sectional view of another main part for explaining an example of a method for manufacturing a flexible printed board according to the present invention.
Fig. 3 is a cross-sectional view of another main part for explaining an example of a method for manufacturing a flexible printed board according to the present invention.
Fig. 4 is a cross-sectional view of another main part for explaining an example of a method for manufacturing a flexible printed board according to the present invention.
Fig. 5 is a cross-sectional view of another main part for explaining an example of a method for manufacturing a flexible printed board according to the present invention.
Fig. 6 is a cross-sectional view of an application roller used in an example of a method for producing a flexible printed board according to the present invention when the application roller is cut in a plane including the axis thereof.
Detailed Description
The preferred embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. The academic literature and patent literature described in the present specification are incorporated by reference in their entirety into the present specification.
First, terms used in the present specification will be described. "roll coater" refers to a coating apparatus having a pair of rotatable coating rolls. The coating method of the roll coater includes a vertical lift type in which the liquid photosensitive resin composition is coated on the substrate while the substrate is lifted up in the vertical direction, and a horizontal transfer type in which the liquid photosensitive resin composition is coated on the substrate while the substrate is transferred in the horizontal direction. Compared with a horizontal conveying type roller coater, the vertical lifting type roller coater can realize simplification of a coating device and space saving. In addition, since the vertical lift roll coater can dry the substrate coated with the liquid photosensitive resin composition in a suspended state, adhesion of foreign matter in the drying step of a coating film (hereinafter, sometimes simply referred to as "coating film") formed from the liquid photosensitive resin composition can be suppressed.
The term "photo radical polymerization initiator" refers to a compound that generates radicals as active species by light irradiation. "epoxy compound" refers to a compound having 1 or more epoxy groups in 1 molecule. "multifunctional epoxy compound" refers to an epoxy compound having 2 or more epoxy groups in 1 molecule. "epoxy curing accelerator" refers to a compound that promotes the crosslinking/chain extension reaction of an epoxy compound.
The "thickness" of the film-like support is an arithmetic average of 10 measured values obtained by randomly selecting 10 measured 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 measured points. The "thickness" of the wiring is an arithmetic average of 10 measured values obtained by randomly selecting 10 measured positions from an electron microscope image of a cross section of the wiring cut in the thickness direction and measuring the thickness of the selected 10 measured positions.
The "average particle diameter" is a volume-based median particle diameter (particle diameter of 50% of the cumulative distribution value) measured by a laser diffraction/scattering particle size distribution measuring apparatus (for example, "LA-950V2" manufactured by horiba ltd.).
Hereinafter, the compound name may be followed by "series" to collectively refer to the compound and its derivative. In the case where the compound name is followed by a "system" to indicate a polymer name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof. In addition, acrylic acid and methacrylic acid are sometimes collectively referred to as "(meth) acrylic acid". In addition, the acrylate and the methacrylate are sometimes collectively referred to as "(meth) acrylate". In addition, the acryl and methacryl groups are sometimes collectively referred to as "(meth) acryl groups". The components, functional groups, and the like exemplified in the present specification may be used singly or in combination of 2 or more unless otherwise specified.
In the drawings referred to in the following description, each component is schematically shown on the main body for easy understanding, and the size, number, shape, etc. of each component shown may be different from the actual ones for convenience in making the drawings. In the drawings described below, the same reference numerals are given to the same components as those in the drawings described above, and the description thereof may be omitted for convenience of description.
Method for producing flexible printed circuit board
The method for manufacturing a flexible printed board according to the present embodiment includes a step of applying a liquid photosensitive resin composition to both surfaces of a substrate having a film-like support and wirings provided on both surfaces of the film-like support using a vertical lift roll coater. Holes are provided in the substrate. The liquid photosensitive resin composition contains a binder polymer, a photo radical polymerization initiator, a multifunctional epoxy compound, an epoxy curing accelerator, and a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule. When the liquid photosensitive resin composition is applied, the liquid photosensitive resin composition is applied simultaneously to both sides of the substrate.
In the method for manufacturing a flexible printed board according to the present embodiment, since the liquid photosensitive resin composition is applied to both surfaces of the board at the same time, the liquid photosensitive resin composition can be embedded in the holes provided in the board and applied at the same time.
According to the present embodiment, a method for manufacturing a flexible printed board excellent in plating solution resistance and discoloration resistance of wiring can be provided. The reason is presumed as follows.
Since the liquid photosensitive resin composition used in the present embodiment contains a polyfunctional epoxy compound, an epoxy curing accelerator, and a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule, there is a tendency that the crosslinking density of a cured film (hereinafter, may be simply referred to as "cured film of the liquid photosensitive resin composition" or "cured film") formed by curing a coating film formed from the liquid photosensitive resin composition increases. Therefore, according to the present embodiment, it is possible to suppress infiltration of the plating solution between the cured film and the substrate in the plating step, and to suppress permeation of oxygen through the cured film, which causes discoloration of the wiring, in the heating step. In addition, in the present embodiment, by simultaneously applying the liquid photosensitive resin composition on both surfaces of the substrate, the roll pressure can be uniformly conducted on the substrate, and thus a cured film having a uniform thickness can be easily obtained. Thus, according to the present embodiment, a flexible printed board excellent in plating solution resistance and discoloration resistance of the wiring can be manufactured.
In this embodiment, in order to obtain a flexible printed board excellent in flexibility, plating solution resistance, and discoloration resistance of wiring, it is preferable that the liquid photosensitive resin composition contains a radical polymerizable compound having 1 radical polymerizable group in a range of 3 to 6 in a molecule.
In this embodiment, in order to suppress occurrence of appearance defects (specifically, deformation of the substrate, breakage of the substrate, and the like) of the substrate on which the coating film is formed, the lateral width and the longitudinal width of the film-like support are preferably 150mm to 650mm, more preferably 200mm to 600mm, still more preferably 250mm to 550 mm. The term "lateral width of the film support" refers to the width of the film support in a direction parallel to the axial direction of the coating roller when the liquid photosensitive resin composition is coated on the substrate. The term "longitudinal width of the film-like support" refers to the width of the film-like support in a direction perpendicular to the axial direction of the coating roller when the liquid photosensitive resin composition is coated on the substrate.
In this embodiment, in order to suppress occurrence of defective appearance of the substrate on which the coating film is formed, the thickness of the film-like support is preferably 8.0 μm or more, more preferably 10.0 μm or more, and still more preferably 12.0 μm or more. In the present embodiment, in order to suppress occurrence of appearance defects (specifically pinholes, uneven coverage of the coating film covering the wiring, marks of grooves of the coating roller, and streaks) of the coating film, the thickness of the film-like support is preferably 50.0 μm or less.
In this embodiment, in order to suppress occurrence of appearance defects in 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, still more preferably 15 μm or more and 50 μm or less.
In this embodiment, in order to obtain a flexible printed board which ensures conduction between wirings provided on both sides of a film-like support and is excellent in embeddability, a diameter (opening diameter) of a hole provided in the board is preferably 50 μm or more and 250 μm or less, more preferably 50 μm or more and 200 μm or less.
In the present embodiment, in order to obtain a flexible printed board which ensures flexibility of the obtained cured film, can suppress occurrence of appearance defects of the coating film and appearance defects of the substrate on which the coating film is formed, and is excellent in plating solution resistance and discoloration resistance of the wiring, the following condition 1 is preferably satisfied, the following condition 2 is more preferably satisfied, and the following condition 3 is more preferably satisfied.
Condition 1: the liquid photosensitive resin composition contains a radical polymerizable compound having 1 radical polymerizable group in the range of 3 to 6 in the molecule, and the width of the film-shaped support in the transverse direction and the width in the longitudinal direction are both 200mm to 600 mm.
Condition 2: the film-like support has a thickness of 8.0 μm or more and 50.0 μm or less, which satisfies the above condition 1.
Condition 3: the thickness of the wiring is 8 μm or more and 50 μm or less while satisfying the above condition 2.
The present embodiment will be described below with reference to the drawings. Fig. 1 to 5 are main part sectional views for explaining an example (particularly, a coating process) of a method for manufacturing a flexible printed board according to the present embodiment. In fig. 1 to 5, the left side of the drawing is set as the upstream side of the manufacturing process, and the right side of the drawing is set as the downstream side of the manufacturing process.
In the coating process of the present embodiment, the substrate 11 suspended by the suspension jig 10 is first transferred from the upstream side of the manufacturing process to the upper side of the pair of coating rolls 12a and 12b (fig. 1). In fig. 1, the coating roll 12a is a coating roll located on the upstream side of the manufacturing process, and the coating roll 12b is a coating roll located on the downstream side of the manufacturing process. The coating roller 12a and the coating roller 12b preferably have a roller diameter of 70mm or more and 150mm or less.
The substrate 11 includes a film-like support 13 and wirings 14 provided on both sides of the film-like 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 pitch (pitch) of the wirings 14 is, for example, 10 μm or more and 200 μm or less.
In the state of fig. 1, a gap to the extent that the substrate 11 can pass is provided between the coating roller 12a and the coating roller 12 b. The applicator roll 12a is contacted with a blade 16a on the upstream side of the production process, and a predetermined pressure (for example, 0.5 kgf/cm) is applied by the blade 16a 2 Above and 3.0kgf/cm 2 The following are described below). The applicator roll 12b is contacted with a blade 16b on the downstream side of the production process, and a predetermined pressure (for example, 0.5 kgf/cm) is applied by the blade 16b 2 Above and 3.0kgf/cm 2 The following are described below).
The application roller 12a and the application roller 12b are rotated at predetermined rotational speeds (for example, 1 m/min or more and 10 m/min or less). A liquid photosensitive resin composition 17 is stored between the application roller 12a and the blade 16a, and between the application roller 12b and the blade 16 b. The liquid photosensitive resin composition 17 is transferred to the surface of the coating roller 12a and the surface of the coating roller 12 b.
The suspension jig 10 is lowered from the state shown in fig. 1, and the suspended substrate 11 is transferred between the coating rolls 12a and 12b to a position where the upper end portion of the substrate 11 is located between the coating rolls 12a and 12b (see fig. 2). Next, as shown in fig. 2, the suspension jig 10 releases the substrate 11 and the fixing jig 18 grips the lower end portion of the substrate 11.
Next, the respective rotating coating rollers 12a and 12b are inserted into the substrate 11 so as to sandwich the substrate 11 and apply pressure to the substrate 11, and the fixing jig 18 releases the lower end portion of the substrate 11 (fig. 3). When the substrate 11 is released by the fixing jig 18, the coating rollers 12a and 12b rotate, and the liquid photosensitive resin composition 17 is simultaneously coated on both surfaces of the substrate 11, and the substrate 11 is lifted upward. In the state of fig. 3, the amount of the coating roller 12a and the coating roller 12b to be inserted is, for example, in the range of 100 μm to 200 μm.
Next, the upper end portion of the substrate 11 lifted upward while the liquid photosensitive resin composition 17 is simultaneously applied to both surfaces is gripped by the suspension jig 10 (fig. 4). When the substrate 11 is lifted, the liquid photosensitive resin composition 17 is buried in the holes 15 provided in the substrate 11, and the coating film 19 formed of the liquid photosensitive resin composition 17 is formed on both surfaces of the substrate 11. In order to obtain a flexible printed board having more excellent plating solution resistance and discoloration resistance of the wiring, it is preferable to adjust the composition and coating conditions of the liquid photosensitive resin composition 17 so that the thickness of the periphery of the hole 15 in the film (cured film) formed by curing the coating film 19 is 10 μm or more. In addition, the upper end portion of the substrate 11 is gripped by the suspension jig 10 in a state where the suspension jig 10 is as close to the coating roller 12a and the coating roller 12b as possible, whereby the substrate 11 can be prevented from winding around the coating roller 12a or the coating roller 12 b.
Next, the substrate 11 having the coating film 19 formed on both surfaces thereof is transferred to the downstream side of the manufacturing process while being suspended by the suspension jig 10 (fig. 5). Next, 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 while being suspended. Next, the substrate 11 is dried while the substrate 11 passes through the inside of the drying furnace.
In the drying furnace, hot air from which environmental foreign matters are removed by a filter is blown, for example, to the coating film 19 formed on the substrate 11. Since the substrate 11 is in the form of a film, when a plurality of substrates 11 are dried at the same time, if the interval between the substrates 11 is narrow, the substrates 11 are blown by the circulation of hot air in the drying furnace, and the substrates 11 are easily stuck to each other. In the case where a plurality of substrates 11 are dried at the same time, it is preferable that the distance between the substrates 11 is larger than the longitudinal width of the substrates 11.
The drying temperature of the substrate 11 is preferably 60 ℃ or more and 130 ℃ or less, more preferably 70 ℃ or more and 120 ℃ or less. By setting the drying temperature of the substrate 11 to 60 ℃ or higher, the organic solvent contained in the liquid photosensitive resin composition 17 can be sufficiently removed, and therefore, adhesion of foreign matters to the dried coating film 19 and the like can be suppressed. In addition, by setting the drying temperature of the substrate 11 to 130 ℃ or lower, the curing reaction of the liquid photosensitive resin composition 17 can be suppressed, and therefore, in the photolithography step in the subsequent step, an increase in development time or the like can be suppressed. The drying temperature may be appropriately set by the number of substrates 11 charged into the drying oven and the coating speed.
The drying time of the substrate 11 is preferably 1 minute or more and 60 minutes or less, more preferably 3 minutes or more and 40 minutes or less. By setting the drying time to 1 minute or longer, the organic solvent contained in the liquid photosensitive resin composition 17 can be sufficiently removed, and thus adhesion of foreign matters to the dried coating film 19 and the like can be suppressed. Further, by setting the drying time to 60 minutes or less, the curing reaction of the liquid photosensitive resin composition 17 can be suppressed, and therefore, in the photolithography step in the subsequent step, an increase in development time or the like can be suppressed. The drying time may be appropriately set by the number of substrates 11 charged into the drying oven and the coating speed.
Next, an example of the application roller 12a and the application roller 12b will be described. Fig. 6 is a cross-sectional view of the coating roller 100, which is an example of the coating roller 12a and the coating roller 12b, when the coating roller is cut in a plane including the axial center thereof. The applicator roll 100 shown in fig. 6 includes a metal core 110 having a cylindrical hollow portion, and a surface layer roll 120 disposed on the outer peripheral surface of the core 110.
The top layer roller 120 is a roller to 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 ℃. The rubber constituting the top layer roller 120 is not particularly limited, but is preferably a rubber having chemical resistance and abrasion resistance such as butyl rubber, ethylene propylene rubber, urethane rubber, nitrile rubber, or the like.
The top layer roller 120 has a plurality of annular grooves 120a. The plurality of annular grooves 120a are independent of each other. The cross-sectional shape of the annular groove 120a is not particularly limited, and may be a V-shape, a U-shape, or the like. 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 annular groove 120a preferably has a V-shaped cross-section. The pitch P of the annular grooves 120a is, for example, 500 μm or more and 1000 μm or less. The opening width of the annular groove 120a is, for example, 500 μm or more and 1000 μm or less. The depth of the annular groove 120a is, for example, 200 μm or more and 900 μm or less. The coating roller 100 shown in fig. 6 has a plurality of independent annular grooves 120a, but the coating roller usable in the present invention is not limited thereto, and a coating roller provided with 1 spiral groove may be used. Among them, in order to suppress deformation of the substrate 11 by uniformly rolling the substrate 11 by conduction roller, it is preferable that each of the pair of coating rollers is a coating roller having a plurality of annular grooves each independently.
The width W of the top layer roller 120 may be appropriately selected according to the manner of the suspension board 11 (see fig. 1). For example, as shown in fig. 1, when the hanging jig 10 is used to hold only the upper end portion of the substrate 11, the application area of the liquid photosensitive resin composition 17 to the substrate 11 can be enlarged when the width W of the surface layer roller 120 is made larger than the lateral width of the substrate 11. On the other hand, when the left and right end portions of the substrate 11 are gripped by the suspension jigs (not shown), the gripping ends of the substrate 11 can be easily provided when the width W of the surface layer roller 120 is smaller than the lateral width of the substrate 11.
The roll diameter D of the coating roll 100 is preferably 70mm to 150mm, more preferably 80mm to 140mm, still more preferably 90mm to 130mm, particularly preferably 100mm to 120 mm. When the roll diameter D is 70mm or more, there is a tendency that the phenomenon (liquid accumulation) of the excessive liquid photosensitive resin composition 17 remaining between the coating roll 100 and the substrate 11 is less likely to occur. Accordingly, when the roller diameter D is 70mm or more, the coating film 19 tends to be inhibited from being marked with grooves or streaks of the coating roller 100. Further, by setting the roller diameter D to 150mm or less, breakage (specifically, breakage or the like) of the substrate 11 due to the pressure of the application roller 100 can be suppressed when the liquid photosensitive resin composition 17 is applied to the substrate 11.
Next, elements of the method for manufacturing a flexible printed circuit board according to the present embodiment will be described in detail.
[ film-like support ]
The film-shaped support is not particularly limited, but is preferably a film-shaped support containing one or more polymers selected from the group consisting of polyimide, polyamide, polyester, polycarbonate, polyarylate, polytetrafluoroethylene, polytrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, and ethylene-chlorotrifluoroethylene copolymer, more preferably a film-shaped support containing polyimide, from the viewpoints of heat resistance, chemical resistance, and dimensional stability. The film-shaped support may contain an additive such as a filler as a component other than the polymer. In order to form a film-like support excellent in flexibility, the content of the polymer in the film-like support is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and may be 100% by weight, based on the total amount of the film-like support.
[ Wiring ]
The wiring provided on the film-like support is not particularly limited, and from the viewpoints of wiring shape stability and wiring miniaturization, a wiring formed by etching an electrolytic copper foil or a rolled copper foil by a subtractive method or a wiring formed by screen-printing a copper paste or a silver paste on the film-like support is preferable.
[ hole ]
The holes provided in the substrate are not particularly limited, and those obtained by forming holes in a flexible copper-clad laminate sheet having a film-like support by using a laser processing machine (more specifically, a processing machine using a carbon dioxide laser, a UV laser, a YAG laser, an excimer laser, or the like), an NC drilling machine, or the like, subjecting the holes to a cleaning treatment (desmutting treatment) and a carbon treatment, and then subjecting the holes to a copper plating treatment (electroless copper plating treatment, electrolytic copper plating treatment, or the like) are preferable from the viewpoints of hole shape stability and interlayer connection reliability.
[ liquid photosensitive resin composition ]
The liquid photosensitive resin composition contains a binder polymer (hereinafter, sometimes referred to as "component (a)"), a photo radical polymerization initiator (hereinafter, sometimes referred to as "component (B)"), a multifunctional epoxy compound (hereinafter, sometimes referred to as "component (C)"), an epoxy curing accelerator (hereinafter, sometimes referred to as "component (D)"), and a radical polymerizable compound (hereinafter, sometimes referred to as "component (E)") having 3 or more radical polymerizable groups in 1 molecule. The liquid photosensitive resin composition may contain, as optional components, particles having an average particle diameter of 0.01 μm or more and 100 μm or less (hereinafter, sometimes referred to as "component (F)") and an organic solvent (hereinafter, sometimes referred to as "component (G)"). The liquid photosensitive resin composition may contain other components described later.
Component { (A) }
As the component (a), for example, a polymer which is soluble in the component (G) and has a weight average molecular weight of 1000 to 1000000 in terms of polyethylene glycol can be used. The method for measuring the weight average molecular weight in terms of polyethylene glycol is the same method as the example described later or a method based on the same. The term "component (A) is soluble in component (G)" means a solution obtained by adding 5 parts by weight of component (A) to 100 parts by weight of component (G), stirring at 40℃for 1 hour, cooling to 25℃and standing for 24 hours, and is a solution free from insoluble matter and precipitate.
By setting the weight average molecular weight of the component (a) to 1000 or more, the flexibility and chemical resistance of the resulting cured film can be improved. Further, by setting the weight average molecular weight of the component (a) to 1000000 or less, an excessive increase in viscosity of the liquid photosensitive resin composition can be suppressed.
Specific examples of the component (a) include polyurethane-based resins, (meth) acrylic resins, polyethylene-based resins, polystyrene-based resins, polyethylene-based resins, polypropylene-based resins, polyimide-based resins, polyamide-based resins, 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, which may be used alone or in combination of 2 or more.
Among them, it is preferable to use one or more polymers selected from the group consisting of a polymer having a urethane bond in 1 molecule, a polymer having an imide group in 1 molecule, a polymer having a (meth) acryloyl group in 1 molecule, and a polymer having a carboxyl group in 1 molecule as the component (a).
When a polymer having a urethane bond in 1 molecule is used as the component (a), the low resilience and fracture resistance of the resulting cured film are improved, and the warpage of the cured film tends to be reduced. In addition, when a polymer having an imide group in 1 molecule is used as the component (a), the heat resistance, flame retardancy and electrical insulation reliability of the obtained cured film tend to be improved. In addition, when a polymer having a (meth) acryloyl group in 1 molecule is used as the component (a), there is a tendency that photosensitivity of the liquid photosensitive resin composition is improved and chemical resistance of the obtained cured film is improved. In addition, when a polymer having a carboxyl group in 1 molecule is used as the component (a), alkali developability of the liquid photosensitive resin composition is improved, and adhesion between the obtained cured film and the substrate tends to be improved.
The component (a) may be a polymer having a plurality of functional groups in 1 molecule. For example, when a polymer having a urethane bond and an imide group in 1 molecule is used as the component (a), the resulting cured film tends to be improved in low resilience, fracture resistance, heat resistance, flame retardancy, and electrical insulation reliability, and the warp of the cured film tends to be reduced. In addition, when a polymer having a urethane bond, a carboxyl group, and a (meth) acryloyl group in 1 molecule is used as the component (a), photosensitivity and alkali developability of the liquid photosensitive resin composition, low resilience, breakage resistance, and chemical resistance of the obtained cured film, and adhesiveness of the obtained cured film to a substrate tend to be improved, and warpage of the cured film tends to be reduced. Thus, the polymer having a urethane bond in 1 molecule preferably further has one or more functional groups selected from the group consisting of an imide group, a carboxyl group and a (meth) acryl group.
(1 Polymer having urethane bond in molecule)
"Polymer having urethane bonds in 1 molecule" refers to a polymer having at least 1 urethane bond in 1 molecule. Examples of the polymer having a urethane bond in the molecule 1 include a polymer having a repeating unit 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).
In the general formula (1), the general formula (2) and the general formula (3), R 1 And X 1 Each independently represents a 2-valent organic group.
Examples of the diol compound represented by the general formula (1) include alkylene diols such as ethylene glycol, diethylene glycol, propylene glycol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 2-methyl-1, 8-octanediol, 1, 9-nonanediol, 1, 10-decanediol, 1, 4-cyclohexanediol, and 1, 4-cyclohexanedimethanol; polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, random copolymers of tetramethylene glycol and neopentyl glycol; polyester diol obtained by reacting a polyhydric alcohol with a polybasic acid; a polycarbonate diol having a carbonate skeleton; polycaprolactone diol obtained by ring-opening addition reaction of lactones such as gamma-butyrolactone, epsilon-caprolactone and delta-valerolactone; bisphenol A, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, hydrogenated bisphenol A, ethylene oxide adducts of hydrogenated bisphenol A, propylene oxide adducts of hydrogenated bisphenol A, and other bisphenol A-based compounds may be used alone or in combination of 2 or more.
In order to obtain a liquid photosensitive resin composition excellent in the roll pressure dispersibility during coating and to improve the low resilience and fracture resistance of the obtained cured film, the diol compound represented by the general formula (1) is preferably a chain diol such as polyoxyalkylene diol, polyester diol, polycarbonate diol, polycaprolactone diol or the like.
As the diisocyanate compound represented by the general formula (2), examples thereof 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' -dimethoxydiphenylmethane-2, 4' -diisocyanate, diphenylmethane-4, 4' -diisocyanate, diphenylmethane-3, 3' -diisocyanate, diphenylmethane-3, 4' -diisocyanate, benzophenone-4, 4' -diisocyanate, diphenylsulfone-4, 4' -diisocyanate, xylylene-2, 4' -diisocyanate, 4' -xylylene-diisocyanate, 4' -diisocyanate, 4-xylylene-diisocyanate, hydrogenated [2, 4' -diisocyanate, 4' -xylylene-diisocyanate, 4' -xylylene-diisocyanate, and the like; alicyclic diisocyanate compounds such as isophorone diisocyanate and norbornene diisocyanate; aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and lysine diisocyanate, etc., and these may be used alone or in combination of 2 or more.
In particular, when one or more selected from the group consisting of alicyclic diisocyanate compounds and aliphatic diisocyanate compounds are used as the diisocyanate compound represented by the general formula (2), a liquid photosensitive resin composition excellent in photosensitivity is obtained, and is preferable.
In the synthesis of a polymer having a urethane bond in 1 molecule, it is preferable to compound the diol compound and the diisocyanate compound such that the ratio of the number of hydroxyl groups to the number of isocyanate groups is not less than 0.5 and not more than 2.0 per hydroxyl group.
In the case where 2 or more diol compounds are used, the reaction with the diisocyanate compound may be performed after mixing 2 or more diol compounds, or each diol compound may be reacted with the diisocyanate compound separately. Further, after the diol compound and the diisocyanate compound are reacted, the resulting terminal isocyanate compound may be further reacted with another diol compound, and the reaction product may be further reacted with another diisocyanate compound. The same applies to the case of using 2 or more diisocyanate compounds. In this way, a desired polymer having a urethane bond in 1 molecule can be synthesized.
The reaction temperature of the diol compound and the diisocyanate compound is preferably 40 ℃ to 160 ℃ and more preferably 60 ℃ to 150 ℃ from the viewpoints of shortening the reaction time and suppressing gelation. The reaction time of the diol compound and the diisocyanate compound may be appropriately selected depending on the amount of the starting material and the reaction conditions employed. If necessary, a compound containing a metal such as an alkali metal, an alkaline earth metal, tin, zinc, titanium, cobalt, or the like, and a semimetal; the reaction is carried out in the presence of a catalyst such as tertiary amines.
The reaction of the diol compound and the diisocyanate compound may be carried out without using a solvent, but in order to control the reaction, it is preferable to carry out the reaction in an organic solvent. The organic solvent used herein is not particularly limited, and for example, an organic solvent exemplified for the specific examples of the component (G) described later can be used.
In order to improve the reactivity of the polymerization reaction, the amount of the organic solvent used in the reaction is preferably an amount such that the concentration of the solute in the reaction solution is 5% by weight or more and 90% by weight or less. The 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 1 molecule is obtained by, for example, polymerizing one or more monomers selected from the group consisting of a compound represented by the following general formula (4) (hereinafter, sometimes referred to as "compound (4)") and a compound represented by the following general formula (5) (hereinafter, sometimes referred to as "compound (5)") in addition to a diol compound and a diisocyanate compound.
In the general formula (4), m represents an integer of 1 to 3 inclusive, R 2 Represents an m+1 valent organic group, R 3 Represents a hydrogen atom or a methyl group.
In the general formula (5), n represents an integer of 1 to 3 inclusive, X 2 Represents an n+1 valent organic group, X 3 Represents a hydrogen atom or a methyl group.
Examples of the compound (4) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-1-acryloyloxy-3-methacryloyloxy propane, o-phenylphenol glycidyl ether (meth) acrylate, polyethylene glycol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, 1, 4-cyclohexanedimethanol mono (meth) acrylate, 4-hydroxyphenyl (meth) acrylate, and 2- (4-hydroxyphenyl) ethyl (meth) acrylate, which may be used singly or in combination of 2 or more.
Examples of the compound (5) include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1- (bisacrylyloxymethyl) ethyl isocyanate, and 2- (2-methacryloyloxyethoxy) ethyl isocyanate, which may be used alone or in combination of 2 or more.
The polymer having a urethane bond and a carboxyl group in 1 molecule is obtained by, for example, performing a polymerization reaction using a compound represented by the following general formula (6) (hereinafter, sometimes referred to as "compound (6)") as a monomer in addition to a diol compound and a diisocyanate compound.
In the general formula (6), R 4 Represents a 3-valent organic group.
Examples of the compound (6) include 2, 2-bis (hydroxymethyl) propionic acid, 2-bis (2-hydroxyethyl) propionic acid, 2-bis (3-hydroxypropyl) propionic acid, 2, 3-dihydroxy-2-methylpropanoic acid, 2-bis (hydroxymethyl) butyric acid, 2-bis (2-hydroxyethyl) butyric acid, 2-bis (3-hydroxypropyl) butyric acid, 2, 3-dihydroxybutyric acid, 2, 4-dihydroxy-3, 3-dimethylbutyric 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, and 3, 5-dihydroxybenzoic acid, and the like, and these compounds may be used singly or in combination of 2 or more.
In order to enhance the photosensitivity of the liquid photosensitive resin composition, an aliphatic compound (6) is preferably used.
The polymer having a urethane bond and an imide group in 1 molecule is obtained, for example, by polymerization using tetracarboxylic dianhydride as a monomer in addition to a diol compound and a diisocyanate compound.
Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3', 4' -biphenyl tetracarboxylic dianhydride, p-phenylene bis (trimellitate anhydride), 2,3,6, 7-naphthalene tetracarboxylic dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, 2', 3' -biphenyl tetracarboxylic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 4 '-oxydiphthalic anhydride, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride, 4' - (hexafluoroisopropylidene) diphthalic anhydride, dicyclohexyl-3, 3', 4' -tetracarboxylic dianhydride, 1,2,4, 5-cyclohexane tetracarboxylic dianhydride, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, 2-bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, and the like may be used alone or in combination of 2 or more.
(1 Polymer having imide groups in the molecule)
"Polymer having imide groups in 1 molecule" refers to a polymer having at least 1 imide group in 1 molecule. Examples of the polymer having an imide group in the 1 molecule include polymers having a urethane bond and an imide group in the 1 molecule described above. Further, for example, a polymer having an imide group in 1 molecule can be obtained by reacting a tetracarboxylic dianhydride (more specifically, a compound exemplified as a tetracarboxylic dianhydride used for synthesizing the polymer having a urethane bond and an imide group in 1 molecule described above) with a diamine.
Examples of diamines which are starting materials for obtaining polymers having imide groups in the 1 molecule include p-phenylenediamine, 4 '-diaminoanilide, 2' -bis (trifluoromethyl) benzidine, 9-bis (4-aminophenyl) fluorene, 4-aminophenyl-4-aminobenzoate, 1, 4-diaminocyclohexane, m-phenylenediamine, 4 '-diaminodiphenyl ether, 3,4' -diaminodiphenyl ether, 2 '-bis (trifluoromethyl) -4,4' -diaminodiphenyl ether, N, N '-bis (4-aminophenyl) terephthalamide, 4' -diaminodiphenyl sulfone, m-tolidine, o-tolidine, 4 '-bis (4-aminophenoxy) biphenyl, 2- (4-aminophenyl) -6-aminobenzoxazole, 3, 5-diaminobenzoic acid, 4' -diamino-3, 3 '-dihydroxybiphenyl, 4' -methylenebis (cyclohexylamine), 1, 3-bis (3-aminopropyl) tetramethyldisiloxane and the like, which may be used alone or in combination of 2 or more.
The method for reacting the tetracarboxylic anhydride with the diamine is not particularly limited, and examples thereof include the methods shown in the following methods 1 to 3.
Method 1: a polyamide acid solution is produced by adding diamine to a solution obtained by dispersing or dissolving tetracarboxylic dianhydride in an organic solvent and reacting the mixture. The total amount of diamine to be added is preferably adjusted so that a ratio of 0.50 mol or more and 1.50 mol or less is formed with respect to 1 mol of tetracarboxylic dianhydride. After the reaction of the tetracarboxylic dianhydride and the diamine is completed, the obtained polyamic acid solution is heated to 100℃or higher and 300℃or lower, and more preferably 150℃or higher and 250℃or lower, to effect imidization.
Method 2: a polyamic acid solution was produced by the same method as in the above-mentioned method 1. Imidization is performed by adding an imidization catalyst (preferably, a tertiary amine such as pyridine, picoline, isoquinoline, trimethylamine, triethylamine, tributylamine, etc.) and a dehydrating agent (acetic anhydride, etc.) to the produced polyamic acid solution, and heating the solution to 60 to 180 ℃.
Method 3: a polyamic acid solution was produced by the same method as in the above-mentioned method 1. The produced polyamic acid solution is put into a vacuum oven set at 100 ℃ or higher and 250 ℃ or lower, and heated under reduced pressure to imidize.
(1 Polymer having (meth) acryloyl group in molecule)
"Polymer having a (meth) acryloyl group in a 1-molecule" refers to a polymer having at least 1 (meth) acryloyl group in a 1-molecule. Examples of the polymer having a (meth) acryloyl group in 1 molecule include the above-mentioned polymer having a urethane bond and a (meth) acryloyl group in 1 molecule. Further, for example, a polymer having a (meth) acryloyl group in 1 molecule can be obtained by reacting an epoxy resin with (meth) acrylic acid.
Examples of the epoxy resin as a raw material for obtaining a polymer having a (meth) acryloyl group in 1 molecule include 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 novolac type epoxy resin, cresol novolac type epoxy resin, triphenol methane type epoxy resin, dicyclopentadiene type epoxy resin, amine type epoxy resin, flexible epoxy resin, urethane modified epoxy resin, rubber modified epoxy resin, chelate modified epoxy resin, heterocyclic ring-containing epoxy resin, and the like, which may be used alone or in combination of 2 or more.
Specific examples of bisphenol a type epoxy resins include a product name jER 828 manufactured by Mitsubishi Chemical Corporation, a product name jER 1001 manufactured by jER 1002, a product name ADEKARESIN (registered trademark) EP-4100E manufactured by ADEKA corporation, a product name EP-4300E manufactured by ADEKA RESIN (registered trademark), a product name epicon 840S, epiclon S, epiclon manufactured by RE-310S, RE-410S, DIC corporation, an epicon 7050, NIPPON STEEL Epoxy Manufacturing co, a product name epoote YD-115 manufactured by ltd, an epoote YD-127, and an epoote YD-128 manufactured by epoote corporation.
Specific examples of bisphenol F type epoxy resins include Mitsubishi Chemical Corporation trade names jER (registered trademark) 806, jER (registered trademark) 807, ADEKA trade name ADEKA RESIN (registered trademark) EP-4901E, ADEKA RESIN (registered trademark) EP-4930, ADEKA RESIN (registered trademark) EP-4950, japanese chemical Co., ltd. Trade names RE-303S, RE-304S, RE-403S, RE-404S, DIC trade names Epiclon830, epiclon835, NIPPON STEEL Epoxy Manufacturing Co., ltd. Trade names Epote (registered trademark) YDF-170, epote (registered trademark) YDF-175S, epotote (registered trademark) YDF-2001, and the like.
As a specific example of bisphenol S type epoxy resin, epiclon EXA-1514 manufactured by DIC company and the like are cited.
Specific examples of the hydrogenated bisphenol A type epoxy resin include a product name of jER (registered trademark) YX8000, a product name of jER (registered trademark) YX8034, a product name of jER (registered trademark) YL7170, a product name of ADEKA RESIN (registered trademark) EP-4080E, DIC, a product name of Epiclon EXA-7015, NIPPON STEEL Epoxy Manufacturing Co, a product name of Epotote (registered trademark) YD-3000, epotote (registered trademark) YD-4000D, and the like, manufactured by Mitsubishi Chemical Corporation.
Specific examples of the biphenyl type epoxy resin include a product name jER (registered trademark) YX4000 manufactured by Mitsubishi Chemical Corporation, a product name jER (registered trademark) YL6121H, jER (registered trademark) YL6640, a product name jER (registered trademark) YL6677 manufactured by japan chemical company, a product name NC-3000, NC-3000H, and the like.
Specific examples of the phenoxy epoxy resin include the trade names jER (registered trademark) 1256, jER (registered trademark) 4250, jER (registered trademark) 4275, etc. manufactured by Mitsubishi Chemical Corporation.
Specific examples of the naphthalene type epoxy resin include Epiclon HP-4032, epiclon HP-4700, epiclon HP-4200, and NC-7000L, manufactured by Japanese chemical Co., ltd.
Specific examples of the phenol novolac type epoxy resin include a trade name jER (registered trademark) 152 manufactured by Mitsubishi Chemical Corporation, a trade name jER (registered trademark) 154 manufactured by japan chemical company, a trade name EPPN (registered trademark) -201-L, DIC manufactured by the company epicenter n-740, epicenter n-770, NIPPON STEEL Epoxy Manufacturing co, and a trade name Epotote (registered trademark) YDPN-638 manufactured by ltd.
Specific examples of the cresol novolac type epoxy resin include EOCN (registered trademark) -1020, EOCN (registered trademark) -102S, EOCN (registered trademark) -103S, EOCN (registered trademark) -104S, DIC (registered trademark), epiclon N-660, epiclon N-670, epiclon N-680, and Epiclon N-695.
Specific examples of the triphenolmethane-type epoxy resin include EPPN (registered trademark) -501H, EPPN (registered trademark) -501HY, EPPN (registered trademark) -502H, manufactured by japan chemical Co., ltd.
Specific examples of the dicyclopentadiene type epoxy resin include XD-1000, which is a product of Japanese chemical Co., ltd, epiclonHP-7200, which is a product of DIC Co., ltd.
Specific examples of the amine-type epoxy resin include a product name jER (registered trademark) 604, jER (registered trademark) 630, NIPPON STEEL Epoxy Manufacturing co, a product name Epotote (registered trademark) YH-434, epotote (registered trademark) YH-434L, mitsubishi Gas Chemical Company, and a product name tetra (registered trademark) -X, TERRAD (registered trademark) -C, manufactured by inc.
Specific examples of the flexible epoxy resin include the trade names jER (registered trademark) 871 and jER (registered trademark) 872 manufactured by Mitsubishi Chemical Corporation, jER (registered trademark) YL7175 and jER (registered trademark) YL7217 manufactured by DIC corporation, and the trade names epilocon exa-4850 manufactured by DIC corporation.
Specific examples of the urethane-modified epoxy resin include trademark ADEKA RESIN (registered trademark) EPU-6, ADEKA RESIN (registered trademark) EPU-73, ADEKA RESIN (registered trademark) EPU-78-11, and the like, which are manufactured by ADEKA corporation.
Specific examples of the rubber-modified epoxy resin include trademark ADEKA RESIN (registered trademark) EPR-4023, ADEKA RESIN (registered trademark) EPR-4026, ADEKA RESIN (registered trademark) EPR-1309, and the like, which are manufactured by ADEKA corporation.
Specific examples of the chelate modified epoxy resin include EP-49-10 and ADEKARESIN (registered trademark) EP-49-20, which are manufactured by ADEKA corporation under the trade names ADEKA RESIN (registered trademark).
Specific examples of the heterocyclic ring-containing epoxy resin include TEPIC (registered trademark) which is a product of japanese chemical Co., ltd.
The method for reacting the epoxy resin with (meth) acrylic acid is not particularly limited, and examples thereof include a method in which (meth) acrylic acid and an esterification catalyst (for example, tertiary amine such as trimethylamine and triethylamine, phosphorus compound such as triphenylphosphine, imidazole compound such as 2-ethyl-4-methylimidazole, etc.) are added to a solution in which the epoxy resin is dispersed or dissolved in an organic solvent, and the reaction is carried out by heating to 40 ℃ to 120 ℃. The total amount of (meth) acrylic acid to be added is preferably adjusted so that a ratio of 0.1 mol or more and 1.0 mol or less is formed with respect to 1 mol of the epoxy group of the epoxy resin.
(1 Polymer having carboxyl groups in the molecule)
"Polymer having a carboxyl group in 1 molecule" refers to a polymer having at least 1 carboxyl group in 1 molecule. Examples of the polymer having a carboxyl group in 1 molecule include polymers having a urethane bond and a carboxyl group in 1 molecule, as described above. Further, for example, a polymer having a carboxyl group in 1 molecule can be obtained by reacting an epoxy resin with (meth) acrylic acid and then reacting with a polybasic acid anhydride.
Examples of the method for obtaining a polymer having a carboxyl group in 1 molecule by reacting an epoxy resin with (meth) acrylic acid and then with a polybasic acid anhydride include a method in which the reaction is performed by reacting an epoxy resin with (meth) acrylic acid by the above-mentioned method, then adding a polybasic acid anhydride, and heating to 60 ℃ to 150 ℃. The total amount of the polybasic acid anhydride to be added is preferably adjusted so that the acid value of the solid content obtained becomes 10mgKOH/g or more and 160mgKOH/g or less.
In addition to the above-described method, a polymer having a carboxyl group in 1 molecule can also be obtained by reacting (meth) acrylic acid with (meth) acrylic acid ester. The method for reacting (meth) acrylic acid with (meth) acrylic acid ester is not particularly limited, and examples thereof include a method in which (meth) acrylic acid and (meth) acrylic acid ester are subjected to radical polymerization in a solvent in the presence of a radical polymerization initiator.
The (meth) acrylic acid 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, stearyl (meth) acrylate, benzyl (meth) acrylate, and the like, which may be used alone or in combination of 2 or more. In order to improve the flexibility and chemical resistance of the cured film of the liquid photosensitive resin composition, one or more (meth) acrylic esters selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and benzyl (meth) acrylate are preferable.
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., which may be used alone or in combination of 2 or more.
In order to improve the reactivity of the polymerization reaction and to suppress the decrease in molecular weight of the resulting polymer, the amount of the radical polymerization initiator to be used is preferably 0.001 parts by weight or more and 5 parts by weight or less, more preferably 0.01 parts by weight or more and 1 part by weight or less, relative to 100 parts by weight of the monomer to be used.
In order to improve the reactivity of the polymerization reaction, the amount of the solvent used in the radical polymerization reaction is preferably an amount such that the concentration of the solute in the reaction solution is 5% by weight or more and 90% by weight or less. The 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 is preferably 20 ℃ to 120 ℃, more preferably 50 ℃ to 100 ℃ from the viewpoints of shortening the reaction time and suppressing gelation. The reaction time of the radical polymerization reaction may be appropriately selected depending on the amount of the starting material and the reaction conditions employed.
In order to suppress occurrence of defective appearance of the coating film and defective appearance of the substrate on which the coating film is formed, the content of the component (a) is preferably 10% by weight or more and 50% by weight or less, more preferably 20% by weight or more and 40% by weight or less, relative to the total amount of the liquid photosensitive resin composition.
Component { (B) }
The component (B) is not particularly limited, and examples thereof include Michler's ketone, 4' -bis (diethylamino) benzophenone, 4 '-tris (dimethylamino) triphenylmethane, 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-butylanthraquinone, 1, 2-benzo-9, 10-anthraquinone, methylanthraquinone, thioxanthone, 2, 4-diethylthioxanthone, 2-isopropylthioxanthone, 1-hydroxycyclohexylphenyl ketone, diacetylbenzyl, dibenzoyldimethanol, dibenzoyldiethanol, 4' -diazochalcone, 2-dimethoxy-1, 2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropane-1-one, 2-dibenzylamino-2- (4-methylbenzoyl) -2-dimethylbenzoyl-1-butanone, 2-dimethyl-2-4-phenylmethyl-2-butanone, 4-tri-phenyl-4-phenylphosphine-1-one, bis (2, 6-dimethoxybenzoyl) -2, 4-trimethylpentylphosphine oxide, (2, 4, 6-trimethylbenzoyl) diphenylphosphine oxide, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate and the like, which may be used alone or in combination of 2 or more.
In order to improve the reactivity and resolution of the photo radical polymerization, the content of the component (B) is preferably 0.5% by weight or more and 5% by weight or less, more preferably 0.8% by weight or more and 4% by weight or less, relative to the total amount of the liquid photosensitive resin composition.
Component { (C) }
The component (C) is not particularly limited as long as it is an epoxy compound having 2 or more epoxy groups in 1 molecule, and examples of the epoxy resin which is a raw material for obtaining a polymer having a (meth) acryloyl group in 1 molecule can be used.
The liquid photosensitive resin composition may contain a curing agent of component (C). In the case of using a polymer having an acid value of 10mgKOH/g or more (preferably a polymer having an acid value of 10mgKOH/g or more and 160mgKOH/g or less) as the component (A), the curing agent of the component (C) may not be blended into the liquid photosensitive resin composition. (A) The acid value of the component (a) can be adjusted by, for example, changing the amount of the monomer having one or more groups selected from the group consisting of a carboxyl group and a carboxylic anhydride group to be charged when the component (a) is synthesized.
In order to improve the flexibility and chemical resistance of the resulting cured film, the content of the component (C) is preferably 1% by weight or more and 10% by weight or less, more preferably 3% by weight or more and 8% by weight or less, relative to the total amount of the liquid photosensitive resin composition.
Component { (D)
The component (D) is not particularly limited, and examples thereof include phosphine compounds such as triphenylphosphine; amine compounds such as triethanolamine, and melamine; borate compounds such as 1, 8-diazabicyclo [5,4,0] -7-undecene tetraphenyl borate; imidazole compounds such as imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2-isopropylimidazole, 2, 4-dimethylimidazole, and 2-phenyl-4-methylimidazole; imidazoline compounds such as 2-methylimidazoline, 2-ethylimidazoline, 2-isopropylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2, 4-dimethylimidazoline, and 2-phenyl-4-methylimidazoline; and triazine compounds such as 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, and 2, 4-diamino-6- (2 '-ethyl-4' -methylimidazolyl) ethyl-1, 3, 5-triazine, and the like, and these compounds may be used singly or in combination of 2 or more.
In order to obtain a flexible printed board having more excellent plating solution resistance and discoloration resistance of the wiring, the component (D) is preferably an amine compound, more preferably melamine.
In order to obtain a flexible printed board having more excellent plating solution resistance and discoloration resistance of wiring, the content of the component (D) is preferably 0.01 to 1.0 parts by weight, more preferably 0.01 to 0.5 parts by weight, still more preferably 0.1 to 0.5 parts by weight, particularly preferably 0.2 to 0.4 parts by weight, based on 100 parts by weight of the component (a).
Component { (E)
(E) The component (c) is blended into the liquid photosensitive resin composition as a component capable of undergoing photo radical polymerization. The component (E) is not particularly limited as long as it is a radical polymerizable compound having 3 or more radical polymerizable groups (functional groups that undergo polymerization reaction by a radical polymerization initiator) in 1 molecule, and is preferably a radical polymerizable compound having 3 or more and 6 or less radical polymerizable groups in 1 molecule in order to obtain a flexible printed board that ensures flexibility of a cured film and is excellent in plating solution resistance and discoloration resistance of wiring. The component (E) is preferably a compound having a molecular weight (weight average molecular weight in the case of a polymer) of less than 1000. Examples of the radical polymerizable group contained in the component (E) include a group having an unsaturated double bond. In order to improve radical polymerizability, a (meth) acryl group or vinyl group is preferable as the radical polymerizable group.
Specific examples of the component (E) include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, trimethylolpropane tetraacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethylacrylate, trimethylolpropane tetramethacrylate, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, tris (ethane acrylate) isocyanurate, pentaerythritol tetraacrylate, bis (trimethylolpropane) tetraacrylate, caprolactone-modified dipentaerythritol hexaacrylate, ethoxylated dipentaerythritol hexaacrylate, triallyl isocyanurate, 1,3, 5-triacryloylhexahydro-s-triazine, and the like, which may be used alone or in combination of 2 or more.
In order to obtain a flexible printed board having more excellent plating solution resistance and discoloration resistance of the wiring, the content of the component (E) is preferably 1% by weight or more and 10% by weight or less, more preferably 3% by weight or more and 8% by weight or less, relative to the total amount of the liquid photosensitive resin composition.
Component { (F)
The component (F) is not particularly limited as long as it is particles having an average particle diameter of 0.01 μm or more and 100 μm or less, and for example, one or more particles selected from the group consisting of inorganic particles and organic particles may be used. By blending the component (F) into the liquid photosensitive resin composition, the viscosity and thixotropic properties of the liquid photosensitive resin composition can be adjusted.
In order to improve the resolution of the liquid photosensitive resin composition and to improve the flexibility and chemical resistance of the resulting cured film, the average particle diameter of the component (F) is preferably 0.01 μm or more and 50 μm or less, more preferably 0.01 μm or more and 10 μm or less.
Specific examples of the component (F) include particles of an inorganic substance such as silica, mica, talc, clay, barium titanate, barium sulfate, wollastonite, calcium carbonate, magnesium carbonate, aluminum oxide, titanium oxide, silicon nitride, and aluminum nitride; particles of organic substances such as core-shell rubbers and crosslinked polymers may be used alone or in combination of 2 or more.
The inorganic particles are preferably silica particles in view of suppressing the curing shrinkage of the obtained cured film and improving the hardness and adhesion of the obtained cured film. Examples of the silica particles include fused silica particles, crushed silica particles, spherical silica particles, crystalline silica particles, and fumed silica particles.
The organic particles are preferably crosslinked polymer particles, more preferably crosslinked polymer particles having an average particle diameter of 1 μm or more and 10 μm or less, from the viewpoints of improving the dispersibility of the roller during coating and improving the flexibility and chemical resistance of the resulting cured film. Specific examples of the crosslinked polymer particles include DAIMICBEAZ (registered trademark) UCN-8070CM Clear, UCN-8150CM Clear, UCN-5070D Clear, UCN-5150DClear, art Pearl (registered trademark) C-100 Clear, C-200 Clear, C-300WA, C-400 Clear, C-400WA, C-600 Clear, C-800WA, C-1000T, P-400T, P-800T, U-600T, CF-600T, JB-400T, JB-800T, CE-400T, CE-800T, MM-120T, etc., which are available singly or in combination of 2 or more.
In order to further improve the flexibility of the resulting cured film, polyurethane particles are preferably used as the component (F). In order to improve the dispersibility of the roll pressure during coating and further improve the flexibility of the resulting cured film, it is preferable to use crosslinked polyurethane particles as the crosslinked polymer particles as the component (F).
In order to further suppress occurrence of appearance defects in the coating film and appearance defects in the substrate on which the coating film is formed, the content of the component (F) is preferably 5 parts by weight or more and 100 parts by weight or less, more preferably 5 parts by weight or more and 80 parts by weight or less, still more preferably 10 parts by weight or more and 80 parts by weight or less, still more preferably 20 parts by weight or more and 80 parts by weight or less, relative to 100 parts by weight of the component (a).
Component { (G)
(G) The component (c) is used for adjusting the viscosity of the liquid photosensitive resin composition. Examples of the component (G) include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide; acetamide 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, and the like. Further, these organic solvents and aromatic hydrocarbons (more specifically, xylene, toluene, etc.) may be used in combination as needed.
As the component (G), a symmetrical glycol diether-based solvent such as 1, 2-dimethoxyethane, bis (2-methoxyethyl) ether, bis [2- (2-methoxyethoxyethyl) ] ether, 1, 2-diethoxyethane, bis (2-ethoxyethyl) ether, or bis (2-butoxyethyl) ether may be used; acetic acid ester solvents such as 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-methoxybutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol diacetate, and 1, 3-butanediol diacetate; ether solvents such as 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, triethylene glycol dimethyl ether, and the like.
In order to easily adjust the viscosity of the liquid photosensitive resin composition to a range suitable for coating, the content of the component (G) is preferably 10% by weight or more and 80% by weight or less, more preferably 20% by weight or more and 70% by weight or less, relative to the total amount of the liquid photosensitive resin composition.
{ other Components }
The liquid photosensitive resin composition may contain, as necessary, various additives such as a radical polymerizable compound having 2 radical polymerizable groups in 1 molecule, a flame retardant, an antifoaming agent, a leveling agent, a colorant, an adhesion promoter, and a polymerization inhibitor as other components (components different from the components (a) to (G)). 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.
The radical polymerizable compound having 2 radical polymerizable groups in the molecule (hereinafter, sometimes referred to as "specific radical polymerizable compound") is preferably a compound having a molecular weight (weight average molecular weight in the case of a polymer) of less than 1000. Examples of the radical polymerizable group included in the specific radical polymerizable compound include a group having an unsaturated double bond. In order to improve radical polymerizability, a (meth) acryl group or vinyl group is preferable as the radical polymerizable group.
Specific examples of the specific radical polymerizable compound are listed below. In the following, ethylene oxide is referred to as "EO". The average molar number of EO added is referred to as "n". Specific examples of the specific radical polymerizable compound include EO-modified bisphenol F diacrylate (n: 2 to 50), EO-modified bisphenol A diacrylate (n: 2 to 50), EO-modified bisphenol S diacrylate (n: 2 to 50), EO-modified bisphenol F dimethacrylate (n: 2 to 50), EO-modified bisphenol A dimethacrylate (n: 2 to 50), EO-modified bisphenol S dimethacrylate (n: 2 to 50), 1, 6-hexanediol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, pentaerythritol diacrylate, tetraethylene glycol diacrylate, 1, 6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol dimethacrylate, tetraethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, 1, 3-butanediol dimethacrylate, 1, 6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, 1, 4-pentanediol dimethacrylate, 1, 5-propanediol dimethacrylate, 1, 4-propanediol dimethacrylate, 5-pentanediol, 1, 5-propanediol dimethacrylate, 1, 5-pentanediol dimethacrylate, 1, 5-propanediol dimethacrylate, and the specific radical polymerizable compound, diallyl dimethyl silane, diallyl disulfide, diallyl ether, diallyl isophthalate, diallyl terephthalate, and the like, which may be used alone or in combination of 2 or more.
In order to obtain a flexible printed board having more excellent plating solution resistance and discoloration resistance of wiring, the specific radical polymerizable compound is preferably at least one selected from the group consisting of 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).
In order to obtain a flexible printed board having more excellent plating solution resistance and discoloration resistance of the wiring, the content of the specific radical polymerizable compound is preferably 1% by weight or more and 10% by weight or less relative to the total amount of the liquid photosensitive resin composition.
Examples of the flame retardant include halogen flame retardants, phosphorus flame retardants, metal hydroxides, and antimony flame retardants.
The halogen flame retardant means a compound having at least 1 halogen atom in 1 molecule and inhibiting the combustion of an organic substance. Examples of the halogen flame retardant include bromine compounds and chlorine compounds, and they may be used alone or in combination of 2 or more.
The phosphorus flame retardant means a compound having at least 1 phosphorus atom in 1 molecule and suppressing the combustion of an organic substance. Examples of the phosphorus flame retardant include red phosphorus, condensed phosphate compounds, cyclic organic phosphorus compounds, phosphazene compounds, phosphorus-containing polyol compounds, phosphorus-containing amine compounds, ammonium polyphosphate, melamine phosphate, phosphinate, and the like, and these may be used alone or in combination of 2 or more.
Examples of the metal hydroxide functioning as a flame retardant include aluminum hydroxide and magnesium hydroxide, and these may be used alone or in combination of 2 or more.
The antimony flame retardant is a compound having at least 1 antimony atom in 1 molecule and inhibiting the combustion of an organic substance. Examples of the antimony flame retardant include antimony trioxide.
Examples of the defoaming agent include an acrylic compound, a vinyl compound, and a butadiene compound.
Examples of the leveling agent include an acrylic compound and a vinyl compound.
Examples of the colorant include phthalocyanine compounds, azo compounds, and carbon black.
Examples of the adhesion promoter (also referred to as an adhesion imparting agent) include a silane coupling agent, a triazole compound, a tetrazole compound, and a triazine compound.
Examples of the polymerization inhibitor include hydroquinone and hydroquinone monomethyl ether.
[ method for producing liquid photosensitive resin composition ]
The liquid photosensitive resin composition can be produced by pulverizing, dispersing and mixing the above components (a) to (E) and optional components ((F) component, (G) component, the above other components, etc.) as needed. The pulverizing/dispersing method is not particularly limited, and examples thereof include a method using a kneading apparatus such as a bead mill, a ball mill, or a three-roll mill. Among them, the method of pulverizing, dispersing and mixing using a three-roll mill is preferable because the particle size distribution becomes uniform.
[ optional procedure ]
In this embodiment, the steps of drying the substrate (drying step) are arbitrary steps except for the step of applying the liquid photosensitive resin composition. Examples of the optional step include a fine opening forming step, a curing step, a gold plating step, a hot pressing step, and a baking step, which are described below, in addition to the drying step.
(step of forming micro-openings)
The coating film after the drying step is irradiated with active energy rays (more specifically, ultraviolet rays, visible rays, electron beams, and the like) through a negative photomask, and a part of the coating film is exposed. This allows the component to polymerize in the exposed portion of the coating film by photo radical polymerization. The unexposed portion is then rinsed with a developer by a developing means such as spraying, stirring, dipping, or ultrasonic, whereby the coating film is patterned to form fine openings. The time required for the opening is different depending on the spray pressure, flow rate, and temperature of the developer, so that it is preferable to appropriately find the most suitable device conditions.
As the developer, an alkaline aqueous solution is preferable. The developer may contain a water-soluble organic solvent such as methanol, ethanol, 1-propanol, 2-propanol, and N-methyl-2-pyrrolidone. Examples of the basic compound contained in the basic aqueous solution include hydroxides, carbonates, bicarbonates, and amine compounds of alkali metals, alkaline earth metals, and ammonium ions, and specifically include sodium hydroxide, potassium hydroxide, ammonium hydroxide, 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-dimethylethanolamine, triethanolamine, and triisopropylamine. 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 alkali developing solution, and is usually 0 ℃ or higher and 80 ℃ or lower, preferably 10 ℃ or higher and 60 ℃ or lower.
The fine openings formed by development are preferably washed internally to remove unused residual portions. Examples of the washing liquid include water and an acidic aqueous solution.
(curing step)
Next, a heat treatment is performed on the coating film (patterned coating film) in which the fine openings are formed. By performing a heat treatment to react reactive groups (for example, reactive groups of component (C)) remaining in the molecular structure of the coating film, a cured film having high heat resistance can be obtained. The thickness of the cured film is determined in consideration of the wiring thickness and the like, and is preferably 2 μm or more and 50 μm or less. In order to prevent oxidation of the wiring and the like and to prevent adhesion of the wiring to the film-like support from decreasing, the final curing temperature in the curing step is preferably a low temperature. The final curing temperature is preferably 100 ℃ to 250 ℃, more preferably 120 ℃ to 200 ℃, still more preferably 130 ℃ to 180 ℃. The curing time at the final curing temperature is, for example, 1 minute to 120 minutes. The cured film formed by this embodiment has excellent flexibility, flame retardancy, and electrical insulation reliability, and tends to have reduced warpage after the curing process. Therefore, the cured film formed by this embodiment is particularly suitable as an insulating material for a flexible printed board.
(gold plating step)
Then, a gold plating step is performed on the substrate on which the cured film is formed (hereinafter, sometimes referred to as "substrate with cured film"). The gold plating step includes, for example, a degreasing step, an etching step, a catalyst treatment step, an electroless nickel plating step, and an electroless gold plating step.
The electroless gold plating solution that can be used in the electroless gold plating process includes gold salts such as potassium gold cyanide, potassium gold sulfite, and sodium gold sulfite; buffering agents such as organic acid salts, sulfate salts, boric acid, phosphate salts, sulfamic acid, and the like; metal masking agents such as ethylenediamine tetraacetic acid, N '- (2-hydroxyethyl) ethylenediamine-N, N' -triacetic acid, nitrilotriacetic acid, diethylenetriamine pentaacetic acid, triethylenetetramine hexaacetic acid, and the like; crystal modifiers such as cobalt, nickel, silver, iron, palladium, copper, thallium, lead, and arsenic. Examples of such electroless GOLD plating solutions include, for example, the trade names FLASH GOLD 2000, FLASH GOLD VT, FLASH GOLD 330, FLASH GOLD NC, electroless Noble AU, SELF GOLD OTK-IT, the trade names GOBRIGHT TMX-22, GOBRIGHT TMX-23, GOBRIGHT TMX-40, GOBRIGHT TSB-71, GOBRIGHT TSB-72, GOBRIGHT TCU-37, GOBRIGHT TUC-38, GOBRIGHT TAM-LC, GOBRIGHT TCL-61, GOBRIGHT TIG-10, GOBRIGHT TAW-66, and AURICAL (registered trade mark) TKK-51 manufactured by OIL.
(Hot pressing Process)
Next, the substrate with the cured film after the gold plating step and a plate-like or film-like member (specifically, a reinforcing plate, an electromagnetic wave shielding film, or the like) are laminated by heat press treatment. The hot pressing method that can be used in the hot pressing step is not particularly limited, and examples thereof include a usual hot pressing method used for processing flexible printed boards, such as multi-stage lamination hot pressing and rapid pressing. In order to further suppress discoloration of the wiring, the hot pressing temperature in the hot pressing step is preferably 120 ℃ or higher and 200 ℃ or lower, more preferably 150 ℃ or higher and 180 ℃ or lower. The hot pressing time in the hot pressing step is, for example, 30 minutes to 90 minutes.
(baking step)
Subsequently, the laminate obtained in the hot pressing step is baked. As a baking treatment method that can be used in the baking step, a general baking treatment method used in processing a flexible printed board, such as a heating method using a box oven or a tunnel oven, is exemplified. In order to further suppress discoloration of the wiring, the baking temperature in the baking step is preferably 120 ℃ or higher and 200 ℃ or lower, more preferably 140 ℃ or higher and 180 ℃ or lower. The baking time in the baking step is, for example, 60 minutes to 120 minutes. The flexible printed board is obtained through the above steps.
Examples
The present invention will be specifically described below by way of examples, but the present invention is not limited to these examples.
First, a method for measuring the weight average molecular weight and the acid value of the binder polymers P1 to P3 and the solid content concentration of the resin solutions SP1 to SP3 containing the binder polymers P1 to P3, respectively, will be described.
Method for measuring weight average molecular weight
The weight average molecular weights of the binder polymers P1 to P3 were measured under the following conditions.
Use device: TOSOH CORPORATION "HLC-8220GPC"
Chromatographic column: TOSOH CORPORATION "TSKgel Super AWM-H" (6.0 mm I.D..times.15 cm). Times.2 roots)
Protection column: TOSOH CORPORATION "TSKguardcolumn Super AW-H". Times.1 roots
Eluent: liBr (concentration: 30 mmol/L) and H were dissolved 3 PO 4 (concentration: 20 mmol/L) of N, N-dimethylformamide solution
Flow rate: 0.6 mL/min
Column temperature: 40 DEG C
Detector: RI (differential refractometer)
Detection conditions of RI: polarity (+), response (0.5 seconds)
Sample concentration: 5mg/mL
Standard: PEG (polyethylene glycol)
< method for measuring acid value >)
The acid values of the binder polymers P1 to P3 were measured by the method described in JIS K5601-2-1 (1999).
Method for measuring solid content concentration of resin solution
The solid content concentrations of the resin solutions SP1 to SP3 were measured by the method described in JIS K5601-1-2 (2008). The drying conditions at the time of measurement were 170℃for 1 hour.
< production of resin solution >
The following describes a method for producing the resin solutions SP1 to SP3 containing the binder polymers P1 to P3 as the component (a), respectively. The reaction (stirring) was performed under a nitrogen gas stream unless otherwise specified.
[ production of resin solution SP1 containing Binder Polymer P1 ]
35.00g of triethylene glycol dimethyl ether (hereinafter sometimes referred to as "TEGDM") and 10.31g (0.050 mol) of norbornene diisocyanate were charged into a reaction vessel equipped with a stirrer, a thermometer and a nitrogen inlet pipe, and the contents of the vessel were heated to 80℃while stirring under a nitrogen stream to dissolve norbornene diisocyanate in TEGDM. Then, after adding a TEGDM solution of polycarbonate diol (PCDL T5652, manufactured by Asahi Kabushiki Kaisha, weight average molecular weight: 2000) to the container contents for 1 hour, the resulting solution was heated to 80℃and stirred for 2 hours. The TEGDM solution of the polycarbonate diol was obtained by dissolving 50.00g (0.025 mol) of the polycarbonate diol in 35.00g of TEGDM. 15.51g (0.050 moles) of 4,4' -oxydiphthalic anhydride was then added to the vessel contents, and the vessel contents were stirred for 1 hour while heating to 190 ℃. After the vessel contents were cooled to 80 ℃, 3.60g (0.200 mol) of pure water was added to the vessel contents. Then, the vessel content was refluxed for 5 hours while being heated to 110℃to obtain a resin solution SP1 containing 1 molecule of the binder polymer P1 having a urethane bond and an imide group. The solid content concentration of the obtained resin solution SP1 was 53 wt%. In addition, the weight average molecular weight and acid value of the binder polymer P1 were 9200 and 86mgKOH/g, respectively.
[ production of resin solution SP2 containing Binder Polymer P2 ]
40.00g of TEGDM and 20.62g (0.100 mol) of norbornene diisocyanate as a solvent for polymerization were charged into a reaction vessel equipped with a stirrer, a thermometer and a nitrogen inlet pipe, and the vessel contents were stirred under a nitrogen flow and heated to 80℃to dissolve the norbornene diisocyanate in the TEGDM. Next, a TEGDM solution of polycarbonate diol (PCDL T5652, manufactured by Asahi Kabushiki Kaisha, weight average molecular weight: 2000), 2-bis (hydroxymethyl) butyric acid and 2-hydroxyethyl methacrylate was added to the container contents for 1 hour. The resulting solution was heated to 80℃while stirring for 5 hours, to obtain a resin solution SP2 containing 1 molecule of the binder polymer P2 having urethane bonds, carboxyl groups and methacryloyl groups. The TEGDM solution of the polycarbonate diol, 2-bis (hydroxymethyl) butyric acid and 2-hydroxyethyl methacrylate was a solution prepared by dissolving 50.00g (0.025 mol) of the polycarbonate diol, 3.70g (0.025 mol) of 2, 2-bis (hydroxymethyl) butyric acid and 13.02g (0.100 mol) of 2-hydroxyethyl methacrylate in 40.00g of TEGDM. The solid content concentration of the obtained resin solution SP2 was 52 wt%. In addition, the weight average molecular weight and acid value of the binder polymer P2 were 8600 and 18mgKOH/g, respectively.
[ production of resin solution SP3 containing Binder Polymer P3 ]
100.00g of TEGDM as a solvent for polymerization was charged into a reaction vessel equipped with a stirrer, a thermometer and a nitrogen inlet tube, and the vessel contents were heated to 80℃while stirring under a nitrogen flow. Next, it took 3 hours to drop the mixture containing the methacrylic compound into the reaction vessel using a dropping funnel while maintaining the temperature of the vessel contents at 80 ℃. The mixture containing the methacrylic compound was a mixture of 12.0g (0.14 mol) of methacrylic acid, 28.0g (0.16 mol) of benzyl methacrylate, 60.0g (0.42 mol) of butyl methacrylate, and 0.5g of azobisisobutyronitrile as a radical polymerization initiator, which were previously mixed in an atmosphere at a temperature of 25 ℃. After the completion of the dropwise addition, the vessel contents were heated to 90℃while stirring. Then, the vessel contents were stirred for 2 hours while keeping the temperature of the vessel contents at 90℃to obtain a resin solution SP3 containing 1 molecule of the binder polymer P3 having a carboxyl group. The solid content concentration of the obtained resin solution SP3 was 50 wt%. In addition, the weight average molecular weight and acid value of the binder polymer P3 were 48000 and 78mgKOH/g, respectively.
Production of liquid photosensitive resin composition
Any one of the resin solutions SP1 to SP3 obtained by the above-described production method and each component (specifically, component other than the component (a)) described in tables 1 to 4 described later are mixed by a stirring device having stirring blades. Next, the obtained mixture was subjected to three-roll milling 2 times, and then defoamed by a deaeration device, to obtain liquid photosensitive resin compositions used in examples 1 to 14 and comparative examples 1 to 3, respectively. The average particle diameter of the particles in the obtained liquid photosensitive resin composition was measured, and as a result, it was 10 μm or less for any one of examples 1 to 14 and comparative examples 1 to 3.
Method for measuring physical properties of liquid photosensitive resin composition, and method for evaluating liquid photosensitive resin composition
[ method for evaluating micro-opening Property ]
Each liquid photosensitive resin composition was applied onto a portion (region of 200mm×200mm in area) of a polyimide film (manufactured by Kaneka Corporation under the trade name "apial (registered trademark) 25 NPI") having a thickness of 25 μm using a Baker applicator. At this time, the coating amount of the liquid photosensitive resin composition was adjusted so that the thickness of the cured film was 20. Mu.m. Then, the coating film formed from the liquid photosensitive resin composition was dried at a drying temperature of 80℃for 20 minutes, and then, a cumulative exposure of 300mJ/cm was carried out by a negative photomask having a light-shielding region in the shape of a circle having diameters of 30 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm and 200 μm 2 The coating film is exposed to ultraviolet rays. Next, a 1.0 wt% aqueous sodium carbonate solution (temperature: 30 ℃ C.) was used as a developer, and the pressure of the exposed coating film was set at 1.0kgf/mm 2 Is subjected to spray development for 90 seconds. Then, the developed coating film was washed with pure water, and then heated in an oven at a temperature of 150 ℃ 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 of the formed pores was used as an evaluation value for the fine-opening property.
[ method for measuring resilience ]
First, a flexible film was prepared by bonding an electrolytic copper foil (thickness: 12 μm) to both sides of a polyimide film (Kaneka Corporation "PIXEO (registered trademark)" BP FRS-522#SW ", thickness: 12.5 μm) as a film-like supportCopper laminate. The copper foil on one side of the flexible copper-clad laminate was patterned to form a comb-shaped pattern having a line width/space width=100 μm/100 μm on the film-like support. Next, the laminated plate having the comb-shaped pattern formed thereon was immersed in a 10 vol% sulfuric acid aqueous solution for 1 minute, and then washed with pure water. Each liquid photosensitive resin composition was then coated on the comb-shaped pattern 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 on the comb-shaped pattern was 20. Mu.m. Then, the coating film formed from the liquid photosensitive resin composition was dried at a drying temperature of 80℃for 20 minutes, and then, the film was exposed to a cumulative exposure of 300mJ/cm 2 The whole surface of the coating film is irradiated with ultraviolet rays for exposure. Next, a 1.0 wt% aqueous sodium carbonate solution (temperature: 30 ℃ C.) was used as a developer, and the pressure of the exposed coating film was set at 1.0kgf/mm 2 Is subjected to spray development for 90 seconds. Then, the developed coating film was washed with pure water, and then heated in an oven at a temperature of 150 ℃ for 60 minutes, to form a cured film of the liquid photosensitive resin composition on the comb-shaped pattern. The obtained laminate containing the cured film was cut into dimensions of 15mm in width by 200mm in length to obtain test pieces. The test piece was wound in a ring shape having an outer circumference of 50mm and fixed to a resilience measuring device (Loop Stiffness Tester (registered trademark) manufactured by Toyo Seiki Seisakusho Ltd.), and the test piece wound in a ring shape was inserted until the shortest ring diameter was 10mm, and resilience was measured from the test piece wound in a ring shape. The lower the rebound resilience, the better the low rebound resilience of the cured film can be evaluated.
[ evaluation method of solder Heat resistance ]
Each liquid photosensitive resin composition was coated on an electrolytic copper foil having a thickness of 35 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 was 20. Mu.m. Next, the coating film formed from the liquid photosensitive resin composition was dried at a drying temperature of 80℃for 20 minutes, and then, the film was exposed to a cumulative exposure of 300mJ/cm 2 The whole surface of the coating film is irradiated with ultraviolet rays for exposure. Then 1.0 weight was usedAn aqueous solution of sodium carbonate (temperature: 30 ℃ C.) at a discharge pressure of 1.0kgf/mm against the exposed coating film as a developing solution 2 Is subjected to spray development for 90 seconds. Then, the developed coating film was washed with pure water, and then heated in an oven at a temperature of 150 ℃ for 60 minutes, to form a cured film of the liquid photosensitive resin composition on the electrolytic copper foil, thereby obtaining a test piece. The test piece obtained was immersed in a solder bath at 260℃and then lifted up for 10 seconds, followed by 3 consecutive operations, which were performed as 1 operation. Then, the state of the cured film surface was visually observed, and the cured film surface was evaluated as "a (excellent solder heat resistance)", in the case where no swelling and peeling were confirmed. On the other hand, the cured film surface was evaluated as "B (solder heat resistance was not excellent)", in which swelling and peeling were confirmed.
[ evaluation method of Electrical insulation reliability ]
First, a flexible copper-clad laminate was prepared by bonding electrolytic copper foil (thickness: 12 μm) to both sides of a polyimide film (Kaneka Corporation "PIXEO (registered trademark)" BP FRS-142#SW ", thickness: 25 μm) as a film-like support. The copper foil on one side of the flexible copper-clad laminate was patterned to form a comb-shaped pattern having a line width/space width=100 μm/100 μm on the film-like support. Next, the laminated plate having the comb-shaped pattern formed thereon was immersed in a 10 vol% sulfuric acid aqueous solution for 1 minute, and then washed with pure water. Each liquid photosensitive resin composition was then coated on the comb-shaped pattern 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 on the comb-shaped pattern was 20. Mu.m. Then, the coating film formed from the liquid photosensitive resin composition was dried at a drying temperature of 80℃for 20 minutes, and then, the film was exposed to a cumulative exposure of 300mJ/cm 2 The whole surface of the coating film is irradiated with ultraviolet rays for exposure. Next, a 1.0 wt% aqueous sodium carbonate solution (temperature: 30 ℃ C.) was used as a developer, and the pressure of the exposed coating film was set at 1.0kgf/mm 2 Is subjected to spray development for 90 seconds. Next, the developed coating film was washed with pure water, and then heated in an oven at 150℃for 60 minutes to give a comb-shaped patternA cured film of the liquid photosensitive resin composition was formed thereon to obtain a test piece. Then, a direct current voltage of 100V was applied to both terminal portions of the test piece at a temperature of 85 ℃ and a relative humidity of 85%, and a change in resistance value between both terminal portions was observed. Next, 1.0X10 was shown when 1000 hours passed from the start of application 8 The resistance value of Ω or more was evaluated as "a (excellent electrical insulation reliability)". On the other hand, less than 1.0X10 when 1000 hours elapsed from the start of application 8 The resistance value of Ω was evaluated as "B (electrical insulation reliability is not excellent)".
< fabrication of substrate >)
First, a flexible copper-clad laminate was prepared by bonding electrolytic copper foil to both surfaces of a polyimide film (registered trademark "PIXEO" BP frs#sw "manufactured by Kaneka Corporation) as a film-like support. The flexible copper-clad laminate was provided with 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. Then, cleaning treatment (desmutting treatment) and carbon treatment are performed in the through-hole. Then, after the electrolytic copper plating treatment is performed in the through-hole, the electrolytic copper foil on both sides is patterned to form a wiring, and a substrate having a film-like support and wirings provided on both sides of the film-like support and provided with the through-hole is obtained. Tables 1 to 4, which will be described later, show the longitudinal width and the lateral width of the substrate used, the thickness of the film-like support used, and the thickness of the wiring of the substrate used, for examples 1 to 14 and comparative examples 1 to 3, respectively.
Coating of liquid photosensitive resin composition on substrate and formation of coating film
The liquid photosensitive resin composition (any one of the liquid photosensitive resin compositions described in tables 1 to 4 below) was applied to both sides of the substrate produced by the above steps using a vertical lift roll coater having a pair of application rolls. At this time, the liquid photosensitive resin composition is simultaneously applied to both surfaces of the substrate. The coating conditions are as follows. In the following coating conditions, "coating rolls" means "a pair of coating rolls" respectively.
Material of the top layer (top layer roller) of the applicator roller: ethylene propylene rubber
Width of skin layer roller: 680mm
Roll diameter of applicator roll: as described in tables 1 to 4 below
Type of slot of the applicator roll: a plurality of independent annular grooves
Spacing of the grooves of the applicator roll: 700 μm
Width of the opening of the slot of the applicator roll: 700 μm
Cross-sectional shape of the groove of the applicator roll: v-shape
Depth of the groove of the applicator roll: 350 μm
Pressure of the wiper blade: 1.5kgf/cm 2
The amount of the applicator roll inserted: 150 μm
Rotational speed of the applicator roll: 5 m/min
Next, the substrate coated with the liquid photosensitive resin composition was dried in a suspended state at a drying temperature of 80 ℃ for 20 minutes to obtain a dried substrate having a coating film formed from the liquid photosensitive resin composition (hereinafter, sometimes referred to as "substrate with coating film"). The thickness of the coating film formed from the liquid photosensitive resin composition after drying (specifically, the thickness of the coating film on the wiring except the periphery of the hole) was 20 μm on both sides.
Method for evaluating substrate with coating film
[ embedding Property ]
The maximum diameter of the through-holes (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) of each substrate with a coating film was observed by an optical microscope, and the filling ratio was 100% (when 600 through-holes were all filled) as an evaluation value of the embeddability. For example, "the evaluation value of the embeddability is 50 μm" means that all of 600 through holes are filled for through holes having diameters of 30 μm and 50 μm, but some or all of 600 through holes are not filled for through holes having diameters of 80 μm. Thus, the greater the evaluation value, the more excellent the embeddability can be evaluated.
[ appearance of coating film ]
The coated film of each substrate with the coated film was visually observed, and the presence or absence of pinholes, coating unevenness of the coated film covering the wiring, marks of the grooves of the coating roller, and ribbing was confirmed. Next, the appearance of the coating film was judged according to the following criteria. When A or B is determined, it is evaluated as "generation of defective appearance of the coating film can be suppressed". On the other hand, when C was determined, it was evaluated as "generation of appearance failure of the coating film could not be suppressed".
(criterion for determining appearance of coating film)
A: any of pinholes, uneven coverage, traces of grooves, and streaks were not confirmed.
B: at least 1 defect site among pinholes, uneven coverage, trace of grooves, and drawn streaks was confirmed to total 1 or 2.
C: at least 1 defect site among pinholes, uneven coverage, trace of grooves and streaks was confirmed to be 3 or more in total.
[ appearance of substrate with coating film ]
The appearance of each coated substrate was visually observed, and the presence or absence of cracking of the substrate and deformation of the substrate were confirmed. Next, the appearance of the substrate with the coating film was determined according to the following criteria. When a or B is determined, it is evaluated that "occurrence of defective appearance of the substrate with a coating film can be suppressed". On the other hand, when C was determined, it was evaluated as "the occurrence of defective appearance of the substrate with a coating film could not be suppressed".
(criterion for determining appearance of substrate with coating film)
A: neither the breakage of the substrate nor the deformation of the substrate was confirmed.
B: the breakage of the substrate was not confirmed, but the deformation of the substrate was confirmed.
C: both the breakage of the substrate and the deformation of the substrate were confirmed.
< formation of cured film >
The substrate with a coating film obtained by the above steps was processed by a method having a circular shape with a diameter of 150 μm 100 negative photomasks in the shading area of (a) and the cumulative exposure of 300mJ/cm 2 Ultraviolet rays are irradiated under the condition of (2) to expose the coating film. Next, a 1.0 wt% aqueous sodium carbonate solution (temperature: 30 ℃ C.) was used as a developer, and the pressure of the exposed coating film was set at 1.0kgf/mm 2 Is subjected to spray development for 90 seconds. Next, the developed coating film was washed with pure water, and then heated in an oven at a temperature of 150 ℃ for 60 minutes, thereby forming a cured film of the liquid photosensitive resin composition, and a substrate provided with a cured film of a protective wiring (hereinafter sometimes referred to as a "substrate with a cured film") was obtained. 100 circular openings were formed in the cured film of the obtained substrate with the cured film. Further, a part of the wiring is exposed from the opening of each circular shape.
Method for evaluating substrate with cured film
[ thickness of cured film around hole ]
After cutting the substrate with a cured film obtained by the method described in < formation of cured film > in the thickness direction, the obtained chips were embedded with an epoxy-based embedding resin, and the cross sections of the embedded chips were polished with a cross section polishing apparatus, to obtain samples for cross section observation. The cross section of the obtained sample was observed with an electron microscope, and the thickness of the cured film around the hole (through hole) was measured.
[ plating solution resistance ]
The substrate with a cured film obtained by the method described in the above < formation of a cured film > was subjected to electroless GOLD plating treatment according to the standard procedure of electroless GOLD plating solution (trade name: FLASH GOLD 330) manufactured by Okinawa pharmaceutical industry Co. The detailed procedure is as follows.
First, the substrate with the cured film was immersed in a degreasing solution (ICP CLEAN S-135K, manufactured by Aofield pharmaceutical Co., ltd.) at 40℃for 4 minutes, and the substrate with the cured film was degreased. Then, the degreased substrate with the cured film was immersed in an etching solution at 30 ℃ for 1 minute, and the substrate with the cured film was subjected to etching treatment. The etching solution used was an aqueous solution obtained by dissolving sulfuric acid (10 mL/L), sodium persulfate (100 g/L), and copper sulfate pentahydrate (8 g/L) in ion-exchanged water. Then, the cured film-attached substrate after the etching treatment was immersed in a catalyst treatment liquid (30 ℃ C. "ICP ACCERA", pd concentration: 0.04% by weight) for 1 minute, and the cured film-attached substrate was subjected to catalyst treatment. Then, the cured film-attached substrate after the catalyst treatment was immersed in an electroless nickel plating solution (ICP NICORON FPF, manufactured by Okinawa pharmaceutical Co., ltd.) at a temperature of 84℃for 30 minutes, and the cured film-attached substrate was subjected to electroless nickel plating. Then, the substrate with a cured film after electroless nickel plating was immersed in an electroless GOLD plating solution (FLASH GOLD 330, manufactured by Aomu pharmaceutical Co., ltd.) at a temperature of 80℃for 8 minutes, and the substrate with a cured film was subjected to electroless GOLD plating treatment and then washed with water at a temperature of 25 ℃. The washed substrate with the cured film was then heated at 150℃for 30 minutes to obtain a test piece for evaluation of plating solution resistance. The periphery of the circular opening of the cured film formed on the obtained test piece was observed with an optical microscope, and the plating resistance was determined based on the following criteria. When it is determined as a, it is evaluated as "excellent plating resistance". On the other hand, when B or C is determined, it is evaluated as "plating solution resistance is not excellent".
(criterion for determining plating solution resistance)
A: for all the openings (100 openings), impregnation of the cured film and the substrate by the plating solution (impregnation of the plating solution by the openings) was not confirmed.
B: for a part of the openings, impregnation of the cured film and the substrate with the plating solution was confirmed.
C: infiltration of the plating solution between the cured film and the substrate was confirmed for all the openings.
[ discoloration resistance of wiring ]
The test piece evaluated by the method described in the above [ plating solution resistance ] was subjected to hot pressing at 160℃for 60 minutes using a heating and pressurizing device, and then baked at 150℃for 90 minutes using a box-type oven. Next, the wiring of the test piece after baking treatment (specifically, the wiring covered with the cured film) was visually observed, and the discoloration resistance of the wiring was determined by the following criteria. When it is determined as a, it is evaluated as "excellent discoloration resistance of the wiring". On the other hand, when B or C is determined, it is evaluated as "discoloration resistance of the wiring is not excellent".
(criterion for determining discoloration resistance of wiring)
A: no discoloration of the wiring was confirmed at all.
B: discoloration was confirmed in a part of the wiring.
C: discoloration was confirmed in all wirings.
< evaluation result >
The components and the blending amounts of the liquid photosensitive resin compositions used in examples 1 to 14 and comparative examples 1 to 3, the longitudinal width and the lateral width of the substrate used, the thickness of the film-like support used, the thickness of the wiring of the substrate used, the roll diameter of the coating roll used, the physical properties and evaluation results of the liquid photosensitive resin composition used, the evaluation results of the substrate with a coating film, and the evaluation results of the substrate with a cured film are shown in tables 1 to 4. In tables 1 to 4, the numerical values in the columns of the composition of the liquid photosensitive resin composition are the blending amounts (unit: parts by weight) of the components. In tables 1 to 4, the amount of the organic solvent contained in the resin solution SP1, the resin solution SP2, or the resin solution SP3 is also included in the amount of the component (G) (organic solvent). In tables 1 to 4, "-" means that the component was not compounded. In tables 1 to 4, "(C) component" also includes an epoxy compound having only 1 epoxy group. In tables 1 to 4, "(E) component" also includes radical polymerizable compounds having 2 radical polymerizable groups in 1 molecule.
In tables 1 to 4, "369", "828", "1032", "PGE", "DPEHA", "PETA", "321", "8070", "TEGDM" and "2000" are described below, respectively.
369: 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (manufactured by IGM Resins Co., ltd. "Omnirad (registered trademark) 369") as a photo radical polymerization initiator
828:1 epoxy Compound having 2 epoxy groups in the molecule (Mitsubishi Chemical Corporation "jER (registered trademark) 828")
1032:1 epoxy Compound having 3 epoxy groups in the molecule (Mitsubishi Chemical Corporation "jER (registered trademark) 1032H 60")
PGE: phenyl glycidyl ethers
DPEHA: dipentaerythritol hexaacrylate
PETA: pentaerythritol triacrylate
321: EO-modified bisphenol A dimethacrylate (Showa Denko Materials Co., ltd., "Fancryl (registered trademark) FA-321M", average molar number of EO: 10)
8070: crosslinked polyurethane particles (DAIMICBEAZ (registered trademark) UCN-8070CM Clear, average particle diameter: 7 μm)
TEGDM: triethylene glycol dimethyl ether
2000: butadiene-based antifoaming agent (Fullerene AC-2000, co., ltd.)
TABLE 1
TABLE 2
TABLE 3
TABLE 4
In examples 1 to 14, the liquid photosensitive resin composition used contained a binder polymer, a photo radical polymerization initiator, a multifunctional epoxy compound, an epoxy curing accelerator, and a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule.
In examples 1 to 14, the plating solution resistance was determined as a. The flexible printed boards obtained by the production methods of examples 1 to 14 were excellent in plating solution resistance. In examples 1 to 14, the discoloration resistance of the wiring was determined as a. The wiring of the flexible printed circuit board obtained by the production methods of examples 1 to 14 was excellent in discoloration resistance.
In comparative examples 1 to 3, the liquid photosensitive resin composition used did not contain a polyfunctional epoxy compound. In comparative examples 2 and 3, the liquid photosensitive resin composition used did not contain an epoxy curing accelerator. In comparative example 3, the liquid photosensitive resin composition used did not contain a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule.
In comparative examples 1 to 3, the plating resistance was judged as B or C. The plating solution resistance of the flexible printed boards obtained by the manufacturing methods of comparative examples 1 to 3 was not excellent. In comparative examples 1 to 3, the discoloration resistance of the wiring was determined as C. The wiring of the flexible printed circuit board thus obtained by the manufacturing method of comparative examples 1 to 3 was not excellent in discoloration resistance.
As shown by the above results, according to the present invention, a method for manufacturing a flexible printed board excellent in plating solution resistance and discoloration resistance of wiring can be provided.
Description of the reference numerals
11. Substrate board
12a, 12b, 100 applicator roll
13. Film-like support
14. Wiring
15. Hole(s)
17. Liquid photosensitive resin composition

Claims (10)

1. A method for manufacturing a flexible printed board, which comprises applying a liquid photosensitive resin composition to both sides of a substrate using a vertical lift roll coater, wherein the substrate comprises a film-like support and wiring lines provided on both sides of the film-like support,
a hole is provided in the base plate,
the liquid photosensitive resin composition comprises a binder polymer, a photo-radical polymerization initiator, a multifunctional epoxy compound, an epoxy curing accelerator, and a radical polymerizable compound having 3 or more radical polymerizable groups in 1 molecule,
when the liquid photosensitive resin composition is applied, the liquid photosensitive resin composition is applied simultaneously to both sides of the substrate.
2. The method for manufacturing a flexible printed board according to claim 1, wherein the film-like support has a lateral width and a longitudinal width of 200mm or more and 600mm or less.
3. The method for manufacturing a flexible printed board according to claim 1 or 2, wherein the thickness of the film-like support is 8.0 μm or more and 50.0 μm or less.
4. The method for manufacturing a flexible printed board according to any one of claims 1 to 3, wherein a thickness of the wiring is 8 μm or more and 50 μm or less.
5. The method for manufacturing a flexible printed 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.
6. The method for producing a flexible printed board according to any one of claims 1 to 5, wherein the film-like support contains one or more polymers selected from the group consisting of polyimide, polyamide, polyester, polycarbonate, polyarylate, polytetrafluoroethylene, polytrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, perfluoroalkoxy fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, and ethylene-chlorotrifluoroethylene copolymer.
7. The method for producing a flexible printed board according to any one of claims 1 to 6, wherein the binder polymer is one or more polymers selected from the group consisting of a polymer having a urethane bond in 1 molecule, a polymer having an imide group in 1 molecule, a polymer having a (meth) acryloyl group in 1 molecule, and a polymer having a carboxyl group in 1 molecule.
8. The method for manufacturing a flexible printed board according to any one of claims 1 to 7, wherein a content of the epoxy curing accelerator is 0.1 parts by weight or more and 0.5 parts by weight or less with respect to 100 parts by weight of the binder polymer.
9. The method for producing a flexible printed board according to any one of claims 1 to 8, wherein the acid value of the binder polymer is 10mgKOH/g or more.
10. The method for producing a flexible printed board according to any one of claims 1 to 9, wherein the vertical lift roll coater is provided with a pair of coating rolls,
the roll diameter of the coating roll is more than 70mm and less than 150 mm.
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