WO2012042846A1 - Method for forming solder resist - Google Patents

Method for forming solder resist Download PDF

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Publication number
WO2012042846A1
WO2012042846A1 PCT/JP2011/005425 JP2011005425W WO2012042846A1 WO 2012042846 A1 WO2012042846 A1 WO 2012042846A1 JP 2011005425 W JP2011005425 W JP 2011005425W WO 2012042846 A1 WO2012042846 A1 WO 2012042846A1
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WO
WIPO (PCT)
Prior art keywords
curable resin
protective film
resin layer
via hole
solder resist
Prior art date
Application number
PCT/JP2011/005425
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French (fr)
Japanese (ja)
Inventor
遠藤　新
直之 小池
Original Assignee
太陽ホールディングス株式会社
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Application filed by 太陽ホールディングス株式会社 filed Critical 太陽ホールディングス株式会社
Priority to KR1020137003399A priority Critical patent/KR101471794B1/en
Priority to JP2012536202A priority patent/JP5572714B2/en
Publication of WO2012042846A1 publication Critical patent/WO2012042846A1/en

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    • 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
    • H05K3/0011—Working of insulating substrates or insulating layers
    • H05K3/0017—Etching of the substrate by chemical or physical means
    • H05K3/0026—Etching of the substrate by chemical or physical means by laser ablation
    • H05K3/0032—Etching of the substrate by chemical or physical means by laser ablation of organic insulating material
    • H05K3/0035—Etching of the substrate by chemical or physical means by laser ablation of organic insulating material of blind holes, i.e. having a metal layer at the bottom
    • 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
    • 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
    • H05K3/26—Cleaning or polishing of the conductive pattern
    • 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
    • H05K3/288—Removal of non-metallic coatings, e.g. for repairing
    • 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
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/09—Treatments involving charged particles
    • H05K2203/095—Plasma, e.g. for treating a substrate to improve adhesion with a conductor or for cleaning holes
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/13—Moulding and encapsulation; Deposition techniques; Protective layers
    • H05K2203/1377—Protective layers
    • H05K2203/1383—Temporary protective insulating layer
    • 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
    • H05K3/0011—Working of insulating substrates or insulating layers
    • H05K3/0055—After-treatment, e.g. cleaning or desmearing of holes

Definitions

  • the present invention relates to a method for forming a solder resist formed on, for example, a circuit board.
  • solder is prevented from adhering to unnecessary parts, and circuit conductors are exposed to oxidize or humidity.
  • a solder resist is formed in a region excluding the via hole on the circuit board.
  • a photosensitive resin composition is selected as the solder resist, and the via hole / patterning is carried out by developing and peeling off the unexposed portion with an alkaline aqueous solution after exposing and cross-linking the portion other than the via hole forming portion through a mask. I went. At this time, the exposed portion serves as a permanent protective film (solder resist).
  • solder resist an alkaline aqueous solution
  • a curable resin layer serving as a solder resist is formed on a wiring pattern, cured, and then opened by irradiation with a laser beam such as a carbon dioxide laser. It is disclosed.
  • smear which is a residue of the curable resin coating film, remains on the bottom of the via after opening the via hole by laser irradiation. If the smear remains and the process proceeds to the plating process, which is a surface finishing process, unplated plating occurs, resulting in poor solder connection. Therefore, a desmear process for removing smear is required. However, since the vicinity of the via hole is damaged by the laser light irradiation, there is a problem that the surface layer of the solder resist is etched during the desmear process or the opening diameter of the via is increased.
  • Etching (roughening) of the surface layer is preferable if it is an inner layer because it can improve the adhesion to the upper layer, but damage to the solder resist as a permanent protective film in the outer layer decreases reliability. Leads to. Therefore, in order to suppress irradiation damage, it has been proposed to provide a protective film on the curable resin layer and irradiate laser light from the protective film (see, for example, Patent Document 1).
  • This invention is made in view of such a situation, and provides the formation method of the soldering resist which can suppress irradiation of a laser beam and the damage of a desmear process, and can improve reliability. .
  • the method for forming a solder resist of one embodiment of the present invention includes forming a semi-cured curable resin layer having a protective film adhered to a surface on a circuit board, and irradiating a laser beam on the protective film.
  • a feature is that a via hole is formed in a cured curable resin layer, smear in the via hole is removed by a desmear process using plasma, a protective film is peeled off, and a semi-cured curable resin layer is cured. To do.
  • the semi-cured curable resin layer is formed by laminating a dry film of a curable resin on a circuit board, or the curable resin composition on the circuit board. It is preferably formed by coating and drying to form a curable resin layer. With such a configuration, the curable resin layer can be easily formed.
  • the method for forming a solder resist according to one embodiment of the present invention includes curing a curable resin layer formed on a circuit board and having a protective film adhered to the surface, and irradiating the protective film with laser light to be curable.
  • a via hole is formed in the resin layer, smear in the via hole is removed by a desmear process using oxygen plasma, and the protective film is peeled off.
  • solder resist forming method it is preferable to perform ultrasonic cleaning after desmear treatment. With such a configuration, it is possible to suppress residual inorganic components.
  • the solder resist forming method according to one embodiment of the present invention can suppress laser light irradiation and damage of desmear treatment, and can improve reliability.
  • the inventors of the present invention have made extensive studies on the above problems, and as a result, in the formation of the solder resist, a semi-cured curable resin layer having a protective film adhered to the surface is formed on the circuit board, and the protective film is formed.
  • Laser light is irradiated from above to form a via hole in the semi-cured curable resin layer, smear in the via hole is removed by desmear treatment using plasma, the protective film is peeled off, and the semi-cured state is cured
  • the present inventors have found that by curing the curable resin layer, it is possible to suppress damage of laser light irradiation and desmear treatment and improve the reliability of the solder resist, thereby completing the present invention.
  • the laser beam is irradiated to the semi-cured curable resin layer formed on the substrate, the irradiation energy can be suppressed as compared with the cured resin layer, and the laser beam is protected. Since the resin layer is irradiated through the film, irradiation damage near the via hole can be suppressed. Furthermore, by setting the desmear process to a plasma process, the desmear process can be performed without causing damage due to penetration into the interface between the protective film and the curable resin layer during the chemical process. Therefore, the solder resist formed according to the present embodiment can improve the reliability when used as a printed wiring board or the like.
  • FIG. 1 shows a solder resist formation process diagram of the present embodiment.
  • a pretreatment such as degreasing and soft etching is performed on the circuit board 11 in which the conductive layer 11b such as a circuit pattern is formed on the base material 11a.
  • the curable resin dry film 12a is laminated using a vacuum laminator or the like.
  • the dry film is formed on a carrier film, and a cover film is laminated as necessary, and the exposed surface side is adhered to the circuit board with the protective film 13 as any film adhered to the surface.
  • the conditions of laminating there is no particular limitation on the conditions of laminating
  • the temperature 60 ⁇ 140 ° C., vacuum of 20mmHg or less can be carried out at a pressure 1 ⁇ 15kgf / cm 2.
  • a step of smoothing the curable resin layer after lamination by pressing is performed.
  • the smoothing step is performed under normal pressure, and the same conditions as in the laminating step can be used for heating and pressing conditions.
  • the vacuum laminator used in these steps include CVP-300 (manufactured by Nichigo Morton) and MVLP-500 (manufactured by Meiki Seisakusho).
  • the protective film 13 may be laminated after the curable resin composition is applied and dried on the circuit board to form the curable resin layer 12a.
  • the circuit board is not particularly limited, but a multilayer printed wiring such as a single-sided or double-sided printed board provided with a conductive layer such as copper or a build-up board using an insulating core material such as prepreg.
  • a known circuit board such as a board or a flexible printed board is used.
  • thermosetting resin composition As the curable resin composition used for forming the curable resin layer, a thermosetting resin composition, a photocurable resin composition, a photosensitive resin composition, or the like can be used.
  • a thermosetting resin composition containing an epoxy resin, an inorganic filler, and a curing agent is preferably used.
  • epoxy resin examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type.
  • the inorganic filler for example, barium sulfate, calcium sulfate, silica, clay, talc, aluminum hydroxide and the like can be used. These have an absorption peak in the range of wave numbers 900 to 1300 cm ⁇ 1 , which is the wavelength band of a carbon dioxide laser described later, and sublimate or decompose during laser processing, so that residues after laser processing can be suppressed. These can be used alone or in combination of two or more.
  • curing agent examples include imidazoles, AZINE compounds of imidazole, isocyanurate of imidazole, imidazole hydroxymethyl, dicyandiamide and derivatives thereof, melamine and derivatives thereof, diaminomaleonitrile and derivatives thereof, diethylenetriamine, triethylenetetramine, tetra Amines such as ethylenepentamine, bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid dihydrazide, 1,8-diazabicyclo [5,4,0] undecene-7, 3,9-bis (3- Aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, triphenylphosphine, tricyclohexylphosphine, tributylphosphine, methyldiphenylphosphine, etc.
  • Organic phosphine compounds such as are used. These can be used alone or in combination
  • phenoxy resin, polyvinyl acetal resin, polyimide, polyamideimide, etc. may be added alone or in combination of two or more in order to improve the film-forming property of the cured resin and improve the mechanical strength of the cured coating film.
  • a solvent or the like may be contained in order to adjust the concentration and improve the coatability.
  • the protective film 13 is provided in order to suppress laser irradiation damage around the via hole without reaching the curable resin layer.
  • PET polyethylene terephthalate
  • other polyesters such as polyethylene naphthalate, polypropylene (PP), polyethylene (PE), polycarbonate, polymethyl methacrylate (PMMA), cyclic polyolefin, triacetyl.
  • Cellulose, polyether sulfide, polyether ketone, polyimide and the like can be used.
  • the protective film 13 preferably has a thickness of 8-60 ⁇ m. Although the laser workability described later is improved as the thickness is thinner, it is difficult to suppress laser irradiation damage around the via hole when the thickness is less than 8 ⁇ m. On the other hand, when it exceeds 60 ⁇ m, the transmittance of the laser beam is lowered and the aperture diameter is reduced. More preferably, it is 10-50 ⁇ m, and still more preferably 12-38 ⁇ m.
  • a semi-cured curable resin layer is formed on the circuit board by laminating the dry film on the circuit board or by applying the curable resin composition on the circuit board and evaporating and drying it.
  • the semi-cured state refers to a state that is not completely cured, and it is preferable that the curing rate is about 20-80%.
  • the curing rate is less than 20%, fusion or the like is likely to occur at room temperature, and workability is deteriorated.
  • it exceeds 80% the laser processability is deteriorated, the embedding in the circuit during lamination, and the flatness are impaired.
  • the cure rate is 30-75%, more preferably the cure rate is 40-70%.
  • the curing rate is determined by the gelation time (GT1) in the solution of the curable resin composition (before the dry film is produced and before being applied on the circuit board), and on the dry film and the circuit board.
  • GT1 gelation time in the dried state
  • GT1-GT2 gelation time in the dried state
  • the gelation time (curing time) is determined according to 5.7 “curing time test” of JIS C 6521 “Multi-Ply Printed Wiring Board Pre-Preg Test Method”, respectively, curable resin composition solution, dry film, circuit board About 0.3g (solution is 0.3ml) about the state apply
  • laser light such as a carbon dioxide laser
  • an excimer laser or the like
  • a carbon dioxide laser is preferred from the viewpoint of via hole processing speed and cost.
  • a desmear process is performed to remove the smear 15 that is a residue of the curable resin remaining at the bottom of the via hole 14.
  • plasma treatment is used instead of chemical treatment using KMnO 4 or the like.
  • a vacuum plasma apparatus for example, a vacuum plasma apparatus, an atmospheric pressure plasma apparatus, or the like can be used.
  • a known plasma such as a plasma using a reactive gas such as oxygen plasma, a plasma using an inert gas such as argon plasma or helium plasma, or a plasma of a mixed gas thereof may be used. it can.
  • oxygen plasma it is particularly preferable to use oxygen plasma.
  • a highly reactive oxygen plasma used in forming an inner layer via cannot be used because the surface is roughened.
  • the protective film since the protective film is provided, it is possible to more effectively remove smear in the via hole without causing surface roughening.
  • the oxygen plasma treatment in the desmear treatment is also effective when laser irradiation is performed after the curable resin to which the protective film is bonded is cured. In that case, it is preferable to perform a mold release treatment in advance on the protective film.
  • the inorganic component such as filler may not remain sufficiently reactive and may remain, but the inorganic component is removed by ultrasonic cleaning. can do.
  • the protective film 13 is peeled off and heated at 130 to 180 ° C. for 15 to 90 minutes, for example, as shown in FIG. 1 (d).
  • the semi-cured curable resin layer is cured to form the solder resist 12b.
  • a method using a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven, or the like equipped with a heat source of an air heating method using steam, and a method in which hot air in the dryer is brought into countercurrent contact and supported by a nozzle A method of spraying on the body can be used.
  • a solder resist having a via hole is formed on the circuit board.
  • thermosetting resin composition As the curable resin composition, the compositions shown in Table 1 were blended so as to have a blending ratio, premixed with a stirrer, and then kneaded using a three-roll mill to prepare a thermosetting resin composition of the formulation. did.
  • thermosetting resin composition was coated on a 38 ⁇ m-thick PET film (AL-5 Lintec Co., Ltd.) treated with a release agent (alkyd type) using an applicator, and the film thickness after drying was a circuit. It applied uniformly with a reverse coater so that it may become 20 micrometers above.
  • the amount of residual solvent was 1%, and the gelation time at 170 ° C. was 60 seconds.
  • a 400 mm ⁇ 300 mm ⁇ 0.8 mmt double-sided copper clad laminate (MCL-E-679FGR manufactured by Hitachi Chemical Co., Ltd.) on which a conductive layer having a copper thickness of 18 ⁇ m is formed is used as a circuit board, and pretreatment (CZ-8100 + CL A profile corresponding to a copper etching amount of 1 ⁇ m was formed.
  • a dry film from which a polypropylene film has been peeled off is applied to a pre-treated copper clad laminate using a two-chamber vacuum laminator (CVP-300 manufactured by Nichigo Morton) to laminate temperature: 100 ° C., vacuum: 5 mmHg or less, pressure : Laminated under the condition of 5 kg / cm 2 . Furthermore, by press molding at a press temperature of 100 ° C. and a pressure of 5 kg / cm 2 , a curable resin layer (on a circuit) in which a PET film (protective film) is adhered to each surface on both sides of the copper-clad laminate. An evaluation substrate having a thickness of about 20 ⁇ m was obtained.
  • thermosetting resin composition (the gelation time of the solution at 170 ° C. for 120 seconds) was similarly pretreated (CZ-8100 + CL-8300, manufactured by MEC Co., Ltd.) so that the copper etching amount corresponding to 1 ⁇ m of the circuit board was equivalent.
  • CZ-8100 + CL-8300 manufactured by MEC Co., Ltd.
  • the film thickness after drying is 20 ⁇ m on the circuit.
  • Other screen printing methods, die coating methods, and the like may be used.
  • the amount of residual solvent was similarly 1%, and the gelation time at 170 ° C. was 60 seconds.
  • a PET film manufactured by AL-5 Lintec was laminated as a protective film on the surface of the curable resin layer in a semi-cured state by a roll laminator.
  • the above-described two-chamber vacuum laminator may be used, and a flat substrate can be manufactured by a pressing process.
  • a carbon dioxide gas laser (LC-2K2 manufactured by Hitachi Via Mechanics Co., Ltd.) is used to irradiate a laser beam having a wavelength of 9.3 ⁇ m, and the curable resin layer.
  • a via hole was formed. Irradiation conditions were such that the top opening diameter was 65 ⁇ m on the substrate without the protective film, aperture: 1.9 mm, output: 1.5 W, pulse width: 20 ⁇ sec, burst mode: 3 shot.
  • the protective film was peeled off and the same processing was performed.
  • the evaluation substrate was heated at 170 ° C. for 60 minutes in a hot air circulating drying oven (DF610, manufactured by Yamato Kagaku Co., Ltd.) to cure the curable resin layer.
  • DF610 hot air circulating drying oven
  • Plasma treatment 1 Plasma treatment (dry type)
  • the evaluation substrate after forming the via hole was subjected to plasma treatment using a plasma treatment apparatus (AP-1000 March) without peeling off the protective film.
  • the plasma treatment conditions were as follows: plasma gas: oxygen gas, argon gas, degree of vacuum: 200 mtorr, output: 500 W, treatment time: 5 minutes.
  • the protective film was peeled off and the same treatment was performed.
  • ultrasonic cleaning About the evaluation board
  • Table 2 shows the processing contents of each example and comparative example.
  • Comparative Example 1 shows a general inner layer via formation step.
  • Example 1-6 The evaluation substrates of Example 1-6 and Comparative Example 1-6 on which such processing was performed were evaluated as follows.
  • the via hole bottom residue was determined based on the degree of exposure of Cu at the bottom of the via hole, since a brighter image can be obtained with an atom having a larger atomic number in the BEC image.
  • the evaluation results are shown in Table 3. The evaluation criteria are as follows. A: No via hole bottom residue is observed. ⁇ : A slight residue at the bottom of the via hole is observed. ⁇ : A slight residue at the bottom of the via hole is observed. ⁇ : The curable resin is eluted and the penetration of the desmear liquid is severe.
  • FIG. 2 shows a laser processing
  • FIG. 3 shows (a) SEI after desmear treatment + ultrasonic cleaning
  • FIG. 4 shows (a) SEI after laser processing
  • FIG. 5 shows (a) SEI, (b) (a) a partially enlarged image of the ⁇ portion, and (c) BEC image after processing.
  • FIG. 6 shows (a) a BEC image and (b) an optical micrograph after plasma processing after laser processing
  • FIG. 8 shows a BEC image after ultrasonic cleaning
  • FIG. 9 shows (a) a BEC image and (b) an optical micrograph after plasma processing after laser processing
  • FIG. 11 shows a BEC image after ultrasonic cleaning, respectively.
  • the plasma treatment time was the same.
  • the metallic luster is increased by performing ultrasonic cleaning on the plasma-treated material.
  • ultrasonic cleaning can remove residues such as inorganic components remaining in the plasma treatment.
  • Example 1 the optical microscope photograph on the protective film after laser processing in FIG. 12 and after desmearing in FIG. 13 is shown. Moreover, the optical micrograph on the protective film after the desmear of the comparative example 2 is shown in FIG. The state after the laser processing in Comparative Example 2 is the same as that in Example 1.
  • Example 1 damage around the hole was not observed, and the surface layer was in a good state.
  • Comparative Example 2 although the PET film itself used as the protective film has desmear liquid resistance, the protective film is not sufficiently resistant, and thus the protective film is displaced. Further, it can be seen that the chemical solution penetrates into the interface between the protective film and the curable resin layer, so that a large damage is generated around the via hole.
  • FIG. 15 shows an optical micrograph on the protective film after laser processing and FIG. 16 after desmearing. Moreover, the optical microscope photograph on the protective film after the desmear of Example 6 is shown in FIG. In addition, the state after laser processing of Example 4 and Example 6 is the same as that of Example 1, and the state after desmear of Example 4 is the same as FIG.
  • the via hole diameter approaches that obtained by laser processing without providing a protective film.
  • the ultrasonic cleaning may be performed before or after curing of the curable resin layer.
  • FIG. 18 shows an optical micrograph after laser processing and FIG. 19 after desmear treatment with a chemical solution. As shown in these drawings, it is understood that the curable resin layer is completely eluted by performing a desmear treatment with a chemical solution in a semi-cured state.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Non-Metallic Protective Coatings For Printed Circuits (AREA)
  • Production Of Multi-Layered Print Wiring Board (AREA)
  • Laser Beam Processing (AREA)

Abstract

A method for forming a solder resist, said method being capable of increasing reliability by minimizing damage from laser exposure and a desmear process. In said method, a semi-cured curable resin layer with a protective film bonded to the surface thereof is formed on a circuit board; the protective film is exposed to laser light, forming a via hole in the semi-cured curable resin layer; smearing inside the via hole is removed by a desmear process using a plasma; the protective film is detached; and the semi-cured curable resin layer is cured.

Description

ソルダーレジストの形成方法Method for forming solder resist
　本発明は、例えば回路基板上などに形成されるソルダーレジストの形成方法に関する。 The present invention relates to a method for forming a solder resist formed on, for example, a circuit board.
　一般に、電子機器などに用いられるプリント配線板において、プリント配線板に電子部品を実装する際に、不必要な部分にはんだが付着するのを防止すると共に、回路の導体が露出して酸化や湿度により腐食されるのを防ぐために、回路基板上のビアホールを除く領域に、ソルダーレジストが形成されている。 Generally, in printed wiring boards used in electronic devices, when electronic components are mounted on printed wiring boards, solder is prevented from adhering to unnecessary parts, and circuit conductors are exposed to oxidize or humidity. In order to prevent corrosion by soldering, a solder resist is formed in a region excluding the via hole on the circuit board.
　従来ソルダーレジストとしては、感光性樹脂組成物が選択され、ビアホール形成部分以外を、マスクを介して露光し架橋反応させたのち、アルカリ性水溶液などで未露光部分を現像剥離することでビアホール／パターンニングを行ってきた。この際、露光された部分が永久保護膜（ソルダーレジスト）としての役割を果たす。しかしプリント配線板の薄型化／微細配線化／ビアホールの小径化に伴い、感光性樹脂組成物によるパターニングでは十分に対応できないという問題が生じている。そこで、ビアホールの形成方法のひとつとして、配線パターン上にソルダーレジストとなる硬化性樹脂層を形成、硬化させた後、例えば炭酸ガスレーザーなどのレーザー光照射により開口されることにより形成される方法が開示されている。 Conventionally, a photosensitive resin composition is selected as the solder resist, and the via hole / patterning is carried out by developing and peeling off the unexposed portion with an alkaline aqueous solution after exposing and cross-linking the portion other than the via hole forming portion through a mask. I went. At this time, the exposed portion serves as a permanent protective film (solder resist). However, with the thinning of printed wiring boards / miniaturization of wiring / reduction of via holes, patterning with a photosensitive resin composition is not sufficient. Therefore, as one method for forming a via hole, there is a method in which a curable resin layer serving as a solder resist is formed on a wiring pattern, cured, and then opened by irradiation with a laser beam such as a carbon dioxide laser. It is disclosed.
　この工法では、レーザー照射によるビアホール開口後のビア底に硬化性樹脂塗膜の残渣であるスミアが残留する。このスミアが残留したまま、表面の仕上げ工程であるメッキ工程へ進むとめっき未着が生じ、半田接続不良を起こすため、スミアを除去するためのデスミア工程が必要となる。しかしながら、レーザー光照射により、ビアホールの近傍が照射ダメージを受けているため、デスミア処理時にソルダーレジスト表層部がエッチングされたり、ビアの開口径が大きくなるという問題がある。 In this method, smear, which is a residue of the curable resin coating film, remains on the bottom of the via after opening the via hole by laser irradiation. If the smear remains and the process proceeds to the plating process, which is a surface finishing process, unplated plating occurs, resulting in poor solder connection. Therefore, a desmear process for removing smear is required. However, since the vicinity of the via hole is damaged by the laser light irradiation, there is a problem that the surface layer of the solder resist is etched during the desmear process or the opening diameter of the via is increased.
　表層部のエッチング（粗化）は、内層であれば、上層との密着性を向上させることができるため、むしろ好ましいが、外層における永久保護膜としてのソルダーレジストへのダメージは、信頼性の低下につながる。そこで、照射ダメージを抑えるために、硬化性樹脂層上に保護フィルムを設け、その上からレーザー光を照射することが提案されている（例えば特許文献１など参照）。 Etching (roughening) of the surface layer is preferable if it is an inner layer because it can improve the adhesion to the upper layer, but damage to the solder resist as a permanent protective film in the outer layer decreases reliability. Leads to. Therefore, in order to suppress irradiation damage, it has been proposed to provide a protective film on the curable resin layer and irradiate laser light from the protective film (see, for example, Patent Document 1).
特開２０１０－６２４７８号公報JP 2010-62478 A
　このように保護フィルムを設けることにより、レーザー光の照射ダメージは抑えられるものの、その後のデスミア処理の際、ＫＭｎＯ４などの薬液を用いることにより、保護フィルムと硬化塗膜との界面に薬液が浸透し、ダメージを受けてしまうという問題がある。 By providing a protective film in this manner, laser beam irradiation damage can be suppressed, but during subsequent desmear treatment, a chemical solution such as KMnO 4 can be used to penetrate the chemical solution into the interface between the protective film and the cured coating film. However, there is a problem of receiving damage.
　本発明は、このような事情に鑑みてなされたものであり、レーザー光の照射や、デスミア処理のダメージを抑え、信頼性を向上させることが可能なソルダーレジストの形成方法を提供するものである。 This invention is made in view of such a situation, and provides the formation method of the soldering resist which can suppress irradiation of a laser beam and the damage of a desmear process, and can improve reliability. .
　本発明の一態様のソルダーレジストの形成方法は、回路基板上に、表面に保護フィルムが接着された半硬化状態の硬化性樹脂層を形成し、保護フィルム上よりレーザー光を照射して、半硬化状態の硬化性樹脂層にビアホールを形成し、ビアホール内のスミアを、プラズマを用いたデスミア処理により除去し、保護フィルムを剥離し、半硬化状態の硬化性樹脂層を硬化させることを特徴とする。 The method for forming a solder resist of one embodiment of the present invention includes forming a semi-cured curable resin layer having a protective film adhered to a surface on a circuit board, and irradiating a laser beam on the protective film. A feature is that a via hole is formed in a cured curable resin layer, smear in the via hole is removed by a desmear process using plasma, a protective film is peeled off, and a semi-cured curable resin layer is cured. To do.
　このような構成により、レーザー光の照射や、デスミア処理のダメージを抑え、信頼性を向上させることが可能となる。さらに、半硬化状態でレーザー照射を行うため、低エネルギーで所望の径のビアホールを開口させることができるとともに、硬化前に保護フィルムを除去するため、保護フィルムの離型処理を不要とすることができる。 With such a configuration, it is possible to suppress laser light irradiation and desmear processing damage and improve reliability. Furthermore, since laser irradiation is performed in a semi-cured state, a via hole having a desired diameter can be opened with low energy, and the protective film is removed before curing, so that it is not necessary to release the protective film. it can.
　本発明の一態様のソルダーレジストの形成方法において、半硬化状態の硬化性樹脂層は、回路基板上に、硬化性樹脂のドライフィルムを積層する、或いは、前記回路基板上に硬化性樹脂組成物を塗布乾燥して硬化性樹脂層を形成することにより形成されることが好ましい。このような構成により、簡易に硬化性樹脂層を形成することができる。 In the method for forming a solder resist of one embodiment of the present invention, the semi-cured curable resin layer is formed by laminating a dry film of a curable resin on a circuit board, or the curable resin composition on the circuit board. It is preferably formed by coating and drying to form a curable resin layer. With such a configuration, the curable resin layer can be easily formed.
　このようなソルダーレジストの形成方法において、プラズマとして、酸素プラズマを用いることが好ましい。このような構成により、より短時間でスミアの除去を行うことが可能となる。 In such a method for forming a solder resist, it is preferable to use oxygen plasma as the plasma. With such a configuration, it is possible to remove smear in a shorter time.
　本発明の一態様のソルダーレジストの形成方法は、回路基板上に形成され、表面に保護フィルムが接着された硬化性樹脂層を、硬化させ、保護フィルム上よりレーザー光を照射して、硬化性樹脂層にビアホールを形成し、ビアホール内のスミアを、酸素プラズマを用いたデスミア処理により除去し、保護フィルムを剥離することを特徴とする。 The method for forming a solder resist according to one embodiment of the present invention includes curing a curable resin layer formed on a circuit board and having a protective film adhered to the surface, and irradiating the protective film with laser light to be curable. A via hole is formed in the resin layer, smear in the via hole is removed by a desmear process using oxygen plasma, and the protective film is peeled off.
　このような構成により、より短時間でスミアの除去を行うことが可能となるとともに、レーザー光の照射や、デスミア処理のダメージを抑え、信頼性を向上させることが可能となる。 With such a configuration, it is possible to remove smear in a shorter time, and it is possible to improve the reliability by suppressing damage of laser light irradiation and desmear treatment.
　このようなソルダーレジストの形成方法において、デスミア処理後、超音波洗浄を行うことが好ましい。このような構成により、残渣の無機成分の残存を抑制することが可能となる。 In such a solder resist forming method, it is preferable to perform ultrasonic cleaning after desmear treatment. With such a configuration, it is possible to suppress residual inorganic components.
　本発明の一態様のソルダーレジストの形成方法により、レーザー光の照射や、デスミア処理のダメージを抑え、信頼性を向上させることが可能となる。 The solder resist forming method according to one embodiment of the present invention can suppress laser light irradiation and damage of desmear treatment, and can improve reliability.
本発明の一態様のソルダーレジストの形成工程図である。It is a formation process figure of the soldering resist of one mode of the present invention. 本発明の一態様のレーザー加工後のＳＥＩ像及びＢＥＣ像である。It is a SEI image and BEC image after laser processing of one mode of the present invention. 本発明の一態様のデスミア処理＋超音波洗浄後のＳＥＩ像及びＢＥＣ像である。It is the SEI image and BEC image after the desmear process + ultrasonic cleaning of 1 aspect of this invention. 比較例のレーザー加工後のＳＥＩ像及びＢＥＣ像である。It is the SEI image and BEC image after laser processing of a comparative example. 比較例のデスミア処理後のＳＥＩ像及びＢＥＣ像である。It is the SEI image and BEC image after the desmear process of a comparative example. 本発明の一態様のレーザー加工後のＢＥＣ像及び光学顕微鏡写真である。It is the BEC image and optical microscope photograph after the laser processing of 1 aspect of this invention. 本発明の一態様のデスミア処理後のＢＥＣ像及び光学顕微鏡写真である。It is the BEC image and optical microscope photograph after the desmear process of 1 aspect of this invention. 本発明の一態様の超音波洗浄後のＢＥＣ像である。It is a BEC image after ultrasonic cleaning of one mode of the present invention. 本発明の一態様のレーザー加工後のＢＥＣ像及び光学顕微鏡写真である。It is the BEC image and optical microscope photograph after the laser processing of 1 aspect of this invention. 本発明の一態様のデスミア処理後のＢＥＣ像及び光学顕微鏡写真である。It is the BEC image and optical microscope photograph after the desmear process of 1 aspect of this invention. 本発明の一態様の超音波洗浄後のＢＥＣ像である。It is a BEC image after ultrasonic cleaning of one mode of the present invention. 本発明の一態様のレーザー加工後の光学顕微鏡写真である。It is an optical micrograph after laser processing of one mode of the present invention. 本発明の一態様のデスミア処理後の光学顕微鏡写真である。It is an optical microscope photograph after the desmear process of 1 aspect of this invention. 比較例のデスミア処理後の光学顕微鏡写真である。It is an optical microscope photograph after the desmear process of a comparative example. 本発明の一態様のレーザー加工後の光学顕微鏡写真である。It is an optical micrograph after laser processing of one mode of the present invention. 本発明の一態様のデスミア処理後の光学顕微鏡写真である。It is an optical microscope photograph after the desmear process of 1 aspect of this invention. 本発明の一態様のデスミア処理後の光学顕微鏡写真である。It is an optical microscope photograph after the desmear process of 1 aspect of this invention. 比較例のレーザー加工後の光学顕微鏡写真である。It is an optical microscope photograph after laser processing of a comparative example. 比較例のデスミア処理後の光学顕微鏡写真である。It is an optical microscope photograph after the desmear process of a comparative example.
　本発明の発明者らは、上記課題に対し鋭意検討した結果、ソルダーレジストの形成において、回路基板上に、表面に保護フィルムが接着された半硬化状態の硬化性樹脂層を形成し、保護フィルム上よりレーザー光を照射して、半硬化状態の硬化性樹脂層にビアホールを形成し、ビアホール内のスミアを、プラズマを用いたデスミア処理により除去し、保護フィルムを剥離し、半硬化状態の硬化性樹脂層を硬化させることにより、レーザー光の照射や、デスミア処理のダメージを抑え、ソルダーレジストの信頼性を向上させることができることを見出し、本発明を完成するに至った。 The inventors of the present invention have made extensive studies on the above problems, and as a result, in the formation of the solder resist, a semi-cured curable resin layer having a protective film adhered to the surface is formed on the circuit board, and the protective film is formed. Laser light is irradiated from above to form a via hole in the semi-cured curable resin layer, smear in the via hole is removed by desmear treatment using plasma, the protective film is peeled off, and the semi-cured state is cured The present inventors have found that by curing the curable resin layer, it is possible to suppress damage of laser light irradiation and desmear treatment and improve the reliability of the solder resist, thereby completing the present invention.
　上記方法によれば、基板上に形成した半硬化状態の硬化性樹脂層にレーザー光を照射するため、硬化状態の樹脂層よりも照射エネルギーを抑えることができ、また、そのレーザー光は、保護フィルムを介して樹脂層に照射されるため、ビアホール近傍の照射ダメージが抑えられる。さらに、デスミア処理をプラズマ処理とすることにより、薬液処理の際の保護フィルムと硬化性樹脂層との界面への浸透によるダメージを生じることなく、デスミア処理を行うことができる。
　従って、本実施形態により形成されたソルダーレジストにより、プリント配線板などとして用いられる際の信頼性を向上させることが可能となる。 According to the above method, since the laser beam is irradiated to the semi-cured curable resin layer formed on the substrate, the irradiation energy can be suppressed as compared with the cured resin layer, and the laser beam is protected. Since the resin layer is irradiated through the film, irradiation damage near the via hole can be suppressed. Furthermore, by setting the desmear process to a plasma process, the desmear process can be performed without causing damage due to penetration into the interface between the protective film and the curable resin layer during the chemical process.
Therefore, the solder resist formed according to the present embodiment can improve the reliability when used as a printed wiring board or the like.
　以下、本発明の実施の形態について、図面を参照して詳細に説明する。
（実施形態１）
　図１に本実施形態のソルダーレジストの形成工程図を示す。
　図１（ａ）に示すように、基材１１ａ上に回路パターンなどの導電層１１ｂが形成された回路基板１１について、脱脂、ソフトエッチングなどの前処理を行う。そして、硬化性樹脂のドライフィルム１２ａを、真空ラミネーターなどを用いてラミネートする。ドライフィルムは、キャリアフィルム上に形成され、必要に応じてカバーフィルムが積層されたものであり、表面にいずれかのフィルムである保護フィルム１３が接着した状態で、露出面側が回路基板に接着される。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a solder resist formation process diagram of the present embodiment.
As shown in FIG. 1A, a pretreatment such as degreasing and soft etching is performed on the circuit board 11 in which the conductive layer 11b such as a circuit pattern is formed on the base material 11a. Then, the curable resin dry film 12a is laminated using a vacuum laminator or the like. The dry film is formed on a carrier film, and a cover film is laminated as necessary, and the exposed surface side is adhered to the circuit board with the protective film 13 as any film adhered to the surface. The
　ここでラミネートする条件については特に限定されるものではないが、例えば温度６０～１４０℃、真空度２０ｍｍＨｇ以下、圧力１～１５ｋｇｆ／ｃｍ２で行うことができる。さらに好ましくは、ラミネート後の硬化性樹脂層をプレスにより平滑化する工程を行う。平滑化工程は常圧下で行われ、加熱、加圧条件は上記ラミネート工程を同様の条件を用いることができる。これらの工程に用いる真空ラミネーターとしては、例えばＣＶＰ－３００（ニチゴー・モートン社製）やＭＶＬＰ－５００（名機製作所社製）等があげられる。 There is no particular limitation on the conditions of laminating Here, but for example, the temperature 60 ~ 140 ° C., vacuum of 20mmHg or less, can be carried out at a pressure 1 ~ 15kgf / cm 2. More preferably, a step of smoothing the curable resin layer after lamination by pressing is performed. The smoothing step is performed under normal pressure, and the same conditions as in the laminating step can be used for heating and pressing conditions. Examples of the vacuum laminator used in these steps include CVP-300 (manufactured by Nichigo Morton) and MVLP-500 (manufactured by Meiki Seisakusho).
　なお、回路基板上にドライフィルムをラミネートする代わりに、回路基板上に、硬化性樹脂組成物を塗布乾燥し、硬化性樹脂層１２ａを形成した後、保護フィルム１３をラミネートしてもよい。 Instead of laminating the dry film on the circuit board, the protective film 13 may be laminated after the curable resin composition is applied and dried on the circuit board to form the curable resin layer 12a.
　ここで、回路基板としては、特に限定されるものではないが、プリプレグなどの絶縁性のコア材を用い、銅などの導電層が設けられた片面或いは両面プリント基板、ビルドアップ基板など多層プリント配線板や、フレキシブルプリント基板など、公知の回路基板が用いられる。 Here, the circuit board is not particularly limited, but a multilayer printed wiring such as a single-sided or double-sided printed board provided with a conductive layer such as copper or a build-up board using an insulating core material such as prepreg. A known circuit board such as a board or a flexible printed board is used.
　硬化性樹脂層の形成に用いられる硬化性樹脂組成物としては、熱硬化性樹脂組成物、光硬化性樹脂組成物及び感光性樹脂組成物などを用いることができる。例えば、エポキシ樹脂、無機フィラー及び硬化剤を含む熱硬化性樹脂組成物が好適に用いられる。 As the curable resin composition used for forming the curable resin layer, a thermosetting resin composition, a photocurable resin composition, a photosensitive resin composition, or the like can be used. For example, a thermosetting resin composition containing an epoxy resin, an inorganic filler, and a curing agent is preferably used.
　エポキシ樹脂としては、例えば、ビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂、水添ビスフェノールＡ型エポキシ樹脂、臭素化ビスフェノールＡ型エポキシ樹脂、ビスフェノールＳ型エポキシ樹脂、フェノールノボラック型エポキシ樹脂、クレゾールノボラック型エポキシ樹脂、ビスフェノールＡのノボラック型エポキシ樹脂、ビフェニル型エポキシ樹脂、ナフタレン型エポキシ樹脂、ナフトール型エポキシ樹脂、ジシクロペンタジエン型エポキシ樹脂、トリフェニルメタン型エポキシ樹脂、脂環式エポキシ樹脂、脂肪族鎖状エポキシ樹脂、リン含有エポキシ樹脂、アントラセン型エポキシ樹脂、ノルボルネン型エポキシ樹脂、アダマンタン型エポキシ樹脂、フルオレン型エポキシ樹脂などが用いられる。これらは単独で又は２種以上を組合せて使用することができる。 Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type. Epoxy resin, bisphenol A novolak type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, alicyclic epoxy resin, aliphatic chain Epoxy resins, phosphorus-containing epoxy resins, anthracene type epoxy resins, norbornene type epoxy resins, adamantane type epoxy resins, fluorene type epoxy resins, and the like are used. These can be used alone or in combination of two or more.
　無機フィラーとしては、例えば、硫酸バリウム、硫酸カルシウム、シリカ、クレー、タルク、水酸化アルミニウムなどを用いることができる。これらは後述する炭酸ガスレーザーの波長帯である波数９００～１３００ｃｍ-1の範囲内に吸収ピークを持ち、レーザー加工時に昇華又は分解するため、レーザー加工後の残渣を抑制することができる。これらは単独で又は２種以上を組合せて使用することができる。 As the inorganic filler, for example, barium sulfate, calcium sulfate, silica, clay, talc, aluminum hydroxide and the like can be used. These have an absorption peak in the range of wave numbers 900 to 1300 cm −1 , which is the wavelength band of a carbon dioxide laser described later, and sublimate or decompose during laser processing, so that residues after laser processing can be suppressed. These can be used alone or in combination of two or more.
　硬化剤としては、例えば、イミダゾール類、イミダゾールのＡＺＩＮＥ化合物、イミダゾールのイソシアヌル酸塩、イミダゾールヒドロキシメチル体、ジシアンジアミドとその誘導体、メラミンとその誘導体、ジアミノマレオニトリルとその誘導体、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ビス（ヘキサメチレン）トリアミン、トリエタノーアミン、ジアミノジフェニルメタン、有機酸ジヒドラジッドなどのアミン類、１，８－ジアザビシクロ［５，４，０］ウンデセン－７、３，９－ビス（３－アミノプロピル）－２，４，８，１０－テトラオキサスピロ［５，５］ウンデカン、トリフェニルホスフィン、トリシクロヘキシルホスフィン、トリブチルホスフィン、メチルジフェニルホスフィンなどの有機ホスフィン化合物などが用いられる。これらは単独で又は２種以上を組合せて使用することができる。 Examples of the curing agent include imidazoles, AZINE compounds of imidazole, isocyanurate of imidazole, imidazole hydroxymethyl, dicyandiamide and derivatives thereof, melamine and derivatives thereof, diaminomaleonitrile and derivatives thereof, diethylenetriamine, triethylenetetramine, tetra Amines such as ethylenepentamine, bis (hexamethylene) triamine, triethanolamine, diaminodiphenylmethane, organic acid dihydrazide, 1,8-diazabicyclo [5,4,0] undecene-7, 3,9-bis (3- Aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, triphenylphosphine, tricyclohexylphosphine, tributylphosphine, methyldiphenylphosphine, etc. Organic phosphine compounds such as are used. These can be used alone or in combination of two or more.
　その他、硬化樹脂の造膜性を向上させ、硬化塗膜の機械的強度を向上させるために、フェノキシ樹脂、ポリビニルアセタール樹脂、ポリイミド、ポリアミドイミド等を単独で、又は２種類以上を組み合わせて添加したり、濃度を調整し、塗付性を向上させるために、溶剤などを含有してもよい。 In addition, phenoxy resin, polyvinyl acetal resin, polyimide, polyamideimide, etc. may be added alone or in combination of two or more in order to improve the film-forming property of the cured resin and improve the mechanical strength of the cured coating film. In order to adjust the concentration and improve the coatability, a solvent or the like may be contained.
　保護フィルム１３は、ビアホール周辺におけるレーザー照射のダメージを、硬化性樹脂層に到達させることなく抑えるために設けられる。具体的には、ポリエチレンテレフタレート（ＰＥＴ）が好適に用いられ、その他、ポリエチレンナフタレートなどのポリエステル、ポリプロピレン（ＰＰ）、ポリエチレン（ＰＥ）、ポリカーボネート、ポリメタクリル酸メチル（ＰＭＭＡ）、環状ポリオレフィン、トリアセチルセルロース、ポリエーテルサルファイド、ポリエーテルケトン、ポリイミドなどを用いることができる。 The protective film 13 is provided in order to suppress laser irradiation damage around the via hole without reaching the curable resin layer. Specifically, polyethylene terephthalate (PET) is preferably used, and other polyesters such as polyethylene naphthalate, polypropylene (PP), polyethylene (PE), polycarbonate, polymethyl methacrylate (PMMA), cyclic polyolefin, triacetyl. Cellulose, polyether sulfide, polyether ketone, polyimide and the like can be used.
　保護フィルム１３は、その厚さが８－６０μｍであることが好ましい。薄いほど後述するレーザー加工性は向上するが、厚さ８μｍ未満であると、ビアホール周辺のレーザー照射ダメージを抑えることが困難となる。一方、６０μｍを超えると、レーザー光の透過率が低下し、開口径が小さくなる。より好ましくは、１０－５０μｍであり、さらに好ましくは１２－３８μｍである。 The protective film 13 preferably has a thickness of 8-60 μm. Although the laser workability described later is improved as the thickness is thinner, it is difficult to suppress laser irradiation damage around the via hole when the thickness is less than 8 μm. On the other hand, when it exceeds 60 μm, the transmittance of the laser beam is lowered and the aperture diameter is reduced. More preferably, it is 10-50 μm, and still more preferably 12-38 μm.
　このように、ドライフィルムを回路基板上にラミネートする、或いは回路基板上に硬化性樹脂組成物を塗布、揮発乾燥させることにより、回路基板上に半硬化状態の硬化性樹脂層が形成される。 As described above, a semi-cured curable resin layer is formed on the circuit board by laminating the dry film on the circuit board or by applying the curable resin composition on the circuit board and evaporating and drying it.
　半硬化状態とは、完全に硬化していない状態をいい、硬化率が２０－８０％程度であることが好ましい。硬化率が２０％未満であると、室温で融着などが起き易くなり作業性が悪化する。一方８０％を超えると、レーザー加工性の低下、ラミネート時の回路への埋め込み性、平坦性が損なわれる。好ましくは硬化率が３０－７５％であり、より好ましくは、硬化率が４０－７０％である。 The semi-cured state refers to a state that is not completely cured, and it is preferable that the curing rate is about 20-80%. When the curing rate is less than 20%, fusion or the like is likely to occur at room temperature, and workability is deteriorated. On the other hand, if it exceeds 80%, the laser processability is deteriorated, the embedding in the circuit during lamination, and the flatness are impaired. Preferably, the cure rate is 30-75%, more preferably the cure rate is 40-70%.
　ここで、硬化率は、硬化性樹脂組成物の溶液（ドライフィルム作製前、回路基板上に塗布する前の溶液状態）でのゲル化時間（ＧＴ１）と、ドライフィルムおよび回路基板上に塗布・乾燥させた状態でのゲル化時間（ＧＴ２）としたとき、
　　　（ＧＴ１－ＧＴ２）／ＧＴ１×１００
により算出した。 Here, the curing rate is determined by the gelation time (GT1) in the solution of the curable resin composition (before the dry film is produced and before being applied on the circuit board), and on the dry film and the circuit board. When the gelation time in the dried state (GT2),
(GT1-GT2) / GT1 × 100
Calculated by
　ゲル化時間（硬化時間）はＪＩＳ Ｃ ６５２１「多層プリント配線板用 プリプレグ試験方法」の項目５．７「硬化時間試験」に準拠して、それぞれ硬化性樹脂組成物の溶液、ドライフィルム、回路基板上に塗布・乾燥させた状態について、約０．３ｇ（溶液は０．３ｍｌ）サンプリングし、１７０℃の熱盤上にて測定した値とした。 The gelation time (curing time) is determined according to 5.7 “curing time test” of JIS C 6521 “Multi-Ply Printed Wiring Board Pre-Preg Test Method”, respectively, curable resin composition solution, dry film, circuit board About 0.3g (solution is 0.3ml) about the state apply | coated and dried above, it was set as the value measured on the 170 degreeC hotplate.
　そして、図１（ｂ）に示すように、得られた半硬化状態の硬化性樹脂層１２ａの所定位置に、保護フィルム１３を介して、炭酸ガスレーザーなどのレーザー光を照射し、例えばトップ径でφ４０－２００μｍのビアホール１４を形成する。なお、レーザー光としては、炭酸ガスレーザー以外ではＵＶ－ＹＡＧレーザー（第三高調波＝３５５ｎｍ、第四高調波＝２６６ｎｍ）、エキシマレーザーなどを用いることができる。好ましくはビアホールの加工処理速度、コスト面から炭酸ガスレーザーである。 And as shown in FIG.1 (b), laser light, such as a carbon dioxide laser, is irradiated to the predetermined position of the obtained curable resin layer 12a of the semi-hardened state through the protective film 13, for example, top diameter A via hole 14 having a diameter of 40 to 200 μm is formed. As the laser light, a UV-YAG laser (third harmonic = 355 nm, fourth harmonic = 266 nm), an excimer laser, or the like can be used other than the carbon dioxide laser. A carbon dioxide laser is preferred from the viewpoint of via hole processing speed and cost.
　次いで、図１（ｃ）に示すように、ビアホール１４の底に残留した硬化性樹脂の残渣であるスミア１５を除去するためのデスミア処理を行う。このとき、ＫＭｎＯ４などを用いた薬液処理ではなく、プラズマ処理が用いられる。 Next, as shown in FIG. 1C, a desmear process is performed to remove the smear 15 that is a residue of the curable resin remaining at the bottom of the via hole 14. At this time, plasma treatment is used instead of chemical treatment using KMnO 4 or the like.
　このようなプラズマ処理において、例えば、真空プラズマ装置や、常圧プラズマ装置などを用いることができる。そして、プラズマとしては、酸素プラズマなどの反応性のガスを用いたプラズマや、アルゴンプラズマ、ヘリウムプラズマなどの不活性ガスを用いたプラズマ、これらの混合ガスのプラズマなど、公知のプラズマを用いることができる。 In such plasma processing, for example, a vacuum plasma apparatus, an atmospheric pressure plasma apparatus, or the like can be used. As the plasma, a known plasma such as a plasma using a reactive gas such as oxygen plasma, a plasma using an inert gas such as argon plasma or helium plasma, or a plasma of a mixed gas thereof may be used. it can.
　このうち、特に酸素プラズマを用いることが好ましい。通常、ソルダーレジストにおけるビアホール形成の際には、内層ビアの形成の際に用いられる反応性の高い酸素プラズマは、表面が粗化されるため、用いることができない。しかしながら、保護フィルムが設けられているため、表面の粗化を生じることなく、より効果的にビアホール内のスミアを除去することができる。 Of these, it is particularly preferable to use oxygen plasma. Usually, when forming a via hole in a solder resist, a highly reactive oxygen plasma used in forming an inner layer via cannot be used because the surface is roughened. However, since the protective film is provided, it is possible to more effectively remove smear in the via hole without causing surface roughening.
　なお、このようなデスミア処理における酸素プラズマ処理は、保護フィルムが接着された硬化性樹脂を硬化させた後に、レーザー照射を行う際にも有効である。その際、保護フィルムには予め離型処理を施すことが好ましい。 The oxygen plasma treatment in the desmear treatment is also effective when laser irradiation is performed after the curable resin to which the protective film is bonded is cured. In that case, it is preferable to perform a mold release treatment in advance on the protective film.
　このようにしてプラズマによるデスミア処理を行った後、さらに超音波洗浄を行うことが好ましい。プラズマ処理により、有機成分は除去されるものの、フィラーなどの無機成分に対しては、十分な反応性が得られず、残存する恐れがあるが、超音波洗浄を行うことにより、無機成分を除去することができる。 It is preferable to further perform ultrasonic cleaning after the desmear treatment with plasma in this way. Although the organic component is removed by the plasma treatment, the inorganic component such as filler may not remain sufficiently reactive and may remain, but the inorganic component is removed by ultrasonic cleaning. can do.
　このようにして、デスミア処理、必要に応じて超音波洗浄を行った後、保護フィルム１３を剥離し、図１（ｄ）に示すように、例えば１３０～１８０℃で１５～９０分間加熱することにより、半硬化状態の硬化性樹脂層を硬化させ、ソルダーレジスト１２ｂを形成する。 In this way, after the desmear treatment and ultrasonic cleaning as necessary, the protective film 13 is peeled off and heated at 130 to 180 ° C. for 15 to 90 minutes, for example, as shown in FIG. 1 (d). Thus, the semi-cured curable resin layer is cured to form the solder resist 12b.
　硬化方法としては、熱風循環式乾燥炉、ＩＲ炉、ホットプレート、コンベクションオーブンなど、蒸気による空気加熱方式の熱源を備えたものを用い、乾燥機内の熱風を向流接触させる方法、およびノズルより支持体に吹き付ける方法を用いることができる。
　このようにして、回路基板上にビアホールを有するソルダーレジストが形成される。 As a curing method, a method using a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven, or the like equipped with a heat source of an air heating method using steam, and a method in which hot air in the dryer is brought into countercurrent contact and supported by a nozzle A method of spraying on the body can be used.
Thus, a solder resist having a via hole is formed on the circuit board.
　以下に実施例及び比較例を示して具体的に説明するが、本発明は、これら実施例に限定されるものではない。尚、以下において「部」及び「％」とあるのは、特に断りのない限り全て質量基準である。 Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following, “parts” and “%” are based on mass unless otherwise specified.
（硬化性樹脂組成物の調製）
　硬化性樹脂組成物として、表１に示す組成、配合比となるように配合し、攪拌機にて予備混合した後、３本ロールミルを用いて混練して、処方の熱硬化性樹脂組成物を調製した。
Figure JPOXMLDOC01-appb-T000001
 ＊１：エポキシ当量１８４－１９４ Ｂｉｓ－Ａ型液状エポキシ樹脂（三菱化学社製）
＊２：エポキシ当量１３５－１６５ ナフトール型エポキシ樹脂（ＤＩＣ社製）
＊３：エポキシ当量２００－２３０ クレゾールノボラック型エポキシ樹脂（ＤＩＣ社製）の固形分６０％シクロヘキサノン溶液
＊４：フェノキシ樹脂（三菱化学社製）の固形分３０％のシクロヘキサノン溶液
＊５：エポキシ当量１０５ フェノールノボラック型エポキシ樹脂（エポキシ：ＯＨ≒１：０．５）（住友ベークライト社製）の固形分６０％シクロヘキサノン溶液
＊６：球状シリカ（アドマテックス社製）
＊７：硫酸バリウム（堺化学社製）
＊８：イミダゾール（四国化成社製）
＊９：溶剤 (Preparation of curable resin composition)
As the curable resin composition, the compositions shown in Table 1 were blended so as to have a blending ratio, premixed with a stirrer, and then kneaded using a three-roll mill to prepare a thermosetting resin composition of the formulation. did.
Figure JPOXMLDOC01-appb-T000001
 * 1: Epoxy equivalent 184-194 Bis-A liquid epoxy resin (Mitsubishi Chemical Corporation)
* 2: Epoxy equivalent 135-165 naphthol type epoxy resin (manufactured by DIC)
* 3: Epoxy equivalent 200-230 Cyclohexanone solution with a solid content of cresol novolac type epoxy resin (manufactured by DIC) 60% * 4: Cyclohexanone solution with a solid content of phenoxy resin (manufactured by Mitsubishi Chemical Corporation) * 5: Epoxy equivalent 105 Phenol novolac type epoxy resin (epoxy: OH≈1: 0.5) (Sumitomo Bakelite Co., Ltd.) solid content 60% cyclohexanone solution * 6: spherical silica (manufactured by Admatechs)
* 7: Barium sulfate (manufactured by Sakai Chemical Co., Ltd.)
* 8: Imidazole (manufactured by Shikoku Chemicals)
* 9: Solvent
（評価基板の作製１：回路基板＋ドライフィルム）
　得られた熱硬化性樹脂組成物を、離型剤（アルキッド系）で処理された厚さ３８μｍのＰＥＴフィルム（ＡＬ－５ リンテック社製）上に、アプリケーターを用いて、乾燥後膜厚が回路上で２０μｍとなるように、リバースコーターにより均一に塗布した。 (Production of evaluation board 1: circuit board + dry film)
The obtained thermosetting resin composition was coated on a 38 μm-thick PET film (AL-5 Lintec Co., Ltd.) treated with a release agent (alkyd type) using an applicator, and the film thickness after drying was a circuit. It applied uniformly with a reverse coater so that it may become 20 micrometers above.
　そして、設定温度が１１５℃の乾燥炉にて、５分間乾燥させ、半硬化状態の硬化性樹脂層を形成した。得られた硬化性樹脂層において、残留溶剤量は１％で、１７０℃でのゲル化時間は６０秒であった。 Then, it was dried for 5 minutes in a drying furnace having a set temperature of 115 ° C. to form a semi-cured curable resin layer. In the obtained curable resin layer, the amount of residual solvent was 1%, and the gelation time at 170 ° C. was 60 seconds.
　次いで、厚さ１５μｍのポリプロピレンフィルムを張り合わせながら、ロール状に巻き取った。さらに、幅４００ｍｍのスリット加工を行い、３層構造のドライフィルムを作製した。 Next, it was wound up into a roll while laminating a polypropylene film having a thickness of 15 μm. Furthermore, slit processing with a width of 400 mm was performed to produce a dry film having a three-layer structure.
　そして、回路基板として、銅厚１８μｍの導電層が形成された４００ｍｍ×３００ｍｍ×０．８ｍｍｔの両面銅張積層板（ＭＣＬ－Ｅ－６７９ＦＧＲ 日立化成工業社製）を用い、前処理（ＣＺ－８１００＋ＣＬ－８３００ ＭＥＣ社製）により、銅エッチング量１μｍ相当のプロファイルを形成した。 Then, a 400 mm × 300 mm × 0.8 mmt double-sided copper clad laminate (MCL-E-679FGR manufactured by Hitachi Chemical Co., Ltd.) on which a conductive layer having a copper thickness of 18 μm is formed is used as a circuit board, and pretreatment (CZ-8100 + CL A profile corresponding to a copper etching amount of 1 μm was formed.
　前処理の施された銅張積層板に、ポリプロピレンフィルムを剥離したドライフィルムを、２チャンバー式真空ラミネーター（ＣＶＰ－３００ ニチゴーモートン社製）により、ラミネート温度：１００℃、真空度：５ｍｍＨｇ以下、圧力：５ｋｇ／ｃｍ２の条件でラミネートした。さらに、プレス温度：１００℃、圧力：５ｋｇ／ｃｍ２でプレス成型することにより、銅張積層板の両面に、それぞれ表面にＰＥＴフィルム（保護フィルム）が接着された硬化性樹脂層（回路上で約２０μｍ厚）が形成された評価基板を得た。 A dry film from which a polypropylene film has been peeled off is applied to a pre-treated copper clad laminate using a two-chamber vacuum laminator (CVP-300 manufactured by Nichigo Morton) to laminate temperature: 100 ° C., vacuum: 5 mmHg or less, pressure : Laminated under the condition of 5 kg / cm 2 . Furthermore, by press molding at a press temperature of 100 ° C. and a pressure of 5 kg / cm 2 , a curable resin layer (on a circuit) in which a PET film (protective film) is adhered to each surface on both sides of the copper-clad laminate. An evaluation substrate having a thickness of about 20 μm was obtained.
（評価基板の作製２：回路基板上に塗工＋保護フィルム）
　得られた熱硬化性樹脂組成物（溶液の１７０℃でのゲル化時間１２０秒）を、同様に前処理（ＣＺ－８１００＋ＣＬ－８３００ ＭＥＣ社製）により、回路基板である銅エッチング量１μｍ相当のプロファイルが形成された銅厚１８μｍの４００ｍｍ×３００ｍｍ×０．８ｍｍｔの両面銅張積層板（ＭＣＬ－Ｅ－６７９ＦＧＲ 日立化成工業社製）上に、乾燥後膜厚が回路上で２０μｍとなるように、ロールコーター（ファーネス社製）を用いて均一に塗布した。なお、その他スクリーン印刷法、ダイコート法などを用いて塗布してもよい。 (Production of evaluation board 2: coating on circuit board + protective film)
The obtained thermosetting resin composition (the gelation time of the solution at 170 ° C. for 120 seconds) was similarly pretreated (CZ-8100 + CL-8300, manufactured by MEC Co., Ltd.) so that the copper etching amount corresponding to 1 μm of the circuit board was equivalent. On a double-sided copper-clad laminate (MCL-E-679FGR manufactured by Hitachi Chemical Co., Ltd.) of 400 mm × 300 mm × 0.8 mmt with a copper thickness of 18 μm on which the profile is formed, the film thickness after drying is 20 μm on the circuit Then, it was uniformly applied using a roll coater (Furness). Other screen printing methods, die coating methods, and the like may be used.
　そして、設定温度が１１５℃の乾燥炉にて、５分間乾燥させ、半硬化状態の硬化性樹脂層を形成した。得られた硬化性樹脂層において、同様に残留溶剤量は１％で、１７０℃でのゲル化時間は６０秒であった。 Then, it was dried for 5 minutes in a drying furnace having a set temperature of 115 ° C. to form a semi-cured curable resin layer. In the obtained curable resin layer, the amount of residual solvent was similarly 1%, and the gelation time at 170 ° C. was 60 seconds.
　次いで、半硬化状態の硬化性樹脂層表面に、ロールラミネーターにより、保護フィルムとしてＰＥＴフィルム（ＡＬ－５ リンテック社製）をラミネートした。このとき、上述の２チャンバー式真空ラミネーターを用いてもよく、プレス工程によりフラットな基板の作製を行うことができる。 Next, a PET film (manufactured by AL-5 Lintec) was laminated as a protective film on the surface of the curable resin layer in a semi-cured state by a roll laminator. At this time, the above-described two-chamber vacuum laminator may be used, and a flat substrate can be manufactured by a pressing process.
（硬化性樹脂層のレーザー加工（ビアホール形成））
　保護フィルム（ＰＥＴフィルム）を剥離することなく、保護フィルム上より、炭酸ガスレーザー（ＬＣ－２Ｋ２ 日立ビアメカニクス社製）を用いて、波長９．３μｍのレーザー光を照射して、硬化性樹脂層にビアホールを形成した。照射条件は、保護フィルムなしの状態の基板でトップの開口径が６５μｍとなる条件とし、アパチャー：１．９ｍｍ、出力：１．５Ｗ、パルス幅：２０μｓｅｃ、バーストモード：３ｓｈｏｔとした。
　比較例として、保護膜を剥離して同様の加工を行った。 (Laser processing of curable resin layer (via hole formation))
Without peeling off the protective film (PET film), a carbon dioxide gas laser (LC-2K2 manufactured by Hitachi Via Mechanics Co., Ltd.) is used to irradiate a laser beam having a wavelength of 9.3 μm, and the curable resin layer. A via hole was formed. Irradiation conditions were such that the top opening diameter was 65 μm on the substrate without the protective film, aperture: 1.9 mm, output: 1.5 W, pulse width: 20 μsec, burst mode: 3 shot.
As a comparative example, the protective film was peeled off and the same processing was performed.
（硬化性樹脂層の硬化）
　レーザー加工（ビアホール形成）の前又はデスミア後に、評価基板を熱風循環式乾燥炉（ＤＦ６１０ ヤマト科学社製）において、１７０℃で６０分間加熱し、硬化性樹脂層を硬化させた。 (Curing of curable resin layer)
Before laser processing (via hole formation) or after desmearing, the evaluation substrate was heated at 170 ° C. for 60 minutes in a hot air circulating drying oven (DF610, manufactured by Yamato Kagaku Co., Ltd.) to cure the curable resin layer.
（デスミア処理１：プラズマ処理（乾式））
　ビアホール形成後の評価基板について、保護フィルムを剥離することなく、プラズマ処理装置（ＡＰ－１０００ マーチ社製）を用いて、プラズマ処理を行った。プラズマ処理条件は、プラズマガス：酸素ガス、アルゴンガス、真空度：２００ｍｔｏｒｒ、出力：５００Ｗ、処理時間：５分とした。
　比較例として、保護フィルムを剥離して同様の処理を行った。 (Desmear treatment 1: Plasma treatment (dry type))
The evaluation substrate after forming the via hole was subjected to plasma treatment using a plasma treatment apparatus (AP-1000 March) without peeling off the protective film. The plasma treatment conditions were as follows: plasma gas: oxygen gas, argon gas, degree of vacuum: 200 mtorr, output: 500 W, treatment time: 5 minutes.
As a comparative example, the protective film was peeled off and the same treatment was performed.
（デスミア処理２：ＫＭｎＯ４処理（湿式））
　比較例として、ビアホール形成後の評価基板について、保護フィルムを設けたものと剥離したものについて、ＫＭｎＯ４水溶液（ローム＆ハース社製）を用いて薬液処理を行った。処理条件は、膨潤（薬液：ＭＬＢ－２１１、８０℃／１０分）→粗化（薬液：ＭＬＢ－２１３，８０℃／１５分）→還元（ＭＬＢ－２１６、５０℃／５分）とした。 (Desmear treatment 2: KMnO 4 treatment (wet))
As a comparative example, the evaluation substrate after forming via holes, for those stripping and that a protective film was subjected to chemical treatment with KMnO 4 aqueous solution (Rohm & Haas). The treatment conditions were swelling (chemical solution: MLB-211, 80 ° C./10 minutes) → roughening (chemical solution: MLB-213, 80 ° C./15 minutes) → reduction (MLB-216, 50 ° C./5 minutes).
（超音波洗浄）
　デスミア処理後の評価基板について、超音波洗浄ライン（ＩＵＳ２４ 石井表記社製）を用いて、速度１．６ｍ／ｍｉｎ、出力約８００Ｗの条件で超音波洗浄を行った。 (Ultrasonic cleaning)
About the evaluation board | substrate after a desmear process, ultrasonic cleaning was performed on the conditions of speed 1.6m / min and output about 800W using the ultrasonic cleaning line (IUS24 Ishii notation company make).
　表２に、各実施例、比較例の処理内容を示す。なお、比較例１は、一般的な内層ビア形成工程を示している。 Table 2 shows the processing contents of each example and comparative example. Comparative Example 1 shows a general inner layer via formation step.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　このような処理が行われた実施例１－６、比較例１－６の評価基板について、以下のように評価を行った。 The evaluation substrates of Example 1-6 and Comparative Example 1-6 on which such processing was performed were evaluated as follows.
（走査型電子顕微鏡による観察）
　評価基板の表面状態、ビアホール内の状態を、走査型電子顕微鏡（ＳＥＭ：ＪＳＭ－６６１０Ｖ 日本電子社製）により観察し、ＳＥＩ（二次電子像）により、ビアホールの形状の確認を行うとともに、表層部のダメージの有無を評価した。評価結果を表３に示す。なお、評価基準は以下の通りである。
　○：表層部のダメージが認められない。
　×：表層部がダメージを受けている。
　××：ビアホール周辺部に顕著なダメージを受けている。 (Observation with a scanning electron microscope)
The surface state of the evaluation substrate and the state in the via hole are observed with a scanning electron microscope (SEM: JSM-6610V manufactured by JEOL Ltd.), and the shape of the via hole is confirmed by SEI (secondary electron image). The presence or absence of damage was evaluated. The evaluation results are shown in Table 3. The evaluation criteria are as follows.
○: Damage to the surface layer is not recognized.
X: The surface layer is damaged.
XX: Significant damage is received around the via hole.
　また、ＢＥＣ像（反射電子像）により、ビアホール底残渣の有無を評価した。なお、ビアホール底残渣は、ＢＥＣ像において、原子番号の大きな原子ほど光沢のある画像を得ることができることから、ビアホール底のＣｕの露出程度により判断した。評価結果を表３に示す。なお、評価基準は以下の通りである。
　◎：ビアホール底残渣が認められない。
　○：ビアホール底残渣がわずかに認められる。
　△：ビアホール底残渣が少し認められる。
　×：硬化性樹脂が溶出し、デスミア液の浸透も激しい In addition, the presence or absence of via hole bottom residue was evaluated by a BEC image (reflected electron image). The via hole bottom residue was determined based on the degree of exposure of Cu at the bottom of the via hole, since a brighter image can be obtained with an atom having a larger atomic number in the BEC image. The evaluation results are shown in Table 3. The evaluation criteria are as follows.
A: No via hole bottom residue is observed.
○: A slight residue at the bottom of the via hole is observed.
Δ: A slight residue at the bottom of the via hole is observed.
×: The curable resin is eluted and the penetration of the desmear liquid is severe.
（光学顕微鏡による観察）
　評価基板の表面状態を、光学顕微鏡（ＥＣＬＩＰＳＥ ＬＶ－１００ ニコン社製）により観察し、ビアホールの形状と、ビアホール周辺部のダメージの有無を評価するとともに、レーザー加工後と、デスミア後のビアホールのトップ径を測長した。そして、トップ径のレーザー加工後とデスミア後の値を比較し、変化の有無により、ビアホールの形状を評価した。評価結果を表３に示す。 (Observation with an optical microscope)
The surface state of the evaluation substrate is observed with an optical microscope (ECLIPSE LV-100, manufactured by Nikon) to evaluate the shape of the via hole and the presence or absence of damage around the via hole, and the top of the via hole after laser processing and after desmearing The diameter was measured. Then, the values of the top diameter after laser processing and after desmear were compared, and the shape of the via hole was evaluated based on the presence or absence of the change. The evaluation results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　実施例１について、図２にレーザー加工後の、図３にデスミア処理＋超音波洗浄後の（ａ）ＳＥＩ、（ｂ）(ａ)の□部の部分拡大像、（ｃ）ＢＥＣ像をそれぞれ示す。また、比較例２について、図４にレーザー加工後の、図５にデスミア処理後の（ａ）ＳＥＩ、（ｂ）(ａ)の□部の部分拡大像、（ｃ）ＢＥＣ像をそれぞれ示す。 For Example 1, FIG. 2 shows a laser processing, FIG. 3 shows (a) SEI after desmear treatment + ultrasonic cleaning, (b) a partially enlarged image of the □ part of (a), and (c) a BEC image. Show. Further, for Comparative Example 2, FIG. 4 shows (a) SEI after laser processing, and FIG. 5 shows (a) SEI, (b) (a) a partially enlarged image of the □ portion, and (c) BEC image after processing.
　図２－４に示すように、ＫＭｎＯ４によるデスミア処理を行ったものは、ビアホール周辺に大きなダメージが認められ、表面も荒れている。さらに、ビアホール径が大きくなっている。一方、酸素プラズマによるデスミア処理を行ったものは、ビアホール周辺のダメージが認められず、ビアホール径も変わっていない。 As shown in FIG. 2-4, when the desmear treatment with KMnO 4 is performed, a large damage is recognized around the via hole, and the surface is rough. Further, the via hole diameter is increased. On the other hand, in the case of desmear treatment with oxygen plasma, damage around the via hole is not recognized, and the diameter of the via hole is not changed.
　さらに、実施例１について、図６にレーザー加工後の、図７にプラズマ処理後の（ａ）ＢＥＣ像、（ｂ）光学顕微鏡写真を、図８に超音波洗浄後のＢＥＣ像をそれぞれ示す。また、比較例５について、図９にレーザー加工後の、図１０にプラズマ処理後の（ａ）ＢＥＣ像、（ｂ）光学顕微鏡写真を、図１１に超音波洗浄後のＢＥＣ像をそれぞれ示す。なお、プラズマ処理時間は同じとした。 Further, with respect to Example 1, FIG. 6 shows (a) a BEC image and (b) an optical micrograph after plasma processing after laser processing, and FIG. 8 shows a BEC image after ultrasonic cleaning, respectively. For Comparative Example 5, FIG. 9 shows (a) a BEC image and (b) an optical micrograph after plasma processing after laser processing, and FIG. 11 shows a BEC image after ultrasonic cleaning, respectively. The plasma treatment time was the same.
　図６－１１に示すように、いずれもプラズマ処理後のビアホール径の拡大は認められないものの、アルゴンプラズマ処理をおこなったものについては、光学顕微鏡写真においては金属光沢が認められるものの、ＢＥＣ像において、金属光沢（Ｃｕ）が認められず、酸素プラズマ処理と同じ処理時間では、スミアが残ることがわかる。このように、酸素プラズマを用いることにより、効率的にデスミア処理を行うことができる。 As shown in FIGS. 6-11, no increase in the diameter of the via hole after the plasma treatment was observed, but the metal plasma was observed in the optical micrograph for the one subjected to the argon plasma treatment, but in the BEC image It can be seen that no metallic luster (Cu) is observed and smear remains in the same treatment time as the oxygen plasma treatment. Thus, desmear treatment can be efficiently performed by using oxygen plasma.
　また、プラズマ処理を行ったものについて、さらに超音波洗浄を行うことにより、より金属光沢が増加している。このように、超音波洗浄により、プラズマ処理で残った無機分などの残渣を除去できることがわかる。 In addition, the metallic luster is increased by performing ultrasonic cleaning on the plasma-treated material. Thus, it can be seen that ultrasonic cleaning can remove residues such as inorganic components remaining in the plasma treatment.
　また、実施例１について、図１２にレーザー加工後、図１３にデスミア後の保護フィルム上の光学顕微鏡写真を示す。また、図１４に比較例２のデスミア後の保護フィルム上の光学顕微鏡写真を示す。なお、比較例２のレーザー加工後の状態は、実施例１と同様である。 Moreover, about Example 1, the optical microscope photograph on the protective film after laser processing in FIG. 12 and after desmearing in FIG. 13 is shown. Moreover, the optical micrograph on the protective film after the desmear of the comparative example 2 is shown in FIG. The state after the laser processing in Comparative Example 2 is the same as that in Example 1.
　図１２－１４に示すように、実施例１においては、穴周辺部のダメージは認められず、表層は良好な状態である。一方、比較例２においては、保護フィルムとしたＰＥＴフィルム自体にはデスミア液耐性があるものの、水圧に対する耐性が十分でないため、保護フィルムにズレが生じている。また、保護フィルムと硬化性樹脂層との界面に、薬液が浸透するため、ビアホール周辺に大きなダメージが生じていることがわかる。 As shown in FIGS. 12-14, in Example 1, damage around the hole was not observed, and the surface layer was in a good state. On the other hand, in Comparative Example 2, although the PET film itself used as the protective film has desmear liquid resistance, the protective film is not sufficiently resistant, and thus the protective film is displaced. Further, it can be seen that the chemical solution penetrates into the interface between the protective film and the curable resin layer, so that a large damage is generated around the via hole.
　さらに、実施例３について、図１５にレーザー加工後、図１６にデスミア後の保護フィルム上の光学顕微鏡写真を示す。また、図１７に実施例６のデスミア後の保護フィルム上の光学顕微鏡写真を示す。なお、実施例４、実施例６のレーザー加工後の状態は、実施例１と同様であり、実施例４のデスミア後の状態は図３と同様である Further, for Example 3, FIG. 15 shows an optical micrograph on the protective film after laser processing and FIG. 16 after desmearing. Moreover, the optical microscope photograph on the protective film after the desmear of Example 6 is shown in FIG. In addition, the state after laser processing of Example 4 and Example 6 is the same as that of Example 1, and the state after desmear of Example 4 is the same as FIG.
　図１５－１７に示すように、未硬化状態の硬化性樹脂層をレーザー加工するものであるため、ビアホール径は、保護フィルムを設けないでレーザー加工したものに近づく。また、わずかに、ビアホール周辺にダメージが認められるものの、比較例２と比べるとはるかに良好な状態が得られていることがわかる。また、図１６と図１７に有意差は認められないことから、超音波洗浄は、硬化性樹脂層の硬化の前でも後でもよいことがわかる。 As shown in FIGS. 15-17, since the curable resin layer in an uncured state is processed by laser, the via hole diameter approaches that obtained by laser processing without providing a protective film. In addition, although a slight damage is observed around the via hole, it can be seen that a much better state is obtained as compared with Comparative Example 2. Moreover, since there is no significant difference between FIG. 16 and FIG. 17, it can be seen that the ultrasonic cleaning may be performed before or after curing of the curable resin layer.
　なお、比較例３について、図１８にレーザー加工後、図１９に薬液によるデスミア処理後の、光学顕微鏡写真を示す。これらの図に示すように、半硬化状態で薬液によるデスミア処理を行うことにより、硬化性樹脂層が全て溶出してしまうことがわかる。 For Comparative Example 3, FIG. 18 shows an optical micrograph after laser processing and FIG. 19 after desmear treatment with a chemical solution. As shown in these drawings, it is understood that the curable resin layer is completely eluted by performing a desmear treatment with a chemical solution in a semi-cured state.
　１１…回路基板
　１１ａ…基材
　１１ｂ…導電層
　１２ａ…硬化性樹脂層
　１２ｂ…ソルダーレジスト
　１３…保護フィルム
　１４…ビアホール
　１５…スミア DESCRIPTION OF SYMBOLS 11 ... Circuit board 11a ... Base material 11b ... Conductive layer 12a ... Curable resin layer 12b ... Solder resist 13 ... Protective film 14 ... Via hole 15 ... Smear

Claims (5)

  1. 　回路基板上に、表面に保護フィルムが接着された半硬化状態の硬化性樹脂層を形成し、
    　前記保護フィルム上よりレーザー光を照射して、前記半硬化状態の硬化性樹脂層にビアホールを形成し、
    　前記ビアホール内のスミアを、プラズマを用いたデスミア処理により除去し、
    　前記保護フィルムを剥離し、
    　前記半硬化状態の硬化性樹脂層を硬化させることを特徴とするソルダーレジストの形成方法。     On the circuit board, a semi-cured curable resin layer with a protective film adhered to the surface is formed,
    Irradiate laser light on the protective film to form a via hole in the semi-cured curable resin layer,
    Smear in the via hole is removed by a desmear process using plasma,
    Peeling off the protective film,
    A method for forming a solder resist, comprising curing the semi-cured curable resin layer.
  2. 　前記半硬化状態の硬化性樹脂層は、回路基板上に、硬化性樹脂のドライフィルムを積層する、或いは、前記回路基板上に硬化性樹脂組成物を塗布乾燥して前記硬化性樹脂層を形成することにより形成されることを特徴とする請求項1に記載のソルダーレジストの形成方法。 The semi-cured curable resin layer is formed by laminating a dry film of a curable resin on a circuit board, or by applying and drying a curable resin composition on the circuit board to form the curable resin layer. 2. The method for forming a solder resist according to claim 1, wherein the solder resist is formed.
  3. 　前記プラズマは、酸素プラズマであることを特徴とする請求項１又は請求項２に記載のソルダーレジストの形成方法。 3. The method of forming a solder resist according to claim 1, wherein the plasma is oxygen plasma.
  4. 　回路基板上に形成され、表面に保護フィルムが接着された硬化性樹脂層を、硬化させ、
    　前記保護フィルム上よりレーザー光を照射して、前記硬化性樹脂層にビアホールを形成し、
    　前記ビアホール内のスミアを、酸素プラズマを用いたデスミア処理により除去し、
    　前記保護フィルムを剥離することを特徴とするソルダーレジストの形成方法。     A curable resin layer formed on a circuit board and having a protective film adhered to the surface is cured,
    Irradiate laser light on the protective film to form a via hole in the curable resin layer,
    Smear in the via hole is removed by desmear treatment using oxygen plasma,
    A method for forming a solder resist, comprising peeling off the protective film.
  5. 　前記デスミア処理後、超音波洗浄を行うことを特徴とする請求項１から請求項４のいずれか１項に記載のソルダーレジストの形成方法。 The method for forming a solder resist according to any one of claims 1 to 4, wherein ultrasonic cleaning is performed after the desmear treatment.
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JP5572714B2 (en) 2014-08-13
KR20130027048A (en) 2013-03-14

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