JP2014074764A - Photosensitive element, method for forming resist pattern using the same, and method for manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive element having a support film, in which flaws generating in the support film can be sufficiently suppressed, and to provide a method for forming a resist pattern and a method for manufacturing a printed wiring board using the photosensitive element.SOLUTION: The photosensitive element includes a support film 10 and a layer 20 made of a photosensitive resin composition formed on the support film 10; and the photosensitive element further includes a self-healing layer or a hard coat layer on a surface of the supporting film 10 not in contact with the layer 20 made of the photosensitive resin composition. The layer made of the photosensitive resin composition comprises (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator.

Description

  The present invention relates to a photosensitive element, a resist pattern forming method using the same, and a printed wiring board manufacturing method.

  Conventionally, as a resist material used for etching and plating in the field of printed wiring board manufacturing and metal precision processing, a support film, a layer made of a photosensitive resin composition (hereinafter referred to as “photosensitive layer”) and protection are used. Photosensitive elements composed of films are widely used.

  A printed wiring board is manufactured as follows, for example. First, after peeling off the protective film of the photosensitive element from the photosensitive layer, the photosensitive layer is laminated on the conductive film of the substrate. Next, after pattern exposure is performed on the photosensitive layer, an unexposed portion is removed with a developing solution to form a resist pattern. And a printed wiring board is formed by patterning a conductive film based on this resist pattern.

For the support film used in the photosensitive element, a support film having a surface resistivity of 10 ¹³ Ω or less or a formed resist is used in order to reduce adhesion of foreign matter to the support film and sticking of the photomask. In order to sufficiently reduce the minute defects generated in the support film, a support film in which the total number of particles having a diameter of 5 μm or more and aggregates having a diameter of 5 μm or more contained in the support film is 5 / mm ² or less is used. (For example, see Patent Documents 1 and 2).

International Publication No. 08/075755 International Publication No. 08/093643

  By the way, as an apparatus for laminating a photosensitive layer, an auto-cut laminator is widely used in order to improve productivity. However, when using an auto cut laminator, scratches may occur on the surface of the support film.

  When there is a scratch on the support film, light is scattered by the scratch at the time of exposure, so that the progress of the photocuring reaction directly under the scratch is inhibited.

  In recent years, there has been a tendency to increase the use of projection exposure machines and direct drawing exposure machines. When a projection type exposure machine is used, the exposure illuminance tends to be higher and the exposure time tends to be shorter than that of a contact type exposure machine used conventionally. Furthermore, when a direct drawing type exposure machine is used, the exposure time per unit area tends to be significantly shorter than that of a contact type exposure machine.

  Even if the support film has scratches, if the exposure time is long, the photosensitive layer directly under the scratches is not scattered and the photocuring reaction due to the transmitted light is insufficient, but proceeds due to chain reaction from the peripheral part. As curing proceeds, there is a tendency that defects (disconnection failure) are less likely to occur in the resist after development. However, as the exposure time is shortened, the chain reaction from the peripheral portion becomes difficult to proceed, and it has been found by the inventors that the resist after development tends to have defects.

  The present invention has been made in view of the above circumstances, and provides a photosensitive element capable of sufficiently suppressing scratches generated in a support film in a photosensitive element including a support film, and a resist pattern using the same. The formation method of this and the manufacturing method of a printed wiring board are provided.

  The present invention is a photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein a self-healing layer or a hard code layer is provided on the surface of the support film opposite to the surface in contact with the photosensitive layer. And the layer made of the photosensitive resin composition is a photosensitive element containing (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator. .

Further, in the present invention, the haze of the support film is preferably 0.01 to 2.0%, and the total number of particles having a diameter of 5 μm or more and aggregates having a diameter of 5 μm or more contained in the support film is More preferably 5 pieces / mm ² or less.

  Furthermore, the present invention provides a laminating step of laminating the photosensitive element on a substrate, an exposure step of irradiating a predetermined portion of the photosensitive layer with actinic rays to form a photocured portion, and other than the photocured portion. And a developing process for removing the region.

  The present invention also relates to a method for manufacturing a printed wiring board, including a step of etching or plating a substrate on which a resist pattern is formed by the method for forming a resist pattern.

  This inventor examined in detail about the cause which a damage | wound produces in a support film. First, it was confirmed that there was no scratch on the support film alone, but no scratch was found. Next, it was confirmed that there was no scratch on the support film in the state where the photosensitive element was formed, but the scratch could not be found. Thereby, when it sees as a photosensitive element, it is hard to think that a crack exists in a support film from the beginning.

  Next, it was verified whether scratches occurred in the process of using the photosensitive element. When using an auto-cut laminator, the part that comes into contact with the support film is a roll for transporting the photosensitive element, a metal plate for holding the photosensitive element after cutting the photosensitive element to a specified length, and the photosensitive element There are rolls for laminating the film on the substrate. Since the conveyance roll and the laminating roll are driven and speed-controlled, it was confirmed that the support film hardly caused any scratches.

  On the other hand, since the auto-cut laminator device holds the photosensitive element after being cut to a specified length, there is a timing when the support film is conveyed while the surface opposite to the surface in contact with the photosensitive layer is in contact with the metal plate. Since the photosensitive element is vacuum-adsorbed on the metal plate, it has been found that when the photosensitive element advances, the metal plate and the support film rub against each other, and scratches are generated in the traveling direction of the photosensitive element. When the surface of the substrate (support film) after the lamination was observed, it was found that scratches were generated on the support film surface parallel to the length direction of the photosensitive element.

  On the other hand, it was confirmed that when a manual laminator or a roll-to-roll laminator having no metal plate for vacuum-adsorbing the photosensitive element was used, the support film surface was hardly damaged.

  Using a substrate after lamination in which no scratch was generated on the support film, it was verified whether the support film was damaged in the cleaning process and the exposure process. As a result, in the cleaning process, it was found that the roll for transporting the substrate and the cleaning roll are controlled in speed, so that the support film is hardly damaged. Also in the exposure process, the speed of the transport roll is controlled, and the substrate is vacuumed and lifted by an arm or the like that is held to move the substrate. In addition, since the material that comes into contact with the substrate is often made of silicone rubber or the like, it has been found that the support film is hardly damaged.

From the above examination results, it was confirmed that the process of generating scratches on the support film was a laminating process and was caused by the metal plate (rear end suction guide in FIG. 4) on which the photosensitive element was vacuum-adsorbed.
Next, the present inventors diligently examined the support film. Various materials are used as a support film for a photosensitive element (see, for example, Patent Documents 1 and 2).

  In the photosensitive element using the support film of the said patent document 1 or 2, it turned out that a crack may generate | occur | produce in a support film by using an autocut laminator. As a result of various studies, a support film provided with a self-healing layer capable of repairing scratches even if scratches occur on at least the surface of the support film that is in contact with the photosensitive layer, or a hard coat layer that is difficult to generate scratches. It has been found that the above problems can be solved by employing the provided support film, and the present invention has been completed.

  According to the present invention, an auto-cut laminator is provided by providing a photosensitive element having a support film provided with a self-healing layer or a hard coat layer on at least the surface of the support film opposite to the surface in contact with the photosensitive layer. Scratches that occur during use can be sufficiently suppressed, and resist defects caused by scratches on the support film can be sufficiently reduced. By using this, a resist pattern that does not have resist defects can be formed. It is.

It is a schematic cross section which shows suitable embodiment of the photosensitive element of this invention. It is the microscope picture which observed the crack which generate | occur | produced in the support film. It is a scanning microscope picture of the resist pattern formed using the photosensitive element provided with the photosensitive layer on the support film in which the crack generate | occur | produced. It is a schematic cross section which shows an auto cut laminator.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. The positional relationship such as up, down, left, and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios. In addition, “(meth) acrylate” in the present specification means “acrylate” and “methacrylate” corresponding thereto. Similarly, “(meth) acryl” means “acryl” and “methacryl”, and “(meth) acryloyl” means “acryloyl” and “methacryloyl”.

  FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the photosensitive element of the present invention. The photosensitive element 1 shown in FIG. 1 includes a support film 10 and a photosensitive layer (photosensitive resin composition layer) 20. The photosensitive layer 20 is provided on the first main surface 12 of the support film 10. The support film 10 has a second main surface 14 on the side opposite to the first main surface 12.

(Support film)
The support film 10 used in the present invention has a self-healing layer or a hard coat layer on at least the second main surface 14.

  The support film 10 is a component (suction guide) that holds the film by vacuum suction when the photosensitive element is laminated to the substrate while the photosensitive element is cut to a specified length and held in a laminator process or the like. Etc.), the support film is scratched, the scratch generated during the exposure causes light scattering, and the resist after development is easily damaged. And when such a photosensitive element is used for a printed wiring board, it becomes a cause of the open defect at the time of an etching, and the short defect generation | occurrence | production at the time of plating, and there exists a tendency for the manufacture yield of a printed wiring board to fall.

  The support film preferably has a haze of 0.01 to 2.0% for the purpose of reducing rattling after resist patterning. As the haze becomes smaller, the surface of the support film becomes smooth, the slipperiness tends to deteriorate, and the support film tends to be damaged. Therefore, there is a tendency that scratches are likely to occur on the second main surface of the support film.

  If a self-healing layer is provided on the second main surface of the support film, scratches caused by rubbing of the support film on the suction guide or the like disappear or become smaller, so that the possibility of causing problems during exposure tends to be greatly reduced. is there.

  In addition, if a hard coat layer that is difficult to generate scratches is provided on the second main surface of the support film, even if the support film rubs against the suction guide, etc., scratches will hardly occur and the possibility of causing problems during exposure is greatly increased. There is a tendency to reduce.

The support film used in the present invention preferably has a total number of particles and aggregates (hereinafter simply referred to as “particles”) having a diameter of 5 μm or more contained in the support film 10 of 5 / mm ² or less. . Here, the particles having a diameter of 5 μm or more included in the support film 10 include both those protruding from the main surface of the support film and those existing inside the film. In addition, particles having a diameter of 5 μm or more include aggregates of primary particles having a diameter of 5 μm or more and primary particles having a diameter of less than 5 μm.

The number of particles having a diameter of 5 μm or more is preferably 5 / mm ² or less, more preferably 3 / mm ² or less, and even more preferably 1 / mm ² or less. When the number of particles and the like exceeds 5 / mm ² , partial defect (resist minute defect) of the resist after exposure and development tends to occur. And when such a photosensitive element is used for a printed wiring board, it becomes a cause of the open defect at the time of an etching, and the short defect generation | occurrence | production at the time of plating, and there exists a tendency for the manufacture yield of a printed wiring board to fall.

  Even if many particles having a diameter of less than 5 μm are included in the support film 10, the influence on light scattering is not great. The reason is that in the exposure process, when the photosensitive layer is irradiated with light, the photocuring reaction of the photosensitive layer is not only in the light irradiation part, but in a lateral direction where light is not directly irradiated (relative to the light irradiation direction). It also proceeds in the vertical direction. For this reason, when the particle size is small, the photocuring reaction directly under the particle proceeds sufficiently, but as the particle size increases, the photocuring reaction directly under the particle does not proceed sufficiently, resulting in resist microdefects. I think that.

Here, the particles having a diameter of 5 μm or more contained in the support film 10 are components constituting the support film, for example, a polymer gel, a monomer as a raw material, a catalyst used in production, and as necessary. Agglomerates formed by aggregation of inorganic or organic fine particles contained during film production, swelling with lubricant and adhesive generated when a lubricant-containing layer is applied on the film, particles having a diameter of 5 μm or more contained in the film, etc. It is caused by this. In order to reduce the number of particles having a diameter of 5 μm or more to 5 particles / mm ² or less, among these particles, particles having a small particle diameter or excellent dispersibility may be selectively used.

  The number of particles having a diameter of 5 μm or more can be measured using a polarizing microscope. In addition, the aggregate formed by aggregating primary particles having a diameter of 5 μm or more and primary particles having a diameter of less than 5 μm is counted as one.

  The support film 10 can be used without any particular limitation. Examples thereof include polyethylene terephthalate (hereinafter referred to as “PET”), polybutylene terephthalate (PBT), polyester such as polyethylene-2,6-naphthalate (PEN), and polyolefin such as polypropylene and polyethylene. The support film may be a single layer or a multilayer.

  On the support film, a self-healing layer or a hard coat layer can be formed using a known method such as a roll coater, a flow coater, a spray coater, a curtain flow coater, a dip coater, or a slit die coater. . The hard coat layer is preferably a curable composition, and can be formed by applying an appropriate curable compound and then curing.

  The haze of the support film 10 is preferably 0.01 to 2.0%, more preferably 0.01 to 1.5%, and particularly preferably 0.01 to 1.0%. 0.01 to 0.5% is very preferable. If the haze is less than 0.01%, the production of the support film itself tends to be difficult, and if it exceeds 2.0%, the sensitivity and the resolution tend to decrease. Here, “haze” means haze. The haze in the present invention refers to a value measured using a commercially available haze meter (turbidimeter) in accordance with the method defined in JIS K 7105. Haze can be measured with a commercially available turbidimeter such as NDH-5000 (trade name, manufactured by Nippon Denshoku Industries Co., Ltd.).

  The thickness of the support film 10 is preferably 5 to 200 μm, more preferably 8 to 100 μm, still more preferably 10 to 50 μm, and particularly preferably 12 to 30 μm. When the thickness is less than 5 μm, the support film 10 tends to be easily broken when the support film 10 is peeled from the photosensitive element 1. Moreover, when thickness exceeds 200 micrometers, there exists a tendency for it to be inferior to cheapness.

  Moreover, the support film 10 may be obtained by using a commercially available film for general industrial use that can be used as a support film for the photosensitive element 1, and may be appropriately processed and used. Moreover, you may use the commercially available industrial film which has a self-healing layer or a hard-coat layer previously. Specifically, for example, “SR1” (trade name, manufactured by Toray Film Processing Co., Ltd.) which is a PET film having a self-healing layer and “THS” (trade name, manufactured by Toray Film Processing Co., Ltd.) having a hard coat layer. ).

(Self-healing layer)
The self-healing layer is a layer made of a soft resin having a property that a dent mark once generated disappears with time and returns to its original shape. Self-healing results from the fact that the wound is reversibly deformed (elastically deformed). The excellent self-healing property is achieved by the fact that the resin forming the self-healing layer has an elastic deformation region up to high stress, that is, excellent toughness (toughness). . Moreover, a reactive diluent, a photoinitiator, a solvent, etc. can be added to a self-healing layer with resin.

  The self-healing layer can be formed by curing a photocurable resin or a thermosetting resin. Examples of the resin include unsaturated acrylic resins, urethane-modified (meth) acrylate compounds, epoxy (meth) acrylate compounds, unsaturated polyester resins, polyamide resins, thermosetting silicone resins, melamine resins, and epoxy resin compositions. Products, oxetane compounds, vinyl ether compounds, and the like.

  Examples of the resin for forming the self-healing layer include JP-A-60-222249, JP-A-61-281118, JP-A-2003-4939, JP-A-2003-84102, JP-A-9-71636, Known ones in JP 2006-124653, JP 2007-207091 and JP 2007-284613 may be used.

  The self-healing layer is applied with a coating solution, for example, spin coating method, brush coating, spray method (spraying), dip coating method, blade coating method, roll coating method, ink jet printing, gravure printing, screen.

Although the thickness of a self-healing layer changes with uses and is not specifically limited, For example, 0.1-10 micrometers is preferable and 1-5 micrometers is more preferable. The self-healing property was tested by placing 200 g of weight on steel wool (# 0000, manufactured by Nippon Steel Wool Co., Ltd.) (load area 20 cm ² ) and rubbing the coating surface (self-healing layer surface) 20 times. It can be evaluated by the change in the haze value (decrease with time) of the coating surface immediately after the test. The haze value after 2 hours is preferably decreased with respect to the haze value immediately after abrasion, and more preferably 3% or more.

(Hard coat layer)
The hard coat layer can be formed, for example, by coating and drying the particles and the photocurable resin composition with various coaters and then curing the resin. The material for the hard coat layer may be a conventionally known material and is not particularly limited.

  Examples of the photocurable resin composition include a photocurable resin composition containing a compound having an ethylenically unsaturated group and a photopolymerization initiator. Examples of the ethylenically unsaturated group include a (meth) acryloyloxy group, a vinyl group, and an allyl group. Among these, a (meth) acryloyloxy group is preferable from the viewpoint of curability.

  Examples of the particles include organic fillers such as acrylic beads and urethane beads, inorganic fillers such as silica and titanium, and inorganic fillers that have been surface-organized with a silane coupling agent or the like.

  The film provided with the self-healing layer or hard coat layer used in the present invention is commercially available as described above, and a film that can be used as a support film for the photosensitive element is obtained from commercially available general industrial films. It is preferable to use after appropriately processing.

(Photosensitive layer)
The photosensitive layer 20 is a layer made of a photosensitive resin composition. The photosensitive resin composition constituting the photosensitive layer 20 contains (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator. Hereafter, each said component is demonstrated in detail.

((A) binder polymer)
The binder polymer as component (A) is not particularly limited as long as it is used in conventional photosensitive resin compositions. For example, acrylic resin, styrene resin, epoxy resin, amide resin, amide epoxy resin , Alkyd resin and phenol resin. Among these, an acrylic resin is preferable from the viewpoint of alkali developability. These are used singly or in combination of two or more.

  The binder polymer can be produced by radical polymerization of a polymerizable monomer. Examples of the polymerizable monomer include styrene, (meth) acrylic acid alkyl ester, (meth) acrylic acid benzyl ester, (meth) acrylic acid tetrahydrofurfuryl ester, (meth) acrylic acid glycidyl ester, and maleic acid.

  The binder polymer preferably has a carboxyl group in the molecule from the viewpoint of alkali developability. The binder polymer having a carboxyl group can be produced by radical polymerization of a polymerizable monomer having a carboxyl group and another polymerizable monomer. As the polymerizable monomer having a carboxyl group, methacrylic acid is preferable. Especially, the binder polymer which has (meth) acrylic-acid alkylester and (meth) acrylic acid as a monomer unit is preferable.

((B) Photopolymerizable compound having an ethylenically unsaturated bond)
(B) As a photopolymerizable compound which has an ethylenically unsaturated bond which is a component, it is preferable to contain the compound which has 4-40 oxyalkylene units (alkylene glycol unit) of C2-C6 in a molecule | numerator. By containing such a compound as the component (B), compatibility with the (A) binder polymer can be improved.

  Examples of the oxyalkylene unit having 2 to 6 carbon atoms include an oxyethylene unit, an oxypropylene unit, an oxyisopropylene unit, an oxybutylene unit, an oxypentylene unit, and an oxyhexylene unit. The alkylene unit is preferably an oxyethylene unit or an oxyisopropylene unit from the viewpoint of improving resolution and plating resistance.

  Among these photopolymerizable compounds, bisphenol A (meth) acrylate compounds or polyalkylene glycol di (meth) acrylates are particularly preferably used because the effects of the present invention tend to be obtained more reliably. it can.

  Preferred examples of the bisphenol A (meth) acrylate compound include compounds represented by the following general formula (I).

上記一般式（Ｉ）中、Ｒ^１及びＲ^２は、それぞれ独立に水素原子又はメチル基を示し、メチル基であることが好ましい。上記一般式（Ｉ）中、Ｘ^１及びＸ^２はそれぞれ独立に炭素数２〜６のアルキレン基を示す。上記一般式（Ｉ）中、ｐ及びｑは、ｐ＋ｑ＝１〜４０を示す。ｐ＋ｑの値は２〜４０であることが好ましく、４〜４０であることがより好ましく、５〜３０であることがさらに好ましく、８〜２０であることが特に好ましく、８〜１６であることが極めて好ましく、８〜１２であることが最も好ましい。なお、ｐ及びｑは構成単位の構成単位数を示す。従って単一の分子においては整数値を示し、複数種の分子の集合体としては平均値である有理数を示す。以下、構成単位の構成単位数については同様である。

In the general formula (I), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, and preferably a methyl group. In the general formula (I), X ¹ and X ² each independently represent an alkylene group having 2 to 6 carbon atoms. In said general formula (I), p and q show p + q = 1-40. The value of p + q is preferably 2 to 40, more preferably 4 to 40, still more preferably 5 to 30, particularly preferably 8 to 20, and preferably 8 to 16. Very preferred, most preferred is 8-12. Here, p and q indicate the number of structural units. Therefore, an integer value is shown in a single molecule, and a rational number that is an average value is shown as an aggregate of a plurality of types of molecules. Hereinafter, the same applies to the number of structural units.

  When the value of p + q is less than 4, the compatibility with the binder polymer as the component (A) is lowered and tends to be peeled off when the photosensitive element is laminated on the circuit forming substrate. On the other hand, if the value of p + q exceeds 40, the hydrophilicity increases, the resist image tends to be peeled off during development, and the plating resistance against solder plating or the like tends to decrease. In either case, the resolution of the photosensitive element tends to decrease.

  Examples of the alkylene group having 2 to 6 carbon atoms include an ethylene group, a propylene group, an isopropylene group, a butylene group, a pentylene group, and a hexylene group. Among these, from the viewpoint of improving resolution and plating resistance, an ethylene group or an isopropylene group is preferable.

  Examples of the compound represented by the general formula (I) include 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane, 2,2-bis (4-((meth) acrylic). Loxypolypropoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolybutoxy) phenyl) propane, 2,2-bis (4-((meth) acryloxypolyethoxypolypropoxy) phenyl) Examples thereof include bisphenol A-based (meth) acrylate compounds such as propane.

  Examples of 2,2-bis (4-((meth) acryloxypolyethoxy) phenyl) propane include 2,2-bis (4-((meth) acryloxydiethoxy) phenyl) propane, 2,2- Bis (4-((meth) acryloxypentaethoxy) phenyl) propane, 2,2-bis (4- (methacryloxypentadecaethoxy) phenyl) propane, and the like can be given. Of these, 2,2-bis (4- (methacryloxypentaethoxy) phenyl) propane is commercially available as BPE-500 (product name, manufactured by Shin-Nakamura Chemical Co., Ltd.). 2,2-bis (4- (methacryloxypentadecaethoxy) phenyl) propane is commercially available as BPE-1300 (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). These may be used alone or in combination of two or more.

  Examples of the polyalkylene glycol di (meth) acrylate include compounds represented by the following general formulas (II), (III), and (IV). These can be used individually by 1 type or in combination of 2 or more types.

In general formula (II), R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, EO represents an oxyethylene unit, PO represents an oxypropylene unit, m ¹ , m ² and n ¹ represent m ¹ + m ² + n ¹ = 4 to 40.

In general formula (III), R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, EO represents an oxyethylene unit, PO represents an oxypropylene unit, m ³ , n ² and ^{n 3} represents an ^{m 3 + n 2 + n 3} = 4~40.

In general formula (IV), R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, EO represents an oxyethylene unit, PO represents an oxypropylene unit, m ⁴ and n ^{4 represents} an m ⁴ + n ⁴ = 4~40.

Examples of the alkyl group having 1 to 3 carbon atoms in the general formulas (II), (III), and (IV) include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group, and a methyl group is preferable. The total number of structural units (m ¹ + m ² , m ³ and m ⁴ ) of the oxyethylene group in the general formulas (II), (III) and (IV) is preferably 1 to 30 each independently. It is more preferably 1 to 10, more preferably 4 to 9, and particularly preferably 5 to 8. If the total number of structural units exceeds 30, the tent reliability and the resist shape tend to deteriorate.

The total number (n ¹ , n ² + n ³ and n ⁴ ) of the structural units of the oxypropylene group in the general formulas (II), (III) and (IV) is preferably 1 to 30 each independently. More preferably, it is -20, It is still more preferable that it is 8-16, It is especially preferable that it is 10-14. If the total number of structural units exceeds 30, the resolution tends to deteriorate and sludge tends to occur.

Specific examples of the compound represented by the general formula (II) include, for example, vinyl in which R ³ and R ⁴ are a methyl group, m ¹ + m ² = 4 (average value), and n ¹ = 12 (average value). A compound (trade name: FA-023M, manufactured by Hitachi Chemical Co., Ltd.).

Specific examples of the compound represented by the general formula (III) include, for example, vinyl in which R ³ and R ⁴ are methyl groups, m ³ = 6 (average value), n ² + n ³ = 12 (average value) Compound (manufactured by Hitachi Chemical Co., Ltd., trade name: FA-024M).

Specific examples of the compound represented by the general formula (IV) include a vinyl compound in which R ³ and R ⁴ are hydrogen atoms, m ⁴ = 1 (average value), and n ⁴ = 9 (average value) ( Shin Nakamura Chemical Co., Ltd., NK ester HEMA-9P). In addition, these are used individually by 1 type or in combination of 2 or more types.

((C) Photopolymerization initiator)
Examples of the photopolymerization initiator as component (C) include N, N′-tetraalkyl-4,4′- such as benzophenone; N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone). Fragrance such as diaminobenzophenone; 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone-1 Group ketones; quinone compounds such as alkyl anthraquinones; benzoin ether compounds such as benzoin alkyl ethers; benzoin compounds such as benzoin and alkyl benzoins; benzyl derivatives such as benzyldimethyl ketal; 2- (o-chlorophenyl) -4,5-diphenylimidazole Dimer, 2- (o-chlorophenyl) -4,5 Di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- 2,4,5-triarylimidazole dimer such as (p-methoxyphenyl) -4,5-diphenylimidazole dimer; 9-phenylacridine, 1,7-bis (9,9'-acridinyl) heptane And acridine derivatives such as N-phenylglycine, N-phenylglycine derivatives, and coumarin compounds. Among these, 2,4,5-triarylimidazole dimer is preferable from the viewpoint of improving adhesion and sensitivity. These are used individually by 1 type or in combination of 2 or more types.

  The blending amount of the binder polymer as component (A) is preferably 40 to 70 parts by mass, and 50 to 60 parts by mass with respect to 100 parts by mass as the total of component (A) and component (B). Is more preferable. If the blending amount is less than 40 parts by mass, the photocured product tends to be brittle, and if it exceeds 70 parts by mass, the resolution and photosensitivity tend to be insufficient.

  It is preferable that the compounding quantity of the photopolymerizable compound which has an ethylenically unsaturated bond which is (B) component is 30-60 mass parts with respect to 100 mass parts of total amounts of (A) component and (B) component. It is more preferable that it is 40-50 mass parts. If the blending amount is less than 30 parts by mass, resolution and photosensitivity tend to be insufficient, and if it exceeds 60 parts by mass, the photocured product tends to be brittle.

  The blending amount of the photopolymerization initiator (C) is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass as the total of the components (A) and (B), and is 0.2 to More preferably, it is 10 mass parts, and it is especially preferable that it is 0.5-5 mass parts. If the blending amount is less than 0.1 parts by mass, the photosensitivity tends to be insufficient, and if it exceeds 20 parts by mass, the light absorption on the surface of the photosensitive resin composition increases during the exposure, and the internal Photocuring tends to be inadequate.

  In addition, the photosensitive resin composition may include a photopolymerizable compound (oxetane compound or the like) having at least one cationically polymerizable cyclic ether group in the molecule, a cationic polymerization initiator, a dye such as malachite green, if necessary. , Photochromic agents such as tribromophenylsulfone and leucocrystal violet, thermochromic inhibitors, plasticizers such as p-toluenesulfonamide, pigments, fillers, antifoaming agents, flame retardants, stabilizers, adhesion-imparting agents, You may contain additives, such as a leveling agent, peeling promoter, antioxidant, a fragrance | flavor, an imaging agent, and a thermal crosslinking agent. These are used singly or in combination of two or more. These additives may be contained in an amount of about 0.01 to 20 parts by mass per 100 parts by mass of the total amount of the component (A) and the component (B) as long as the object of the present invention is not impaired.

  The photosensitive resin composition is dissolved in a solvent such as methanol, ethanol, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, toluene, N, N-dimethylformamide and propylene glycol monomethyl ether, or a mixed solvent thereof, as necessary. Thus, it can be prepared as a solution having a solid content of about 30 to 60% by mass.

  The photosensitive layer 20 in the photosensitive element 1 of the present invention can be formed by applying the above-described photosensitive resin composition on the support film 10 and removing the solvent. Here, as a coating method, for example, a known method such as roll coating, comma coating, gravure coating, air knife coating, die coating, or bar coating can be employed. Moreover, the removal of a solvent can be performed by processing at 70-150 degreeC for about 5 to 30 minutes, for example. The amount of the remaining organic solvent in the photosensitive layer 20 is preferably 2% by mass or less from the viewpoint of preventing the organic solvent from diffusing in a later step.

  The photosensitive element 1 may include a protective film (not shown) on the opposite side of the photosensitive layer 20 from the support film 10. As the protective film, it is preferable to use a film in which the adhesive force between the photosensitive layer 20 and the protective film is smaller than the adhesive force between the photosensitive layer 20 and the support film 10. It is preferable to use the film. Specific examples include inert polyolefin films such as polyethylene and polypropylene. From the viewpoint of peelability from the photosensitive layer 20, a polyethylene film is preferable. Although the thickness of a protective film changes with uses, it is preferable that it is about 1-100 micrometers.

  The photosensitive element 1 may further include an intermediate layer or a protective layer such as a cushion layer, an adhesive layer, a light absorption layer, and a gas barrier layer in addition to the support film 10, the photosensitive layer 20, and the protective film.

  The photosensitive element 1 of the present embodiment may be stored, for example, as it is or in a state where a protective film further laminated on the photosensitive layer 20 is wound around a cylindrical core. At this time, the support film 10 is preferably wound into a roll shape so as to be the outermost layer.

(Method for forming resist pattern)
The resist pattern forming method of the present embodiment includes a lamination step of laminating the photosensitive element 1 on the substrate in the order of the photosensitive layer 20 and the support film 10, and a predetermined amount of the photosensitive layer 20 through the support film 10 with actinic rays. This is a method including an exposure step of irradiating a portion to form a photocured portion on the photosensitive layer 20 and a developing step of removing a region other than the photocured portion.

  In the laminating step, as a method of laminating the photosensitive layer 20 on the substrate, when a protective film is present on the photosensitive layer 20, the protective layer is removed, and then the photosensitive layer 20 is about 70 to 130 ° C. And a method of laminating the substrate by pressure bonding to the substrate with a pressure of about 0.1 to 1 MPa. In this lamination step, lamination can also be performed under reduced pressure. In addition, although the surface on which a board | substrate is laminated | stacked is a metal surface normally, it does not restrict | limit in particular. In addition, in order to further improve the stackability, the substrate may be preheated.

  Next, a photomask having a negative or positive mask pattern is aligned and brought into close contact with the second main surface 14 of the support film 10 with respect to the photosensitive layer 20 that has been laminated in the laminating step. Thereafter, in the exposure step, the photosensitive layer 20 is irradiated with an actinic ray in an image form through the support film 10 to form a photocured portion on the photosensitive layer 20. As the light source of the actinic light, a known light source such as a carbon arc lamp, a mercury vapor arc lamp, a high pressure mercury lamp, a xenon lamp, or the like that effectively emits ultraviolet rays or visible light is used. A laser direct drawing exposure method can also be used.

  Next, after the exposure step, the photomask is peeled off from the support film 10. Further, the support film 10 is peeled off from the photosensitive layer 20. Next, in the development process, the unexposed portion (unphotocured portion) of the photosensitive layer 20 is removed and developed by wet development using a developer such as an alkaline aqueous solution, an aqueous developer, an organic solvent, or dry development, and a resist pattern is developed. Can be manufactured.

  Examples of the alkaline aqueous solution include 0.1 to 5% by mass sodium carbonate solution, 0.1 to 5% by mass potassium carbonate solution, and 0.1 to 5% by mass sodium hydroxide solution. The pH of the alkaline aqueous solution is preferably in the range of 9 to 11, and the temperature is adjusted according to the developability of the photosensitive layer 20. Further, a surfactant, an antifoaming agent, and an organic solvent may be mixed in the alkaline aqueous solution. Examples of the development method include a dip method, a spray method, brushing, and slapping.

Moreover, as a process after a development process, you may further harden a resist pattern by performing about 60-250 degreeC heating or about 0.2-10 J / cm < ² > exposure as needed.

  By the above method, a resist pattern can be formed on the conductor layer on which the circuit pattern is formed. The resist pattern can be used as a solder resist for preventing solder from adhering to unnecessary portions on the conductor layer when mounting components are joined.

  In addition, the resist pattern obtained by the above-described forming method may be used to form a cured resin having excellent physical properties such as tensile strength and elongation and satisfying the electric corrosion resistance on a rigid substrate. It is more preferable that it is used as a permanent mask (solder resist) formed on a rigid substrate. Specifically, it is useful when used as a solder resist for a printed wiring board having a rigid substrate or a solder resist for a package substrate having a rigid substrate.

(Printed wiring board manufacturing method)
The method for producing a printed wiring board of the present embodiment is performed by etching or plating a substrate on which a resist pattern is formed by the resist pattern forming method. Here, the etching or plating of the substrate is performed by etching or plating the surface of the substrate by a known method using the developed resist pattern as a mask.

  As an etching solution used for etching, for example, a cupric chloride solution, a ferric chloride solution, or an alkaline etching solution can be used. Examples of the plating include copper plating, solder plating, nickel plating, and gold plating.

  After etching or plating, the resist pattern can be peeled off with a stronger alkaline aqueous solution than the alkaline aqueous solution used for development, for example. As this strongly alkaline aqueous solution, for example, a 1 to 10% by mass sodium hydroxide aqueous solution and a 1 to 10% by mass potassium hydroxide aqueous solution are used. Examples of the peeling method include an immersion method and a spray method. The printed wiring board on which the resist pattern is formed may be a multilayer printed wiring board or may have a small diameter through hole.

  Moreover, when plating is performed on a substrate including an insulating layer and a conductor layer formed on the insulating layer, it is necessary to remove the conductor layers other than the pattern. As this removal method, for example, a method of lightly etching after removing the resist pattern, or performing solder plating after the above plating, and then masking the wiring portion with solder by peeling off the resist pattern, and then conducting layer The method of processing using the etching liquid which can etch only is mentioned.

(Method for manufacturing semiconductor package substrate)
The photosensitive element 1 of the present invention can also be used for a package substrate including a rigid substrate and an insulating film formed on the rigid substrate. In this case, the photocured portion of the photosensitive layer may be used as the insulating film. When the photocured portion of the photosensitive layer is used as, for example, a solder resist for a semiconductor package, after the development in the above-described resist pattern forming method, a high pressure mercury lamp is used for the purpose of improving solder heat resistance, chemical resistance, etc. It is preferable to perform ultraviolet irradiation or heating. In the case of irradiating ultraviolet rays, the irradiation amount can be adjusted as necessary. For example, the irradiation can be performed at an irradiation amount of about 0.2 to 10 J / cm ² . Moreover, when heating a resist pattern, it is preferable to carry out for about 15 to 90 minutes in the range of about 100-170 degreeC. Furthermore, ultraviolet irradiation and heating can be performed at the same time, and after either one is performed, the other can be performed. When performing ultraviolet irradiation and heating simultaneously, it is more preferable to heat to 60 to 150 ° C. from the viewpoint of effectively imparting solder heat resistance, chemical resistance and the like.

This solder resist is effective as a permanent mask for semiconductor packages because it also serves as a protective film for wiring after soldering to the substrate and has excellent physical properties such as tensile strength and elongation and thermal shock resistance. .
The package substrate provided with the resist pattern in this manner is then mounted with a semiconductor element or the like (for example, wire bonding or solder connection) and then mounted on an electronic device such as a personal computer.

  According to the photosensitive element, resist pattern forming method, printed wiring board, and semiconductor package substrate manufacturing method of the present embodiment, a self-healing layer or a hard coat layer is provided on the surface of the support film opposite to the surface in contact with the photosensitive layer. Therefore, scratches generated on the support film in the resist pattern forming step can be sufficiently suppressed, so that resist defects generated due to scratches on the support film can be sufficiently reduced. In particular, it is possible to sufficiently suppress scratches that occur when using an auto-cut laminator.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist thereof.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.
(Examples 1-2, Comparative Examples 1-4)
(Preparation of basic solution of photosensitive resin composition)
The binder polymer having the composition shown in Table 1 was synthesized according to the following synthesis example.

(Synthesis example)
To a flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas introduction tube, 420 g of a mixture of toluene and methyl cellosolve having a mass ratio of 6: 4 was added and stirred while blowing nitrogen gas, Heated to 80 ° C. Meanwhile, toluene and methyl cellosolve having a mass ratio of 6: 4 prepared by mixing a predetermined material shown in Table 1 as a comonomer (hereinafter referred to as “solution a”) and heated to 80 ° C. After the solution a was dropped into the above formulation over 4 hours, the dropping funnel was washed with 40 g of toluene and methyl cellosolve having a mass ratio of 6: 4 and added to the flask. Next, the mixture was kept at 80 ° C. with stirring for 2 hours. Furthermore, a solution in which 1.0 g of azobisisobutyronitrile was dissolved in 40 g of a mixture of methyl cellosolve and toluene having a mass ratio of 6: 4 was dropped into the flask over 30 minutes. The dropping funnel was washed with 120 g of a mixture of toluene and methyl cellosolve having a mass ratio of 6: 4 and added to the solution a. The solution after dropping was kept at 80 ° C. for 3 hours with stirring, and then heated to 90 ° C. over 30 minutes. The mixture was kept at 90 ° C. for 2 hours and then cooled to obtain a binder polymer solution as component (A). Toluene was added to this binder polymer solution to prepare a nonvolatile component concentration (solid content concentration) of 40% by mass. The weight average molecular weight of the binder polymer was measured, and the measurement results are shown in Table 1. The weight average molecular weight was measured by a gel permeation chromatography (GPC) method and calculated by using a standard polystyrene calibration curve. The GPC conditions are shown below. The acid value was also measured according to the following measurement procedure, and the measurement results are shown in Table 1.

(GPC conditions)
Pump: Hitachi L-6000 type [manufactured by Hitachi, Ltd.]
Column: Gelpack GL-R420 + Gelpack GL-R430 + Gelpack GL-R440 (three in total) [above, manufactured by Hitachi Chemical Co., Ltd., product name]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI [manufactured by Hitachi, Ltd., product name]

(Acid value measuring method)
Weigh the binder polymer synthesized in an Erlenmeyer flask, add and dissolve a mixed solvent (mass ratio: toluene / methanol = 70/30), add a phenolphthalein solution as an indicator, and titrate with an N / 10 potassium hydroxide alcohol solution. Then, the acid value was measured.
Each component shown in the following Table 2 was blended to prepare a solution of the photosensitive resin composition.

(Production of photosensitive element)
The PET film shown in Table 3 was prepared as a support film for the photosensitive element. Table 3 shows the results of measuring the number, haze, and transmittance of particles of 5 μm or more contained in each PET film.

The number of particles and the like is a value obtained by measuring the number of particles and the like of 5 μm or more existing in 1 mm ² units using a polarizing microscope. The number of measurements (n number) at that time was 5.
The haze and transmittance are values measured using a haze meter MDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

  Next, the above photosensitive resin composition solution was applied on each PET film so as to have a uniform thickness, and dried for 2 minutes in a hot air convection dryer at 100 ° C. to remove the solvent. After drying, the photosensitive layer was covered with a protective film made of polyethylene (manufactured by Tamapoly Co., Ltd., trade name “NF-15”, thickness 20 μm) to obtain a photosensitive element. In addition, the thickness of the layer of the photosensitive resin composition after drying was 25 μm.

  When the PET film had a self-healing layer or a hard coat layer, a layer of the photosensitive resin composition was formed on the opposite surface of these layers. In the case of PET films having different structures on the front and back sides, a layer of the photosensitive resin composition was formed on the surface opposite to the lubricant layer.

(Production of laminate)
The copper surface of a double-sided copper-clad laminate (manufactured by Hitachi Chemical Co., Ltd., trade name “MLC-E-679”), which is a glass epoxy material in which copper foil (thickness: 35 μm) is laminated on both sides, is a MEC etch bond CZ Surface roughening was performed using -8100 (manufactured by MEC Co., Ltd.), pickling and rinsing, followed by drying with an air stream. The obtained copper-clad laminate was heated to 80 ° C., and the photosensitive element was laminated so that the layer of the photosensitive resin composition was in contact with the copper surface while peeling off the protective film. In this way, the laminated body laminated | stacked in order of the copper clad laminated board, the layer of the photosensitive resin composition, and the support film was obtained. Lamination was performed using a 120 ° C. heat roll at a pressure of 0.4 MPa and a roll speed of 1.5 m / min. These laminates were used as test pieces in the following tests. An auto-cut laminator HLM-A60LCD (manufactured by Hitachi Chemical Electronics Co., Ltd.) was used as the laminator.

(Measurement of minimum development time)
The layer of the photosensitive resin composition laminated on the 125 mm × 200 mm square substrate was spray-developed, and the time required for completely removing the unexposed portion was measured to obtain the minimum development time. The measurement results are shown in Table 3.

(Photosensitivity measurement test)
On the support film of the test piece, a 41-step tablet was placed as a negative, and the irradiation amount was adjusted using a projection exposure machine (UX-2240SM-XJ01, manufactured by Ushio Inc.) having a high-pressure mercury lamp. The photosensitive resin composition layer was exposed in order to obtain a predetermined amount of irradiation energy at which the number of resist curing steps after development was 11 steps.

  Next, the support film was peeled off, and a 1% by mass sodium carbonate aqueous solution at 30 ° C. was spray-developed in a time twice as long as the minimum development time, and the unexposed portion was removed for development. Then, it was confirmed that the number of steps of the step tablet of the photocured film formed on the copper-clad laminate was 11, and the predetermined irradiation energy amount (photosensitivity) of the film was shown in Table 3. It shows that photosensitivity is so high that the value of irradiation energy amount is small.

(Adhesion and resolution measurement test)
In order to investigate the adhesion and resolution, a photo tool having a 41-step tablet and a glass chrome type having a wiring pattern with a line width / space width of 2/6 to 20/90 (unit: μm) as a negative for adhesion evaluation Photolithographic tool, projection exposure machine (UX) having a high-pressure mercury lamp lamp and a glass chrome type phototool having a wiring pattern with a line width / space width of 2/2 to 20/20 (unit: μm) as a negative for resolution evaluation -2240SM-XJ01, manufactured by Ushio Electric Co., Ltd.), exposure was performed with an irradiation energy amount of 11 steps after the development of the 41-step tablet. Next, the support film was peeled off, and a 1% by mass aqueous sodium carbonate solution was spray-developed at 30 ° C. in a time twice as long as the minimum development time, and the unexposed portion was removed for development. Here, the resolution was evaluated based on the smallest value (unit: μm) of the space width between the line widths in which the unexposed portion could be removed cleanly by the development process. Note that the smaller the numerical value, the better the evaluation of resolution. The results are shown in Table 3.

(Observation of resist line)
Using the substrate evaluated in the adhesion and resolution measurement test, the resist line was observed with a scanning electron microscope SU-1500 (manufactured by Hitachi, Ltd.) for the defects as shown in FIG. The results are shown in Table 3.

SR1: PET film having a self-healing layer, THS manufactured by Toray Film Processing Co., Ltd .: PET film having a hard coat layer, FB40 manufactured by Toray Film Processing Co., Ltd .: a three-layer structure having a lubricant layer containing fine particles on the front and back Biaxially oriented PET film, A1517 manufactured by Toray Industries, Inc .: Biaxially oriented PET film having a two-layer structure having a lubricant layer containing particles on one side, A4100 manufactured by Toyobo Co., Ltd .: One lubricant layer containing particles Biaxially oriented PET film having a two-layer structure on the surface, G2H manufactured by Toyobo Co., Ltd .: biaxially oriented PET film having a single layer structure containing fine particles, manufactured by Teijin DuPont Films, Ltd.

In Comparative Examples 1 to 4 laminated with a highly productive auto-cut laminator and exposed with a projection type exposure machine, in the case of Comparative Examples 1 to 3 using a support film provided with a lubricant layer on the support film, shown in FIG. Resist line defects were observed. On the other hand, in Comparative Example 4 using the support film in which fine particles are dispersed in the support film, no resist line defect is observed, but the number of particles of 5 μm or more existing in 1 mm ² units is large, and the haze value is also high. Highly small defects in the resist were seen. On the other hand, in Examples 1 and 2 of the present invention, since a self-healing layer or a hard coat layer is provided on the surface of the support film, the generation of scratches is suppressed, and no resist line defects are observed, and other characteristics are also obtained. It is equivalent.

  According to the present invention, a photosensitive element using a support film having a self-healing layer or a hard coat layer can provide a photosensitive element capable of forming a resist pattern with sufficiently reduced resist defects and resist line defects. can do.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 10 ... Support film, 12 ... 1st main surface, 14 ... 2nd main surface, 20 ... Photosensitive layer (layer of photosensitive resin composition).

Claims (6)

  A photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein the support film has a self-healing layer on a surface opposite to a surface in contact with the photosensitive layer, and the photosensitive layer A photosensitive element comprising (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator.   A photosensitive element comprising a support film and a photosensitive layer formed on the support film, wherein the support film has a hard coat layer on a surface opposite to a surface in contact with the photosensitive layer, and the photosensitive layer A photosensitive element comprising (A) a binder polymer, (B) a photopolymerizable compound having an ethylenically unsaturated bond, and (C) a photopolymerization initiator.   The photosensitive element according to claim 1, wherein the haze of the support film is 0.01 to 2.0%. 4. The photosensitive element according to claim 1, wherein the total number of particles having a diameter of 5 μm or more and aggregates having a diameter of 5 μm or more contained in the support film is 5 / mm ² or less. A laminating step of laminating a photosensitive layer of the photosensitive element according to claim 1 on a substrate,
A resist pattern forming method comprising: an exposure step of irradiating a predetermined portion of the photosensitive layer with an actinic ray to form a photocured portion; and a developing step of removing an area other than the photocured portion.   A method for manufacturing a printed wiring board, comprising a step of etching or plating a substrate on which a resist pattern is formed by the method for forming a resist pattern according to claim 5.

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