Protective film

Abstract

To provide a protective film that can prevent chipping from occurring when a small-diameter processing hole of 0.5 mm or less in diameter is formed in a glass epoxy substrate using a drill.SOLUTION: A protective film 13 for protecting a substrate during drilling of the substrate, wherein when the protective film 13 is attached to a glass epoxy substrate and a peel test is then carried out in which the protective film 13 is peeled from the glass epoxy substrate, the peel strength between the protective film 13 and the glass epoxy substrate is at least 40 mN / 25 mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a protective film. [Background technology]

[0002] As substrate devices such as semiconductor devices become smaller and more powerful, electronic circuits are becoming denser and circuit boards are becoming thinner, and interlayer connection holes in circuit boards such as glass epoxy boards are becoming smaller in diameter and denser (Patent Documents 1 and 2, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-135644 [Patent Document 2] Japanese Patent Application Publication No. 11-251365 Summary of the Invention [Problem to be solved by the invention]

[0004] 4 is a cross-sectional view showing a typical example of drilling a substrate by a conventional method. When drilling a hole in a substrate 10 such as a glass epoxy substrate using a drill 9 during the manufacture of a semiconductor device, chipping (small chips) may occur at the entrance or exit of the drill hole.

[0005] An object of the present invention is to provide a protective film that can suppress chipping even when a small-diameter hole having a diameter of 0.5 mm or less is drilled in a glass epoxy substrate. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following configuration. [1] A protective film for protecting the substrate when drilling holes in the substrate. A protective film in which, after being attached to a glass epoxy substrate, a peel test is conducted in which the protective film is peeled off from the glass epoxy substrate, and the peel strength between the protective film and the glass epoxy substrate is 40 mN / 25 mm or more.

[0007] [2] The protective film according to [1], which is thermosetting. [3] The protective film according to [1] or [2], wherein the content of the filler (d) relative to the total mass of the protective film is 30 mass % or less. [4] The protective film according to any one of [1] to [3], which is a protective film for protecting a substrate when drilling a small hole having a diameter of 0.5 mm or less in the substrate. [Effects of the Invention]

[0008] According to the present invention, a protective film is provided that can suppress the occurrence of chipping even when a small-diameter hole having a diameter of 0.5 mm or less is drilled in a glass epoxy substrate. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of a protective film according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically showing an example of a method for drilling holes in a substrate using a protective film. [Figure 3] 10A and 10B are cross-sectional views schematically showing another example of a method for drilling holes in a substrate using a protective film. [Figure 4] FIG. 1 is a cross-sectional view schematically showing an example of drilling holes in a substrate by a conventional method. DETAILED DESCRIPTION OF THE INVENTION

[0010] ◇Protective film The protective film according to one embodiment of the present invention is a protective film for protecting a substrate when holes are drilled in the substrate, and when a peel test is conducted in which the protective film is attached to a glass epoxy substrate and then peeled from the glass epoxy substrate, the peel force between the protective film and the glass epoxy substrate is 40 mN / 25 mm or more.

[0011] The protective film of this embodiment has a peel strength of 40 mN / 25 mm or more from the glass epoxy substrate, so that when an interlayer connection hole is drilled in a multilayer circuit board such as a glass epoxy substrate, the protective film can be easily adhered to the hole drilling location of the substrate, thereby protecting the substrate. As a result, even when a small-diameter drilling hole with a diameter of 0.5 mm or less is drilled in a glass epoxy substrate, the occurrence of chipping can be suppressed.

[0012] <Peel strength between protective film and glass epoxy substrate> The peel strength between the protective film and the glass epoxy substrate is 40 mN / 25 mm or more, preferably 100 mN / 25 mm or more, more preferably 300 mN / 25 mm or more, and even more preferably 500 mN / 25 mm or more, and may be, for example, 1000 mN / 25 mm or more, 1400 mN / 25 mm or more, or 2000 mN / 25 mm or more. When the peel strength between the protective film and the glass epoxy substrate is equal to or greater than the lower limit, the protective film can be suitably attached to the substrate to be drilled, and will not peel off due to vibrations during drilling. On the other hand, there is no particular upper limit to the peel strength between the protective film and the glass epoxy substrate. For example, a protective film with a peel strength of 5000 mN / 25 mm or less between the protective film and the glass epoxy substrate can be easily achieved. In one embodiment of the protective film, the peel strength between the protective film and the glass epoxy substrate may be, for example, any one of 40 to 5000 mN / 25 mm, 500 to 4000 mN / 25 mm, 1000 to 3800 mN / 25 mm, and 1400 to 3200 mN / 25 mm, although these are just examples of the protective film.

[0013] The peel force can be measured, for example, by the following method. That is, first, a protective film with a resin film, which is configured to have a resin film on at least one side of the protective film, is cut to a width of 25 mm, and the protective film is attached to a glass epoxy substrate using a laminator heated to 60°C to prepare a test specimen. The glass epoxy substrate is fixed, and the protective film is peeled from the glass epoxy substrate at a peel rate of 300 mm / min under an environment of 23°C temperature and 50% relative humidity (RH) so that the surfaces of the protective film and the glass epoxy substrate that were in contact with each other form an angle of 180° (180° peeling). The load (peel force) during this 180° peeling is measured, and the measured values ​​over the first 5 mm length and the last 5 mm length are excluded from the effective value, and the average value of the measured values ​​over the remaining length is used as the peel force (mN / 25 mm).

[0014] In this specification, unless otherwise specified, the term "protective film" refers to a protective film that has not been intentionally cured by either heat or energy rays.

[0015] In this specification, the term "substrate device" refers to a device having a substrate with small-diameter holes formed therein. For example, a substrate device may be a semiconductor device having an electronic circuit board.

[0016] The protective film has a peel strength of 40 mN / 25 mm or more from the glass epoxy substrate and has pressure-sensitive adhesive properties. The protective film may or may not have curing properties, but preferably has both pressure-sensitive adhesive properties and curing properties. The protective film may or may not have thermosetting properties, but preferably has thermosetting properties. The protective film may have energy ray curing properties, may be non-energy ray curing properties, or may have both thermosetting properties and energy ray curing properties.

[0017] A protective film having both pressure-sensitive adhesive properties and curing properties can be attached to a substrate by gently pressing it when uncured when drilling holes in the substrate. To prevent voids during application, the protective film is preferably one that can be attached to various adherends by being softened by heating. When drilling holes in a substrate, the protective film can protect the substrate by adhering the protective film to the hole-forming portion of the substrate. When the protective film has curing properties, the protective film can be cured after adhesion to maintain adhesive properties that are more suitable for protecting the substrate when drilling holes.

[0018] In this specification, the term "thermosetting" refers to the property of being hardened by heating. As used herein, "energy rays" refers to electromagnetic waves or charged particle beams that have an energy quantum. Examples of energy rays include ultraviolet rays, radioactive rays, and electron beams. Ultraviolet rays can be irradiated using, for example, a high-pressure mercury lamp, a fusion lamp, a xenon lamp, a black light, or an LED lamp as an ultraviolet light source. Electron beams can be irradiated using those generated by an electron beam accelerator or the like. In this specification, "energy ray curable" means a property of being cured by irradiation with energy rays, and "non-energy ray curable" means a property of not being cured even when irradiated with energy rays.

[0019] When the protective film has thermosetting properties, during actual use of the protective film, the heating temperature when the protective film is thermally cured to form a cured film is preferably 100 to 200° C. The heating time during the thermal curing is preferably 0.5 to 5 hours. There are no particular limitations as long as the degree of curing of the cured film is sufficiently high, and the curing agent may be appropriately selected depending on the type of protective film.

[0020] When the protective film has energy ray curability, during actual use of the protective film, the illuminance of the energy ray during energy ray curing of the protective film is 60 to 320 mW / cm 2The amount of energy rays during the energy ray curing is preferably 100 to 1000 mJ / cm 2 It is preferable that:

[0021] <Adhesion strength between cured film and glass epoxy substrate> When the protective film is curable, the adhesive strength between the cured film obtained by curing the protective film and the glass epoxy substrate is preferably 1 N / 25 mm or more, more preferably 3 N / 25 mm or more, and even more preferably 5 N / 25 mm or more, and may be, for example, 8 N / 25 mm or more, or may be 10 N / 25 mm or more. When the adhesive strength between the cured film and the glass epoxy substrate is equal to or greater than the lower limit, better protective performance can be obtained when the cured film is attached to the substrate to be drilled, cured, and then drilled. On the other hand, there is no particular upper limit to the adhesive strength between the cured film and the glass epoxy substrate. For example, a protective film having an adhesive strength of 60 N / 25 mm or less between the cured film and the glass epoxy substrate can be easily achieved. In one embodiment of the protective film, the adhesive strength between the cured film and the glass epoxy substrate may be, for example, any one of 1 to 60 N / 25 mm, 3 to 60 N / 25 mm, 5 to 50 N / 25 mm, 8 to 50 N / 25 mm, and 10 to 40 N / 25 mm, although these are just examples of the protective film.

[0022] The adhesive strength can be measured, for example, by the following method. That is, first, a protective film with a resin film, which is configured by providing a resin film on at least one surface of the protective film, is cut to a width of 25 mm, and the protective film is attached to a glass epoxy substrate, and then the protective film is cured. When the protective film is thermosetting, the conditions for the curing treatment may be appropriately selected from the conditions for forming a cured film by thermal curing of the protective film during actual use of the protective film.When the protective film is energy ray-curable, the conditions for the curing treatment may be appropriately selected from the conditions for forming a cured film by energy ray-curing of the protective film during actual use of the protective film.

[0023] The glass epoxy substrate was then fixed in place, and the cured film was peeled from the glass epoxy substrate at a peel rate of 300 mm / min under conditions of 23°C and 50% relative humidity (RH) so that the surfaces of the cured film and the glass epoxy substrate that had been in contact with each other formed a 180° angle (180° peeling). At this time, a strong adhesive tape was attached to the cured film, and the adhesive tape was peeled from the glass epoxy substrate together with the cured film at a 180° angle. The measured values ​​for the first and last 5 mm lengths of the load were excluded from the effective value, and the average value was calculated. This was taken as the adhesive strength (N / 25 mm). If the adhesive strength between the cured film and the glass epoxy substrate was high, peeling may occur at the interface between the adhesive tape and the cured film. It was found that the adhesive strength between the cured film and the glass epoxy substrate in this case was equal to or greater than the measured adhesive strength between the adhesive tape and the cured film.

[0024] <Example of protective film> FIG. 1 is a cross-sectional view schematically illustrating an example of a protective film. In addition, the drawings used in the following explanation may show enlarged essential parts for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0025] The protective film 13 shown in Figure 1 has a first resin film 151 on one surface (sometimes referred to as the "first surface" in this specification) 13a, and a second resin film 152 on the other surface (sometimes referred to as the "second surface" in this specification) 13b opposite the first surface 13a.

[0026] The protective film 13 has a peel strength of 40 mN / 25 mm or more between itself and the glass epoxy substrate.

[0027] Although general-purpose thermoplastic resin films can be used as the first resin film 151 and the second resin film 152, it is preferable that at least one of the first resin film 151 and the second resin film 152 is a film having a glass transition temperature (Tg) of 170° C. or higher. For example, when the second resin film 152 is a film having a glass transition temperature (Tg) of 170° C. or higher, it is preferable that the protective film 13 is attached together with the second resin film 152 to the substrate to be drilled, and can be used as is for protection during drilling after heat treatment.

[0028] The protective film 13 shown in Figure 1 has a first resin film 151 and a second resin film 152 on both the first surface 13a and the second surface 13b of the protective film 13, but it may also have a form in which the second resin film 152 is provided on at least one surface of the protective film 13.

[0029] Examples of general-purpose thermoplastic resin films include amorphous films such as polyvinyl chloride film, polystyrene film, AS resin film, ABS resin film, methacrylic resin film, and polycarbonate film; and crystalline films such as polyethylene film, polypropylene film, polyolefin film, polyamide 6 film, polyamide 66 film, polyacetal film, polybutylene terephthalate film, and polyethylene terephthalate film.

[0030] Examples of films having a glass transition temperature (Tg) of 170°C or higher include amorphous films such as polyarylate films, polysulfone films, polyethersulfone films, polyamideimide films, and polyetherimide films; and crystalline films such as polyphenylene sulfide films, polyetheretherketone films, liquid crystal polymer films, and polyimide films.

[0031] Both the first resin film 151 and the second resin film 152 may be release films formed by forming a silicone-based release agent layer on one side of a polyethylene terephthalate film (by silicone treatment). When the first resin film 151 is a release film, the surface 151b of the first resin film 151 facing the protective film 13 is a release-treated surface, and when the second resin film 152 is a release film, the surface 152a of the second resin film 152 facing the protective film 13 is a release-treated surface. Such a protective film 13 is suitable for storage, for example, in a roll form. The first resin film 151 and the second resin film 152 may be the same as each other, or may be release films that require different peeling forces when peeling them from the protective film 13. By using release films with different peeling forces as the first resin film 151 and the second resin film 152, it is possible to prevent peeling defects. Peeling defects are a phenomenon in which, when peeling a release film, the protective film 13 or the cured film 131 obtained by curing the protective film 13 that should remain on the other release film ends up partially or entirely attached to the peeled release film.

[0032] In the protective film 13 shown in FIG. 1, either the first resin film 151 or the second resin film 152 is removed, and the resulting exposed surface becomes the surface to be attached to a substrate such as a glass epoxy substrate.

[0033] Figure 1 shows an example in which a resin film is provided on both sides (first side 13a, second side 13b) of protective film 13, but the resin film may be provided on only one side of protective film 13, i.e., only first side 13a or only second side 13b.

[0034] <Other components of the protective film> The protective film may consist of one layer (single layer) or two or more layers. When the protective film consists of multiple layers, these multiple layers may be the same or different from each other, and the combination of these multiple layers is not particularly limited.

[0035] In this specification, not only in the case of a protective film, "multiple layers may be the same or different from one another" means "all layers may be the same, all layers may be different, or only some layers may be the same," and further, "multiple layers are different from one another" means "at least one of the constituent materials and thicknesses of each layer is different from one another."

[0036] The thickness of the protective film is preferably 2 to 100 μm, more preferably 3 to 80 μm, and particularly preferably 5 to 50 μm. When the thickness of the protective film is equal to or greater than the lower limit, the strength of the protective film is increased and the effects obtained by using the protective film are enhanced. When the thickness of the protective film is equal to or less than the upper limit, the thickness of the protective film and its cured film can be prevented from becoming excessive. Here, "thickness of the protective film" means the thickness of the entire protective film; for example, the thickness of a protective film consisting of multiple layers means the total thickness of all layers that make up the protective film.

[0037] In this specification, the term "thickness" refers not only to protective films but also to the average thickness measured at five randomly selected points on the object, unless otherwise specified, and can be obtained using a constant pressure thickness gauge in accordance with JIS K7130.

[0038] <<Protective film-forming composition>> The protective film can be formed using a composition for forming a protective film containing the constituent materials thereof. For example, the composition for forming a protective film can be applied to the surface on which the protective film is to be formed, and then dried as necessary, to form the protective film in the desired location. The ratio of the contents of the components that do not vaporize at room temperature in the composition for forming a protective film is usually the same as the ratio of the contents of the components in the protective film.

[0039] In the protective film, the proportion of the total content of one or more components described below in the protective film relative to the total mass of the protective film does not exceed 100 mass %. Similarly, in the composition for forming a protective film, the ratio of the total content of one or more of the components contained in the composition for forming a protective film, as described below, to the total mass of the composition for forming a protective film does not exceed 100 mass %.

[0040] The composition for forming the protective film may be applied by a known method, such as a bar coater, gravure coater, roll coater, roll knife coater, or curtain coater, and examples thereof include methods using various coaters such as an air knife coater, blade coater, die coater, knife coater, screen coater, Mayer bar coater, or kiss coater.

[0041] The drying conditions for the composition for forming a protective film are not particularly limited, but when the composition for forming a protective film contains a solvent described below, it is preferable to heat-dry it. The composition for forming a protective film containing a solvent is preferably dried, for example, at 70 to 130°C for 10 seconds to 5 minutes. The components contained in the protective film and the composition for forming the protective film will be described in detail below.

[0042] The protective film-forming composition may be, for example, a composition containing a polymer component (a) and a thermosetting component (b) (sometimes abbreviated as "composition (I)" in this specification). The protective film-forming composition for forming a thermosetting protective film preferably contains a polymer component (a), a thermosetting component (b), and a curing accelerator (c). Examples of protective film-forming compositions for forming energy ray-curable protective films include compositions containing a polymer component (a) and an energy ray-curable component (g), and it is preferable that the protective film-forming composition further contains a photopolymerization initiator (h).

[0043] <Polymer component (a)> The polymer component (a) is a polymer compound that imparts film-forming properties, flexibility, etc. to the protective film. In this specification, the polymer compound also includes products of polycondensation reactions.

[0044] The polymer component (a) contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0045] Examples of the polymer component (a) include acrylic resins, urethane resins, phenoxy resins, silicone resins, saturated polyester resins, and the like. Among these, the polymer component (a) is preferably a thermoplastic resin, and more preferably an acrylic resin.

[0046] The acrylic resin in the polymer component (a) may be any known acrylic polymer. The weight-average molecular weight (Mw) of the acrylic resin is preferably 10,000 to 2,000,000, more preferably 100,000 to 1,500,000, and may be, for example, 100,000 to 1,000,000. When the weight-average molecular weight of the acrylic resin is within this range, it becomes easy to adjust the peel force between the protective film and the substrate to be drilled within a preferred range. On the other hand, when the weight-average molecular weight of the acrylic resin is equal to or greater than the lower limit, the shape stability (stability over time during storage) of the protective film is improved. When the weight-average molecular weight of the acrylic resin is equal to or less than the upper limit, the protective film can easily conform to the uneven surface of the substrate to be drilled, and the generation of voids between the protective film and the substrate to be drilled is further suppressed.

[0047] In this specification, the term "weight average molecular weight" refers to a polystyrene-equivalent value measured by gel permeation chromatography (GPC), not limited to the case of polymer component (a), unless otherwise specified.

[0048] The glass transition temperature (Tg) of the acrylic resin is preferably −60 to 70° C., more preferably −45 to 50° C., and may be, for example, −35 to 30° C. When the Tg of the acrylic resin is equal to or greater than the lower limit, excessive adhesive strength between the protective film and the resin film is suppressed, making it easier to peel the resin film after drilling. When the Tg of the acrylic resin is equal to or less than the upper limit, the peel strength between the protective film and the substrate to be drilled and the adhesive strength between the cured film obtained by curing the protective film and the substrate to be drilled are improved.

[0049] When an acrylic resin has two or more structural units, the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox equation. The Tg of the homopolymer of the monomer from which the structural units are derived can be calculated using values ​​listed in the Polymer Data Handbook, Adhesive Handbook, or Polymer Handbook.

[0050] Examples of acrylic resins include polymers of one or more (meth)acrylic acid esters; copolymers of two or more monomers selected from the above-mentioned (meth)acrylic acid esters, (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, and N-methylolacrylamide.

[0051] In this specification, the term "(meth)acrylic acid" is a concept that encompasses both "acrylic acid" and "methacrylic acid." This also applies to terms similar to (meth)acrylic acid, such as a (meth)acryloyl group.

[0052] Examples of the (meth)acrylic acid ester constituting the acrylic resin include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, and p) (meth)acrylic acid alkyl esters in which the alkyl group constituting the alkyl ester has a chain structure and has 1 to 18 carbon atoms, such as isononyl acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (palmityl (meth)acrylate), heptadecyl (meth)acrylate, and octadecyl (meth)acrylate (stearyl (meth)acrylate); (meth)acrylic acid cycloalkyl esters such as isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; (Meth)acrylic acid aralkyl esters such as benzyl (meth)acrylate; (Meth)acrylic acid cycloalkenyl esters such as (meth)acrylic acid dicyclopentenyl ester; (Meth)acrylic acid cycloalkenyloxyalkyl esters such as (meth)acrylic acid dicyclopentenyloxyethyl ester; (Meth)acrylic acid imide; glycidyl group-containing (meth)acrylic acid esters such as glycidyl (meth)acrylate; hydroxyl group-containing (meth)acrylic acid esters such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; Examples include substituted amino group-containing (meth)acrylic acid esters such as N-methylaminoethyl (meth)acrylate. Here, the term "substituted amino group" refers to a group having a structure in which one or two hydrogen atoms of an amino group are substituted with a group other than a hydrogen atom.

[0053] The acrylic resin may be, for example, a resin obtained by copolymerizing one or more monomers selected from (meth)acrylic acid, itaconic acid, vinyl acetate, acrylonitrile, styrene, N-methylolacrylamide, and the like in addition to the (meth)acrylic acid ester.

[0054] The acrylic resin may be made up of one type of monomer or two or more types of monomers, and when two or more types of monomers are used, the combination and ratio thereof can be selected arbitrarily.

[0055] The acrylic resin may or may not have a functional group capable of bonding to other compounds, such as a vinyl group, a (meth)acryloyl group, an amino group, a carboxy group, an isocyanate group, etc., in addition to the above-mentioned hydroxyl group. The functional group of the acrylic resin may bond to other compounds via a crosslinking agent (f) described below, or may bond directly to other compounds without the crosslinking agent (f).

[0056] In the present invention, as the polymer component (a), a thermoplastic resin other than an acrylic resin (hereinafter sometimes simply referred to as a "thermoplastic resin") may be used alone without using an acrylic resin, or may be used in combination with an acrylic resin. By using the thermoplastic resin, the protective film can easily conform to the uneven surface of the substrate to be drilled, and the occurrence of voids between the protective film and the substrate to be drilled may be further suppressed. By suppressing the occurrence of voids, it is also possible to enhance the effect of suppressing chipping due to drilling.

[0057] Examples of the thermoplastic resin include polyester, polyurethane, phenoxy resin, polybutene, polybutadiene, and polystyrene.

[0058] The thermoplastic resin contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0059] In the protective film, the content ratio of the polymer component (a) to the total mass of the protective film is preferably 28 mass% or less, regardless of the type of polymer component (a), and may be, for example, either 23 mass% or less or 18 mass% or less. On the other hand, the proportion is more than 0% by mass, and is preferably 8% by mass or more in that the effects obtained by using the polymer component (a) are enhanced. In one embodiment, the ratio may be, for example, any one of 8 to 28 mass %, 8 to 23 mass %, and 8 to 18 mass %, although these are just examples of the ratio.

[0060] The above content regarding the proportion of the content of polymer component (a) in the protective film relative to the total mass of the protective film is synonymous with the following: in composition (I), the proportion of the content of polymer component (a) relative to the total content of all components other than the solvent is preferably 28 mass% or less, regardless of the type of polymer component (a), and may be, for example, any one of 23 mass% or less, 18 mass% or less, and 13 mass% or less; meanwhile, the proportion is preferably greater than 0 mass% and 8 mass% or more, and in one embodiment, the proportion may be any one of 8 to 28 mass%, 8 to 23 mass%, and 8 to 18 mass%. This is based on the fact that the amount of components other than the solvent usually does not change during the process of removing the solvent from a solvent-containing composition for forming a protective film to form a protective film, and the content ratio of the components other than the solvent is the same between the composition for forming a protective film and the protective film. Therefore, hereinafter in this specification, the content of the components other than the solvent will mainly be described as the content in the protective film obtained by removing the solvent from the composition for forming a protective film.

[0061] <Thermosetting component (b)> The thermosetting component (b) has thermosetting properties and is a component for thermally curing the protective film. The thermosetting component (b) contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0062] Examples of the thermosetting component (b) include epoxy-based thermosetting resins, thermosetting polyimide resins, and unsaturated polyester resins, with epoxy-based thermosetting resins being preferred. In this specification, the term "thermosetting polyimide resin" is a general term for a polyimide precursor that forms a polyimide resin by thermal curing, and a thermosetting polyimide.

[0063] [Epoxy thermosetting resin] The epoxy thermosetting resin is composed of an epoxy resin (b1) and a thermosetting agent (b2). The epoxy thermosetting resin contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0064] (Epoxy resin (b1)) Examples of the epoxy resin (b1) include known epoxy resins, such as bifunctional or higher functional epoxy compounds, including polyfunctional epoxy resins, biphenyl compounds, bisphenol A diglycidyl ether and its hydrogenated products, orthocresol novolac epoxy resins, dicyclopentadiene epoxy resins, biphenyl epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, and phenylene skeleton epoxy resins.

[0065] The number average molecular weight of the epoxy resin (b1) is not particularly limited, but is preferably 300 to 30,000 from the viewpoints of the curability of the protective film and the strength and heat resistance of the cured film obtained by curing the protective film. The epoxy equivalent of the epoxy resin (b1) is preferably 100 to 1000 g / eq, and may be, for example, either 100 to 600 g / eq or 150 to 300 g / eq.

[0066] The epoxy resin (b1) contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0067] The composition (I) and the protective film preferably contain a dicyclopentadiene-type epoxy resin as the epoxy resin (b1). When the protective film contains such a combination of epoxy resins (b1), the substrate protection performance is improved.

[0068] When the protective film contains an epoxy resin (b1), the content ratio of the epoxy resin (b1) relative to the total mass of the protective film is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, regardless of the type of epoxy resin (b1). When this ratio is equal to or greater than the lower limit, the effect obtained by the protective film containing the epoxy resin (b1) is significantly enhanced. The content ratio of the epoxy resin (b1) relative to the total mass of the protective film is preferably 80% by mass or less, and may be, for example, either 75% by mass or less or 70% by mass or less. However, these are just examples of the above ratios.

[0069] (Thermal curing agent (b2)) The thermosetting agent (b2) is a curing agent for the epoxy resin (b1). Examples of the thermosetting agent (b2) include compounds having two or more functional groups per molecule that can react with epoxy groups. Examples of the functional groups include phenolic hydroxyl groups, alcoholic hydroxyl groups, amino groups, carboxyl groups, and anhydride groups of acid groups. Phenolic hydroxyl groups, amino groups, and anhydride groups of acid groups are preferred, and phenolic hydroxyl groups or amino groups are more preferred.

[0070] Among the heat curing agents (b2), examples of phenolic curing agents having a phenolic hydroxyl group include polyfunctional phenolic resins, biphenols, novolac-type phenolic resins, dicyclopentadiene-type phenolic resins, and aralkyl-type phenolic resins. Among the heat curing agents (b2), examples of amine-based curing agents having an amino group include dicyandiamide (DICY).

[0071] The hydroxyl group equivalent of the heat curing agent (b2) is preferably 10 to 120 g / eq, and may be, for example, either 10 to 60 g / eq or 10 to 40 g / eq.

[0072] Of the thermosetting agents (b2), for example, the number average molecular weight of resin components such as polyfunctional phenolic resins, novolac-type phenolic resins, dicyclopentadiene-type phenolic resins, and aralkyl-type phenolic resins is preferably 300 to 30,000, more preferably 400 to 10,000, and particularly preferably 500 to 3,000. Of the thermosetting agents (b2), the molecular weight of the non-resin components such as biphenol and dicyandiamide is not particularly limited, but is preferably 60 to 500, for example.

[0073] The thermosetting agent (b2) contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0074] When the thermosetting component (b) is used, the content of the thermosetting agent (b2) in the composition (I) and the protective film is preferably 0.5 to 10 parts by mass, and may be, for example, 0.5 to 5 parts by mass or 0.5 to 3 parts by mass, per 100 parts by mass of the epoxy resin (b1). When the content of the thermosetting agent (b2) is equal to or greater than the lower limit, the thermal curing of the protective film proceeds more easily. When the content of the thermosetting agent (b2) is equal to or less than the upper limit, the moisture absorption rate of the protective film is reduced, and the reliability of the package obtained using the protective film is further improved.

[0075] When a thermosetting component (b) is used, the content of the thermosetting component (b) in the composition (I) and the protective film (e.g., the total content of the epoxy resin (b1) and the thermosetting agent (b2)) is preferably 20 to 1,000 parts by mass, more preferably 100 to 1,000 parts by mass, per 100 parts by mass of the polymer component (a). For example, it may be 100 to 800 parts by mass, 100 to 500 parts by mass, 200 to 1,000 parts by mass, 300 to 1,000 parts by mass, or 400 to 800 parts by mass. When the content of the thermosetting component (b) is within this range, it becomes easier to adjust the adhesive strength after thermal curing between the cured film obtained by thermal curing the protective film and the substrate to be drilled, as described below.

[0076] <Curing accelerator (c)> The curing accelerator (c) is heat This component is used to adjust the curing speed. Preferable examples of the curing accelerator (c) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles (imidazoles in which one or more hydrogen atoms are substituted with groups other than hydrogen atoms) such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organic phosphines (phosphines in which one or more hydrogen atoms are substituted with organic groups) such as tributylphosphine, diphenylphosphine, and triphenylphosphine; tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate; and clathrate compounds in which the imidazoles are used as guest compounds.

[0077] The curing accelerator (c) contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0078] When the curing accelerator (c) is used, the content of the curing accelerator (c) in the composition (I) and the protective film is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the content of the thermosetting component (b) (e.g., the total content of the epoxy resin (b1) and the thermosetting agent (b2)). When the content of the curing accelerator (c) is equal to or greater than the lower limit, the effect of using the curing accelerator (c) is more pronounced. When the content of the curing accelerator (c) is equal to or less than the upper limit, for example, the effect of suppressing the highly polar curing accelerator (c) from migrating and segregating to the adhesive interface with the substrate to be drilled in the protective film under high temperature and high humidity conditions is enhanced, thereby further improving the reliability of the substrate device obtained using the protective film.

[0079] <Energy ray curable component (g)> The energy ray-curable component (g) is an energy ray-curable non-polymer, or an energy ray-curable oligomer or polymer (polymer) that can be considered to have been synthesized from an energy ray-curable non-polymer.

[0080] The energy ray-curable non-polymer is a component that cannot be considered as a polymer of a monomer and has energy ray-curability. The energy ray-curable non-polymer includes, for example, a compound having at least one polymerizable double bond in the molecule, and an acrylate compound having a (meth)acryloyl group is preferred.

[0081] Examples of the acrylate compounds include trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate. (meth)acrylates containing a chain aliphatic skeleton such as those listed above; (meth)acrylates containing a cyclic aliphatic skeleton such as dicyclopentanyl di(meth)acrylate and tricyclodecane dimethylol diacrylate; polyalkylene glycol (meth)acrylates such as polyethylene glycol di(meth)acrylate; oligoester (meth)acrylates; urethane (meth)acrylate oligomers; epoxy-modified (meth)acrylates; polyether (meth)acrylates other than the above polyalkylene glycol (meth)acrylates; and itaconic acid oligomers.

[0082] The weight average molecular weight of the energy ray-curable component (g) is preferably 100 to 30,000, and more preferably 300 to 10,000.

[0083] The energy ray-curable component (g) contained in the composition (I) may be one type only, or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0084] In the protective film, the content of the energy ray-curable component (g) relative to the total mass of the protective film is preferably 4 mass% or more, more preferably 6 mass% or more, more preferably 8 mass% or more, and even more preferably 9 mass% or more. When the content is equal to or more than the lower limit, the protective film can be more easily cured with energy rays. On the other hand, the above ratio is advantageous in that excessive use of the energy ray-curable component (g) is suppressed. 20It is preferably % by mass or less. In one embodiment, the ratio may be, for example, any one of 4 to 20 mass %, 6 to 15 mass %, 8 to 12 mass %, and 9 to 10 mass %, although these are just examples of the ratio.

[0085] <Photopolymerization initiator (h)> The composition (I) and the protective film contain the photopolymerization initiator (h), which allows the polymerization reaction of the energy ray-curable component (g) to proceed efficiently.

[0086] Examples of the photopolymerization initiator (h) include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, and benzoin dimethyl ketal; acetophenone compounds such as acetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, and 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one; bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2,4,6-trimethylbenzoyl Examples of the compound include acylphosphine oxide compounds such as diphenylphosphine oxide; sulfide compounds such as benzyl phenyl sulfide and tetramethylthiuram monosulfide; α-ketol compounds such as 1-hydroxycyclohexyl phenyl ketone; azo compounds such as azobisisobutyronitrile; titanocene compounds such as titanocene; thioxanthone compounds such as thioxanthone; peroxide compounds; diketone compounds such as diacetyl; benzyl; dibenzyl; benzophenone; 2,4-diethylthioxanthone; 1,2-diphenylmethane; 2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone; and quinone compounds such as 1-chloroanthraquinone and 2-chloroanthraquinone. Examples of the photopolymerization initiator (h) include photosensitizers such as amines.

[0087] The photopolymerization initiator (h) contained in the composition (I) and the protective film may be one type or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0088] When the photopolymerization initiator (h) is used, the content of the photopolymerization initiator (h) in the composition (I) and the protective film is preferably 0.1 to 12 parts by mass, more preferably 0.5 to 9 parts by mass, and particularly preferably 1 to 6 parts by mass, per 100 parts by mass of the energy ray-curable component (g).

[0089] Other ingredients The composition for forming a protective film may or may not contain other components that do not fall under any of the polymer component (a), the thermosetting component (b), the curing accelerator (c), the energy ray-curable component (g), and the photopolymerization initiator (h). Examples of the other components include a filler (d), a coupling agent (e), a crosslinking agent (f), a colorant (i), and a general-purpose additive (j). The other components contained in the composition (I) and the protective film, such as the filler (d), coupling agent (e), crosslinking agent (f), colorant (i), and general-purpose additive (j), may each be one type only or two or more types, and if two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

[0090] <Filling material (d)> By including the filler (d), the protective film can easily adjust its thermal expansion coefficient, and this thermal expansion coefficient can be optimized for the object to which the protective film is attached.

[0091] The filler (d) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler. Preferred inorganic fillers include, for example, powders of silica, alumina, talc, calcium carbonate, titanium white, red iron oxide, silicon carbide, boron nitride, etc.; beads obtained by spheronizing these inorganic fillers; surface-modified products of these inorganic fillers; single-crystal fibers of these inorganic fillers; glass fibers, etc.

[0092] The average particle size of the filler (d) is not particularly limited, but is preferably 10 nm to 5 μm. When the average particle size of the filler (d) is in this range, the effect of using the filler (d) can be sufficiently obtained, and the storage stability of the protective film can be further improved.

[0093] In this specification, unless otherwise specified, the term "average particle size" refers to the particle size at 50% of the integrated value in the particle size distribution curve obtained by the laser diffraction scattering method (D 50 ) value.

[0094] In the protective film, the content of the filler (d) relative to the total mass of the protective film is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, still more preferably 10% by mass or less, still more preferably 5% by mass or less, and particularly preferably 3% by mass or less. As will be described later, when a protective film or a cured film obtained by curing the protective film is used to drill a substrate through the protective film or the cured film, having the content in this range can reduce the load on the drill. On the other hand, the proportion is 0% by mass or more. In terms of reducing the load on the drill, it is most preferable that the proportion is 0 mass %, that is, the protective film does not contain the filler (d).

[0095] <Coupling agent (e)> The protective film contains a coupling agent (e), which improves the peel strength between the protective film and the substrate to be drilled, and the adhesive strength between the cured film obtained by curing the protective film and the substrate to be drilled. Furthermore, the protective film contains a coupling agent (e), which improves the water resistance of the protective film and the cured film obtained by curing the protective film without impairing the heat resistance. The coupling agent (e) has a functional group that can react with an inorganic compound or an organic compound.

[0096] The coupling agent (e) is preferably a compound having a functional group capable of reacting with a functional group (e.g., a second functional group) possessed by the polymer component (a), the thermosetting component (b), etc., and is more preferably a silane coupling agent.

[0097] Preferred examples of the silane coupling agent include 3-glycidyloxypropyltrimethoxysilane (also referred to as 3-glycidoxypropyltrimethoxysilane; the same applies to other compounds hereinafter), 3-glycidyloxypropylmethyldiethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxymethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, Examples of the organosiloxane include silane, 3-(2-aminoethylamino)propylmethyldiethoxysilane, 3-(phenylamino)propyltrimethoxysilane, 3-anilinopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, imidazole silane, and oligomeric or polymeric organosiloxanes.

[0098] When a coupling agent (e) is used, the content of the coupling agent (e) in the composition (I) and the protective film is preferably 0.03 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and may be, for example, 0.1 to 2 parts by mass, per 100 parts by mass of the total content of the polymer component (a) and the thermosetting component (b). When the content of the coupling agent (e) is equal to or greater than the lower limit, the effects of using the coupling agent (e), such as improved dispersibility of the filler (d) in the resin and improved adhesive strength between the cured film obtained by curing the protective film and the substrate to be drilled, are more significantly achieved. When the content of the coupling agent (e) is equal to or less than the upper limit, outgassing is further suppressed.

[0099] <Crosslinking agent (f)> When the polymer component (a) is a polymer having a functional group such as a vinyl group, (meth)acryloyl group, amino group, hydroxyl group, carboxyl group, or isocyanate group that can bond with other compounds, such as the acrylic resin described above, the composition (I) and the protective film may contain a crosslinking agent (f) for crosslinking the functional group with other compounds. Crosslinking using the crosslinking agent (f) allows the initial adhesive strength and cohesive strength of the protective film to be adjusted.

[0100] Examples of the crosslinking agent (f) include organic polyvalent isocyanate compounds, organic polyvalent imine compounds, metal chelate crosslinking agents (crosslinking agents having a metal chelate structure), and aziridine crosslinking agents (crosslinking agents having an aziridinyl group).

[0101] In the composition (I) and the protective film, the content of the crosslinking agent (f) is preferably 6 parts by mass or less, more preferably 3 parts by mass or less, per 100 parts by mass of the content of the polymer component (a), and is 0 parts by mass or more.

[0102] <Colorant (i)> The protective film preferably contains a colorant (i). By containing the colorant (i) in the protective film, it is possible to confirm whether the protective film has been left on the surface, and thus it is possible to prevent forgetting to leave the protective film on the surface. The colorant (i) is a component that can adjust the transmittance of light of various wavelengths in the protective film and in the cured film obtained by curing the protective film. Examples of the colorant (i) include known colorants such as inorganic pigments, organic pigments, organic dyes, etc. Black pigments are preferred.

[0103] When colorant (i) is used, the content of colorant (i) in the protective film relative to the total mass of the protective film is preferably 0.01 to 20 mass %, regardless of the type of colorant (i). When this content is equal to or greater than the lower limit, the effect of using colorant (i) is more pronounced. When this content is equal to or less than the upper limit, excessive use of colorant (i) is suppressed.

[0104] <General-purpose additives (j)> The general-purpose additive (j) may be a known one and may be selected arbitrarily depending on the purpose, and is not particularly limited. Preferred general-purpose additives (j) include, for example, plasticizers, antistatic agents, antioxidants, gettering agents, antifoaming agents, and leveling agents.

[0105] The content of the general-purpose additive (i) in the composition (I) and the protective film is not particularly limited and can be selected appropriately depending on, for example, the type of the general-purpose additive (i).

[0106] <Solvent> Composition (I) preferably further contains a solvent, which improves the handleability of composition (I).

[0107] In this specification, unless otherwise specified, the term "solvent" is used to refer to a concept that includes not only a substance that dissolves a target component, but also a dispersion medium that disperses the target component.

[0108] The solvent is not particularly limited, but preferred examples include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; and ethers such as tetrahydrofuran. The composition (I) may contain only one type of solvent, or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

[0109] The solvent contained in composition (I) is preferably methyl ethyl ketone or the like, since this allows the components contained in composition (I) to be mixed more uniformly.

[0110] The content of the solvent in the composition (I) is not particularly limited, and may be selected appropriately depending on, for example, the types of components other than the solvent.

[0111] ◇How to use the protective film The protective film according to the above embodiment can be used to drill holes in a substrate. FIG. 2 is a cross-sectional view that schematically shows an example of a method for drilling holes in a substrate 10 using a resin film-attached protective film that includes a second resin film 152 on one surface of a protective film 13. As shown in FIG. First, a protective film 13 is attached to one surface of the substrate 10 to obtain a laminate consisting of the second resin film 152 / protective film 13 / substrate 10. Next, a protective film 13 is attached to the other surface of the substrate 10 to obtain a laminate (1) consisting of the second resin film 152 / protective film 13 / substrate 10 / protective film 13 / second resin film 152. The protective film 13 of the laminate (1) is cured to obtain a laminate (2) consisting of the second resin film 152 / cured film 131 / substrate 10 / cured film 131 / second resin film 152. Thereafter, a small-diameter drilled hole 12 can be drilled in the laminate (2) using a drill, and chipping can be prevented even when drilling a small-diameter drilled hole 12 with a diameter of 0.5 mm or less.

[0112] The substrate 10 may be either a rigid substrate or a flexible substrate, but rigid substrates such as glass epoxy substrates and paper phenolic substrates are preferably used. The small-diameter processing holes 12 can be drilled in a circuit board on which electronic circuits have been formed on one or both sides, and can also be drilled in a board before the electronic circuits have been formed.

[0113] FIG. 2 shows an example in which a small-diameter drilled hole 12 is drilled in a laminate (2) consisting of the second resin film 152 / cured film 131 / substrate 10 / cured film 131 / second resin film 152. However, a small-diameter drilled hole 12 can also be drilled in a laminate (1) consisting of the second resin film 152 / protective film 13 / substrate 10 / protective film 13 / second resin film 152. Even when drilling a small-diameter drilled hole 12 having a diameter of 0.5 mm or less, chipping can be suppressed. In this case, a general-purpose thermoplastic resin film can be used as the second resin film 152. After drilling a small-diameter drilled hole 12 in the laminate (1), a curing treatment may be performed as necessary. Alternatively, when the second resin film 152 has both thermosetting and energy ray curing properties, the second resin film 152 may be subjected to a thermosetting treatment to form a laminate (2), and a small diameter machining hole 12 may be drilled in the laminate (2) using a drill, followed by an energy ray curing treatment; alternatively, the second resin film 152 may be subjected to an energy ray curing treatment to form a laminate (2), and a small diameter hole may be drilled in the laminate (2), followed by a thermosetting treatment.

[0114] Figure 2 shows an example of drilling small diameter holes 12 in one substrate 10 using a drill, but it is also possible to drill small diameter holes 12 in multiple laminates (2) or laminates (1) at once using a drill, and even when drilling small diameter holes 12 with a diameter of 0.5 mm or less, the occurrence of chipping can be suppressed.

[0115] FIG. 3 is a cross-sectional view schematically showing another example of a method for drilling holes in the substrate 10. In FIG. First, a protective film 13 is attached to one surface of the substrate 10 to obtain a laminate (3) consisting of a second resin film 152 / protective film 13 / substrate 10. Next, the protective film 13 of the laminate (3) is cured to obtain a laminate (4) consisting of a second resin film 152 / cured film 131 / substrate 10. Thereafter, a small diameter drilled hole 12 can be drilled from the side of the second resin film 152 and the cured film 131, and even when drilling a small diameter drilled hole 12 with a diameter of 0.5 mm or less, the occurrence of chipping can be suppressed.

[0116] Figure 3 shows an example in which a small diameter machining hole 12 is drilled using a drill from the side of the second resin film 152 and the cured film 131 in a laminate (4) consisting of a second resin film 152 / cured film 131 / substrate 10, but it is also possible to drill a small diameter machining hole 12 from the side of the substrate 10 of the laminate (4), and even when drilling a small diameter machining hole 12 with a diameter of 0.5 mm or less, the occurrence of chipping can be further suppressed. Furthermore, small diameter holes 12 can be drilled in the laminate (3) consisting of the second resin film 152 / protective film 13 / substrate 10 from the side of the second resin film 152 and the protective film 13, and chipping can be suppressed even when small diameter holes 12 with a diameter of 0.5 mm or less are drilled. Conversely, small diameter holes 12 can be drilled from the side of the substrate 10 of the laminate (3), and chipping can be further suppressed even when small diameter holes 12 with a diameter of 0.5 mm or less are drilled.

[0117] Figure 3 shows an example of drilling small diameter holes 12 in one substrate 10 using a drill, but it is also possible to drill small diameter holes 12 in multiple laminates (4) or laminates (3) at once using a drill, and even when drilling small diameter holes 12 with a diameter of 0.5 mm or less, the occurrence of chipping can be suppressed. [Example]

[0118] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the examples shown below.

[0119] <<Raw materials for resin manufacturing>> The full names of the raw materials for producing the resins, which are abbreviated in the examples and comparative examples, are shown below. MA: methyl acrylate HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate GMA: Glycidyl methacrylate

[0120] <<Raw materials for manufacturing the protective film-forming composition>> The raw materials used in the production of the protective film-forming composition are shown below. [Polymer component (a)] (a)-1: Acrylic resin (weight average molecular weight: 400,000, glass transition temperature: −1° C.) obtained by copolymerizing BA (10 parts by mass), MA (70 parts by mass), GMA (5 parts by mass), and HEA (15 parts by mass). [Epoxy resin (b1)] (b1)-1: A mixture of liquid bisphenol F epoxy resin and acrylic rubber particles (Nippon Shokubai Co., Ltd.'s "Acryset (registered trademark) BPF307", epoxy equivalent 190 g / eq) (b1)-2: Solid BisA epoxy resin ("jER1055" manufactured by Mitsubishi Chemical Corporation, softening point 93°C, epoxy equivalent: 800-900) (b1)-3: Dicyclopentadiene-type epoxy resin (DIC "HP7200", softening point 60°C, epoxy equivalent 258g / eq) [Thermal curing agent (b2)] (b2)-1: Dicyandiamide (Mitsubishi Chemical Corporation "DICY7", average particle size 7 μm, softening point 207-210°C) [Curing accelerator (c)] (c)-1: 2-phenyl-4,5-dihydroxymethylimidazole ("Curezol (registered trademark) 2PHZ-PW" manufactured by Shikoku Chemicals Corporation) [Coupling agent (e)] (e)-1: Methyl group and methoxy group-containing oligomeric silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "X-41-1056", epoxy equivalent 280 g / eq) [Crosslinking agent (f)] (f)-1: TDI-based isocyanate crosslinking agent (Toyochem Co., Ltd., BHS8515) [Energy ray curable component (g)] (g)-1: A mixture of dipentaerythritol hexaacrylate (a hexafunctional UV-curable compound, molecular weight 578) and dipentaerythritol pentaacrylate (a pentafunctional UV-curable compound, molecular weight 525) ("DPHA" manufactured by Nippon Kayaku Co., Ltd.) [Photopolymerization initiator (h)] (h)-1: 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one ("IRGACURE (registered trademark) 127" manufactured by BASF Japan Ltd.) [Colorant (i)] (i)-1: Black pigment (6377 Black, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)

[0121] [Example 1] <<Protective film manufacturing>> <Production of protective film-forming composition> Polymer component (a)-1 (15 parts by mass), epoxy resin (b1)-1 (25 parts by mass), epoxy resin (b1)-2 (30 parts by mass), epoxy resin (b1)-3 (6.5 parts by mass), heat curing agent (b2)-1 (1.0 part by mass), curing accelerator (c)-1 (1.0 part by mass), coupling agent (e)-1 (1.0 part by mass), crosslinker (f)-1 (0.2 part by mass), energy ray curable component (g)-1 (10 parts by mass), photopolymerization initiator (h)-1 (0.3 parts by mass), and colorant (i)-1 (10 parts by mass) were dissolved or dispersed in methyl ethyl ketone and stirred at 23°C to produce a heat-curable and energy ray-curable protective film-forming composition having a total concentration of all components other than the solvent of 50% by mass. Note that the amounts of all components other than the solvent shown here are the amounts of the target product excluding the solvent.

[0122] <Protective film manufacturing> A release film (second release film, "SP-PET502150" manufactured by Lintec Corporation, thickness 50 μm) made of polyethylene terephthalate film, one side of which had been treated for release by silicone treatment, was used. The protective film-forming composition obtained above was applied to the release-treated surface, and dried at 100°C for 1 minute to produce a protective film having both energy ray curability and heat curability, with a thickness of 20 μm. Hereinafter in this specification, this protective film may be referred to as "protective film (1)". Furthermore, a protective film with a release film was produced by bonding the release-treated surface of a separate release film (first release film, "SP-PET3801" manufactured by Lintec Corporation, thickness 38 μm) to the exposed surface of the obtained protective film (protective film (1)) that did not have the second release film, thereby producing a protective film with a release film comprising a protective film, a first release film provided on one side of the protective film, and a second release film provided on the other side of the protective film.

[0123] <<Evaluation of protective films>> <Evaluation of chipping after drilling process> The first release film (light release) was peeled off from the protective film with a release film, and the protective film (1) was attached to one surface of the glass epoxy substrate with a roll heated to 60°C. A protective film (1) was similarly attached to the other side of the glass epoxy substrate to obtain a laminate (1) having a laminate structure of second release film / protective film (1) / glass epoxy substrate / protective film (1) / second release film. The protective film was then thermally cured by heating in an oven at 160°C for 60 minutes to form a cured film. This resulted in a laminate (2) having a laminate structure of second release film / cured film / glass epoxy substrate / cured film / second release film. Thereafter, using a drilling machine (ND-1A221) manufactured by Via Mechanics, 36 holes were drilled in the laminate (2) in a 6-row, 6-column arrangement in a 30 mm x 30 mm square using a drill with a diameter of 0.4 mm and a rotation speed of 100,000 rpm. After the hole drilling process, the laminate (2) having a laminated structure of second release film / cured film / glass epoxy substrate / cured film / second release film was left in the state, and the number of chipped holes in the substrate at the entrance and exit of the drilled holes was visually counted. As a result, no chipping was confirmed on either the entrance side or the exit side of the drilled holes.

[0124] <Measurement of peel strength before curing> The first release film (light release) was peeled off, and the protective film (1) was attached to a glass epoxy substrate with a roll heated to 60° C., and the second release film (heavy release) was peeled off. The glass epoxy substrate was fixed, and a strong adhesive tape was applied to the exposed protective film (1). The peel force when the adhesive tape and the protective film were peeled off from the glass epoxy substrate at a peel angle of 180° and a peel speed of 300 mm / min was measured and found to be 3000 mN / 25 mm. In the evaluation of the protective film of Example 1, a glass cloth-epoxy resin-impregnated double-sided copper-clad laminate (manufactured by Hitachi Chemical Co., Ltd., product name "MCL-E-679") was used as the glass epoxy substrate. The same glass epoxy substrate was used in Examples 2 to 4 and Comparative Example 1.

[0125] <Adhesive strength after curing> As in the measurement of the pre-cure peel strength, the first release film (light release) was peeled off, and the protective film (1) was attached to a glass epoxy substrate. Then, with the second release film still attached, the protective film (1) was subjected to a heat curing treatment at 160 °C for 60 minutes. The glass epoxy substrate was then fixed, and a strong adhesive tape was attached to the heat-cured protective film (cured film). The adhesive tape was peeled from the glass epoxy substrate together with the cured film at a 180 ° angle at a peeling rate of 300 mm / min. The post-cure adhesive strength was measured. Peeling occurred at the interface between the adhesive tape and the cured film, and the measured adhesive strength between the adhesive tape and the cured film was 5 N / 25 mm. It can be seen that the adhesive strength between the cured film and the glass epoxy substrate was 5 N / 25 mm or more.

[0126] [Example 2] <Evaluation of chipping after drilling process> Using the same protective film (1) as in Example 1, the first release film (light release) was peeled off, and the protective film (1) was attached to one side of a glass epoxy substrate using a roll heated to 60°C, thereby obtaining a laminate (3) having a laminated structure of second release film / protective film (1) / glass epoxy substrate. The protective film was thermally cured into a cured film by heating in an oven at 160°C for 60 minutes, thereby obtaining a laminate (4) having a laminate structure of second release film / cured film / glass epoxy substrate. Thereafter, using a drilling machine (ND-1A221) manufactured by Via Mechanics, 36 holes were drilled in the laminate (4) from the side of the second release film, using a drill with a diameter of 0.4 mm and a rotation speed of 100,000 rpm, in an arrangement of 6 rows and 6 columns in a square of 30 mm x 30 mm. After the hole drilling process, the laminate (4) having the laminated structure of second release film / cured film / glass epoxy substrate was left in the state, and the number of chipped holes in the substrate at the entrance and exit of the drilled holes was visually counted. As a result, no chipping was found on the entrance side of the drilled holes, but three chips were found on the exit side of the drilled holes.

[0127] [Example 3] <Evaluation of chipping after drilling process> Using the same protective film (1) as in Example 1, the first release film (light release) was peeled off, and the protective film (1) was attached to one side of a glass epoxy substrate using a roll heated to 60°C, thereby obtaining a laminate (5) having a laminated structure of glass epoxy substrate / protective film (1) / second release film. The protective film was thermally cured into a cured film by heating in an oven at 160°C for 60 minutes, thereby obtaining a laminate (6) having a laminate structure of glass epoxy substrate / cured film / second release film. Thereafter, using a drilling machine (ND-1A221) manufactured by Via Mechanics, 36 holes were drilled in the laminate (6) from the glass epoxy substrate side using a drill with a diameter of 0.4 mm at a rotation speed of 100,000 rpm in a 30 mm x 30 mm square arrangement of 6 rows and 6 columns. After drilling, the laminate (6) having a laminated structure of glass epoxy substrate / cured film / second release film was left in its original state, and the number of chipped holes in the substrate at the entrance and exit of the drilled holes was visually counted. As a result, one chip was found at the entrance side of the drilled hole. No chipping was found at the exit side of the drilled hole.

[0128] [Example 4] <Evaluation of chipping after drilling process> As in Example 1, two laminates (2) each having a laminate structure of second release film / cured film / glass epoxy substrate / cured film / second release film were prepared. Then, with the two laminates (2) stacked on top of each other, a drilling machine (ND-1A221) manufactured by Via Mechanics was used to drill 36 holes in each of the 30 mm x 30 mm square laminates (2) in an arrangement of 6 rows and 6 columns, using a drill with a diameter of 0.4 mm and a rotation speed of 100,000 rpm. After the holes were drilled, the number of chipped holes in the substrate at the entrance and exit of each drilled hole was visually counted for the first and second laminates (2) having a laminated structure of second release film / cured film / glass epoxy substrate / cured film / second release film. As a result, no chipping was found on either the entrance or exit side of the drilled hole in either the first laminate (2) or the second laminate (2).

[0129] [Comparative Example 1] <Evaluation of chipping after drilling process> Using a drilling machine (ND-1A221) manufactured by Via Mechanics, 36 holes were drilled in the glass epoxy board under the same conditions. After drilling, the number of chipped holes on the glass epoxy board was visually counted at the entrance and exit of the drilled holes. As a result, 3 chips were found on the entrance side of the drilled holes, and 10 chips were found on the exit side of the drilled holes.

[0130] As is clear from the above results, in Example 1, when the protective film was attached to the drill entrance side and the drill exit side of the glass epoxy substrate and drilling was performed, chipping of the substrate was prevented on both the drill entrance side and the drill exit side, even when a small diameter drill hole with a diameter of 0.5 mm or less was drilled using a drill.

[0131] In Example 2, a protective film was attached to the drill entrance side of the glass epoxy substrate and then drilling was performed. This prevented chipping of the substrate on the drill entrance side and suppressed chipping of the substrate on the drill exit side, even when a small-diameter drill hole with a diameter of 0.5 mm or less was drilled using a drill.

[0132] In Example 3, a protective film was attached to the drill exit side of the glass epoxy substrate and then drilled. This prevented chipping of the substrate on the drill exit side, and also suppressed chipping of the substrate on the drill entrance side, even when drilling small holes with a diameter of 0.5 mm or less.

[0133] As is clear from the above results, in Example 4, when protective films were attached to the drill entrance and exit sides of glass epoxy substrates and multiple substrates were drilled simultaneously, chipping of the substrates was prevented on both the drill entrance and exit sides for all substrates, even when small-diameter holes with a diameter of 0.5 mm or less were drilled using a drill.

[0134] In contrast, in Comparative Example 1, drilling was performed without the protection of a protective film, and when a small-diameter drilling hole with a diameter of 0.5 mm or less was drilled using a drill, chipping of the substrate occurred both at the drill entrance side and the drill exit side. [Industrial Applicability]

[0135] The present invention can be used in drilling a substrate device. [Explanation of symbols]

[0136] 13 Protective film, 13a First surface of protective film, 131 Hardened film, 151 First resin film, 152 Second resin film, 9 Drill, 10 Substrate, 12 Drilled hole

Claims

1. There is a protective film to protect the board when drilling holes in the board. A protective film in which, when the protective film is attached to a glass epoxy substrate and then a peel test is conducted in which the protective film is peeled from the glass epoxy substrate, the peel strength between the protective film and the glass epoxy substrate is 40 mN / 25 mm or more.

2. The protective film according to claim 1 , which is thermosetting.

3. The protective film according to claim 1 or 2, wherein the content of the filler (d) relative to the total mass of the protective film is 30 mass % or less.

4. 3. The protective film according to claim 1, which is a protective film for protecting a substrate when a small-diameter hole having a diameter of 0.5 mm or less is drilled in the substrate using a drill.

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