Protective film forming sheet and method for producing the same

Abstract

The present invention provides a protective film-forming sheet and a method for producing the same, which can sufficiently suppress waste removal defects even when the kerf width during punching is narrow. The protective film-forming sheet is a long sheet comprising a protective film-forming film and a first release film provided on one surface of the protective film-forming film. The protective film-forming sheet is characterized in that the adhesion strength of the two protective film-forming films after bonding them together at 23°C under a load of 2 kgf for 2 minutes is 19 N / 25 mm or less.

Description

Technical Field

[0001] The present invention relates to a protective film-forming sheet and a method for producing the same. In particular, the present invention relates to a protective film-forming sheet having a protective film suitable for protecting a workpiece such as a semiconductor wafer or a processed product such as a semiconductor chip obtained by processing the workpiece, and a method for producing the protective film-forming sheet. Background Art

[0002] In recent years, semiconductor devices have been manufactured using a mounting method known as flip-chip bonding. In this method, when mounting a semiconductor chip with a circuit surface formed with protruding electrodes such as bumps, the circuit surface of the semiconductor chip is flipped over (face down) and bonded to a chip mounting portion. As a result, the semiconductor device has a structure where the back side of the semiconductor chip, where no circuitry is formed, is exposed.

[0003] Therefore, in order to protect the semiconductor chip from impacts such as during transportation, a hard protective film formed of an organic material is often formed on the back side of the semiconductor chip. In order to form this protective film, an uncured resin film (hereinafter referred to as a "protective film forming film") is used as its precursor. The protective film forming film is attached to the back of the semiconductor wafer and is cut together with the wafer to form a chip. By curing the protective film forming film, a chip with a protective film on the back can be obtained.

[0004] As a product form of a protective film forming film, the following is known: Figure 1 As shown in FIG. 1 , a protective film forming sheet 10 having a double-layer structure in which a protective film forming film 11 is laminated in a releasable manner on a first release film 12, or as shown in FIG. Figure 3 The protective film forming sheet 20 is a three-layer structure in which a protective film forming film 11 is sandwiched between two peeling films (12, 13). In addition, the protective film forming sheet is long and is wound into a roll for storage and transportation. Sometimes, the protective film forming sheet is pre-punched into a shape roughly the same as the workpiece (a general term for adherends such as semiconductor wafers) and attached to the workpiece. The punched protective film forming sheet is formed by stacking the protective film forming film 16 punched into a predetermined closed shape on the first peeling film 12 ( Figure 2 ), or sandwiched between two release films (12, 13) ( Figure 4 ).

[0005] The punched protective film-forming sheet is manufactured by punching a protective film-forming film into a predetermined closed shape using a die, and is used by removing an unnecessary portion 17 around the punched protective film-forming film 16. In the case of a two-layer protective film-forming sheet consisting of a protective film-forming film 11 and a first release film 12, the cutout 14 is made by completely punching the protective film-forming film 11 into the predetermined closed shape while not completely punching the first release film 12. The protective film-forming film 16 in the predetermined closed shape remains on the first release film 12, and the unnecessary portion 17 around the periphery is removed. When a protective film forming sheet has a three-layer structure in which a protective film forming film 11 is clamped between two peeling films (12, 13), an incision 14 is made in such a way that the protective film forming film 11 and the second peeling film 13 on one side are completely punched out into a prescribed closed shape and the first peeling film 12 on the other side is not completely punched out, and the protective film forming film 16 of the prescribed closed shape remains on the first peeling film 12, and the useless parts 17 and the second peeling film 13 on the periphery are removed.

[0006] The following is further explained in detail by taking the case of a double-layer protective film forming sheet as an example. Figure 5 As shown, a protective film-forming sheet 10 composed of a protective film-forming film 11 and a first release film 12 is punched out by cutting slits 14 so that the protective film-forming film 11 is completely punched into a predetermined closed shape while the first release film 12 is not completely punched out. This process is referred to as a "punching process."

[0007] Then, in order to attach the punched protective film forming sheet to a workpiece, an unnecessary portion 17 ( Figure 6 This step is called a "waste removal step." As a result, a laminate having a protective film-forming film 16 punched out into a predetermined closed shape on the first release film 12 and capable of being attached to a workpiece is obtained.

[0008] In the case of a three-layer protective film forming sheet, it is the same as the case of a two-layer protective film forming sheet, except that another peeling film 13 (second peeling film 13) is provided on the protective film forming film 11 in the punching process, and the second peeling film 13 is also completely punched into a specified closed shape, and the second peeling film 13 is removed in the waste removal process.

[0009] The protective film-forming sheet is required to be able to perform the punching process stably (operational stability). In particular, the waste removal process, which removes unnecessary portions after punching the protective film-forming sheet, requires operational stability. More specifically, during the waste removal process, it is required that the protective film-forming sheet 16 that should remain, not accidentally peel off from the first release film 12 along with the unnecessary portions 17 (hereinafter referred to as "waste removal failure"), which should not occur.

[0010] In order to solve the above-mentioned problem, for example, Patent Document 1 proposes controlling the peeling force between a release film and a protective film-forming film within a predetermined range.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: International Publication No. WO2017 / 145735 Summary of the Invention

[0014] Technical Problems to be Solved by the Invention

[0015] If scrap removal failure occurs, the production line must be stopped and defective products must be discarded, which reduces product productivity and increases costs. Therefore, it is required to further suppress scrap removal failure.

[0016] The inventors of the present invention have further diligently studied the causes of poor waste material removal and have obtained the following findings.

[0017] After the punching process and before the waste material removal process, the protective film forming sheet 10 is passed through a plurality of rollers such as guide rollers for the purpose of controlling the tension of the protective film forming sheet. Figure 7 As shown, the protective film-forming sheet 10 may be bent so that the upper side of the cutout 14 (the surface on the side where the die enters) faces the roller 19. As a result of the bending, the width of the cutout 14 becomes narrower, particularly in the cutout portion that is substantially parallel to the short side of the sheet 10. At the same time, the protective film-forming film 16 is squeezed and slightly deformed. This may partly cause the adjacent protective film-forming film 16 to come into contact with and adhere to the useless portion 17.

[0018] After passing through the roller 19, the attachment portion of the protective film-forming film 16 and the unnecessary portion 17 often separates again, but sometimes remains attached without separation. If waste material removal is performed while the protective film-forming film 16 and the unnecessary portion 17 are still attached, the protective film-forming film 16 that should remain on the first release film 12 may be accidentally peeled off from the first release film 12 along with the unnecessary portion 17 that should be removed, resulting in poor waste material removal.

[0019] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a protective film-forming sheet and a method for producing the same, which can sufficiently suppress defective waste removal even when the slit width during punching is narrow.

[0020] Technical means to solve technical problems

[0021] The solutions of the present invention are as follows.

[0022] (1) A sheet for forming a protective film, which is a long sheet and comprises a protective film-forming film and a first release film provided on one surface of the protective film-forming film, wherein:

[0023] The adhesion strength after two protective film-forming films were attached to each other at 23° C. with a load of 2 kgf for 2 minutes was 19 N / 25 mm or less.

[0024] (2) The protective film forming sheet according to (1), wherein the surface elastic modulus of the surface of the first release film in contact with the protective film forming film is 17 MPa or less.

[0025] (3) The protective film forming sheet according to (1) or (2), wherein a notch is formed on the protective film forming sheet so that a portion of the protective film forming sheet has a predetermined closed shape when the protective film forming sheet is viewed from above.

[0026] The incision penetrates the protective-film-forming film in the thickness direction of the protective-film-forming sheet and reaches a portion of the first release film.

[0027] (4) The protective-film-forming sheet according to (3), wherein a width of the cut at the interface between the protective-film-forming film and the first release film is 8 μm or more.

[0028] (5) A method for producing a punched protective film-forming sheet, comprising the step of forming a notch so that a portion of the protective film-forming sheet according to (1) or (2) has a predetermined closed shape.

[0029] The incision penetrates the protective-film-forming film in the thickness direction of the protective-film-forming sheet and reaches a portion of the first release film.

[0030] (6) The method for producing a punched protective film-forming sheet according to (5), wherein a width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more.

[0031] Effects of the Invention

[0032] According to the present invention, a protective film-forming sheet and a method for producing the same can be provided, which can sufficiently suppress defects in scrap removal even when the slit width during punching is narrow. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic cross-sectional view of a protective film forming sheet according to an embodiment

[0034] Figure 2 It is a schematic cross-sectional view showing a state in which the protective film forming sheet according to the embodiment is punched.

[0035] Figure 3 This is a schematic cross-sectional view of a protective film-forming sheet according to another embodiment.

[0036] Figure 4 This is a schematic cross-sectional view showing a state in which a protective film-forming sheet according to another embodiment is punched.

[0037] Figure 5 This is a schematic perspective view of the protective film forming sheet after the punching process.

[0038] Figure 6 A schematic perspective view showing the waste removal process.

[0039] Figure 7 It is a cross-sectional view showing a state where the protective film-forming sheet passes through a roller after the punching process.

[0040] Figure 8 This is a schematic cross-sectional view of an example of a chip having a protective film obtained by converting the protective film-forming film of this embodiment into a protective film.

[0041] Figure 9 It is a schematic cross-sectional view for explaining the step of attaching the protective film forming sheet of this embodiment to a wafer.

[0042] Figure 10 A schematic cross-sectional view illustrating a singulation process of a wafer with a protective film.

[0043] Figure 11 A schematic cross-sectional view illustrating the process of placing a chip with a protective film on a substrate.

[0044] Description of Reference Numerals

[0045] 10: Sheet for forming a protective film (this embodiment); 11: Protective film-forming film; 12: First peeling film; 13: Second peeling film; 14: Incision; 16: Punched protective film-forming film; 17: Useless portion; 19: Roller; 20: Sheet for forming a protective film (another embodiment); 21: Wafer; 22: Cutting sheet; 30: Chip with protective film; 31: Chip; 32: Protective film; 33: Protruding electrode; 50: Substrate. DETAILED DESCRIPTION

[0046] First, main terms used in this specification are explained.

[0047] The workpiece is a plate-like object to be processed and attached to the protective film-forming film of this embodiment. Examples of the workpiece include wafers and panels. Specifically, semiconductor wafers and semiconductor panels can be used. Examples of processed products of the workpiece include chips obtained by singulating a wafer. Specifically, semiconductor chips obtained by singulating a semiconductor wafer can be used. In this case, the protective film is formed on the back side of the wafer and chip.

[0048] The “front surface” of a workpiece such as a wafer refers to the surface on which circuits and protruding electrodes such as bumps are formed, while the “back surface” refers to the surface on which no circuits or electrodes (such as protruding electrodes such as bumps) are formed.

[0049] In this specification, for example, “(meth)acrylate” is used as a term representing both “acrylate” and “methacrylate”, and the same applies to other similar terms.

[0050] The release film is a film that supports the protective film forming film in a releasable manner. The film is not limited in thickness and is used as a concept including a sheet.

[0051] The mass ratios in the descriptions of the protective film-forming film composition and the release agent layer composition are based on the active ingredients (solid content), and the solvent is not included unless otherwise specified.

[0052] Hereinafter, the present invention will be described in detail based on specific embodiments in the following order.

[0053] (1. Protective film forming film)

[0054] like Figure 1 、 Figure 5 As shown, the protective film-forming sheet 10 of this embodiment is a long sheet having a protective film-forming film 11 and a first release film 12 provided on one surface of the protective film-forming film 11 , and is usually wound into a roll.

[0055] The protective film-forming film 11 is attached to a workpiece and formed into a protective film, thereby forming a protective film for protecting the workpiece or a product processed from the workpiece.

[0056] "Protecting" means bringing the protective film-forming film 11 into a state having sufficient properties to protect a workpiece or a workpiece-processed product. Specifically, when the protective film-forming film of this embodiment is curable, "protecting" means converting an uncured protective film-forming film into a cured product. In other words, the protective film-forming film that has undergone the protective film-forming process is a cured product of the protective film-forming film and is different from the protective film-forming film.

[0057] After a workpiece is superimposed on the curable protective film-forming film, the protective film-forming film is cured, whereby the protective film can be firmly bonded to the workpiece, and a durable protective film can be formed.

[0058] When the protective film forming film 11 does not contain a curable component and is used in an uncured state, the protective film forming film of this embodiment is converted into a protective film when it is attached to a workpiece.

[0059] When high protection performance is not required, the protective film-forming film does not need to be cured, and thus the protective film-forming film may be non-curable.

[0060] In this embodiment, the protective film-forming film is preferably curable. Therefore, the protective film is preferably a cured product. Examples of cured products include heat-cured products and energy-ray cured products. In this embodiment, the protective film is more preferably a heat-cured product.

[0061] The protective film-forming film preferably has adhesiveness at room temperature (23°C) or preferably develops adhesiveness by heating. This allows the workpiece and the protective film-forming film to be adhered to each other when they are superimposed. This allows for reliable positioning before curing the protective film-forming film.

[0062] The protective film-forming film may be composed of a single layer (single layer) or a plurality of layers. When the protective film-forming film has multiple layers, these multiple layers may be the same as or different from each other, and the combination of layers constituting these multiple layers is not particularly limited.

[0063] In this embodiment, the protective film-forming film is preferably a single layer (monolayer). If the protective film-forming film is composed of multiple layers, there is a risk of delamination due to differences in thermal expansion and contraction between the layers during processes where temperature changes occur (during reflow processing or when using the device). If the protective film-forming film is a single layer, this risk can be reduced.

[0064] The thickness of the protective film-forming film is not particularly limited, but is preferably 100 μm or less, more preferably 70 μm or less, further preferably 45 μm or less, and particularly preferably 30 μm or less. If the thickness of the protective film-forming film is within the above range, even if the punched protective film-forming film comes into contact with or adheres to useless parts when passing through the roller after the punching process, it is easy to separate again after passing through the roller. In addition, the thickness of the protective film-forming film is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. If the thickness of the protective film-forming film is within the above range, the protective performance of the resulting protective film becomes good.

[0065] The thickness of the protective film-forming film refers to the thickness of the entire protective film-forming film. For example, the thickness of a protective film-forming film composed of multiple layers refers to the total thickness of all layers constituting the protective film-forming film.

[0066] The following describes a protective film formed on a chip as a workpiece. Figure 8 The chip 30 with a protective film shown will be described as a protective film formed by converting the protective film forming film of this embodiment into a protective film.

[0067] like Figure 8 As shown, the chip 30 with the protective film is on the back side of the chip 31 (on the Figure 8 A protective film 32 is formed on the surface side of the chip 31 (in the Figure 8 A convex electrode 33 is formed on the lower side (in the middle).

[0068] Chip 31 has a circuit formed on its surface, and protruding electrodes 33 are formed on this surface to electrically connect to the circuit. Chip 30 with a protective film is positioned so that the surface with protruding electrodes 33 faces the chip mounting substrate. Then, through a predetermined heat treatment (reflow soldering), the protruding electrodes 33 are electrically and mechanically connected to the substrate, allowing for mounting. Examples of protruding electrodes 33 include bumps and pillar electrodes.

[0069] (1.1 Adhesion between protective film forming films)

[0070] In this embodiment, the adhesion of the protective film-forming films constituting the protective film-forming sheet when they are attached to each other is controlled within a specified range, thereby suppressing the defective removal of waste. Specifically, the present embodiment is characterized in that the adhesion of the two protective film-forming films after being attached for 2 minutes at 23°C with a load of 2kgf is 19N / 25mm or less. The adhesion is preferably 15N / 25mm or less, and more preferably 11N / 25mm or less. In addition, if the adhesion is too small, the holding performance of the workpiece sometimes decreases, so the adhesion is preferably 0.1N / 25mm or more, more preferably 1N / 25mm or more, and particularly preferably 3N / 25mm or more. In addition, the reason for setting the measurement of the adhesion as 2 minutes after the protective film-forming films are attached to each other is that in the device for removing waste and attaching the workpiece, in the process of the protective film-forming sheet passing through the roller 19, the time for the cut portion to contact the roller 19 and stop is about 2 minutes.

[0071] As described above, by controlling the adhesion between the protective film forming films within a specified range, even if the protective film forming sheet is bent after the punching process, the punched protective film forming film 16 and the useless portion 17 will adhere to each other, and the protective film forming film 16 and the useless portion 17 can be separated again after the protective film forming sheet passes through the roller, thereby reducing the defective waste removal.

[0072] (1.2 Protective Film-Forming Composition)

[0073] As long as the protective film forming film has the above-mentioned physical properties, the composition of the protective film forming film is not particularly limited. In the present embodiment, the composition constituting the protective film forming film (protective film forming film composition) is preferably a resin composition containing at least a polymer component (A), a curable component (B), and a filler (E). The polymer component is regarded as a component formed by a polymerization reaction of a polymerizable compound. In addition, the curable component is a component that can undergo a curing (polymerization) reaction. In addition, the polymerization reaction in the present invention also includes a polycondensation reaction.

[0074] In addition, components contained in the polymer component may also be curable components. In this embodiment, when the protective film-forming film composition contains such components that are both polymer components and curable components, it is considered that the protective film-forming film composition contains the polymer component and the curable component.

[0075] (1.2.1 Polymer composition)

[0076] The polymer component (A) makes the protective film-forming film have film-forming properties and gives it appropriate viscosity so that the protective film-forming film is surely and evenly attached to the workpiece. The weight average molecular weight of the polymer component is usually in the range of 50,000 to 2 million, preferably in the range of 100,000 to 1.5 million, and particularly preferably in the range of 200,000 to 1 million. If the weight average molecular weight is too low, there is a tendency for the adhesion of the protective film-forming films to each other to increase. On the other hand, if the weight average molecular weight is too high, the compatibility with other components deteriorates, which results in the formation of a uniform film. As such polymer components, for example, acrylic resins, urethane resins, phenoxy resins, silicone resins, saturated polyester resins, etc. can be used, and acrylic resins are particularly preferably used.

[0077] In addition, in this specification, unless otherwise specified, the "weight average molecular weight" is a polystyrene conversion value measured by gel permeation chromatography (GPC). As a measurement by this method, for example, a high-efficiency GPC device "HLC-8120GPC" manufactured by TOSOH CORPORATION, in which a high-efficiency chromatography column "TSK gurdcolumn H XL -H","TSK Gel GMH XL ”,TSK Gel G2000 H XL The measurement was performed using a differential refractometer as a detector at a column temperature of 40°C and a liquid feed rate of 1.0 mL / min using a TOSOH CORPORATION device.

[0078] Examples of acrylic resins include (meth)acrylate copolymers composed of a (meth)acrylate monomer and a structural unit derived from a (meth)acrylic acid derivative. Preferred (meth)acrylate monomers include alkyl (meth)acrylates having an alkyl group with 1 to 18 carbon atoms, specifically methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate. Examples of (meth)acrylic acid derivatives include (meth)acrylic acid, glycidyl (meth)acrylate, and hydroxyethyl (meth)acrylate.

[0079] In this embodiment, glycidyl methacrylate or the like is preferably used to introduce glycidyl groups into the acrylic resin. Acrylic resins with glycidyl groups introduced improve compatibility with the epoxy resin (described later as a thermosetting component), resulting in a higher glass transition temperature (Tg) of the protective film-forming film after curing, thereby enhancing heat resistance. Furthermore, in this embodiment, hydroxyethyl acrylate or the like is preferably used to introduce hydroxyl groups into the acrylic resin in order to control adhesion or tackiness to workpieces.

[0080] The glass transition temperature of the acrylic resin is preferably -70°C to 40°C, more preferably -35°C to 35°C, more preferably -20°C to 30°C, even more preferably -10°C to 25°C, and particularly preferably -5°C to 20°C. By setting the glass transition temperature of the acrylic resin within this range, the fluidity of the protective film-forming film and the protective film during heating can be suppressed, thereby facilitating the formation of a smooth protective film. If the glass transition temperature is too low, the adhesion between the protective film-forming films tends to increase. If the glass transition temperature is too high, compatibility with other components deteriorates, resulting in the formation of a uniform film.

[0081] When an acrylic resin has m types of structural units (m is an integer greater than or equal to 2), the glass transition temperature of the acrylic resin can be calculated as follows. Specifically, the m types of monomers from which the structural units in the acrylic resin are derived are sequentially assigned non-repeating numbers from 1 to m and designated "monomer m." The glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox equation shown below.

[0082] [Mathematical formula 1]

[0083]

[0084] Wherein, Tg is the glass transition temperature of the acrylic resin, m is an integer greater than or equal to 2, Tgk is the glass transition temperature of the homopolymer of monomer m, Wk is the mass fraction of the structural unit m derived from monomer m in the acrylic resin, and Wk satisfies the following formula.

[0085] [Mathematical formula 2]

[0086]

[0087] Wherein, m and Wk are the same as those described above.

[0088] As Tgk, the values ​​described in the Polymer Data Handbook, the Adhesion Handbook, or the Polymer Handbook can be used. For example, the Tgk of a homopolymer of methyl acrylate is 10°C, the Tgk of a homopolymer of n-butyl acrylate is -54°C, the Tgk of a homopolymer of methyl methacrylate is 105°C, the Tgk of a homopolymer of 2-hydroxyethyl acrylate is -15°C, the Tgk of a homopolymer of glycidyl methacrylate is 41°C, and the Tgk of 2-ethylhexyl acrylate is -70°C.

[0089] The content of the polymer component is preferably 5 to 80 parts by mass, more preferably 8 to 70 parts by mass, more preferably 10 to 60 parts by mass, even more preferably 12 to 55 parts by mass, even more preferably 14 to 50 parts by mass, and particularly preferably 15 to 45 parts by mass, based on the total weight of the protective film-forming composition of 100 parts by mass. By keeping the content of the polymer component within the above range, the amount of low molecular weight components that increase the adhesion between the protective film-forming films can be limited to a suitable range, thereby facilitating the material design of the protective film-forming composition.

[0090] (1.2.2 Thermosetting components)

[0091] The curable component (B) cures the protective film-forming film to form a hard protective film. A thermosetting component, an energy-ray curable component, or a mixture thereof can be used as the curable component. When cured by energy ray irradiation, the protective film-forming film of this embodiment contains fillers and colorants, etc., which will be described later, and thus has a reduced light transmittance. Therefore, for example, when the protective film-forming film becomes thicker, energy-ray curing tends to be insufficient.

[0092] On the other hand, even when the thickness of the thermosetting protective film forming film increases, it can be fully cured by heating, thereby forming a protective film with high protective performance. In addition, by using conventional heating equipment such as a heating oven, multiple protective film forming films can be heated and thermally cured at once.

[0093] Therefore, in this embodiment, the curable component is preferably thermosetting. In other words, the protective film-forming film of this embodiment is preferably thermosetting.

[0094] Whether a protective film-forming film is thermosetting can be determined as follows. First, a protective film-forming film at room temperature (23°C) is heated to a temperature higher than room temperature and then cooled to room temperature to form a heated and cooled protective film-forming film. Next, at the same temperature, the hardness of the heated and cooled protective film-forming film is compared with the hardness of the protective film-forming film before heating. If the heated and cooled protective film-forming film is harder, the protective film-forming film is determined to be thermosetting.

[0095] Preferred thermosetting components include, for example, epoxy resins, thermosetting polyimide resins, unsaturated polyester resins, and mixtures thereof. Furthermore, thermosetting polyimide resins are a general term for low-molecular-weight, low-viscosity monomers or precursor polymers that are thermally cured to form polyimide resins. Non-limiting examples of thermosetting polyimide resins are described in, for example, the Journal of the Japanese Society of Fiber Research, "Fibers and Industry," Vol. 50, No. 3 (1994), pp. 106-118.

[0096] The epoxy resin, which is a thermosetting component, has the property of forming a three-dimensional network when heated, forming a strong coating. As such epoxy resin, various known epoxy resins can be used. In this embodiment, the molecular weight (formula weight) of the epoxy resin is preferably 300 or more and less than 50,000, 300 or more and less than 10,000, 300 or more and less than 5,000, or 300 or more and less than 3,000. In addition, the epoxy equivalent of the epoxy resin is preferably 50 to 5,000 g / eq, more preferably 100 to 2,000 g / eq, and even more preferably 150 to 1,000 g / eq.

[0097] Specific examples of such epoxy resins include glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenol novolac, and cresol novolac; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidyl or alkylglycidyl epoxy resins in which the active hydrogen bonded to the nitrogen atom of aniline isocyanurate, etc., is substituted with a glycidyl group; and so-called alicyclic epoxides in which epoxy groups are introduced by, for example, oxidizing the carbon-carbon double bond in the molecule, such as vinylcyclohexane diepoxide, 3,4-epoxycyclohexylmethyl-3,4-dicyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane. In addition, epoxy resins having a biphenyl skeleton, a dicyclohexadiene skeleton, a naphthalene skeleton, or the like can also be used.

[0098] When a thermosetting component is used as the curing component (B), it is preferred to use a curing agent (C) as an auxiliary agent. As a curing agent for epoxy resin, a heat-activated latent epoxy resin curing agent is preferred. "Heat-activated latent epoxy resin curing agent" is a type of curing agent that is difficult to react with epoxy resin at room temperature (23°C), but is activated by heating to a certain temperature or above, thereby reacting with epoxy resin. Methods for activating heat-activated latent epoxy resin curing agents include a method of generating active species (anions, cations) in a chemical reaction based on heating; a method of stably dispersing in epoxy resin at around room temperature, but being compatible with epoxy resin, dissolving and initiating a curing reaction at high temperature; a method of dissolving a molecular sieve-encapsulated curing agent at high temperature and initiating a curing reaction; a method based on microcapsules, etc.

[0099] Among the methods exemplified above, a method in which the precipitant is stably dispersed in the epoxy resin at around room temperature but is compatible with and dissolved in the epoxy resin at high temperature to initiate a curing reaction is preferred.

[0100] Specific examples of heat-activated latent epoxy resin curing agents include various onium salts, dibasic acid dihydrazide compounds, dicyandiamide, amine adduct curing agents, imidazole compounds, and other high-melting-point active hydrogen compounds. These heat-activated latent epoxy resin curing agents can be used alone or in combination of two or more. In this embodiment, dicyandiamide is particularly preferred.

[0101] In addition, as a curing agent for epoxy resin, phenolic resin is also preferred. As the phenolic resin, condensates of phenols such as alkylphenols, polyphenols, naphthols and aldehydes can be used without particular limitation. Specifically, phenol novolac resin, o-cresol novolac resin, p-cresol novolac resin, tert-butylphenol novolac resin, dicyclopentadiene cresol resin, poly-p-vinyl phenolic resin, bisphenol A novolac resin or modified products thereof can be used.

[0102] The phenolic hydroxyl groups contained in these phenol resins can easily undergo an addition reaction with the epoxy groups of the above-mentioned epoxy resins by heating, thereby forming a cured product having high impact resistance.

[0103] The content of the curing agent (C) is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.2 to 15 parts by mass, and particularly preferably 0.3 to 10 parts by mass, relative to 100 parts by mass of the epoxy resin. By setting the content of the curing agent (C) within the above range, the network structure of the protective film becomes dense, and the performance of the protective film in protecting the workpiece is easily achieved.

[0104] When dicyandiamide is used as the curing agent (C), it is preferred to use a curing accelerator (D) simultaneously. Preferred curing accelerators include imidazoles (imidazoles in which one or more hydrogen atoms are replaced by 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. Among these, 2-phenyl-4-methyl-5-hydroxymethylimidazole is particularly preferred.

[0105] The content of the curing accelerator is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, even more preferably 0.2 to 15 parts by mass, and particularly preferably 0.3 to 10 parts by mass, relative to 100 parts by mass of the epoxy resin. By setting the content of the curing accelerator (D) within the above range, the network structure of the protective film becomes dense, thereby easily achieving the performance of the protective film in protecting the workpiece.

[0106] The combined content of the thermosetting component and curing agent is preferably 3 to 80 parts by mass, more preferably 5 to 60 parts by mass, more preferably 7 to 50 parts by mass, even more preferably 9 to 40 parts by mass, and particularly preferably 10 to 30 parts by mass, based on 100 parts by mass of the total weight of the protective film-forming composition. When the thermosetting component and curing agent are blended in this ratio, moderate adhesion is achieved before curing, allowing for stable application. Furthermore, after curing, the protective film is more likely to provide the desired performance, protecting the workpiece.

[0107] If low molecular weight compounds are used as thermosetting components and curing agents, the viscosity of the protective film-forming film may increase, and the adhesion between the protective film-forming films may increase. Therefore, it is preferable to select the type and amount of thermosetting components and curing agents within the above range so as to control the viscosity to an appropriate value.

[0108] (1.2.3 Energy ray curable component)

[0109] When the curable component (B) is an energy ray-curable component, the energy ray-curable component is preferably uncured, preferably has adhesiveness, and more preferably is uncured and has adhesiveness.

[0110] The energy ray-curable component is a component that is cured by irradiation with energy rays and is a component for imparting film-forming properties, flexibility, and the like to the protective film-forming film.

[0111] As the energy-ray curable component, for example, a compound having an energy-ray curable group is preferable. Examples of such a compound include known energy-ray curable components.

[0112] If a low molecular weight compound is used as an energy-ray curable component, the viscosity of the protective film-forming film may increase, and the adhesion between the protective film-forming films may increase. Therefore, it is preferable to select the type and amount of the energy-ray curable component so as to control the viscosity to an appropriate value.

[0113] (1.2.4 Filling materials)

[0114] By incorporating a filler (E) into the protective film-forming film, the thermal expansion coefficient of the protective film formed by converting the protective film into a protective film can be easily adjusted. By adjusting the thermal expansion coefficient to be close to that of the workpiece, the bonding reliability of the package formed using the protective film-forming film is further improved. Furthermore, by incorporating a filler (E) into the protective film-forming film, a hard protective film can be obtained, further reducing the moisture absorption rate of the protective film, and further improving the bonding reliability of the package.

[0115] The filler (E) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler from the viewpoint of shape stability at high temperatures.

[0116] Preferred inorganic fillers include powders such as silica, alumina, talc, calcium carbonate, red iron oxide, silicon carbide, and boron nitride; beads obtained by sphericalizing these inorganic fillers; surface-modified products of these inorganic fillers; single-crystal fibers of these inorganic fillers; and glass fibers. Among these, silica and surface-modified silica are preferred. Surface-modified silica is preferably surface-modified using a coupling agent, more preferably using a silane coupling agent.

[0117] The average particle size of the filler is preferably 0.02 to 10 μm, more preferably 0.05 to 5 μm, and particularly preferably 0.10 to 3 μm.

[0118] By setting the average particle size of the filler to the above value, the workability of the protective film-forming composition becomes good, and thus the quality of the protective film-forming composition and the protective film-forming film tends to be stabilized.

[0119] In addition, unless otherwise specified, the "average particle size" in this specification refers to the particle size (D50) at 50% of the cumulative value in the particle size distribution curve determined by a laser diffraction scattering method.

[0120] The filler content is preferably 15 to 80 parts by mass, more preferably 30 to 75 parts by mass, even more preferably 40 to 70 parts by mass, and particularly preferably 45 to 65 parts by mass, based on 100 parts by mass of the total weight of the protective film-forming film composition.

[0121] By setting the filler content to the above values, it is easier to control the adhesion between the protective film-forming films within an appropriate range. If the filler content is too low, the viscosity of the protective film-forming films increases, and the adhesion between the protective film-forming films increases excessively. On the other hand, if the filler content is too high, the conformability of the protective film-forming films may decrease, and the films may lose their shape due to bending on the roller, resulting in an excessive decrease in the viscosity of the protective film-forming films and their adhesion to the workpiece.

[0122] Furthermore, the protective film-forming film preferably contains two or more fillers. That is, the filler (E) is preferably a mixture of two or more fillers. “Containing two or more fillers” may include two or more fillers of different materials or two or more fillers of different average particle sizes.

[0123] In this embodiment, it is preferred to include two or more fillers with different average particle sizes. By including fillers with different average particle sizes in the protective film-forming film, it is easier to place a filler with a smaller average particle size in the gaps between fillers with a larger average particle size. This results in the aforementioned effects and facilitates setting the adhesion between the protective film-forming films within the aforementioned range.

[0124] When two or more fillers having different average particle sizes are contained, the average particle size of the filler with the largest average particle size is preferably 1.5 to 100 times, more preferably 2 to 20 times, and even more preferably 3 to 18 times the average particle size of the filler with the smallest average particle size.

[0125] Furthermore, whether or not the protective film or protective film-forming film contains two or more fillers having different average particle sizes can be confirmed by observing a cross section of the protective film or protective film-forming film.

[0126] (1.2.5 Coupling agent)

[0127] The protective film-forming film preferably contains a coupling agent (F). The inclusion of a coupling agent can improve the adhesion between the protective film and the workpiece while maintaining the heat resistance of the protective film after curing, and can also improve water resistance (resistance to moist heat). Silane coupling agents are preferred as coupling agents due to their versatility and cost advantages.

[0128] Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(methacryloxypropyl)trimethoxysilane, γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-6-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis(3-triethoxysilylpropyl)tetrasulfide, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, and imidazolesilane. These silane coupling agents may be used alone or in combination of two or more.

[0129] When the total weight of the protective film-forming film composition is 100 parts by mass, the content of the coupling agent is preferably 0.01 to 20 parts by mass, 0.1 to 10 parts by mass, 0.2 to 5 parts by mass, or 0.3 to 3 parts by mass.

[0130] (1.2.6 Colorants)

[0131] The protective film-forming film preferably contains a colorant (G). This shields the backside of the workpiece, such as a chip, from various electromagnetic waves generated within electronic devices, thus reducing malfunctions of the workpiece, such as the chip. Furthermore, any defective waste removal can be immediately detected with the naked eye.

[0132] As the colorant (G), for example, known colorants such as inorganic pigments, organic pigments, and organic dyes can be used. In the present embodiment, inorganic pigments are preferred.

[0133] As inorganic pigments, for example, carbon black, cobalt pigments, iron pigments, chromium pigments, titanium pigments, vanadium pigments, zirconium pigments, molybdenum pigments, ruthenium pigments, platinum pigments, ITO (indium tin oxide) pigments, ATO (antimony tin oxide) pigments etc. can be listed. Among them, carbon black is particularly preferably used. Carbon black can block electromagnetic waves of a wider wavelength range.

[0134] The amount of colorant (especially carbon black) added to the protective film-forming film varies depending on the thickness of the protective film-forming film. For example, when the thickness of the protective film-forming film is 20 μm, the content of the colorant is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass, based on the total weight of the protective film-forming film composition being 100 parts by mass.

[0135] The average particle size of the colorant (especially carbon black) is preferably 1 to 500 nm, particularly preferably 3 to 100 nm, and further preferably 5 to 50 nm. When the average particle size of the colorant is within the above range, it is easy to control the light transmittance within the desired range.

[0136] (1.2.7 Other additives)

[0137] The protective film-forming film composition may contain other additives such as a photopolymerization initiator, a crosslinking agent, a plasticizer, an antistatic agent, an antioxidant, a getter, a tackifier, and a release agent, within a range not impairing the effects of the present invention.

[0138] The content of the stripping agent in the protective film-forming film composition is preferably less than a specified amount. In this embodiment, it is preferably less than 0.00099% by mass relative to the total mass of the protective film-forming film. If the content of the stripping agent is too high, the reliability of the adhesion between the protective film and the workpiece tends to decrease. Examples of the stripping agent include alkyd stripping agents, silicone stripping agents, fluorine stripping agents, unsaturated polyester stripping agents, polyolefin stripping agents, and wax stripping agents.

[0139] (1.2.8 Control of Adhesion Between Protective Film Forming Films)

[0140] As described above, the present embodiment is characterized in that the adhesive force when the protective film-forming films constituting the protective film-forming sheet are attached to each other is controlled within a predetermined range, thereby suppressing waste removal defects.

[0141] The adhesion between the protective film-forming films can be controlled by the types and blending amounts of the components constituting the protective film-forming films.

[0142] If the weight average molecular weight of the polymer component (A) is low, there is a tendency for the adhesion to increase. If the glass transition temperature of the polymer component (A) is low, there is a tendency for the adhesion to increase. In addition, if a low molecular weight compound is used as the curable component (B), curing agent (C), curing accelerator (D), or energy ray curable component, there is a tendency for the adhesion to increase. If the blending amount of the filler (E) is large, there is a tendency for the adhesion to decrease.

[0143] By partially curing the protective film forming film, the adhesion can also be controlled. For example, by partially curing the curable component (B), the adhesion can be reduced. The timing of partially curing the protective film forming film is not particularly limited, for example, as long as it is before the roller 19 is passed when punching the protective film forming sheet. However, from the perspective of setting the peeling forces F1 and F2 described later within an appropriate range and the adhesion to the workpiece, the protective film forming film is preferably not partially cured as described in the embodiments described later.

[0144] (2. Sheet for forming protective film)

[0145] Before using the protective film forming film, you can Figure 1 As shown, the protective film forming sheet 10 having a double-layer structure in which a peelable protective film forming film 11 is laminated on a first peeling film 12 is rolled up and stored. Figure 3 As shown, a protective film forming sheet 20 having a three-layer structure (another embodiment) is wound and stored with the protective film forming film 11 sandwiched between two release films (a first release film 12 and a second release film 13). The release films are peeled off when the protective film forming film is used.

[0146] The protective film forming sheet is long and is wound into a roll for storage and transportation. As such a protective film forming sheet, a protective film forming sheet is also known in which a protective film forming film is punched into a shape roughly the same as the workpiece. The protective film forming film 16 punched into a predetermined closed shape in such a punched protective film forming sheet is laminated on the first release film 12 ( Figure 2 ), or sandwiched between two release films (12, 13) ( Figure 4 ).

[0147] The first release film can be composed of a single layer (monolayer) or two or more layers of a substrate. From the perspective of controlling the release properties, the surface of the substrate may be subjected to a release treatment. That is, the surface of the substrate may be modified, or a material other than the substrate may be formed on the surface of the substrate. In this embodiment, the first release film preferably comprises a substrate and a release agent layer. The presence of a release agent layer facilitates control of the physical properties of the surface of the first release film on which the release agent layer is formed. In this embodiment, a coating containing a release agent layer composition (described later) is applied to one surface of the substrate, and the coating is dried and cured to form the release agent layer. This produces the first release film.

[0148] The thickness of the first release film 12 is not particularly limited, but is preferably 30 to 100 μm, more preferably 40 to 80 μm, and even more preferably 45 to 70 μm.

[0149] By setting the lower limit of the thickness of the first release film 12 to the above value, it is possible to prevent the cutter from penetrating the first release film 12 and cutting the first release film 12 when the protective film-forming film is cut with a cutter. In addition, after the protective film-forming sheet 10 is unwound and the protective film-forming film 11 is cut out, the protective film-forming sheet 10 passes through rollers such as guide rollers within the apparatus before being transported to the next step. However, by setting the upper limit of the thickness of the first release film 12 to the above value, it is possible to prevent the protective film-forming film 11 from peeling off from the first release film 12.

[0150] The thickness of the first release film 12 refers to the thickness of the entire first release film. For example, the thickness of a first release film composed of a plurality of layers refers to the total thickness of all layers constituting the first release film.

[0151] As the base material of the first peeling film 12, resin film and paper can be listed. As the resin of the resin film, polyethylene terephthalate, polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polybutylene terephthalate, polyurethane, ethylene-vinyl acetate copolymer, ionomer resin, ethylene (meth) acrylic acid copolymer, polystyrene, polycarbonate, fluororesin, low-density polyethylene, linear low-density polyethylene and triacetyl cellulose can be listed. As paper, high-quality paper, coated paper (coat paper), glassine and laminated paper can be listed. These base materials can be used alone or in combination. Among them, polyethylene terephthalate film is preferred from the perspective of being cheap and having rigidity.

[0152] At least one surface of the first release film 12 (the surface laminated with the protective film-forming film) may be subjected to a release treatment using a release agent layer composition. The thickness of the release agent layer is preferably 30 nm to 200 nm, more preferably 50 nm to 180 nm.

[0153] The surface elastic modulus (23°C) of the first release film 12 on the surface in contact with the protective film-forming film 11 is preferably 17 MPa or less, more preferably 14 MPa or less, even more preferably 13 MPa or less, and particularly preferably 12 MPa or less. The surface elastic modulus is an indicator of the ease with which a surface deforms. By setting the surface elastic modulus of the first release film 12 on the surface in contact with the protective film-forming film 11 within the above range, it is possible to suppress the occurrence of lifting (peeling of approximately 1 to 4 mm) between the protective film-forming film 11 and the first release film 12 when the die is pressed and then pulled up during the punching process. This is believed to be because the surface of the first release film 12 is relatively soft, and even under compression due to the die and release due to its release, the surface of the first release film follows the deformation of the protective film-forming film. By suppressing the occurrence of lifting, defects in waste removal can be further reduced. The lower limit of the surface elastic modulus of the surface of the first release film 12 in contact with the protective film-forming film 11 is not particularly limited, but if the surface elastic modulus is too low, the peeling force may increase, so it is preferably 3 MPa.

[0154] It is more preferably 4 MPa or more, more preferably 5 MPa or more.

[0155] The surface elastic modulus of the surface of the first release film 12 in contact with the protective film-forming film 11 at 23°C can be measured using an atomic force microscope equipped with a cantilever. Specifically, the surface of the first release film 12 in contact with the protective film-forming film 11 is pressed and pulled away by the cantilever to generate a force curve. The resulting force curve is fitted using the JKR theory to determine the elastic modulus, which is the surface elastic modulus of the present invention. The specific measurement method will be described in detail in the Examples below.

[0156] In order to set the peeling force F1 described later within an appropriate range and set the surface elastic modulus of the first peeling film 12 within the above range, in this embodiment, as a composition for the peeling agent layer, for example, alkyd release agents, silicone release agents, fluorine release agents, unsaturated polyester release agents, polyolefin release agents, and wax release agents are preferred. Among them, silicone release agents are preferred, and particularly preferred are those containing silicone release agents and heavy-peeling additives.

[0157] As the silicone-based release agent, a silicone release agent containing silicone having dimethylpolysiloxane as a basic skeleton can be used.

[0158] The silicone can be any of addition-reaction type, condensation-reaction type, and energy-ray curing types such as UV-curable and electron-beam curable, but addition-reaction type silicone is preferred. Addition-reaction type silicones offer high reactivity and excellent productivity, and compared to condensation-reaction type silicones, they have advantages such as minimal variation in release strength after production and no curing shrinkage.

[0159] Specific examples of addition-reaction silicones include organopolysiloxanes having two or more alkenyl groups with 2 to 10 carbon atoms, such as vinyl, allyl, propenyl, and hexenyl, at the molecular ends and / or in the side chains. From the perspective of reducing the surface elastic modulus, it is preferable that the number of alkenyl groups in addition-reaction silicones is small.

[0160] When the total weight of the release agent layer composition (excluding the catalyst described below) is 100 parts by mass, the content of the organosilicon composed of dimethylpolysiloxane is preferably less than 100 parts by mass, more preferably less than 90 parts by mass, more preferably less than 80 parts by mass, and particularly preferably less than 70 parts by mass.

[0161] When using such an addition reaction type silicone, it is preferred to use a crosslinking agent and a catalyst simultaneously.

[0162] Examples of the crosslinking agent include organopolysiloxanes having at least two silicon atoms bonded to hydrogen atoms in one molecule. From the perspective of reducing the surface elastic modulus, the crosslinking agent content in the release agent layer composition is preferably low.

[0163] Specific examples of the crosslinking agent include dimethylhydrogensiloxane-methylhydrogensiloxane copolymers terminated with dimethylhydrogensiloxane, trimethylhydrogensiloxane-methylhydrogensiloxane copolymers terminated with trimethylhydrogensiloxane, and poly(hydrogensilsesquioxane).

[0164] Examples of the catalyst include fine-particle platinum, fine-particle platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, and platinum group metal compounds such as palladium and rhodium.

[0165] By using such a catalyst, the curing reaction of the release agent layer composition can be carried out more efficiently.

[0166] From the perspective of setting the surface elastic modulus within the above range and setting the peeling force F1 described later within an appropriate range, when the total weight of the release agent layer composition (excluding the catalyst) is set to 100 parts by mass, the content of the silicone release agent is preferably 30 to 100 parts by mass, and more preferably 50 to 100 parts by mass.

[0167] The heavy release additive is used to increase the release force F1 described below. Examples of the heavy release additive include silicone resins and organosilanes such as silane coupling agents, and silicone resins are preferred.

[0168] As the silicone resin, for example, MQ resin containing a monofunctional siloxane unit [R3SiO 1 / 2 ] and the M unit as a tetrafunctional siloxane unit [SiO 4 / 2] Q unit. Furthermore, the three Rs in the M unit each independently represent a hydrogen atom, a hydroxyl group, or an organic group. From the perspective of easily suppressing silicone migration, at least one of the three Rs in the M unit is preferably a hydroxyl group or a vinyl group, more preferably a vinyl group. From the perspective of reducing the surface elastic modulus, the content of the silicone resin (particularly the MQ resin) in the release agent layer composition is preferably low.

[0169] The content of the heavy-duty release additive is preferably 0 to 50 parts by mass, more preferably 5 to 45 parts by mass, and particularly preferably 10 to 40 parts by mass, based on 100 parts by mass of the total weight of the release agent layer composition (excluding the catalyst).

[0170] From the perspective of adjusting viscosity and improving coating properties on substrates, the release agent layer composition is preferably used as a coating agent containing a diluent solvent in addition to the various active ingredients described above. In this specification, "active ingredient" refers to the components contained in the coating agent containing the target composition, excluding the diluent solvent.

[0171] Examples of the dilution solvent include organic solvents such as aromatic hydrocarbons such as toluene, fatty acid esters such as ethyl acetate, ketones such as methyl ethyl ketone, and aliphatic hydrocarbons such as hexane and heptane. These dilution solvents may be used alone or in combination of two or more.

[0172] The active ingredient (solid content) concentration of the coating agent containing the release agent layer composition is preferably 0.3 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 0.5 to 3% by mass.

[0173] The release agent layer composition may contain additives commonly used in release agent layers, as long as the effects of the present invention are not impaired. Examples of such additives include dyes and dispersants.

[0174] In the protective film-forming sheet 10 of this embodiment, the protective film-forming film 11 is preferably punched into a predetermined shape. Specifically, the protective film-forming sheet is preferably provided with a cutout 14 so that a portion of the protective film-forming sheet 10 has a predetermined closed shape when viewed from above. Furthermore, to prevent the protective film-forming film from overflowing from the workpiece when attached to the workpiece, the shape of the punched protective film-forming film is preferably smaller than the workpiece.

[0175] (3. Method for Manufacturing Protective Film-Forming Sheet)

[0176] The method for producing the protective film-forming film is not particularly limited. The film can be produced using a coating agent containing the protective film-forming film composition. The coating agent can be prepared by mixing the components constituting the protective film-forming film composition using a known method.

[0177] The obtained coating agent is applied to the release surface of the first release film 12 using a coating machine such as a roll coater, a knife coater, a roll knife coater, an air knife coater, a die coater, a rod coater, a gravure coater, or a curtain coater, and then dried. This produces the protective film-forming sheet 10 of this embodiment, which has the protective film-forming film 11 on the first release film 12. Alternatively, the coating agent may be applied to another resin film, dried, and the resulting protective film-forming film transferred to the first release film. To produce the protective film-forming sheet 20 of another embodiment, a second release film 13 is applied to the exposed surface of the protective film-forming film 11 laminated with the first release film 12, producing the protective film-forming sheet 20 in which the protective film-forming film 11 is sandwiched between two release films.

[0178] (4. Method for Manufacturing Punched Protective Film-Forming Sheet)

[0179] A method for punching the protective film-forming sheet 10 to obtain the protective film-forming film 16 punched into a predetermined closed shape on the first release film 12 will be described.

[0180] (4.1 Punching process)

[0181] First, prepare Figure 1 The protective film forming sheet 10 shown is not punched. Using a punch die (not shown), a cut 14 is cut from the protective film forming film 11 side of the protective film forming sheet 10 so as to penetrate the protective film forming film 11 and reach a portion of the surface of the first peeling film 12. The operation of cutting a cut so as to reach a portion of the surface without completely cutting is called a half-cut. As a result, a cut 14 having a predetermined closed shape is formed on a portion of the surface of the protective film forming sheet 10 (see Figure 2 、 Figure 5 Here, when the protective film-forming film is transferred onto a semiconductor wafer, the predetermined closed shape is substantially the same as the shape of the wafer. Specifically, the cutout 14 is formed to have a shape substantially the same as the shape of the workpiece to which the protective film-forming film 11 is attached or the shape of the area where the protective film is to be formed. This process is referred to as a "punching process."

[0182] The punching step divides the protective film-forming film 11 into a protective film-forming film 16 punched into a predetermined closed shape and a surrounding, continuous, useless portion 17. The protective film-forming film 16 punched into a predetermined closed shape is provided at multiple locations along the longitudinal direction of the protective film-forming sheet 10.

[0183] In the punching process, a known die can be used as appropriate. The punching is performed by half-cutting so as to completely cut the protective film-forming film 11 and not completely cut the first release film 12.

[0184] like Figure 2 、 Figure 4 As shown, the cross-sectional shape of the cut 14 is generally wedge-shaped, with the width of the cut 14 being wider on the upper surface side of the protective film-forming film 11 where the punch enters and narrowing on the lower surface side (the interface between the protective film-forming film 11 and the first release film 12). The width of the cut 14 is not particularly limited, but from the perspective of preventing contact and adhesion between the punched protective film-forming film 16 and the useless portion 17, or from the perspective of shortening the contact and adhesion time, the width D of the cut 14 on the lower surface of the protective film-forming film 11 (i.e., the upper surface of the first release film 12) is preferably 8 μm or greater, more preferably 10 μm or greater, further preferably 15 μm or greater, and particularly preferably 20 μm or greater. The width D can be measured by cutting the protective film-forming sheet in the thickness direction and measuring the width of the cut on the upper surface of the first release film 12 in the cross section. The upper limit of the width D is not particularly limited, but considering the width of the dicing blade that can reliably cut the protective film-forming film, it is generally 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less. To form the incision 14, a die having a dicing blade with a wide blade width at the front end is preferably used.

[0185] After the above steps, a punched protective film-forming sheet 10 is obtained. The protective film-forming sheet is provided with a cutout 14 so that a portion of the sheet has a predetermined closed shape (e.g., a shape roughly identical to the planar shape of a semiconductor wafer) when viewed from the upper surface of the protective film-forming film 11. The cutout 14 extends through the thickness of the protective film-forming sheet 10 to a portion of the first release film 12. In other words, the cutout is also formed on the surface of the first release film 12 that contacts the protective film-forming film 11. By allowing the dicing blade to reach the first release film 12, the protective film-forming film 11 can be completely cut.

[0186] (4.2 Waste Removal Process)

[0187] After the punching process and before the waste material removing process, the protective film forming sheet 10 passes through a plurality of rollers such as guide rollers for the purpose of controlling the tension of the protective film forming sheet.

[0188] like Figure 6As shown, in the waste removal step, a continuous unnecessary portion 17 is peeled off from the first release film 12, leaving the punched protective film forming film 16 on the first release film 12. The peeled unnecessary portion 17 is wound on a waste roller.

[0189] According to the protective film-forming sheet 10 of this embodiment, since the adhesion between the protective film-forming films is low, even if the punched protective film-forming film 16 comes into contact with and adheres to the unnecessary portion 17 when passing through the roller 19 or the like after the punching process, the protective film-forming film 16 and the unnecessary portion 17 can be separated again after passing through the roller. As a result, it is possible to suppress defective waste removal in the waste removal process.

[0190] The punched protective film-forming sheet 10 can be wound into a roll for storage and transportation.

[0191] (5. Workpiece processing method)

[0192] As an example of a method for processing a workpiece using the punched protective film forming sheet of this embodiment, a method for manufacturing a package in which a chip with a protective film obtained by processing a wafer with a protective film formed thereon is arranged on a substrate will be described.

[0193] The method for manufacturing the device of this embodiment includes at least the following steps 1 to 9.

[0194] Step 1: Punching the protective film forming sheet 10

[0195] Step 2: Passing the punched protective film-forming sheet between rollers

[0196] Step 3: Step of removing the unnecessary portion 17 of the protective film forming sheet 10

[0197] Step 4: Step of attaching the protective film forming film 11 of the protective film forming sheet 10 to the back surface of the wafer

[0198] Step 5: The process of forming the attached protective film into a protective film

[0199] Step 6: Peeling off the first peeling film from the protective film or protective film forming film Step 7: Singulating the wafer having the protective film or protective film forming film on the back to obtain a plurality of chips with the protective film or protective film forming film

[0200] Step 8: Place the chip with the protective film or protective film forming film on the substrate

[0201] Step 9: Step of heating the chip with the protective film or protective film-forming film disposed on the substrate and the substrate

[0202] Steps 1 to 3 are as described above. Step 5 can be performed before step 6 or after any of steps 6 to 9. That is, the step of converting the protective film forming film into a protective film can be performed at any stage after the protective film forming film is attached to the wafer.

[0203] A method for manufacturing the device including the above-mentioned steps 1 to 9 will be described with reference to the drawings.

[0204] Figure 2 、 Figure 4 、 Figure 5 The outline of step 1 is shown above. Figure 6 The outline of step 3 is shown.

[0205] like Figure 9 As shown, the protective film forming film 11 of the protective film forming sheet 10 is attached to the back surface of the wafer 21 (step 4). Then, the attached protective film forming film 11 is converted into a protective film to form a protective film 32 (step 5), thereby obtaining a wafer with a protective film. When the protective film forming film 11 is thermosetting, the protective film forming film 11 can be heated at a predetermined temperature for an appropriate time. In addition, when the protective film forming film 11 is energy-ray curable, an energy-ray-transmitting film can be used as the first release film 12, and the energy rays can be incident from the first release film 12 side.

[0206] Furthermore, the protective film forming film 11 may be cured after the dicing step described later, or the protective film forming film 11 may be cured after the chip with the protective film forming film is picked up from the dicing sheet.

[0207] Then, the wafer 21 with the protective film is transferred to a known cutting blade 22, and the wafer 21 with the protective film is cut, as shown in FIG. Figure 10 As shown, a chip 31 with a protective film 32 (a chip 30 with a protective film) is obtained (step 7). Then, the dicing sheet 22 is expanded in the planar direction as needed, and the chip 30 with a protective film is picked up from the dicing sheet 22 using a suction nozzle (not shown).

[0208] The picked-up chip 30 with a protective film may be transported to the next process, or may be temporarily stored on a tray, tape, or the like and transported to the next process after a predetermined period of time.

[0209] like Figure 11 As shown, the chip 30 with a protective film, which is being transported to the next step, is transferred to the substrate 50 by the nozzle. The terminal portion on the substrate is released from the nozzle and arranged in a position where the convex electrodes 33 such as bumps can be connected to the terminal portion such as pads (step 8). At this time, other chips other than the chip 30 with a protective film can also be mounted on the substrate 50. Therefore, multiple chips can be mounted on the substrate.

[0210] The chip with the protective film placed at a predetermined position on the substrate is subjected to a heat treatment (reflow treatment) (step 9). The reflow treatment conditions are preferably, for example, a maximum heating temperature of 180 to 350° C. and a reflow time of 2 to 10 minutes.

[0211] During the reflow process, the bump electrodes 33 of the chip with protective film 30 are melted and electrically and mechanically connected to the terminal portion on the substrate, and the chip with protective film 30 is mounted on the substrate.

[0212] (6. Modification)

[0213] In the above, the embodiment of the present invention is described by taking as an example a protective film forming sheet having a double-layer structure having a protective film forming film 11 on a first release film 12, but a second release film 13 may be laminated on the exposed surface of the protective film forming film 11. That is, the protective film forming sheet may be a protective film forming sheet 20 (see FIG. 1 ) in which the protective film forming film 11 is sandwiched between the first release film 12 and the second release film 13. Figure 3 、 Figure 4 At this time, the second release film 13 may be peeled off before the protective film-forming film 11 is attached to the workpiece.

[0214] The material and preferred form of the protective film-forming film 11 of the protective film-forming sheet 20 are the same as those in the above embodiment, and the first release film 12 is also the same as that described in the above embodiment.

[0215] Furthermore, in this embodiment, in the protective-film-forming sheet 20, when the peeling force when peeling the first release film 12 from the protective-film-forming film 11 is represented by F1, and when the peeling force when peeling the second release film 13 from the protective-film-forming film 11 is represented by F2, it is preferable that F1 and F2 satisfy the relationship F1>F2. By satisfying this relationship, when the second release film 13 is removed from the protective-film-forming sheet 20, the protective-film-forming film 16 that should remain is not removed along with the second release film 13, and the protective-film-forming film 16 is more likely to remain on the first release film 12, further suppressing poor waste removal.

[0216] Therefore, the first release film 12 is a heavy release film having a strong release force, and the second release film 13 is a light release film having a weak release force.

[0217] The peel force F1 is preferably 50 mN / 100 mm or greater, more preferably 70 mN / 100 mm or greater, even more preferably 90 mN / 100 mm or greater, even more preferably 110 mN / 100 mm or greater, and particularly preferably 130 mN / 100 mm or greater. By setting F1 within the above range, unintended peeling of the protective film-forming film 11 and the first release film 12 can be suppressed.

[0218] The release force can be adjusted by, for example, controlling the type of release agent layer composition and the thickness of the release agent layer. The second release film 13 is designed to have a lower release force than the first release film 12. If the second release film 13 includes a release agent layer, there are no particular limitations as long as the release agent layer is composed of a material that imparts releasability. For example, the release agent layer of the second release film 13 can be obtained by curing a release agent layer composition containing silicone, the same as that of the first release film 12.

[0219] As long as the above relationship between F1 and F2 is satisfied, the release agent layer composition of the second release film 13 can be selected from the materials exemplified for the first release film 12. However, the materials exemplified as heavy release additives are preferably contained in a smaller amount than in the first release film 12 or not contained at all.

[0220] The thickness of the second release film 13 is not particularly limited, but is preferably 10 μm or more and 75 μm or less. Furthermore, the thickness of the second release film is more preferably 18 μm or more, and even more preferably 24 μm or more. Furthermore, the thickness of the second release film is more preferably 60 μm or less, and even more preferably 45 μm or less. To achieve the above-mentioned relationship of F1 > F2 for the release force F2 and the release force F1, the thickness of the second release film is preferably less than or equal to the thickness of the first release film, and more preferably less than the thickness of the first release film.

[0221] The thickness of the second release film refers to the thickness of the entire second release film. For example, the thickness of a second release film composed of multiple layers refers to the total thickness of all layers constituting the second release film.

[0222] The method for producing the protective film-forming sheet 20 is as described in the embodiment, and the second release film 13 may be bonded to the exposed surface of the protective film-forming film 11 laminated with the first release film 12 .

[0223] Punching the protective film-forming sheet 20 is performed in the same manner as in the above embodiment, except that the punch is inserted from the second release film 13 side and the protective film-forming film 11 and the second release film 13 are cut into a predetermined closed shape. As a result, the punched protective film-forming film 11 and the second release film 13 are formed on the first release film 12. The punched protective film-forming sheet 20 can be wound into a roll for storage and transportation.

[0224] In the waste material removal step, the second release film 13 and the unnecessary portion 17 are simultaneously wound and removed. At this time, the second release film 13, which has been completely cut by the punching process, is reattached using a long adhesive tape, making it easier to remove the second release film 13. As a result, the protective film-forming film 16, which has been cut into a predetermined closed shape, remains on the first release film 12.

[0225] As mentioned above, although embodiment of this invention was demonstrated, this invention is not limited at all to the said embodiment, It can change in various forms within the scope of this invention.

[0226] Example

[0227] Hereinafter, the present invention will be described in further detail using examples, but the present invention is not limited to these examples.

[0228] (Manufacture of Protective Film-Forming Sheet)

[0229] [First release film (heavy release film)]

[0230] <Coating agent containing release agent layer composition>

[0231] The following release agent layer composition raw materials were prepared.

[0232] A silicone-based release agent containing an organopolysiloxane having a vinyl group and an organopolysiloxane having a hydrosilyl group (manufactured by Dow Corning Toray Co., Ltd., BY24-561, solid content 30% by mass)

[0233] Dimethylpolysiloxane (weight average molecular weight: 2000) (manufactured by Shin-Etsu Chemical Co., Ltd., X-62-1387, solid content: 100% by mass)

[0234] MQ resin having a vinyl group as a heavy release additive (manufactured by Dow Corning Toray Co., Ltd., SD-7292, solid content 71% by mass)

[0235] Platinum (Pt) catalyst (manufactured by Dow Corning Toray Co., Ltd., SRX-212, solid content: 100% by mass)

[0236] The above raw materials were added to a mixed solvent of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 1 / 1 (mass ratio)) at the blending ratio (solid content conversion) listed in Table 1 to adjust the total solid content to 2 mass %, thereby preparing a coating agent containing a composition for a release agent layer.

[0237] <Manufacturing of the First Release Film>

[0238] A coating agent containing a release agent layer composition was applied to a PET film (manufactured by Mitsubishi Chemical Corporation, trade name: DIAFOIL (registered trademark) T-100, thickness: 50 μm) so that the film thickness after drying was 0.15 μm. The coating agent was then heated and dried to form a release agent layer on the PET film, thereby producing first release films (heavy release films) A to C.

[0239] <Measurement of Surface Elastic Modulus>

[0240] The surface elastic modulus of the release-treated surface of the obtained first release film was measured in the following manner.

[0241] A cantilever of silicon nitride material (manufactured by Bruker Corporation, trade name: MLCT, tip radius: 20 nm, resonance frequency: 125 kHz, spring constant: 0.6 N / m) was set on an atomic force microscope (manufactured by Bruker Corporation, MultiMode 8). The manufactured first peeling film was placed on the atomic force microscope, and the surface of the peeling agent layer of the manufactured first peeling film was pressed and pulled off by the cantilever with a pressing amount of 2 nm and a scanning speed of 10 Hz. This operation was carried out at 23°C. The force curve obtained by this operation was fitted based on the JKR theoretical formula to calculate the surface elastic modulus. For the surface elastic modulus, 4096 points were measured in 1 μm×1 μm on the surface of the peeling agent layer of the first peeling film, and the average of these values ​​was taken and rounded off to one decimal place to obtain the surface elastic modulus (MPa). The results are shown in Table 1.

[0242] [Table 1]

[0243]

[0244] [Second release film (light release film)]

[0245] “SP-PET 381130 (thickness: 38 μm)” manufactured by Lintec Corporation was used.

[0246] [Coating agent containing protective film-forming composition]

[0247] The following components were mixed at the blending ratio (solid content conversion) shown in Table 2, and diluted with methyl ethyl ketone so that the solid content concentration became 50% by mass to prepare a coating agent.

[0248] (A) Polymer component

[0249] (A-1) A (meth)acrylate copolymer (weight average molecular weight: 400,000, glass transition temperature: -1°C) prepared by copolymerization of 10 parts by mass of n-butyl acrylate, 70 parts by mass of methyl acrylate, 5 parts by mass of glycidyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate.

[0250] (A-2) A (meth)acrylate copolymer (weight average molecular weight: 450,000, glass transition temperature: 2° C.) prepared by copolymerizing 10 parts by mass of n-butyl acrylate, 65 parts by mass of methyl acrylate, 12 parts by mass of glycidyl methacrylate, and 13 parts by mass of 2-hydroxyethyl acrylate.

[0251] (B) Curable component (thermosetting component)

[0252] (B-1) Bisphenol A epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent weight 184 to 194 g / eq)

[0253] (B-2) Acrylic rubber microparticle-dispersed bisphenol A liquid epoxy resin (manufactured by Nippon Shokubai Co., Ltd., BPA328, epoxy equivalent weight 230 g / eq, acrylic rubber content 20 phr)

[0254] (B-3) Dicyclopentadiene epoxy resin (manufactured by DIC Corporation, EPICLON HP-7200HH, softening point 88-98°C, epoxy equivalent 255-260 g / eq)

[0255] (C) Curing agent: dicyandiamide (manufactured by Mitsubishi Chemical Corporation, DICY7)

[0256] (D) Curing accelerator: 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by SHIKOKU CHEMICALS CORPORATION, CUREZOL 2PHZ)

[0257] (E) Filling material

[0258] (E-1) Epoxy-modified spherical silica filler (manufactured by Admatechs, SC2050MA, average particle size 0.5 μm)

[0259] (E-2) Silica filler ("YC100C-MLA" manufactured by Admatechs, average particle size 0.1 μm)

[0260] (F) Silane coupling agent: γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403, methoxy equivalent weight: 12.7 mmol / g, molecular weight: 236.3)

[0261] (G) Colorant: Carbon black (manufactured by Mitsubishi Chemical Corporation, MA600B, average particle size 28 nm)

[0262] [Table 2]

[0263]

[0264] The prepared protective film-forming film composition was applied to the release-treated surface of the first release film (any of A to C described above) and dried at 100°C for 2 minutes to form a protective film-forming film with a thickness of 20 μm. A second release film was then attached to the protective film-forming film to obtain a three-layer protective film-forming sheet with release films formed on both sides of the protective film-forming film. The attachment conditions were a temperature of 60°C, a pressure of 0.4 MPa, and a speed of 1 m / min. The protective film-forming sheet was then cut to a width of 208 mm and wound up to a length of 50 meters to form a roll.

[0265] The following measurements and evaluations were performed using the obtained protective film-forming sheet.

[0266] [Adhesion between protective film-forming films]

[0267] The protective film-forming film was exposed from the protective film-forming sheet in the following manner, and the protective film-forming films were attached to each other to measure the adhesive force.

[0268] <Fixing the Protective Film Forming Film on the Adhesive Tape>

[0269] I. The second release film of the protective film-forming sheet having a three-layer structure of second release film / protective film-forming film / first release film is peeled off.

[0270] II. An adhesive tape manufactured by Lintec Corporation (product name PET50PL-SHIN: acrylic adhesive layer / 50 μm PET substrate) was attached to the exposed protective film-forming film at 23° C. to prepare a laminate sample of “PET substrate / acrylic adhesive layer / protective film-forming film / first release film”.

[0271] III. Cut the laminate sample into strips 25 mm wide and 250 mm long.

[0272] <Fixing the Protective Film-Forming Film on the SUS Plate>

[0273] I. A double-sided tape having a PET film as a core material was attached to the entire surface of a SUS plate (0.5 mm thick×70 mm×150 mm).

[0274] II. The second release film of the protective film-forming sheet having a three-layer structure of second release film / protective film-forming film / first release film is peeled off.

[0275] III. The exposed protective film-forming film was attached to the entire adhesive surface of the double-sided tape to obtain a laminate sample of "SUS plate / double-sided tape / protective film-forming film / first release film".

[0276] IV. The first release film is peeled off to expose the protective film-forming film.

[0277] <Measurement of Adhesion>

[0278] From a sample of the "PET substrate / acrylic adhesive layer / protective film-forming film / first release film" laminate, the first release film was peeled off to expose the protective film-forming film. The "PET substrate / acrylic adhesive layer / protective film-forming film" laminate and the "SUS plate / double-sided tape / protective film-forming film" laminate were stacked with the protective film-forming films facing each other and bonded using a 2 kg roller at 23°C.

[0279] The sheets were allowed to stand without heating, and after 2 minutes (±20 seconds) had passed since the application, the adhesion strength was measured by the following measurement method.

[0280] A universal tensile testing machine (manufactured by Shimadzu Corporation, product name

[0281] The peel force was measured using an AUTOGRAPH AG-IS ("AUTOGRAPH AG-IS") at a peel rate of 300 mm / min, a temperature of 23°C, and a peel angle of 180° over a measurement distance of 70 mm. The average of the measured values ​​over a distance of 50 mm, excluding the first and last 10 mm of the measurement distance, was taken as the "adhesion strength between protective film-forming films."

[0282] [Peeling force F1 when peeling the first peeling film from the protective film-forming film]

[0283] The second release film was peeled off from the resulting protective film-forming sheet. The exposed surface of the protective film-forming film was then attached to the good-adhesive surface of 25 μm-thick high-adhesive PET (PET25A-4100 manufactured by TOYOBO Co., Ltd.) by heat lamination (70°C, 1 m / min) to create a laminate sample. The laminate sample was cut into 100 mm widths to create a measurement sample. The back of the first release film of the measurement sample was secured to a rigid support plate using double-sided tape.

[0284] A universal tensile testing machine (manufactured by Shimadzu Corporation, product name

[0285] Using a 180° peel angle and a peel speed of 1 m / min, the protective film-forming film / high-adhesion PET composite (integrated) was peeled from the first release film using a 180° peel angle and a 1 m / min peel rate. The load applied during this process was measured. The total measurement distance was 100 mm, and the average of the measured values ​​over the entire 80 mm interval, excluding the first and last 10 mm, was taken as the peel force F1. The results are shown in Table 2.

[0286] [Peeling force F2 when peeling the second peeling film from the protective film-forming film]

[0287] The obtained protective film-forming sheet was cut into a width of 100 mm to prepare a measurement sample. The back surface of the first release film of the measurement sample was fixed to a hard support plate using a double-sided tape.

[0288] A universal tensile testing machine (manufactured by Shimadzu Corporation, product name

[0289] "AUTOGRAPH (registered trademark) AG-IS"), the second release film was peeled off from the measurement sample, and the load at this time was measured under the same conditions as when measuring the above F1, and was defined as the peel force F2.

[0290] The obtained peeling forces F1 and F2 were compared, and it was confirmed that F1 was greater than F2 for all the samples.

[0291] [Punching of protective film forming sheet and waste removal]

[0292] Using a RAD-3600F / 12 manufactured by Lintec Corporation, with specifications for 200mm wafers, the die was inserted from the second release film side of the protective film-forming sheet to punch out the protective film-forming film and the second release film into a circular shape (inner diameter of 198mm). At this point, a slit was made in the first release film using a partial punching method (punching process). Four dies with different blade widths were used to perform half-cuts of varying widths. Punching was performed 40 times.

[0293] After the punching process, the protective film sheet is moved between multiple rollers. The circular portion punched out remains on the first release film, and the second release film and the surrounding unused portion of the circular portion are removed (waste removal). At this point, the second release film, which has been completely cut by the punching process, is reattached with a long piece of adhesive tape and then removed.

[0294] <Incision Width>

[0295] After the waste material removal step, the protective film-forming sheet was cut along its thickness so that the cut portion of the first release film did not deform. The protective film-forming sheet was kept flat and the cross-section was observed using a scanning electron microscope (SEM, "VE-9800" manufactured by KEYENCE CORPORATION). The width of the cut remaining in the first release film at the interface between the first release film and the protective film-forming film was measured.

[0296] Select the 20th of the 40 circular segments and measure the width of the 20th segment at six equally spaced points on the circumference of the circle (connecting the points will form a regular hexagon). The minimum value among the six points is the "incision width." Round off to one decimal place.

[0297] The wider the cut width, the less the protective film-forming films adhere to each other, and the smoother the waste removal can be performed.

[0298] <Evaluation of waste removal performance>

[0299] During the waste removal process, the number of circular portions of the protective film-forming film that floated up along with the unnecessary portions was counted. The fewer the floating pieces, the less adhered the protective film-forming films were, and the smoother the waste removal process.

[0300] The above results are summarized in Table 3.

[0301] [Table 3]

[0302]

[0303] Table 3 confirms that when the adhesion between the protective film-forming films is 19 N or less, the protective film-forming films do not adhere to each other after the punching process, allowing for smooth waste removal. Furthermore, as shown in Example 7, as the kerf width becomes narrower, the protective film-forming films tend to adhere to each other after the punching process, preventing smooth waste removal.

[0304] Industrial Applicability

[0305] As described above, according to the present invention, a protective film-forming sheet and a method for producing the same can be provided, which can sufficiently suppress defects in scrap removal even when the slit width during punching is narrow.

Claims

1. A sheet for forming a protective film, which is a long sheet and comprises a curable protective film-forming film and a first release film provided on one surface of the protective film-forming film, wherein: The adhesion strength after two protective film-forming films were attached to each other at 23° C. with a load of 2 kgf for 2 minutes was 19 N / 25 mm or less.

2. The protective film-forming sheet according to claim 1, wherein The surface elastic modulus of the surface of the first release film in contact with the protective film-forming film is 17 MPa or less.

3. The protective film-forming sheet according to claim 1 or 2, wherein The protective film forming sheet has a cutout formed therein so that a portion of the protective film forming sheet has a predetermined closed shape when the protective film forming sheet is viewed from above. The incision penetrates the protective-film-forming film in the thickness direction of the protective-film-forming sheet and reaches a portion of the first release film.

4. The protective film-forming sheet according to claim 3, wherein The width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more.

5. A method for producing a punched protective film-forming sheet, comprising the step of forming a notch so that a portion of the protective film-forming sheet according to claim 1 or 2 has a predetermined closed shape. The incision penetrates the protective-film-forming film in the thickness direction of the protective-film-forming sheet and reaches a portion of the first release film.

6. The method for producing a punched protective film-forming sheet according to claim 5, wherein: The width of the cut at the interface between the protective film-forming film and the first release film is 8 μm or more.

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