Sheet for forming a protective film and method for processing the sheet for forming a protective film

Abstract

The present invention provides a sheet for forming a protective film and a method for processing the sheet for forming a protective film. Even when a protective film forming film is cut out using a cutting blade, the formation of lifting between the protective film forming film and the support film is suppressed. The sheet for forming a protective film has a protective film forming film and a first release film disposed on one main surface of the protective film forming film in a peelable manner. The probe tack value of the protective film forming film at 23°C is less than 6200 mN, and the surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C is 17 MPa or less, and the product of the probe tack value and the surface elastic modulus is 66000 or less.

Description

Technical Field

[0001] The present invention relates to a sheet for forming a protective film and a method for processing the sheet for forming a protective film. In particular, it relates to a sheet for forming a protective film that is not likely to generate floating that will become a starting point for peeling or leave marks on the protective film, and a method for processing the sheet for forming a protective film. Background Art

[0002] In recent years, semiconductor devices have been manufactured using an installation method called flip chip bonding. In this installation method, when installing a semiconductor chip having a circuit surface formed with convex electrodes such as bumps, the circuit surface side of the semiconductor chip is flipped (face down) and bonded to the chip mounting portion. Therefore, the semiconductor device has a structure in which the back side of the semiconductor chip on which no circuit is formed is exposed.

[0003] Therefore, in order to protect the semiconductor chip from impacts during handling or the like, a hard protective film made of an organic material is often formed on the back side of the semiconductor chip. Such a protective film is formed, for example, by curing after attaching a protective film forming film to the back side of a semiconductor wafer or formed in a non-cured state.

[0004] The protective film forming film and a support film that supports the protective film forming film together form a long strip-shaped sheet for forming a protective film. Before using the protective film forming film, the long strip-shaped sheet is usually wound into a roll. Moreover, when using the protective film forming film, the long strip-shaped sheet for forming a protective film unwound from the roll is cut into a shape substantially the same as that of the semiconductor wafer to be attached, and then attached to the semiconductor wafer.

[0005] Patent Document 1 discloses a long strip-shaped adhesive sheet having a first sheet and a second sheet provided on both sides of an adhesive layer. By punching the adhesive sheet, the adhesive layer is divided into a punched portion and a continuous waste portion, and a part of the adhesive layer of the punched portion and the first sheet in contact with the punched portion are separated from the adhesive sheet together. The punched portion is attached as an adhesive film to, for example, the back side of a semiconductor wafer.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2017 / 145735 Summary of the Invention

[0009] Technical Problem to be Solved by the Invention

[0010] When forming a film using a protective film, as described above, a protective film forming film having a predetermined shape is cut out from a protective film forming sheet. The cutting out of the protective film forming film generally uses a punching blade. In the cutting process using the punching blade, the punching blade enters the protective film forming film to cut the protective film forming film, and stops halfway to reach the support film. Then, by pulling out the punching blade, the protective film forming film inside the punching blade is completely separated from the protective film forming film outside the punching blade, and a protective film forming film having a closed shape is obtained.

[0011] However, in the cutting process, since the protective film forming film comes into contact with the punching blade, the protective film forming film easily adheres to the punching blade. Therefore, there is a problem that when the punching blade is pulled out, the protective film forming film near the punching blade is stretched and deformed in a state of adhering to the punching blade as the punching blade is pulled out, and is peeled off from the support film.

[0012] The portion where the protective film forming film is peeled off from the support film becomes floating. If such floating occurs, in the process of removing the protective film forming film outside the punching blade to obtain the protective film forming film inside the punching blade, when removing the protective film forming film outside, the floating becomes the starting point of peeling, and the protective film forming film inside that should remain is also accidentally peeled off and removed.

[0013] In addition, in the protective film forming film, traces caused by peeling are likely to appear on the surface of the portion peeled off from the support film. The surface of the protective film forming film that is in contact with the support film will be exposed to the outside after the protective film forming film is attached to the back surface of the wafer. Therefore, the portion where traces are formed due to peeling from the support film is also exposed to the outside. As a result, this trace causes poor appearance of the protective film.

[0014] In addition, since the above traces are formed when the protective film forming film is peeled off from the support film, there is a tendency that even if the protective film forming film is adhered to the support film again after peeling, the traces will not disappear and will remain.

[0015] In view of the above actual situation, the present invention aims to provide a protective film forming sheet and a method for processing the protective film forming sheet, which can suppress the formation of floating between the protective film forming film and the support film even when the protective film forming film is cut out using a cutting blade.

[0016] Technical means for solving technical problems

[0017] The solution of the present invention is as follows.

[0018] [1] A protective film forming sheet, which has a protective film forming film and a first release film disposed on one main surface of the protective film forming film in a peelable manner.

[0019] The probe tack value of the protective film forming film at 23°C is less than 6200 mN.

[0020] The surface elastic modulus of the surface of the first release film that contacts the protective film forming film at 23°C is 17 MPa or less.

[0021] The product of the probe tack value and the surface elastic modulus is 66000 or less.

[0022] [2] The sheet for forming a protective film according to [1], wherein the first release film has a substrate and a first release agent layer formed on one main surface of the substrate, and the first release agent layer contacts the protective film forming film.

[0023] [3] The sheet for forming a protective film according to [1] or [2], which has a second release film disposed on the other main surface of the protective film forming film in a peelable manner.

[0024] When the peeling force for peeling the first release film from the protective film forming film is set as F1 and the peeling force for peeling the second release film from the protective film forming film is set as F2, F1 and F2 satisfy the relationship of F1 > F2.

[0025] [4] The sheet for forming a protective film according to any one of [1] to [3], wherein the thickness of the first release agent layer is in the range of 30 nm or more and 200 nm or less.

[0026] [5] The sheet for forming a protective film according to any one of [1] to [4], wherein in the sheet for forming a protective film, a cut is formed in such a manner that a part of the sheet for forming a protective film has a specified closed shape when the sheet for forming a protective film is viewed from above.

[0027] The cut penetrates the protective film forming film in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film.

[0028] [6] The sheet for forming a protective film according to [5], wherein in the direction from the end surface of the protective film forming film having a closed shape toward the center of the protective film forming film, the maximum value of the distance between the end surface and the part where floating is observed between the protective film forming film and the first release film is less than 4 mm.

[0029] [7] A method for processing a sheet for forming a protective film, which has a step of forming a cut in such a manner that a part of the sheet for forming a protective film according to any one of [1] to [4] has a specified closed shape.

[0030] The cut penetrates the protective film forming film in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film.

[0031] Advantages of the Invention

[0032] According to the present invention, a sheet for forming a protective film and a method for processing the sheet for forming a protective film can be provided. Even when a protective film forming film is cut out using a cutting blade, the formation of lifting between the protective film forming film and the support film is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1A FIG. is a cross-sectional schematic view of an example of the sheet for forming a protective film according to this embodiment.

[0034] Figure 1B FIG. is a cross-sectional schematic view of another example of the sheet for forming a protective film according to this embodiment.

[0035] Figure 2A FIG. is a perspective view for explaining the process of forming a cut in a strip-shaped sheet for forming a protective film according to this embodiment.

[0036] Figure 2B FIG. is a cross-sectional schematic view of a strip-shaped sheet for forming a protective film in which a cut is formed.

[0037] Figure 2C FIG. is a cross-sectional schematic view of the sheet for forming a protective film after removing the protective film forming film other than the circular protective film forming film and the second release film from the strip-shaped sheet for forming a protective film in which a cut is formed.

[0038] Figure 3A FIG. is a cross-sectional schematic view for explaining the case where lifting is formed when the cutting blade is pulled out.

[0039] Figure 3B FIG. is a cross-sectional schematic view showing a laminate of a protective film forming film with lifting and a first release film.

[0040] Figure 3C FIG. is for showing Figure 3B a plan view of the laminate of the protective film forming film with lifting and the first release film as observed from the direction of the arrow shown.

[0041] Figure 3D FIG. is a cross-sectional schematic view for explaining the case where the formation of lifting is suppressed when the cutting blade is pulled out from the sheet for forming a protective film according to this embodiment.

[0042] Figure 4 FIG. is a cross-sectional schematic view showing that the first release film and the second release film have a first release agent layer and a second release agent layer.

[0043] Figure 5 FIG. is a perspective view of a strip-shaped sheet for forming a protective film in which a cut is formed and which is unreeled from a sheet roll of the sheet for forming a protective film according to this embodiment.

[0044] Figure 6ATo show the Figure 2C Schematic cross-sectional view of attaching the sheet for forming a protective film shown to a workpiece.

[0045] Figure 6B Schematic cross-sectional view of showing that the protective film forming film attached to the workpiece is protected by a protective film.

[0046] Explanation of reference numerals

[0047] 1: Sheet for forming a protective film; 10: Protective film forming film; 11: Circular protective film forming film; 12: Protective film forming film other than the circular protective film forming film; 20: First release film; 21: Substrate; 22: First release agent layer; 30: Second release film; 31: Substrate; 32: Second release agent layer; 40: Cut; 50: Cutting blade. Detailed description of the invention

[0048] Hereinafter, based on specific embodiments, the present invention will be described in detail with reference to the drawings.

[0049] First, the main terms used in this specification will be described.

[0050] The workpiece is a plate-like body to which a protective film forming film is attached and to be processed. As the workpiece, for example, a wafer and a panel can be cited. Specifically, a semiconductor wafer and a semiconductor panel can be cited. As a processed product of the workpiece, for example, a chip obtained by singulating a wafer can be cited. Specifically, a semiconductor chip obtained by singulating a semiconductor wafer can be exemplified. At this time, the protective film is formed on the back side of the wafer.

[0051] The "surface" of the workpiece refers to the surface on which convex electrodes such as circuits and bumps are formed, and the "back surface" refers to the surface on which no circuits or the like are formed.

[0052] 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.

[0053] In this specification, the weight ratio of the components constituting each composition is expressed as a solid component ratio.

[0054] (1. Sheet for forming a protective film)

[0055] As Figure 1A shown, the sheet 1 for forming a protective film of this embodiment has a configuration in which the first release film 20 that supports the protective film forming film 10 is disposed on one main surface 10a of the protective film forming film 10, and the second release film 30 is disposed on the other main surface 10b.

[0056] The sheet 1 for forming a protective film of this embodiment is not limited to Figure 1AThe structure shown. For example, the sheet for forming a protective film may also have a structure that does not have either the first release film or the second release film. Figure 1B The sheet 1 for forming a protective film having a structure in which a first release film 20 is disposed on one main surface 10a of the protective film forming film 10 is shown.

[0057] Hereinafter, although the sheet for forming a protective film having the Figure 1A structure shown is used for explanation, the following explanation also applies to the Figure 1B structure shown.

[0058] In the present embodiment, the sheet for forming a protective film is used to attach the protective film forming film to a workpiece. After the protective film forming film is attached to the workpiece, it is protected to form a protective film for protecting the workpiece or the processed product of the workpiece.

[0059] In the present embodiment, in order to attach the protective film forming film to the workpiece, a protective film forming film having a predetermined closed shape is cut out from the Figure 1A sheet 1 for forming a protective film shown. Specifically, a circular cut is formed from the second release film 30 side along the Figure 2A predetermined cutting position 40a on the sheet 1 for forming a protective film shown, thereby forming a circular protective film forming film. As Figure 2B shown, the cut 40 penetrates the second release film 30 and the protective film forming film 10 and reaches a part of the first release film 20, and is divided into a circular protective film forming film 11 and a protective film forming film 12 other than this.

[0060] Next, as Figure 2C shown, the second release film 30 and the protective film forming film 12 other than the circular protective film forming film 11 are removed from the sheet 1 for forming a protective film, thereby obtaining a circular protective film forming film 11 and a long strip-shaped first release film 20. The protective film forming film of this laminate is attached to the back surface of the workpiece, the first release film is peeled off, and the protective film forming film is protected.

[0061] As Figure 2A shown, the sheet 1 for forming a protective film is preferably a long strip-shaped sheet capable of forming a plurality of protective film forming films 11 to be attached to the workpiece. In addition, the sheet 1 for forming a protective film is also preferably a sheet roll formed by winding the long strip-shaped sheet. In addition, the sheet 1 for forming a protective film may also be a single sheet obtained by cutting a long strip-shaped sheet for forming a protective film into a single sheet capable of forming a protective film forming film 11 to be attached to the workpiece.

[0062] When forming the cut, after the protective film forming film comes into contact with the cutting blade for a short time, the cutting blade separates from the protective film forming film. At this time, since adhesiveness is generated on the protective film forming film, the protective film forming film easily adheres to the cutting blade. Therefore, as Figure 3AAs shown, when the cutting blade 50 is pulled out after cutting the protective film forming film 10, the protective film forming film 10 near the cutting blade 50 tends to be stretched and deformed in a state of adhering to the cutting blade 50 as the cutting blade 50 is pulled out. Then, finally, the protective film forming film 10 is peeled off from the first release film 20, and a bulge A is formed between the protective film forming film 10 and the first release film 20. The laminate of the protective film forming film 11 having the bulge A formed thereon and the first release film 20 is shown in Figure 3B . Figure 3C The bulge A formed in the laminate of the protective film forming film 11 and the first release film 20 when viewed from the direction of the arrow shown in Figure 3B is shown.

[0063] Such a bulge becomes the starting point for the protective film forming film to peel off from the first release film. Therefore, when the second release film 30 and the protective film forming film 12 other than the circular protective film forming film 11 are removed from the long strip-shaped first release film 20 after cutting out the protective film forming film, there is a situation where, although it is not originally a peeling process, the circular protective film forming film 11 may accidentally peel off from the first release film 20, and a part or all of the protective film forming film 11 is removed together with the second release film 30. If the protective film forming film 11 peels off, the protective film forming sheet 1 that should be attached to the workpiece does not exist and is transported to the next process, resulting in defective conditions.

[0064] In addition, in the protective film forming film, traces are likely to appear in the bulge peeled off from the first release film due to the pulling out of the cutting blade. For the surface of the protective film forming film that is in contact with the first release film, the opposite surface of this surface is attached to the back surface of the wafer and then the first release film is peeled off to expose this surface to the outside. Therefore, the bulge is also exposed to the outside. That is, since the traces are exposed to the outside, the protective film including the traces is judged to have a defective appearance.

[0065] In addition, since the above-mentioned traces are formed when the protective film forming film is peeled off from the first release film, there is a tendency that even if the protective film forming film is adhered to the first release film again after peeling, the traces will not disappear and will remain after the protective film is formed.

[0066] In contrast, since the protective film forming sheet of the present embodiment has the following characteristics, when the cutting blade is pulled out, the protective film forming film is not easily attached to the cutting blade, and the formation of a bulge can be suppressed. As a result, the accidental peeling of the protective film forming film 11 from the first release film 20 and the defective appearance of the protective film can be suppressed.

[0067] As Figure 3CAs shown in the figure, in the laminate of the protective film forming film 11 and the first release film 20 of the present embodiment, when the maximum value D of the distance from the end face of the protective film forming film 11 to the portion where the bulge A can be observed is less than 4 mm in the direction from the end face of the protective film forming film 11 toward the center O of the protective film forming film 11, it is determined that the formation of the bulge can be suppressed. Hereinafter, the constituent elements of the sheet 1 for forming a protective film will be described in detail.

[0068] (2. Protective film forming film)

[0069] As described above, after the protective film forming film is attached to the workpiece, it is made into a protective film to form a protective film for protecting the workpiece or the processed product of the workpiece.

[0070] "Making into a protective film" means making the protective film forming film into a state having sufficient characteristics for protecting the workpiece or the processed product of the workpiece. Specifically, when the protective film forming film is curable, "making into a protective film" means making the uncured protective film forming film into a cured product. In other words, the protective film forming film after being made into a protective film is a cured product of the protective film forming film, which is different from the protective film forming film.

[0071] After laminating the workpiece on the curable protective film forming film, by curing the protective film forming film, the protective film can be firmly adhered to the workpiece, and a protective film with durability can be formed.

[0072] On the other hand, when the protective film forming film does not contain a curable component and is used in an uncured state, at the moment when the protective film forming film is attached to the workpiece, the protective film forming film is made into a protective film. In other words, the protective film forming film after being made into a protective film is the same as the protective film forming film.

[0073] When high protective performance is not pursued, since it is not necessary to cure the protective film forming film, it is easy to use the protective film forming film.

[0074] In the present embodiment, it is preferable that the protective film forming film is curable. Therefore, it is preferable that the protective film is a cured product. As the cured product, for example, a thermoset product and an energy ray cured product can be exemplified. In the present embodiment, it is more preferable that the protective film is a thermoset product.

[0075] In addition, it is preferable that the protective film forming film has adhesiveness at normal temperature (23°C) or exhibits adhesiveness by heating. Thereby, when the workpiece is laminated on the protective film forming film, the two can be adhered. Therefore, positioning can be accurately performed before curing the protective film forming film.

[0076] The protective film forming film may be composed of one layer (single layer) or may be composed of two or more layers. When the protective film forming film has a plurality of layers, these plurality of layers may be the same as or different from each other, and there is no particular limitation on the combination of the layers constituting these plurality of layers.

[0077] In the present embodiment, it is preferable that the protective film forming film is a single layer. A single-layer protective film forming film can achieve high precision in thickness and is thus easy to produce. In addition, if the protective film forming film is composed of multiple layers, it is necessary to consider the adhesion between layers and the stretchability of each layer, and there is a risk of peeling from the adherend due to this. When the protective film forming film is a single layer, the above risk can be reduced, and the degree of freedom in design is also improved.

[0078] The thickness of the protective film forming film is not particularly limited, and it is preferably less than 100 μm, 70 μm or less, 45 μm or less, 30 μm or less. By setting the upper limit value of the thickness of the protective film forming film to the above value, it is possible to suppress the deformation of the protective film forming film near the cutting blade being stretched in a state of adhering to the cutting blade as the cutting blade is pulled out.

[0079] In addition, the thickness of the protective film forming film is preferably 5 μm or more, 10 μm or more, 15 μm or more. By setting the lower limit value of the thickness of the protective film forming film to the above value, it is easy to obtain the performance of protecting the workpiece as a protective film.

[0080] In addition, the thickness of the protective film forming film refers to the overall thickness of the 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 the layers constituting the protective film forming film.

[0081] (2.1 Probe adhesiveness value of the protective film forming film at 23°C)

[0082] In the present embodiment, the probe adhesiveness value of the protective film forming film at 23°C is less than 6200 mN. The probe adhesiveness value is an index of the adhesive force exhibited in a short time after contacting the adherend. As Figure 3D shown, by setting the probe adhesiveness value of the protective film forming film at 23°C within the above range, it is possible to suppress: the protective film forming film 10 coming into contact with the cutting blade 50 and strongly adhering, and when the cutting blade 50 is pulled out, the protective film forming film 10 being stretched and deformed in a state of adhering to the cutting blade 50. As a result, it is possible to suppress: the protective film forming film 10 being overstretched (deformed) and peeling from the first release film 20 to form a bulge.

[0083] The probe adhesiveness value of the protective film forming film at 23°C is preferably 5900 mN or less, 5400 mN or less, 4900 mN or less, 4400 mN or less, 4000 mN or less. In addition, the lower limit value of the probe adhesiveness value of the protective film forming film at 23°C is not particularly limited, but in the present embodiment, it is preferably 50 mN, 200 mN, 500 mN, 1000 mN. By setting the lower limit value of the probe adhesiveness value at 23°C to the above value, the applicable temperature range when attaching the protective film forming film to the workpiece is wide.

[0084] The probe tack value of the protective film-forming film at 23°C can be determined with reference to JIS Z0237:1991, Section 5, using a well-known probe tack test apparatus. That is, the probe tack value of the protective film-forming film at 23°C can be determined by the same method as described in JIS Z0237:1991, Section 5, but it can also be determined under conditions different from those described in JIS Z0237:1991, Section 5. The specific measurement method will be described in detail in the following examples.

[0085] (2.2 Composition for protective film-forming film)

[0086] As long as the protective film-forming film has the above physical properties, the composition of the protective film-forming film is not particularly limited. In the present embodiment, the composition for forming the protective film (composition for protective film-forming film) is preferably a resin composition containing at least a polymer component (A), a curable component (B), and a filler (E). The polymer component can be regarded as a component formed by polymerizing a polymerizable compound. In addition, the curable component is a component capable of undergoing a curing (polymerization) reaction. In addition, the polymerization reaction in the present invention also includes a polycondensation reaction.

[0087] In addition, the components contained in the polymer component sometimes also belong to the curable component. In the present embodiment, when the composition for protective film-forming film contains a component that belongs to both the polymer component and the curable component, it is regarded that the composition for protective film-forming film contains both the polymer component and the curable component.

[0088] (2.2.1 Polymer component)

[0089] The polymer component (A) gives the protective film-forming film film-forming property (film-forming ability), and at the same time provides appropriate tack, and effectively makes the protective film-forming film uniformly adhere to the workpiece. The weight average molecular weight of the polymer component is usually in the range of 50,000 to 2,000,000, preferably 100,000 to 1,500,000, and particularly preferably 200,000 to 1,000,000. As such a polymer component, for example, an acrylic resin, a urethane resin, a phenoxy resin, a silicone resin, a saturated polyester resin, etc. can be used, and an acrylic resin is particularly preferably used.

[0090] In addition, in this specification, unless otherwise specified, the "weight average molecular weight" refers to the polystyrene conversion value measured by gel permeation chromatography (GPC). The measurement based on this method can be carried out, for example, in the following manner: using a high-performance GPC device "HLC-8120GPC" manufactured by TOSOH CORPORATION, successively connecting high-performance chromatographic columns "TSK guardcolumn H XL -H", "TSK Gel GMH XL”, “TSK Gel G2000 H XL ” (All of the above are manufactured by TOSOH CORPORATION). Under the conditions of column temperature: 40 °C and inlet flow rate: 1.0 mL / minute, the detector was set as a differential refractometer.

[0091] As the acrylic resin, for example, an (meth)acrylate copolymer composed of (meth)acrylate monomers and structural units derived from (meth)acrylic acid derivatives can be mentioned. Here, as the (meth)acrylate monomer, (meth)acrylate alkyl esters having 1 to 18 carbon atoms in the alkyl group can be preferably mentioned. Specifically, (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid propyl ester, (meth)acrylic acid butyl ester, etc. can be mentioned. In addition, as the (meth)acrylic acid derivative, for example, (meth)acrylic acid, glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, etc. can be mentioned.

[0092] In the present embodiment, glycidyl (meth)acrylate or the like is preferably used to introduce a glycidyl group into the acrylic resin. The compatibility of the acrylic resin having a glycidyl group introduced therein with the epoxy resin as a thermosetting component described later is improved, and there is a tendency to easily obtain a protective film-forming film having stable properties (including probe adhesion value). In addition, in the present embodiment, in order to control the adhesiveness or tackiness to the workpiece, 2-hydroxyethyl (meth)acrylate or the like is preferably used to introduce a hydroxyl group into the acrylic resin.

[0093] The glass transition temperature of the acrylic resin is preferably -70 to 40 °C, -35 to 35 °C, -20 to 30 °C, -10 to 25 °C, -5 to 20 °C. By setting the lower limit value of the glass transition temperature of the acrylic resin to the above value, it is easy to reduce the tackiness of the protective film-forming film. In addition, by setting the upper limit value of the glass transition temperature of the acrylic resin to the above value, the tackiness of the protective film-forming film is moderately increased, the adhesive force between the protective film-forming film and the workpiece is increased, and the adhesive force between the protective film and the workpiece is moderately increased.

[0094] When the acrylic resin has m kinds (m is an integer of 2 or more) of structural units, the glass transition temperature of the acrylic resin can be calculated in the following manner. That is, when any non-repeating numbers from 1 to m are sequentially assigned to m kinds of monomers that are the sources of the structural units in the acrylic resin and named as “monomer m”, the glass transition temperature (Tg) of the acrylic resin can be calculated using the Fox formula shown below.

[0095] [Mathematical formula 1]

[0096]

[0097] In the formula, Tg is the glass transition temperature of the acrylic resin; m is an integer of 2 or more; Tgk is the glass transition temperature of the homopolymer of monomer m; Wk is the mass fraction of structural unit m derived from monomer m in the acrylic resin, where Wk satisfies the following formula.

[0098] [Mathematical formula 2]

[0099]

[0100] In the formula, m and Wk are the same as the aforementioned m and Wk.

[0101] As Tgk, the values described in a polymer data handbook (Polymer Data Handbook), an adhesion handbook (Adhesion Handbook), or Polymer Handbook, etc. can be used. For example, the Tgk of the homopolymer of methyl acrylate is 10 °C, the Tgk of the homopolymer of n-butyl acrylate is -54 °C, the Tgk of the homopolymer of methyl methacrylate is 105 °C, the Tgk of the homopolymer of 2-hydroxyethyl acrylate is -15 °C, the Tgk of the homopolymer of glycidyl methacrylate is 41 °C, and the Tgk of 2-ethylhexyl acrylate is -70 °C.

[0102] When the total weight of the composition for forming the protective film is set to 100 parts by mass, the content of the polymer component is preferably 5 to 80 parts by mass, 8 to 70 parts by mass, 10 to 60 parts by mass, 12 to 55 parts by mass, 14 to 50 parts by mass, 15 to 45 parts by mass. By making the content of the polymer component within the above range, it is easy to control the adhesiveness of the protective film-forming film, and thus it is easy to control the above-mentioned probe adhesiveness value.

[0103] (2.2.2 Thermosetting component)

[0104] The curable component (B) forms a hard protective film by curing the protective film-forming film. As the curable component, a thermosetting component, an energy ray curable component, or a mixture thereof can be used. When it is cured by irradiating energy rays, since the protective film-forming film contains a filler and a colorant, etc. described later, the light transmittance decreases. Therefore, for example, when the thickness of the protective film-forming film becomes thick, energy ray curing tends to be insufficient.

[0105] On the other hand, a thermosetting protective film-forming film can be sufficiently cured by heating even when the thickness becomes thick, and thus a protective film with high protective performance can be formed. In addition, by using a general heating device such as a heating oven, many protective film-forming films can be uniformly heated to be thermally cured.

[0106] Therefore, in this embodiment, it is desirable that the curable component is thermosetting. That is, the protective film-forming film is preferably thermosetting.

[0107] It is possible to determine whether the protective film-forming film is thermosetting in the following manner. First, the protective film-forming film at room temperature (23 °C) is heated to a temperature above room temperature, and then cooled to room temperature to produce the heated and cooled protective film-forming film. Then, when comparing the hardness of the heated and cooled protective film-forming film with the hardness of the protective film-forming film before heating at the same temperature, the case where the heated and cooled protective film-forming film is harder is judged that the protective film-forming film is thermosetting.

[0108] As the thermosetting component, for example, an epoxy resin, a thermosetting polyimide resin, an unsaturated polyester resin, and a mixture thereof are preferably used. The thermosetting polyimide resin refers to the general term for a polyimide precursor and a thermosetting polyimide that can form a polyimide resin by thermosetting.

[0109] The epoxy resin as the thermosetting component has the property of forming a three-dimensional network structure and forming a firm coating film when heated. As such an epoxy resin, various known epoxy resins can be used. In the present embodiment, the molecular weight (formula weight) of the epoxy resin is preferably 300 or more and less than 50000, 300 or more and less than 10000, 300 or more and less than 5000, 300 or more and less than 3000. In addition, the epoxy equivalent of the epoxy resin is preferably 50 to 5000 g / eq, more preferably 100 to 2000 g / eq, and further preferably 150 to 1000 g / eq.

[0110] Specifically, as the above epoxy resin, glycidyl ethers of phenols such as bisphenol A, bisphenol F, resorcinol, phenyl novolac, and cresol novolac can be cited; 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-type or alkyl glycidyl-type epoxy resins obtained by substituting the active hydrogen bonded to a nitrogen atom such as aniline isocyanurate with a glycidyl group; so-called alicyclic epoxides 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 which an epoxy group is introduced by oxidizing a carbon-carbon double bond in the molecule, for example. In addition, epoxy resins having a biphenyl skeleton, a dicyclohexadiene skeleton, a naphthalene skeleton, etc. can also be used.

[0111] When a thermosetting component is used as the curable component (B), it is preferable to use a curing agent (C) as an auxiliary agent at the same time. As a curing agent for epoxy resin, a heat-active latent epoxy resin curing agent is preferable. The "heat-active latent epoxy resin curing agent" refers to a type of curing agent that is not easily reactive with epoxy resin at room temperature (23 °C) and is activated by heating above a certain temperature and reacts with epoxy resin. For the activation method of the heat-active latent epoxy resin curing agent, there are: a method of generating active species (anions, cations) by a chemical reaction based on heating; a method of being stably dispersed in epoxy resin near room temperature and being compatible-dissolved with epoxy resin at high temperature and starting a curing reaction; a method of starting a curing reaction after dissolving a molecular sieve-encapsulated type of curing agent at high temperature; a method based on microcapsules, etc.

[0112] Among the exemplified methods, a method of being stably dispersed in epoxy resin near room temperature and being compatible-dissolved with epoxy resin at high temperature and starting a curing reaction is preferable.

[0113] As specific examples of the heat-active latent epoxy resin curing agent, various onium salts, diacid dihydrazide compounds, dicyandiamide, amine adduct curing agents, high-melting-point active hydrogen compounds such as imidazole compounds, etc. can be cited. These heat-active latent epoxy resin curing agents can be used alone or in combination of two or more. Dicyandiamide is particularly preferable in this embodiment.

[0114] In addition, as a curing agent for epoxy resin, phenolic resin is also preferable. As the phenolic resin, condensates of phenols such as alkylphenols, polyphenols, naphthols, etc. and aldehydes can be used without particular limitation. Specifically, phenol novolak resin, o-cresol novolak resin, p-cresol novolak resin, tert-butylphenol novolak resin, dicyclopentadiene cresol resin, poly(p-vinylphenol) resin, bisphenol A novolak resin, or their modified products, etc. can be used.

[0115] The phenolic hydroxyl groups contained in these phenolic resins can easily undergo an addition reaction with the epoxy groups of the above-mentioned epoxy resin by heating, thereby forming a cured product with high impact resistance.

[0116] With respect to 100 parts by mass of the epoxy resin, the content of the curing agent (C) is preferably 0.01 to 30 parts by mass, 0.1 to 20 parts by mass, 0.2 to 15 parts by mass, 0.3 to 10 parts by mass. By making the content range of the curing agent (C) within the above range, it is easy to obtain the performance of protecting the workpiece as a protective film.

[0117] When using dicyandiamide as the curing agent (C), it is further preferred to use a curing accelerator (D) simultaneously. As the curing accelerator, for example, imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole (imidazoles in which one or more hydrogen atoms are replaced by groups other than hydrogen atoms) are preferred. Among them, 2-phenyl-4,5-dihydroxymethylimidazole is particularly preferred.

[0118] Relative to 100 parts by mass of the epoxy resin, the content of the curing accelerator is preferably 0.01 to 30 parts by mass, 0.1 to 20 parts by mass, 0.2 to 15 parts by mass, or 0.3 to 10 parts by mass. By making the content range of the curing accelerator (D) within the above range, it is easy to obtain the performance of protecting the workpiece as a protective film.

[0119] When the total weight of the composition for forming the protective film is set to 100 parts by mass, the total content of the thermosetting component and the curing agent is preferably 3 to 80 parts by mass, 5 to 60 parts by mass, 7 to 50 parts by mass, 9 to 40 parts by mass, or 10 to 30 parts by mass. If the thermosetting component and the curing agent are blended in such a ratio, it is easy to obtain the performance of protecting the workpiece as a protective film.

[0120] (2.2.3 Energy ray curable component)

[0121] 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.

[0122] The energy ray curable component is a component that cures by irradiating energy rays, and it is a component for imparting film-forming properties, flexibility, etc. to the film for forming the protective film.

[0123] As the energy ray curable component, for example, compounds having an energy ray curable group are preferred. As such compounds, known compounds can be cited.

[0124] (2.2.4 Filler)

[0125] By making the film for forming the protective film contain a filler (E), it becomes easy to adjust the thermal expansion coefficient of the protective film obtained by protecting the film for forming the protective film. By making the thermal expansion coefficient close to that of the workpiece, the adhesion reliability with the workpiece is further improved. In addition, by making the film for forming the protective film contain a filler (E), it is easy to obtain a hard protective film and obtain the performance of protecting the workpiece, and furthermore, the moisture absorption rate of the protective film can be reduced.

[0126] The filler (E) can be either an organic filler or an inorganic filler, and from the perspective of shape stability at high temperatures such as 260°C, an inorganic filler is preferred.

[0127] As preferred inorganic fillers, for example, powders such as silica, alumina, talc, calcium carbonate, red iron oxide, silicon carbide, boron nitride, etc. can be cited; beads formed by spheroidizing these inorganic fillers; surface modifiers of these inorganic fillers; single crystal fibers of these inorganic fillers; glass fibers, etc. Among them, silica and surface-modified silica are preferred. The surface-modified silica is preferably surface-modified using a coupling agent, and more preferably surface-modified using a silane coupling agent.

[0128] The average particle size of the filler is preferably 0.02 to 10 μm, 0.05 to 5 μm, 0.10 to 3 μm.

[0129] By making the average particle size range of the filler within the above range, the operability of the composition for forming the protective film becomes good. As a result, the quality of the composition for forming the protective film and the protective film is easily stabilized.

[0130] In addition, unless otherwise specified, "average particle size" in this specification refers to the particle size (D50) at the cumulative value of 50% in the particle size distribution curve obtained by the laser diffraction scattering method.

[0131] When the total weight of the composition for forming the protective film is set to 100 parts by mass, the content of the filler is preferably 15 to 80 parts by mass, 30 to 75 parts by mass, 40 to 70 parts by mass, 45 to 65 parts by mass.

[0132] By making the lower limit value of the filler content the above value, it is easy to reduce the tackiness of the protective film, so it is easy to control the above-mentioned probe tack value. In addition, by making the upper limit value of the filler content the above value, the adhesion between the protective film and the workpiece is improved, and the adhesion between the protective film and the workpiece is moderately improved.

[0133] (2.2.5 Coupling Agent)

[0134] The protective film preferably contains a coupling agent (F). By containing the coupling agent, after the protective film is cured, the adhesion between the protective film and the workpiece can be improved without impairing the heat resistance of the protective film, and at the same time, the water resistance (humidity resistance) can be improved. As the coupling agent, from the perspective of its versatility and cost advantage, a silane coupling agent is preferred.

[0135] As the silane coupling agent, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(methacryloyloxypropyl)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, imidazole silane, etc. can be cited. These silane coupling agents can be used alone or in combination of two or more.

[0136] (2.2.6 Colorant)

[0137] The protective film forming film preferably contains a colorant (G). Thus, the back surface of a workpiece such as a chip can be shielded, and various electromagnetic waves generated inside the electronic device can be blocked, reducing the malfunction of the workpiece such as the chip. In addition, in the process of removing the protective film forming film on the outside of the punching blade from the first release film to obtain the protective film forming film on the inside of the punching blade on the first release film, it is possible to immediately judge by the naked eye whether the remaining protective film forming film on the inside has been accidentally peeled off and removed.

[0138] As the colorant (G), for example, known pigments such as inorganic pigments, organic pigments, and organic dyes can be used. In this embodiment, inorganic pigments are preferably used.

[0139] As the inorganic pigment, 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 cited. Among them, it is particularly preferable to use carbon black. If it is carbon black, electromagnetic waves in a wide wavelength range can be blocked.

[0140] The blending amount of the colorant (especially carbon black) in the protective film forming film may vary 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 blending amount of the colorant is preferably 0.01 to 10% by mass, 0.04 to 7% by mass, 0.07 to 4% by mass based on the total mass of the protective film forming film.

[0141] 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. If the average particle size of the colorant is within the above range, it is easy to control the light transmittance within the required range.

[0142] (2.2.7 Other additives)

[0143] Within the range that does not impair the effects of the present invention, the composition for forming a protective film may further contain, for example, a photoinitiator, a crosslinking agent, a plasticizer, an antistatic agent, an antioxidant, a gettering agent, a tackifier, a release agent, etc. as other additives.

[0144] Among them, it is preferable that the content of the release agent in the composition for forming a protective film is less than a specified amount. In the present embodiment, relative to the total mass of the protective film-forming film, the content of the release agent is preferably less than 0.00099% by mass. If the content of the release agent is too large, there is a tendency for the adhesion reliability between the protective film and the workpiece to decrease. As the release agent, for example, alkyd-based release agents, silicone-based release agents, fluorine-based release agents, unsaturated polyester-based release agents, polyolefin-based release agents, wax-based release agents can be exemplified.

[0145] (3. First release film)

[0146] The first release film is a film that can support the protective film-forming film in a peelable manner. When forming a cut in the protective film-forming sheet, the cut reaches a part of the first release film without penetrating the first release film. That is, when forming a cut in the protective film-forming sheet, the first release film is half cut.

[0147] The first release film may be composed of one layer (single layer) or two or more layers of substrates. From the perspective of controlling peelability, 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 not derived from the substrate may be formed on the surface of the substrate.

[0148] In the present embodiment, it is preferable that the first release film has a substrate and a first release agent layer. By having the first release agent layer, it is easy to control the physical properties of the surface of the first release film on which the first release agent layer is formed.

[0149] In addition, in the first release film, it is preferable that the first release agent layer is directly formed on the surface of the substrate. By directly forming the first release agent layer on the surface of the substrate, the production of the first release film becomes easy, and thus cost reduction can be achieved.

[0150] In the present embodiment, the first release agent layer is formed on the surface of the first release film on the protective film-forming film side. As Figure 4 shown, in the protective film-forming sheet 1, the first release film 20 has a substrate 21 and a first release agent layer 22, and the main surface 20b of the first release agent layer 22 is in contact with the main surface 10a of the protective film-forming film.

[0151] The thickness of the first release film is not particularly limited, but is preferably 30 μm or more and 100 μm or less. In addition, the thickness of the first release film is more preferably 40 μm or more, and further preferably 45 μm or more. In addition, the thickness of the first release film is more preferably 80 μm or less, and further preferably 70 μm or less.

[0152] By setting the lower limit value of the thickness of the first release film to the above value, when cutting out the protective film forming film with a cutting blade, it is possible to prevent the cutting blade from penetrating the first release film and cutting the first release film. In addition, before the protective film forming sheet is unwound and the protective film forming film is cut out and transported to the next process, the protective film forming sheet passes through rollers such as guide rollers in the device. By setting the upper limit value of the thickness of the first release film to the above value, it is possible to prevent the protective film forming film from peeling off from the first release film.

[0153] In addition, the thickness of the first release film refers to the thickness of the entire first release film. For example, the thickness of the first release film composed of multiple layers refers to the total thickness of all the layers constituting the first release film.

[0154] (3.1 Surface Elastic Modulus of the First Release Film at 23°C)

[0155] In the present embodiment, the surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C (hereinafter, also referred to as the surface elastic modulus of the first release film at 23°C) is 17 MPa or less. The surface elastic modulus is an index of the ease of surface deformation. As Figure 3D shown, by setting the surface elastic modulus of the first release film at 23°C within the above range, when the cutting blade 50 is pulled out, the surface 20b (for example, the first release agent layer) of the first release film 20 in contact with the protective film forming film easily follows the deformation of the protective film forming film 10. As a result, it is possible to suppress the protective film forming film 10 from peeling off from the first release film 20 and forming a floating state.

[0156] The surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C is preferably 15 MPa or less, 14 MPa or less, 13 MPa or less, 12 MPa or less. In addition, the lower limit value of the surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C is not particularly limited, but in the present embodiment, it is preferably 3 MPa or more, 4 MPa or more, 5 MPa or more.

[0157] The surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C can be measured using an atomic force microscope with a cantilever. That is, the cantilever is pressed against and pulled away from the surface of the first release film in contact with the protective film forming film to obtain a force curve. The obtained force curve is fitted using the formula of the JKR theory to calculate the elastic modulus, which is used as the surface elastic modulus of the present invention. The specific measurement method will be described in detail in the following examples.

[0158] In addition, in the present embodiment, the product of the probe tack value (mN) of the protective film forming film at 23°C and the surface elastic modulus (MPa) of the surface of the first release film in contact with the protective film forming film at 23°C is 66,000 or less. By making the product 66,000 or less, the formation of lifting due to the peeling of the protective film forming film from the first release film can be suppressed.

[0159] The product of the probe tack value (mN) of the protective film forming film at 23°C and the surface elastic modulus (MPa) of the surface of the first release film in contact with the protective film forming film at 23°C is preferably 60,000 or less, and more preferably 54,000 or less.

[0160] When the first release film has a substrate and a first release agent layer, as described above, the first release agent layer becomes the surface of the first release film in contact with the protective film forming film. Therefore, the surface elastic modulus of the first release agent layer may be within the above range.

[0161] In addition, in the present embodiment, in the protective film forming sheet, when the peeling force for peeling the first release film from the protective film forming film is set as F1 and the peeling force for peeling the second release film from the protective film forming film described later is set as F2, F1 and F2 satisfy the relationship of F1 > F2. By satisfying this relationship, when removing the second release film from the protective film forming sheet, the remaining protective film forming film 11 will not be removed together with the second release film, and it is easy to leave the protective film forming film 11 on the first release film.

[0162] Therefore, the first release film is a heavy release film and the second release film is a light release film.

[0163] In addition, F1 is preferably 50 mN / 100 mm or more, 70 mN / 100 mm or more, 90 mN / 100 mm or more, 110 mN / 100 mm or more, and preferably 130 mN / 100 mm or more. By making F1 within the above range, the formation of lifting due to the peeling of the protective film forming film from the first release film can be further suppressed.

[0164] In the present embodiment, F1 and F2 are load values measured using a tensile testing machine. The specific measurement method will be described in detail in the following examples.

[0165] Hereinafter, the case where the first release film has a substrate and a first release agent layer will be described.

[0166] (3.2 Substrate)

[0167] The substrate of the first release film is not particularly limited as long as it is a material that can support the protective film forming film before the protective film forming film is attached to the workpiece, and is usually composed of a film mainly made of a resinous material (hereinafter referred to as "resin film").

[0168] As specific examples of the resin film, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. can be used. In addition, crosslinked films of these films can also be used. Further, it can also be a laminated film of these films. In the present embodiment, from the viewpoints of environmental safety, cost, etc., polyethylene terephthalate film is preferred.

[0169] For the substrate, various additives such as colorants, flame retardants, plasticizers, antistatic agents, lubricants, fillers, etc. can be contained in the above resin film.

[0170] Regarding the thickness of the substrate, it is not particularly limited as long as it can appropriately function in each process of using the protective film forming sheet and is within the range of the thickness of the above first release film. The thickness of the substrate is preferably 30 μm or more and 100 μm or less. In addition, the thickness of the substrate is more preferably 40 μm or more, and further preferably 45 μm or more. In addition, the thickness of the substrate is more preferably 80 μm or less, and further preferably 70 μm or less.

[0171] (3.3 First release agent layer)

[0172] The first release agent layer imparts releasability to the first release film from the protective film forming film. The first release agent layer is not particularly limited as long as it is composed of a material that can impart releasability. In the present embodiment, the first release agent layer can be obtained by curing a composition for the first release agent layer containing silicone.

[0173] The thickness of the first release agent layer is not particularly limited, but is preferably 30 nm or more and 200 nm or less. In addition, the thickness of the first release agent layer is more preferably 50 nm or more, and further preferably 80 nm or more. In addition, the thickness of the first release agent layer is more preferably 180 nm or less.

[0174] By making the thickness of the first release agent layer within the above range, when the protective film forming film is attached to the workpiece, stable release performance can be exhibited.

[0175] (3.4 Composition for the first release agent layer)

[0176] In this embodiment, in the composition for the first release agent layer, for example, alkyd release agents, silicone release agents, fluorine release agents, unsaturated polyester release agents, polyolefin release agents, wax release agents can be cited, among which, silicone release agents are preferred. When the composition for the first release agent layer contains a silicone release agent, it preferably contains a silicone release agent and a heavy release additive.

[0177] (3.4.1 Silicone release agents)

[0178] As the silicone release agent, a silicone release agent blended with a silicone having a dimethylpolysiloxane as a basic skeleton can be used.

[0179] This silicone can be any one of addition reaction type, polycondensation reaction type, and energy ray curing type such as ultraviolet curing type and electron beam curing type, and addition reaction type silicone is preferred. The addition reaction type silicone has high reactivity and excellent productivity, and at the same time, compared with the polycondensation reaction type, it has the advantages of small change in release force after manufacturing and no curing shrinkage.

[0180] As specific examples of the addition reaction type silicone, organopolysiloxanes having 2 or more alkenyl groups having 2 to 10 carbon atoms such as vinyl, allyl, propenyl, and hexenyl at the terminal and / or side chain of the molecule can be cited. In addition, from the viewpoint of reducing the surface elastic modulus, it is preferred that the number of alkenyl groups in the addition reaction type silicone is small.

[0181] When the total weight of the composition for the first release agent layer (excluding the catalyst described later) is set to 100 parts by mass, the content of the silicone formed from dimethylpolysiloxane is preferably less than 100 parts by mass, less than 90 parts by mass, less than 80 parts by mass, less than 70 parts by mass.

[0182] When using this addition reaction type silicone, it is preferable to use a crosslinking agent and a catalyst at the same time.

[0183] As the crosslinking agent, for example, an organopolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms in 1 molecule can be cited.

[0184] As specific examples of the crosslinking agent, dimethylhydrogensilanyloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsilanyloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymer, trimethylsilanyloxy-terminated methylhydrogenpolysiloxane, poly(hydrogensilsesquioxane), etc. can be cited.

[0185] In addition, from the perspective of reducing the surface elastic modulus, it is preferable that the content of the crosslinking agent in the composition for the first release agent layer is small.

[0186] Examples of the catalyst include particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, olefin complexes of chloroplatinic acid, palladium, and platinum group metal compounds such as rhodium.

[0187] By using the above catalyst, the curing reaction of the composition for the first release agent layer can be carried out more effectively.

[0188] From the perspective of making the surface elastic modulus within the above range and making the peeling force F1 within the above range, when the total weight of the composition for the first release agent layer (excluding the catalyst) is set to 100 parts by mass, the content of the silicone-based release agent is preferably 30 to 100 parts by mass, 50 to 100 parts by mass.

[0189] (3.4.2 Double Peeling Additive)

[0190] The double peeling additive is used to increase the peeling force F1 for peeling the first release film from the film on which the protective film is formed. Examples of the double peeling additive include silicone resins and organosilanes such as silane coupling agents. Among them, it is preferable to use a silicone resin.

[0191] As the silicone resin, for example, it is preferable to use an MQ resin containing an M unit as a monofunctional siloxane unit [R3SiO 1 / 2 and a Q unit as a tetrafunctional siloxane unit [SiO 4 / 2 . In addition, 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 transfer, one or more of the three Rs in the M unit are preferably a hydroxyl group or a vinyl group, and more preferably a vinyl group.

[0192] When the total weight of the composition for the first release agent layer (excluding the catalyst) is set to 100 parts by mass, the content of the double peeling additive is preferably 0 to 50 parts by mass, 5 to 45 parts by mass, 10 to 40 parts by mass.

[0193] Among them, from the perspective of reducing the surface elastic modulus, it is preferable that the content of the silicone resin (especially the MQ resin) in the composition for the first release agent layer is small.

[0194] Within the range that does not impair the effects of the present invention, the composition for the first release agent layer may contain commonly used additives in the release agent layer. Examples of such additives include dyes and dispersants.

[0195] (4. Second Release Film)

[0196] The second release film is a film that can support the formation of the protective film in a peelable manner. When a cut is formed in the protective film forming sheet, the cut penetrates the second release film. When forming a laminate of the protective film forming film having a closed shape and the first release film, the second release film is removed together with the protective film forming film other than the protective film forming film having a closed shape.

[0197] The second release film may be composed of one layer (single layer) or two or more layers of base materials. From the perspective of controlling peelability, the surface of the base material may be subjected to a release treatment. That is, the surface of the base material may be modified, or a material not derived from the base material may be formed on the surface of the base material.

[0198] In addition, when forming the second release agent layer, the second release agent layer is formed on the surface of the second release film on the side of the protective film forming film. As Figure 4 shown, in the protective film forming sheet 1, the second release film 30 has a base material 31 and a second release agent layer 32, and the main surface 30b of the second release agent layer 32 is in contact with the main surface 10b of the protective film forming film.

[0199] The thickness of the second release film is not particularly limited, but is preferably 10 μm or more and 75 μm or less. In addition, the thickness of the second release film is more preferably 18 μm or more, and further preferably 24 μm or more. In addition, the thickness of the second release film is more preferably 60 μm or less, and further preferably 45 μm or less. From the perspective of making the peel force F2 and the peel force F1 satisfy F1 > F2 as described above, the thickness of the second release film is preferably equal to or less than the thickness of the first release film, and more preferably less than the thickness of the first release film.

[0200] In addition, the thickness of the second release film refers to the overall thickness of the second release film. For example, the thickness of the second release film composed of multiple layers refers to the total thickness of all the layers constituting the second release film.

[0201] (4.1 Base material)

[0202] The base material of the second release film can be appropriately selected from the materials exemplified as the base material of the first release film.

[0203] (4.2 Second release agent layer)

[0204] When the second release film has a second release agent layer, the second release agent layer is not particularly limited as long as it is composed of a material that can impart peelability. For example, similar to the first release agent layer, the second release agent layer can be obtained by curing a composition containing a silicone-based second release agent layer.

[0205] The composition for the second release agent layer can be selected from the materials exemplified in the composition for the first release agent layer as long as it satisfies the relationship between F1 and F2 described above. Among them, it is preferable that the content of the material exemplified as the heavy release additive is less than that in the composition for the first release agent layer or that it is not contained.

[0206] (5. Method for manufacturing a sheet for forming a protective film)

[0207] The method for manufacturing the sheet for forming a protective film of the present embodiment is not particularly limited, and a known method can be adopted. For example, first, a composition for a release agent layer (a composition for a first release agent layer and a composition for a second release agent layer) for forming a first release film and a second release film is prepared. In the present embodiment, from the viewpoint of adjusting the viscosity to improve the coatability on the substrate, it is preferable to coat a coating agent obtained by diluting the composition for the release agent layer containing the above respective components with a diluting solvent on the substrate.

[0208] Examples of the diluting 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 diluting solvents can be used alone or two or more of them can be used simultaneously.

[0209] The solid content concentration of the coating agent containing the composition for the first release agent layer is preferably 0.3 to 10% by mass, more preferably 0.5 to 5% by mass, and still more preferably 0.5 to 3% by mass. The solid content concentration of the coating agent containing the composition for the second release agent layer is the same as that of the coating agent containing the composition for the first release agent layer.

[0210] In the present embodiment, after coating a coating agent containing the composition for the first release agent layer on one surface of the substrate, the coating film is dried and cured to form a first release agent layer. Thereby, a first release film is obtained. The second release film can also be produced in the same manner.

[0211] Next, a composition for a protective film forming film for forming a protective film forming film is prepared. In the present embodiment, in the same manner as the composition for the release agent layer, it is preferable to coat a coating agent obtained by diluting the composition for the protective film forming film with a diluting solvent on the release film. The type of the diluting solvent may be the same as that of the composition for the release agent layer.

[0212] On the other hand, the solid content concentration of the coating agent containing the composition for the protective film forming film is preferably 20 to 80% by mass, more preferably 30 to 70% by mass.

[0213] In this embodiment, a coating agent containing a composition for forming a protective film is coated on the first release agent layer of the first release film or the second release agent layer of the second release film by a known method, and then heated and dried to form a coating film. Next, the second release agent layer of the second release film or the first release agent layer of the first release film is laminated on the coating film to produce a sheet for forming a protective film. In this embodiment, from the viewpoints of making the release force F1 within the above range and making F1 > F2, it is preferable to coat the coating agent containing the composition for forming a protective film on the first release agent layer of the first release film rather than on the second release agent layer.

[0214] As a coating method of the coating agent containing each composition, for example, spin coating method, spraying method, bar coating method, knife coating method, roll coating method, roll knife coating method, blade coating method, die coating method, gravure coating method can be exemplified.

[0215] (6. Method for manufacturing a device)

[0216] As an example of a method for manufacturing a device using the sheet for forming a protective film of this embodiment, a method for manufacturing a chip with a protective film obtained by processing a wafer with a protective film forming film attached thereto will be described.

[0217] First, as Figure 5 shown, the sheet for forming a protective film 1 is unrolled from the sheet roll of the sheet for forming a protective film 1 to prepare a long strip-shaped sheet for forming a protective film 1. Next, as Figure 5 and Figure 2B shown, using a cutting blade 50, a cut 40 is formed in the long strip-shaped sheet for forming a protective film, which penetrates the second release film 30 and the protective film forming film 10 and reaches a part of the first release film 20.

[0218] By forming the cut 40, a circular protective film forming film 11 can be obtained. In the sheet for forming a protective film 1, since the probe tack value of the protective film forming film at 23°C is less than 6200 mN, the surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C is 17 MPa or less, and the product of the probe tack value and the surface elastic modulus is 66000 or less, as Figure 3C shown, when the cutting blade 30 is pulled out, the formation of lifting caused by the peeling of the protective film forming film 10 from the first release film 20 can be suppressed. That is, in the circular protective film forming film 11, the maximum value D of the distance from the end face of the protective film forming film 11 to the part where lifting is observed is less than 4 mm. In addition, the trace of the protective film forming film 10 caused by the peeling of the protective film forming film 10 from the first release film 20 is also suppressed.

[0219] Therefore, after the incision is formed, when removing the second release film 30 and the release film forming films 12 other than the protective film forming film 11, the protective film forming film 11 will not be accidentally peeled off from the strip-shaped first release film 20 due to floating and removed. That is, as Figure 2C shown, it is easy to obtain a protective film forming sheet with the protective film forming film 11 remaining on the strip-shaped first release film.

[0220] Next, as Figure 6A shown, the protective film forming film 11 is attached to the back surface 60b of the wafer 60 as a workpiece. As Figure 6B shown, the first release film 20 is peeled off from the laminate and the protective film forming film 11 is made into a protective film 15. Next, the wafer with the protective film is singulated to obtain a chip with a protective film. In addition, the protective film can be formed after singulating the wafer.

[0221] Since the formation of floating on the protective film forming film can be suppressed, traces on the surface of the protective film are also suppressed. Therefore, a chip with a protective film with suppressed appearance defects of the protective film can be obtained.

[0222] (7. Modification Example)

[0223] In the above, although a protective film forming sheet having a configuration in which a first release film is disposed on one surface of the protective film forming film and a second release film is disposed on the other surface ( Figure 1A ) has been described, as described above, the protective film forming sheet may also have a configuration without the second release film ( Figure 1B ).

[0224] In addition, as Figure 2B shown, the protective film forming sheet of the present embodiment further includes a strip-shaped protective film forming sheet having a cutout and formed with a plurality of protective film forming films 11 to be attached to a workpiece ( Figure 2B ). In addition, it further includes a sheet roll formed by winding the strip-shaped protective film forming sheet. In addition, a single piece obtained by cutting the strip-shaped protective film forming sheet into a single piece that can form one protective film forming film 11 to be attached to a workpiece is also included in the protective film forming sheet of the present embodiment.

[0225] Furthermore, the protective film forming sheet of the present embodiment further includes a strip-shaped protective film forming sheet without a second release film, having a cutout and formed with a plurality of protective film forming films 11 to be attached to a workpiece; a sheet roll formed by winding the strip-shaped protective film forming sheet; and a single piece obtained by cutting the strip-shaped protective film forming sheet into a single piece that can form one protective film forming film 11 to be attached to a workpiece.

[0226] In addition, Figure 5In this case, although the protective film 11 to be attached to the workpiece is circular, it may be other shapes as long as it is a closed shape. As other shapes, for example, polygons such as triangles, ellipses, etc. can be exemplified. In addition, it is preferable that the closed shape corresponds to the shape of the workpiece.

[0227] As described above, the embodiments of the present invention have been described, but the present invention is not limited to any of the above-described embodiments and can be changed in various ways within the scope of the present invention.

[0228] Examples

[0229] Hereinafter, the invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0230] (Production of the first release film)

[0231] The following components were mixed at the blending ratio (in terms of solid content) shown in Table 1, and a coating agent containing a composition for the first release agent layer was prepared using a mixed solvent of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 1 / 1 (mass ratio)) at a solid content concentration of 2% by mass.

[0232] (α) Silicone release agent

[0233] (α-1) A silicone 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)

[0234] (α-2) Dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: X-62-1387, weight average molecular weight: 2000)

[0235] (β) Silicone resin

[0236] MQ resin having a vinyl group (manufactured by Dow Corning Toray Co., Ltd., SD-7292, solid content 71% by mass)

[0237] (γ) Catalyst

[0238] Platinum (Pt) catalyst (manufactured by Dow Corning Toray Co., Ltd., SRX-212, solid content 100% by mass)

[0239] A coating agent containing the prepared composition for forming the first release agent layer was coated on a PET film (manufactured by Mitsubishi Chemical Corporation, trade name: DIAFOIL (registered trademark) T-100, thickness: 50 μm) as a substrate so that the film thickness after heating and drying was 0.15 μm, and the first release agent layer was formed on the PET film to produce the first release film.

[0240] [Table 1]

[0241]

[0242] (Production of the second release film)

[0243] As the second release film, a film obtained by subjecting a PET film to a release treatment ("SP-PET381130" manufactured by Lintec Corporation, thickness 38 μm) was used.

[0244] (Production of the protective film-forming film)

[0245] The following components were mixed at the blending ratio (in terms of solid content) shown in Table 2, and diluted with methyl ethyl ketone so that the solid content concentration was 50% by mass to prepare a coating agent containing the composition for forming the protective film-forming film.

[0246] (A) Polymer component

[0247] (A-1) A (meth)acrylate copolymer obtained by copolymerizing 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 (weight average molecular weight: 400,000, glass transition temperature: -1 °C)

[0248] (A-2) A (meth)acrylate copolymer obtained 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 (weight average molecular weight: 450,000, glass transition temperature: 2 °C)

[0249] (B) Curing component (thermosetting component)

[0250] (B-1) Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent 184 - 194 g / eq)

[0251] (B-2) Acrylate rubber particle-dispersed bisphenol A liquid epoxy resin (manufactured by NIPPON SHOKUBAI CO., LTD., BPA328, epoxy equivalent 230 g / eq, acrylate rubber content 20 phr)

[0252] (B-3) Dicyclopentadiene-based epoxy resin (manufactured by DIC CORPORATION, EPICLON HP-7200HH, softening point 88 - 98 °C, epoxy equivalent 255 - 260 g / eq)

[0253] (C) Curing agent: Dicyandiamide (manufactured by Mitsubishi Chemical Corporation, DICY7)

[0254] (D) Curing accelerator: 2-Phenyl-4,5-dihydroxymethylimidazole (manufactured by SHIKOKU CHEMICALS CORPORATION, CUREZOL 2PHZ)

[0255] (E) Filler

[0256] (E-1) Epoxy group-modified spherical silica filler (manufactured by Admatechs, SC2050MA, average particle size 0.5 μm)

[0257] (E-2) Silica filler (manufactured by Admatechs, YC100C-MLA, average particle size 0.1 μm)

[0258] (F) Silane coupling agent: γ-Glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403, methoxy equivalent 12.7 mmol / g, molecular weight 236.3)

[0259] (G) Colorant: Carbon black (manufactured by Mitsubishi Chemical Corporation, MA600B, average particle size 28 nm)

[0260] The coating agent containing the prepared film-forming composition for the protective film was coated on the surface of the first release film on which the first release agent layer was formed, and dried at 100 °C for 2 minutes to form a protective film-forming film with a thickness of 20 μm. Then, the peeled surface of the prepared second release film was attached to the protective film-forming film to obtain a 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 / minute.

[0261] While cutting the obtained sheet for forming a protective film to a width of 320 mm, it is wound around a 3-inch-diameter hollow plastic core with a length of 10 m to form a sheet roll.

[0262] Next, the following measurements and evaluations are carried out.

[0263] (Probe tack value of the protective film forming film at 23°C)

[0264] Multiple single sheets each having a protective film forming film 11 formed thereon are obtained from the produced sheet for forming a protective film. The second release film is peeled off from two single sheets, and the protective film forming films are bonded to each other to obtain a laminate in which a first release film, two protective film forming films, and a first release film are laminated in this order. The first release film is peeled off from the obtained laminate, the second release film is peeled off from another single sheet, and the protective film forming films are bonded to each other to obtain a laminate in which a first release film, three protective film forming films, and a first release film are laminated in this order. The above operations are repeated a specified number of times to obtain a test specimen for measurement in which a first release film, a laminate of protective film forming films with a thickness of 800 μm ± 20 μm, and a first release film are laminated in this order.

[0265] One side of the first release film is peeled off from the obtained test specimen for measurement, and using a probe tack tester (stainless steel probe) manufactured by TESTER SANGYO CO,.LTD., the probe tack value of the protective film forming film surface is measured at 23°C. The probe is cleaned by wiping with methyl ethyl ketone before measurement.

[0266] The measurement conditions are as follows.

[0267] Contact load: 200 gf,

[0268] Contact speed: 10 mm / second,

[0269] Probe Area: 5 mmΦ,

[0270] Contact time: 1 minute,

[0271] Peeling speed: 10 mm / second.

[0272] Seven measurements are carried out on the protective film forming film surface by changing the contact position of the probe. The minimum and the second smallest values among the seven test values are removed. The average value of the remaining five test values is taken as the "probe tack value of the protective film forming film at 23°C" (mN). In addition, the tens digit of the measured value is rounded off. The results are shown in Table 2.

[0273] (Surface elastic modulus of the first release film at 23°C)

[0274] A silicon nitride cantilever (manufactured by Bruker Corporation, product 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, MultiMode8). The fabricated first release film was placed on the atomic force microscope, and the surface of the first release agent layer of the fabricated first release film was pressed and pulled away with a pressing amount of 2 nm and a scanning speed of 10 Hz using the set cantilever. The force curve obtained by this operation was fitted using the formula of the JKR theory to calculate the surface elastic modulus. The surface elastic modulus was measured at 4096 points in a 1 μm × 1 μm area on the surface of the first release agent layer of the first release film, and the average value of these values was rounded to one decimal place as the surface elastic modulus (MPa). The results are shown in Table 2.

[0275] (Peeling force F1 for peeling the first release film from the protective film forming film)

[0276] The second release film was peeled from the obtained protective film forming sheet. The good adhesion surface of a good adhesion PET (manufactured by TOYOBO Co., Ltd., PET25A - 4100) with a thickness of 25 μm was attached to the surface of the protective film forming film exposed by peeling using thermal lamination (70 °C, 1 m / minute) to fabricate a laminate sample. The laminate sample was cut into a width of 100 mm to fabricate a measurement sample. The back surface of the first release film of the measurement sample was fixed to a rigid support plate using double-sided tape.

[0277] Using a universal tensile testing machine (manufactured by Shimadzu Corporation, product name “AUTOGRAPH (registered trademark) AG - IS”), the composite (integral type) body of the protective film forming film / good adhesion PET was peeled from the first release film at a measurement distance of 100 mm, a peeling angle of 180°, and a peeling speed of 1 m / minute, and the load at this time was measured. The average value of the load between 80 mm excluding the load in the first 10 mm and the load in the last 10 mm of the measurement distance in the measured load was taken as the peeling force F1. The results are shown in Table 2.

[0278] (Peeling force F2 for peeling the second release film from the protective film forming film)

[0279] The obtained protective film forming sheet was cut into a width of 100 mm to fabricate a measurement sample. The back surface of the first release film of the measurement sample was fixed to a rigid support plate using double-sided tape.

[0280] Using a universal tensile testing machine (manufactured by Shimadzu Corporation, product name "AUTOGRAPH (registered trademark) AG-IS"), the second release film was peeled from the test sample at a measurement distance of 100 mm, a peeling angle of 180°, and a peeling speed of 1 m / min, and the load at this time was measured. The average value of the load between 80 mm excluding the load of the first 10 mm and the last 10 mm of the measurement distance in the measured load was used as the peeling force F2.

[0281] The obtained peeling forces F1 and F2 were compared, and it was confirmed that F1 of all the specimens was larger than F2.

[0282] (Punching process evaluation)

[0283] Using RAD-3600F / 12 manufactured by Lintec Corporation, the obtained sheet for forming a protective film was subjected to punching processing of the protective film forming film (a circle with an inner diameter of 298 mm) to obtain Figure 2B the laminate of the protective film forming film and the first release film shown. In the direction from the end face of the protective film forming film toward the center of the protective film forming film, the distance between the floating portion generated between the protective film forming film and the first release film and the end face was measured, and the maximum value was determined using the following criteria.

[0284] The results are shown in Table 2.

[0285] A... less than 1 mm

[0286] B... 1 or more and less than 2 mm

[0287] C... 2 or more and less than 4 mm

[0288] D... 4 mm or more

[0289]

[0290] From Table 2, it was confirmed that when the probe tack value of the protective film forming film at 23°C, the surface elastic modulus of the surface of the first release film in contact with the protective film forming film at 23°C, and the product of the probe tack value and the surface elastic modulus were within the above ranges, the formation of floating was suppressed.

Claims

1. A sheet for forming a protective film, which has a protective film forming layer and a first release film disposed on one main surface of the protective film forming layer in a peelable manner.

2. The probe tack value of the protective film forming layer at 23°C is less than 6200 mN.

3. The surface elastic modulus of the surface of the first release film in contact with the protective film forming layer at 23°C is 17 MPa or less.

4. The product of the probe tack value and the surface elastic modulus is 66000 mN·MPa or less.

2. The sheet for forming a protective film according to claim 1, wherein, The first release film has a substrate and a first release agent layer formed on one main surface of the substrate, and the first release agent layer is in contact with the protective film forming layer.

3. The sheet for forming a protective film according to claim 1, which has a second release film disposed on the other main surface of the protective film forming layer in a peelable manner. When the peeling force for peeling the first release film from the protective film forming layer is set as F1 and the peeling force for peeling the second release film from the protective film forming layer is set as F2, F1 and F2 satisfy the relationship of F1 > F2.

4. The sheet for forming a protective film according to claim 2, which has a second release film disposed on the other main surface of the protective film forming layer in a peelable manner. When the peeling force for peeling the first release film from the protective film forming layer is set as F1 and the peeling force for peeling the second release film from the protective film forming layer is set as F2, F1 and F2 satisfy the relationship of F1 > F2.

5. The sheet for forming a protective film according to claim 2, wherein, The thickness of the first release agent layer is in the range of 30 nm or more and 200 nm or less.

6. The sheet for forming a protective film according to claim 4, wherein, The thickness of the first release agent layer is in the range of 30 nm or more and 200 nm or less.

7. The sheet for forming a protective film according to any one of claims 1 to 6, wherein, In the sheet for forming a protective film, a cut is formed in such a manner that a part of the sheet for forming a protective film has a specified closed shape when the sheet for forming a protective film is viewed from above. The cut penetrates the protective film forming layer in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film.

8. The sheet for forming a protective film according to claim 7, wherein, In the direction from the end surface of the protective film forming layer having a closed shape toward the center of the protective film forming layer, the maximum value of the distance between the end surface and the portion where a bulge formed between the protective film forming layer and the first release film is observed is less than 4 mm.

9. A method for processing a sheet for forming a protective film, which has a step of forming a cut in such a manner that a part of the sheet for forming a protective film according to any one of claims 1 to 6 has a specified closed shape. The cut penetrates the protective film forming layer in the thickness direction of the sheet for forming a protective film and reaches a part of the first release film.

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