Method for manufacturing release film and semiconductor package

Abstract

A mold release film according to the present invention comprises a mold release layer and a base material layer, the mold release layer containing two or more polymers and satisfying at least one of (1) to (4). (1) The mold release layer includes a plurality of regions having different component ratios, and when the Raman spectroscopic measurements are performed for the plurality of different regions, different peak intensities are exhibited in at least some of the plurality of different regions. (2) The surface of the mold release layer has a recessed and protruding shape, and when the Raman spectroscopic measurements are performed for the protrusions and recesses, different peak intensities are exhibited in at least some of the protrusions and at least some of the recesses. (3) The difference in SP values of the at least two polymers is 0.3 or greater. (4) At least one polymer is a nitrile group-containing (meth)acrylic polymer.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a release film and a semiconductor package. [Background technology]

[0002] Semiconductor chips are typically sealed in resin to shield and protect them from the outside air, and mounted on a substrate as a molded product called a package. The molded product is manufactured by injecting a resin-containing encapsulant into a mold. The mold has multiple cavities, which are connected via runners that act as channels for the encapsulant. Furthermore, the mold structure and the addition of release agents to the encapsulant resin are designed to facilitate easy release of the molded product from the mold.

[0003] On the other hand, in response to the demand for smaller packages and more pins, packaging methods such as Ball Grid Array (BGA), Quad Flat Non-leaded (QFN), and Wafer-Level Chip Size Package (WL-CSP) are increasing. In the QFN method, a resin release film is placed inside the mold along the mold to ensure standoff and prevent burr formation due to the sealing material at the terminals. In the BGA and WL-CSP methods, a resin release film is placed along the mold to improve the release properties of the package from the mold, and the sealing material is injected into the film for molding (see, for example, Patent Document 1). The method of molding using a release film is called the "film-assisted molding method." [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-158242 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Using the above-mentioned release film may leave flow marks from the sealant on the surface of the molded package, which may degrade its appearance. To reduce these flow marks, it is possible to add fillers to the release layer of the release film. Furthermore, in recent years, a technology has been explored in which multiple packages are mounted on a substrate and then sealed together. In this case, since packages of various shapes exist on the substrate, excellent stretchability is required for the release film.

[0006] When the release film is stretched, the release layer also stretches to follow the stretch of the substrate. However, if the release layer cannot keep up, it may break, and the molded product may not come out of the mold or may be difficult to remove. In particular, in release films in which fillers are added to the release layer to reduce flow marks, the elongation rate of the release layer decreases, and the release layer tends to break easily.

[0007] In view of these circumstances, the object of this disclosure is to provide a release film that has excellent stretchability and can reduce flow marks of the sealing material on the surface of a semiconductor package, and a method for manufacturing a semiconductor package using this release film. [Means for solving the problem]

[0008] The following embodiments are included as means for solving the above problems. <1> It includes a release layer and a base layer, The release layer contains two or more polymers, A release film in which the difference in SP values ​​of at least two of the aforementioned polymers is 0.3 or more. <2> It includes a release layer and a base layer, The release layer contains two or more polymers, A release film in which at least one of the polymers is a nitrile group-containing (meth)acrylic polymer. <3> It includes a release layer and a base layer, The release layer contains two or more polymers, A release film that satisfies at least one of the following conditions (1) or (2). (1) The release layer has multiple regions with different component ratios, and when Raman spectroscopy is performed in these multiple different regions, each of the multiple different regions exhibits a different peak intensity. (2) The surface of the release layer has an uneven shape, and when Raman spectroscopy is performed on the convex and concave portions, different peak intensities are observed in at least a portion of the convex portions and at least a portion of the concave portions, respectively. <4> The difference in SP values ​​of at least two of the aforementioned polymers is 0.3 or more. <2> or <3> The release film described above. <5> At least one of the aforementioned polymers is a nitrile group-containing (meth)acrylic polymer. <1> or <3> The release film described above. <6> (1) or (2) below must be met <1> or <2> The release film described above. (1) The release layer has multiple regions with different component ratios, and when Raman spectroscopy is performed in these multiple different regions, each of the multiple different regions exhibits a different peak intensity. (2) The surface of the release layer has an uneven shape, and when Raman spectroscopy is performed on the convex and concave portions, different peak intensities are observed in at least a portion of the convex portions and at least a portion of the concave portions, respectively. <7> In at least a portion of the multiple different types of regions, or in at least a portion of the convex portion and at least a portion of the concave portion, the component ratio of the polymer is different. <3> or <6> The release film described above. <8> In at least a portion of the aforementioned different types of regions, or in at least a portion of the convex portion and at least a portion of the concave portion, the content of the nitrile group-containing (meth)acrylic polymer differs. <7> The release film described above. <9> At least a portion of the convex portion and the concave portion is formed by phase separation within the release layer. <3> or <6> The release film described above. <10> In a laser microscope, no interface is observed around the protrusion within the release layer. <3> or <6> The release film described above. <11> The peaks exhibiting different peak intensities are peaks originating from the nitrile group. <3> or <6> The release film described above. <12> The surface of the release layer has an uneven shape, and the peak intensity derived from nitrile groups in at least a portion of the protrusions is greater than the peak intensity derived from nitrile groups in at least a portion of the recesses. <3> or <6> The release film described above. <13> The surface of the release layer has an uneven shape, and the mass content of the nitrile group-containing (meth)acrylic polymer in at least a portion of the protrusions is greater than the mass content of the nitrile group-containing (meth)acrylic polymer in at least a portion of the recesses. <3> or <6> The release film described above. <14> The arithmetic mean roughness (Ra) of the outer surface of the release layer is 1.5 μm or less. <1> ~ <13> A release film as described in any one of the items. <15> The weight-average molecular weight (Mw) of the aforementioned polymer is 1.0 × 10⁻⁶ 5 That's all. <1> ~ <14> A release film as described in any one of the items. <16> At least one of the polymers is a polymer containing structural units derived from (meth)acrylonitrile monomer, In at least two of the polymers, the difference in the proportion of constituent units derived from (meth)acrylonitrile monomer is 1% by mass or more. <1> ~ <15> A release film as described in any one of the items. <17> The two or more polymers are (meth)acrylic polymers having structural units derived from (meth)acryloyl monomers. <1> ~ <16> A release film as described in any one of the items. <18> At least a portion of the polymer is crosslinked. <1> ~ <17> A release film as described in any one of the items. <19> The content of the most abundant polymer in the release layer is 95% by mass or less relative to the total content of the polymer. <1> ~ <18> A release film as described in any one of the items. <20> The base layer is a polyester film. <1> ~ <19> A release film as described in any one of the items. <21>The release film according to any one of <1> to <20>, wherein the thickness of the release layer is 1μm to 50μm. <22>The release film according to any one of <1> to <21>, wherein the release film is used for transfer molding or compression molding. <23>A method for manufacturing a semiconductor package, comprising performing a transfer molding process or a compression molding process using the release film according to any one of <1> to <22>.

Advantages of the Invention

[0009] According to the present disclosure, there are provided a release film having excellent stretchability and capable of reducing the flow marks of the sealing material on the surface of the conductor package, and a method for manufacturing a semiconductor package using this release film.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic cross-sectional view showing the configuration of the release film. [Figure 2] It is a photograph and an analysis graph by a laser microscope of the surface of the release layer. [Figure 3] It is a spectral result of component analysis of the discontinuous phase (island phase, convex portion) and the continuous phase (sea phase, concave portion) in Sample G2 of FIG. 2 by microscopic Raman spectroscopy. [Figure 4] It is a spectral result of component analysis of the discontinuous phase (island phase, concave portion) and the continuous phase (sea phase, convex portion) in Sample G3 of FIG. 2 by microscopic Raman spectroscopy. [Figure 5] It is a plan view showing the shape of a test piece used for measuring the elongation at break of the release film.

Embodiments for Carrying Out the Invention

[0011] The following describes in detail the forms for implementing this disclosure. However, this disclosure is not limited to the following embodiments. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit this disclosure.

[0012] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes, provided that the purpose of such process is achieved. In this disclosure, the numerical range indicated using "~" includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where, when observing the region in which the layer exists, it is formed not only over the entire region but also over only a portion of the region.

[0013] In this disclosure, the thickness of the release film or each layer constituting the release film can be measured by known methods. For example, it may be measured using a dial gauge or the like, or it may be measured from a cross-sectional image of the release film. Alternatively, the material constituting the layer may be removed using a solvent or the like, and the thickness may be calculated from the mass before and after removal, the density of the material, the area of ​​the layer, etc. If the thickness of the layer is not constant, the arithmetic mean of the values ​​measured at any five points shall be taken as the thickness of the layer. In this disclosure, "(meth)acrylic" means either or both acrylic and methacrylic, "(meth)acrylate" means either or both acrylate and methacrylate, and "(meth)acryloyl" means either or both acryloyl and methacryloyl. When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the sizes of the components are not limited thereto.

[0014] <Release film> The release film of this disclosure comprises a release layer and a base layer, wherein the release layer comprises two or more polymers, and satisfies at least one of the following (1) to (4). (1) The release layer has multiple regions with different component ratios, and when Raman spectroscopy is performed in these multiple different regions, each of the multiple different regions exhibits a different peak intensity. (2) The surface of the release layer has an uneven shape, and when Raman spectroscopy is performed on the convex and concave portions, different peak intensities are observed in at least a portion of the convex portions and at least a portion of the concave portions, respectively. (3) The difference in SP values ​​of at least two of the aforementioned polymers is 0.3 or more. (4) At least one of the polymers is a nitrile group-containing (meth)acrylic polymer.

[0015] In this disclosure, "polymer" means a high molecular weight component that does not contain organic fillers. Here, organic fillers are insoluble or sparingly soluble in organic solvents (e.g., toluene, methyl ethyl ketone, and ethyl acetate) that can be used to prepare release layer-forming compositions. Here, insoluble or sparingly soluble in organic solvents means that, in a gel fraction test in accordance with JIS K6769 (2013), the gel fraction after dispersing resin particles in an organic solvent such as toluene and holding at 50°C for 24 hours is 97% by mass or more.

[0016] In this disclosure, "different polymer types" means that the types of constituent monomers are different, or that the types of constituent monomers are the same, but the content of constituent units derived from at least one monomer differs by 1% by mass or more.

[0017] In this disclosure, "showing different peak intensities when Raman spectroscopy is performed" means that the intensity of the peak appearing at a certain position in the Raman spectrum obtained by Raman spectroscopy is different, and the difference in the presence or absence of a peak at a certain position is also included in the difference in peak intensity.

[0018] In this disclosure, "convex portion" and "concave portion" refer to regions that are relatively higher or lower than other regions in the thickness direction. For example, the reference plane may be a concave portion and a region higher than the reference plane may be a convex portion, or the reference plane may be a convex portion and a region lower than the reference plane may be a concave portion.

[0019] The release film of this disclosure, having the above configuration, exhibits excellent stretchability and enables a reduction in flow marks on the surface of the molded semiconductor package. The reason for this is not clear, but it is presumed to be as follows. The release film of this disclosure is not limited in any way by the following presumption.

[0020] As described in (1), the material has multiple regions with different component ratios, and when Raman spectroscopy is performed in these multiple regions, at least a portion of each region shows different peak intensities. This allows the polymers to aggregate in one region, increasing in density and causing it to partially bulge, forming an uneven surface on the release layer. The fact that there are regions that show different peak intensities when Raman spectroscopy is performed means that the component ratios of these regions showing different peak intensities are different. Furthermore, as described in (2), the surface of the release layer may have an uneven shape, and when Raman spectroscopy is performed on the convex and concave portions, at least a portion of the convex portions and at least a portion of the concave portions may show different peak intensities. Showing different peak intensities when Raman spectroscopy is performed on at least a portion of the convex portions and at least a portion of the concave portions means that when Raman spectroscopy is performed on at least a portion of the convex portions and at least a portion of the concave portions, they may show different peak intensities. If there are multiple convex portions, the peak intensities of each convex portion may be the same or different. If there are multiple concave portions, the peak intensities of each concave portion may be the same or different. Therefore, it is believed that the release film described in (1) or (2) can create irregularities on the surface of the release film without adding fillers to the release layer.

[0021] As one specific method for forming multiple regions with different component ratios, two or more polymers with an SP value difference of 0.3 or more are used, as described in (3). Polymers with an SP value difference of 0.3 or more have low compatibility, so they separate from each other, while polymers of the same type aggregate together, making it possible to obtain the release films of (1) and (2). In particular, as described in (4), if at least one of the polymers is a nitrile group-containing (meth)acrylic polymer, the nitrile group-containing (meth)acrylic polymers tend to aggregate together and form protrusions.

[0022] Conventional release films reduce flow marks from the encapsulant on the semiconductor package surface by adding fillers to the release layer to create irregularities on its surface. However, in such conventional release films, the release layer is prone to rupture starting from the fillers. Furthermore, conventional release films are difficult to stretch because they contain fillers.

[0023] In contrast, the release film of the present disclosure that satisfies at least one of (1) to (4) can produce surface irregularities without the addition of fillers, thus eliminating the need for filler addition or reducing the amount of filler, resulting in excellent elongation. Furthermore, because the release film of the present disclosure produces an irregular shape on its surface, flow marks of the encapsulant on the surface of the semiconductor package are reduced. Furthermore, the release film of this disclosure exhibits excellent release properties because it creates an uneven surface. In addition, since the release film of this disclosure does not require the addition of fillers, it is possible to suppress the occurrence of problems such as filler detachment. Therefore, the release film of this disclosure can form protrusions where no clear interface is observed. Protrusions where no clear interface is observed refer to areas where, when observed with a laser microscope, no particle interface is observed, as is the case when fillers are added.

[0024] As an example of a release film according to this disclosure, Figure 1 schematically shows the cross-sectional structure of a release film. As shown in Figure 1, the release film 30 includes a base layer 10 and a release layer 20. The release film 30 may have other layers. Examples of other layers include a second release layer, an anchoring improvement layer, an antistatic layer, a coloring layer, and the like.

[0025] [Release layer] The release layer contains at least two types of polymers. The difference in SP values ​​between at least two polymers contained in the release layer is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 0.8 or more. The upper limit of the difference in SP values ​​is not particularly limited, but it is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less.

[0026] In this disclosure, if the release layer contains two types of polymers, the difference in SP values ​​refers to the difference in SP values ​​between each polymer. If the release layer contains three or more types of polymers, the difference in SP values ​​refers to the difference in SP values ​​between the polymer with the highest SP value and the polymer with the lowest SP value among the polymers contained in the release layer.

[0027] The SP value is a solubility parameter derived from the substructure units of a chemical structural formula, and is a value obtained by the Fedors method.

[0028] The type of polymer is not particularly limited, and it is preferable to select it considering the tackiness, release properties, heat resistance, etc. of the release layer. Specifically, examples of polymers include (meth)acrylic polymers, silicones, urethane polymers, etc., which have constituent units derived from (meth)acryloyl monomers. It is preferable that at least one of the polymers is a (meth)acrylic polymer, and it is more preferable to use two or more (meth)acrylic polymers. The proportion of (meth)acrylic polymer in the total polymer is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, and may be 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more. The upper limit is not particularly limited, and the proportion may be 100% by mass, 95% by mass or less, 90% by mass or less, or 85% by mass or less.

[0029] The (meth)acrylic polymer may be a homopolymer or a copolymer, or a combination of both. Preferably, at least one of the (meth)acrylic polymers is a copolymer. The copolymer may contain constituent units derived from monomer A that does not have functional groups, or constituent units derived from monomer B that has functional groups.

[0030] Monomer A is preferably a monomer with a relatively low glass transition temperature (Tg) (for example, -20°C or lower). A monomer with a relatively low Tg is one in which the glass transition temperature is relatively low when a homopolymer is synthesized using that monomer. Examples of monomer A include butyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The copolymer may contain one constituent unit derived from monomer A alone, or a combination of two or more units.

[0031] When the copolymer contains constituent units derived from monomer A, the total content of constituent units derived from monomer A in the copolymer is preferably more than 50% by mass, more preferably 55% by mass or more, and even more preferably 60% by mass or more. Furthermore, the total content is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less.

[0032] Preferably, at least one polymer is a copolymer containing structural units derived from monomer B having a functional group. Examples of functional groups include carboxylic acid groups, hydroxyl groups, amide groups, and nitrile groups. The functional groups may be crosslinkable or non-crosslinkable. Examples of crosslinkable functional groups include carboxylic acid groups, hydroxyl groups, and amide groups, while examples of non-crosslinkable functional groups include nitrile groups. The copolymer may contain one structural unit derived from monomer B alone or in a combination of two or more units. It is more preferable that at least one polymer is a nitrile group-containing (meth)acrylic polymer.

[0033] A crosslinkable polymer having a crosslinkable functional group may be included in the release film, at least partially crosslinked. In this disclosure, the form in which the release film contains two or more polymers is also included when two or more polymers are crosslinked.

[0034] When a polymer is crosslinked, it is possible to analyze or estimate the polymer before crosslinking by decomposing the bonds at the crosslinking points. For example, if a polymer has hydroxyl groups and an isocyanate compound is used as the crosslinking agent, it is presumed that crosslinking occurs by forming urethane bonds, and these urethane bonds can be selectively decomposed by pyridine.

[0035] The crosslinked polymer is preferably a crosslinked (meth)acrylic polymer, and more preferably a crosslinked (meth)acrylic copolymer.

[0036] Examples of monomer B1 having a crosslinkable functional group include (meth)acrylic acid, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, and (meth)acrylamide. Examples of monomer B2 having a non-crosslinkable functional group include (meth)acrylonitrile.

[0037] The total content of constituent units derived from monomer B1 in at least one polymer is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, the total content is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0038] The total content of constituent units derived from monomer B2 in at least one polymer is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. Furthermore, the content is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0039] Preferably, at least one of the polymers is a copolymer containing structural units derived from a monomer having a nitrile group, and more preferably, a copolymer containing structural units derived from a (meth)acrylonitrile monomer. The polymer used in combination may be a homopolymer that does not contain structural units derived from a monomer having a nitrile group, or it may be a copolymer that does not contain structural units derived from a monomer having a nitrile group.

[0040] In a copolymer containing structural units derived from monomers having nitrile groups, the content of structural units derived from monomers having nitrile groups is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. Furthermore, the content is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0041] In a copolymer containing constituent units derived from monomers having nitrile groups, the total content of constituent units derived from monomer A is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. Furthermore, the total content is preferably 94% by mass or less, more preferably 92% by mass or less, and even more preferably 90% by mass or less.

[0042] In a copolymer containing constituent units derived from monomers having nitrile groups, the total content of constituent units derived from monomer B1 is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, the total content is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0043] In copolymers that do not contain constituent units derived from monomers having nitrile groups, the total content of constituent units derived from monomer A is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. Furthermore, the total content is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less.

[0044] In a copolymer that does not contain structural units derived from monomers having nitrile groups, the total content of structural units derived from monomer B1 is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. Furthermore, the total content is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0045] In at least two polymers, the difference in the proportion of the structural units derived from the (meth)acrylonitrile monomer is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. The upper limit of the difference in the proportion of the structural units derived from the (meth)acrylonitrile monomer is not particularly limited, but is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0046] Preferred combinations of the two (meth)acrylic polymers include, for example, the following (I) and (II), and (I) is preferred. (I) A combination of a nitrile group-containing (meth)acrylic polymer and a (meth)acrylic polymer不含nitrile group (II) Both are nitrile group-containing (meth)acrylic polymers, and the content rates of the structural units derived from the (meth)acrylonitrile monomer are different from each other.

[0047] The number average molecular weight (Mn) of the polymer may be, for example, 1.0×10 3 or more, and may be 1.0×10 4 or more, and may be 1.0×10 5 or more, and may be 1.2×10 5 or more. Also, for example, it may be 1.0×10 6 or less, and may be 5.0×10 5 or less. The weight average molecular weight (Mw) of the polymer may be, for example, 1.0×10 3 or more, and may be 1.0×10 4 or more, and may be 1.0×10 5 or more, and may be 3.0×10 5 or more, and may be 5.0×10 5 or more. Also, for example, it may be 5.0×10 6 or less, and may be 1.0×10 6 or less. The Mn and Mw of the polymer are measured by a usual method using GPC (gel permeation chromatography).

[0048] The content of the most abundant polymer in the release layer is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, relative to the total polymer content. When the content of the most abundant polymer is 95% by mass or less, there is a tendency for irregularities to form on the surface of the release film.

[0049] When the polymer is a crosslinked polymer, it is preferable to use a crosslinking agent. Examples of known crosslinking agents include isocyanate compounds, melamine compounds, and epoxy compounds. Furthermore, from the viewpoint of forming a gently expanding network structure, it is more preferable that the crosslinking agent be a polyfunctional crosslinking agent such as a trifunctional or tetrafunctional agent.

[0050] The isocyanate crosslinking agent is not particularly limited and can be selected from known compounds having isocyanate groups (isocyanate compounds). From the viewpoint of reactivity, difunctional isocyanate compounds (compounds having two isocyanate groups) and polyfunctional isocyanates (compounds having three or more isocyanate groups) are preferred, and polyfunctional isocyanate compounds are more preferred.

[0051] Examples of bifunctional isocyanate compounds include aliphatic diisocyanate compounds, alicyclic diisoanate compounds, aromatic diisocyanate compounds, carbodiimide-modified products of these diisocyanate compounds, and polymeric compounds containing these diisocyanate compounds in their molecules.

[0052] Examples of aliphatic diisocyanate compounds include 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, and norbornane diisocyanate methyl (NBDI).

[0053] Examples of alicyclic diisocyanate compounds include transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), and H12-MDI (hydrogenated MDI).

[0054] Examples of aromatic diisocyanate compounds include dimer acid diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethylxylene diisocyanate (TMXDI), tollidine diisocyanate (TODI), and 1,5-naphthalene diisocyanate (NDI).

[0055] Examples of polyfunctional isocyanate compounds include trimers of difunctional isocyanate compounds and polymeric compounds that contain trimers of difunctional isocyanate compounds in their molecules. Examples of trimers of difunctional isocyanate compounds include isocyanurates, adducts, and biuretes.

[0056] The amount of crosslinking agent contained in the release layer may be, for example, 0.1 to 50 parts by mass or 1 to 40 parts by mass per 100 parts by mass of solids of the polymer contained in the release layer.

[0057] The release layer may contain, as needed, anchoring enhancers, crosslinking accelerators, colorants, antistatic agents, etc. For example, if the release layer contains an antistatic agent, discharge is less likely to occur during peeling, and electrostatic discharge damage to electronic components is suppressed.

[0058] Preferably, the release layer has multiple regions with different component ratios, and when Raman spectroscopy is performed in these multiple regions, at least a portion of each region exhibits different peak intensities. Furthermore, it is preferable that the surface of the release layer has an uneven shape, and when Raman spectroscopy is performed in the convex and concave portions, at least a portion of the convex portions and at least a portion of the concave portions exhibit different peak intensities. As an example, the component ratio of the polymer may differ in at least a portion of several different types of regions, or in at least a portion of the convex parts and at least a portion of the concave parts. More specifically, it is preferable that the content of the nitrile group-containing (meth)acrylic polymer differs in at least a portion of several different types of regions, or in at least a portion of the convex parts and at least a portion of the concave parts. Furthermore, it is preferable that the peaks showing different peak intensities are peaks originating from the nitrile groups.

[0059] In the release layer, it is preferable that at least one region contains a nitrile group-containing (meth)acrylic polymer, while the other region may or may not contain a nitrile group-containing (meth)acrylic polymer. From the viewpoint of making it easier to create irregularities on the surface of the release layer, it is preferable that the other region does not contain a nitrile group-containing (meth)acrylic polymer. Whether or not a region contains a nitrile group-containing (meth)acrylic polymer can be confirmed by performing a component analysis of that region using micro-Raman spectroscopy, as described later, and checking that no spectral peak corresponding to a nitrile group is detected.

[0060] Each region may exhibit a phase separation state within the layer when the surface of the release layer is observed in plan view, forming a continuous phase and a discontinuous phase. The area ratio of the continuous phase to the discontinuous phase can be adjusted by the blending ratio of the polymers contained in the release layer. Polymers with a low content in the release layer are included in the discontinuous phase, and polymers with a high content are included in the continuous phase.

[0061] Furthermore, it is preferable that the surface of the release layer has an uneven shape, and that the peak intensity derived from nitrile groups in at least a portion of the protrusions is greater than the peak intensity derived from nitrile groups in at least a portion of the recesses. Moreover, it is preferable that the surface of the release layer has an uneven shape, and that the mass content of nitrile group-containing (meth)acrylic polymer in at least a portion of the protrusions is greater than the mass content of nitrile group-containing (meth)acrylic polymer in at least a portion of the recesses.

[0062] Raman spectroscopy measurements in each region and on the uneven areas will be performed using a Raman spectrometer. For example, a Thermo Fischer Scientific "DXR2xi" will be used as the Raman spectrometer, and the measurements will be performed under the following conditions. ·Wavelength: 532nm Output: 10mW Exposure time: 0.05 seconds • Number of scans: 1000 • Aperture: 25μm pinhole • Objective lens: 100x

[0063] The component ratios in each region and uneven area are measured by obtaining a spectrum at each point irradiated with a laser using Raman spectroscopy. For example, the peaks in the Raman spectrum for specific components (e.g., nitrile groups) that make up the release layer are identified in advance, and the relative content of that specific component in one location and another location is confirmed based on the signal intensity.

[0064] Figure 2 shows a laser microscope photograph and analysis graph of the surface of the release layer. A VK-X3000 laser microscope manufactured by Keyence Corporation was used, with a 50x objective lens for observation. While Figure 2 uses the aforementioned laser microscope, other laser microscopes may be used to examine the surface of the release layer.

[0065] In Figure 2, sample G1 is a conventional release layer containing fillers, while samples G2 and G3 are release layers according to the present disclosure that use a nitrile group-containing (meth)acrylic polymer (polymer A) and a nitrile group-free (meth)acrylic polymer (polymer B) in combination. In sample G2, polymer A accounts for 15% by mass and polymer B accounts for 85% by mass of the total polymer. In sample G3, polymer A accounts for 85% by mass and polymer B accounts for 15% by mass of the total polymer.

[0066] The first and second rows of Figure 2 are planar photographs of the surface of the release layer observed from a planar perspective, and the third row is a cross-sectional curve that analyzes the surface irregularities along the straight line indicated by the arrow in the second row of the photograph. As shown in Figure 2, in samples G2 and G3, the release layer is formed in multiple regions.

[0067] In sample G2, the content of nitrile group-containing (meth)acrylic polymer in the total polymer is less than half, and in this case, the area of ​​the raised portion occupies less than half of the total polymer surface. On the other hand, in sample G3, the content of nitrile group-containing (meth)acrylic polymer in the total polymer is more than half, and in this case, the area of ​​the raised portion occupies more than half of the total polymer surface. From this, it can be seen that the content of nitrile group-containing (meth)acrylic polymer is higher in the raised portion compared to the recessed portion.

[0068] As shown in Figure 2, the conventional sample G1 exhibits low uniformity in terms of the shape and size of the protrusions due to the aggregation of fillers.

[0069] Figure 3 shows the spectral results obtained by micro-Raman spectroscopy for the discontinuous phase (island phase, convex areas) and continuous phase (sea phase, concave areas) of sample G2 in Figure 2. Here, the discontinuous phase refers to regions that occupy a small area on the observation surface, and the continuous phase refers to regions that occupy a large area on the observation surface.

[0070] In Figure 3, peaks originating from nitrile groups are detected in the discontinuous phase (convex portion), while no peaks originating from nitrile groups are detected in the continuous phase (concave portion). This result indicates that the polymer component ratios differ between the discontinuous phase (convex portion) and the continuous phase (concave portion). Furthermore, it can be seen that the convex portion contains a higher amount of nitrile group-containing (meth)acrylic polymer than the concave portion.

[0071] Figure 4 shows the spectral results of component analysis performed by micro-Raman spectroscopy on the convex (sea phase, continuous phase) and concave (island phase, discontinuous phase) of sample G3 in Figure 2. While peaks originating from nitrile groups are detected in the convex areas, no such peaks are detected in the concave areas. This indicates that the polymer component ratios differ between the convex and concave areas. Furthermore, the convex areas contain a higher content of nitrile group-containing (meth)acrylic polymer than the concave areas. In Figure 4, nitrile group-containing (meth)acrylic polymer is present as the main component in the total polymer at a concentration exceeding 50% by mass, forming a continuous phase, which in turn forms convex portions. In Figure 3, the continuous phase forms concave portions, whereas in Figure 4, the opposite is true. However, in both Figure 3 and Figure 4, the content of nitrile group-containing (meth)acrylic polymer is higher in the convex portions than in the concave portions.

[0072] The thickness of the release layer is not particularly limited, but is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. When the thickness of the release layer is 1 μm or more, sufficient adhesion to the electronic components is obtained, and the penetration of the encapsulating material is effectively suppressed. The thickness of the release layer may be 50 μm or less, or 25 μm or less. When the thickness of the release layer is 50 μm or less, thermal shrinkage stress during the heat curing of the release layer is less likely to occur, and the flatness of the release film is more easily maintained. In addition, if the release film has a conductive layer, the surface resistivity is kept low by not having the release layer surface too far from the conductive layer, and electrostatic discharge damage to electronic components is effectively suppressed. Considering factors such as ease of forming the release layer (applicability, etc.) and ensuring adhesive strength, the thickness of the release layer is preferably 1 μm to 50 μm, and more preferably 3 μm to 25 μm.

[0073] From the viewpoint of maximizing the effects of the embodiments of this disclosure, it is preferable that the release layer does not contain fillers, but it may contain fillers. If fillers are used, they may be at least one of organic fillers and inorganic fillers. The filler content may be, for example, 1 volume% or less, 0.5 volume% or less, or 0.1 volume% or less in the release layer. The filler content (volume %) in the release layer can be calculated based on the density and specific gravity of the resin components and filler, as measured by the Archimedes method.

[0074] (Elongation at break of the release layer) The elongation at break of the release layer is preferably 100% or more, more preferably 120% or more, and even more preferably 150% or more. The elongation at break of the release layer can be adjusted, for example, by the amount of nitrile group-containing (meth)acrylic polymer blended, if the release layer contains at least one type of nitrile group-containing (meth)acrylic polymer. The upper limit of the elongation at break of the release layer is not particularly limited and may be, for example, 800% or less, 500% or less, or 300% or less.

[0075] The elongation at break (%) of the release layer of a release film is measured as follows. First, a test specimen is prepared using the release film in the shape shown in Figure 5. A tensile test is performed by gripping both ends of this test specimen with a testing machine. The measurement is performed under conditions of 170°C, with a tensile speed of 200 mm / min. The elongation at break of the release layer is calculated from the gauge length A of the sample before the test (length of the part of the test specimen with a width of 10 mm as shown in Figure 5: 40 mm) and the gauge length B when the release layer breaks, using the following formula.

[0076]

number

[0077] For measuring the elongation at break of the release layer of a release film, for example, the "Tensilon Tensile Tester RTA-100" manufactured by Orientec Co., Ltd., the "Tensilon Universal Tester RTG-1210" manufactured by A&D Co., Ltd., or a similar tester equipped with a gripping device should be used.

[0078] (Surface roughness of the release layer) The arithmetic mean roughness (Ra) of the outer surface of the release layer (the surface opposite to the surface facing the substrate layer) is preferably 0.2 μm or more, more preferably 0.25 μm or more, and even more preferably 0.3 μm or more. The upper limit of the arithmetic mean roughness (Ra) is not particularly limited and may be, for example, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, or less than 1.0 μm.

[0079] The arithmetic mean roughness (Ra) of the outer surface of the release layer can be obtained by analyzing the results of measurements taken using a surface roughness measuring device (e.g., Kosaka Laboratory Co., Ltd., model SE-3500) under the conditions of a stylus tip diameter of 2 μm, a feed rate of 0.5 mm / s, and a scanning distance of 8 mm, according to JIS B0601 (1994) or ISO 4287 (1997). The arithmetic mean roughness (Ra) of the outer surface of the release layer can be adjusted by the blending ratio of polymers contained in the release layer, the thickness of the release layer, the amount of crosslinking agent used if one is used, and the amount of catalyst used if one is used.

[0080] [Base material layer] The base layer is not particularly limited and can be appropriately selected from base layers used in the relevant art. From the viewpoint of improving conformability to the shape of the mold, it is preferable to use a resin-containing base layer with excellent stretchability. The base layer should preferably have heat resistance above the heating temperature (approximately 100°C to 200°C) required for molding the sealant. Furthermore, from the viewpoint of suppressing the occurrence of wrinkles, tears, etc., when attaching the release film to the mold and when the sealant flows, it is preferable to select the material of the base layer considering the elastic modulus and elongation during heating.

[0081] The base material is preferably a polyester resin from the viewpoint of heat resistance and elastic modulus when heated. Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, and polybutylene terephthalate resin, as well as copolymers and modified resins thereof.

[0082] The base layer is preferably in the form of a sheet, preferably a sheet formed from polyester resin, more preferably a polyester film, and from the viewpoint of conformability to the mold, a biaxially oriented polyester film is preferred.

[0083] The thickness of the substrate layer is not particularly limited, but is preferably 5 μm to 200 μm, and more preferably 10 μm to 100 μm. When the thickness is 5 μm or more, it is easy to handle and tends to be less prone to wrinkling. When the thickness is 200 μm or less, it is easy to follow the mold during molding, which tends to suppress the occurrence of wrinkles in the molded semiconductor package.

[0084] [Other configurations] Depending on the material of the base layer, it is preferable to design the release sheet to facilitate peeling from the mold. For example, the surface of the base layer opposite to the release layer, i.e., the surface of the base layer facing the mold, may be given a textured finish or another release layer (second release layer) may be provided. The material of the second release layer is not particularly limited as long as it satisfies the requirements for release from the mold, heat resistance, etc., and the same material as the above-mentioned release layer (hereinafter also referred to as the "specific release layer") may be used. The thickness of the second release layer is not particularly limited, but is preferably 0.1 μm to 100 μm.

[0085] Furthermore, if necessary, an anchoring-enhancing layer, an antistatic layer, a colored layer, etc., may be provided between the specific release layer and the base material layer, between the base material layer and the second release layer, etc.

[0086] <Method for manufacturing release film> The release film of this disclosure can be manufactured by known methods. For example, the release film of this disclosure can be manufactured by applying a release layer forming composition to a substrate layer and drying it. The release layer forming composition comprises at least two of the above-mentioned polymers and may further comprise other resin components and other components that may be added as desired.

[0087] [Preparation of release layer forming composition] The method for preparing the release layer-forming composition is not particularly limited, and known composition preparation methods can be used. The solvent used for preparing the release layer-forming composition is not particularly limited, but it is preferably an organic solvent capable of dissolving the polymer. Examples of organic solvents include toluene, methyl ethyl ketone, and ethyl acetate.

[0088] [Granting and drying] The method for applying the release layer-forming composition to the substrate layer is not particularly limited, and known coating methods such as roll coating, bar coating, and kiss coating can be used. The amount of release layer-forming composition applied is preferably adjusted appropriately so that the thickness of the composition layer formed after drying is close to the desired thickness of the release layer (for example, 1 μm to 50 μm). The method for drying the applied release layer-forming composition is not particularly limited, and known drying methods can be used. For example, drying at 50°C to 150°C for 0.1 to 60 minutes may be used.

[0089] <Applications of release film> The release film of this disclosure is used when sealing semiconductor chips with an encapsulant. The release film of this disclosure is preferably used in transfer molding or compression molding.

[0090] By using the release film of this disclosure, it is possible to easily remove the semiconductor package (molded product) from the mold while minimizing damage to the semiconductor package. Furthermore, by using the release film of this disclosure, flow marks of the encapsulant on the surface of the semiconductor package (molded product) are suppressed, resulting in excellent uniformity of appearance. Moreover, even when used in situations where the release film requires stretchability, the rupture of the release layer is suppressed, so even in such usage scenarios, it is possible to easily remove the semiconductor package (molded product) from the mold while minimizing damage to the semiconductor package.

[0091] <Manufacturing method for semiconductor packages> In the semiconductor package manufacturing method of this disclosure, a transfer molding process or a compression molding process is performed using the release film of the present invention.

[0092] In the semiconductor package manufacturing method, first, the aforementioned release film of this disclosure is placed in the mold of a molding apparatus, and the release film is made to conform to the shape of the mold. Methods for making the release film conform to the shape of the mold include vacuum suction.

[0093] Then, the semiconductor chip is sealed with an encapsulant inside a mold with a release film that follows it. By sealing the semiconductor chip with an encapsulant while the semiconductor chip and release film are positioned inside the mold, a semiconductor package can be manufactured. After the semiconductor package is manufactured, the mold is opened and the molded semiconductor package is removed.

[0094] In the semiconductor package manufacturing method of this disclosure, since the release film of this disclosure is used, flow marks of the encapsulating material on the surface of the semiconductor package are suppressed, and a semiconductor package with excellent uniformity of appearance can be obtained. Furthermore, even when used in situations where the release film requires stretchability, the rupture of the release layer is suppressed, making it possible to easily remove the semiconductor package from the mold while minimizing damage to the semiconductor package.

[0095] Examples of semiconductor chips used in the above method include semiconductor elements, capacitors, terminals, etc. The type of encapsulant used in the above method is not particularly limited and examples include resin compositions containing epoxy resin, acrylic resin, etc. [Examples]

[0096] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to these examples.

[0097] (Synthesis of synthetic resins 1-4) Synthetic resins 1 to 4 were obtained by copolymerizing the monomers shown in Table 1 in the amounts (parts by mass) shown in Table 1 by solution polymerization. For the obtained synthetic resins 1-4, the number-average molecular weight Mn and weight-average molecular weight Mw were measured using gel permeation chromatography (GPC) on a standard polystyrene basis. Table 1 shows the SP values ​​for the obtained synthetic resins 1 to 4.

[0098] [Table 1]

[0099] The monomers in Table 1 represent the following: BA: Butyl acrylate · 4-HBA: 4-hydroxybutyl acrylate • MMA: Methyl methacrylate ·2-HEA: 2-hydroxyethyl acrylate · 2-HEMA: 2-hydroxyethyl methacrylate AN: Nitrile Acrylate

[0100] <Example 1> A release layer-forming composition was prepared by adding 20 parts by mass of Coronate L (Nippon Polyurethane Industries Co., Ltd., trade name) as a crosslinking agent to toluene in a total mixture of 100 parts by mass of synthetic resin 1 (85 parts by mass) and synthetic resin 3 (15 parts by mass) to a toluene solution with a solid content of 15% by mass. A biaxially oriented polyethylene terephthalate film (Unitika Ltd.: S-38) with a thickness of 38 μm was used as the base layer and subjected to corona treatment. Subsequently, the release layer-forming composition was applied to one side of the base layer using a roll coater and dried to form a release layer so that the average thickness after drying was 20 μm, thereby obtaining a release film.

[0101] <Example 2> A release film was prepared in the same manner as in Example 1, except that the average thickness of the release layer after drying was set to 10 μm.

[0102] <Example 3> A release film was prepared in the same manner as in Example 1, except that the average thickness of the release layer after drying was set to 5 μm.

[0103] <Example 4> A release film was prepared in the same manner as in Example 3, except that synthetic resin 1 (90 parts by mass) and synthetic resin 3 (10 parts by mass) were used.

[0104] <Example 5> A release film was prepared in the same manner as in Example 3, except that the total blending amount of synthetic resin 1 (80 parts by mass) and synthetic resin 3 (20 parts by mass) was 100 parts by mass, and the amount of crosslinking agent was 10 parts by mass.

[0105] <Example 6> A release film was prepared in the same manner as in Example 3, except that the total blending amount of synthetic resin 1 (80 parts by mass) and synthetic resin 3 (20 parts by mass) was 100 parts by mass, and the amount of crosslinking agent was 30 parts by mass. <Example 7> A release film was prepared in the same manner as in Example 3, except that synthetic resin 1 (50 parts by mass) and synthetic resin 3 (50 parts by mass) were used.

[0106] <Example 8> A release film was prepared in the same manner as in Example 3, except that synthetic resin 1 (20 parts by mass) and synthetic resin 3 (80 parts by mass) were used.

[0107] <Example 9> A release film was prepared in the same manner as in Example 3, except that synthetic resin 1 (10 parts by mass) and synthetic resin 3 (90 parts by mass) were used.

[0108] <Example 10> A release film was prepared in the same manner as in Example 3, except that synthetic resin 1 (80 parts by mass) and synthetic resin 4 (20 parts by mass) were used.

[0109] <Example 11> A release film was prepared in the same manner as in Example 3, except that the total blending amount of synthetic resin 1 (80 parts by mass) and synthetic resin 4 (20 parts by mass) was 100 parts by mass, and the amount of crosslinking agent was 30 parts by mass.

[0110] <Example 12> A release film was prepared in the same manner as in Example 3, except that the total blending amount of synthetic resin 1 (50 parts by mass) and synthetic resin 4 (50 parts by mass) was 100 parts by mass, and the amount of crosslinking agent was 20 parts by mass.

[0111] <Example 13> A release film was prepared in the same manner as in Example 3, except that the total blending amount of synthetic resin 1 (20 parts by mass) and synthetic resin 4 (80 parts by mass) was 100 parts by mass, and the amount of crosslinking agent was 20 parts by mass.

[0112] <Example 14> A release film was prepared in the same manner as in Example 3, except that the amount of crosslinking agent was 2.2 parts by mass for a total blend of 100 parts by mass of synthetic resin 3 (22 parts by mass) and synthetic resin 4 (78 parts by mass).

[0113] <Comparative Example 1> A release film was prepared in the same manner as in Example 3, except that the total blending amount of synthetic resin 1 (80 parts by mass) and synthetic resin 2 (20 parts by mass) was 100 parts by mass, and the amount of crosslinking agent was 10 parts by mass.

[0114] <Comparative Example 2> A release film was prepared in the same manner as in Example 3, except that 40 parts by mass of a crosslinking agent and 15 parts by mass of MX-500 (Sokken Chemical Co., Ltd., trade name, acrylic particles, average particle size 5 μm) as filler were added to 100 parts by mass of synthetic resin 2.

[0115] <Comparative Example 3> A release film was prepared in the same manner as in Example 3, except that the amount of crosslinking agent was 10 parts by mass per 100 parts by mass of synthetic resin 1.

[0116] <Comparative Example 4> A release film was prepared in the same manner as in Example 3, except that the amount of crosslinking agent was 20 parts by mass per 100 parts by mass of synthetic resin 3.

[0117] <Evaluation Test> (Surface roughness of the release layer (Ra)) The surface roughness (Ra) of the release layer of the release film was measured using the method described above. A "Surface Roughness Measuring Instrument SE-3500" manufactured by Kosaka Research Institute Co., Ltd. was used for the measurement. The results are shown in Table 2.

[0118] (Elongation at break of the release layer) The elongation at break of the release layer at 170°C was measured using the method described above. An Orientec Co., Ltd. "Tensilon Tensile Testing Machine RTA-100" was used for the measurement. The results are shown in Table 2.

[0119] (Evaluation of release properties against EMC) As an indicator of the release properties of the release film after molding with the sealing material, the peeling force was measured when a peel test was conducted at a peeling angle of 180° and a peeling speed of 1000 mm / min. The results were evaluated according to the following criteria. The results are shown in Table 2.

[0120] -Evaluation Criteria- A: Less than 150mN / 50mm B: 150mN / 50mm or more, 250mN / less than 50mm C:250mN / 50mm or more

[0121] (Evaluation of release layer fracture) A stainless steel plate (50 mm wide, 0.6 mm thick) was placed on the base layer side of the release film. Teflon (registered trademark) was placed on the release layer side, and a sealant (Resonac Co., Ltd.: product name "CEL-9750ZHF10") was sprayed between the release layer and the Teflon. Furthermore, the release film was placed so that the release layer side was in contact with the sealant, and a heat and pressure treatment at 170°C and 12.6 MPa was performed for 5 minutes. The molded packages were cut using a "KPS-4002 desktop hand cutter" manufactured by Sun Advance Co., Ltd., and then cast with epoxy resin. The cast packages were polished using abrasive paper with grit sizes P800, P1500, and P2200 to expose the cross-section. The polished package cross-sections were observed using a "VHX-7000 digital microscope" manufactured by Keyence Corporation to check for rupture of the release layer. The results are shown in Table 2.

[0122] (Evaluation of flow traces) The release layer side of the release film was placed in contact with the sealing material (Resonac Co., Ltd.: product name "CEL-9750ZHF10"), and a heat and pressure treatment at 180°C and 32 MPa was performed for 5 minutes. The package after treatment was visually inspected to check for the presence or absence of flow marks from the sealing material. The results are shown in Table 2.

[0123] [Table 2]

[0124] The values ​​for synthetic resins, crosslinking agents, and fillers in Table 2 represent the amount (parts by mass) used.

[0125] As shown in the results in Table 2, the release films of Examples 1 to 14 had an Ra value equal to or greater than that of the release film of Comparative Example 2, which had fillers added, and had an uneven surface shape. As shown in the results in Table 2, the release films of Examples 1 to 14 exhibited superior elongation, no rupture of the release layer, and better evaluation of flow marks compared to the release films of Comparative Examples 1 to 4. [Explanation of Symbols]

[0126] 10 Base material layer 20 Adhesive layer 30 Adhesive Films

Claims

1. It includes a release layer and a base layer, The release layer contains two or more polymers, The difference in SP values ​​of at least two of the aforementioned polymers is 0.3 or more. A release film in which the weight-average molecular weight (Mw) of the polymer is 5.0 × 10⁵ or greater.

2. It includes a release layer and a base layer, The release layer contains two or more polymers, At least one of the aforementioned polymers is a nitrile group-containing (meth)acrylic polymer. A release film in which the weight-average molecular weight (Mw) of the polymer is 5.0 × 10⁵ or greater.

3. It includes a release layer and a base layer, The release layer contains two or more polymers, The following conditions must be met: A release film in which the weight-average molecular weight (Mw) of the polymer is 5.0 × 10⁵ or greater. (1) The release layer has multiple regions with different component ratios, and when Raman spectroscopy is performed in these multiple different regions, each of the multiple different regions shows a different peak intensity. (2) The surface of the release layer has an uneven shape, and when Raman spectroscopy is performed on the convex and concave portions, different peak intensities are observed in at least a portion of the convex portions and at least a portion of the concave portions, respectively.

4. It includes a release layer and a base layer, The release layer contains two or more polymers, The following conditions must be met: (1) The release layer has multiple types of regions with different component ratios, and at least a portion of the multiple different types of regions is formed by phase separation within the release layer, and when Raman spectroscopy is performed in the multiple different types of regions, at least a portion of the multiple different types of regions each shows different peak intensities. (2) The surface of the release layer has an uneven shape, and at least a portion of the convex and concave portions are formed by phase separation within the release layer, and when Raman spectroscopy is performed on the convex and concave portions, at least a portion of the convex portions and at least a portion of the concave portions show different peak intensities, A release film in which the peaks exhibiting the aforementioned different peak intensities are peaks originating from nitrile groups.

5. It includes a release layer and a base layer, The release layer contains two or more polymers, The surface of the release layer has an uneven shape, and when Raman spectroscopy is performed on the convex and concave portions, different peak intensities are observed in at least a portion of the convex portion and at least a portion of the concave portion, respectively. The peaks exhibiting the aforementioned different peak intensities are peaks originating from the nitrile group. A release film in which, when viewed under a laser microscope, no interface is observed around the protrusions within the release layer.

6. The release film according to any one of claims 2 to 5, wherein the difference in SP values ​​of at least two of the aforementioned polymers is 0.3 or more.

7. The release film according to claim 1 or claim 3, wherein at least one of the polymers is a nitrile group-containing (meth)acrylic polymer.

8. The release film according to any one of claims 3 to 5, wherein the component ratio of the polymer differs in at least a portion of the multiple different types of regions, or in at least a portion of the convex portion and at least a portion of the concave portion.

9. The release film according to claim 3 or claim 4, wherein the content of the nitrile group-containing (meth)acrylic polymer differs in at least a portion of the multiple different types of regions, or in at least a portion of the convex portion and at least a portion of the concave portion.

10. The release film according to claim 5, wherein the content of the nitrile group-containing (meth)acrylic polymer differs in at least a portion of the convex portion and at least a portion of the concave portion.

11. The release film according to any one of claims 3 to 5, wherein the surface of the release layer has an uneven shape, and the peak intensity derived from nitrile groups in at least a portion of the protrusions is greater than the peak intensity derived from nitrile groups in at least a portion of the recesses.

12. The release film according to any one of claims 3 to 5, wherein the surface of the release layer has an uneven shape, and the mass content of the nitrile group-containing (meth)acrylic polymer in at least a portion of the protrusions is greater than the mass content of the nitrile group-containing (meth)acrylic polymer in at least a portion of the recesses.

13. The release film according to any one of claims 1 to 5, wherein the arithmetic mean roughness (Ra) of the outer surface of the release layer is 1.5 μm or less.

14. The weight-average molecular weight (Mw) of the aforementioned polymer is 5.0 × 10 ５ The release film according to claim 4 or claim 5.

15. At least one of the polymers is a polymer containing structural units derived from (meth)acrylonitrile monomer, The release film according to any one of claims 1 to 5, wherein the difference in the proportion of constituent units derived from (meth)acrylonitrile monomer in at least two of the polymers is 1% by mass or more.

16. The release film according to any one of claims 1 to 5, wherein the two or more polymers are (meth)acrylic polymers having constituent units derived from (meth)acryloyl monomers.

17. The release film according to any one of claims 1 to 5, wherein at least a portion of the polymer is crosslinked.

18. The release film according to any one of claims 1 to 5, wherein the content of the most abundant polymer in the release layer is 95% by mass or less of the total content of the polymer.

19. The release film according to any one of claims 1 to 5, wherein the base material layer is a polyester film.

20. The release film according to any one of claims 1 to 5, wherein the thickness of the release layer is 1 μm to 50 μm.

21. The release film according to any one of claims 1 to 5, wherein the release film is used in a transfer mold or a compression mold.

22. A method for manufacturing a semiconductor package, comprising performing a transfer molding process or a compression molding process using a release film according to any one of claims 1 to 5.

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