TW202405115A - Release film and method of producing semiconductor package - Google Patents

Abstract

A release film incudes a release layer and a substrate, in which the release layer includes two or more kind of polymer, the release layer has a concave and convex shape at the surface, and the release film meets at least one of (1) to (3): (1) in a case in which the surface of the release layer is planarly viewed from above, a ratio of the concave to the surface is 50 area % or less; and when the concave and convex shape of the release layer is transferred to the molded product, (2) the percentage (transfer rate) of an arithmetic mean roughness (Ra) of a surface of an molded article with respect to an arithmetic mean roughness (Ra) of the surface of the release layer is 100% or more, and (3) a glossiness (20°) of the surface of the molded article is 8.0 or less.

Description

Release film and method for manufacturing semiconductor packaging

The invention relates to a release film and a method for manufacturing a semiconductor package.

Semiconductor wafers are usually sealed with resin to shield and protect them from outside air, and are mounted on a substrate in the form of a molded product called a package. The molded product is produced by injecting a sealing material containing resin into a mold. A plurality of cavities are provided in the mold, and the plurality of cavities are connected via a flow path serving as a flow path for the sealing material. In addition, we have made efforts in the structure of the mold and the addition of a release agent to the sealing resin so that the molded product can be easily released from the mold.

On the other hand, in terms of requirements such as miniaturization and multi-pin packaging, Ball Grid Array (BGA) method, Quad Flat Non-leaded (QFN) method, wafer-level chip size Packaging methods such as Wafer Level-Chip Size Package (WL-CSP) are added. In the QFN method, it ensures the standoff and prevents burrs caused by the sealing material at the terminal part. In addition, in the BGA method and WL-CSP method, it improves the releasability of the package from the mold. In terms of the mold, a resin release film is arranged along the inside of the mold, and a sealing material is injected into the mold to perform molding (for example, see Patent Document 1). The method of molding using a release film is called "film-assisted molding method." [Prior art documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-158242

[Problem to be solved by the invention] When the release film is used, flow marks of the sealing material may remain on the package surface after molding, and the appearance may be degraded. In order to reduce flow marks, you can consider adding fillers to the release layer of the release film. However, this approach is not sufficient as further reduction of flow marks is required. Reducing the gloss of the package surface is effective in reducing flow marks on the package surface.

In view of this situation, an object of the present disclosure is to provide a release film that can effectively reduce the glossiness of a semiconductor package surface, and a method for manufacturing a semiconductor package using the release film. [Means to solve the problem]

Means for solving the above problems include the following embodiments. <1> A release film, including a release layer and a base material layer, The release layer contains two or more polymers, and the surface of the release layer has an uneven shape, When the surface of the release layer is viewed in a plan view, the proportion of the recessed portions in the surface is 50 area % or less. <2> A release film, including a release layer and a base material layer, The release layer contains two or more polymers, and the surface of the release layer has an uneven shape, The percentage of the arithmetic mean roughness (Ra) of the surface of the molded article relative to the arithmetic mean roughness (Ra) of the surface of the mold release layer when the uneven shape of the release layer is transferred to the molded article is: The transfer rate is over 100%. ＜3＞ A release film, including a release layer and a base material layer, The release layer contains two or more polymers, and the surface of the release layer has an uneven shape, When the uneven shape of the release layer is transferred to the molded article, the glossiness (20°) of the surface of the molded article is 8.0 or less. <4> The release film according to any one of <1> to <3>, wherein at least one of the polymers is a nitrile group-containing (meth)acrylic polymer. <5> The release film according to any one of <1> to <4>, wherein when the Raman spectroscopy measurement of the unevenness of the surface of the release layer is performed, at least a part of the convex portion and the concave portion are At least part of each shows different peak intensities. <6> The release film according to any one of <1> to <5>, wherein the component ratio of the polymer in the convex portions of the surface of the release layer is equal to the polymerization ratio in the recessed portions. The ratios of ingredients are different. <7> The release film according to <6>, wherein the mass-based content of the nitrile group-containing (meth)acrylic polymer in the convex portion is greater than the nitrile group-containing (meth)acrylic polymer in the recessed portion. The (meth)acrylic acid polymer has a large mass content. <8> The release film according to any one of <1> to <7>, wherein the difference in solubility parameter (SP) values among at least two types of the polymers is 0.3 or more. <9> The release film according to any one of <1> to <8>, wherein at least one of the polymers is a polymer containing a structural unit derived from a (meth)acrylonitrile monomer, In at least two types of the polymers, the difference in the proportions of structural units derived from (meth)acrylonitrile monomer is 1 mass % or more. <10> The release film according to any one of <1> to <9>, wherein the content ratio of the most abundant polymer in the release layer is 95 relative to the total content of the polymer. mass% or less. <11> The release film according to any one of <1> to <10>, wherein the base material layer is a polyester film. <12> The release film according to any one of <1> to <11>, wherein the thickness of the release layer is 1 μm to 50 μm. <13> The release film according to any one of <1> to <12>, which is used for transfer molding or compression molding. <14> A method of manufacturing a semiconductor package in which a transfer molding step or a compression molding step is performed using the release film according to any one of <1> to <13>. [Effects of the invention]

The present disclosure provides a release film that can effectively reduce the glossiness of a semiconductor package surface, and a manufacturing method of a semiconductor package using the release film.

Hereinafter, modes for implementing the present disclosure will be described in detail. However, this disclosure is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless otherwise stated. The same applies to numerical values and their ranges, which do not limit the disclosure.

In this disclosure, the term "step" includes not only steps that are independent of other steps, but also includes steps that are not clearly distinguishable from other steps as long as the purpose of the step is achieved. The numerical range expressed using "～" in this disclosure includes the numerical values described before and after "～" as the minimum value and the maximum value respectively. In the numerical ranges described in stages in the present disclosure, the upper limit or lower limit described in one numerical range may be replaced with the upper limit or lower limit in another numerical range described in stages. In addition, in the numerical range described in this disclosure, the upper limit value or the lower limit value of this numerical range may be replaced with the value shown in the Example. In this disclosure, a variety of corresponding substances may be included in each component. When a plurality of substances corresponding to each component are present in the composition, the content rate or content of each component means the total content rate or content of the plurality of substances present in the composition unless otherwise specified. In the present disclosure, the term "layer" includes not only the case where the layer is formed in the entire region when the region where the layer exists is observed, but also the case where the layer is formed in only a part of the region.

In this disclosure, the thickness of the release film or each layer constituting the release film can be measured by a known method. For example, it can be measured using a dial gauge or the like, or it can be measured based on a cross-sectional image of the release film. Alternatively, the material constituting the layer may be removed using a solvent or the like and calculated based on the mass before and after removal, the density of the material, the area of the layer, etc. When the thickness of the layer is not constant, the arithmetic mean of the values measured at five arbitrary points is used as the thickness of the layer. In this disclosure, "(meth)acrylic acid" means either or both acrylic acid and methacrylic acid, and "(meth)acrylate" means either acrylate or methacrylate. Or both, "(meth)acrylyl" means any one or both of acryl and methacrylyl. When the embodiment is described with reference to the drawings in the present disclosure, the structure of the embodiment is not limited to the structure shown in the drawings. In addition, the sizes of the members in each figure are conceptual, and the relative size relationship between the members is not limited to this.

＜Mold release film＞ The release film of the present disclosure includes a release layer and a base material layer, the release layer contains two or more polymers, the surface of the release layer has an uneven shape, and the release film satisfies the following (1) ~At least one of (3). (1) When the surface of the release layer is viewed in a plan view, the proportion of the recessed portion in the surface is 50 area % or less. (2) The transfer rate is the percentage of the arithmetic mean roughness (Ra) of the surface of the molded article relative to the arithmetic mean roughness (Ra) of the surface of the mold release layer when the uneven shape of the release layer is transferred to the molded article. is more than 100%. (3) When the uneven shape of the release layer is transferred to the molded article, the glossiness (20°) of the surface of the molded article is 8.0 or less. The release film of the present disclosure adopting the structure can effectively reduce the glossiness of the surface of the semiconductor package after molding. The reason for this is not yet clear, but is presumed to be as follows. In addition, the release film of this disclosure is not limited to the following speculation at all.

The release film of the present disclosure forms an uneven shape on the surface of the release layer because the release layer contains two or more polymers. For example, when the release layer has a plurality of regions with different polymer component ratios, in one region, the polymers agglomerate with each other, become denser and locally bulge, thereby forming an uneven shape on the surface of the release layer. Furthermore, the surface of the release layer may have an uneven shape, and the component ratio of the polymer in the convex parts may be different from the component ratio of the polymer in the recessed parts. Thereby, regarding the release film of this disclosure, even if a filler is not added to a release layer, unevenness|corrugation can be produced in the surface of a release film.

In this disclosure, "polymer" refers to a high molecular weight component that does not contain organic fillers. Here, the organic filler is insoluble or poorly soluble in an organic solvent (for example, toluene, methyl ethyl ketone, and ethyl acetate) that can be used for adjusting the composition for forming a release layer. Here, the term "insoluble or poorly soluble in an organic solvent" means that the resin particles are dispersed in an organic solvent such as toluene in a gel fraction test based on Japanese Industrial Standard (JIS) K6769 (2013) The gel fraction after maintaining at 50°C for 24 hours was 97% by mass or more. In this disclosure, "different types of polymers" means that the types of constituent monomers are different, or the types of constituent monomers are the same, but the content of structural units derived from at least one monomer differs by 1% by mass. above.

As one specific method of forming a plurality of regions with different polymer component ratios, it is preferable to use two or more polymers whose SP value difference is 0.3 or more. Polymers with a SP value difference of 0.3 or more have low compatibility, and therefore polymers of the same type tend to agglomerate while being separated from each other, thereby tending to easily form uneven shapes on the surface of the release layer. In particular, 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 easily form convex portions.

In addition, it is preferable that when Raman spectrometry is performed on the convex portion and the concave portion, different peak intensities are shown in at least a part of the convex portion and at least a part of the concave portion. The term "at least a part of the convex part and at least a part of the concave part show different peak intensities when Raman spectroscopy is measured" means that at least part of the convex part and at least a part of the concave part show different peak intensities when Raman spectroscopy is measured. Different wave peak intensities are enough. When there are a plurality of convex parts, the peak intensities of the respective convex parts may be the same or different. When there are a plurality of recessed portions, the peak intensities of the respective recessed portions may be the same or different. In this disclosure, "different peak intensities are displayed when Raman spectroscopy is measured" means that the peaks appearing at a certain position in the Raman spectrum obtained by Raman spectroscopy have different intensities. The difference between whether there is a wave peak at a certain position is also included in the situation where the intensity of the wave peak is different.

In conventional release films, fillers are added to the release layer to create unevenness on the surface of the release layer, thereby reducing flow marks of the sealing material on the surface of the semiconductor package. In such a conventional release film, since the filler protrudes from the surface of the release layer, the bottom of the recess corresponds to the surface of the release layer before the filler is added, and therefore the bottom of the recess is flat. Since the uneven shape on the surface of the release layer is transferred to the sealing molded product on the surface of the semiconductor package, the apex of the convex portion formed on the surface of the semiconductor package becomes flat. Therefore, the glossiness is not sufficiently reduced on the surface of the semiconductor package in which the protrusions having flat apexes are formed.

On the other hand, in the release film of the present disclosure, the release layer forms an uneven shape on the surface of the release layer by using two or more polymers, and the proportion of the recessed portions in the surface of the release layer is 50 area %. below, so the front end of the bottom of the recess becomes pointed. The reason for this is not yet clear, but it is presumed that the depressions are formed by polymers of the same kind coagulating together, shrinking, and stretching. On the surface of the semiconductor package to which the shape of the release film surface of the present disclosure is transferred, the apex of the convex portion becomes sharp, and the glossiness of the semiconductor package surface is effectively reduced. Furthermore, the release film of the present disclosure is not limited to one in which the bottom of the recess is cut at an acute angle. It may be an obtuse angle or a curved surface, and the bottom of the recess may also be partially flat. The shape of the recessed portion may be formed by a combination of these. In addition, the bottoms of some of the recessed portions among the plurality of recessed portions may be flat.

Therefore, when the release layer contains two or more polymers, when the uneven shape of the release layer of the release film is transferred to the molded article, (2) the arithmetic mean roughness (Ra) of the surface of the molded article is relatively The percentage of arithmetic mean roughness (Ra) on the surface of the release layer, that is, the transfer rate is 100% or more, and (3) the glossiness (20°) of the surface of the molded product can be made 8.0 or less.

Furthermore, in the release film of this disclosure, an uneven shape can be formed on the surface even without adding a filler, so the occurrence of problems such as the fall-off of the filler can be suppressed. In addition, in the conventional release film, the release layer was easily broken starting from the filler, but in the release film of the present disclosure, breakage of the release layer can also be suppressed. Furthermore, the release layer also has excellent extensibility. The release layer has excellent extensibility, and the release film has excellent followability to the mold. In addition, when the breakage of the mold release layer is suppressed, the sealing material is suppressed from coming into contact with the mold at the broken portion, and the molded product is excellent in the removable property from the mold.

In the release film of this disclosure, an uneven shape can be formed on the surface even without adding a filler, and therefore a convex portion in which a clear interface cannot be confirmed can be formed. The term "convex portions in which a clear interface cannot be confirmed" means that when observed with a laser microscope, a particle interface cannot be confirmed as when a filler is added.

As an example of the release film of this disclosure, the cross-sectional structure of the release film is schematically shown in FIG. 1 . As shown in FIG. 1 , the release film 30 includes a base material layer 10 and a release layer 20 . The release film 30 may also have other layers. Examples of other layers include a second release layer, an anchor improving layer, an antistatic layer, a colored layer, and the like.

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

In this disclosure, when there are two types of polymers contained in the release layer, the difference in SP value refers to the difference in SP value between the polymers. When the release layer contains three or more types of polymers, the difference in SP value refers to the difference between the polymer with the highest SP value and the polymer with the lowest SP value among the polymers contained in the release layer. The difference in SP value.

The SP value is a solubility parameter derived from the local structural unit of the chemical structural formula, and is a value calculated by the Fedors method.

The type of polymer is not particularly limited, but it is preferably selected considering the adhesion, releasability, heat resistance, etc. of the release layer. Specific examples of the polymer include (meth)acrylic polymers having structural units derived from (meth)acrylyl monomers, silicones, urethane polymers, and the like. At least one type of polymer is preferably a (meth)acrylic acid polymer, and more preferably two or more (meth)acrylic acid polymers are used.

The proportion of the (meth)acrylic acid polymer in the total polymer is preferably 20 mass% or more, more preferably 40 mass% or more, further preferably 60 mass% or more, and may be 80 mass% or more, 85 mass% or more. % or more, 90 mass % or more, 95 mass % or more. The upper limit is not particularly limited, and the ratio may be 100% by mass, 95% by mass or less, 90% by mass or less, or 85% by mass or less.

The (meth)acrylic acid polymer may be a homopolymer or a copolymer, and a homopolymer and a copolymer may be used together. At least one of the (meth)acrylic acid polymers is preferably a copolymer. The copolymer may contain structural units derived from monomer A which does not have a functional group, or may contain structural units derived from monomer B which has a functional group.

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

When the copolymer contains structural units derived from monomer A, the total content of the structural units derived from monomer A in the copolymer is preferably more than 50 mass %, more preferably 55 mass % or more, and still more preferably It is more than 60 mass%. In addition, the total content rate is preferably 99 mass% or less, more preferably 98 mass% or less, still more preferably 97 mass% or less.

At least one polymer is preferably a copolymer containing structural units derived from monomer B having a functional group. Examples of the functional group include a carboxylic acid group, a hydroxyl group, a amide group, a nitrile group, and the like. The functional group may be a cross-linking functional group or a non-cross-linking functional group. Examples of crosslinkable functional groups include carboxylic acid groups, hydroxyl groups, amide groups, and the like, and examples of non-crosslinkable functional groups include nitrile groups and the like. The copolymer may contain one structural unit derived from monomer B alone or in combination of two or more. More preferably, at least one polymer is a nitrile group-containing (meth)acrylic acid polymer.

At least part of the crosslinked polymer having a crosslinkable functional group may be crosslinked and included in the release film. In this disclosure, when two or more polymers are cross-linked, the release film is also included in the form containing two or more polymers.

When a polymer is cross-linked, the polymer before cross-linking can be analyzed or estimated by decomposing the bond passing through the cross-linking point. For example, when a polymer has a hydroxyl group and an isocyanate compound is used as a cross-linking agent, it is estimated that a urethane bond is formed and cross-linked, and the urethane bond can be selectively decomposed by pyridine.

The cross-linked polymer is preferably a cross-linked (meth)acrylic acid polymer, and more preferably a cross-linked (meth)acrylic acid copolymer.

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

In at least one polymer, the total content of structural units derived from monomer B1 is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and still more preferably 1.0 mass% or more. In addition, the total content rate is preferably 30 mass% or less, more preferably 25 mass% or less, and still more preferably 20 mass% or less.

In at least one kind of polymer, the total content of structural units derived from monomer B2 is preferably 1 mass % or more, more preferably 3 mass % or more, and still more preferably 5 mass % or more. In addition, the content rate is preferably 55 mass% or less, more preferably 50 mass% or less, and still more preferably 45 mass% or less.

At least one of the polymers is preferably a copolymer containing a structural unit derived from a monomer having a nitrile group, more preferably a copolymer containing a structural unit derived from a (meth)acrylonitrile monomer. The polymer used together may be a homopolymer not containing a structural unit derived from a monomer having a nitrile group, or a copolymer not containing a structural unit derived from a monomer having a nitrile group.

In the copolymer containing a structural unit derived from a monomer having a nitrile group, the content rate of the structural unit derived from the monomer having a nitrile group is preferably 1 mass % or more, more preferably 3 mass % or more, and still more preferably It is 5 mass% or more. In addition, the content rate is preferably 55 mass% or less, more preferably 50 mass% or less, and still more preferably 45 mass% or less.

The total content of structural units derived from monomer A in a copolymer containing structural units derived from a monomer having a nitrile group is preferably 35 mass % or more, more preferably 40 mass % or more, and still more preferably 50 Quality% or more. In addition, the total content rate is preferably 94 mass% or less, more preferably 92 mass% or less, and still more preferably 90 mass% or less.

The total content of structural units derived from monomer B1 in a copolymer containing structural units derived from a monomer having a nitrile group is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and still more preferably 1.0 Quality% or more. In addition, the total content rate is preferably 30 mass% or less, more preferably 25 mass% or less, and still more preferably 20 mass% or less.

The total content of structural units derived from monomer A in a copolymer that does not contain structural units derived from a monomer having a nitrile group is preferably 70 mass % or more, more preferably 75 mass % or more, and still more preferably More than 80% by mass. In addition, the total content rate is preferably 99 mass% or less, more preferably 98 mass% or less, still more preferably 97 mass% or less.

The total content of structural units derived from monomer B1 in a copolymer that does not contain structural units derived from a monomer having a nitrile group is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and still more preferably 1.0% by mass or more. In addition, the total content rate is preferably 30 mass% or less, more preferably 25 mass% or less, and still more preferably 20 mass% or less.

In at least two types of polymers, the difference in the proportion of structural units derived from (meth)acrylonitrile monomer is preferably 1 mass % or more, more preferably 3 mass % or more, and still more preferably 5 mass % above. The upper limit of the difference in the ratio of structural units derived from (meth)acrylonitrile monomer is not particularly limited, but is preferably 55 mass% or less, more preferably 50 mass% or less, and still more preferably 45 mass% the following.

Preferred combinations of two (meth)acrylic polymers include the following (I) and (II), with (I) being preferred. (I) Combination of nitrile group-containing (meth)acrylic acid polymer and nitrile group-free (meth)acrylic acid polymer (II) Both are nitrile group-containing (meth)acrylic polymers, and the content rates of structural units derived from (meth)acrylonitrile monomers are different from each other.

The number average molecular weight (Mn) of the polymer may be, for example, 1.0×10 ³ or more, or 1×10 ⁴ or more. In addition, for example, it may be 1.0×10 ⁶ or less, or it 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, or 1.0×10 ⁴ or more. In addition, for example, it may be 5.0×10 ⁶ or less, or it may be 1.0×10 ⁶ or less. The Mn and Mw of the polymer are measured by a common method using gel permeation chromatography (GPC).

The content rate of the most abundant polymer in the release layer is preferably 95 mass % or less, more preferably 90 mass % or less, and still more preferably 85 mass % or less relative to the total content of the polymer. If the content of the polymer with the largest content is 95% by mass or less, unevenness tends to be easily formed on the surface of the release film.

When the polymer is a cross-linked polymer, it is preferred to use a cross-linking agent. Examples of the cross-linking agent include known cross-linking agents such as isocyanate compounds, melamine compounds, and epoxy compounds. In addition, from the viewpoint of forming a slowly expanding network structure, the crosslinking agent is more preferably a multifunctional crosslinking agent such as a trifunctional or tetrafunctional crosslinking agent.

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

Examples of the difunctional isocyanate compound include aliphatic diisocyanate compounds, alicyclic diisocyanate compounds, aromatic diisocyanate compounds, carbodiimide modified products of these diisocyanate compounds, and compounds having these diisocyanate compounds in their molecules. Polymer compounds, etc.

Examples of aliphatic diisocyanate compounds include 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), and trimethylhexamethylene diisocyanate. (trimethylhexamethylene diisocyanate, TMHDI), lysine diisocyanate, norbornane dimethyleneisocyanate (NBDI), etc.

Examples of alicyclic diisocyanate compounds include trans-cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), and cyclohexane dimethylene diisocyanate. H6-XDI) (Hydrogenated xylylene diisocyanate, 4,4'-diisocyanate (diphenylmethane-4,4'-diisocyanate, MDI), etc.

Examples of aromatic diisocyanate compounds include dimer diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), and 2,6-toluene 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), tetramethyl xylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5 -Naphthalene diisocyanate (1,5-naphthalene diisocyanate, NDI), etc.

Examples of the polyfunctional isocyanate compound include a trimer of a difunctional isocyanate compound, a polymer compound having a trimer of a difunctional isocyanate compound in the molecule, and the like. Examples of the trimer of the difunctional isocyanate compound include an isocyanurate body of the difunctional isocyanate compound, an adduct of the difunctional isocyanate compound, and a biuret body of the difunctional isocyanate compound.

The content of the 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 relative to 100 parts by mass of the solid content of the polymer contained in the release layer.

The release layer may also contain an anchoring enhancer, a crosslinking accelerator, a colorant, an antistatic agent, etc. as needed. For example, when the release layer contains an antistatic agent, discharge is less likely to occur during peeling, and electrostatic damage to electronic components is suppressed.

When Raman spectroscopy is performed on the surface irregularities of the release layer, it is preferable that at least a part of the convex portions and at least a part of the concave portions each show different peak intensities. As an example, at least part of the convex part and at least part of the recessed part may have different polymer component ratios. As a further specific example, it is preferable that the content of the nitrile group-containing (meth)acrylic polymer is different in at least a part of the convex portion and at least a part of the concave portion. In addition, the peak showing different peak intensities is preferably a peak derived from a nitrile group.

The Raman spectrum measurement in each uneven portion uses a Raman spectroscopic device. As a Raman spectroscopy device, for example, "DXR2xi" manufactured by Thermo Fischer Scientific is used, and measurement is performed under the following conditions. ・Wavelength: 532 nm ・Power: 10 mW ・Exposure time: 0.05 seconds ・Number of scans: 1000 times ・Aperture: 25 μm pinhole ・Objective lens: 100x

The component ratio in each uneven portion is measured by obtaining a spectrum of the portion irradiated with laser one by one using Raman spectroscopy. For example, for a specific component (such as nitrile group) constituting the release layer, the peak of the Raman spectrum is identified in advance, and based on its signal intensity, the relative content of the specific component at one location and another location is confirmed.

In the release layer, at least one region preferably contains a nitrile group-containing (meth)acrylic polymer, and the other region may contain a nitrile group-containing (meth)acrylic polymer, or it may not contain a nitrile group. of (meth)acrylic acid polymers. From the viewpoint of easily creating unevenness on the surface of the release layer, it is preferable that the nitrile group-containing (meth)acrylic polymer is not included in the other region. Furthermore, whether a nitrile group-containing (meth)acrylic polymer is not included in a region can be determined by analyzing the components of the region using the micro-Raman spectroscopy method described below. No spectrum corresponding to the nitrile group was detected. crest to confirm.

Regarding each region, when the surface of the release layer is planarly observed, a phase separation state occurs within the layer, and a continuous phase and a discontinuous phase can be formed. The area ratio of the continuous phase and the discontinuous phase can be adjusted by the compounding ratio of the polymer contained in the release layer. The polymer with a small content ratio in the release layer is included in the discontinuous phase, and the polymer with a large content ratio is included in the continuous phase.

Moreover, it is preferable that the surface of the release layer has an uneven shape, and that the component ratio of the polymer in at least a part of the convex parts is different from the component ratio of the polymer in at least a part of the recessed parts. As an example, it is preferable that the content of the nitrile group-containing (meth)acrylic polymer on a mass basis is different in at least a part of the convex part and at least a part of the recessed part, and that the content of the nitrile group-containing (meth)acrylic polymer is different in the convex part than in at least a part of the recessed part. The content on a mass basis of at least one part of the nitrile group-containing (meth)acrylic polymer is greater.

FIG. 2 is a photograph and an analysis chart of the surface of the release layer using a laser microscope. "VK-X3000" manufactured by Keyence Co., Ltd. was used as a laser microscope, and observation was performed with a 50x objective lens. In Figure 2, the laser microscope is used, but other laser microscopes can also be used on the surface of the release layer.

In Figure 2, sample G1 is a previous release layer containing a filler, and samples G2 and G3 use a combination of a (meth)acrylic polymer (polymer A) containing a nitrile group and a (methyl) polymer without a nitrile group. The release layer of the present disclosure is an acrylic polymer (Polymer B). Regarding sample G2, the content of polymer A in the total polymer was 15% by mass, and the content of polymer B was 85% by mass. Regarding sample G3, the content of polymer A in the total polymer was 85% by mass, and the content of polymer B was 15% by mass.

The first and second sections of Figure 2 are planar photographs of the surface of the release layer when viewed in plan. The third section of Figure 2 shows the concave and convex shapes of the surface on the straight line indicated by the arrow in the second section of the photograph. Analytical profile curve. As shown in FIG. 2 , in samples G2 and G3, the release layer is formed in a plurality of regions.

Regarding sample G2, the content rate of the nitrile group-containing (meth)acrylic polymer in the entire polymer is less than half. In this case, the area occupied by the convex portion in the entire surface is less than half. On the other hand, in sample G3, the content rate of the nitrile group-containing (meth)acrylic polymer in the entire polymer exceeds half. In this case, the area occupied by the convex portion exceeds half of the entire surface. From this, it can be seen that the content rate of the nitrile group-containing (meth)acrylic polymer is greater in the convex portions than in the concave portions. Furthermore, as shown in FIG. 2 , in the previous sample G1, the filler was aggregated, so it was found that the uniformity of the shape, size, etc. of the convex portions was low.

In sample G2, the concave portion occupies most of the entire surface. On the other hand, in sample G3, the recessed portion occupies 50 area % or less of the entire surface. Therefore, sample G3 is the release film of the present disclosure.

As shown in the cross-sectional curve of FIG. 2 , in the sample G3 which is the release film of the present disclosure, the bottom tip of the recessed portion is sharper than the previous sample G1 to which a filler was added. Therefore, it is found that the glossiness of the package surface formed using the release film of the present disclosure is effectively reduced.

In the release film of this disclosure, the proportion of the recessed portion in the surface when the surface of the release layer is viewed in a plan view is preferably 50 area % or less, more preferably 45 area % or less, and still more preferably 40 area % or less. The proportion of the recessed portion in the surface of the release layer is measured by the following method.

The surface of the release film was photographed using an optical microscope at 400 times. The range of the concave portion and the convex portion is divided based on the difference in brightness contrast of the captured image. Compare the areas of the divided concave portions and the convex portions. The concave portion and the convex portion can be determined based on a three-dimensional image composed of a plurality of images taken at the same position with respect to the plane direction and moved in the height direction. This measurement can use a digital microscope (for example, VHX-7000 manufactured by Keyence Co., Ltd.) and other devices, and the proportion of the recessed portion can be calculated using image processing. When the image processing device cannot be used, the concave portion and the convex portion can be individually determined in the captured image and distinguished to obtain the area. When finding the area, you can also cut out the divided image and compare it based on the weight.

When the surface of the release layer is viewed in a plan view, the maximum diameter of the recessed portion is preferably 30 μm or less. As long as the release layer exhibits release properties, the lower limit of the maximum diameter of the recessed portion is not particularly limited.

The maximum diameter of the recessed portion is a value obtained by measuring the diameter of the recessed portion having the largest diameter when observing with an optical microscope at one field of view at 400 times.

When the surface of the release layer is planarly observed with an optical microscope, the circularity of the recessed portion is preferably 0.7 or more, more preferably 0.8 or more. "Circularity" is a value calculated using the following formula, and is an index indicating the complexity of the particle shape. The closer the circularity is to 1, the closer the particle shape is to a perfect circle. Circularity=4π×(Area)÷(Perimeter) ²

The circularity of the concave portion is the arithmetic mean value of the circularity measured for ten convex portions when observed with an optical microscope. The circularity of the convex portion can be calculated using known image analysis means if necessary.

As shown in sample G1 of FIG. 2 , in the case of the previous release film to which fillers are added, the fillers tend to agglomerate and the circularity of the recessed portions tends to decrease. In particular, when a large amount of filler is added in order to reduce the proportion of recessed portions in the surface of the release layer, the fillers are more likely to agglomerate, and the circularity of the recessed portions is likely to further decrease.

Furthermore, based on the relationship between the blending ratio of the polymer in Sample G2 and Sample G3 and the proportion occupied by the convex parts, it can be inferred that the content rate of the nitrile group-containing (meth)acrylic polymer changes in the convex parts compared with the concave parts. many. In addition, as shown in FIG. 2 , it was found that the filler was aggregated in the previous sample G1, so the uniformity of the shape, size, etc. of the convex portion was low.

Figure 3 is a spectrum result obtained by analyzing the components of the discontinuous phase (island phase, convex parts) and the continuous phase (marine phase, concave parts) in sample G2 in Figure 2 using micro-Raman spectroscopy. Here, the discontinuous phase refers to a region that occupies a small area on the observation surface, and the continuous phase refers to a region that occupies a large area on the observation surface.

As shown in FIG. 3 , the peak derived from the nitrile group was detected in the discontinuous phase (convex portion), whereas the peak derived from the nitrile group was not detected in the continuous phase (concave portion). From this result, it can be seen that the component ratio of the polymer is different in the discontinuous phase (convex portions) and the continuous phase (concave portions). In addition, it is found that the content of the nitrile group-containing (meth)acrylic polymer is greater in the convex parts than in the concave parts.

Figure 4 is a spectrum result obtained by analyzing the components of the convex parts (marine phase, continuous phase) and concave parts (island phase, discontinuous phase) in sample G3 in Figure 2 using micro-Raman spectroscopy. The peak derived from the nitrile group was detected in the convex portion, whereas the peak derived from the nitrile group was not detected in the concave portion. From this result, it can be seen that the component ratio of the polymer is different between the convex portion and the concave portion. In addition, it is found that the content of the nitrile group-containing (meth)acrylic polymer is greater in the convex parts than in the concave parts. In FIG. 4 , a continuous phase is formed including the nitrile group-containing (meth)acrylic polymer as a main component among all the polymers, but this continuous phase forms convex portions. In FIG. 3 , the continuous phase forms a concave portion, whereas in FIG. 4 , the continuous phase is reversed. However, in both cases of FIGS. 3 and 4 , the nitrile group-containing (meth)acrylic polymer is contained in the convex portions more than in the concave portions.

The thickness of the release layer is not particularly limited, but it is preferably 1 μm or more, more preferably 3 μm or more, and still more preferably 5 μm or more. If the thickness of the release layer is 1 μm or more, sufficient adhesion to electronic parts can be obtained and the intrusion of the sealing material can be 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, heat shrinkage stress is less likely to occur when the release layer is thermally cured, making it easier to maintain the flatness of the release film. In addition, when the release film has a conductive layer, the distance between the surface of the release layer and the conductive layer is not too far, the surface resistivity is maintained low, and electrostatic damage of electronic components can be effectively suppressed. Taking into account the ease of formation of the release layer (coatability, etc.), ensuring the adhesion, etc., the thickness of the release layer is preferably 1 μm to 50 μm, more preferably 3 μm to 25 μm.

From the viewpoint of maximizing the effect of the embodiment of the present disclosure, the release layer preferably does not contain a filler, but it may contain a filler. When a filler is used, it may be at least one of an organic filler and an inorganic filler. The content rate of the filler in the release layer can be, for example, 1 volume % or less, 0.5 volume % or less, or 0.1 volume % or less. The content rate (volume %) of the filler in the release layer can be calculated based on the density measured by Archimedes' method, the resin component, and the specific gravity of the filler.

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

The elongation at break (%) of the release layer of the release film is measured as follows. First, a release film was used to prepare a test piece having a shape as shown in Fig. 5 . The test piece was grasped at both ends with a testing machine and a tensile test was performed. The measurement was performed at 170°C, and the stretching speed was set to 200 mm/min. Based on the distance A between the marking points of the sample before the test (the length of the 10 mm wide part of the test piece shown in Figure 5: 40 mm) and the distance B between the marking points when the release layer breaks, the release layer is calculated by the following formula Elongation at break of the mold layer.

[Number 1]

For the measurement of the elongation at break of the release layer of the release film, for example, "Tensilon tensile testing machine RTA-100 model" manufactured by Orientec Co., Ltd., or A&D Co., Ltd. "Tensilon Universal Testing Machine RTG-1210" or a similar testing machine with a grabber.

(Surface roughness of release layer) The arithmetic mean roughness (Ra) of the outer surface of the release layer (the surface opposite to the surface facing the base material layer) is preferably 0.15 μm or more, more preferably 0.20 μm or more, and still more preferably 0.25 μm or more. The upper limit of the arithmetic mean roughness (Ra) is not particularly limited, but may be 4.00 μm or less, 3.00 μm or less, or 2.00 μm or less, for example.

The arithmetic mean roughness (Ra) of the outer surface of the release layer can be determined by JIS B0601 (2001) or International Standards Organization (ISO) 4287 (1997) using a surface roughness measuring device (for example, Kosaka Laboratory (stock), Model SE-3500) was obtained by analyzing the results measured under the conditions of stylus tip diameter 2 μm, feed speed 0.5 mm/s, and scanning distance 8 mm.

In the release film, when the uneven shape of the release layer of the release film is transferred to the molded product, the arithmetic mean roughness (Ra) of the surface of the molded product is relative to the arithmetic mean roughness (Ra) of the surface of the release layer. The percentage (transfer rate) is preferably 100% or more, more preferably 103% or more, and further preferably 110% or more. The transfer rate of the release film is preferably 300% or less, more preferably 250% or less, and still more preferably 200% or less.

The 10-point average roughness (Rz) of the outer surface of the release layer is preferably 1.00 μm or more, more preferably 1.50 μm or more, and still more preferably 2.00 μm or more. The upper limit of the 10-point average roughness (Rz) is not particularly limited. For example, it may be 30.00 μm or less, 20.00 μm or less, or 10.00 μm or less.

The 10-point average roughness (Rz) of the outer surface of the release layer can be determined by JIS B0601 (1994) using a surface roughness measuring device (e.g., Kosaka Laboratory Co., Ltd., model SE-3500) on the tip diameter of the stylus It is obtained by analyzing the results measured under the conditions of 2 μm, feed speed 0.5 mm/s, and scanning distance 8 mm.

The average interval (Sm) of the concavities and convexities on the outer surface of the release layer is preferably 0.30 mm or less, more preferably 0.25 mm or less, and still more preferably 0.20 mm or less. The lower limit of the average distance between concavities and convexities (Sm) is not particularly limited, but may be 0.01 mm or more, 0.02 mm or more, or 0.03 mm or more, for example.

The average interval (Sm) of the concavities and convexities on the outer surface of the release layer can be determined by JIS B0601 (1994) using a surface roughness measuring device (for example, Kosaka Laboratory Co., Ltd., model SE-3500) at the stylus tip diameter 2 μm, a feed speed of 0.5 mm/s, and a scanning distance of 8 mm were measured and analyzed.

The average length (RSm) of the roughness curve elements of the outer surface of the release layer is preferably 0.50 mm or less, more preferably 0.30 mm or less, and still more preferably 0.10 mm or less. The lower limit of RSm is not particularly limited. For example, it may be 0.01 mm or more, 0.03 mm or more, or 0.05 mm or more.

The average length (RSm) of the roughness curve elements of the outer surface of the release layer can be determined by JIS B0601 (2001) using a surface roughness measuring device (for example, Kosaka Laboratory Co., Ltd., model SE-3500) on the stylus It is obtained by analyzing the results measured under the conditions of tip diameter 2 μm, feed speed 0.5 mm/s, and scanning distance 8 mm.

The maximum height (Ry) of the outer surface of the release layer is preferably 1.0 μm or more, more preferably 1.5 μm or more, further preferably 2.0 μm or more. The upper limit of the maximum height (Ry) is not particularly limited, but may be 30.0 μm or less, 20.0 μm or less, or 10.0 μm or less, for example.

The maximum height (Ry) of the outer surface of the release layer can be determined by JIS B0601 (2001) using a surface roughness measuring device (for example, Kosaka Laboratory Co., Ltd., model SE-3500) at the stylus tip diameter 2 μm, It is obtained by analyzing the results measured under the conditions of feed speed 0.5 mm/s and scanning distance 8 mm.

In the release film, when the uneven shape of the release layer of the release film is transferred to the molded article, the difference between the 10-point average roughness (Rz) and the maximum height (Ry) of the surface of the molded article is preferably 2.00 μm or less. , more preferably 1.50 μm or less, further preferably 1.00 μm or less. The difference is preferably 0.30 μm or more, more preferably 0.40 μm or more, still more preferably 0.50 μm or more.

The arithmetic mean roughness (Ra), the 10-point average roughness (Rz), the average interval between concavities and convexities (Sm), the average length of the roughness curve elements (RSm), and the maximum height (Ry) of the outer surface of the release layer can be determined It is adjusted by the blending ratio of the polymer contained in the release layer, the thickness of the release layer, the amount of crosslinking when using a crosslinking agent, the amount of catalyst when using a catalyst, etc.

The surface gloss (20°) of the release layer is preferably 28.0 or less, more preferably 25.0 or less, and even more preferably 20.0 or less. The lower limit of the glossiness (20°) of the surface of the release layer is not particularly limited, but may be, for example, 1.0 or more, 3.0 or more, or 5.0 or more.

The surface gloss (60°) of the release layer is preferably 44.0 or less, more preferably 40.0 or less, still more preferably 35.0 or less. The lower limit of the glossiness (60°) of the surface of the release layer is not particularly limited, but may be, for example, 3.0 or more, 5.0 or more, or 10.0 or more.

The surface gloss (85°) of the release layer is preferably 60.0 or less, more preferably 45.0 or less, and still more preferably 35.0 or less. The lower limit of the glossiness (85°) of the surface of the release layer is not particularly limited, but may be, for example, 1.0 or more, 3.0 or more, or 5.0 or more.

Glossiness is measured using a gloss measuring machine based on the specular gloss measurement method of JIS Z 8741 (1997). Glossiness (20°) is measured at an incident angle of 20 degrees, gloss (60°) is measured at an incident angle of 60 degrees, and gloss (85°) is measured at an incident angle of 85 degrees.

In the release film, when the uneven shape of the release layer of the release film is transferred to the molded article, the glossiness (20°) of the surface of the molded article is preferably 8.0 or less, more preferably 5.0 or less, and still more preferably 3.0. the following. The lower limit of the glossiness (20°) of the surface of the molded article is not particularly limited, but may be, for example, 0.3 or more, 0.5 or more, or 1.0 or more.

In the release film, when the uneven shape of the release layer of the release film is transferred to the molded article, the glossiness (60°) of the surface of the molded article is preferably 30.0 or less, more preferably 20.0 or less, and still more preferably 15.0. the following. The lower limit of the glossiness (60°) of the surface of the molded article is not particularly limited, but may be 1.0 or more, 3.0 or more, or 5.0 or more, for example.

In the release film, when the uneven shape of the release layer of the release film is transferred to the molded article, the glossiness (85°) of the surface of the molded article is preferably 65.0 or less, more preferably 50.0 or less, and still more preferably 30.0. the following. The lower limit of the glossiness (85°) of the surface of the molded article is not particularly limited, but may be 1.0 or more, 5.0 or more, or 10.0 or more, for example.

[Substrate layer] The base material layer is not particularly limited, and can be appropriately selected from base material layers used in this technical field. From the viewpoint of improving the ability to follow the shape of the mold, it is preferable to use a resin-containing base material layer that is excellent in extensibility. Considering the heating temperature used for molding the sealing material (approximately 100° C. to 200° C.), it is desirable that the base material layer has heat resistance higher than the heating temperature. In addition, from the viewpoint of suppressing the occurrence of wrinkles, cracks, etc. when the release film is mounted on the mold and when the sealing material flows, it is preferable to select the base material taking into account the elastic modulus, elongation, etc. during heating. layer material.

From the viewpoint of heat resistance and elastic modulus during heating, the material of the base layer is preferably polyester resin. Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, and copolymers and modified resins thereof.

The base material layer is preferably in a sheet shape, more preferably a polyester resin molded into a sheet shape, further preferably a polyester film, and from the viewpoint of mold followability, biaxially stretched polyester is more preferably membrane.

The thickness of the base material layer is not particularly limited, but is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm. If the thickness is 5 μm or more, the workability will be excellent and wrinkles will tend to be less likely to occur. When the thickness is 100 μm or less, the mold followability during molding is excellent, so the occurrence of wrinkles and the like in the molded semiconductor package tends to be suppressed.

[Other structures] Depending on the material of the base material layer, it is preferably designed so that the release sheet can be easily peeled off from the mold. For example, the opposite surface of the base layer that is in contact with the release layer, that is, the surface of the base layer on the mold side may be subjected to surface processing such as pear peel processing, 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 peelability from the mold, heat resistance, etc., and the same material as the release layer (hereinafter also referred to as "specific release layer") can be used. Same material. The thickness of the second release layer is not particularly limited, but is preferably 0.1 μm to 100 μm.

Furthermore, if necessary, an anchoring improvement layer, an antistatic layer, a colored layer, etc. may be provided between a specific release layer and the base material layer, between the base material layer and the second release layer, or the like.

＜Manufacturing method of release film＞ The release film of this disclosure can be produced by a known method. For example, the release film of this disclosure can be manufactured by applying a composition for forming a release layer to a base material layer and drying it. The composition for forming a release layer includes at least two polymers, and may further include other resin components and other components added as needed.

[Preparation of composition for forming release layer] The preparation method of the composition for forming a release layer is not particularly limited, and a known composition preparation method can be used. The solvent used in preparing the composition for forming a release layer is not particularly limited, but an organic solvent capable of dissolving the polymer is preferred. Examples of the organic solvent include toluene, methyl ethyl ketone, ethyl acetate, and the like.

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

＜Use of release film＞ The release film of this disclosure is used, for example, when sealing a semiconductor wafer with a sealing material. The release film of the present disclosure is preferably used in transfer molding or compression molding.

By using the release film of the present disclosure, the semiconductor package (molded article) can be easily removed from the mold while suppressing damage to the semiconductor package. In addition, by using the release film of the present disclosure, the glossiness of the sealing material is effectively reduced on the surface of the semiconductor package (molded product), flow marks are suppressed, and the uniformity of the appearance is excellent.

＜Manufacturing method of semiconductor package＞ In the manufacturing method of a semiconductor package of the present disclosure, the transfer molding step or the compression molding step is performed using the release film of the present invention.

In a method of manufacturing a semiconductor package, first, the release film of the present disclosure is placed on a mold of a molding device so that the release film follows the shape of the mold. Examples of a method for making the release film follow the shape of the mold include vacuum adsorption.

Then, the semiconductor wafer is sealed with a sealing material in the mold followed by the release film. A semiconductor package can be manufactured by sealing the semiconductor wafer with a sealing material while the semiconductor wafer and the release film are arranged in the mold. After the semiconductor package is manufactured, the mold is opened and the formed semiconductor package is taken out.

In the manufacturing method of the semiconductor package of the present disclosure, since the release film of the present disclosure is used, the glossiness of the sealing material on the surface of the semiconductor package is effectively reduced, flow marks are suppressed, and a semiconductor with excellent appearance uniformity can be obtained. Encapsulation.

Examples of the semiconductor wafer used in the method include semiconductor elements, capacitors, terminals, and the like. The type of sealing material used in the method is not particularly limited, and examples thereof include resin compositions containing epoxy resin, acrylic resin, and the like.

The uneven shape of the surface of the release film is transferred to the surface of the semiconductor package, and the transfer rate is preferably 100% or more, more preferably 103% or more, and still more preferably 110% or more. The transfer rate of the release film is preferably 300% or less, more preferably 250% or less, and still more preferably 200% or less. The transfer rate described here has the same meaning as the transfer rate described for the release film.

The arithmetic mean roughness (Ra) of the surface of the semiconductor package is preferably 0.15 μm or more, more preferably 0.20 μm or more, and still more preferably 0.25 μm or more. The upper limit of the arithmetic mean roughness (Ra) of the surface of the semiconductor package is not particularly limited. For example, it may be 4.00 μm or less, 3.00 μm or less, or 2.00 μm or less. The arithmetic mean roughness (Ra) of the surface of the semiconductor package is measured by the same method as the arithmetic mean roughness (Ra) of the surface of the release layer.

The 10-point average roughness (Rz) of the surface of the semiconductor package is preferably 1.00 μm or more, more preferably 2.00 μm or more, and further preferably 3.80 μm or more. The upper limit of the 10-point average roughness (Rz) of the surface of the semiconductor package is not particularly limited. For example, it may be 30.00 μm or less, 20.00 μm or less, or 10.00 μm or less. The 10-point average roughness (Rz) of the surface of the semiconductor package is measured using the same method as the 10-point average roughness (Rz) of the surface of the release layer.

The average interval (Sm) of the concavities and convexities on the surface of the semiconductor package is preferably 0.30 mm or less, more preferably 0.25 mm or less, still more preferably 0.20 mm or less. The lower limit of the average spacing (Sm) of the concavities and convexities on the surface of the semiconductor package is not particularly limited. For example, it may be 0.01 mm or more, 0.02 mm or more, or 0.03 mm or more. The average interval (Sm) of the unevenness on the surface of the semiconductor package is measured by the same method as the average interval (Sm) of the unevenness on the surface of the release layer.

The average length (RSm) of the roughness curve elements on the surface of the semiconductor package is preferably 0.12 mm or less, more preferably 0.10 mm or less, and still more preferably 0.08 mm or less. The lower limit of the average length (RSm) of the surface roughness curve elements of the semiconductor package is not particularly limited, but may be 0.01 mm or more, 0.03 mm or more, or 0.05 mm or more, for example. The average length (RSm) of the roughness curve elements on the surface of the semiconductor package is measured by the same method as the average length (RSm) of the roughness curve elements on the surface of the release layer.

The maximum height (Ry) of the surface of the semiconductor package is preferably 1.0 μm or more, more preferably 2.0 μm or more, further preferably 5.2 μm or more. The upper limit of the maximum height (Ry) of the surface of the semiconductor package is not particularly limited. For example, it may be 30.0 μm or less, 20.0 μm or less, or 10.0 μm or less. The maximum height (Ry) of the surface of the semiconductor package is measured by the same method as the maximum height (Ry) of the surface of the release layer.

The difference between the 10-point average roughness (Rz) and the maximum height (Ry) of the surface of the semiconductor package (molded product) is preferably 3.00 μm or less, more preferably 2.50 μm or less, and still more preferably 2.00 μm or less. The difference is preferably 0.50 μm or more, more preferably 1.00 μm or more, still more preferably 1.50 μm or more.

The glossiness (20°) of the surface of the semiconductor package is preferably 8.0 or less, more preferably 5.0 or less, and still more preferably 3.0 or less. The lower limit of the glossiness (20°) of the surface of the semiconductor package is not particularly limited. For example, it may be 0.3 or more, 0.5 or more, or 1.0 or more.

The glossiness (60°) of the surface of the semiconductor package is preferably 30.0 or less, more preferably 20.0 or less, and still more preferably 15.0 or less. The lower limit of the glossiness (60°) of the surface of the semiconductor package is not particularly limited. For example, it may be 1.0 or more, 3.0 or more, or 5.0 or more.

The glossiness (85°) of the surface of the semiconductor package is preferably 65.0 or less, more preferably 50.0 or less, and still more preferably 30.0 or less. The lower limit of the glossiness (85°) of the surface of the semiconductor package is not particularly limited. For example, it may be 1.0 or more, 5.0 or more, or 10.0 or more.

The glossiness of the surface of the semiconductor package is measured by the same method as the glossiness of the surface of the release layer. [Example]

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not limited to these examples.

(Synthesis of Resin A and Resin B) The monomers shown in Table 1 below were copolymerized by solution polymerization using the blending amounts (parts by mass) shown in Table 1, to obtain resin A and resin B. For the obtained resin A and resin B, the number average molecular weight Mn and the weight average molecular weight Mw were measured in terms of standard polystyrene by gel permeation chromatography (GPC). Table 1 shows the SP values of the obtained resin A and resin B.

[Table 1] monomer Resin A Resin B BA 92 53 4-HBA 8 0 2-HEMA 0 4 AN 0 43 Mn 144,000 610,000 MW 854,000 140,000 SP value 10.0 11.0

The monomers in Table 1 represent the following. ・BA: Butyl acrylate ・4-HBA: 4-hydroxybutyl acrylate ・2-HEMA: 2-hydroxyethyl methacrylate ・AN: Acrylonitrile

<Example 1> What added 20 parts by mass of a difunctional/trifunctional polyisocyanate mixture as a crosslinking agent to 100 parts by mass of the total compounding amount of resin A (30 parts by mass) and resin B (70 parts by mass) was added to A toluene solution with a solid content of 15% by mass was prepared from toluene to prepare a release layer forming composition. As the base material layer, a biaxially stretched polyethylene terephthalate film (Unitika Co., Ltd.: S-38) with a thickness of 38 μm was used, and corona treatment was performed. Then, a release layer-forming composition was applied to one side of the base material layer using a roll coater so that the average thickness after drying became 5 μm, and dried to form a release layer, thereby obtaining a release film.

<Example 2 to Example 7> A release film was obtained in the same manner as in Example 1, except that the types and addition amounts of the resin and crosslinking agent were changed as shown in Table 2. The numerical values of the resin, cross-linking agent, and filler in Table 2 represent the compounding amounts (parts by mass).

＜Comparative example 1＞ The same conditions as in Examples were used except that the crosslinking agent was 20 parts by mass relative to resin A (100 parts by mass) and 10 parts by mass of polymethyl methacrylate particles (average particle diameter 3 μm) were used as fillers. 1 Make a release film in the same way.

<Comparative Example 2, Comparative Example 3> A release film was produced in the same manner as in Comparative Example 1 except that the filler amount was changed as shown in Table 2.

＜Evaluation test＞ (Measurement of the surface state of the release layer) By the method described above, the proportion (area %) of the recessed portions in the surface of the release layer of the release film was determined using image processing using a digital microscope VHX-7000 manufactured by Keyence Co., Ltd. . In addition, the arithmetic average roughness (Ra), the 10-point average roughness (Rz), the average interval of unevenness (Sm), and the average length of the roughness curve elements (RSm) on the surface of the release layer of the release film , and maximum height (Ry) are measured. "Surface roughness measuring instrument SE-3500" manufactured by Kosaka Laboratory Co., Ltd. was used for the measurement. The results are shown in Table 2.

(Glossiness of the release layer) By the above method, the glossiness (20°, 60°, and 85°) of the surface of the release layer of the release film was measured. The results are shown in Table 2.

(Surface roughness of molded product) The release film is placed so that the sealing material (Showa Denko Materials Co., Ltd.: trade name "CEL-9750ZHF10") is attached to the release layer side of the release film, and by heating and pressurizing with a hydraulic press, the release film is pressed at a temperature of 180 ℃ and a hardening time of 5 minutes to produce a molded product of the sealing material. Then, the release film was peeled off from the molded product of the sealing material, and the surface of the obtained molded product of the sealing material was evaluated for the arithmetic mean roughness (Ra) and the 10-point average using the same method as the surface roughness of the release layer. The roughness (Rz), the average interval between concavities and convexities (Sm), the average length of the roughness curve elements (RSm) and the maximum height (Ry) were measured. The results are shown in Table 2.

(Glossiness of molded products) By the above method, the glossiness (20°, 60°, and 85°) of the surface of the molded product was measured. The results are shown in Table 2.

(Transfer rate) The transfer rate was determined using the arithmetic mean roughness (Ra) of the surface of the release film obtained by the above method and the arithmetic mean roughness (Ra) of the surface of the molded article. The results are shown in Table 2.

[Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative example 1 Comparative example 2 Comparative example 3 Resin A 30 20 20 15 15 10 10 100 100 100 B 70 80 80 85 85 90 90 Cross-linking agent 20 10 20 10 20 10 20 20 20 20 filler 10 5 3 Transfer rate (%) 104 122 142 142 127 131 134 46 56 55 Proportion of concavity on the surface (area %) 38 twenty four 27 14 12 10 9 78 90 95 Release layer Roughness Ra（μm） 0.78 0.53 0.55 0.36 0.42 0.22 0.25 0.69 0.45 0.35 RZ(μm) 5.00 4.07 4.08 2.54 3.52 2.14 2.33 5.73 4.48 4.33 Sm(mm) 0.10 0.19 0.07 0.06 0.07 0.09 0.10 0.06 0.08 0.17 RSm(mm) 0.09 0.06 0.06 0.05 0.05 0.06 0.06 0.04 0.06 0.09 Ry(μm) 5.60 4.60 4.70 3.50 4.10 2.70 3.00 6.57 5.21 4.96 Glossiness 20° 18.5 14.7 11.8 15.8 14.7 25.6 20.2 28.3 44.7 63.3 60° 29.5 21.2 19.5 25.2 25.4 42.7 40.3 44.3 64.8 76.7 85° 33.2 30.5 29.8 42.3 34.9 54.0 57.8 39.1 56.8 58.6 (Ry-RZ) 0.60 0.53 0.62 0.96 0.58 0.56 0.67 0.84 0.73 0.63 Molded products Roughness Ra (μm) 0.81 0.65 0.78 0.51 0.54 0.28 0.33 0.32 0.25 0.19 Rz (μm) 4.81 4.47 5.16 3.90 3.73 2.88 2.76 3.78 2.78 2.30 Sm(mm) 0.11 0.10 0.10 0.15 0.08 0.17 0.10 0.37 0.35 0.51 RSm(mm) 0.10 0.08 0.08 0.09 0.07 0.08 0.07 0.13 0.18 0.19 Ry(μm) 5.61 5.30 6.39 5.45 4.43 3.99 3.24 5.02 3.33 3.14 Glossiness 20° 3.8 0.9 1.0 1.1 1.1 2.1 2.4 8.9 15.5 22.5 60° 18.6 8.5 8.2 10.1 9.9 17.2 16.9 30.8 46.9 60.8 85° 33.5 18.2 14.6 26.9 22.8 53.3 42.4 65.5 84.6 91.3 (Ry-RZ) 0.79 0.83 1.22 1.56 0.70 1.11 0.48 1.24 0.55 0.84

As shown in the results of Table 2, it was found that the release films of Examples 1 to 7 had an effective reduction in glossiness and an excellent flow mark reduction effect compared to the release films of Comparative Examples 1 to 3.

10:Substrate layer 20: Release layer 30: Release film

FIG. 1 is a schematic cross-sectional view showing the structure of a release film. FIG. 2 is a photograph and an analysis chart of the surface of the release layer using a laser microscope. Figure 3 is a spectrum result obtained by analyzing the components of the discontinuous phase (island phase, convex parts) and the continuous phase (marine phase, concave parts) in sample G2 in Figure 2 using micro-Raman spectroscopy. Figure 4 is a spectrum result obtained by analyzing the components of the discontinuous phase (island phase, concave parts) and the continuous phase (marine phase, convex parts) in sample G3 in Figure 2 using micro-Raman spectroscopy. FIG. 5 is a plan view showing the shape of a test piece used for measuring the elongation at break of the release film.

10:Substrate layer

20: Release layer

30: Release film

Claims (14)

A release film, including a release layer and a base material layer, The release layer contains two or more polymers, and the surface of the release layer has an uneven shape, When the surface of the release layer is viewed in a plan view, the proportion of the recessed portions in the surface is 50 area % or less. A release film, including a release layer and a base material layer, The release layer contains two or more polymers, and the surface of the release layer has an uneven shape, The percentage of the arithmetic mean roughness (Ra) of the surface of the molded article relative to the arithmetic mean roughness (Ra) of the surface of the mold release layer when the uneven shape of the release layer is transferred to the molded article is: The transfer rate is over 100%. A release film, including a release layer and a base material layer, The release layer contains two or more polymers, and the surface of the release layer has an uneven shape, When the uneven shape of the release layer is transferred to the molded article, the glossiness (20°) of the surface of the molded article is 8.0 or less. The release film according to claim 1, wherein at least one of the polymers is a nitrile group-containing (meth)acrylic polymer. The release film according to claim 1, wherein when the irregularities on the surface of the release layer are measured by Raman spectroscopy, different peak intensities are shown in at least a part of the convex portions and at least a part of the concave portions. . The release film according to claim 1, wherein the component ratio of the polymer in the convex portions of the surface of the release layer is different from the component ratio of the polymer in the recessed portions. The release film according to claim 6, wherein the mass-based content of the nitrile group-containing (meth)acrylic polymer in the convex portion is greater than the nitrile group-containing (meth)acrylic polymer in the recessed portion. ) acrylic polymer has a large content on a mass basis. The release film according to claim 1, wherein the difference in solubility parameter values among at least two of the polymers is 0.3 or more. The release film according to claim 1, wherein at least one of the polymers is a polymer containing a structural unit derived from (meth)acrylonitrile monomer, In at least two types of the polymers, the difference in the proportions of structural units derived from (meth)acrylonitrile monomer is 1 mass % or more. The release film according to claim 1, wherein the content rate of the most abundant polymer in the release layer is 95 mass % or less relative to the total content of the polymer. The release film according to claim 1, wherein the base material layer is a polyester film. The release film according to claim 1, wherein the thickness of the release layer is 1 μm to 50 μm. The release film according to claim 1, wherein the release film is used for transfer molding or compression molding. A manufacturing method of a semiconductor package, using the release film according to any one of claims 1 to 13 to perform a transfer molding step or a compression molding step.