Release film for semiconductor molding

Abstract

To provide a release film for semiconductor molding that has a good perforation property with a needle, a laser, etc., and can suppress film bulging at the mold guide pin area.SOLUTION: A release film for semiconductor molding has a bending stiffness of 10×10-3 (N mm2) or more and 150×10-3 (N mm2) or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a release film used in semiconductor molding, and in particular, can be suitably used as a release film disposed between the die of a semiconductor molding device and the lower part of a silicon wafer. [Background technology]

[0002] Semiconductor chips are sealed with resin to protect them from disturbances such as light, heat, moisture, and physical shocks, and are mounted on a substrate as a molded product called a package. Hardening resins such as epoxy resins are used to seal semiconductor chips. The so-called transfer molding method and compression molding method are known as methods for sealing semiconductor chips, but in recent years, the introduction of the compression molding method has been progressing against the backdrop of trends such as larger semiconductor wafers, thinner packages, and more pins to increase the number of input terminals.

[0003] The compression molding method is a method in which a molten encapsulating resin is compressed and hardened by moving a mold up and down while being heated, and is used as a manufacturing method for an ultra-small package technology called wafer-level chip size package (WL-CSP). In this case, a release film is generally inserted to ensure the releasability of the mold and the encapsulating resin. As the release film, a film of ethylene-tetrafluoroethylene copolymer (ETFE) has been widely used because of its excellent releasability, heat resistance, and conformability to the mold shape. However, since the gas generated from the hardening molding resin is highly permeable and easily contaminates the mold, materials with low gas permeability, mainly polyester, are being investigated (Patent Documents 1 and 2).

[0004] Among polyester films, in the case of release films based on polyethylene terephthalate (PET) film, which has excellent dimensional stability, it is necessary to provide a release layer in addition to the base film, and a method is often used in which particles or other components that impart roughness are added to the release layer to impart design properties (Patent Document 3).

[0005] In recent years, fan-out wafer-level package (FO-WLP) technology, in which the package size is larger than the chip size, has become more common in order to expand the area in which the input terminals of the package are located. Figure 1 shows a schematic diagram of the face-up compression molding process used to manufacture FO-WLP, but because full molding allows the molding resin to reach the edges of the metal mold, the edges on the bottom side of the wafer become contaminated by the molding resin. To prevent this, a release film is sometimes placed on the bottom side of the silicon wafer as well.

[0006] In these processes, suction is applied through suction holes to fix the silicon wafer and the mold in place, so holes are sometimes made in the release film in advance with a needle or laser to avoid blocking the suction holes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-158242 A [Patent Document 2] JP 2016-92272 A [Patent Document 3] JP 2016-92271 A Summary of the Invention [Problem to be solved by the invention]

[0008] It was found that when the polyester-based release films described in Patent Documents 1 to 3 are used as release films for semiconductor molds, the film may have too high rigidity, causing the film located at the guide pin to bulge like a tent, pushing up the mold resin around the film, resulting in a problem of thinning the thickness of the resin, or the mold resin may move to the back side of the silicon wafer, etc. It was also found that when drilling holes with a carbon dioxide laser, needle, etc., the high rigidity makes it difficult to drill holes in the film, causing problems such as contamination by film debris due to the generation of burrs, and difficulty in fixing the silicon wafer.

[0009] Therefore, an object of the present invention is to provide a release film for a semiconductor mold which has good drilling properties with a needle or the like and which can suppress protrusion of the film at the guide pin portion. [Means for solving the problem]

[0010] In order to solve the above problems, a preferred embodiment of the release film for a semiconductor mold of the present invention has the following configuration. (1) Bending rigidity is 10 x 10 -3 (N mm 2 ) or more 150 x 10 -3 (N mm 2 ) or less. (2) Oxygen permeability is 1 (cc / m 2 / day) or more 1000(cc / m) 2 / day) or less. (3) A release film for a semiconductor mold according to (1) or (2), which has a structure in which at least a release layer and a base film are laminated in this order. (4) The release film for a semiconductor mold according to (3), wherein the base film is mainly composed of a polyester resin. (5) The release film for a semiconductor mold according to (4), wherein the polyester resin contains 0.5 mol % or more and 20 mol % or less of a cyclohexanedimethanol residue, a 1,4-butanediol residue, or a 1,3-propanediol residue in the diol component. (6) The release film for a semiconductor mold according to (4) or (5), wherein the base film contains 0.1 mass % or more and 3.0 mass % or less of polyalkylene glycol. (7) The release film for a semiconductor mold according to (6), wherein the polyalkylene glycol is polyethylene glycol. (8) The release film for a semiconductor mold according to any one of (4) to (7), wherein the polyester resin contains 0.5 mol % or more and 20 mol % or less of an isophthalic acid residue in a dicarboxylic acid component. (9) The release film for a semiconductor mold according to any one of (3) to (8), wherein the release layer is a thermosetting long-chain alkyl-based composition. (10) A release film for a semiconductor mold according to any one of (3) to (9), wherein the release layer has a 31B tape peel strength of 1.0 N / mm or less after heating at 170° C. (11) The release film for a semiconductor mold according to any one of (1) to (10), which has a piercing strength of 2 N or more and 6 N or less. (12) The release film for a semiconductor mold according to any one of (1) to (11), having a Young's modulus in both the longitudinal and transverse directions of 1.5 GPa or more and 3.0 GPa or less. (13) The release film for a semiconductor mold according to any one of (1) to (12), having a through hole α, where the through hole α has a maximum diameter of more than 0.1 mm and not more than 20.0 mm. (14) In a chart showing the dynamic friction coefficient when the release layer surfaces of the release film for semiconductor molds are rubbed against each other, the vertical axis is the load and the horizontal axis is the displacement, the point at which the relative slippage between the contact surfaces begins is D0, and the point at which the contact surface moves 60 mm from D0 is D 60 , D0 and D 60 The maximum load between FD max (g) D0 and D 60 The minimum load between FD min(g), F.D. max (g) and FD min The release film for a semiconductor mold according to (13), wherein the difference between (g) and ΔFD(g) is 0.1 g or more and 200 g or less. (15) The release film for a semiconductor mold according to any one of (1) to (14), wherein the molding method is a compression method. (16) A release film for a semiconductor mold according to any one of (1) to (15) above, which is disposed between a mold and a lower part of a semiconductor in a semiconductor molding device. Effect of the Invention

[0011] According to the present invention, it is possible to provide a release film for a semiconductor mold which has good drilling properties with a needle or the like and which can suppress protrusion of the film at the guide pin portion. [Brief description of the drawings]

[0012] [Figure 1] Schematic diagram of the face-up compression molding process in which the lower die with the Si wafer placed on it rises. [Diagram 2] Schematic diagram of vacuum forming using a vacuum forming machine when measuring the tent diameter using a mold. [Diagram 3] Specific examples of the shape of the through hole α. [Figure 4] This is a schematic chart showing the displacement on the horizontal axis and the friction coefficient on the vertical axis when the release layer surfaces are rubbed together and the friction coefficient is measured in accordance with JIS-K7125 (1999). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The release film for a semiconductor mold of the present invention may have a single-layer structure, but it is preferable that the release film for a semiconductor mold of the present invention is composed of a base film having releasability and other functions separated therefrom, and a release layer, in view of high design freedom.

[0014] <Base film composition and structure> When the substrate film of the present invention is constructed as a single layer, it is preferable to use a resin that has low gas permeability, good releasability, and excellent flexibility for needle drilling and mold tracking. For example, polyolefin resins are preferable, and among them, polystyrene, polymethylpentene, polypropylene, ethylene propylene copolymer, ethylene propylene butene copolymer, etc. are preferable resins. It is also a preferable embodiment to add a plasticizer or alpha olefin to these resins. When constructed as a single layer, both sides of the film also function as release layers.

[0015] When the release film for semiconductor mold of the present invention is composed of a base film and a release layer, it is preferable that the base film is made of a biaxially stretchable resin such as polyamide or polyester from the viewpoints of productivity and oxygen permeability. In the present invention, it is particularly preferable that the base film is mainly composed of polyester resin. Here, the main component of the film is polyester resin, which means that the polyester resin is contained in an amount of more than 60 mass% of the components constituting the film. The use of polyester resin can particularly reduce gas permeability.

[0016] Polyester resins can be obtained by 1) polycondensation of dicarboxylic acids or their ester derivatives (hereinafter collectively referred to as "dicarboxylic acid components") and diol components or their ester derivatives (hereinafter collectively referred to as "diol components"); 2) polycondensation of a compound having a carboxylic acid and a hydroxyl group in one molecule or a compound having a carboxylic acid derivative and a hydroxyl group; and a combination of 1) and 2).

[0017] In 1), examples of the dicarboxylic acid component include aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, eicosanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, and ethylmalonic acid; alicyclic dicarboxylic acids such as adamantanedicarboxylic acid, norbornenedicarboxylic acid, cyclohexanedicarboxylic acid, and decalindicarboxylic acid; terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid; Representative examples include aromatic dicarboxylic acids such as dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, and 9,9'-bis(4-carboxyphenyl)fluorene acid, or ester derivatives thereof. These may be used alone or in combination.

[0018] Also usable are dicarboxy compounds in which hydroxy acids such as l-lactide, d-lactide, hydroxybenzoic acid, and derivatives thereof, or a combination of multiple hydroxy acids are condensed to at least one carboxy terminal of the above-mentioned dicarboxylic acid component.

[0019] Next, as the diol component, representative examples include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, and 1,3-butanediol, alicyclic diols such as cyclohexanedimethanol, spiroglycol, and isosorbide, and aromatic diols such as bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9'-bis(4-hydroxyphenyl)fluorene. These may be used alone or in combination as necessary. Dihydroxy compounds formed by condensing diols to at least one hydroxyl terminal of the above-mentioned diol component may also be used.

[0020] On the other hand, in the case of 2), examples of compounds having a carboxylic acid or a carboxylic acid derivative and a hydroxyl group in one molecule include oxyacids such as l-lactide, d-lactide, hydroxybenzoic acid, and their derivatives, oligomers of oxyacids, and dicarboxylic acids condensed with one of the carboxyl groups of the oxyacid.

[0021] Specific examples of polyester resins include homopolymers such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, and polylactic acid, as well as copolymers thereof. The polyester resin constituting the polyester film of the present invention may be one selected from the above homopolymers and copolymers, or a blend of homopolymers or a blend of a homopolymer and a copolymer may be used.

[0022] Here, the homopolymer of the polyester resin is preferably one selected from polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, and polylactic acid from the viewpoint of film-forming properties, and among these, polyethylene terephthalate or polyethylene-2,6-naphthalate is more preferable from the viewpoint of ease of processability, and polyethylene terephthalate is particularly preferable from the viewpoint of design properties.

[0023] A polyester resin copolymer refers to a polymer in which less than 50 mol % of the entire polyester resin is composed of either or both of different dicarboxylic acid components and diol components. When a blend with a homopolymer is envisaged, it is preferable to use a copolymer in which 50 mol % or more of the entire polyester resin contains the same molecular structure as the target homopolymer.

[0024] Here, as the polyester resin copolymer, from the viewpoint of excellent polymerization suitability, thermal stability, and compatibility with homopolymers, it is preferable to use one that contains, as the dicarboxylic acid component, an alicyclic dicarboxylic acid, isophthalic acid, or naphthalene dicarboxylic acid, and as the diol component, butanediol, ethylene glycol, spiroglycol, or cyclohexanedimethanol as a copolymer component, and these may be used alone or in combination as necessary.

[0025] In addition, in the polyester resin constituting the base film of the release film of the present invention, the amount of isophthalic acid residues relative to the dicarboxylic acid component is preferably 0.5 mol% or more and 20 mol% or less, since it is easy to control the bending rigidity to the range of the present application while maintaining a low oxygen permeability, and the moldability of the release film in molding processing using a mold can be improved. Note that the moldability is different from the hole-making processability using a needle or the like, and refers to the mold followability during molding processing. In addition, it is preferable to set the amount of isophthalic acid residues to 10 mol% or less, since it is possible to suppress the decrease in transfer efficiency of unevenness due to excessive softening and improve the design. From the same viewpoint, the amount of isophthalic acid residues is more preferably 1.0 mol% or more and 7.0 mol% or less, and even more preferably 1.5 mol% or more and 3.0 mol% or less. Also, in view of the fact that similar effects can be expected, the polyester resin preferably contains 0.5 mol% or more and 20 mol% or less of cyclohexanedimethanol residues, 1,4-butanediol residues, or 1,3-propanediol residues in the diol component, more preferably contains 5.0 mol% or more and 17 mol% or less of cyclohexanedimethanol residues, 1,4-butanediol residues, or 1,3-propanediol residues in the diol component, and even more preferably contains 8.0 mol% or more and 15 mol% or less of cyclohexanedimethanol residues, 1,4-butanediol residues, or 1,3-propanediol residues in the diol component.

[0026] When the polyester resin is used as the main component of the substrate film, it is preferable that the polyester resin contains polyalkylene glycol as a softening component, from the viewpoint of easily controlling the bending rigidity within the range of the present application while maintaining a low oxygen permeability. As the polyalkylene glycol, polyethylene glycol, polypropylene glycol, and polybutylene glycol are preferable, and polyethylene glycol is more preferable because it has a high decomposition temperature and is easy to melt-knead with the polyester resin and solids. It is preferable that the content of the polyalkylene glycol is 0.1 mass% or more in 100 mass% of the substrate film, since it can further improve the moldability. In addition, it is preferable that the content of the polyalkylene diol component is 3.0 mass% or less in 100 mass% of the substrate film, since it can suppress poor release caused by the thermal decomposition of the polyalkylene diol component, and it can suppress the decrease in transfer efficiency of unevenness due to excessive softening, and can improve the design. From the same viewpoint, the content of the polyalkylene diol component is more preferably 0.3 mass % or more and 2.0 mass % or less, and further preferably 0.5 mass % or more and 1.0 mass % or less, based on 100 mass % of the base film.

[0027] The amount of the copolymerized component residues and the amount of the added components were measured by proton nuclear magnetic resonance spectroscopy ( 1 H-NMR) and carbon nuclear magnetic resonance spectroscopy ( 13 The analysis can be carried out by known techniques such as C-NMR.

[0028] In the present invention, it is preferable that the substrate film is composed of at least a main layer and a sub-layer. This configuration makes it easier to maintain film-forming stability and moldability. The release film may be composed in the order of release layer / sub-layer / main layer. As long as the configuration is as described above, the sub-layer may be a three-layer laminated configuration of sub-layer / main layer / sub-layer in which the sub-layer is laminated on both sides of the main layer, or a multiple laminated configuration of 3 to 10,000 layers may be alternately formed. In addition, when the sub-layer is formed on the back side opposite to the release layer side (such as a configuration of release layer / sub-layer / sub-layer / sub-layer), air can be easily removed when the release film and the mold are adsorbed and fixed by vacuum drawing, and wrinkles can be suppressed, so that the film can be particularly preferably used in the face-down method. In addition, the most preferable configuration for achieving both film-forming stability and moldability is that the main layer is a layer that emphasizes moldability containing a large amount of soft components, and the sub-layer is functionally separated without containing any components that contribute to the above-mentioned moldability. That is, the main layer preferably contains 0.5 mol% to 20 mol% of isophthalic acid residues relative to the dicarboxylic acid component of the polyester resin of the layer, and / or 0.5 mol% to 20 mol% of cyclohexanedimethanol residues, 1,4-butanediol residues, or 1,3-propanediol residues in the diol component of the polyester resin of the layer, and more preferably contains polyalkylene glycol. Also, the sub-layer preferably contains less than 0.5 mol% of isophthalic acid residues relative to the dicarboxylic acid component of the polyester resin of the layer, and less than 0.5 mol% of cyclohexanedimethanol residues, 1,4-butanediol residues, or 1,3-propanediol residues in the diol component of the polyester resin of the layer, and the content of polyalkylene glycol is less than 0.1 mass% in 100 mass% of the layer.

[0029] The lamination ratio of the sub-layer to the main layer is not limited, but if film-forming stability and moldability are important, it is preferable to increase the ratio of the main layer. For example, the lamination ratio in the thickness direction of the sub-layer:main layer=1:1 to 1:40 can be mentioned. The absolute thickness value of the sub-layer is preferably 1 μm or more from the viewpoint of air escape, and is preferably less than 20 μm from the viewpoint of film-forming stability. Regarding the thickness ratio of each layer, for example, in the case of release layer / sub1 / main / sub2, the sum of the thicknesses of sub1 and sub2 is the sub-layer, and even in the case of sub3, 4, etc., the sum of the thicknesses of each sub-layer is the sub-layer.

[0030] In the release film of the present invention, the particle content of the base film is preferably 0.1% by mass or more for the purpose of imparting air escape properties. The particle content of the base film is more preferably 0.3% by mass or more and 26% by mass or less, further preferably 1.0% by mass or more and 23% by mass or less, and particularly preferably 3.0% by mass or more and 18% by mass or less. In particular, a particle content of more than 10% by mass is preferable because it improves slipperiness and improves air escape properties, thereby reducing the tent diameter.

[0031] <Method of manufacturing base film> The base film of the release film of the present invention is preferably a biaxially oriented film. Biaxial orientation allows the mechanical properties to be adjusted according to the molding method and reduces thickness unevenness. Here, the biaxially oriented film can be obtained by stretching an unstretched film obtained by any conventionally known method in the longitudinal direction and then in the width direction, or by stretching in the width direction and then in the longitudinal direction by a sequential biaxial stretching method, or by stretching in the longitudinal direction and the width direction of the film almost simultaneously by a simultaneous biaxial stretching method. Here, biaxial orientation refers to a state in which an unstretched (unoriented) film is stretched in two dimensions by a conventional method, and refers to a case in which one or more of the following a to d are satisfied. a: Wide-angle X-ray diffraction shows a biaxially oriented pattern. b: Evaluation method (3) Using the method described in Young's modulus, mechanical properties are measured in two directions, one direction and the other perpendicular to the direction, and the Young's modulus obtained is 500N / mm2 That's all. c: It can be determined that biaxial orientation is achieved by the method described in Evaluation method (23) Determination of biaxial orientation state by laser Raman spectroscopy. d: The MOR measured by a molecular orientation analyzer is 1.2 or more.

[0032] MOR represents the ratio of the maximum and minimum dielectric constants in the in-plane direction of the film, and in the case of biaxially oriented films in particular, it is an index showing that the orientation and crystallization of the film increases as the MOR value increases. When the MOR is 1.2 or higher, the biaxial orientation of the film has progressed and the film is in a biaxially oriented state.

[0033] In the case of using a polyester resin, the stretching ratio in the stretching method is preferably 2.7 to 3.6 times in the longitudinal direction, more preferably 3.0 to 3.4 times in the longitudinal direction. The stretching temperature in the longitudinal direction is preferably 70° C. to 90° C. The stretching ratio in the transverse direction is preferably 3.0 to 5.0 times in the transverse direction, more preferably 3.2 to 4.0 times in the transverse direction.

[0034] Furthermore, it is preferable to heat treat the film after biaxial stretching. The heat treatment can be performed by any conventionally known method such as in an oven. This heat treatment is preferably performed in a temperature atmosphere of Tm-40°C or more and Tm-5°C or less, where Tm is the temperature at which the crystal melting enthalpy is the largest among the crystal melting peak temperatures of the film. By setting the heat treatment temperature to Tm-40°C or more, the stretching stress can be sufficiently relaxed, and the moldability during compression molding can be improved in particular. In addition, by setting the heat treatment temperature to Tm-5°C or less, the film formation stability is improved. From the same viewpoint, the heat treatment temperature is more preferably Tm-30°C or more and Tm-8°C or less, and even more preferably Tm-20°C or more and Tm-10°C or less.

[0035] The heat treatment time can be any time within a range that does not deteriorate the characteristics, but it is preferable to set it to 5 seconds or more and 60 seconds or less, since this can enhance the effect of the heat treatment temperature described above. From the same viewpoint, the heat treatment time is more preferably 7 seconds or more and 40 seconds or less, and further preferably 10 seconds or more and 25 seconds or less.

[0036] <Release layer composition and structure> The release layer in the present invention preferably contains a binder resin, since this improves adhesion to the base film and also allows the release force to be adjusted. Specific examples of the binder resin include polyester resin, polystyrene resin, acrylic resin, urethane resin, polyvinyl, polyalkylene glycol, polyalkyleneimine, cellulose, and starch compositions.

[0037] In addition, it is preferable to add a crosslinking agent as a component constituting the release layer. By using various crosslinking agents in combination with the above-mentioned resin, the heat resistance can be dramatically improved. The crosslinking agent is preferably one or more selected from oxazoline resin, melamine resin, epoxy resin, carbodiimide resin, and isocyanate resin. From the viewpoint of the durability of the release layer to the solvent, melamine resin is more preferably used. The crosslinking agents can be mixed and used in any ratio, but the addition of 5 parts by mass or more and 50 parts by mass or less of the crosslinking agent to 100 parts by mass of the binder resin is preferable from the viewpoint of improving the release property, and more preferably 10 parts by mass or more and 40 parts by mass or less. If the amount of the crosslinking agent added is less than 5 parts by mass, the effect of the release property may be insufficient, or scratches may occur during roll transport. Also, if it exceeds 50 parts by mass, spots are likely to occur during application, which may result in a decrease in the release property, which may not be preferable.

[0038] In the present invention, it is preferable that the resin composition forming the release layer contains an additive suitable for the purpose of imparting releasability in addition to the binder resin and the crosslinking agent. The additive is preferably 3 parts by mass or more and 50 parts by mass or less when the sum of the masses of the binder resin and the crosslinking agent is 100 parts by mass. By making the mass of the additive 3 parts by mass or more, it is possible to impart releasability, and by making it 50 parts by mass or less, it is possible to impart heat resistance to the release layer that can withstand compression molding, and as a result, it is possible to suppress the decrease in releasability. It is preferably 10 parts by mass or more and 42 parts by mass or less, and most preferably 20 parts by mass or more and 34 parts by mass or less.

[0039] The additive in the present invention refers to a compound that has a releasing property on the surface of the resin by adding it to the resin. Specific examples include silicone-containing compounds, fluorine compounds, waxes such as paraffin wax, polyethylene wax, and carnauba wax, compounds containing long-chain alkyl groups, and resins. Among them, compounds containing long-chain alkyl groups are preferred from the viewpoint of releasing properties and suppressing poor appearance. The long-chain alkyl compound in the present invention refers to a compound having a long-chain alkyl group, and is not particularly limited as long as it contains a long-chain alkyl group, but examples thereof include compounds having a long-chain alkyl group on the side chain of the main chain polymer. That is, the release layer in the present invention is preferably a thermosetting long-chain alkyl composition.

[0040] In the compound having a long-chain alkyl group on the side chain of the main chain polymer, examples of the main chain polymer include acrylate polymers or copolymers, polyvinyl alcohol (including partially saponified polyvinyl acetate), ethylene-vinyl alcohol copolymers (including partially saponified ethylene-vinyl acetate copolymers), vinyl alcohol-acrylic acid copolymers (including partially saponified vinyl acetate-acrylic acid copolymers), polyethylimine, polyvinylamine, styrene-maleic anhydride copolymers, polyurethanes, etc. In the present invention, from the viewpoint of heat resistance, compounds having a thermosetting long-chain alkyl group are preferred.

[0041] In the present invention, when the release layer is provided, it has excellent releasability, particularly for granular molding resins having relatively low resin fluidity, and is therefore preferably used as a release film for granular molding resins.

[0042] <Method of forming release layer> A preferred embodiment of the release film of the present invention is characterized in that a release layer is provided on one or both sides of a base film.

[0043] Providing a release layer on only one side of the substrate film is preferred because it can shorten the manufacturing process of the release layer, whereas providing a release layer on both sides of the substrate film is preferred because it imparts releasability to the mold side as well, and it is possible to prevent precipitated oligomers and the like from adhering to the mold.

[0044] The method of providing a release layer on a substrate film includes dissolving or dispersing the resin composition of the release layer in a solvent, applying it to the substrate film, drying the solvent after application, and heating it; melt-co-extruding the resin composition of the release layer together with the substrate film and forming it into a sheet together with the substrate film by the above-mentioned method; extruding the molten resin composition of the release layer onto a substrate film that has been subjected to processing such as corona treatment to provide a resin layer; and laminating a substrate film and a release layer that have been separately manufactured. Among these, the method of providing a release layer by coating is preferred from the viewpoint of being able to freely select the above-mentioned preferred binder resin, additives, and crosslinking agent.

[0045] The method of applying the release layer to the base film is preferably a method of applying the release layer uniformly with a metaling bar or gravure roll, and then drying in an oven. When applying by a coating method such as gravure coating, it is preferable to apply the release layer so as not to inhibit the flow and flattening (leveling) of the coating layer. The oven temperature is preferably 70 to 245°C, more preferably 80 to 235°C, and most preferably 90 to 225°C. If the drying temperature is lower than 70°C, the release layer may not be cured sufficiently, and the base film and the release layer may not adhere to each other. In addition, if the temperature is higher than 245°C, the coating thickness accuracy may decrease due to thermal deformation of the film. The heat treatment time is preferably 1 to 60 seconds, more preferably 5 to 40 seconds, and most preferably 10 to 30 seconds.

[0046] In the release film of the present invention, in order to ensure stable releasability, the release layer can also be provided by in-line coating. Specifically, in the manufacturing process of the base film, a method is preferred in which a resin composition of the release layer is dissolved or dispersed on a film that has been at least uniaxially stretched, and the coating material is uniformly applied using a metering bar or gravure roll, and the coating material is dried while being stretched, and the above method can make the thickness of the release layer more uniform. In addition, by increasing the molecular affinity with the base film, the adhesion between the base film and the release layer can be increased, and the heat treatment at a higher temperature than that of offline coating increases the degree of hardening of the coating film, improving heat resistance and chemical resistance, and at the same time, there is an advantage that aging treatment after manufacturing is unnecessary or can be shortened.

[0047] The release film of the present invention is preferably such that the release layer thickness after drying is 10 nm or more, since the release layer can be maintained to follow the surface shape of the substrate film even when pressure is applied at high pressure such as with a compression mold. Also, it is preferable that the release layer thickness after drying is 2000 nm or less, since the design can be improved without impairing the uneven shape of the substrate film. From the same viewpoint, the release layer thickness after drying is more preferably 50 nm or more and 1500 nm or less, and even more preferably 100 nm or more and 1200 nm or less.

[0048] <Film characteristics> The release film for semiconductor mold of the present invention has a bending stiffness of 10×10 -3 (N mm 2 ) or more 150 x 10 -3 (N mm 2 ) or less. When the film has a bending rigidity within this range, when the film is used as the lower release film shown in FIG. 1 in a molding method using guide pins or the like, film bulging caused by guide pins during semiconductor molding can be suppressed, and the thinning defect of the resin at the mold end can be suppressed. The degree of film bulging is sometimes expressed as the tent diameter shown in FIG. 1. The smaller the tent diameter, the better. The tent diameter is preferably 50 mm or less. The tent diameter can be measured by the method described in the examples. From the viewpoint of suppressing film bulging, the tent diameter is preferably 30 mm or less, and most preferably 15 mm or less. In addition, the film has excellent hole drilling processability with a laser, needle, or the like for the purpose of adsorption to the suction hole. The film has a bending rigidity of 10×10 -3 (N mm 2 ), the film's rigidity is too low, and the film may break during molding, or wrinkles may form in the film during molding, which may transfer to the molding resin and impair the appearance. -3 (N mm 2 ), the resin at the mold edge may become thin due to the film swelling, and the hole drilling processability may be poor. From the viewpoints of reducing the tent diameter due to the film swelling, suppressing wrinkles, and hole drilling processability, it is preferable that the film thickness is 10×10 -3 (N mm 2 ) or more 100 x 10 -3 (N mm 2 ) or less, preferably 12 × 10 -3 (N mm 2 ) or more than 80×10 -3 (N mm 2 ) or less, most preferably 12×10 -3 (N mm 2 ) or more than 60×10 -3 (N mm 2In order to control the bending rigidity within the range of the present invention, for example, the base film may be a biaxially oriented film, and the polyester resin constituting the film may contain 0.5 mol % or more and 20 mol % or less of isophthalic acid residues relative to the dicarboxylic acid component, or the polyester resin may contain 0.5 mol % or more and 20 mol % or less of cyclohexanedimethanol residues, 1,4-butanediol residues, or 1,3-propanediol residues in the diol component.

[0049] The release film for semiconductor molds of the present invention has an oxygen permeability of 1 (cc / m 2 / day) or more 1000(cc / m) 2 / day) or less. By controlling it to this range, it is possible to prevent mold contamination by blocking sublimates derived from the molding resin during semiconductor molding. Mold contamination can be evaluated by the evaluation method described in [Methods for measuring and evaluating characteristics]. From the viewpoint of preventing mold contamination, the oxygen permeability is preferably 1 (cc / m 2 / day) or more 500(cc / m) 2 / day) or less, and 1 (cc / m 2 / day) or more 100(cc / m) 2 / day) or less. Oxygen permeability is most preferably 1000 (cc / m 2 If the oxygen permeability exceeds 100 / day, the mold may be easily contaminated. In order to bring the oxygen permeability into the preferred range of the present invention, it is preferable to use a resin with low oxygen permeability and then perform biaxial orientation. Examples of resins with low oxygen permeability include nylon, polyester, and polypropylene.

[0050] In order to control the bending rigidity to a low level while maintaining the oxygen permeability within the preferred range of the present invention, for example, the above-mentioned polyester resin may be used, the substrate film may be biaxially oriented, and then the film may be heat-treated in an atmosphere at a temperature of Tm-40°C or more and Tm-5°C or less.

[0051] The semiconductor mold release film of the present invention preferably has a piercing strength of 2N or more and 6N or less. By controlling the film within this range, the film has excellent hole opening properties in laser or needle processing. The piercing strength is not uniformly determined by Young's modulus alone. For example, a nylon film, which is a polyamide resin, has a high piercing strength despite having a low Young's modulus compared to a polyester film, and is affected by all of the resin composition, viscosity characteristics, orientation characteristics, and crystallization state. A specific Young's modulus does not necessarily result in a specific piercing strength. In the present invention, in order to achieve a piercing strength of 2N or more and 6N or less while keeping the bending rigidity within the range of the present invention, a preferred method is to use a polyester resin as the main component while keeping the thickness of the substrate film to 35 μm or less, and to use a resin containing cyclohexanedimethanol residue, 1,4-butanediol residue, or 1,3-propanediol residue in an amount of 10 mol% or more and 20 mol% or less of the diol component, and then heat-treating the resin constituting the substrate film after biaxial stretching in a range of Tm-15°C or more and Tm-5°C or less.

[0052] The release film for semiconductor mold of the present invention preferably has a Young's modulus in both the longitudinal and width directions of 1.5 GPa or more and 3.0 GPa or less. By setting the Young's modulus in this range, the film has a moderate rigidity while maintaining the piercing ability in the preferred range, so that the occurrence of wrinkles in the film during molding can be suppressed. Therefore, deterioration of the design due to wrinkle transfer to the mold resin caused by the wrinkles can be suppressed. It is more preferable to set the Young's modulus in both the longitudinal and width directions to 2.0 GPa or more and 3.0 GPa or less, because wrinkles can be suppressed more significantly. Note that if the Young's modulus exceeds 3.0 GPa, the rigidity is too high and the tent diameter caused by the film protuberance may deteriorate.

[0053] In the release film for semiconductor mold of the present invention, the 31B tape peeling force of the release layer after heating at 170°C is preferably 1.0 N / mm or less. The processing temperature for semiconductor molding varies depending on the type of molding resin used and whether it is a compression molding method or a transfer molding method. For example, in a method using a tablet-type molding resin or a transfer molding method, processing may be performed at around 170°C. Therefore, in order to maintain heat resistance that can withstand a method of processing at 170°C or higher, in the present invention, the 31B tape peeling force of the release layer after heating at 170°C is preferably 1.0 N / mm or less. In order to make the 31B tape peeling force 1.0 N / mm or less, it is preferable to provide the release layer.

[0054] The thickness of the release film for semiconductor mold of the present invention is preferably 5 μm or more and 200 μm or less. If it is less than 5 μm, the rigidity is too low, which may cause the film to break and reduce the handling property, or the appearance of the package may be damaged due to wrinkles during molding. On the other hand, if it is 200 μm, the rigidity is too high and the film protuberance of the guide pin may not be suppressed. In consideration of film breakage and protuberance, the thickness is preferably 10 μm or more and 150 μm or less, more preferably 15 μm or more and 100 μm or less, and most preferably 20 μm or more and 75 μm.

[0055] The release film for semiconductor mold of the present invention preferably has a through hole α, when the through hole α is a through hole having a maximum diameter of more than 0.1 mm and not more than 20.0 mm. By having the through hole α, when the film is arranged as a lower release film as shown in FIG. 1, it is preferable that the film can be used in a molding method in which a silicon wafer is fixed by suction from a suction hole on the lower side of a mold, since the fixing of the silicon wafer or the like by suction is not hindered. The through hole α can be formed, for example, by using a laser processing such as carbon dioxide gas, YAG, excimer, or UV, or a punching processing using a needle. Among the processing methods for forming the through hole α in the film of the present invention, it is preferable to use a punching processing method from the viewpoint of economy and mass production. The punching processing method refers to a method of physically forming a through hole using a needle or the like. In addition, it is preferable to use a laser processing method from the viewpoint of reducing burrs when forming a through hole. The laser processing method refers to a method of forming a through hole by irradiating a laser light. The laser processing method itself is well known and can be performed by a conventional method. The laser light that can be used in the laser processing method is not particularly limited as long as it can perforate the film, but examples include CO2 laser, Nd:YAG laser, excimer laser, semiconductor-pumped solid-state laser, and pulse fiber laser.

[0056] In the case where the release film for semiconductor mold of the present invention has a through hole α, in a chart in which the release layer surfaces are rubbed against each other to measure the coefficient of dynamic friction, the vertical axis is the load and the horizontal axis is the displacement, the point at which the relative slippage between the contact surfaces starts is D0, and the point at which the contact surface moves 60 mm from D0 is D 60 , D0 and D 60 The maximum load between FD max (g) D0 and D 60 The minimum load between FD min (g), F.D. max (g) and FD min When the difference between the film thickness and the mold thickness is ΔFD(g), it is preferable that ΔFD(g) is 0.1 g or more and 200 g or less. By controlling the film thickness within this range, when the release film is placed on the silicon wafer and the mold, the release film has an appropriate air release property, and therefore the vacuum suction fixation of the silicon wafer is excellent.

[0057] The means for making ΔFD(g) 0.1 g or more and 200 g or less or the above-mentioned preferred range is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include a method for reducing burrs when forming through holes α. More specifically, when a punching method is used, a method for processing by sandwiching soft interleaf paper such as polyvinyl chloride between the needle and the film and on the needle's penetration surface side when forming through holes, a method for increasing the maximum diameter of through holes α within the range of the present invention, a method for reducing the number of through holes α to 0.3 / mm 2 Burrs can be reduced by using a laser processing method which is less likely to form burrs than a punching method, slowing down the needle insertion speed, and the like.

[0058] <Method of Manufacturing Semiconductor Chip Sealing Body> As a method for producing an encapsulated semiconductor body using the release film of the present invention, it is preferable to place the release film for semiconductor mold of the present invention on a mold having a suction hole on the lower side of a molding device as shown in FIG. 1. At this time, holes may be made in the release film by a carbon dioxide laser or the like, or holes may be made before placement. Thereafter, substrates such as silicon wafers on which semiconductor chips are arranged are stacked in order on the release film, a measured amount of molding resin is placed on the wafer, and then compression pressing is performed while heating the mold from above. At this time, the release film of the present invention may be placed between the molding resin and the upper mold. In the method for producing an encapsulated semiconductor body including at least the above steps, the release film for semiconductor mold is required to have easy drilling properties by a carbon dioxide laser, suppression of film protrusion at the guide pin portion, and suppression of mold contamination caused by the molding resin. In addition, in the face-up method, the release film is located on the lower side of the wafer, so it is conveniently positioned as the lower side, but in the face-down method, the semiconductor chip is located on the upper side, so the release film located between the wafer and the mold is the upper side when viewed from the line of sight. In other words, it means the midpoint between the opposite side of the silicon wafer that covers the semiconductor chips etc. with molding resin and the mold, and the semiconductor lower placement is the lower side from eye level in the face-up method and the upper side in the face-down method.

[0059] As described above, the release film for semiconductor mold of the present invention can suppress mold contamination caused by mold resin while suppressing the ease of drilling holes by a laser during compression molding and the film protrusion of guide pins. Therefore, the release film for semiconductor mold of the present invention is preferably used as a release film disposed between the mold of a semiconductor molding device and the lower part of a semiconductor. In addition, it can be suitably used in both face-down and face-up molding processes of the compression method. It can also be used as a release film for semiconductor mold in the transfer molding method.

[0060] [Methods for measuring and evaluating characteristics] (1) Polyester composition The polyester resin and film were dissolved in hexafluoroisopropanol (HFIP), 1 H-NMR and 13 The content of each monomer residue component and polyalkylene glycol is quantified using C-NMR. In the case of a laminated film, each layer of the film is scraped off according to the laminate thickness to collect and evaluate the components that make up each layer alone.

[0061] (2) Cross-sectional observation of release film The film is embedded in epoxy resin, and two cross sections, one in an arbitrary direction and the other in an orthogonal direction, are cut out perpendicular to the thickness direction using a known method (microtome method or ion milling method) appropriate for the type of particle. The cross sections are then observed using either a transmission electron microscope (TEM H7100, Hitachi) or a scanning electron microscope (SEM JSM-6700F, JEOL).

[0062] (2-1) Release film thickness, base film thickness, release layer thickness Using the above method, a magnification at which the release film thickness, base film thickness, and release layer thickness can be observed is selected, and images of three different points are obtained on cross sections in two directions, and the average value of a total of six points is calculated.

[0063] (3) Young’s modulus A rectangular sample with a length of 150 mm and a width of 10 mm is measured using an Instron-type tensile tester (Orientec Co., Ltd., automatic film strength and elongation measuring device "Tensilon" (registered trademark) AMF / RTA-100) according to the method specified in JIS Z1702 (1994). The measurement is performed under the following conditions, and 20 samples are measured. Sample size: width 10mm x length 50mm Pulling speed: 300mm / min Measurement environment: temperature 23℃, humidity 65%RH.

[0064] (4) Bending rigidity (3) The Young's modulus obtained by the evaluation is E (N / mm 2 ), the measurement width of the sample size is b (mm), and the thickness of the measurement sample is h (mm), and the value obtained from the following calculation formula (i) is the bending rigidity.

[0065] Bending stiffness (N mm 2 10 -3 )=(E×b×h 3 ) / 12···(i) (5) Piercing strength Measurements are performed under the following conditions in accordance with JIS-Z-1707 (2019) using a Shimadzu Corporation universal projector (Autograph AG-1S). The film is cut into a circle with a diameter of 15 mm to be used as the measurement sample. The average value of 10 measurements is the puncture strength [N].

[0066] Method: JIS Z1707(2019) Needle size: φ1.0mm, R0.5mm Sample size: φ20mm Piercing speed: 50mm / min Measurement environment: room temperature (23℃), humidity 65%RH.

[0067] (6) Hole drilling processability A carbon dioxide gas CO2 laser oscillator is used to scan the laser light using a galvanometer scanner to form through-holes α throughout the entire film so as to achieve the through-hole shape, processing pattern, maximum diameter (symbol 1), pitch (symbols 2 and 3), and aperture ratio shown in Figure 3 and below. Through hole shape: circular Processing pattern: Parallel Maximum diameter: 0.5mm Pitch 2: 2.0mm Pitch 3: 2.0mm Opening ratio: 5% The release film having through holes formed therein is evaluated as follows. A: No burrs are visible to the naked eye, and there are no burrs to grab hold of even when you run your finger over it. B: Slight burrs are visible and there are some catches from the burrs, but this does not cause any problems in practical use. C: Burrs are clearly visible to the naked eye, and the burrs cause strong adhesion, resulting in some problems with adhesion.

[0068] (7) Film protuberance Based on the tent diameter obtained by the method described in (8) Tent Diameter below, the pass / fail of the film protrusion during semiconductor molding is judged as follows, with A being the best. A: Tent diameter is less than 15 mm...There is little film bulge and the resin at the edges does not become thin after molding. B: Tent diameter is 15 mm or more and less than 30 mm...After molding, slight thinning of the resin at the edges occurs. C: Tent diameter 30 mm or more and less than 50 mm...Thinning of the resin at the edges occurs, but this does not cause any problems in practical use. D: Tent diameter 50 mm or more...The film bulges significantly, slightly affecting practicality.

[0069] (8) Tent diameter Using a vacuum forming machine 300X manufactured by Seiko Sangyo Co., Ltd. and an automatic mold temperature regulator KYM-3 manufactured by Kato Riki Seisakusho Co., Ltd., a sample was vacuum formed under the following conditions, and the circular shape of the film contacting the plate from the guide pin was marked with an oil-based pen, and the area of ​​the circular shape obtained from the marked shape was calculated using the method described below in (9) Circular Shape Area Analysis. The area of ​​the circular shape obtained was assumed to be the area of ​​a perfect circle, and the diameter of the circle was calculated from the area of ​​the circle, and the diameter of the circle was taken as the tent diameter. <Vacuum forming machine conditions> Mold: A plate measuring 80 mm wide x 180 mm long x 2 mm thick with a cylindrical guide pin measuring 3 mm in diameter and 4 mm in height fixed in the centre. Heater zone 1: 80℃ Heater zone 2: 80℃ Heater zone 3: 80℃ IR heater: 200℃ Heating time: 40 seconds Vacuum forming time: 1 minute <Mold temperature controller conditions> Pump pressure: 0.14~0.19MPa (9) Area analysis of a circular shape A circle with a diameter of 4 cm is marked with an oil-based pen in one place near the marking on the film that was marked with the oil-based pen. The marked film is photographed with a camera from a distance of 10 cm at a resolution of 1280 x 960 pixels and the image is captured. The captured image is opened in Media Cybernetics' ImagePro10 and the inside and outside of the two circles are binarized. The binarized data is used to analyze the ratio of the inside areas of the two circles. The area of ​​a 4 cm diameter circle is πr 2 =12.56cm 2 Therefore, multiply this by the ratio of the area of ​​the circle marked in (8) to the area marked with a diameter of 4 cm to calculate the circular area, where π = 3.14.

[0070] (10) 31B tape peel strength of the release layer after heating at 170°C The release film of the present invention is heat-treated for 10 minutes in a hot air oven heated to 170°C. Next, an acrylic polyester adhesive tape (Nitto Denko Corporation, Nitto 31B tape, 19 mm width) is attached to the release surface of the release film heat-treated at 170°C (if a release layer is present, the release layer), and a 2 kgf roller is moved back and forth once from above to prepare a tape-laminated film. After that, the tape-laminated film is left to stand for 24 hours in an environment of 25°C and 65% RH, and then the peel force (N / 19 mm) is measured at a peel angle of 180° and a tensile speed of 300 mm / min using an Instron type tensile tester (Orientec Co., Ltd., automatic film strength and elongation measuring device "Tensilon" (registered trademark) AMF / RTA-100). From the graph of peel force (N / 19 mm) versus test time (sec) obtained by the measurement, the average peel force at 5 to 10 seconds is calculated. The same measurement is carried out five times, and the average of the three measurements excluding the maximum and minimum values ​​is taken as the peel strength FA (N / 19 mm) of the laminated film.

[0071] (11) Thinning of the end resin after compression molding A compression molding device (Apic Yamada Co., Ltd.: device name "WCM-300") is used, and a mold having a cylindrical guide pin with a diameter of 3 mm and a height of 2 mm is used. A release film that will be the lower part of the semiconductor is placed on the mold so that the release layer is in contact with the silicon wafer to be placed thereafter. Next, a 12-inch silicon dummy wafer is placed on the release surface (or the release layer if there is one), and a mold resin (Nagase ChemteX Co., Ltd.: product name "R4507") measured with a dispenser is dropped onto the silicon wafer so that the dummy chip is covered with a thickness of 1 mm. Next, a release film is placed on a concave upper mold so that the release surface of the release film is in contact with the mold resin, and then the release film is fixed by vacuum suction so as not to cause wrinkles, and the lower mold is raised and vacuum molded to obtain a compression molded sample. The mold temperature is 125°C, the mold pressure is 4 MPa, and the cure time is 10 minutes.

[0072] Five molded samples are prepared using the above method, and the molded resin after the release film is peeled off is visually inspected for thinning of the end resin at the ends and evaluated according to the following criteria. A: No thinning of the resin at the ends was observed in any of the samples. B: Thinning of the resin at the edge is observed in one sample. C: Thinning of the resin at the edges is observed in two or more samples. D: Thinning of the resin at the edges was observed in two or more samples, and thinning of the resin at the edges was observed in two or more locations on one sample.

[0073] (12) Film tearing after compression molding (11) The film is processed according to the method described above, and after the release film is peeled off, the film is visually inspected and judged as follows: A: No visible tears in the film B: Film tears of 5 cm or less in length can be seen with the naked eye.

[0074] (13) Wrinkles in molded resin after compression molding (11) Processing is carried out according to the method described above, and the mold resin after the release film is peeled off is visually inspected and judged as follows. A: No visible wrinkles B: Wrinkles less than 3 cm long are visible to the naked eye, but are not a problem for practical use. C: Wrinkles of 3 cm or more in length are visible to the naked eye, but do not pose a problem in practical use.

[0075] (14) Thinning of end resin after transfer molding Using a transfer molding machine YPM1180 (TOWA Corporation), the release film of the present invention (or the release layer, if any) is placed on a lower mold having a cylindrical guide pin with a diameter of 3 mm and a height of 2 mm so that it is in contact with the epoxy substrate to be placed thereon. Next, a dummy epoxy substrate is set on the release film, and the release film is vacuum-sucked and fixed to the upper mold, and then the mold is clamped, and a sealant (HC-300B, manufactured by Nitto Denko Corporation) is transfer molded under the conditions of a mold temperature of 170°C, an injection pressure of 7.7 MPa, and a curing time of 5 minutes. After the release film is peeled off, the molded resin is visually observed for thinning of the end resin at the end, and evaluated according to the following criteria. A: No thinning of the resin at the ends was observed in any of the samples. B: Thinning of the resin at the edge is observed in one sample. C: Thinning of the resin at the edges is observed in two or more samples. D: Thinning of the resin at the edges was observed in two or more samples, and thinning of the resin at the edges was observed in two or more locations on one sample.

[0076] (15) Film tearing after transfer molding (14) The film is processed according to the method described above, and after the release film is peeled off, the film is visually inspected and judged as follows: A: No visible tears in the film B: A tear of less than 1 cm in size can be visually observed in the film. C: A tear in the film of 1 cm or more can be visually confirmed.

[0077] (16) Wrinkles in mold resin after transfer molding (14) Processing is carried out according to the method described above, and the mold resin after the release film is peeled off is visually inspected and judged as follows. A: No visible wrinkles B: Wrinkles less than 3 cm long are visible to the naked eye, but are not a problem for practical use. C: Wrinkles of 3 cm or more in length are visible to the naked eye, but do not pose a problem in practical use.

[0078] (17) Mold contamination After performing 100 shots of molding using the methods described in (11) and (14), the mold is visually inspected and judged as follows: A: In both cases, no visible mold contamination caused by the molding resin was observed. B: In both cases, mold contamination caused by the molding resin was visible in three or fewer places within a radius of 3 cm, but this does not pose a problem for practical use. C: In both cases, mold contamination caused by the molding resin was visible in four or more places within a radius of 3 cm, but this did not cause any problems in practical use. A is the best.

[0079] (18) Oxygen permeability According to the isobaric method of JIS K 7126-2 (2006), an oxygen transmission rate measuring device "OXTRAN" (registered trademark) manufactured by MOCON / Modern Controls is used to measure oxygen transmission rate under conditions of a temperature of 23°C and a humidity of 90% RH, with the film set to transmit oxygen from any side. Measurements are performed once on each side of two test pieces, and the average of the four measured values ​​is calculated to be the oxygen transmission rate of the sample (unit: cc / m 2 / day).

[0080] (19) Mold releasability After molding in (11) or (14), the release film is peeled off and the evaluation is performed as follows. A: The release film peels off from the mold resin, leaving no residue. B: The release film cannot be peeled off from the mold resin, or the release film is visibly attached to the mold resin.

[0081] (20) Crystal melting peak temperature Tm and crystal melting enthalpy of the resin constituting the base film Weigh out 5 mg of the sample using an electronic balance, place it in an aluminum sample pan, and measure it using a Rigaku Corporation Thermo plus ECO2 series DSC vesta, heating from 25°C to 300°C at 20°C / min in accordance with JIS K7121 (1987) and JIS K7122 (1987). Data analysis is performed using the same company's Thermo plus ECO2 system. The crystal melting peak temperature and crystal melting enthalpy of each peak are obtained from the obtained DSC data. When multiple crystal melting peaks are observed, they are named Tm1, Tm2, ​​... in order from the lowest peak temperature.

[0082] (21) The static friction coefficient μ when the release surfaces are rubbed together s , and the dynamic friction coefficient μ d First, two release film samples of the present invention are cut into rectangles measuring 80 mm in the width direction and 200 mm in the length direction, and the load when the release surfaces are rubbed against each other is measured in accordance with JIS-K7125 (1999) to obtain a chart as shown in Figure 4, and the static friction coefficient and dynamic friction coefficient are calculated from the load value on the chart. The obtained values ​​are the static friction coefficient μ s , the coefficient of dynamic friction μ when the release surfaces are rubbed against each other d The test machine used is a slip tester manufactured by Toyo Seiki Co., Ltd.

[0083] (22) Maximum load, FD max (g), F.D. min (g), ΔFD(g) From the chart obtained when measuring the friction coefficient by the method described in (21), FD max (g), F.D. minCalculate ΔFD(g) and ΔFD(g). The specific procedure is explained below with reference to Figure 4. In measuring the friction coefficient, the test machine is operated to pull one of the measurement samples, and the force increases linearly, causing friction and reaching a maximum load of 14. If the sample continues to be pulled further, the load will temporarily decrease, and then the load will begin to increase again as the relative slippage between the contacting surfaces begins. The point at which the load begins to increase is designated as point D015, the start of the relative slippage between the contacting surfaces. If the sample is then moved 60 mm in a straight line, the load will fluctuate during this time. At this point, the position 60 mm from D015 is designated as D 60 16, D015 to D 60 The maximum load between FD and 16 max 17. Minimum value FD min 18. F.D. max 17 and FD min The difference between 18 and ΔFD19. Note that FD max (g), F.D. min Both (g) and ΔFD(g) are the static friction coefficient μ when the release surfaces of (2) are rubbed against each other. s and the coefficient of dynamic friction μ d As with the above, the average value is taken from three measurements.

[0084] (23) Determination of biaxial alignment state by laser Raman spectroscopy The orientation parameters defined below are measured under the following conditions. MD and TD cross sections are cut out from the measurement sample, and the orientation parameters for each direction are calculated by measuring from the cross-sectional direction. Cross-sectional measurements are performed on the front, center, and back surfaces, and the orientation distribution in the thickness direction is also confirmed. For measurements from the front surface, the polarization angle is rotated in 15 degree steps to measure the angular distribution of the orientation degree on the MD and TD surfaces. Using the orientation parameters in the MD and TD directions obtained from the cross-sectional measurement, the obtained scattering intensity is converted to the orientation parameters for each direction. The orientation parameters are standardized for all directions and levels, and directly reflect the degree of orientation (not linear with respect to the degree of orientation). In the case of no orientation, the value is 1, and the higher the value, the more components are oriented in that direction. An orientation parameter of more than 2 is considered to be biaxially oriented. Equipment: T-64000 (Jobin Yvon / Atago Bussan) Conditions: Measurement mode; Raman microscopy Objective lens: x100 Beam diameter: 1 μm Light source; Ar + Laser / 514.5nm Laser power: 60 mW Diffraction grating; Single 1800gr / mm Slit: 100μm Detector: CCD / Jobin Yvon 1024×256 Intensity with polarization parallel to the MD or TD direction ((I 1615 ) parallel) and perpendicularly polarized light ((I 1615 The ratio of (vertical) to (axial) is used as a parameter for evaluating the degree of orientation. Orientation parameter R=I 1615 Parallel / I 1615 vertical I 1615 Parallel: 1615cm in a deflection arrangement parallel to the MD and TD directions -1 Raman band intensity I 1615 Vertical: 1615 cm in a deflection configuration perpendicular to the MD and TD directions -1 Raman band intensity (24) MOR The maximum and minimum values ​​of the transmitted microwave intensity are determined using a molecular orientation analyzer MOA-7015 manufactured by Oji Scientific Instruments, and the MOR value is calculated as the ratio of the maximum value to the minimum value (maximum value / minimum value). EXAMPLES

[0085] The present invention will be described below with reference to examples, but the present invention is not necessarily limited to these.

[0086] 1. Production of polyester The polyester resin used for forming the substrate film was prepared as follows.

[0087] (Polyester A) Polyethylene terephthalate resin (intrinsic viscosity 0.65) containing 100 mol % terephthalic acid as the dicarboxylic acid component and 100 mol % ethylene diol as the diol component.

[0088] (Polyester B) A copolymerized polyester in which 1,4-cyclohexanedimethanol was copolymerized at 33 mol% relative to the diol component was used as cyclohexanedimethanol-copolymerized polyethylene terephthalate (intrinsic viscosity: 0.75).

[0089] (Polyester C) Isophthalic acid copolymerized polyethylene terephthalate resin (intrinsic viscosity 0.7) in which the isophthalic acid component is copolymerized at 17.5 mol% with the dicarboxylic acid component.

[0090] (Polyester D) A masterbatch (intrinsic viscosity 0.62) containing 10% by mass of polyethylene glycol 1000 (molecular weight 1000) in polyester A.

[0091] (Particle Master A) A master batch (intrinsic viscosity 0.65) containing agglomerated silica particles (specific gravity 2.2) with a number average particle size of 3.2 μm in polyester A at a particle concentration of 6 mass%.

[0092] (Particle Master B) A master batch (intrinsic viscosity 0.60) containing zeolite particles (specific gravity 2.2) with a number average particle size of 2.5 μm in polyester A at a particle concentration of 30 mass%.

[0093] 2. Resins other than polyester (Polypropylene) PP Prime Polymer (Grade J105G) manufactured by Prime Polypro, melting point 160℃ (Polystyrene)PS Polystyrene resin (grade 685) made by PS Japan.

[0094] (Polymethylpentene) "TPX" (registered trademark) (DX820) manufactured by Mitsui Chemicals, Inc., melting point 230°C.

[0095] (Coating material B-1) Long-chain alkyl group-containing polyvinyl resin ("Peiroyl" (registered trademark) 1050, available from Lion Specialty Chemicals Co., Ltd.) was used in an amount of 10 parts by mass calculated as solid content; melamine-based crosslinking agent ("Sumimal" (registered trademark) M-55, available from Sumitomo Chemical Co., Ltd.) was used in an amount of 2.5 parts by mass calculated as solid content; p-toluenesulfonic acid ("TAYCACURE" (registered trademark) AC-700, available from Teica Corporation) was used in an amount of 1.5 parts by mass calculated as solid content; toluene was used in an amount of 200 parts by mass; and methyl ethyl ketone was used in an amount of 70 parts by mass.

[0096] (Coating material B-2) Long-chain alkyl group-containing compound a: 10 parts by mass of a long-chain alkyl group-containing polyvinyl resin ("Peiroil" (registered trademark) 1050 manufactured by Lion Specialty Chemicals Co., Ltd.) converted into solid content Crosslinking agent b: 2.5 parts by mass of a melamine-based crosslinking agent ("Yu-ban" (registered trademark) 28-60 manufactured by Mitsui Chemicals, Inc.) converted into solid content Acid catalyst c: p-toluenesulfonic acid ("TAYCACURE" AC-700 manufactured by Tayca Corporation) 1.3 parts by mass in terms of solid content Solvent: 400 parts by weight of toluene and 130 parts by weight of methyl ethyl ketone.

[0097] 4. Manufacturing of release films for semiconductor molds Example 1 The resins shown in Table 1 were fed to a single-screw extruder set at 230°C. The resins were then melted at an extrusion temperature of 230°C, and after removing foreign matter and stabilizing the extrusion rate using a filter and a gear pump, the resins were discharged from a T-die into a sheet-like form onto a drum (hard chrome-plated with a maximum height of 0.2 μm) whose temperature was controlled at 60°C, to obtain a non-oriented film. At that time, the distance between the lip of the T-die and the drum was set to 35 mm, and the resin was brought into close contact with the drum using an air knife to obtain a semiconductor mold release film with a thickness of 50 μm.

[0098] Example 2 A release film for a semiconductor mold was obtained in the same manner as in Example 1, except that the raw material composition and the thickness of the base film were as shown in Table 1 and the extrusion temperature was 260°C.

[0099] Example 3 A release film for a semiconductor mold was obtained in the same manner as in Example 1, except that the raw material composition and the thickness of the base film were as shown in Table 1 and the extrusion temperature was 240°C.

[0100] Example 4 The raw materials mixed to have the composition and layer structure shown in the table were fed to separate vented twin-screw extruders with an oxygen concentration of 0.2% by volume, and melted at a cylinder temperature of 270°C for the A1 layer extruder and a cylinder temperature of 280°C for the A2 layer extruder. The single pipe temperature after the A1 layer and A2 layer were merged was 270°C, the die temperature was 270°C, and the T-die die was extruded in a sheet form onto a cooling drum whose temperature was controlled at 25°C. At that time, electrostatic was applied using a wire electrode with a diameter of 0.1 mm, and the film was adhered to the cooling drum to obtain an unstretched sheet. Next, the film temperature was increased with a heating roll before stretching in the longitudinal direction, and the film was stretched 3.2 times in the longitudinal direction at a stretching temperature of 85°C, and immediately cooled with a metal roll whose temperature was controlled at 30°C.

[0101] The film was then stretched 3.7 times in the width direction using a tenter-type transverse stretching machine with a preheating temperature of 85°C and a stretching temperature of 95°C, and then heat-treated at constant length in an atmosphere of 225°C for 12 seconds. Thereafter, the film was relaxed 1% in the width direction at the same temperature, and then further relaxed 2% in the width direction at a temperature of 200°C to obtain a polyester film with a thickness of 35 μm.

[0102] Next, the film was cooled to room temperature, and then coating material B-1 was applied to one side by gravure coating. The coating was then transported to a 110°C oven to pre-dry, and then heated and dried in a 160°C oven to obtain a release film with a release layer thickness of 250 nm.

[0103] The properties of the release film obtained above and the evaluation results of the surface coated with the release layer as the surface in contact with the molding resin (R surface) are shown in the table below.

[0104] (Examples 5 to 12, Comparative Examples 1 and 2) The film composition and thickness are shown in Table 1. Coating material B-2 was applied to one side as a release layer by gravure coating, then the film was transported to a 120°C oven to pre-dry, and then heated and dried in a 120°C oven to obtain a release film with a release layer thickness of 250 nm. The procedure was the same as in Example 4, except that a release film was obtained.

[0105] As shown in the table, the evaluation results of each property are inferior in Comparative Examples 1 and 2 in terms of film protuberance, hole drilling processability, and thinning of the end resin after molding.

[0106] [Table 1]

[0107] [Table 2]

[0108] [Table 3]

[0109] [Table 4]

[0110] [Table 5]

[0111] [Table 6]

[0112] [Table 7]

[0113] [Table 8] [Industrial Applicability]

[0114] The release film of the present invention can suppress the thinning of the end resin after molding caused by the film protuberance due to the guide pin during compression molding, and can provide a release film with excellent hole-drilling processability. Furthermore, such a release film can be suitably used as a release film for semiconductor molding in the semiconductor sealing process, thereby improving the mass productivity of semiconductor chips. [Explanation of symbols]

[0115] 1. Mold 2 Guide pins 3 Tent diameter 4 Suction hole 5 Lower release film 6 Silicon Wafer 7 Molding resin 8 Upper release film 9. Circular shape of the guide pin in contact with the plate 10 Release film 11 Maximum diameter 1 12 Pitch 2 13 Pitch 3 14 Maximum load 15 D0 16 D 60 17 FD max 18FD min 19 ΔFD

Claims

1. Bending stiffness is 10 x 10 －３ (N mm ２ ) or more 150 x 10 －３ (N mm ２ ) or less.

2. Oxygen permeability is 1 (cc / m ２ / day) or more 1000 (cc / m ２ 2. The release film for a semiconductor mold according to claim 1, wherein the release film has a viscosity of 1000:1 or less.

3. 3. The release film for a semiconductor mold according to claim 1, which comprises at least a release layer and a base film laminated in this order.

4. The release film for a semiconductor mold according to claim 3 , wherein the base film is mainly composed of a polyester resin.

5. 5. The release film for a semiconductor mold according to claim 4, wherein the polyester resin contains 0.5 mol % or more and 20 mol % or less of a cyclohexanedimethanol residue, a 1,4-butanediol residue, or a 1,3-propanediol residue in a diol component.

6. 6. The release film for a semiconductor mold according to claim 4, wherein the base film contains 0.1% by mass or more and 3.0% by mass or less of polyalkylene glycol.

7. 7. The release film for a semiconductor mold according to claim 6, wherein the polyalkylene glycol is polyethylene glycol.

8. 6. The release film for a semiconductor mold according to claim 4, wherein the polyester resin contains 0.5 mol % or more and 20 mol % or less of an isophthalic acid residue in a dicarboxylic acid component.

9. 5. The release film for a semiconductor mold according to claim 3, wherein the release layer is a thermosetting long-chain alkyl-based composition.

10. 5. The release film for a semiconductor mold according to claim 3, wherein the release layer has a 31B tape peel strength of 1.0 N / mm or less after heating at 170°C.

11. 4. The release film for a semiconductor mold according to claim 1, having a piercing strength of 2 N or more and 6 N or less.

12. 4. The release film for a semiconductor mold according to claim 1, wherein the Young's modulus in both the longitudinal direction and the width direction is 1.5 GPa or more and 3.0 GPa or less.

13. 4. The release film for a semiconductor mold according to claim 1, having through holes α, where a through hole having a maximum diameter of more than 0.1 mm and not more than 20.0 mm is defined as a through hole α.

14. In the chart where the release layer surfaces of the semiconductor mold release film are rubbed against each other to measure the coefficient of dynamic friction, the vertical axis is the load and the horizontal axis is the displacement, and the point where the relative slippage between the contact surfaces begins is D. ０ , D ０ The point 60 mm away from D ６０ , D ０ and D. ６０ The maximum load between FD ｍａｘ (g), D ０ and D. ６０ The minimum load between FD ｍｉｎ (g), F.D. ｍａｘ (g) and F.D. ｍｉｎ 14. The release film for a semiconductor mold according to claim 13, wherein ΔFD(g) is 0.1 g or more and 200 g or less, when the difference between ΔFD(g) and ΔFD(g) is 0.1 g or more and 200 g or less.

15. 4. The release film for semiconductor molding according to claim 1, wherein the molding method is a compression method.

16. The release film for a semiconductor mold according to claim 1 or 15, which is disposed between a mold of a semiconductor molding device and a lower portion of a semiconductor.

Images