JPWO2017130952A1 - Method of manufacturing semiconductor package and release film for manufacturing process of semiconductor package - Google Patents

Abstract

It is a manufacturing method of a semiconductor package. In the mold 11 in which the element 25 to be packaged is installed, the release film 21 is disposed on the cavity 14 surface to be filled with the thermosetting resin 27 for package production, and then the thermosetting resin 27 is placed in the mold 11. Fill. At this time, as the release film 21, a laminated film in which a base film disposed on the cavity 14 surface side and a peeling resin disposed on the thermosetting resin side are laminated is used. As a base film, a stretched polyester film having a melting point at two or more points above a mold set temperature is used.

Description

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

  In the field of semiconductor package manufacturing, a semiconductor element (chip) is sealed with a resin (mold resin) in order to protect and shield it from external environments such as contaminants, ambient air, impact, light, magnetism, high frequency and the like. As the mold resin, for example, a curable resin such as epoxy is generally used. When sealing is performed, although the contraction of the mold is shallow compared to other fields, the inside of the mold has a high temperature and high pressure environment.

  The semiconductor sealing process generally includes a transfer molding process, a compression molding process, and the like.

  The process will be described by taking the transfer molding process as an example. A semiconductor element incorporating a wired integrated circuit is placed on a mold, another mold is set from above, and high pressure is tightened, and then an epoxy resin The resin is cured, the mold is opened, the molded product is taken out, and the inner surface of the mold is cleaned. The sealing process is completed in the cleaning process.

  The inner surface of the mold is cleaned by repeated sealing and molding at a high temperature in the semiconductor sealing process, which causes the mold to be contaminated by the curable resin, thereby reducing the moldability or causing product quality This is because a reduction in yield occurs due to the reduction.

  On the other hand, in order to omit the cleaning process, the release film is disposed on the cavity surface of the mold. That is, when the semiconductor package is resin-molded by the mold, a release film is used to prevent the inner surface of the mold from being contaminated. The release film is disposed along the inner surface of the mold to prevent direct contact of the resin for forming the package, such as by solidification, with the inner surface of the mold. In the process using the release film, a film roll is loaded into the apparatus by, for example, a roll-to-roll method. The release film for that purpose does not generate wrinkles etc. when the stretched film is vacuumed and absorbed by the device mold, and has the ability to follow the mold, and the temperature of about 170 ° C. around the mold It is required to have specific mechanical characteristics such as heat resistance that can not shrink, sag or crease in a high temperature atmosphere, and releasability from the injected and cured epoxy resin.

  Patent Document 1 describes, as a release film of this type, a release film in which a fluorine resin is laminated on a stretched polyester resin film.

  Patent Document 2 describes a sheet in which an inorganic substance is vapor-deposited on one side of a stretched polyester resin film, and a release layer is provided on the other side.

  Patent Document 3 describes a film in which a copolyester film is provided with a release layer and a coating layer containing particles.

JP2006-49850A JP2004-79566A WO 2012/077571

  However, the fluorine resin laminate film disclosed in Patent Document 1 is expensive and easily corrodes the extruder screw at the time of production, hardly burns in incineration disposal after use, and is present at the time of incineration disposal. It is not preferable in terms of environmental pollution such as generation of poison gas.

  In recent years, the miniaturization and complexity of semiconductors have been advanced, and in accordance therewith, the required performance required for a release film for a semiconductor mold has been increased. That is, there is a demand for a mold release film for a semiconductor mold that can follow a small-sized and complex-shaped mold. From this point of view, the mold release film disclosed in Patent Documents 2 and 3 may not be able to follow a mold having a complicated shape. Furthermore, since the multi-layer release sheet has different trackability to each other, there is a concern that as the number of layers increases, the track difference between layers occurs, which causes wrinkles and the like.

  In the release film provided with the coating layer containing particles as shown in Patent Document 3, when the repeated molding is performed, the mold layer stains remarkably due to the falling off of the coating layer component and the contained particles. Due to this, for example, the film may be wrinkled to damage the appearance of the semiconductor package. Furthermore, there are many resin components and copolymerization components whose melting point is lower than the mold temperature, and low crystallinity resin components may be contained even if there is no melting point peak, and in those cases, a high temperature mold As a result, the film tends to stick and the releasability from the mold is greatly reduced, which may cause wrinkles and tears.

  Therefore, the present invention can follow molds of complicated shapes, can suppress wrinkles and the like, there are no troubles in manufacturing, is excellent in releasability, and is inexpensive and easy to dispose after use. In addition, it is an object of the present invention to make it possible to manufacture a semiconductor package using a release film free from environmental pollution.

  The inventors of the present invention have found that a mold temperature commonly used in the manufacture of semiconductor packages is 170 ° C., and a film having two or more melting points (Tm) higher than the mold temperature brings about appropriate characteristics in the semiconductor encapsulation process. The present invention has been achieved.

  That is, the gist of the present invention is as follows.

(1) A method of manufacturing a semiconductor package
When a mold release film is disposed on a cavity surface filled with a thermosetting resin for package production in a mold in which a device to be packaged is installed, and then the thermosetting resin is filled in the mold,
As the release film, a laminated film in which a base film disposed on the cavity surface side and a peeling resin disposed on the thermosetting resin side are laminated,
A method for producing a semiconductor package, comprising using a stretched polyester film having a melting point at two or more points above a mold set temperature as the base film.

  (2) A semiconductor package according to (1), characterized in that the polyester resin constituting the substrate film comprises a dicarboxylic acid component and / or a diol component containing an alkyl chain having 2 to 5 carbon atoms as a repeating component. Production method.

  (3) The method for producing a semiconductor package according to (1) or (2), wherein a polyester resin containing 20 to 60% by mass of polyethylene terephthalate is used as the polyester resin constituting the substrate film.

  (4) The method for producing a semiconductor package according to any one of (1) to (3), characterized in that a polyester resin containing 40 to 80 mass percent of polybutylene terephthalate is used as the polyester resin constituting the substrate film. .

  (5) The method for producing a semiconductor package according to any one of (1) to (4), wherein a release film having a thickness of 20 μm to 100 μm is used.

(6) After holding for 20 minutes at 5 kg / cm ² with a press set at 170 ° C., use a release film having a peeling strength of 1.0 N / cm or less with respect to an epoxy prepreg which has been cooled to room temperature and cured. The manufacturing method of the semiconductor package in any one of (1) to (5) characterized by these.

(7) In the mold in which the element to be packaged is installed, the mold release film is disposed on the cavity surface to be filled with the thermosetting resin for package production, and then the mold is filled with the thermosetting resin The mold release film used in a method of manufacturing a semiconductor package,
In the release film, a base film disposed on the cavity surface side and a release resin disposed on the thermosetting resin side are laminated,
The release film for the manufacturing process of a semiconductor package, wherein the base film is formed of a stretched polyester film having a melting point at two or more points at a mold set temperature or more.

  (8) The process for producing a semiconductor package according to (7), wherein the dicarboxylic acid component and / or the diol component of the polyester resin constituting the substrate film comprises an alkyl chain having 2 to 5 carbon atoms as a repeating component. Release film.

  (9) A release film for a manufacturing process of a semiconductor package according to (7) or (8), wherein the polyester resin constituting the base film contains 20 to 60 mass percent of polyethylene terephthalate.

  (10) The process for producing a semiconductor package according to any one of (7) to (9), wherein the polyester resin constituting the substrate film contains 40 to 80 mass percent of polybutylene terephthalate. Release film.

  (11) A release film for a manufacturing process of a semiconductor package according to any one of (7) to (10), which has a thickness of 20 μm to 100 μm.

(12) After holding at 5 kg / cm ² for 20 minutes with a press set at 170 ° C., it is characterized in that the peel strength from the epoxy prepreg cured and cooled to room temperature is 1.0 N / cm or less The mold release film for the manufacturing process of the semiconductor package in any one of (7) to (11).

(13) A release film in which a base film disposed on the cavity surface side of a molding die and a release resin disposed on the molding resin side are laminated,
A release film characterized in that the base film is a stretched polyester film having a melting point at two or more points above a mold set temperature.

  (14) The release film of (13), wherein the dicarboxylic acid component and / or the diol component of the polyester resin constituting the substrate film comprises an alkyl chain having 2 to 5 carbon atoms as a repeating component.

  (15) The release film of (13) or (14), wherein the polyester resin constituting the substrate film contains 20 to 60 mass percent of polyethylene terephthalate.

  (16) The release film according to any one of (13) to (15), wherein the polyester resin constituting the substrate film contains 40 to 80 mass percent of polybutylene terephthalate.

  (17) The release film of any of (13) to (16), which has a thickness of 20 μm to 100 μm.

(18) After holding at 5 kg / cm ² for 20 minutes with a press set at 170 ° C., it is characterized in that the peel strength from the epoxy prepreg cured and cooled to room temperature is 1.0 N / cm or less (13 The release film in any one of to (17).

  According to the method for manufacturing a semiconductor package of the present invention, the release film used is free from wrinkles, tears, etc. when vacuuming in a mold cavity under a high temperature atmosphere which is a mold setting temperature in the manufacture of a semiconductor package Since the mold can be followed and the releasability from the thermosetting resin and the mold is not broken well, a semiconductor package having a good appearance can be obtained. That is, there is an advantage that productivity is good in the process of continuous production.

  Further, since the release film of the present invention is composed of a polyester-based stretched film base having a specific structure and a release layer, it is excellent in mechanical strength, heat resistance, conformity and economy, and in particular, is a semiconductor. It is suitable as a mold release film for in-mold molding used for manufacture of a package etc.

It is a figure which shows the manufacturing method of the semiconductor package of embodiment of this invention. It is sectional drawing along the I-I line of FIG. It is a figure which shows the next process of FIG. 1 and FIG. It is sectional drawing along the III-III line of FIG. It is a figure which shows the next process of FIG. 3 and FIG. It is a figure which shows the process of FIG. 5 following. It is a figure which shows the next process of FIG. It is sectional drawing along the VII-VII line of FIG. It is a figure which shows the cross-sectional form of the release film based on this invention.

  First, a method of manufacturing a semiconductor package according to the embodiment of the present invention will be described.

  In FIG. 1 and FIG. 2, 11 is a mold for transfer molding of the semiconductor package, and the fixed upper mold 12 and the movable lower mold 13 which can be moved closer to or away from the upper mold 12 And have. The upper mold 12 is formed with a cavity 14 for embedding the thermoplastic resin constituting the semiconductor package. The cavity 14 includes a package forming portion 15, a resin introducing portion 16, and a gate 17 for connecting the package forming portion 15 and the resin introducing portion 16 to each other. The lower die 13 is formed with a resin feed passage 18 for feeding the thermosetting resin in a molten state to the resin introduction portion 16.

  A release film 21 according to the present invention is loaded between the upper mold 12 and the lower mold 13 in a roll-to-roll manner. 22 is a delivery roll, and 23 is a winding roll.

  The package forming portion 15 of the cavity 14 is provided in a pair in the width direction of the release film 21 as shown in FIG. 1, and a plurality is provided in the length direction of the release film 21 as shown in FIG. . The resin introducing portion 16 is provided between the package forming portions 15 corresponding to the pair of package forming portions 15 in the width direction of the release film 21. Further, although not shown in the drawings, one resin introducing portion 16 is provided for each of the pair of package forming portions 15 different in position along the length direction of the release film 21.

  When manufacturing the semiconductor package, as shown in FIGS. 1 and 2, the lower mold 13 is moved away from the upper mold 12 to open the mold, and the take-up roll 23 is rotated to be supplied from the delivery roll 22. An unused new portion of the release film 21 is fed between the upper mold 12 and the lower mold 13 with tension applied to this portion.

  Thereafter, as shown in FIGS. 3 and 4, the portion of the release film 21 present between the upper mold 12 and the lower mold 13 is attached to the inner surface of the cavity 14 by vacuum suction. At this time, the release film 21 according to the present invention has the advantage that it satisfactorily follows the inner surface shape of the cavity 14 as described later, and moreover, there is no occurrence of "wrinkling" etc. when sticking to the inner surface of the cavity 14. is there. When "wrinkles" occur, in molding, the wrinkles are transferred to the molded product to cause appearance defects.

  Thereafter, as shown in FIG. 5, the semiconductor substrate 26 on which the semiconductor element 25 is mounted is placed on the copper plate 24 at a position corresponding to the package forming portion 15 of the cavity 14 in the lower mold 13. The copper plates 24 are separated from each other in the width direction of the release film 21 corresponding to the pair of package forming portions 15, 15, and in the longitudinal direction of the release film 21 corresponding to the plurality of package forming portions 15, 15. Are continuous with one another.

  Then, as shown in FIG. 6, the lower mold 13 is moved in the direction approaching the upper mold 12 to perform mold clamping, and from the resin feed path 18 of the lower mold 13 to the resin introducing portion 16 of the cavity 14 shown in FIG. The thermosetting resin 27 such as epoxy resin is pressure fed in a molten state. The thermosetting resin 27 fed to the resin introducing portion 16 is filled in the package forming portion 15 through the gate 17. Thus, the semiconductor element 25 and the semiconductor substrate 26 are embedded inside the thermosetting resin 27. The surface of the copper plate 24 opposite to the side on which the semiconductor element 25 and the semiconductor substrate 26 are embedded is exposed from the thermosetting resin 27. In detail, as shown in the drawing, a plunger 19 is disposed inside the resin feed path 18, and the thermosetting resin 27 is compactly filled into the inside of the cavity 14 by the plunger 19.

  At this time, when using the above-mentioned epoxy resin generally used for a semiconductor package as the thermoplastic resin 27, the temperature of the mold 11 is set to 170 ° C. or higher, preferably 170 ° C. to 180 ° C. Preferably, the temperature is set to 170 ° C to 175 ° C. At such a high temperature, the release film 21 according to the present invention has heat resistance as described later, so that it has the feature that heat shrinkage and "wrinkling" caused by it do not occur.

  When the filled resin 27 is cured, the lower mold 13 is moved away from the upper mold 12 to open the mold as shown in FIGS. 7 and 8, and the resulting molded product 28 is taken out of the mold 11. At this time, as described later, the mold release film 21 based on the present invention has a good mold release property from the thermosetting resin 27 such as an epoxy resin. Thereafter, the take-up roll 23 is driven to discharge the used portion of the release film 21 from the mold 11, and, as shown in FIGS. 1 and 2, an unused portion of the release film 21 is newly renewed. Introduce to mold 11

  In the above, the “transfer molding process” has been described in which the thermosetting resin 27 in a molten state is consolidated and filled into the mold 11 from the outside. However, the mold release film 21 is similarly used in other molding processes, for example, a known "compression molding process" in which a mold is filled with a thermosetting resin in powder form and then clamping is performed. be able to.

  Hereinafter, the release film 21 based on this invention is demonstrated in detail.

  As shown in FIG. 9, the mold release film 21 is good from the base film 31 disposed on the cavity 14 side of the mold 11 shown in FIGS. 1 to 8 and the thermosetting resin 27 after curing. It is comprised by the laminated body provided with the resin layer 32 for peeling arrange | positioned at the same resin 27 side in order to peel.

  First, the base film 31 will be described in detail. The base film 31 is formed of a stretched polyester film having two or more melting points at, for example, 170 ° C. or more, which is equal to or higher than a mold set temperature.

  Having two or more melting points above the mold set temperature means that two or more types of polyester resins each having a melting point equal to or more than the mold set temperature are blended. By blending two or more types of polyester resins, each of which has a melting point equal to or higher than the mold setting temperature, flexibility at a high temperature of 170 ° C., which is the mold temperature of the resin on the low melting side, follows the mold. There is an advantage that the heat resistance of the resin on the high melting side is improved to prevent breakage at the time of mold release.

  Examples of such polyester resins include polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate. Furthermore, those copolymers etc. can be mentioned.

  Among them, those in which the dicarboxylic acid component and / or the diol component constituting the polyester contains an alkyl chain having 2 to 5 carbon atoms as a repeating component are easily moved by the polymer chain at high temperature, and followability to the mold Particularly preferred to be optimal. Examples of such polyester resins include those having a melting point of 170 ° C. or more, such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and copolymers such as adipic acid copolymer polyester.

  The polyester film which comprises a base film needs to be a stretched film. The reason is that the unstretched film is not oriented, so the strength is low, so it is broken at the time of molding, and shrinkage is large and wrinkles occur in a high temperature atmosphere such as a mold.

  Although it does not specifically limit as a polymerization method of the polyester resin of a raw material, For example, well-known manufacturing methods, such as a direct esterification method and a transesterification method, are mentioned. As a direct esterification method, for example, a method in which a necessary monomer raw material is injected into a reaction vessel, an esterification reaction is performed, and then a polycondensation reaction is performed. In the esterification reaction, the mixture is heated and melted for reaction for 4 hours or more at a temperature of 160 ° C. or more under a nitrogen atmosphere. At that time, oxides such as magnesium, manganese, zinc, calcium, lithium, titanium and acetate may be used as a catalyst. In the polycondensation reaction, the reaction is allowed to proceed to a desired molecular weight at a temperature of 220 to 280 ° C. under reduced pressure of 130 Pa or less. At that time, oxides such as antimony, titanium, germanium and the like may be used as catalysts.

  Since the polyester resin after polymerization contains monomers, oligomers, and byproducts such as acetaldehyde and tetrahydrofuran, solid phase polymerization may be performed at a temperature of 200 ° C. or higher under reduced pressure or inert gas flow. The use of polyester subjected to solid phase polymerization is preferable because precipitation of oligomers on the surface of the unstretched sheet and film extruded in the manufacturing process of the base film 31 is prevented. With regard to the oligomer, it is preferable that the contamination to the mold and the like be less in a precise process such as semiconductor sealing. For this reason, the above-mentioned solid phase polymerized one is preferable.

  When polymerizing the polyester resin, if necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, an antistatic agent, an antiblocking agent, etc. may be added. As an antioxidant, a hindered phenol type compound and a hindered amine type compound are mentioned, for example. As a heat stabilizer, a phosphorus compound is mentioned, for example. As a ultraviolet absorber, a benzophenone series compound and a benzotriazole type compound are mentioned, for example. Examples of the antistatic agent include antimony-doped tin oxide. As an antiblocking agent, a silicon oxide is mentioned, for example.

  The polyester resin used for this invention can copolymerize another component suitably in the range which the effect of this invention is not impaired. The acid component used for the copolymerization is not particularly limited, and is, for example, isophthalic acid, (anhydride) phthalic acid, 2,6-naphthalenedicarboxylic acid, aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, oxalic acid, succinic acid Aliphatic acid such as adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid (anhydride), maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, etc. (anhydride) hexahydrophthalic acid, hexahydroterephthalic acid And the like. Alicyclic dicarboxylic acids such as C 20-60 dimer acids, p-hydroxybenzoic acid, lactic acid, 4-hydroxybutyric acid, hydroxycarboxylic acids such as ε-caprolactone, (anhydride) trimellitic acid, trimesic acid ( Anhydride) Polyfunctional carboxylic acids, such as pyromellitic acid, etc. can be mentioned. These copolymerization components may be used in combination of two or more.

  The alcohol component used for the copolymerization is not particularly limited, and diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1 Aliphatic diols such as 1,6-hexanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexanediethanol, bisphenol A and the like Aromatic diols such as ethylene oxide or propylene oxide adducts of bisphenol S, and polyfunctional alcohols such as trimethylolpropane, glycerin and pentaerythritol can be mentioned. These copolymerization components may be used in combination of two or more.

  The proportion of the copolymerization component is preferably at most 20 mol%, more preferably at most 15 mol%. If it exceeds 20% by mole, the crystallinity of the resin is reduced, which lowers the strength at the time of film formation, and as a result, breakage tends to occur at the time of mold release. Moreover, since melting | fusing point falls, so that a copolymerization amount increases, it is unpreferable in the heat resistant surface.

  As described above, the base film is formed of a polyester film obtained by blending two or more types of polyester resins each having a melting point above the mold set temperature.

  When polyethylene terephthalate is used as the blend ratio of the polyester resin, the blend ratio is preferably 20 to 60 mass percent, the more preferable lower limit is 25 mass percent, and the upper limit is 55 mass percent. Moreover, when using a polybutylene terephthalate, it is preferable that the blend ratio is 40 to 80 mass percent, A more preferable lower limit is 45 mass percent, and an upper limit is 75 mass percent.

  When polyethylene terephthalate is used, the film is less likely to be broken due to the heat resistance of the polyethylene terephthalate when molding at high temperature. Polybutylene terephthalate, for example, has two aliphatic carbon atoms contained in the chemical skeleton more than polyethylene terephthalate, so the mobility of the molecular chain is high and the flexibility is high. For this reason, by mixing two or more types of resins having different skeletons of polyethylene terephthalate and polybutylene terephthalate as two of the two or more types of resins constituting the base film 31 in the above-described optimal ratio. The flexibility of the obtained film is improved, and the mold followability at the time of molding is improved.

  When the content of polybutylene terephthalate is more than 80% by mass, the properties are excessively developed to lower the mechanical strength and the heat resistance. Therefore, wrinkles are easily generated at the temperature at the time of molding, and the tear is easily generated at the time of mold release. On the other hand, when the content of polyethylene terephthalate exceeds 60% by mass, the characteristics are excessively expressed to deteriorate the mold following property and also to be hard and easily cracked. Therefore, even if it has mechanical strength, it is easily broken at the time of mold release Become.

  The manufacturing method of the base film 31 is not particularly limited, and conventionally known methods can be used. For example, a resin sheet extruded by a known method such as a T-die method or a tubular film forming method is used as an unstretched sheet, and then this unstretched sheet is uniaxially stretched, simultaneous biaxial stretching, sequential biaxial stretching Stretching is performed by a known method such as a method. The base film 31 needs to be a stretched film, and thus a stretching step is required. The unstretched sheet has low crystallinity and is poor in heat resistance. In order to produce a film with less thickness unevenness, it is preferable to obtain a resin sheet by T-die method, and then it is stretched by sequential biaxial stretching or simultaneous biaxial stretching.

  As a detailed manufacturing method of the base film 31, for example, a resin composition having polyethylene terephthalate and polybutylene terephthalate in the above ratio is melted at 230 to 280 ° C. using an extruder equipped with a T-die, and then the T-die is produced. It is preferable to extrude it into a sheet-like shape, adhere it to a casting roll adjusted to a temperature of 40 ° C. or lower, and quench it to obtain an unstretched sheet of a predetermined thickness. In order to uniformly mix the raw resin composition, a material previously melt-blended may be used.

  When the unstretched sheet obtained as described above is stretched by, for example, a flat simultaneous biaxial stretching method, both ends in the width direction of the unstretched sheet are gripped with clips, and 40 to 100 ° C. from both sides of the sheet. Hot air is blown to preheat, and the film is stretched by about 2 to 4 times in the longitudinal direction and the transverse direction under an atmosphere of 50 to 120 ° C. Thereafter, it is treated at about 80 to 180 ° C. for several seconds to relax several% in the longitudinal or transverse direction. Further, in order to obtain a film having a predetermined shrinkage rate, the film is heat-set at 80 to 200 ° C. for several seconds for heat setting, then cooled to room temperature and taken up at a speed of 20 to 300 m / min. If the stretching temperature is less than 50 ° C., necking tends to occur because the stretching stress is too high. On the other hand, if the stretching temperature exceeds 120 ° C., the film may melt and the film may be crystallized too much to cause whitening. When the heat setting temperature exceeds 200 ° C., the film tends to sag and the quality of the film is significantly impaired.

  A publicly known method can be adopted as a heat setting method after drawing. For example, a method of blowing hot air to the stretched film, a method of irradiating the stretched film with infrared rays, and a method of irradiating the stretched film with microwaves can be mentioned. The method of blowing hot air to the stretched film is preferable in that it can be uniformly and accurately heated. A heat buffer process may be provided between the drawing process and the heat setting process.

  The layer configuration of the base film 31 is not particularly limited, and may be any layer configuration such as a single layer, two types, two layers, two types, three layers, three types, three layers, and the like. Among them, a multilayer capable of controlling the surface roughness for each side is preferable. Moreover, it is preferable that polyester is 90 mass% or more of the whole of the base film 31. If it is less than that, the flexibility specific to polyester is insufficient, and the followability in molding tends to be inferior.

  In order to improve the winding property of the release film 21, the base film 31 may contain particles. The particles are not particularly limited insofar as the effect of the present invention is not impaired as long as the particles can be lubricated. Specific examples thereof include inorganic particles of silica, alumina, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, titanium oxide, barium sulfate and the like.

  Alternatively, heat-resistant polymer particles made of silicone resin, crosslinked polystyrene resin, etc., organic lubricant such as fatty acid ester or fatty acid amide, thermosetting urea resin, thermosetting phenol resin, thermosetting epoxy resin, benzoguanamine resin, etc. The heat-resistant organic particles of Furthermore, it is also possible to use precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed in the polyester production process. The shape of the particles to be used is not particularly limited, and may be spherical, massive, rod-like, flat or the like. The hardness, specific gravity, color and the like are not particularly limited. These particles may be used in combination of two or more as needed.

  The average particle size of the particles is usually in the range of 0.01 to 6 μm, preferably 0.01 to 1 μm. When the average particle size is less than 0.01 μm, the particles may be easily aggregated and the dispersibility may be insufficient. On the other hand, when the average particle size exceeds 6 μm, the surface of the film becomes too rough, and problems may occur when the resin layer 32 for peeling shown in FIG. 9 is applied in a later step.

  The method for causing the base film 31 to contain the particles is not particularly limited, and the particles can be added at any stage of producing the polyester. For example, an esterification step or a transesterification end step.

  Considering that the surface state of the release film 21 is transferred to the thermosetting resin in the semiconductor sealing step, for example, kneading the above-mentioned particles into the release film 21 for the purpose of imparting the design property thereof It is also possible to carry out emboss processing and sand mat processing in an off-line process, and cooling and molding using a satin roll in an in-line process.

  Furthermore, the release film 21 can contain a coloring agent, an antioxidant, an antifoaming agent, an antistatic agent, an ultraviolet light absorber, and the like.

  The thickness of the release film 21 is preferably 20 to 100 μm, more preferably 20 to 80 μm, still more preferably 25 to 60 μm, and most preferably 35 to 60 μm. If the thickness of the release film 21 is less than 20 μm, the breaking strength is low, which is likely to cause breakage during release, and when the thickness is more than 100 μm, the followability tends to decrease. However, since the base film 31 is a stretched film, in addition to the heat resistance and the strength is high, it is a thin film as compared with the 50 μm thick film which is mainly used as a release film for a semiconductor package manufacturing process. Can be expected. In addition to cost merits, thinning of the film can increase the length of the film constituting the roll 22 shown in FIGS. 2, 4 and 8, thereby reducing the loading frequency of the roll in the semiconductor sealing process. It is possible to greatly contribute to the improvement of workability.

  The peeling resin layer 32 shown in FIG. 9 will be described. The composition of the release resin layer 32 is not particularly limited, and known release agents such as thermosetting or radiation-curable silicones, fluorines, long-chain alkyls, non-silicones such as polyolefins, etc. Layers can be mentioned. Examples of the thermosetting silicone include addition reaction silicones and condensation reaction silicones. Examples of radiation curable silicones include UV curable silicones and EB curable silicones. Further, fluorine-based resins include those converted into fluorine resin films and coating solutions of fluorine-based materials, long-chain alkyl-based solvents include coating solutions of long-chain alkyl group-containing polymers, and polyolefin-based resins include polyethylene resins and polypropylene resins And polyolefin-based resins such as polymethylpentene as films, and coating solutions of acid-modified polyolefin resins.

The release film 21 in the present invention is held at 5 kg / cm ² for 20 minutes with a press set at 170 ° C. and then cooled to room temperature and has a peel strength of 1.0 N / cm or less with respect to the cured epoxy prepreg. Is preferably 0.7 N / cm or less, more preferably 0.5 N / cm or less, and most preferably 0.3 N / cm or less. The release resin layer 32 is not particularly limited as long as the release strength is satisfied, and it is a release resin layer formed by applying a coating solution from the viewpoint of thinning the release film 21. preferable. It is sufficient if the peeling resin layer 32 is thinly formed on the surface of the base film 31. As the formation method, an in-line coating method and an off-line coating method can be mentioned. The in-line coating method is desirable in terms of cost advantages.

  The measuring method of the characteristic value in a following example and a comparative example is as follows.

(1) Melting point (° C)
The melting point of the substrate film was measured using a Perkin Elmer DSC by raising the temperature at 20 ° C./min.

(2) Thickness The thickness was measured using a thickness measuring instrument MT-12B manufactured by HEIDENHAIN.

(3) Peeling strength: Both sides of an epoxy prepreg (EI-6765 manufactured by Sumitomo Bakelite Co., Ltd.) with a size of 60 mm × 100 mm are sandwiched between mold release films, and 5 kg with a press machine set at 170 ° C. as a mold setting temperature. It held at / cm ² for 20 minutes. Thereafter, it was cooled to room temperature to obtain a sample. The peel strength between the cured epoxy prepreg and the release film of the obtained sample was measured in a constant temperature room at 25 ° C. using a tensile tester (Intesco manufactured precision universal material tester, 2020 type). The peeling angle was 180 degrees, and the peeling speed was 300 mm / min. Peeling strength took the average value of the part where the intensity | strength of the spectrum was stable. The evaluation result was an average value of n = 5.

(4) Wrinkle A mold having an inner size of 220 mm × 55 mm × 1.5 mm was heated to 170 ° C., a release film was loaded, vacuum was applied, and held for 2 minutes. Thereafter, the evacuation was released to normal pressure, the release film was removed, and the presence or absence of wrinkles in the removed release film was visually confirmed. This operation was repeated 200 times to confirm the number of occurrences of wrinkles.

(5) Releasability Using a mold release film, processing with a molding apparatus was performed using the same mold as in (4) Wrinkle evaluation at a temperature setting of 170 ° C. The state of the release film and the package when the mold was opened after molding was visually observed and evaluated according to the following criteria.
Good: The film was completely removed from the package.
Normal: A part of the film peeled off while being pulled by the package when the mold opened.
Poor: The film did not peel off from the package and remained.

(6) Tearing Using a mold release film, processing with a molding apparatus was performed using the same mold as in the above (4) wrinkle evaluation at a temperature setting of 170 ° C. It was visually confirmed whether the release film was not broken when the mold was opened after molding. This operation was repeated 200 times and the number of occurrences of breakage was confirmed.

(7) Follow-up property In the processing of the above (6), with respect to the one in which the release film was not broken, the state of the corner portion and the side portion of the molded package was visually observed based on the followability of the release film. The number of occurrences of rounded packages was confirmed.

(8) Non-Defective Rate From the results of the above (6) and (7), the non-defective rate of the package obtained by 200 times of processing was calculated. The non-defective rate passed 80% or more.

Example 1
Hereinafter, polyester resins to be blended are referred to as a first resin, a second resin, and a third resin, from those having a high ratio.

  54 parts by mass of PBT (polybutylene terephthalate, IV (inherent viscosity) 1.08 dl / g, Tm (melting point) 223 ° C.) as a first resin, and PET (polyethylene terephthalate, IV 0.75 dl / g as a second resin g, Tm 255 ° C) dry blended with 46 parts by mass is melt extruded into a sheet at 275 ° C using an extruder equipped with a T-die, brought into close contact with a cooling drum with a surface temperature of 18 ° C, and cooled An oriented sheet was obtained. After holding the end of the obtained unstretched sheet in the width direction with the clip of the tenter type simultaneous biaxial stretching machine and traveling the preheating zone at 60 ° C., the temperature at 80 ° C. is applied to the MD (machine direction). The film was simultaneously biaxially stretched at 0 × and 3.3 in TD (width direction). Thereafter, heat relaxation was applied for 4 seconds at a temperature of 195 ° C., with a TD relaxation rate of 5%. Then, it was cooled to room temperature and wound up to obtain a simultaneously biaxially oriented polyester film. Thereafter, solvent addition reaction type silicone (KS-847T (Silicone A) manufactured by Shin-Etsu Chemical Co., Ltd.) diluted with toluene was hand-coated using a # 3 Meyer bar and then dried at 150 ° C. for 30 seconds. As a result, a 50 μm-thick release film on which a 0.2 μm-thick release resin layer was formed was obtained.

  The evaluation results of the release film obtained as described above are shown in Table 1.

(Examples 2, 3 and 16 to 18)
The composition ratio of PBT to PET was changed as shown in Table 1 as compared with Example 1. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Example 4)
A simultaneous biaxially stretched film was obtained in the same manner as Example 1. Thereafter, a resin composition X manufactured as follows was used as a release resin layer, and coated under the same conditions as in Example 1 to form a release resin layer having a thickness of 0.2 μm and a release of 50 μm in thickness. I got a film. The evaluation results of the obtained release film are shown in Table 1.

[Production of Resin Composition X]
Acid-modified polyolefin resin aqueous dispersion M manufactured as described below, 8% by weight aqueous solution of polyvinyl alcohol ("VC-10" manufactured by Nippon Shokubai Bi-Pobar, degree of polymerization: 1,000), and crosslinking agent Aqueous solution of an oxazoline compound (Epocross "WS-500", solid content concentration: 40% by mass, manufactured by Nippon Shokubai Co., Ltd.), polyvinyl alcohol is 50 parts by mass with respect to 100 parts by mass of acid-modified polyolefin resin, It mixed so that solid content might be 10 mass parts with respect to 100 mass parts of acid-modified polyolefin resin, and the liquid resin composition X was obtained.

[Production of Acid-Modified Polyolefin Resin Aqueous Dispersion M]
60.0 g of acid-modified polyolefin resin Y produced as described below using a stirrer equipped with a sealable pressure-resistant 1-liter glass container with a heater, and 45.0 g of Bu-EG (Wako Pure Chemical Industries, Ltd. (Special grade, boiling point 171 ° C, "Bu-EG" means ethylene glycol-n-butyl ether), 6.9 g (1.0-fold equivalent to the carboxyl group of the maleic anhydride unit in the resin) Of DMEA (manufactured by Wako Pure Chemical Industries, special grade, boiling point 134 ° C., where “DMEA” means N, N-dimethylethanolamine) and 188.1 g of distilled water in the above glass container and stirring The blade was stirred at a rotational speed of 300 rpm. At that time, no resin precipitation was observed at the bottom of the container, and it was confirmed that the container was in a floating state. Then, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the temperature inside the system was maintained at 140 ° C. and stirring was further performed for 60 minutes. Then, it cooled to room temperature (about 25 degreeC), stirring with air cooling at the rotational speed of 300 rpm. Further, pressure filtration (air pressure: 0.2 MPa) was performed using a 300 mesh stainless steel filter (wire diameter: 0.035 mm, plain weave) to obtain a milk-white, uniform, acid-modified polyolefin resin aqueous dispersion M. There was almost no residual resin on the filter.

[Production of acid-modified polyolefin resin Y]
280 g of a propylene-butene-ethylene terpolymer (made by Huls Japan, Bestplast 708, propylene / butene / ethylene = 64.8 / 23.9 / 11.3% by mass) in a four-necked flask After heating and melting in a nitrogen atmosphere, the temperature inside the system is maintained at 170 ° C., and 32.0 g of maleic anhydride as unsaturated carboxylic acid and 6.0 g of dicumyl peroxide as a radical generator under stirring. It was added over 1 hour and then allowed to react for 1 hour.

  After completion of the reaction, the obtained reaction product was poured into a large amount of acetone to precipitate a resin. The resin was further washed with acetone several times to remove unreacted maleic anhydride, and then dried under reduced pressure in a reduced pressure dryer to obtain acid-modified polyolefin resin Y.

(Example 5)
In the same manner as Example 1, an unstretched sheet was obtained. The unstretched sheet was introduced into a roll-type longitudinal stretcher, preheated at 45 to 55 ° C., and then longitudinally stretched at 60 to 70 ° C. in MD (machine direction) 3.0 times.

  After cooling to room temperature, the film was preheated at 75 ° C. while holding both ends in the width direction of the film, and transversely stretched at 85 to 95 ° C. in the TD (width direction) by 3.3 times. Further, after heat treatment at a temperature of 190 ° C. for 4 seconds, the film was cooled to room temperature and taken up to obtain a sequentially biaxially stretched film. Thereafter, the resin composition X was coated on the release resin layer under the same conditions as in Example 1 to obtain a release film having a thickness of 50 μm on which a release resin layer having a thickness of 0.2 μm was formed. The evaluation results of the obtained release film are shown in Table 1.

(Examples 6, 7)
In Example 6, a copolymer polyester (IPA4, Tm (melting point) 245 ° C.) in which 4 mol% of isophthalic acid is copolymerized is used as the second resin, instead of the PET homopolymer of Example 1. Were changed as shown in Table 1. In Example 7, in place of the PET homopolymer of Example 1, a copolymerized polyester (AD6, Tm (melting point) 240 ° C.) obtained by copolymerizing 6 mol% of adipic acid is used as the second resin. Were changed as shown in Table 1. In both of Examples 6 and 7, KS-3703 (Silicone B) manufactured by Shin-Etsu Chemical Co., Ltd. was used as the resin layer for peeling. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Examples 8 to 10)
The thickness of the release film was changed as shown in Table 1 as compared with Example 1. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Example 11)
The resin composition ratio was changed as shown in Table 1 as compared with Example 1, and the method of stretching the unstretched sheet was changed to the same sequential biaxial stretching method as in Example 5. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Examples 12 to 14)
Compared to Example 1, the first resin was changed. Specifically, in Example 12, as a first resin, a copolymerized PBT (modified PBT, Tm (melting point) obtained by copolymerizing 15 parts by mass of PTMG (polytetramethylene ether glycol) having an average molecular weight Mw of 1000 into polybutylene terephthalate ) 218 ° C) was used. In Example 13, polytrimethylene terephthalate (PTT, Tm (melting point) 228 ° C.) was used as the first resin. In Example 14, as the first resin, a copolymer polyester (AD15, Tm (melting point) 225 ° C.) obtained by copolymerizing 15 mol% of adipic acid was used, and the composition ratio was changed as shown in Table 1.
A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Example 15)
In Example 1, a copolymer polyester (AD6, Tm (melting point) 240 ° C.) obtained by further copolymerizing 6 mol% of adipic acid was used as a third resin, and the composition ratio was changed as shown in Table 1. Other than that was carried out similarly to Example 1, and obtained the release film. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 1)
As compared with Example 1, a release film was obtained as the same as Example 1 except that only the base film was used without providing the release layer. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 2)
In the same manner as Example 1, an unstretched sheet was obtained. However, about thickness, discharge amount was adjusted so that it might be set to 50 micrometers with an unstretched sheet. The stretching process and the subsequent heat setting process were not performed. The unstretched sheet was hand-coated with a silicone coat in the same manner as in Example 1 to obtain a release film. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 3)
Compared to Example 1, the first resin was changed to polylactic acid (PLA) having a Tm (melting point) of 165 ° C. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 4)
Compared to Example 1, the first resin was changed to the same PET as the second resin of Example 1, and the second resin was changed to polylactic acid having a Tm (melting point) of 165 ° C. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 5)
Compared to Example 11, a copolymer polyester (CHDM30, without Tm (melting point)) copolymerized with 30 mol% of cyclohexanedimethanol as the first resin and a copolymer polyester with 8 mol% of diethylene glycol copolymerized with the second resin Using (DEG8, Tm (melting point) 240 ° C.), the composition ratio was changed as shown in Table 1. A release film was obtained as in Example 11 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 6)
A copolymerized polyester (NPG 60, without Tm (melting point)) obtained by copolymerizing 60% by mole of neopentyl glycol in the second resin using the same PET as the second resin in Example 1 as the first resin in comparison with Example 11 Using it, the composition ratio was changed as shown in Table 1. Furthermore, the thickness was changed as shown in Table 1. A release film was obtained as in Example 11 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 7)
Compared to Example 1, the first resin was changed to the same PET as the second resin of Example 1, and the second resin was not used. Furthermore, the thickness was changed as shown in Table 1. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 8)
Compared to Example 1, the first resin was the same PBT as Example 1, but the second resin was not used. Furthermore, the thickness was changed as shown in Table 1. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 9)
Compared to Example 1, the first resin was changed to the same IPA 4 as the second resin of Example 6, and the second resin was not used. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

(Comparative example 10)
Compared to Example 1, the first resin was changed to a copolyester (AD8, Tm (melting point) 235 ° C.) obtained by copolymerizing 8 mol% of adipic acid, and the second resin was not used. A release film was obtained as in Example 1 except the above. The evaluation results of the obtained release film are shown in Table 1.

  The release film of Examples 1-18 was excellent in the moldability of a semiconductor package, and the external appearance of the obtained molded article was favorable. In particular, the release film of Examples 1, 4, 5, 8 and 11 has a film thickness in the most preferable range, contains PET as a base film in a more preferable range, and PBT in a more preferable range. Since it contained, the evaluation of a wrinkle, a tear, and conformity was a favorable result.

  On the other hand, the release film of Comparative Example 1 did not exhibit release properties because the release resin layer was not laminated. For this reason, when peeling a film, the same film was destroyed and it was not possible to measure peeling strength. When processed by a molding apparatus, the film did not come off from the package when the mold was opened, and the film was torn off as a trigger. The fragments of the film were attached to the package, and the followability could not be evaluated based on the condition of the package.

  The release film of Comparative Example 2 was poor in heat resistance because the base film was an unstretched polyester film, and when the film was peeled, the film was broken and the peel strength could not be measured. . In addition, the film shrank greatly under high temperature conditions for evaluation of wrinkles, wrinkles were generated, the mold releasability was inferior, and the film was broken. The fragments of the film were attached to the package, and the followability could not be evaluated based on the condition of the package.

  The release films of Comparative Examples 3 to 5 are inferior in heat resistance because PLA having a low melting point and CHDM 30 having a low crystallinity and no melting point are used, and when the film is peeled, the film is broken and the peeling strength is Could not be measured. In addition, the film shrank greatly under high temperature conditions for evaluation of wrinkles, wrinkles were generated, the mold releasability was inferior, and the film was broken. The fragments of the film were attached to the package, and the followability could not be evaluated based on the condition of the package.

  Although NPG60 with a low melting point was used for the release film of the comparative example 6, since the resin ratio was low, peeling strength was able to be measured. However, at the time of actual molding, the phenomenon that the wrinkles and a part of the film melt and break frequently occurred by performing repeated molding. The followability was good for those in which no breakage occurred during molding.

  The release films of Comparative Examples 7 and 9 did not use the second resin, so they were inferior in followability, and were also prone to wrinkles, and the phenomenon of film breakage triggered by the wrinkles frequently occurred.

  Comparative Examples 8 and 10 Since the second release film was not used, the heat resistance was inferior and wrinkles occurred. When processed by a molding apparatus, the generated wrinkles inhibited the releasability. Furthermore, the film was broken due to the wrinkles and also because the strength of the film was insufficient. The followability was good for those in which no tear occurred during molding.

  None of the release films of Comparative Examples 1 to 10 simultaneously satisfied all the required performances (wrinkling, releasability, tear, followability).

Claims (18)

A method of manufacturing a semiconductor package,
When a mold release film is disposed on a cavity surface filled with a thermosetting resin for package production in a mold in which a device to be packaged is installed, and then the thermosetting resin is filled in the mold,
As the release film, a laminated film in which a base film disposed on the cavity surface side and a peeling resin disposed on the thermosetting resin side are laminated,
A method for producing a semiconductor package, comprising using a stretched polyester film having a melting point at two or more points above a mold set temperature as the base film.   The method for producing a semiconductor package according to claim 1, wherein the polyester resin constituting the substrate film is one having a dicarboxylic acid component and / or a diol component containing an alkyl chain of 2 to 5 carbon atoms as a repeating component. .   The method for producing a semiconductor package according to claim 1 or 2, wherein a polyester resin containing 20 to 60 mass% of polyethylene terephthalate is used as the polyester resin constituting the base film.   The method for producing a semiconductor package according to any one of claims 1 to 3, wherein a polyester resin containing 40 to 80 mass% of polybutylene terephthalate is used as the polyester resin constituting the substrate film.   The method for producing a semiconductor package according to any one of claims 1 to 4, wherein a release film having a thickness of 20 μm to 100 μm is used. After holding at 5 kg / cm ² for 20 minutes with a press set at 170 ° C., it is characterized by using a release film having a peeling strength of 1.0 N / cm or less with respect to an epoxy prepreg which has been cooled and hardened to room temperature. The manufacturing method of the semiconductor package of any one of Claim 1 to 5. A semiconductor package in which a mold release film is disposed on a cavity surface filled with a thermosetting resin for manufacturing a package in a mold in which a device to be packaged is installed, and then the thermosetting resin is filled in the mold. The release film used in a manufacturing method, which is
In the release film, a base film disposed on the cavity surface side and a release resin disposed on the thermosetting resin side are laminated,
The release film for the manufacturing process of a semiconductor package, wherein the base film is formed of a stretched polyester film having a melting point at two or more points at a mold set temperature or more.   8. The mold release process for producing a semiconductor package according to claim 7, wherein the dicarboxylic acid component and / or the diol component of the polyester resin constituting the base film contains an alkyl chain having 2 to 5 carbon atoms as a repeating component. the film.   The polyester film which comprises a base film contains 20-60 mass% of polyethylene terephthalates, The release film for the manufacturing process of the semiconductor package of Claim 7 or 8 characterized by the above-mentioned.   The polyester resin which comprises a base film is what contains 40-80 mass% of polybutylene terephthalates, The separation for the manufacturing process of the semiconductor package of any one of Claim 7 to 9 characterized by the above-mentioned. Mold film.   The release film for the manufacturing process of a semiconductor package according to any one of claims 7 to 10, which has a thickness of 20 μm to 100 μm. After holding at 5 kg / cm ² for 20 minutes with a press set at 170 ° C., the peel strength from the epoxy prepreg cured and cooled to room temperature is 1.0 N / cm or less. 11. A mold release film for the manufacturing process of a semiconductor package according to any one of the items 1 to 11. A release film in which a base film disposed on the cavity surface side of a molding die and a release resin disposed on the molding resin side are laminated,
A release film characterized in that the base film is a stretched polyester film having a melting point at two or more points above a mold set temperature.   14. The release film according to claim 13, wherein the dicarboxylic acid component and / or the diol component of the polyester resin constituting the substrate film comprises an alkyl chain of 2 to 5 carbon atoms as a repeating component.   The polyester film which comprises a base film contains 20-60 mass% of polyethylene terephthalates, The release film of Claim 13 or 14 characterized by the above-mentioned.   The release film according to any one of claims 13 to 15, wherein the polyester resin constituting the substrate film contains 40 to 80 mass% of polybutylene terephthalate.   The release film according to any one of claims 13 to 16, wherein the thickness is 20 μm to 100 μm. 18. The method according to any one of claims 13 to 17, characterized in that the peel strength with respect to the epoxy prepreg which has been cooled to room temperature and cured after holding at 5 kg / cm ² for 20 minutes with a press set at 170 ° C. is 1.0 N / cm or less. The release film according to any one of the above.

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