JP5773824B2 - Release film - Google Patents

Description

  The present invention relates to a mold release film used for molding an optical semiconductor element or a semiconductor element, in particular, for molding an LED lens.

  For example, optical semiconductor elements such as LEDs, photoisolators, phototransistors, photodiodes, CCDs, CMOSs, and semiconductor elements such as transistors, ICs, LSIs, and super LSIs are encapsulated with silicone rubber compositions or epoxy resin compositions. And is sealed by molding.

  A molding apparatus is used for sealing the above-described optical semiconductor element or semiconductor element, and a silicone rubber composition or an epoxy resin composition is filled into a mold as a sealing material and molded.

  As a method for releasing the mold and the molded product, for example, a method in which a release film is interposed between the mold and the sealing material to be filled has been put into practical use (see Patent Document 1). The release film is supplied Roll-to-Roll in the mold forming apparatus, enters the mold that is temperature-controlled at the molding processing temperature, is sucked in vacuum and is in close contact with the mold, and then filled with a sealing material Is done. When the mold is opened after a certain time, the molded product is peeled off from the mold release film while the mold release film is sucked into the mold. The release film includes, for example, a single layer made of a thermoplastic fluororesin tetrafluoroethylene-ethylene copolymer resin (ETFE resin) or a tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP resin). A film is used (see Patent Document 2).

  However, when such a release film is used for molding an LED lens using a silicone rubber composition as a sealing material, for example, for a bullet-shaped lens shape having a bottom surface of about φ6 mm and a height of about 4 mm, Even if the release film is sucked in a vacuum, the film may not be stretched. Even if it is stretched, it does not adhere to the mold, and there is a problem that an LED lens as designed can not be obtained. Further, if the release film is thinned to improve the elongation, there is a problem that the release film is cut at the edge of the mold when sucked in vacuum. As described above, when the molding magnification (ratio of the film area after molding to the film area before molding) during vacuum molding of the release film is twice or more, the above-mentioned problems are likely to occur.

  Moreover, the method of using the film which consists of a crystalline aromatic polyester containing resin composition which contains butylene terephthalate in a crystal | crystallization component is known as a mold release film (refer patent document 3).

  However, as shown in Patent Document 3, when a film made of a resin composition containing a crystalline aromatic polyester containing butylene terephthalate is used for molding an LED lens, the release film is sucked in vacuum as shown in Patent Document 3. In this case, although it adheres to the mold, it is stretched beyond the yield point, so that the release film is partially thinned, and there is a problem that irregularities and wrinkles occur on the surface of the molded LED lens. In addition, addition type liquid silicone rubber is used as the silicone rubber composition, but the compound present in the release film becomes a catalyst poison of the addition type liquid silicone rubber, which inhibits curing, and There is a problem that the contact surface does not cure and the gel-like adhesive remains. For this reason, in the molding of LED lenses with addition-type liquid silicone rubber, there is actually no film that can be suitably used as a release film.

JP-A-8-142105 JP 2001-310336 A JP 2007-224311 A

  The present invention has been made in view of the above, and is a mold release film excellent in releasability from a mold or a molded product in the molding of an addition type liquid silicone rubber, and the shape of the mold is a design dimension. As well as being excellent in mold shape transferability that is transferred to the molded product as it is, surface smoothness of the molded product can be obtained without leaving a gel-like adhesive on the surface of the molded product. It aims at providing the film for mold release which also has property.

In order to solve the above-mentioned problems, the release film of the present invention is characterized by including a fluorine-containing polymer having a melting point of 140 ° C. or higher and a storage elastic modulus at 140 ° C. in dynamic viscoelasticity in the flow direction (MD direction). and width up direction (TD direction) der both 50MPa or less, the fluorine-containing polymer is summarized in that a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer.

  The fluorine-containing polymer according to the release film of the present invention further includes one or more additives belonging to an antioxidant, a heat stabilizer, an inorganic filler such as silica particles, an antistatic agent, a lubricant, a colorant, and a pigment. Can be included.

  The release film of the present invention is preferably used when resin-molding an optical semiconductor element or a semiconductor element.

  The release film of the present invention is preferably used when molding an LED lens made of a silicone resin composition.

  According to the present invention, the mold and the molded product are excellent in releasability, and the mold shape is transferred to the molded product according to the design dimensions, and the gel shape is formed on the surface of the molded product. The surface smoothness of the molded product can be obtained without leaving an adhesive, and furthermore, a release film having heat resistance can be provided.

It is a side view of a bullet type LED lens concerning an embodiment of the present invention. (A) It is a top view of the metal mold | die of the bullet type LED lens which concerns on embodiment of this invention. (B) It is an AA arrow sectional view of Drawing 2 (a) of a metallic mold of a bullet type LED lens concerning an embodiment of the present invention. It is a figure which shows schematic structure of the film manufacturing apparatus of the film for mold release which concerns on embodiment of this invention. It is sectional drawing which shows the periphery of the material insertion hopper of the film manufacturing apparatus shown in FIG. 3 based on embodiment of this invention.

  As a result of various studies to achieve the above object, the present inventors have made a fluorine-containing polymer having a melting point of 140 ° C. or higher, and have a storage elastic modulus at 140 ° C. of dynamic viscoelasticity of 50 MPa or less. The film has excellent releasability from molds and molded products, and has excellent mold shape transferability that allows the mold shape to be transferred to the molded products according to the design dimensions. It has been found that the surface smoothness of the molded product can be obtained without remaining, and that it can also have heat resistance.

Examples of the fluorine-containing polymer in the present invention include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA). Tetrafluoroethylene / ethylene copolymer (ETFE), Tetrafluoroethylene / ethylene / propylene copolymer, Tetrafluoroethylene / ethylene / perfluoroalkyl vinyl ether copolymer, Tetrafluoroethylene / ethylene / heptafluoropentene Copolymer, Tetrafluoroethylene / ethylene / (perfluorobutyl) ethylene copolymer, Tetrafluoroethylene / ethylene / hexafluoropropylene copolymer, Tetrafluoroethylene / propylene copolymer, Tetrafur Oroethylene / propylene / vinylidene fluoride copolymer, tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / hexafluoropropylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / hexafluoro Propylene / vinylidene fluoride copolymer (THV), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride / tetrafluoroiodopropoxytrifluoroethylene copolymer, tetrafluoroethylene / vinylidene fluoride copolymer, chlorotrifluoroethylene・ Ethylene copolymer, chlorotrifluoroethylene / vinylidene fluoride copolymer, vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / Examples thereof include polymers such as trifluoroethylene copolymers or copolymers, and may be grafts, blocks, and blend polymers of these polymers. For example, vinylidene fluoride copolymers may be added to chlorotrifluoroethylene / vinylidene fluoride. Examples include a graft copolymer of a ride copolymer, a block polymer of a tetrafluoroethylene / ethylene copolymer and a vinylidene fluoride / hexafluoropropylene copolymer. Any one of these may be used alone, or two or more of them may be mixed and used. Among these, PVDF, PVF, THV, tetrafluoroethylene / vinylidene fluoride copolymer, chlorotrifluoroethylene / vinylidene fluoride copolymer, vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / trifluoro Ethylene copolymers are preferred and THV is particularly preferred. Examples of commercially available products include Dionion THV series (X310G, 400G, 415G, 500G, 500GZ, 610G, 610GZ, 815G, and 815GZ) sold by Sumitomo 3M Limited.

  If necessary, various additives may be added to the fluorine-containing polymer as long as the characteristics of the present invention are not impaired. For example, antioxidants, heat stabilizers, inorganic fillers such as silica particles, antistatic agents, lubricants, colorants, pigments and the like can be mentioned. As the antistatic agent, nonionic surfactants, anionic surfactants, cationic surfactant systems, zwitterionic surfactant systems, π electron conjugated polymers, and conductive carbon black are preferable.

  The melting point of the fluorine-containing polymer used in the present invention (melting peak temperature determined at 20 ° C. per minute by differential scanning calorimetry according to JIS K7121) is 140 ° C. or higher, preferably 140 to 250 ° C., 150 -230 degreeC is more preferable. Since the molding temperature of the addition-type liquid silicone rubber is about 120 to 140 ° C., if the melting point of the fluorine-containing polymer is less than 140 ° C., the release film shrinks or melts or melts during molding. There are concerns. On the other hand, when the melting point exceeds 250 ° C., the storage elastic modulus at 140 ° C. of the release film tends to exceed the desired range.

  The film for mold release of the present invention has a storage elastic modulus at 140 ° C. in dynamic viscoelasticity of 50 MPa or less, preferably 0.1 to 50 MPa, and more preferably 0.5 to 45 MPa. If the storage elastic modulus at 140 ° C. is too high, the release film may not be stretched even if it is sucked in vacuum, and even if stretched, it does not adhere to the mold, and the desired dimensions cannot be obtained. This causes a problem such as tearing at the edge. In particular, when the molding magnification (ratio of the film area after molding to the film area before molding) is 2 times or more, such a problem is likely to occur, which is not preferable. On the other hand, when the storage elastic modulus at 140 ° C. is too small, there is a concern that the mold release film may be wrinkled or melted during molding.

  The release film of the present invention can be formed by a conventionally known method such as a melt extrusion method, a melt cast method, or a calendar method, and the melt extrusion method is preferable because of high productivity. Examples of the melt extrusion method include a T-die method and an inflation method. In the following example, a method for forming a release film by a melt extrusion method using a T-die will be described.

  The mold release film obtained by such a method uses an extruder such as a single screw extruder or a twin screw extruder for the fluorine-containing polymer, and the gap between the extruder and the molding material depends on the characteristics of the fluorine-containing polymer. In the atmosphere where the air present in the atmosphere is replaced with nitrogen gas, the release film melt-extruded from the lip portion at the tip of the T die disposed at the tip of the extruder is pressed with a pressure roll and a cooling roll in the take-up machine It is obtained by directly sandwiching and cooling between them, or by inserting a separator from both the pressure roll side and the cooling roll side or one side to cool by sandwiching, and then winding them sequentially on a take-up tube with a winder.

  FIG. 3 is a configuration diagram showing an outline of a film production apparatus for producing a release film by the above-described method. 4 is a cross-sectional view of the periphery of the material charging hopper of the film manufacturing apparatus shown in FIG. In FIG. 3, the film manufacturing apparatus is generally configured to include a material charging hopper 2, an extruder 1, a T die 7, a take-up machine 11, and a winder 15. The material charging hopper 2 is configured to input a molding material, and as shown in FIG. 4, the nitrogen gas supply pipe 3 is connected to the extruder 1 of the material charging hopper 2 through the spacer 3a while being connected to the extruder 1. Inserted. The nitrogen gas supply pipe 3 is bent so as to be substantially along the central axis of the material charging port 1 c, and the tip thereof extends to the vicinity of the outer periphery of the extrusion screw 1 a in the extruder 1. Oxygen contained in the molding material fed from the material feeding hopper 2 or in the extruder 1 is supplied to the nitrogen gas supply pipe 3 when the molding material is mixed and stirred by the extrusion screw 1a of the extruder 1. It will be replaced with nitrogen gas.

  The extruder 1 mixes and stirs the molding material with the extrusion screw 1a, conveys it in the direction of arrow B, and heats and melts the molding material by electric heating means incorporated in the cylinder 1b of the extruder 1. The molding material thus melted and conveyed is fed to the filter means 5 through the connecting pipe 4 shown in FIG. The unmelted molding material is separated by the filter means 5 and the molten molding material is fed to the gear pump 6. In the gear pump 6, the molten molding material is pushed out to the T die 7 while increasing the pressure of the molten molding material. In the T die 7, the melt molding material is extruded at a predetermined pressure, and a film 8 having a predetermined thickness and a predetermined width is formed from the lip portion 7 a of the T die 7. The film 8 formed in this manner is adjusted to a predetermined thickness by the pressure-bonding roll 9 while being drawn on the outer peripheral surface of the cooling roll 10 of the take-up machine 11, and further cooled and solidified. It is conveyed to the winder 15.

  In the winder 15, the film 8 is guided by the guide rolls 15 a, 15 b, and 15 c and is wound by the winding tube 16. In addition, a thickness measuring device 14 is disposed between the conveying roll pairs 12 and 13 and the guide roll 15a, and the thickness measured by the thickness measuring device 14 is set so as to obtain a desired thickness. Based on this, the peripheral speed of the cooling roll 10 is adjusted and controlled. Thereby, the release film is formed.

  The release film may be formed in the surface shape of the film according to the surface shape required by the molded product. For example, when the surface of the LED or the like is a mirror surface, a release film in which the surface of the release film is a mirror surface is used. In addition, since ICs, LSIs, and the like have fine irregularities formed on the surface thereof, a release film having fine irregularities formed on the surface of the release film is used.

  As a method of forming the surface shape of the mold release film, when the surface is mirror-finished, the surface of the metal cooling roll described above is mirror-finished, and the mold release film in a molten state is placed on the cooling roll. There is a method in which the surface of the release film is mirror-finished by pressure bonding with a pressure roll. When using a separator, there is a method of using a mirror-finished PET film or OPP film as the separator and transferring the surface thereof.

  When forming fine irregularities on the surface of the mold release film, fine irregularities are formed on the outer peripheral surface of the metal cooling roll described above, and the mold release film in a molten state is pressure-bonded to the cooling roll. There is a method of transferring fine irregularities formed on the outer peripheral surface of the cooling roll onto the surface of the release film when crimping with a roll. Moreover, when using a separator, there exists the method of using the PET film and OPP film which carried out the mat processing of the surface as a separator, and transferring the surface.

  When the surface of the release film is a mirror surface, the surface roughness is measured at a speed of 0.6 mm / second, a cutoff value of 0.8 mm, and an evaluation length of 8.0 mm in accordance with JIS B0601-2001. The surface may be appropriately formed so that the arithmetic average roughness Ra is 0.10 or less and the maximum height roughness Rz is 1.00 or less. When the arithmetic average roughness Ra is 0.10 or less and the maximum height roughness Rz is 1.00 or less, the surface of the molded product to which the surface of the release film is transferred becomes smooth.

  When fine irregularities are formed on the surface of the release film, the arithmetic average roughness Ra measured by the same method as described above is 0.5 or more, and the maximum height roughness Rz is 5.00 or more. The surface may be appropriately formed so that

  The release film of the present invention has a thickness in the range of 5 μm to 500 μm, preferably in the range of 10 μm to 400 μm, and may be appropriately selected according to the shape of the mold to be used. If the thickness of the release film is less than 5 μm, when following the mold during use, the release film will be stretched and thinned, or it may be broken by the pressure of the sealing material. It is not preferable. If the thickness exceeds 500 μm, the thickness of the release film becomes an obstacle, and it becomes impossible to follow a mold having a fine structure, or the complicated shape of the mold cannot be transferred to the molded product. It is not preferable.

  Examples are shown below, but the present invention is not limited by these.

The materials (a), (b), (c), (d), (e), and (f) of the release film used in order in Examples 1 to 4 and Comparative Examples 1 and 2 shown in Table 1 are as follows. It is as follows.
(A) THV415G: trade name, manufactured by Dinion, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer, melting point 155 ° C.
(B) THV500GZ: trade name, manufactured by Dinion, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer, melting point 165 ° C.
(C) THV610GZ: trade name, manufactured by Dinion, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer, melting point 185 ° C.
(D) THV815G: trade name, manufactured by Dinion, tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer, melting point 225 ° C.
(E) Aflex 25N-1250NT: trade name, manufactured by Asahi Glass Co., Ltd., tetrafluoroethylene / ethylene copolymer, melting point 260 ° C.
(F) Aflex 100KN-500NT-10: trade name, manufactured by Asahi Glass Co., Ltd., tetrafluoroethylene / ethylene copolymer, melting point 260 ° C.

  Hereinafter, production of a release film, measurement of storage elastic modulus, peelability, heat resistance, mold size transferability, surface smoothness, and actual usability will be described in detail based on Table 1. The same applies to the comparative example.

(Preparation of release film)
Fluorine-containing polymer is fed to a single screw extruder (manufactured by Tanabe Plastics Machinery Co., Ltd.) with a diameter of 30 mm and L / D = 28, and a cylinder temperature of 230 ° C. to 270 ° C. using a full flight extrusion screw with a compression ratio of 2.9. The mixture was melt-kneaded under the conditions, and continuously extruded from a T die having a width of 500 mm under the conditions of a die temperature of 260 ° C to 270 ° C. The extruded release film is cooled by being sandwiched between a pressure roll and a cooling roll in a take-up machine, and both ends are cut with a slit blade in a winder, and the release film is taken up on a take-up tube. Thus, a release film having a thickness of 300 mm and a length of 50 m was produced with the thickness shown in Table 1. The release film has a matte surface on the pressure-bonding roll side and a mirror surface on the cooling roll side.

(Measurement of storage modulus)
For each of the flow direction (MD) and width direction (TD) of the release film, SOLIDS ANALYZER RSAII [trade name] manufactured by Rheometrix is used, tensile mode, frequency 1 Hz, heating rate 5 ° C./min, strain 0 The storage modulus at a temperature of 140 ° C. was measured under the condition of 1%. The results are shown in Table 1.

(Method of evaluation)
FIG. 1 is a side view of a bullet-type LED lens 20 having lead wires 21a and 21b. The evaluation is performed using the mold shown in FIGS. 2A and 2B having the lens shape shown in FIG. After adsorbing, the silicone rubber composition was dropped and subjected to hot press molding, and peelability, heat resistance, mold size transferability, and surface smoothness were evaluated.

Specifically, the mold release film is stretched so that the mold surface is the mold side and the mirror surface is the air side of the mold heated to 140 ° C. The film was adsorbed on the mold. Next, a silicone rubber composition RHODORSIL RTV141 (manufactured by BLUESTAR SILICONES) is dropped onto the release film, and a flat metal mold whose surface is hard chrome plated is pressed onto the film, and is sandwiched between the two molds and hot pressed. Molded. The molded laminate was evaluated for peelability between the release film and the cured silicone rubber, heat resistance of the release film, and mold size transferability and surface smoothness of the cured silicone rubber. Hot press molding was performed under conditions of a temperature of 140 ° C. and a pressure of 10 kg / cm ² for 5 minutes. The molding magnification at one portion of the bullet-shaped lens molding portion in FIG. 2 is about 2.7 times in calculation.

(Peelability)
In the evaluation of peelability, when the cured silicone rubber composition could be peeled without remaining on the release film, “◯”, the silicone rubber composition was partially broken and remained on the release film The case is shown as “×”.

(Heat-resistant)
Evaluation of the heat resistance is to visually observe the release film from which the cured silicone rubber composition has been peeled off. If the film shape is maintained without melting or fusing, "○", melted into the release film, The case where fusing occurred was indicated as “x”.

(Mold dimension transferability)
Mold dimension transferability was evaluated by measuring the dimensions of the cured silicone rubber composition. The lens height evaluation criteria is further within a range of -0.1 mm from the dimension obtained by reducing the thickness of the release film for a hole depth of 4 mm, that is, ((4-release film thickness) -0. 1) It was set to mm or more. A case where all the 25 lenses were within the standard was indicated by “◯”, and a case where even one lens did not satisfy the standard was indicated by “X”.

(Surface smoothness)
For the surface smoothness, the surface state of the cured silicone rubber composition was visually evaluated. The case where there was no unevenness or wrinkles on the surface of the silicone rubber was indicated as “◯”, and the case where there were unevenness or wrinkles was indicated as “x”.

(Actual usability)
The actual usability was confirmed and evaluated by resin molding with a molding apparatus. Specifically, in the molding apparatus G-LINE manual press (trade name) manufactured by Apic Yamada as the molding device, RHODORSIL RTV141 (trade name manufactured by BLUESTAR SILICONES) is used as the silicone rubber composition, and the actual usability is visually confirmed. Confirmed by

In the evaluation of actual usability, “○” is given when all of the following items are satisfied, and “X” is given when there is a defect.
(1) The film was supplied without loosening when the release film was conveyed in the molding apparatus.
(2) There was no wrinkle on the film during adsorption.
(3) The peelability between the release film and the silicone rubber composition was good after hot press molding.
(4) The cured silicone rubber composition was molded into a desired shape and was smooth with no irregularities or wrinkles on the surface.
(5) The mold release film was not torn or melted, the silicone rubber composition was not left, and the mold was not soiled.

  From these results, the ETFE film having a thickness of 25 μm of Comparative Example 1 could not be actually used because the film was torn when adsorbed in the mold. The ETFE film having a thickness of 100 μm of Comparative Example 2 was inferior in mold size transferability, and the practical useability was not obtained because the cured silicone rubber composition was not formed into a desired shape.

  On the other hand, the release film of each example according to the present invention has heat resistance in addition to obtaining releasability, excellent mold size transferability and surface smoothness, and is further practically usable. It is clear that it has been granted. From this, according to the present invention, it is possible to obtain a release film that is excellent in releasability from a molded product obtained by molding a sealing material and that can provide a molded product having excellent shape and surface properties. it can.

  As described above, the release film of the example of the present invention was evaluated for the molding mold of the LED lens made of the silicone resin composition. However, the release film of the present invention is a resin mold for an optical semiconductor element or a semiconductor element. Needless to say, it is also useful for molding.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. Further, it is apparent from the scope of the claims that embodiments with such changes or improvements can also be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Material input hopper 3 Nitrogen gas supply pipe 4 Connection pipe 5 Filter 6 Gear pump 7 T die 7a Lip part 8 Film 9 Crimp roll 10 Cooling roll 11 Take-up machine 12, 13 Conveying roll pair 14 Thickness measuring device 16 rolls Pipes 17a, 17b Delivery rolls 18a, 18b Separator 20 Cannonball type LED lenses 21a, 21b Lead wire 30 Mold die 31 Lens molding recess

Claims (4)

Melting point comprises a fluorine-containing polymer above 140 ° C., Ri der storage modulus machine direction (MD direction) and width direction (TD direction) in both 50MPa or less at 140 ° C. in dynamic viscoelasticity, the fluorine-containing polymer A release film characterized by being a tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer . The thermoplastic elastomer composition further comprises one or more additives belonging to an antioxidant, a heat stabilizer, an inorganic filler such as silica particles, an antistatic agent, a lubricant, a colorant, and a pigment. The release film according to claim 1 . The release film according to claim 1 or 2 , wherein the release film is used when an optical semiconductor element or a semiconductor element is molded by resin molding. The release film according to any one of claims 1 to 3, wherein the release film is used when an LED lens made of a silicone resin composition is molded.

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