Release film for metal molding

Abstract

To provide a mold release film that is excellent in flexibility and heat resistance when heated, has good followability to a mold during resin molding, achieves molding according to the mold shape, is excellent in mold removal from the mold, and facilitates the disposal after use.SOLUTION: A mold release film for mold forming consists of two layers of a base film having 20 to 100 μm thickness and a release layer having 0.1 to 10 μm thickness, and the base film is polypropylene.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a release film for mold molding, and in particular to a release film that is placed on the upper, lower, or both surfaces of a molding die when directly sealing semiconductor elements, wafers, and even LEDs with liquid epoxy resin or silicone resin, or when molding a lens onto an LED element. [Background technology]

[0002] In recent years, molding has become mainstream for sealing semiconductor devices, LEDs, etc. It has become common to use molding to seal epoxy resin-based, silicone resin-based, and polyimide-based sealing resins, mainly through compression molding and transfer molding. During molding, a film is used for the purpose of releasing from the mold surface, which is called film molding. For example, Patent Document 1 describes a release sheet made of a polytetrafluoroethylene layer and a silicone layer. Patent Document 2 describes a release film made of various heat-resistant resin layers and a release layer.

[0003] If the above-mentioned sealing is performed without a release film, problems will occur such as the resin adhering to the mold during molding, or the resin penetrating into the ejector pins or gaps in the mold. To prevent such problems, the current general method is to place a release film on the top, bottom, or both sides of the molding mold.

[0004] The release film used here is made of fluororesin due to its heat resistance and releasability. However, problems with fluororesin include its price and the disposal of used release film, and so alternatives are being actively investigated. For example, PET film has been widely considered as a release film, but due to its high softening temperature and high elasticity, the resin that flows in under molding pressure does not fill the edges of the mold, resulting in a molded product that does not maintain the exact mold shape. PET resin has the problem of being unable to obtain the exact mold shape due to its insufficient mold conformability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Published Patent Publication No. 2006-231916 [Patent Document 2] International Publication No. WO2020 / 045338 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a release film which does not cause such problems at all, has excellent flexibility and heat resistance when heated, has good conformability to a mold during resin molding, can be molded according to the shape of the mold, and is easy to remove from the mold and to dispose of after use. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides A mold release film for mold forming, The release film for mold molding is composed of two layers: a base film having a thickness of 20 to 100 μm and a release layer having a thickness of 0.1 to 10 μm, and The base film is polypropylene.

[0008] Such a release film has excellent flexibility and heat resistance when heated, has good conformability to the mold during resin molding, can be molded to the shape of the mold, and is easy to remove from the mold and to dispose of after use.

[0009] The polypropylene is preferably a polypropylene film formed by inflation molding.

[0010] Polypropylene resin molded by the inflation method is produced by forming a film from a resin with a high purity and low additive content, so there is no migration of additives into the molded product and the adhesion to the release layer is higher.

[0011] The thermal elastic modulus of the polypropylene is preferably 100 to 1000 MPa at 100°C, 20 to 300 MPa at 120°C, and 1 to 50 MPa at 150°C.

[0012] Such a thermal elastic modulus makes the release film more suitable for molding with a mold.

[0013] The release layer is preferably made of a silicone resin.

[0014] Such a release layer provides better releasability.

[0015] In addition, the release film for mold molding of the present invention may be one in which both sides of the polypropylene are treated to have a pear-shaped texture without embossing.

[0016] Alternatively, both sides of the polypropylene may be treated to have a mirror finish.

[0017] The surface shape of polypropylene (PP) film can be either glossy or matte, and can be selected according to the resin to be molded, the shape of the molded product, and the application. Effect of the Invention

[0018] The release film for mold molding of the present invention has a polyolefin polypropylene whose thermal behavior is suitable for mechanical molding at molding temperatures of 60 to 160°C, and the adhesion between polypropylene, which is difficult to bond, and the silicone release layer provides excellent moldability and releasability, as well as improved productivity of semiconductor parts and the precision of molded products.

[0019] In addition, the release film for mold molding of the present invention is less expensive than fluorine-based films and is therefore economically superior. Furthermore, the disposal of fluorine-based films generates hydrofluoric acid and cannot be incinerated, which poses the problem of having to request a specific waste disposal company to carry out burial processing, etc., but the release film for mold molding of the present invention is a polyolefin-based film, so it can be easily incinerated and is therefore economically and environmentally superior.

[0020] On the other hand, a film in which a PET film is coated with a release agent has been studied as a film with low cost, but there is a problem that the elastic modulus is high and the mold followability is poor at temperatures below 150° C., making it difficult to obtain the desired shape. However, the release film for mold molding of the present invention is a release film that is flexibly released to the mold during mold molding at 60 to 160° C., maintains a good shape, and is excellent in release from the mold after curing. [Brief description of the drawings]

[0021] [Figure 1] 1 is an example of a cross-sectional view of a release film for mold molding of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of a die molding process in the examples and comparative examples. [Diagram 3] FIG. 2 is an explanatory diagram of a method for evaluating the dimensional accuracy of a die in the examples and comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] As described above, there has been a demand for the development of a release film that has excellent flexibility and heat resistance when heated, has good conformability to the mold during resin molding, can be molded to the shape of the mold, and is easy to remove from the mold and to dispose of after use.

[0023] As a result of extensive research to achieve the above-mentioned objective, the inventors have discovered that by using polypropylene as a base material and coating it with a silicone release layer, a release film can be produced that has excellent shape stability, followability and releasability, and is also easy to dispose of.

[0024] That is, the present invention relates to a release film for mold molding, which comprises two layers: a base film having a thickness of 20 to 100 μm and a release layer having a thickness of 0.1 to 10 μm, and the base film is made of polypropylene.

[0025] Hereinafter, the release film for mold molding of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited thereto.

[0026] Release film for metal molding 1 is a schematic cross-sectional view of a release film for mold molding of the present invention. The release film for mold molding 1 of the present invention is formed by laminating, in this order, a base film 11 having a thickness of 20 to 100 μm and a release layer 12 having a thickness of 0.1 to 10 μm, and the base film 11 is made of polypropylene.

[0027] Base Film The base film 11 used in the present invention is not particularly limited as long as it is made of polypropylene. For example, polypropylene resin molded by an inflation method, oriented polypropylene, or polypropylene resin formed into a film by T-die molding can be used.

[0028] These polypropylene resins have a heat resistance of 120 to 130°C during continuous use, and can be used at 120 to 160°C for short periods of time, and the most important deflection temperature under load is low among thermoplastic resins, at 40 to 90°C. In addition, with a bending stress of 40 to 60 MPa and a compressive yield stress of 35 to 60 MPa, polypropylene resin is a material that satisfies all the necessary characteristics for a release film for molding.

[0029] Furthermore, the polypropylene resin may be appropriately filled with an inorganic material such as talc or fine silica, or an organic material such as cellulose nanofiber.

[0030] Among these polypropylene resins, polypropylene resins molded by inflation molding, in which resins with a low amount of additives and high purity are used to form a film, are preferred. Polypropylene resins formed into a film by stretching or T-die molding contain heat-resistant additives, plasticizers, etc., and from the viewpoint of making hardening with the silicone resin of the release layer and poor adhesion even less likely to occur, and from the viewpoint of further reducing the risk of additives, etc. migrating to the molded product, are more preferred.

[0031] The thickness of the base film 11 is 20 to 100 μm. If the thickness of the base film is less than 20 μm, the base film is easily torn by the molding pressure at the molding temperature, and if the thickness of the base film exceeds 100 μm, the base film becomes too thick and the mold conformability decreases, making it impossible to maintain the mold shape. The thickness is preferably 30 to 80 μm.

[0032] The surface shape of polypropylene (PP) film can be either glossy or matte, and can be selected according to the resin to be molded, the shape of the molded product, and the application. For example, polypropylene with matte finish on both sides or only one side, polypropylene with mirror finish on both sides, etc. can be used.

[0033] When using a polypropylene (PP) film with a matte finish on one side, it is preferable to form the release layer on the matte finish. If the release layer is a release film formed on the matte finish, the release property with the molded resin is improved, and the surface of the molded resin is given an anti-slip effect and the texture can be improved.

[0034] There is no particular limitation on the method for treating the surface of polypropylene to have a pear-like texture, but for example, even without mechanical embossing, the pear-like texture can be generated by strain caused by the temperature difference between the inside and outside when the film is inflated and cooled, which reduces foreign matter contamination. Furthermore, these films can be multi-layered using a heated laminator to adjust the thickness.

[0035] The thermoelastic modulus of polypropylene is preferably 100 to 1000 MPa at 100° C., 20 to 300 MPa at 120° C., and 1 to 50 MPa at 150° C. Such a thermoelastic modulus makes the release film more suitable for mold molding. In the present invention, the thermoelastic modulus is measured according to JIS K 7127 Autograph Film Test Method.

[0036] release layer A release layer 12 having a thickness of 0.1 to 10 μm is formed on the above-mentioned base film 11. The release layer 12 is a layer for imparting releasability to the resin to be molded.

[0037] From the viewpoint of excellent heat resistance and contamination resistance, silicone resin is desirable for the release layer 12. Various types of silicone release agents can be used for the release layer, such as solventless, solvent, emulsion, and UV curing types, and the type is selected based on the type of substrate, release characteristics, processability, etc.

[0038] For example, X-62-2829, KS-847H, X-62-1873, X-62-6068, KF-2005 (all manufactured by Shin-Etsu Chemical Co., Ltd.) can be used. For this application, solvent-based X-62-2829 and KS-847H, which have excellent processability and releasability, are preferred. In particular, X-62-2829 is more preferred.

[0039] The thickness of the release layer is in the range of 0.1 to 10 μm. If the release layer is thicker than 10 μm, there is a risk of migration to the molded product or detachment. For this reason, it is preferable that the release layer is thin, but if it is thinner than 0.1 μm, releasability cannot be obtained. EXAMPLES

[0040] The configuration and the effects of the present invention will be described in more detail below through examples and comparative examples. These examples are provided to more specifically explain the present invention, and the scope of the present invention is not limited to these examples.

[0041] <Example 1> Substrate film: Polypropylene. A 50 μm-thick mirror-finished substrate film produced by Shin-Etsu Film Co., Ltd. using the inflation method was used.

[0042] The release layer was made by mixing Shin-Etsu Chemical's silicone release agent "X-62-2829", Shin-Etsu Chemical's platinum catalyst "CAT PL-50T", and toluene as a solvent in a ratio of 100:1:450. The mixture was applied to polypropylene using an applicator, and then heated at 120℃ for 1 minute to dry and harden, producing a release film with a release layer of an average thickness of 1.0μm.

[0043] Next, as shown in Fig. 2(a), a mold consisting of an upper mold 21 and a lower mold 22 was used, a release film 1 was placed on the lower mold 22, and molding was performed using a compression molding device with Shin-Etsu Chemical's KMC-2280HT as the molding resin 3 under the following molding conditions to obtain a molded product 4 shown in Fig. 2(b). Mold temperature: 150°C, molding pressure: 40 MPa, molding time: 5 minutes. The evaluation results of the mold releasability of the molded product after hardening and molding, the dimensional accuracy relative to the mold, and the shape retention determined from the dimensional accuracy are shown in Table 1.

[0044] As shown in Figure 3, the dimensional accuracy was evaluated in three stages based on the edge angle of the molded product: acute angle, nearly acute angle, and R shape.

[0045] <Example 2> Substrate Film: Polypropylene A release film was prepared in the same manner as in Example 1, except that a mirror-finished substrate film having a thickness of 30 μm produced by the inflation method of Shin-Etsu Film Co., Ltd. was used.

[0046] Next, in the same manner as in Example 1, using the mold shown in FIG. 2, Shin-Etsu Chemical's KMC-2280HT was molded under the same molding conditions with a compression molding device. The molded article was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0047] <Example 3> Substrate film: Polypropylene. A 70 μm-thick mirror-finished substrate film produced by Shin-Etsu Film Co., Ltd. using the inflation method was used.

[0048] A release layer having an average thickness of 1.0 μm was formed in the same manner as in Example 1, except that a release liquid was used in which Shin-Etsu Chemical's silicone release agent "KS-847H", Shin-Etsu Chemical's platinum catalyst "CAT PL-50T", and toluene as a solvent were mixed in a ratio of 100:1:350.

[0049] Next, similarly to Example 1, Shin-Etsu Chemical's KMC-2280HT was molded in a compression molding device under similar molding conditions using the mold shown in Fig. 2. The molded product after curing was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0050] <Example 4> Substrate film: Polypropylene A 50 μm thick matte surface substrate film produced by the inflation method of Shin-Etsu Film Co., Ltd. was used, but the preparation of a release film and molding were carried out in the same manner as in Example 1. The molded product after curing and molding was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0051] <Example 5> Substrate film: Polypropylene. A 40 μm thick matte surface substrate film produced by Shin-Etsu Film Co., Ltd. using the inflation method was used.

[0052] The release layer was made by mixing the silicone release agent "X-62-2829" manufactured by Shin-Etsu Chemical Co., Ltd., platinum catalyst "CAT PL-50T" manufactured by Shin-Etsu Chemical Co., Ltd., and toluene in a ratio of 100:1:450, as in Example 1, and applying the mixture to polypropylene using an applicator. The mixture was then dried and cured by heating at 150°C for 1 minute, forming a release layer with an average thickness of 1.0 μm.

[0053] Next, similarly to Example 1, Shin-Etsu Chemical's KMC-2280HT was molded in a compression molding device under similar molding conditions using the mold shown in Fig. 2. The molded product after curing was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0054] <Comparative Example 1> Substrate film: A PET film was used as the substrate film with a thickness of 50 μm, and the procedure was the same as in Example 1. The release layer was prepared by mixing the release liquid of Example 1, which was a mixture of Shin-Etsu Chemical's silicone release agent "X-62-2829", Shin-Etsu Chemical's platinum catalyst "CAT PL-50T", and toluene as a solvent in a ratio of 100:1:450 parts, using an applicator to apply the release liquid. The film was then dried and cured by heating at 120°C for 1 minute, to produce a release film having a release layer with an average thickness of 1.0 μm.

[0055] Next, similarly to Example 1, Shin-Etsu Chemical's KMC-2280HT was molded in a compression molding device under similar molding conditions using the mold shown in Fig. 2. The molded product after curing was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0056] <Comparative Example 2> Substrate film: A PET film was used as the substrate film with a thickness of 30 μm, and the procedure was the same as in Example 5. The release layer was prepared by mixing the release liquid of Example 1, which was a mixture of Shin-Etsu Chemical's silicone release agent "X-62-2829", Shin-Etsu Chemical's platinum catalyst "CAT PL-50T", and toluene as a solvent in a ratio of 100:1:450 parts, using an applicator to apply the liquid. The film was then dried and cured by heating at 150°C for 1 minute, to produce a release film having a release layer with an average thickness of 1.0 μm.

[0057] Next, similarly to Example 5, Shin-Etsu Chemical's KMC-2280HT was molded in a compression molding device under similar molding conditions using the mold shown in Figure 2. The molded product after curing was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0058] <Comparative Example 3> Using a commercially available ETFE (product name: Asahi Glass Aflex) 50 μm release film, Shin-Etsu Chemical KMC-2280HT was molded using a compression molding device with the mold shown in Figure 2. The mold temperature was 150°C, the molding pressure was 40 MPa, and the molding time was 5 minutes. The molded product after curing and molding was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0059] [Table 1]

[0060] As can be seen from Table 1, the release films for mold molding of the present invention using polypropylene (PP) as the base film in Examples 1 to 5 have excellent mold conformability and good releasability, and can produce products that maintain the mold accuracy in the molded shape. Furthermore, since it is polypropylene, there is no problem with disposal. On the other hand, Comparative Examples 1 and 2, which used PET as the base film, had low dimensional accuracy, and Comparative Example 3, which used a fluorine film, also had dimensional accuracy that was not as good as the release films for mold molding of the present invention, and also had disposal problems.

[0061] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0062] 1... mold forming release film, 11... base film, 12... release layer, 21...upper mold, 22...lower mold, 3...molded resin, 4...molded product.

Claims

1. A mold release film for mold forming, The release film for mold molding is composed of two layers: a base film having a thickness of 20 to 100 μm and a release layer having a thickness of 0.1 to 10 μm, and The base film is polypropylene, and A release film for mold molding, characterized in that the polypropylene is a polypropylene film formed by inflation molding.

2. The release film for mold molding according to claim 1, characterized in that the thermal elastic modulus of the polypropylene is 100 to 1000 MPa at 100°C, 20 to 300 MPa at 120°C, and 1 to 50 MPa at 150°C.

3. 3. The mold release film according to claim 1, wherein the release layer is made of a silicone resin.

4. The release film for mold molding according to any one of claims 1 to 3, characterized in that both sides of the polypropylene are treated to have a pear-shaped texture without embossing.

5. The release film for mold molding according to any one of claims 1 to 3, characterized in that both sides of the polypropylene are treated to have a mirror surface.

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