JP5431803B2 - Mold release seamless belt - Google Patents

Description

  The present invention relates to a mold release seamless belt. More specifically, the present invention relates to a mold release seamless belt that can be used for facilitating mold release of a semiconductor package or the like.

  A semiconductor package is generally manufactured by sealing a substrate on which a semiconductor chip is mounted with a sealing resin. Since such sealing is performed in the mold, a release sheet is generally disposed on the inner surface of the mold in order to improve the mold release property between the inner surface of the mold and the sealing resin.

  With the miniaturization of semiconductor packages, packaging is performed in a single-side sealed form typified by QFN. In packaging in such a single-side sealing form, a release sheet is disposed between the sealed surface of the substrate and the inner surface of the mold.

  In order to manufacture semiconductor packages continuously, recently, a reel device is arranged before and after the casting mold so that a roll-shaped release sheet can be conveyed, and a roll shape is formed after the sealing process is performed. There is known a method (reel-to-reel method) in which a release sheet is continuously fed and an unused release sheet is used in each sealing step (see Patent Document 1).

  However, in the manufacture of semiconductor packages by the reel-to-reel method, it is necessary to make the release sheet disposable in each sealing process, and it is necessary to send out unused sheets one after another with a margin. There is an economic problem that the loss is large.

  Further, in the manufacture of a semiconductor package by the reel-to-reel method, when a conventional release sheet is used, there is a problem that wrinkles are likely to occur when the mold is closed. Further, in the manufacture of a semiconductor package by the reel-to-reel method, when a conventional release sheet is used, there is a problem that the mold release property is inferior when the mold is opened.

JP 2005-123319 A

  An object of the present invention is a mold release member used when continuously manufacturing a semiconductor package or the like using a mold, which is excellent in continuous operability and economy, and has high adhesion when the mold is closed. An object of the present invention is to provide a release member having high durability, which can suppress generation of wrinkles and is excellent in release property when a mold is opened.

The mold release seamless belt of the present invention includes an inner layer containing a polyimide resin and an outer layer containing an elastomer.
In a preferred embodiment, the elastomer is at least one selected from a synthetic rubber and a thermoplastic elastomer.
In a preferred embodiment, the elastomer is silicone rubber.
In a preferred embodiment, the inner layer contains a heat conductive material, and the content ratio of the heat conductive material is 80% by weight or less based on the total weight of the inner layer.
In a preferred embodiment, a release layer is provided as an outer layer of the outer layer.
In a preferred embodiment, the release layer is a fluororesin layer containing a fluororesin.
In a preferred embodiment, the fluororesin is at least one selected from polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.
In a preferred embodiment, the fluororesin is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.
In a preferred embodiment, the volume resistivity of the entire seamless belt is a common logarithmic value of 4 to 13 (log Ω · cm).

  According to the present invention, it is a mold release member used for continuously manufacturing semiconductor packages and the like using a mold, which is excellent in continuous operability and economy, and has high adhesion when the mold is closed. It is possible to provide a release member having high durability that can suppress the generation of wrinkles and has excellent release properties when the mold is opened.

  As described above, a belt-like member different from a conventional sheet-like member is adopted as a release member used when continuously manufacturing a semiconductor package or the like using a mold. It can be expressed by adopting a mold release seamless belt having an inner layer containing a polyimide resin and an outer layer containing an elastomer.

It is a schematic sectional drawing of the mold release seamless belt (no release layer) in preferable embodiment of this invention. It is a schematic sectional drawing of the mold release seamless belt (with a mold release layer) in preferable embodiment of this invention. It is a schematic sectional drawing of an example of the preferable usage pattern of the mold release seamless belt of this invention.

A. Overall Configuration of Mold Release Seamless Belt The mold release seamless belt of the present invention is suitable as a release member used when a semiconductor package or the like is continuously manufactured using a mold. The mold release seamless belt of the present invention is particularly preferably a mold release member that is used by being disposed between the sealed surface of the substrate and the inner surface of the mold in packaging in a single-sided sealing form represented by QFN. It is suitable as.

  FIG. 1 is a schematic cross-sectional view of a mold release seamless belt (no release layer) according to a preferred embodiment of the present invention. The mold release seamless belt 100 includes an inner layer 1 and an outer layer 2. The inner layer 1 includes a polyimide resin. The outer layer 2 includes an elastomer. In this embodiment, the outer layer 2 is a layer forming the outer periphery of the mold release seamless belt, and is, for example, a layer on the side where a substrate on which a semiconductor chip is mounted or the like exists. Moreover, in this form, the inner layer 1 is a layer that forms the inner periphery of the mold release seamless belt, and is, for example, a layer that contacts the inner surface of the mold.

  FIG. 2 is a schematic cross-sectional view of a mold release seamless belt (with a release layer) according to a preferred embodiment of the present invention. The mold release seamless belt 100 includes an inner layer 1, an outer layer 2, and a release layer 3. The inner layer 1 includes a polyimide resin. The outer layer 2 includes an elastomer. In this embodiment, the release layer 3 is a layer that forms the outer periphery of the mold release seamless belt. For example, the release layer 3 is a layer on the side where a substrate on which a semiconductor chip is mounted is present. Moreover, in this form, the inner layer 1 is a layer that forms the inner periphery of the mold release seamless belt, and is, for example, a layer that contacts the inner surface of the mold.

  In the mold release seamless belt of the present invention, by adjusting the surface resistivity of the outermost layer, for example, it is possible to achieve both excellent adhesion to a substrate on which a semiconductor chip is mounted and excellent peelability. . Thereby, for example, the generation of wrinkles when the mold is closed can be effectively suppressed, and the releasability when the mold is opened can be improved. In a preferred embodiment, in the mold release seamless belt of the present invention, the surface resistivity of the outermost layer is a common logarithmic value of 4 to 13 (log Ω / □). The surface resistivity of the outermost layer can be controlled, for example, by containing a conductive substance in the outermost layer and adjusting the type and content of the conductive substance.

  In the mold release seamless belt of the present invention, any appropriate value can be adopted as the surface resistivity of the inner layer. In a preferred embodiment, the inner layer is adjusted in consideration of the adjustment value of the surface resistivity of the outermost layer so that the volume resistivity of the entire seamless belt of the present invention is 4 to 13 (log Ω · cm). What is necessary is just to control the surface resistivity.

  In a preferred embodiment, the volume resistivity of the entire mold release seamless belt of the present invention is a common logarithmic value of 4 to 13 (log Ω · cm). If the volume resistivity of the entire mold release seamless belt is in such a range, for example, it is possible to achieve both excellent adhesion to a substrate on which a semiconductor chip is mounted, an inner surface of a mold, etc. and excellent releasability. At the same time, fluctuations in the belt speed can be suppressed, and the uniformity of charge on the belt and exfoliation and discharge properties are excellent. The volume resistivity of the entire mold release seamless belt of the present invention can be controlled, for example, by adjusting the type and content of the conductive material that may be included in each layer.

  The mold release seamless belt of the present invention may further include any appropriate intermediate layer between the inner layer and the outer layer as long as the effect of the present invention is obtained. The inner layer may be provided with sprocket holes.

B. Inner layer In the mold release seamless belt of the present invention, the inner layer contains a polyimide resin. The content ratio of the polyimide resin in the resin constituting the inner layer is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, still more preferably 90 to 100% by weight, and more preferably 100% by weight. In the mold release seamless belt of the present invention, when the inner layer contains a polyimide resin, the mold release member has high durability. In addition, the mold release seamless belt of the present invention has the above inner layer containing polyimide resin and the specific outer layer in the present invention, so that the adhesiveness when the mold is closed is high and the generation of wrinkles can be suppressed. Excellent releasability when the mold is opened.

  Any appropriate resin can be adopted as the polyimide resin. Examples of the polyimide resin include a copolymer of tetracarboxylic dianhydride or a derivative thereof and a diamine compound.

  Specific examples of the tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,2′-bis (3,4 Dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ) Ete Dianhydride, ethylene tetracarboxylic dianhydride, and the like.

  Specific examples of the diamine compound include p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4 ′. -Diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, 2,4-bis (β-amino-t-butyl) Toluene, bis (p-β-amino-t-butylphenyl) ether Bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m- Xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylene Diamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethyl To heptamethylenediamine, 3-methyl Ptamethylenediamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12 -Diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and the like.

  The polyimide resin is preferably an aromatic polyimide resin. If an aromatic polyimide resin is used, it is possible to obtain a transport belt having better heat resistance and mechanical strength. Specific examples of the aromatic polyimide resin include a copolymer of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl ether (DDE), BPDA, and DDE. And a copolymer of p-phenylenediamine (PDA). The content ratio of the structural unit derived from PDA in the copolymer of BPDA, DDE and PDA is preferably 25 mol% or less with respect to the structural unit derived from DDE.

  In the mold release seamless belt of the present invention, the inner layer may contain a heat conductive material.

  Any appropriate material can be adopted as the heat conductive material. Specific examples of the heat conductive material include boron nitride, aluminum nitride, alumina, silicon carbide, silicon nitride, silica, and graphite. Boron nitride is preferred because it has high thermal conductivity, is stable, harmless, and easy to handle.

  In the inner layer, the content of the heat conductive material is preferably 10 to 80% by weight, more preferably 20 to 60% by weight, based on the polyimide resin. If the content rate of the said heat conductive substance is such a range, the mold release seamless belt excellent in heat conductivity can be obtained.

  In the mold release seamless belt of the present invention, the inner layer may contain a conductive substance.

  Any appropriate material can be adopted as the conductive material. Specific examples of the conductive material include various carbons such as carbon black; various metals such as aluminum, nickel, silver and copper; various inorganic compounds such as tin oxide and potassium titanate; and conductive materials such as polyaniline and polypyrrole. Polymer; and the like. Carbon black is preferred from the viewpoints of suppressing variations in surface resistance, realizing low cost, and being easy to handle.

Any appropriate carbon black may be adopted depending on the desired conductivity. Specific examples of the carbon black include channel black, furnace black, ketjen black, and acetylene black. When antistatic properties are required in the middle to high resistance range (for example, surface resistivity 10 ⁸ to 10 ¹⁴ Ω / □, volume resistivity 10 ⁸ to 10 ¹⁴ Ω · cm), channel black or furnace black Are preferably used. The carbon black may be subjected to a treatment such as an oxidation treatment or a graft treatment depending on the application. If oxidation treatment is performed, oxidative deterioration can be prevented, and if graft treatment is performed, dispersibility in a solvent can be improved.

  A commercial product may be used as the carbon black. As specific examples of commercially available channel black, trade names “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “Color Black FW1”, “Color Black FW18” manufactured by Degussa Huls, “Special Black 6”, “Color Black S170”, “Color Black S160”, “Special Black 5”, “Special Black 4”, “Special Black 4A”, “Printex 150T”, “Printex P” "Printex 140U", "Printex 140V", etc. are mentioned. As specific examples of commercially available furnace black, trade names “Special Black 550”, “Special Black 350”, “Special Black 250”, “Special Black 100”, “Printex 35”, and “Printex 35” manufactured by Degussa Huls. “25”, trade names “MA 7”, “MA 77”, “MA 8”, “MA 11”, “MA 100”, “MA 100R”, “MA 220”, “MA 230”, manufactured by Mitsubishi Chemical Corporation, “MONARCH 1300”, “MONARCH 1100”, “MONARCH 1000”, “MONARCH 900”, “MONARCH 880”, “MONARCH 800”, “MONARCH 700”, “MOGUL L”, “REG” manufactured by Cabot Corporation AL 400R "," VULCAN XC-72R "and the like.

  In the inner layer, the content ratio of the conductive substance is preferably 3 to 40% by weight, more preferably 3 to 30% by weight with respect to the polyimide resin. If the content rate of the said electroconductive substance is such a range, desired volume resistivity can be obtained about the whole mold release seamless belt of this invention. Moreover, it becomes possible to suppress peeling electrification by imparting semiconductivity to the inner layer.

  The thickness of the inner layer is preferably 5 to 500 μm, more preferably 10 to 300 μm, still more preferably 20 to 200 μm, and particularly preferably 50 to 100 μm from the viewpoint of excellent mechanical properties such as strength and flexibility. It is.

  The inner layer is prepared, for example, by (1) an organic solvent or a dispersion liquid by dispersing the thermally conductive substance or the conductive substance in an organic solvent, and (2) an organic solvent or a dispersion liquid. After the tetracarboxylic dianhydride or derivative thereof and the diamine compound are dissolved, a polymerization reaction is performed to prepare a polyamic acid solution. (3) After the polyamic acid solution is developed in a cylindrical mold, a ring-closing imide It can be obtained by making the reaction progress and forming the polyimide resin into a tubular shape.

  Any appropriate solvent can be adopted as the organic solvent. Specific examples of the organic solvent include acetone, chloroform, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, alcohol solvents (methanol, ethanol, isopropanol, etc.), N, N-dimethylformamide, N, N-dimethylacetamide, N, N. -Diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylenesulfone, dimethyltetramethylenesulfone, etc. . Of these, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, and N-methyl-2-pyrrolidone which are polar amide solvents are preferable. With these polar amide solvents, when a heat conductive material or a conductive material is used, a dispersion solvent for the heat conductive material or the conductive material can be used as a polymerization reaction solvent in a subsequent step. In addition, low molecular weight N, N-dimethylformamide and N, N-dimethylacetamide can be easily removed from the polyamic acid and the polyamic acid molded article by evaporation, substitution or diffusion. The said organic solvent may be used independently and may be used in combination of 2 or more type.

  In the organic solvent, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like may be mixed singly or in combination.

  A dispersant may be further added to the dispersion. If the dispersion contains a dispersant, the affinity between the heat conductive material or the conductive material and the organic solvent can be increased.

  Any appropriate dispersant can be adopted as the dispersant as long as the effects of the present invention can be obtained. Specific examples of the dispersant include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N N-vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline), etc. Polymer dispersing agent; surfactant; inorganic salt; and the like. These dispersants may be used alone or in combination of two or more.

  In the case of using the thermal conductive material or the conductive material, any appropriate dispersion method can be applied as a dispersion method of the thermal conductive material or the conductive material. Examples of the dispersion method include a ball mill, a sand mill, a basket mill, a three-roll mill, a planetary mixer, a bead mill, and an ultrasonic dispersion method. Any appropriate method can be applied as a method for examining the thermal conductive material and the dispersion state of the conductive material. For example, the method of observing with an optical microscope is mentioned.

  In obtaining the inner layer, a catalyst is preferably added when the tetracarboxylic dianhydride or its derivative and a diamine compound are subjected to a polymerization reaction. Any appropriate catalyst can be adopted as the catalyst. Specific examples of the catalyst include aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines. Of these, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, diethylpyridine, and β-picoline are preferable.

  The amount of the catalyst used is preferably 0.04 to 0.4 molar equivalent, more preferably 0.05 to 0.4 molar equivalent, relative to 1 molar equivalent of the amide acid in the polyamic acid precursor solution. If the addition amount of the catalyst is 0.04 equivalent mole or less, the effect of the catalyst may not be sufficient. Moreover, even if the addition amount of the catalyst is 0.4 equivalent or more, there is a possibility that the improvement effect of the catalyst addition is not seen.

  The monomer concentration (concentration of tetracarboxylic dianhydride component and diamine component in the solvent) during the polymerization reaction is preferably 5 to 30% by weight.

  The reaction temperature during the polymerization reaction is preferably 80 ° C. or lower, and more preferably 5 to 50 ° C. The reaction time is preferably 5 to 10 hours.

  The solution viscosity of the polyamic acid solution is preferably 1 to 1000 Pa · s (25 ° C.) with a B-type viscometer. If the solution viscosity is in such a range, the solution can be uniformly developed at the time of centrifugal molding in the next step, and a seamless belt having a uniform thickness can be obtained. The solution viscosity of the polyamic acid solution can be set to a desired viscosity by further heating and stirring the polyamic acid solution obtained after the polymerization reaction. The heating temperature is preferably 50 to 90 ° C.

  In obtaining the inner layer, preferably, the polyamic acid solution is developed in a cylindrical mold, and then the ring-closing imidization reaction is advanced to form a polyimide resin in a tubular shape. By molding the polyimide resin into a tubular shape, it is possible to obtain an inner layer of a seamless belt that does not have a joining portion (joining portion generated when the film is tubular). As a result, a seamless belt having excellent durability and circumference accuracy can be obtained. Examples of the method of developing in the cylindrical mold include a dispenser coating method, a dipping method, a centrifugal method, and a method of filling a casting mold. Preferably, a centrifugal method in which the inner peripheral surface of the mold is developed by a centrifugal force by a rotational centrifugal molding method is used. According to such a method, the polyamic acid solution can be uniformly developed. The ring-closing imidization reaction can proceed by heating the developed polyamic acid solution. The heating temperature at this time is preferably 300 to 400 ° C. The heating time at this time is preferably 0.5 to 1 hour. The heating method is preferably a method of heating while rotating the mold, a method of using high-precision hot air circulation, a method of charging at a low temperature to reduce the temperature rising rate, and a combination of these methods. According to such a heating method, the polyamic acid solution and the dried product can be uniformly heated. As a result, the volume resistivity of the entire mold release seamless belt of the present invention can be made uniform.

C. Intermediate Layer The mold release seamless belt of the present invention may have any appropriate intermediate layer between the inner layer and the outer layer as necessary. Examples of the intermediate layer include a conductive primer layer. If the conductive primer layer is provided as the intermediate layer, the adhesion between the outer layer and the inner layer can be improved. Examples of the conductive primer include a conductive fluorine-based primer and a conductive polyimide-based primer.

  The thickness of the intermediate layer is preferably 0.3 to 5 μm, more preferably 0.5 to 2 μm.

  The intermediate layer can be formed by any appropriate method. For example, when the intermediate layer is a conductive primer layer, it can be obtained by applying a primer solution to the outer peripheral surface of the inner layer. Examples of the application method include roll coating, brush coating, and spray coating.

D. Outer layer In the mold release seamless belt of the present invention, the outer layer contains an elastomer. The content of the elastomer in the resin constituting the outer layer is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, still more preferably 90 to 100% by weight, and more preferably 100% by weight. In the mold release seamless belt of the present invention, the outer layer contains an elastomer, so that the adhesion when the mold is closed is high and the generation of wrinkles can be suppressed, and the mold release characteristics when the mold is opened are excellent. . Moreover, the mold release seamless belt of the present invention is a release member having high durability because the outer layer contains an elastomer and has the specific inner layer in the present invention.

  Any appropriate elastomer can be adopted as the elastomer. As is generally known, an elastomer is a high-molecular substance exhibiting elasticity, and has a mechanical property (rubber elasticity) that is easily changed by an external force, but almost recovers to its original shape immediately after removing it.

  Examples of the elastomer include vulcanized rubber such as natural rubber and synthetic rubber; thermoplastic elastomer; elastic fiber such as spandex and polycarbonate elastic fiber; and elastic foam such as sponge rubber and foam rubber. In the present invention, it is preferable to employ at least one selected from synthetic rubber and thermoplastic elastomer as the elastomer.

  Examples of the synthetic rubber include styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), ethylene-propylene rubber (EPM, EPDM), and acrylonitrile-butadiene rubber (NBR). , Chloroprene rubber (CR), acrylic rubber (ACM, ANM), epichlorohydrin rubber (CO, ECO, GECO, GPCO), chlorinated polyethylene (CM), chlorosulfonated polyethylene (CSM), urethane rubber (U), fluoro rubber (FKM, FEPM, FFKM), silicone rubber (MQ, PMQ), polysulfide rubber (OT, EOT), phosphazene rubber (FZ, PZ) and the like.

  The thermoplastic elastomer is a polymer material that exhibits properties of vulcanized rubber at room temperature, is plasticized at high temperature, and can be molded by a plastic processing machine, and is referred to as TPE. Examples of the thermoplastic elastomer include polystyrene TPE, polyolefin TPE, polyester TPE, polyurethane TPE, 1,2-polybutadiene TPE, polyvinyl chloride TPE, polyamide TPE, and the like.

  In the present invention, the elastomer is more preferably an elastomer having tackiness. Examples of the elastomer having tackiness include fluorine rubber and silicone rubber.

  In the mold release seamless belt of the present invention, when the outer layer contains an elastomer, excellent mold adhesion and excellent mold release properties can be exhibited.

  In the mold release seamless belt of the present invention, the outer layer preferably contains a conductive substance. Any appropriate material can be adopted as the conductive material. Specific examples of the conductive material include those that can be used for the inner layer described above. Carbon black is preferred from the viewpoints of suppressing variations in surface resistance, realizing low cost, and being easy to handle.

  In the outer layer, the content of the conductive substance is preferably 30% by weight or less, more preferably 1 to 30% by weight, and still more preferably 5 to 25% by weight with respect to the total weight of the outer layer. If the content rate of the said electroconductive substance is such a range, a desired surface resistivity and volume resistivity can be obtained about the said outer layer and the whole mold release seamless belt of this invention.

  The thickness of the outer layer is preferably 5 to 700 μm, more preferably 10 to 500 μm, still more preferably 20 to 400 μm, and particularly preferably 50 to 300 μm from the viewpoint of excellent mechanical properties such as strength and flexibility. It is.

  When the outer layer is obtained, the outer layer is preferably formed by spreading the elastomer solution (elastomer solution) on the outer surface of the inner layer. The elastomer solution may be one in which the elastomer itself is in solution or may be one dissolved in the above organic solvent. By developing the elastomer solution on the outer surface of the inner layer, it is possible to obtain an outer layer of a seamless belt that does not have a joint (joint formed when the film is tubular). As a result, a seamless belt having excellent durability and circumference accuracy can be obtained. Examples of the developing method include a dispenser coating method, a dipping method, and a spray method.

  The method of spreading the elastomer solution on the outer surface of the inner layer preferably includes a step of applying the elastomer solution to the outer surface of the inner layer, and a step of drying and heating after the application.

  Examples of the method for applying the elastomer solution include spray coating, spin coating, roll coating, brush coating, and the like.

As the gun used for the spray coating, a gun having a small nozzle diameter is preferable because uniform application is possible. The nozzle diameter is preferably 0.1 to 2.0 mm. The spray pressure during the spray coating is preferably 1.0 to 5.0 kg / cm ² .

  When applying the elastomer solution, a cylinder for maintaining the shape may be inserted inside the inner layer. In addition, a cylindrical body is extrapolated to the inner layer to which the elastomer solution is applied, and from this state, the cylindrical body or the inner layer is caused to travel in the axial direction of the cylindrical body, or both are caused to travel in opposite directions. The coating thickness may be made uniform.

  The heating temperature after applying the elastomer solution is preferably 20 to 200 ° C, more preferably 80 to 150 ° C. The heating time during the heating is preferably 1 minute to 24 hours.

E. Release layer In the release seamless belt for molds of the present invention, a release layer may be provided as an outer layer of the outer layer.

  Any appropriate layer can be adopted as the release layer as long as the layer has releasability. The release layer is preferably a fluororesin layer containing a fluororesin because it has a high releasability and can sufficiently exhibit the effects of the present invention.

  Any appropriate fluororesin can be adopted as the fluororesin. Polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-perfluoro in that it has a higher releasability and can fully exhibit the effects of the present invention. It is preferably at least one selected from alkyl vinyl ether copolymers, more preferably tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers.

  A primer layer is preferably provided between the outer layer and the release layer in order to bond these two layers. Examples of the material for forming the primer layer include any appropriate primer such as PR-990CL (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.). A primer of fluorinated silicone such as PR-990CL is particularly preferred when these materials are used because, for example, silicone rubber and fluororesin can be more firmly bonded.

F. Form of Use of Mold Release Seamless Belt of the Present Invention The mold release seamless belt of the present invention can be used in any appropriate form. Preferably, it can be used for facilitating mold release when molding a semiconductor package or the like. More specifically, it is suitable as a mold release member used when a semiconductor package or the like is continuously manufactured using a mold, and the substrate is sealed in packaging in a single-sided sealing form represented by QFN. It is particularly suitable as a mold release member that is disposed between the surface and the inner surface of the mold.

  Unlike the roll-shaped release sheet used in the conventional reel-to-reel method, the mold release seamless belt of the present invention needs to be disposable for the part used as the release member in each sealing step. Absent. For this reason, the mold release seamless belt of this invention has a small loss in use, and can express high economical efficiency. Furthermore, the mold release seamless belt of the present invention has the specific configuration described above, so that the adhesiveness when the mold is closed is high and the generation of wrinkles can be suppressed, and when the mold is opened. Excellent releasability and high durability.

  The mold release seamless belt of the present invention is preferably used as a mold release member during continuous operation, in order to continuously operate the part used as the mold release member in each sealing step without being disposable. It is preferable to clean the part (used part). Any appropriate method can be adopted as the cleaning method. As the cleaning method, for example, a cleaning mechanism for cleaning the used part is provided in the mold apparatus (a continuous operation apparatus including a mold release seamless belt and a casting mold of the present invention). It is done. Examples of such a cleaning mechanism include a mechanism for cleaning by transfer using an adhesive roll, and a mechanism for cleaning by electrostatic attraction by reverse charging.

  The mold release seamless belt of the present invention may be passed through the upper mold side or the lower mold side when passing between the upper mold and the lower mold in the casting mold for manufacturing a semiconductor package. It may be passed through the side, or may be passed through both the upper mold side and the lower mold side.

  Since the mold release seamless belt of the present invention contains a polyimide resin in the inner layer, it has excellent durability, resistance to bending fatigue, and excellent heat resistance and dimensional stability. That is, the mold release seamless belt of the present invention can withstand continuous use under high temperature conditions, and does not get tired even when bent at an acute angle. For this reason, the mold release seamless belt of this invention can be used conveniently for semiconductor packaging, and can be used especially suitably for packaging by the single-side sealing form represented by QFN.

  An example of a preferable usage pattern of the mold release seamless belt of the present invention is shown in FIG. In FIG. 3, a substrate 10 on which a semiconductor chip is mounted is disposed between an upper mold 21 and a lower mold 22, and a mold release seamless belt 100 includes an upper mold 21 and a substrate 10 on which a semiconductor chip is mounted. It is arranged to pass between. The mold release seamless belt 100 is in contact with the cleaning mechanism 30 in an area outside the upper mold 21, and a part (used part) used as a release member in the mold release seamless belt 100 is used. Clean it. From the state of FIG. 3, the upper mold 21 and the lower mold 22 are closed and clamped, and the sealing resin is injected from the sealing resin injection port 40 of the lower mold 22 to be molded. The mold 22 is opened and the packaged molded product is taken out, and the mold release seamless belt 100 is sent out to prepare for the subsequent molding.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples. Unless otherwise specified, parts and% in the examples are based on weight (mass).

≪Volume resistivity≫
UP MCP-HT450 (manufactured by Mitsubishi Chemical Corporation, probe: UR) is used as the Hiresta, and the applied voltage is 500V. Under the measurement conditions for 10 seconds, the volume resistivity at 25 ° C. and 60% RH was measured. The measurement was performed at 12 points on the surface of the seamless belt, and the average value was shown as a common logarithmic value.

[Example 1]
Boron nitride was added to N-methylpyrrolidone (NMP) so as to be 40% by weight with respect to the solid content of the polyamic acid solution, and 3,3 ′, 4 was added as an acid component in the NMP solution dispersed for 12 hours by a ball mill. , 4′-biphenyltetracarboxylic dianhydride and a mixture of p-phenylenediamine and 4,4′-diaminodiphenyl ether (molar ratio 7: 3) as an amine component were prepared. Was dissolved in the NMP solution in the flask (monomer concentration 20% by weight), reacted at a temperature of 20 ° C. for 1 hour, and then heated at 75 ° C. for 10 hours to obtain a rotational viscosity of 220 Pa · s (with a B-type viscometer). Measurement: A polyamic acid solution (containing carbon black) having a measurement temperature of 25 ° C. was prepared. Then, it filtered using the # 800 stainless steel mesh, and was set as the polyamic-acid solution for tubular inner layer formation.

  Next, the polyamic acid solution was applied to the inner peripheral surface of a drum mold having an inner diameter of 200 mm and a length of 500 mm to a thickness of 400 μm via a dispenser, and rotated at 1500 rpm for 10 minutes to form a uniform thickness development layer. After that, while rotating at 250 rpm, hot air of 60 ° C. was blown from the outside of the drum mold for 30 minutes, and then heated at 150 ° C. for 60 minutes, and then heated to 350 ° C. at a rate of 2 ° C./minute. Heat for 30 minutes to remove the solvent, dehydrated ring-closing water and imide conversion, cool to room temperature and peel from the mold to obtain a polyimide resin tubular body with a thickness of 80 μm containing boron nitride It was.

  Conductive liquid silicone rubber (GE Toshiba Silicone Co., Ltd., XE16-B6430) is spray-coated on the outer peripheral surface of the polyimide resin tubular body thus obtained, and heated in a hot air circulation furnace at 150 ° C. for 30 minutes. Curing was performed to form an elastic body layer having a uniform thickness of 200 μm.

  Next, a primer (manufactured by Mitsui DuPont Fluoro Chemical Co., PR-990CL) is spray-coated on the elastic layer, and heated and dried in a 120 ° C. hot air circulation furnace for 10 minutes to form a primer layer having a thickness of 2 μm. did.

  Furthermore, PFA-dispersed paint (Mitsui DuPont Fluorochemicals, ENA-129-1) is spray-coated on the primer layer, and heated and dried in a 320 ° C hot air circulating furnace for 30 minutes to obtain a fluororesin having a thickness of 10 µm. A layer was formed.

  Thus, a mold release seamless belt (1) having a total thickness of 292 μm was obtained. The volume resistivity of the mold release seamless belt (1) was 10 (log Ω · cm) as a common logarithmic value.

  The obtained mold release seamless belt (1) was placed so that the inner layer of the belt rubs against the inner surface side of the upper mold as shown in FIG. On the other hand, on the outer layer side of the belt, a semiconductor chip mounted on a copper lead frame in which 4 × 4 16-pin QFNs are arranged on one side and wire-bonded with a gold wire is disposed. Next, the lower mold was closed so that the semiconductor chip was placed in the cavity of the lower mold.

  Next, the substrate on which the semiconductor chip was mounted was molded with a sealing resin under the following conditions. Using an epoxy-based sealing resin (manufactured by Nitto Denko Corporation: HC-300B type) and a molding machine (Model-Y-series manufactured by TOWA) at 175 ° C., preheating setting for 3 seconds, injection time of 12 seconds, curing time of 90 After molding in seconds, the mold was opened, and the molded product (sealed package) was taken out. Furthermore, the mold release seamless belt (1) was sent out by the amount used. As shown in FIG. 3, a cleaning mechanism is disposed in contact with a part of the mold release seamless belt (1).

  As described above, 100 shots of sealing resin were continuously applied.

  The molding surfaces of the obtained molded products were all smooth. From this, the adhesiveness between the inner surface of the mold when the mold is closed and the mold release seamless belt (1) is high, and the generation of wrinkles can be suppressed, and the mold when the mold is opened. It can be seen that the mold release seamless belt (1) has excellent mold release properties.

  Further, in the obtained molded product, no resin leakage was observed, and the casting success rate was 100%.

  Furthermore, when the mold release seamless belt (1) after continuously performing 100 shots of sealing resin was visually observed, no deterioration of the surface and no dimensional change were observed.

  The mold release seamless belt of the present invention can be suitably used for semiconductor packaging, and can be particularly suitably used for packaging in a single-side sealed form represented by QFN.

DESCRIPTION OF SYMBOLS 1 Inner layer 2 Outer layer 3 Release layer 10 Substrate 21 with semiconductor chip mounted Upper mold 22 Lower mold 30 Cleaning mechanism 40 Resin inlet 100 Mold release seamless belt

Claims (7)

A mold release member used when a semiconductor package is continuously manufactured using a mold,
E Bei an inner layer comprising a polyimide resin and an outer layer comprising an elastomer,
A release layer is provided as an outer layer of the outer layer,
The release layer is a fluororesin layer containing a fluororesin,
Release seamless belt for molds.   The mold release seamless belt according to claim 1, wherein the elastomer is at least one selected from a synthetic rubber and a thermoplastic elastomer.   The mold release seamless belt according to claim 2, wherein the elastomer is silicone rubber.   The mold release according to any one of claims 1 to 3, wherein the inner layer contains a heat conductive material, and a content ratio of the heat conductive material is 80 wt% or less with respect to a total weight of the inner layer. Seamless belt. The fluorine resin is polytetrafluoroethylene, tetrafluoroethylene - hexafluoropropylene copolymer, and tetrafluoroethylene - is at least one selected from perfluoroalkyl vinyl ether copolymer, any of claims 1 to 4 mold release seamless belt according to any. The mold release seamless belt according to claim 5 , wherein the fluororesin is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. The mold release seamless belt according to any one of claims 1 to 6 , wherein the volume resistivity of the entire seamless belt is a common logarithm of 4 to 13 (log Ω · cm).