Release film for semiconductor resin molds

Abstract

To provide a release film which has an extremely low gas permeability, an enormously small mold contamination by a mold resin and a high releasability.A gas barrier release film for semiconductor resin molds, comprising a release layer (I) having excellent releasability, a plastic support layer (II) supporting the release layer, and a gas restraint layer (III) made of a metal or a metal oxide, formed between the release layer and the support layer, and having a xylene gas permeability of at most 10−15 (kmol m / (s·m2·kPa)) at 170° C. The release layer (I) is preferably formed from a fluororesin such as an ethylene / tetrafluoroethylene copolymer, and a metal oxide layer is preferably a layer of an oxide such as an aluminum oxide, a silicon oxide or a magnesium oxide.

Description

TECHNICAL FIELD[0001]The present invention relates to a release film for semiconductor resin molds, particularly a release film for semiconductor resin molds which can reduce mold contamination.BACKGROUND ART[0002]A semiconductor element (chip) is usually, for protection and blocking from an external environment (such as external air, contaminant, light, magnetism, high frequency wave or impulse), sealed with a resin (mold resin) and is mounted, on a substrate, in the form of a semiconductor package having the chip accommodated therein. Typically, the package is one formed by a transfer molding wherein a thermosetting resin (mold resin) such as an epoxy resin is melted by heating, and then, it is transferred in a mold where the semiconductor chip is set, followed by filling and curing. To the mold resin, a releasing agent is added in addition to a curing agent, a curing accelerator and a filler, to secure smooth releasability of the formed package from the mold.[0003]On the other ha...

AI Technical Summary

Benefits of technology

[0014]An object of the present invention is to provide a release film which is strongly demanded under the above circumstances, and which has extremely low gas permeability as compared with conventional ones and can substantially prevent mold contamination by a mold resin.

[0028]According to the present invention, a release film can be provided which has extremely low gas permeability as compared with conventional ones and can substantially prevent mold contamination by a mold resin. Further, a gas permeability required for the release film to effectively suppress the mold contamination, is defined by a gas permeability rate corresponding more realistically to a low viscosity material from a resin as a mold contaminant. Further, according to the present invention, a release film having a higher releasability from a mold resin can be provided. Further, the release film of the present invention is excellent in mold obsequence property.

Problems solved by technology

On the other hand, along with a strong demand for improvement of productivity of a semiconductor package, there is a problem such that since the resin adheres to the mold, the contaminated mold needs to be often cleaned, or when a sealing resin having a low shrinkage corresponding to a large package is used, sufficient releasability cannot be obtained even if a releasing agent is added.

As a result, in the step of molding a resin for the semiconductor element, the amount of gas and low viscosity material formed from the molten mold resin under a high temperature environment increases, and the gas and low viscosity material permeating through the above release film for molds contact the mold having a high temperature, whereby the mold contamination becomes intense.

Further, covering the mold surface with the release film is carried out by sucking and supporting the film thereon under vacuum, but a volatile component such as an oligomer in the film transfers to the covered side of the mold, whereby the mold contamination may sometimes be caused.

Thus, even though the release film is used in such a manner, the side of the mold covered with the film, tends to be easily contaminated.

Further, once the contamination is caused, the molding step for the semiconductor is required to be stopped for cleaning, and such leads to a problem such that the production efficiency of the semiconductor decreases.

However, such a metal deposited layer is one to be used by direct physical contact to the mold surface, and a metal powder tends to be released from the film surface or a broken section of the film, whereby its use for a molding step of the semiconductor resin is limited.

Further, in Patent Documents 1 and 2, the gas permeability of the release film is defined by a permeation of carbon dioxide gas, but such is not valid as an index for evaluating the permeability of a low viscosity material, etc. from a resin, etc.

Further, the release film is now required to have higher releasability from the mold resin, but such was not considered for the above release film, and the releasability was insufficient.

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