Curable Resin Composition, Surface Protection Method, Temporary Fixation Method, and Separation Method

Abstract

To provide an environmentally-friendly curable resin composition for surface protection, having a high adhesive strength and being capable of forming a protective film which will readily be removed in the film form without adhesive residue in water on a member to be processed, a photocurable adhesive using it, a method for temporarily fixing a member, and a method for removing a protective film.

A curable resin composition for surface protection, comprising (A) a polyfunctional (meth)acrylate, (B) a monofunctional (meth)acrylate, and (C) a resin having a cyclopentadiene skeleton. Further, a curable resin composition for surface protection, comprising (A) a polyfunctional (meth)acrylate, (B) a monofunctional (meth)acrylate, (C) a resin having a cyclopentadiene skeleton, and (D) a photopolymerization initiator. Still further, a curable resin composition for surface protection, comprising (A) a polyfunctional (meth)acrylate, (B) a monofunctional (meth)acrylate, (C) a resin having a cyclopentadiene skeleton, (D) a photopolymerization initiator, and (E) a polar organic solvent.

Description

TECHNICAL FIELD[0001]The present invention relates to a surface protective film to protect a member to be processed in processing of various members from e.g. cutting wastes, and a surface protective film (hereinafter sometimes referred to as “protective film”) for temporary fixation to protect a portion which should not be painted or printed in painting or printing of a member to be processed with e.g. an ink. Further, it relates to a curable resin composition suitable for such a film and a method for protecting the surface of a member to be processed by using an adhesive comprising the curable resin composition.[0002]More specifically, the present invention relates to a method for removing a protective film covering a member in processing of members, and a photocurable adhesive suitable for such an application. Further, it relates to a method for temporarily fixing a member to be processed, which comprises bonding the member to be processed to a substrate, processing the member to...

AI Technical Summary

Benefits of technology

[0032]The method for removing a protective film of the present invention contributes to labor saving, energy saving and reduction in operation time as compared with a conventional hot-melt adhesive, since a protective film made of a curable resin composition is photocurable due to its composition, i.e. it is cured by active energy rays such as visible light or ultraviolet rays.

[0033]Further, the protective film made of the curable resin composition shows a high adhesive strength without being influenced by e.g. cutting water used at the time of processing, whereby it hardly causes displacement during processing of a component, and it is capable of protecting the component from infiltration of cutting water or from scars or contamination by e.g. cutting wastes. In addition, with respect to the removal of the protective film from the member to be processed after processing, by bonding a sheet to the surface of the member to be processed and / or the protective film, the removal is carried out easily without adhesive residue with excellent workability.

[0034]Further, when a protective film having a specific composition is used, by bringing the protective film into contact with warm water of at least 30° C., particularly warm water of at most 90° C., the adhesive strength will be lowered, and the bonding force between members or between a member and a jig will decrease, whereby the member will be readily recovered. Accordingly, it is not necessary to use an organic solvent which is expensive, which is highly flammable and which generates a gas harmful to the human body, as in the case of an adhesive used for a conventional surface protective film.

[0035]Further, the method is excellent in workability since the sheet used is a pressure-sensitive adhesive sheet comprising an adhesive layer formed on a substrate. Particularly in a case where the adhesive layer of the sheet is an adhesive curable with energy rays, the adhesive force will decrease by irradiation with energy rays. Further, since the protective film and the sheet covering the member to be processed are removed as combined, the member will be recovered without complexity.

[0036]Further, a curable resin composition having a specific preferred composition provides excellent workability since its cured product swells when brought into contact with warm water of at most 90° C., whereby it can be recovered in the form of a film from the member.

[0037]The curable resin composition for surface protection of the present invention contributes to labor saving, energy saving and reduction in operation time since it has a viscosity with which screen printing is applicable, in the preferred embodiments.

Problems solved by technology

However, in a case where a pressure-sensitive adhesive sheet is used as a protective film when a member to be processed is processed, along with downsizing and miniaturization of components in recent years, the bonding operation is complicated and in addition, even a slight displacement of the bonding position may impair the yield or the design properties of the products.

When a component has recesses and protrusions, the sheet cannot follow the recesses and protrusions and is removed during processing, thus contaminating the member to be processed in some cases.

In addition, when a pressure-sensitive adhesive sheet which has been cut to be fitted to the shape of the member to be processed is to be used, an expensive mold is required to cut the sheet, such being disadvantageous in view of cost.

However, since the method employs an aqueous alkali solution or an organic solvent, the cleaning process is complicated, and the method is problematic in view of working environment.

Further, in a case where the surface of a member to be processed has fine irregularities, the organic solvent cannot sufficiently infiltrate, whereby the protective film cannot completely be removed, thus causing problems in the outer appearance of the member to be processed.

Namely, a pressure-sensitive adhesive surface protective sheet presently used has limited capability to follow recesses and protrusions of a circuit on a semiconductor wafer.

The above phenomenon is not problematic when the thickness of the finished wafer is 150 μm or more, but when the wafer is thinner than 100 μm (particularly when the wafer is finished to have a thickness of 50 μm or below) or when protrusions on the wafer circuit surface such as bumps are remarkably high (for example, 100 μm or more), not only the deflective strength of the wafer will be remarkably lowered, but in a worse situation, the wafer may be even broken during grinding.

Further, when the wafer is ground to make it thin at a level of 50 μm, the cutout of the edge of the wafer or infiltration of the grinding water into a space between the wafer and the surface protective layer are problematic.

This is also due to insufficient adhesion of the surface protective sheet to the edge of the wafer.

Further, along with the tendency to make the wafer thin, on a semiconductor wafer which has, on the circuit surface, protrusions of 100 μm or higher represented by bumps, typical grinding itself carried out by bonding a semiconductor surface protective sheet is difficult.

However, if this tendency is too significant, a great stress will be applied to the wafer when the sheet is removed by peeling from the wafer, thus leading to breakage.

However, the adhesive layer is too soft if it is uncured at the time of grinding, whereby the wafer may be broken during grinding.

However, the adhesive, which is not a fluid, has insufficient capability to follow the recesses and protrusions on the wafer circuit surface.

However, this sheet is repeatedly melted every time the temperature exceeds the melting point.

Resultingly, such a defect may occur that the protective sheet is re-melted in some cases.

However, since an organic solvent is used, the cleaning step is complicated, and there is a problem in view of working environment.

Further, in the case of fine recesses and protrusions, the organic solvent cannot sufficiently infiltrate to completely remove the protective film, thus causing problems in the outer appearance of the member to be processed.