TWI859202B - Sheet for forming protective film and method for producing substrate device - Google Patents

Abstract

A protective film forming sheet, which has a substrate, an energy ray-curable adhesive layer on the substrate, and a curable protective film forming layer in sequence. The protective film forming layer is formed on the convex electrode forming surface of a workpiece having a convex electrode by being adhered to the convex electrode forming surface and cured. The shear storage modulus of the protective film forming layer at 23°C before curing is less than 3000MPa, and the tensile storage modulus of the adhesive layer after energy ray irradiation at 23°C is less than 45MPa.

Description

Sheet for forming protective film and method for producing substrate device

The present invention relates to a manufacturing method of a protective film forming sheet and a substrate device, and more particularly to a manufacturing method of a substrate device having a protective film forming sheet and a convex electrode, wherein the protective film forming sheet is suitable for protecting the convex electrode formed on the surface of a workpiece such as a semiconductor wafer and the workpiece.

In the past, when a multi-pin LSI package for an MPU or gate array is mounted on a printed wiring substrate, a printed chip mounting method is used. This printed chip mounting method uses a semiconductor chip having convex electrodes (bumps) formed on its connection pads with eutectic solder, high-temperature solder, gold, etc., and uses a so-called face-down method to make the bumps face and contact with the corresponding terminal parts on the chip mounting substrate, and perform melting/diffusion bonding.

The semiconductor chip used in this mounting method is obtained, for example, by grinding the surface of a semiconductor wafer on which bumps are formed on the surface of the electrical path, cutting and individualizing the semiconductor wafer. In the process of obtaining such a semiconductor chip, a curable resin film is usually attached to the bump-forming surface for the purpose of protecting the bumps and the surface of the electrical path of the semiconductor wafer, and the film is hardened to form a protective film on the bump-forming surface.

For example, Patent Document 1 discloses a film for forming a protective layer, wherein the melt viscosity of the thermosetting resin layer and the shear elastic modulus of the adhesive layer are within a specified range on a bump forming surface formed with a low dielectric material layer. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2015-92594

[The problem that the invention is trying to solve]

However, in the protective film forming film, the protective film forming layer is hardened in order to be easily peeled off from the adhesive layer. Therefore, when the protective film forming sheet is cut, there are problems such as cutting scraps caused by the protective film forming layer and the protective film forming layer is easily broken due to the bending of the protective film forming sheet during cutting.

As a result, the protective film becomes soft and becomes difficult to peel off from the adhesive layer.

The present invention was completed in view of such actual situation, and its purpose is to provide a protective film forming sheet having an adhesive layer that is easily peeled off from a protective film forming layer, and a method for manufacturing a substrate device having a convex electrode using the protective film forming sheet. [Means for solving the problem]

The present invention is as follows. [1] A protective film forming sheet, which comprises a substrate, an energy ray-curable adhesive layer on the substrate, and a curable protective film forming layer in order. The protective film forming layer is formed on the convex electrode forming surface of a workpiece having a convex electrode by being attached to the convex electrode forming surface and cured. The protective film forming layer before curing has a shear storage modulus of 3000 MPa or less at 23°C. The adhesive layer after energy ray irradiation has a tensile storage modulus of 45 MPa or less at 23°C.

[2] A protective film forming sheet, comprising, in order, a substrate, an adhesive layer on the substrate, and a curable protective film forming layer, wherein the protective film forming layer is formed on the convex electrode forming surface of a workpiece having a convex electrode by being adhered to the convex electrode forming surface and cured, and wherein the protective film forming layer before curing has a shear storage modulus of 3000 MPa or less at 23°C, and the adhesive layer has a tensile storage modulus of 45 MPa or less at 23°C.

[3] A protective film forming sheet as described in [1] or [2], wherein the adhesive layer has a reaction product, wherein an energy-ray-curable compound having an isocyanate group is added to an acrylic monomer having a hydroxyl group, and the content of the energy-ray-curable compound having an isocyanate group is 10% by mass or less relative to 100% by mass of the acrylic monomer having a hydroxyl group.

[4] The protective film-forming sheet according to any one of [1] to [3], comprising a buffer layer between the substrate and the adhesive layer.

[5] A method for manufacturing a substrate device, comprising the following steps: Attaching a protective film forming sheet having a substrate, an energy ray-curable adhesive layer on the substrate, and a curable protective film forming layer in sequence to a convex electrode forming surface of a workpiece having a convex electrode, so that the protective film forming layer is in contact with the convex electrode; Stripping the protective film forming layer before curing by energy ray irradiation The step of forming an adhesive layer after curing; The step of hardening the protective film forming layer to form a protective film; and The step of obtaining a workpiece processed by individualization from a workpiece having a convex electrode, The shear storage elastic modulus of the protective film forming layer before curing at 23°C is less than 3000MPa, The tensile storage elastic modulus of the adhesive layer after energy ray irradiation at 23°C is less than 45MPa.

[6] A method for manufacturing a substrate device, comprising the following steps: Attaching a protective film forming sheet having a substrate, an adhesive layer on the substrate, and a curable protective film forming layer in sequence to a convex electrode forming surface of a workpiece having a convex electrode, so that the protective film forming layer is in contact with the convex electrode; Stripping the adhesive from the protective film forming layer before curing The step of hardening the protective film forming layer to form a protective film; and The step of obtaining a workpiece processed by individualization from a workpiece having a convex electrode, The protective film forming layer before hardening has a shear storage modulus of 3000 MPa or less at 23°C, The adhesive layer has a tensile storage modulus of 45 MPa or less at 23°C. [Effect of the invention]

According to the present invention, a protective film forming sheet having an adhesive layer that can be easily peeled off from a protective film forming layer, and a method for manufacturing a substrate device having a convex electrode using the protective film forming sheet can be provided.

[Form for implementing the invention]

Hereinafter, the present invention will be described in detail based on specific implementation forms using the following sequence.

(1. Sheet for forming a protective film) As shown in FIG. 1A , the sheet for forming a protective film of the present embodiment has a structure in which an adhesive layer 20 and a protective film forming layer 30 are sequentially laminated on a substrate 10 .

In this embodiment, the protective film forming sheet is attached to a workpiece on which a convex electrode has been formed and used. For example, as shown in FIG2 , it is attached to a bump forming surface 101a of a semiconductor wafer with bumps, where bumps 102 as convex electrodes have been formed on a semiconductor wafer 101 as a workpiece. The bumps are formed in a manner electrically connected to a circuit already formed on the semiconductor wafer, so the bump forming surface 101a is an electrical surface.

After a semiconductor wafer with bumps to which a protective film forming sheet has been attached is subjected to a specified process (for example, grinding the back surface opposite to the surface on which the electric path is applied), the protective film forming layer is left on the bump forming surface while at least the protective film forming layer is in contact with the bumps, and the protective film forming sheet is peeled off.

The protective film forming layer expands between the bumps in a manner covering the bumps before and after peeling, and adheres to the electric road surface, covering at least the base of the bump and the electric road surface. If the protective film forming layer is cured, it further adheres to the electric road surface and the bump, forming a protective film that protects them. That is, the protective film forming layer and the protective film both protect the electric road surface and the bump. Therefore, after the protective film forming layer is formed on the bump forming surface, even if stress is applied to the bump, the bump crack can be effectively suppressed.

The semiconductor wafer with bumps and a protective film formed thereon is sliced into a plurality of semiconductor chips. At this time, each semiconductor chip has bumps and a protective film, and is mounted on a chip-carrying substrate in this state.

In this embodiment, the protective film forming sheet is not limited to the structure shown in FIG. 1A, and may have other layers as long as the effect of the present invention can be obtained. For example, as shown in FIG. 1B, a buffer layer 40 may be provided between the substrate and the adhesive layer. Although it will be described later, in the case where the height of the bump is high, the protective film forming sheet preferably has a buffer layer 40 as shown in FIG. 1B.

In this embodiment, in the protective film forming sheet, the components other than the protective film forming layer are sometimes referred to as a laminated sheet. For example, in the protective film forming sheet shown in FIG1A, the base material and the adhesive layer constitute the laminated sheet 50, and in the protective film forming sheet shown in FIG1B, the base material, the buffer layer and the adhesive layer constitute the laminated sheet 50. The components of the protective film forming sheet are described in detail below.

(2. Adhesive layer) The adhesive layer supports the protective film forming layer until the protective film forming layer is attached to the convex electrode forming surface and is peeled off from the protective film forming sheet. The adhesive layer may be composed of one layer (single layer) or may be composed of two or more layers. In the case where the adhesive layer has multiple layers, these multiple layers may be the same or different from each other, and the combination of layers constituting these multiple layers is not particularly limited.

The thickness of the adhesive layer is not particularly limited, but is preferably 1 μm to 100 μm, more preferably 3 μm to 50 μm, and even more preferably 5 μm to 30 μm. In addition, the thickness of the adhesive layer refers to the thickness of the adhesive layer as a whole. For example, the thickness of an adhesive layer composed of multiple layers refers to the total thickness of all layers constituting the adhesive layer.

In this embodiment, the adhesive layer has the following properties.

(2.1. Tensile storage modulus) In this embodiment, the tensile storage modulus of the adhesive layer at 23°C is 45 MPa or less. The tensile storage modulus is one of the indicators of the ease of deformation (hardness) of the adhesive layer. When the tensile storage modulus of the adhesive layer at 23°C is within the above range, it is difficult to cause hysteresis and slippage when the adhesive layer, i.e., the laminated sheet, is peeled off from the protective film forming layer, and the peeling property from the protective film forming layer becomes good. As a result, damage to the protective film formation layer can be suppressed, and the protruding electrodes of the substrate device can be fully protected when the protective film is formed.

The tensile storage modulus of the adhesive layer at 23°C is preferably 30 MPa or less, more preferably 20 MPa or less. The tensile storage modulus of the adhesive layer at 23°C is preferably 0.4 MPa or more, more preferably 2 MPa or more.

In addition, when the adhesive layer is energy-ray-curable, the above-mentioned tensile storage modulus is the tensile storage modulus of the adhesive layer after curing, that is, the tensile storage modulus of the adhesive layer after energy-ray irradiation.

(2.2. Adhesion) In this embodiment, the protective film forming layer is peeled off from the adhesive layer, so the adhesion of the adhesive layer at 23°C is the peeling force from the protective film forming layer. The adhesion is preferably 1500mN/25mm or less. When the adhesion of the adhesive layer is within the above range, the peeling property from the protective film forming layer becomes good.

The adhesive force of the adhesive layer at 23° C. is preferably 1200 mN/25 mm or less, more preferably 1000 mN/25 mm or less.

In addition, when the adhesive layer is energy-ray-curable, the above-mentioned adhesive force is the adhesive force of the adhesive layer after curing.

(2.3. Adhesive composition) The composition of the adhesive layer is not particularly limited as long as it has the above-mentioned physical properties, but in this embodiment, the adhesive layer is preferably composed of an adhesive composition having an adhesive resin.

Examples of the adhesive resin include acrylic resin (adhesive composed of a resin having a (meth)acryl group), urethane resin (adhesive composed of a resin having a urethane bond), rubber resin (adhesive composed of a resin having a rubber structure), silicone resin (adhesive composed of a resin having a siloxane bond), epoxy resin (adhesive composed of a resin having an epoxy group), polyvinyl ether, and polycarbonate. In the present embodiment, the adhesive resin is preferably an acrylic resin.

The adhesive composition may be an energy-ray-curable adhesive composition that can be cured by irradiation with energy rays, or may be a non-energy-ray-curable adhesive composition. In addition, as energy rays, ultraviolet rays, electron rays, etc. can be listed. In this embodiment, ultraviolet rays are preferred.

(2.3.1 Energy beam curable adhesive composition) When the adhesive composition is energy beam curable, the physical properties of the adhesive layer can be easily adjusted before and after curing.

Examples of energy-ray-hardening adhesive compositions include: an adhesive composition (1) comprising a non-energy-ray-hardening adhesive resin (1a) (hereinafter also referred to as "adhesive resin (1a)") and an energy-ray-hardening compound; and an adhesive composition (2) comprising an energy-ray-hardening adhesive resin (2a) (hereinafter also referred to as "adhesive resin (2a)") having an unsaturated group introduced into the side chain of the non-energy-ray-hardening adhesive resin (1a).

(2.3.1.1 Adhesive resin (1a)) The adhesive resin (1a) is preferably an acrylic resin. Examples of acrylic resins include acrylic polymers having at least a constituent unit derived from an alkyl (meth)acrylate. The constituent units of the acrylic polymer may be only one type or two or more types. In the case of two or more types, the combination and ratio thereof may be arbitrarily selected.

Examples of the (meth)acrylic acid alkyl ester include those having an alkyl group having 1 to 20 carbon atoms, and the alkyl group is preferably in a linear or branched chain form.

More specifically, the (meth)acrylate alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, ) isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (also known as lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (also known as myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (also known as palmityl (meth)acrylate), heptadecanyl (meth)acrylate, octadecyl (meth)acrylate (also known as stearyl (meth)acrylate), nonadecanyl (meth)acrylate, eicosyl (meth)acrylate, and the like.

From the viewpoint of improving the adhesive force of the adhesive layer, the acrylic polymer preferably has a constituent unit derived from an alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms. Furthermore, from the viewpoint of further improving the adhesive force of the adhesive layer, the alkyl group preferably has 4 to 12 carbon atoms, more preferably 8 to 12 carbon atoms. Furthermore, the alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms is preferably an alkyl acrylate.

The acrylic polymer preferably has a constituent unit derived from a monomer containing a functional group in addition to a constituent unit derived from an alkyl (meth)acrylate. Examples of the monomer containing a functional group include monomers that react with a crosslinking agent described below to form a crosslinking starting point, or monomers that react with an unsaturated group in an unsaturated group-containing compound to introduce an unsaturated group into the side chain of the acrylic polymer.

Examples of the functional group in the functional group-containing monomer include a hydroxyl group, a carboxyl group, an amino group, an epoxy group, etc. In the present embodiment, a hydroxyl group and a carboxyl group are preferred, and a hydroxyl group is more preferred.

Examples of the monomer containing a hydroxyl group include hydroxyalkyl (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and non-(meth)acrylic unsaturated alcohols (unsaturated alcohols having no (meth)acryloyl skeleton) such as vinyl alcohol and allyl alcohol.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids (monocarboxylic acids having an ethylenically unsaturated bond) such as (meth)acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids (dicarboxylic acids having an ethylenically unsaturated bond) such as fumaric acid, itaconic acid, citric acid, and citric acid; anhydrous products of ethylenically unsaturated dicarboxylic acids; (meth)acrylic acid carboxyl alkyl esters such as 2-carboxyethyl methacrylate, and the like.

The monomer containing a functional group constituting the acrylic polymer may be one kind or two or more kinds. When there are two or more kinds, the combination and ratio thereof may be arbitrarily selected.

In the acrylic polymer, the content of the constituent units derived from the monomers having a functional group is preferably 1 to 35 mass %, more preferably 3 to 32 mass %, and particularly preferably 5 to 30 mass % relative to the total mass of the constituent units.

In addition to the constituent units derived from (meth) alkyl acrylates and the constituent units derived from the monomers containing functional groups, acrylic polymers may further have constituent units derived from other monomers. Other monomers are not particularly limited as long as they can be copolymerized with (meth) alkyl acrylates, etc. Specifically, for example, styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, acrylamide, etc. can be listed. The other monomers may be only one or more. In the case of two or more, the combination and ratio thereof can be arbitrarily selected.

The adhesive resin (1a) may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected. In the adhesive composition (1), the content of the adhesive resin (1a) is preferably 5 to 99% by mass, more preferably 10 to 95% by mass, and particularly preferably 15 to 90% by mass, relative to the total mass of the adhesive composition (1).

(2.3.1.2 Energy-ray-hardening compound) The energy-ray-hardening compound contained in the adhesive composition (1) may be a monomer or oligomer having an energy-ray-polymerizable unsaturated group and being hardened by irradiation with energy rays.

Among the energy-ray-hardening compounds, as monomers, there can be cited, for example, polyvalent (meth)acrylates such as trihydroxymethylpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate; (meth)acrylate urethane; (meth)acrylate polyester; (meth)acrylate polyether ester; (meth)acrylate epoxy ester, etc.

Among the energy-ray-curable compounds, oligomers include, for example, oligomers obtained by polymerizing the monomers exemplified above.

The energy ray-hardening compound may be only one kind or two or more kinds. In the case of two or more kinds, their combination and ratio may be arbitrarily selected.

In the adhesive composition (1), the content of the energy radiation curable compound is preferably 1 to 95% by mass, more preferably 5 to 90% by mass, and particularly preferably 10 to 85% by mass, relative to the total mass of the adhesive composition (1).

(2.3.1.3 Adhesive resin (2a))

The adhesive composition (2) contains an energy-ray-curable adhesive resin (2a). In this embodiment, the adhesive resin (2a) is preferably an adhesive resin obtained by addition reaction of an acrylic polymer having a functional group and an energy-ray-curable compound having an energy-ray-curable group.

As the acrylic polymer having a functional group, a copolymer of an acrylic monomer having a functional group and an acrylic monomer having no functional group is preferred.

The acrylic monomer having a functional group is preferably a monomer containing a hydroxyl group or a monomer containing a carboxyl group, and more preferably a monomer containing a hydroxyl group.

Examples of the monomer containing a hydroxyl group include hydroxyalkyl (meth)acrylates such as hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and non-(meth)acrylic unsaturated alcohols (unsaturated alcohols having no (meth)acryloyl skeleton) such as vinyl alcohol and allyl alcohol.

In the present embodiment, the acrylic monomer having a functional group is preferably at least one selected from 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, and more preferably 2-hydroxyethyl (meth)acrylate.

Examples of acrylic monomers having no functional group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, propyl ... butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth)acrylate, butyl (meth The alkyl group constituting the alkyl esters such as isononyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (also called lauryl (meth)acrylate), tridecyl (meth)acrylate, tetradecyl (meth)acrylate (also called myristyl (meth)acrylate), pentadecyl (meth)acrylate, hexadecyl (meth)acrylate (also called palmityl (meth)acrylate), heptadecanyl (meth)acrylate, octadecyl (meth)acrylate (also called stearyl (meth)acrylate) is a chain structure alkyl (meth)acrylate having 1 to 18 carbon atoms.

In the present embodiment, from the viewpoint of the releasability from the protective film forming layer, a (meth)acrylic acid alkyl ester having an alkyl group with 4 to 12 carbon atoms is preferred, and a (meth)acrylic acid alkyl ester having an alkyl group with 8 to 12 carbon atoms is more preferred. Specifically, 2-ethylhexyl (meth)acrylate is preferred.

The energy-ray-curable compound having an energy-ray-curable group is preferably a compound having one or more selected from an isocyanate group, an epoxy group, and a carboxyl group, and more preferably a compound having an isocyanate group.

The energy-ray-hardening compound preferably has 1 to 5 energy-ray-hardening groups in one molecule, more preferably 1 to 2 energy-ray-hardening groups.

Examples of the energy beam curable compound include 2-methacryloyloxyethyl isocyanate, methyl-isoacryl-α,α-dimethylbenzyl isocyanate, methacryl isocyanate, allyl isocyanate, 1,1-(diacryloxymethyl)ethyl isocyanate; an acryl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; and an acryl monoisocyanate compound obtained by reacting a diisocyanate compound or a polyisocyanate compound, a polyol compound, and hydroxyethyl (meth)acrylate.

Among these, the energy ray-curable compound is preferably 2-methacryloyloxyethyl isocyanate.

When the energy-ray-curable compound is a compound having an isocyanate group, the isocyanate group reacts with the hydroxyl group of the acrylic polymer. The tensile storage modulus of the adhesive layer can be easily adjusted according to the degree of the addition reaction.

In the present embodiment, in the adhesive resin (2a), when the content of the monomer containing a hydroxyl group is set to 100 mass %, the content of the energy radiation curable compound having an isocyanate group is preferably 0.5 mass % or more and 10 mass % or less. By setting the content of the energy radiation curable compound to the above range, it becomes easy to set the tensile storage modulus of the adhesive layer after curing at 23° C. to the above range.

Furthermore, the adhesive composition (2) may contain an energy radiation-curable low molecular weight compound in addition to the adhesive resin (2a).

In this case, the content of the adhesive resin (2a) is preferably 5 to 99% by mass, more preferably 10 to 95% by mass, and particularly preferably 15 to 90% by mass, relative to the total mass of the adhesive composition (2).

As the energy-ray-curable low molecular weight compound, there can be mentioned monomers and oligomers having an energy-ray-polymerizable unsaturated group and being curable by irradiation with energy rays, and there can be mentioned the same energy-ray-curable compounds as those contained in the adhesive composition (1). The energy-ray-curable low molecular weight compound may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof can be arbitrarily selected.

(2.3.1.4 Crosslinking agent) When an acrylic polymer having a constituent unit derived from a monomer containing a functional group in addition to a constituent unit derived from an alkyl (meth)acrylate is used as the adhesive resin (1a) and the adhesive resin (2a), the adhesive composition (1) and the adhesive composition (2) preferably further contain a crosslinking agent.

The crosslinking agent is, for example, a substance that reacts with a functional group to crosslink the adhesive resin (1a) or the adhesive resins (2a) with each other.

Examples of crosslinking agents include tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, diisocyanate), such diisocyanate adducts (crosslinking agents having an isocyanate group); ethylene glycol epoxypropyl ether and other epoxy crosslinking agents (crosslinking agents having an epoxypropyl group); hexa[1-(2-methyl)-aziridinyl]-2,4,6-triphosphatriazine and other aziridine group crosslinking agents (crosslinking agents having an aziridine group); aluminum chelate and other metal chelate crosslinking agents (crosslinking agents having a metal chelate structure); isocyanurate crosslinking agents (crosslinking agents having an isocyanuric acid skeleton), etc.

The crosslinking agent is preferably an isocyanate crosslinking agent from the viewpoints of improving the cohesive force of the adhesive and thus improving the adhesive force of the adhesive layer and being easily available.

The crosslinking agent may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

In the adhesive composition (1) and the adhesive composition (2), the content of the crosslinking agent is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and particularly preferably 0.3 to 10 parts by mass, relative to 100 parts by mass of the adhesive resin (1a) or the adhesive resin (2a). By setting the content of the crosslinking agent within the above range, it becomes easy to set the tensile storage elastic modulus at 23° C. of the adhesive layer after curing within the above range.

(2.3.1.5 Photopolymerization initiator)

Adhesive composition (1) and adhesive composition (2) may further contain a photopolymerization initiator. Adhesive composition (1) and adhesive composition (2) containing a photopolymerization initiator will fully undergo a curing reaction even when irradiated with energy rays of relatively low energy such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin benzoic acid methyl ester, and benzoin dimethyl ketal; acetophenone compounds such as acetophenone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, and 2,2-dimethoxy-1,2-diphenylethane-1-one; acylphosphine oxide compounds such as bis(2,4,6-trimethylbenzyl)phenylphosphine oxide and 2,4,6-trimethylbenzyldiphenylphosphine oxide; benzylphenyl sulfide, tetramethylthiuram monosulfide, and the like. Sulfide compounds such as cyclohexyl phenyl ketone, α-keto alcohol compounds such as 1-hydroxycyclohexyl phenyl ketone, azo compounds such as azobisisobutyronitrile, titanium compounds such as titanium cyanide, thioxanthone compounds such as thioxanthone, peroxide compounds, diketone compounds such as diacetyl, benzil, bibenzyl, diphenyl ketone, 2,4-diethylthioxanthone, 1,2-diphenylmethane, oligomeric 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone, 2-chloroanthraquinone, etc.

In addition, as a photopolymerization initiator, quinone compounds such as 1-chloroanthraquinone, photosensitizers such as amines, etc. can also be used.

The photopolymerization initiator may be only one or two or more. In the case of two or more, the combination and ratio thereof may be arbitrarily selected.

In adhesive composition (1) and adhesive composition (2), the content of the photopolymerization initiator is preferably 0.01 to 20 parts by mass, more preferably 0.03 to 10 parts by mass, and particularly preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the energy ray-curable compound.

(2.3.1.6 Other additives)

The adhesive composition (1) and the adhesive composition (2) may contain other additives that are not included in any of the above-mentioned components within the range that does not impair the effects of the present invention.

As other additives, there can be listed well-known additives such as antistatic agents, antioxidants, softeners (plasticizers), fillers (fillers), rust inhibitors, colorants (pigments, dyes), sensitizers, adhesion promoters, reaction delay agents, crosslinking promoters (catalysts), etc.

The other additives may be one or more. In the case of two or more, the combination and ratio thereof may be arbitrarily selected. The content of the other additives in the adhesive composition (1) and the adhesive composition (2) is not particularly limited and may be appropriately selected according to the type of the other additives.

(2.3.2 Non-energy radiation curable adhesive composition) As non-energy radiation curable adhesive composition, for example, there can be cited adhesive resins such as acrylic resin (resin having (meth)acrylic group), urethane resin (resin having urethane bond), rubber resin (resin having rubber structure), silicone resin (resin having siloxane bond), epoxy resin (resin having epoxy group), polyvinyl ether, or polycarbonate, and preferably those containing acrylic resin.

The non-energy radiation-hardening adhesive composition preferably contains one or more crosslinking agents, and more preferably the type and content of the crosslinking agent are the same as those of the energy radiation-hardening adhesive composition.

(3. Protective film forming layer) The protective film forming layer is a sheet or film-like layer used to protect the convex electrodes protruding from the surface of the workpiece and the electric path formed on the workpiece, and is formed into a protective film by curing. The protective film forming layer can be composed of a single layer or a plurality of layers of two or more. In the case where the protective film forming layer has multiple layers, these multiple layers may be the same or different from each other, and the combination of layers constituting these multiple layers is not particularly limited.

The thickness of the protective film-forming layer is not particularly limited, but is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 80 μm or less, and still more preferably 5 μm or more and 60 μm or less. In addition, the thickness of the protective film-forming layer means the thickness of the entire protective film-forming layer. For example, the thickness of a protective film-forming layer composed of multiple layers means the total thickness of all layers constituting the protective film-forming layer.

In this embodiment, the protective film forming layer has the following physical properties.

(3.1. Shear storage modulus) In this embodiment, the shear storage modulus of the protective film forming layer at 23°C is 3000 MPa or less. The shear storage modulus is one of the indicators of the ease of deformation (hardness) of the adhesive layer. By making the shear storage modulus of the protective film forming layer at 23°C within the above range, the generation of cutting chips when cutting the protective film forming layer and the rupture of the protective film forming layer during cutting can be suppressed.

That is, in this embodiment, by setting both the tensile storage modulus of the adhesive layer and the shear storage modulus of the protective film forming layer within the above range, the peeling property of the adhesive layer from the protective film forming layer becomes good. In the case where at least one of them is outside the above range, the peeling property of the adhesive layer from the protective film forming layer is deteriorated.

The shear storage modulus of the protective film forming layer at 23°C is preferably 2750 MPa or less, more preferably 2000 MPa or less. The shear storage modulus of the protective film forming layer at 23°C is preferably 100 MPa or more, more preferably 500 MPa or more.

In addition, the protective film forming layer has curing properties, but the adhesive layer is peeled off before the protective film forming layer is cured, so the above-mentioned shear storage modulus is the shear storage modulus of the protective film forming layer before curing.

(3.2. Composition for protective film forming layer) As long as the protective film forming layer has the above-mentioned physical properties, the composition of the protective film forming layer is not particularly limited, but in this embodiment, the protective film forming layer is preferably composed of a protective film forming layer composition having curability.

In the present embodiment, the protective film forming layer composition is not particularly limited as long as it has curability, but it is preferably at least thermosetting.

(3.2.1 Composition for thermosetting protective film forming layer) As the composition for thermosetting protective film forming layer, for example, there can be cited a composition for protective film forming layer (1) containing a polymer component (A) and a thermosetting component (B). The polymer component (A) can be regarded as a component formed by a polymerization reaction of a polymerizable compound. In addition, the thermosetting component (B) is a component that can undergo a curing (polymerization) reaction. In addition, in the present invention, the polymerization reaction also includes a polycondensation reaction.

(3.2.1.1 Polymer component (A)) The polymer component (A) is a polymer compound used to impart film-forming properties and flexibility to the protective film-forming layer. The polymer component (A) contained in the protective film-forming layer composition (1) may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

The polymer component (A) is preferably a thermoplastic resin. The use of a thermoplastic resin has the following advantages: the peeling property of the protective film forming layer from the laminated sheet (adhesive layer) is improved, the protective film forming layer becomes easier to follow the uneven surface of the adherend, and the occurrence of gaps between the adherend and the thermoplastic resin layer can be further suppressed.

As the thermoplastic resin, for example, polyvinyl acetal, acrylic resin, polyester, polyurethane, phenoxy resin, polybutene, polybutadiene, polystyrene can be listed. In the present embodiment, polyvinyl acetal is preferred.

The weight average molecular weight of the thermoplastic resin is preferably 5000 to 200000, more preferably 8000 to 100000. The glass transition temperature (Tg) of the thermoplastic resin is preferably 40 to 80°C, more preferably 50 to 70°C.

The thermoplastic resin contained in the protective film forming layer composition (1) may be only one kind or two or more kinds. When it is two or more kinds, the combination and ratio thereof may be arbitrarily selected.

In the protective film forming layer composition (1), regardless of the type of the polymer component (A), the content ratio of the polymer component (A) relative to the total content of all components (i.e., the content of the polymer component (A) in the protective film forming layer) is preferably 5 to 85% by mass, more preferably 5 to 80% by mass.

The polymer component (A) may also be a thermosetting component (B). In the present invention, when the protective film forming layer composition (1) contains components belonging to both such a polymer component (A) and a thermosetting component (B), the protective film forming layer composition (1) is regarded as containing the polymer component (A) and the thermosetting component (B).

(3.2.1.2 Thermosetting component (B)) The composition (1) for the protective film forming layer contains a thermosetting component (B). Since the protective film forming layer contains the thermosetting component (B), the thermosetting component (B) cures the protective film forming layer by heating to form a hard protective film.

The thermosetting component (B) may be one kind or two or more kinds. When two or more kinds are used, the combination and ratio thereof may be arbitrarily selected.

Examples of the thermosetting component (B) include epoxy-based thermosetting resins, thermosetting polyimide, polyurethane, unsaturated polyester, and polysilicone resins. In this embodiment, epoxy-based thermosetting resins are preferred.

The epoxy-based thermosetting resin contained in the protective film forming layer composition (1) may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected. The epoxy-based thermosetting resin is composed of an epoxy resin (B1) and a thermosetting agent (B2).

Examples of the epoxy resin (B1) include known epoxy resins such as polyfunctional epoxy resins, biphenyl compounds, bisphenol A diglycidyl ether and its hydrogenated product, o-cresol novolac epoxy resin, biscyclopentadiene epoxy resin, biphenyl epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, phenylene skeleton epoxy resin, and epoxy compounds having two or more functional groups. Among them, polyfunctional epoxy resins, biscyclopentadiene epoxy resins, bisphenol F epoxy resins, and the like are preferred.

As the epoxy resin (B1), an epoxy resin having an unsaturated hydrocarbon group can be used. An epoxy resin having an unsaturated hydrocarbon group has higher compatibility with an acrylic resin than an epoxy resin having no unsaturated hydrocarbon group. Therefore, by using an epoxy resin having an unsaturated hydrocarbon group, the reliability of a package obtained using the protective film forming sheet is improved.

Examples of epoxy resins having an unsaturated hydrocarbon group include compounds in which a portion of the epoxy groups of a polyfunctional epoxy resin is converted into a group having an unsaturated hydrocarbon group. Such compounds can be obtained, for example, by subjecting an epoxy group to an addition reaction with (meth)acrylic acid or a derivative thereof.

Examples of the epoxy resin having an unsaturated hydrocarbon group include compounds in which an aromatic ring constituting the epoxy resin is directly bonded to a group having an unsaturated hydrocarbon group.

The unsaturated hydrocarbon group is a polymerizable unsaturated group, and specific examples thereof include vinyl (ethenyl) group (vinyl), 2-propenyl (allyl), (meth)acrylyl, (meth)acrylamide, etc., preferably acrylyl group.

The number average molecular weight of the epoxy resin (B1) is not particularly limited, but is preferably 300 to 30,000, more preferably 400 to 10,000, and particularly preferably 500 to 3,000 from the viewpoint of the curability of the protective film-forming layer and the strength and heat resistance of the protective film after curing.

The epoxy equivalent of the epoxy resin (B1) is preferably 100 to 1000 g/eq, more preferably 300 to 800 g/eq.

The epoxy resin (B1) may be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio thereof may be arbitrarily selected.

The thermosetting agent (B2) functions as a hardener for the epoxy resin (B1).

As the heat curing agent (B2), for example, there can be mentioned compounds having two or more functional groups capable of reacting with epoxy groups in one molecule. As the functional group, for example, there can be mentioned phenolic hydroxyl groups, alcoholic hydroxyl groups, amino groups, carboxyl groups, acid groups anhydrided groups, etc., preferably phenolic hydroxyl groups, amino groups, or acid groups anhydrided groups, more preferably phenolic hydroxyl groups or amino groups.

Among the thermosetting agents (B2), examples of phenolic curing agents having a phenolic hydroxyl group include polyfunctional phenol resins, biphenol, novolac-type phenol resins, dicyclopentadiene-type phenol resins, and aralkylphenol resins.

Among the heat curing agents (B2), examples of amine-based curing agents having an amine group include dicyandiamide (hereinafter sometimes abbreviated to "DICY") and the like.

The thermosetting agent (B2) may be one having an unsaturated hydrocarbon group. Examples of the thermosetting agent (B2) having an unsaturated hydrocarbon group include a compound in which a part of the hydroxyl group of a phenol resin is substituted with a group having an unsaturated hydrocarbon group, and a compound in which an aromatic ring of a phenol resin is directly bonded to a group having an unsaturated hydrocarbon group.

The unsaturated hydrocarbon group in the thermosetting agent (B2) is the same as the unsaturated hydrocarbon group in the above-mentioned epoxy resin having an unsaturated hydrocarbon group.

When a phenolic curing agent is used as the thermosetting agent (B2), the thermosetting agent (B2) preferably has a high softening point or glass transition temperature because the peeling property of the protective film-forming layer from the adhesive layer is improved.

The number average molecular weight of the resin component of the thermosetting agent (B2), such as a polyfunctional phenol resin, a novolac phenol resin, a dicyclopentadiene phenol resin, an aralkylphenol resin, etc., is preferably 300 to 30,000, more preferably 400 to 10,000, and particularly preferably 500 to 3,000.

The molecular weight of non-resin components such as diphenol and dicyandiamide in the thermosetting agent (B2) is not particularly limited, but is preferably 60 to 500, for example.

As the thermosetting agent (B2), for example, novolac type phenol resin is preferred.

The thermosetting agent (B2) may be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio thereof may be arbitrarily selected.

In the composition (1) for forming a protective film, the content of the thermosetting agent (B2) is preferably 0.1 to 500 parts by mass, more preferably 1 to 200 parts by mass, relative to 100 parts by mass of the epoxy resin (B1). When the content of the thermosetting agent (B2) is equal to or greater than the lower limit, the curing of the protective film forming layer is more easily performed. When the content of the thermosetting agent (B2) is equal to or less than the upper limit, the moisture absorption rate of the protective film forming layer is reduced, and the reliability of the package obtained by using the protective film forming sheet is further improved.

In the protective film forming layer composition (1), the content of the thermosetting component (B) (for example, the total content of the epoxy resin (B1) and the thermosetting agent (B2)) is preferably 50 to 1000 parts by mass, more preferably 100 to 900 parts by mass, and particularly preferably 150 to 800 parts by mass relative to 100 parts by mass of the polymer component (A). By setting the content ratio of the thermosetting component (B) within the above range, it becomes easy to set the shear storage modulus of the protective film forming layer at 23°C before curing within the above range. Furthermore, the releasability of the adhesive layer is improved.

(3.2.1.3 Hardening accelerator (C))

The protective film forming layer composition (1) may contain a hardening accelerator (C). The hardening accelerator (C) is a component for adjusting the hardening speed of the protective film forming layer composition (1).

Preferred hardening accelerators (C) include tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris(dimethylaminomethyl)phenol; imidazoles (imidazoles in which one or more hydrogen atoms are replaced by groups other than hydrogen atoms) such as 2-methylimidazole, 2-benzimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; organic phosphines (phosphines in which one or more hydrogen atoms are replaced by organic groups) such as tributylphosphine, diphenylphosphine, and triphenylphosphine; tetraphenylborates such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate, among which 2-phenyl-4,5-dihydroxymethylimidazole is preferred.

The curing accelerator (C) contained in the protective film forming layer composition (1) may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

When a hardening accelerator (C) is used, the content of the hardening accelerator (C) is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the content of the thermosetting component (B) in the protective film forming layer composition (1). When the content of the hardening accelerator (C) is above the lower limit, the effect of using the hardening accelerator (C) can be more significant. In addition, when the content of the hardening accelerator (C) is below the upper limit, for example, the effect of suppressing the high-polarity hardening accelerator (C) from moving to the interface side with the adherend in the protective film forming layer under high temperature and high humidity conditions and segregating becomes higher, and the reliability of the package obtained using the protective film forming sheet is further improved.

(3.2.1.4 Filler (D)) The protective film forming layer composition (1) may contain a filler (D). By adjusting the content of the filler (D) in the curable protective film forming layer, the wettability and spreadability of the curable protective film forming layer can be adjusted. That is, by increasing the content of the filler (D), the wettability and spreadability can be reduced, and by reducing the content of the filler (D), the wettability and spreadability can be increased. In addition, by containing the filler (D) in the protective film forming layer, it becomes easier to adjust the thermal expansion coefficient of the protective film obtained by curing the protective film forming layer, and by optimizing this thermal expansion coefficient for the object of forming the protective film, the reliability of the package obtained using the protective film forming sheet can be further improved. Furthermore, by including the filler (D) in the protective film forming layer, the moisture absorption rate of the protective film can be reduced.

The filler (D) may be either an organic filler or an inorganic filler, but is preferably an inorganic filler.

Preferred inorganic fillers include powders of silica, alumina, talc, calcium carbonate, titanium dioxide, red lead, silicon carbide, boron nitride, etc.; beads obtained by sphericalizing these inorganic fillers; surface-modified products of these inorganic fillers; single crystal fibers of these inorganic fillers; glass fibers, etc.

Among these, the inorganic filler is preferably silica, alumina or surface-modified silica. More specifically, spherical silica modified with epoxy groups can be cited. In addition, the average particle size of the inorganic filler is preferably 5nm to 800nm, more preferably 10nm to 300nm, further preferably 30nm to 100nm, and particularly preferably 40nm to 60nm.

(3.2.1.5 Other additives) The protective film forming layer composition (1) may contain other additives such as energy radiation curable resin, photopolymerization initiator, coupling agent, crosslinking agent, plasticizer, antistatic agent, antioxidant, coloring agent (dyes, pigments), gettering agent, etc., within the scope that does not impair the effects of the present invention.

(3.2.2 Composition for forming a protective film having a radiation-hardening property) As the composition for forming a protective film having a radiation-hardening property, for example, there can be mentioned a composition for forming a protective film having a radiation-hardening property containing a radiation-hardening property. The radiation-hardening property is preferably unhardened, preferably has adhesiveness, and more preferably is unhardened and has adhesiveness.

The energy radiation curable component is a component that is cured by irradiation with energy radiation, and is also a component for imparting film-forming properties, flexibility, etc. to the protective film-forming layer.

As the energy-ray-hardening component, for example, a polymer or compound having an energy-ray-hardening group is preferred. As such a polymer or compound, well-known ones can be cited. For example, the polymer or compound having an energy-ray-hardening group exemplified in the above-mentioned adhesive composition can be cited.

(4. Buffer layer) As described above, the protective film forming sheet of this embodiment is also preferably configured as shown in FIG. 1B. That is, a buffer layer can be arranged between the substrate and the adhesive layer. In particular, when the height of the convex electrode is high, the convex electrode passing through the protective film forming layer and the adhesive layer is embedded in the buffer layer, thereby fully protecting the convex electrode.

The buffer layer may be a single layer or may be a plurality of layers of two or more. In the case of a plurality of layers, the plurality of layers may be the same as or different from each other, and the combination of the plurality of layers is not particularly limited.

The thickness of the buffer layer can be appropriately adjusted according to the height of the convex electrode on the surface of the semiconductor wafer to be protected, but from the point of view of easily absorbing the influence of the convex electrode with a higher height, the preferred thickness is 50 to 600 μm, more preferably 100 to 500 μm, and particularly preferably 150 to 450 μm.

Here, the thickness of the buffer layer refers to the thickness of the entire buffer layer. For example, the thickness of a buffer layer composed of multiple layers refers to the total thickness of all layers constituting the buffer layer.

(4.1. Composition for forming a buffer layer) The composition of the buffer layer is not particularly limited as long as the buffer layer is formed in a manner that can absorb the influence of the convex electrode. However, in this embodiment, the buffer layer is preferably formed of the composition for forming a buffer layer shown below.

Examples of the buffer layer forming composition include a buffer layer forming composition containing poly-α-olefin and a buffer layer forming composition containing urethane (meth)acrylate.

The buffer layer-forming composition containing poly-α-olefin may contain components other than poly-α-olefin within a range not impairing the effects of the present invention.

The poly-α-olefin may be any one as long as it has a constituent unit derived from α-olefin. The constituent units of the poly-α-olefin may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected. That is, the poly-α-olefin may be a homopolymer formed by polymerizing one kind of monomer or a copolymer formed by copolymerizing two or more kinds of monomers.

In this embodiment, the poly-α-olefin is preferably an ethylene-α-olefin copolymer.

The density of the poly-α-olefin is preferably 890 kg/m ³ or less, more preferably 830 to 890 kg/m ³ , and particularly preferably 850 to 875 kg/m ³ . The melting point of the poly-α-olefin is preferably 55° C. or less, more preferably 50° C. or less. The melt flow rate (MFR) of the poly-α-olefin at 190° C. is preferably 1 to 6 g/10 min, more preferably 2.5 to 4.5 g/10 min.

The content of the poly-α-olefin in the buffer layer forming composition is preferably 80 to 100% by mass.

The buffer layer-forming composition containing (meth) urethane acrylate may contain components other than (meth) urethane acrylate, for example, a polymerizable monomer, a photopolymerization initiator, etc., within the range not impairing the effects of the present invention.

Urethane (meth)acrylate is a compound having at least a (meth)acryl group and a urethane bond in one molecule and has energy ray polymerizability. Urethane (meth)acrylate may be monofunctional or polyfunctional, but preferably is at least monofunctional.

Furthermore, the (meth)acrylic acid urethane may be any of an oligomer, a polymer, and a mixture of an oligomer and a polymer, but is preferably an oligomer. Furthermore, the (meth)acrylic acid urethane may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

The weight average molecular weight of the urethane (meth)acrylate is preferably 1,000 to 100,000, more preferably 3,000 to 80,000, particularly preferably 5,000 to 65,000.

In the present embodiment, the (meth)acrylic urethane may be, for example, a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyvalent isocyanate compound, and a (meth)acrylic compound having a hydroxyl group and a (meth)acryl group. Here, the "terminal isocyanate urethane prepolymer" means a prepolymer having a urethane bond and an isocyanate group at the terminal of the molecule.

As the polyol compound, there can be cited, for example, alkylene glycol, polyether polyol, polyester polyol, polycarbonate polyol, etc. In the present embodiment, polyether polyol is preferred, and polyether diol is more preferred.

The polyvalent isocyanate compound is not particularly limited as long as it has two or more isocyanate groups. In the present embodiment, isophorone diisocyanate, hexamethylene diisocyanate or xylene diisocyanate is preferred.

The (meth)acrylic acid compound is not particularly limited as long as it is a compound having at least a hydroxyl group and a (meth)acryl group in one molecule. In the present embodiment, a (meth)acrylate containing a hydroxyl group is preferred, a (meth)acrylate alkyl containing a hydroxyl group is more preferred, and 2-hydroxyethyl (meth)acrylate is particularly preferred.

(5. Substrate) The substrate 10 of the protective film forming sheet 1 of this embodiment is not particularly limited as long as it is configured in a manner that supports an adhesive layer and a protective film forming layer and can form a protective film on the surface of the workpiece having a convex electrode. In this embodiment, for example, various resin films used as substrates for wafer polishing tapes can be used.

Specifically, polyethylenes such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE) can be cited; polyolefins other than polyethylenes such as polypropylene, polybutene, polybutadiene, polymethylpentene, and norbornene resins; ethylene-vinyl acetate copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylate copolymers, and ethylene-norbornene copolymers (copolymers obtained using ethylene as a monomer); vinyl chloride-based resins (resins obtained using vinyl chloride as a monomer) such as polyvinyl chloride and vinyl chloride copolymers; polystyrene; polycycloolefins; polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; Polyesters such as polyethylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalene dicarboxylate, and wholly aromatic polyesters in which all constituent units have aromatic cyclic groups; copolymers of two or more polyesters; poly(meth)acrylates; polyurethanes; polyurethane acrylates; polyimides; polyamides; polycarbonates; fluororesins; polyacetals; modified polyphenylene oxides; polyphenylene sulfide; polysulfones; and polyether ketones.

In addition, polymer alloys such as a mixture of polyester and other resins can also be cited. The polymer alloy of polyester and other resins is preferably one in which the amount of the other resin is relatively small.

In addition, there can be mentioned crosslinked resins in which one or more of the above resins are crosslinked; and modified resins such as ionic polymers using one or more of the above resins.

The resin constituting the substrate may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof may be arbitrarily selected.

The substrate may be a single layer or may be a plurality of layers of two or more. In the case of a plurality of layers, the plurality of layers may be the same as or different from each other, and the combination of the plurality of layers is not particularly limited.

The thickness of the substrate is preferably 50 to 200 μm. Here, the thickness of the substrate refers to the thickness of the entire substrate. For example, the thickness of a substrate composed of multiple layers refers to the total thickness of all layers constituting the substrate.

The substrate preferably has a high thickness accuracy, that is, a substrate with suppressed thickness variation regardless of the location. Among the above-mentioned constituent materials, materials that can be used to constitute such a substrate with a high thickness accuracy include polyethylene, polyolefins other than polyethylene, polyethylene terephthalate, and ethylene-vinyl acetate copolymer.

In addition to the main constituent materials such as resin, the base material may also contain various well-known additives such as fillers, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, softeners (plasticizers), etc.

The substrate may be transparent or opaque, may be colored according to the purpose, or may be deposited with other layers. When the adhesive layer or protective film forming layer is energy-ray-curable, the substrate is preferably energy-ray-transmissive.

The substrate can be manufactured by a known method. For example, the resin-containing substrate 10 can be manufactured by molding a resin composition containing a resin.

(6. Adhesion layer) In this embodiment, in order to improve the adhesion between the substrate and the buffer layer, an adhesion layer can be provided between the substrate and the buffer layer.

As a material constituting the adhesive layer, for example, ethylene-vinyl acetate copolymer is exemplified. The thickness of the adhesive layer is preferably 10 to 100 μm.

(7. Method for manufacturing protective film forming sheet) The method for manufacturing the protective film forming sheet of this embodiment is not particularly limited as long as it is a method that can form a sheet by laminating an adhesive layer and a protective film forming layer on one side of a substrate, and any well-known method may be used.

First, as a composition for forming an adhesive layer, for example, an adhesive composition containing the above-mentioned components or a composition obtained by diluting the adhesive composition with a solvent etc. is prepared. Similarly, as a composition for forming a protective film forming layer, for example, a protective film forming layer composition containing the above-mentioned components or a composition obtained by diluting the protective film forming layer with a solvent etc. is prepared. In the case where the protective film forming sheet has a buffer layer, it is sufficient to prepare a buffer layer forming composition.

Examples of the solvent include organic solvents such as methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol.

Then, the adhesive composition is applied to the substrate by a known method such as a rotary coating method, a spray coating method, a rod coating method, a doctor blade coating method, a roll coating method, a doctor blade coating method, a die coating method, a gravure coating method, etc., and heated to dry, thereby forming an adhesive layer on the substrate. Next, a protective film forming layer composition is applied to the formed adhesive layer by a known method, and heated to dry, thereby manufacturing a protective film forming sheet having an adhesive layer and a protective film forming layer sequentially formed on the substrate.

Furthermore, an adhesive composition or the like is applied to the peeling treatment surface of the peeling sheet, and the adhesive composition is heated and dried to form an adhesive layer on the peeling sheet. Similarly, a protective film forming layer composition is applied to the peeling treatment surface of the peeling sheet, and the protective film forming layer is formed on the peeling sheet. Thereafter, the adhesive layer on the peeling sheet is bonded to a substrate, the peeling sheet is removed, and the adhesive layer is bonded to the protective film forming layer on the peeling sheet, thereby manufacturing a protective film forming sheet having an adhesive layer, a protective film forming layer, and a peeling sheet sequentially disposed on a substrate. The release sheet may be appropriately removed before using the protective film forming sheet.

When the protective film forming sheet has a buffer layer, the buffer layer composition can be applied in the same manner as above to form the buffer layer. When the protective film forming sheet has an adhesive layer, the adhesive layer composition can be applied in the same manner as above to form the adhesive layer.

(8. Method for manufacturing a substrate device) As an example of a method for manufacturing a substrate device using the protective film forming sheet of the present embodiment, a method for processing a workpiece having a convex electrode to obtain a workpiece is described.

The workpiece is a plate-shaped object to which the protective film forming sheet of the present embodiment is attached and processed. Examples of the workpiece include semiconductor wafers and semiconductor panels.

The convex electrode is an electrode formed by protruding from the surface of the workpiece, and is usually exemplified by a bump that performs the function of connecting the electrode, a pillar electrode, etc. The shape of the convex electrode is not particularly limited, and examples thereof include spherical, columnar, and conical shapes. In addition, the material of the convex electrode is not particularly limited as long as it is a conductive material, but is usually a solder-based material. In addition, the height of the convex electrode is not particularly limited, but is usually 5 to 1000 μm, preferably 50 to 500 μm.

The manufacturing method of the substrate device of this embodiment has at least the following steps 1 to 4. Step 1: A step of attaching the above-mentioned protective film forming sheet to the surface of the workpiece having a convex electrode, so that the protective film forming layer is in contact with the convex electrode Step 2: A step of peeling off the adhesive layer from the protective film forming layer before curing Step 3: A step of curing the protective film forming layer to form a protective film Step 4: A step of obtaining a workpiece processed by individualization from the workpiece having a convex electrode

In the present embodiment, as an example of a method for manufacturing a substrate device having the above-mentioned steps 1 to 4, the following method is described using Figures 1A to 6: a semiconductor wafer with bumps formed on a conductive surface of a semiconductor wafer as a workpiece and having bumps serving as convex electrodes is individualized to manufacture a semiconductor device having the bumps and circuits formed thereon.

As shown in FIG2 , a semiconductor wafer 100 with bumps is a wafer with bumps having bumps 102 provided on a conductive surface 101a of a semiconductor substrate 101. A plurality of bumps 102 are usually provided. The semiconductor wafer 100 is not particularly limited, but may be a silicon wafer, or a wafer made of ceramic, glass, sapphire, or the like.

(8.1 Step 1) In step 1, first, a protective film forming sheet 1 as shown in FIG. 1A or FIG. 1B is prepared. Then, as shown in FIG. 3 , the protective film forming sheet 1 is bonded to the surface (bump forming surface) 101a of the semiconductor wafer 100 with the protective film forming layer 30 as the bonding surface, so that the protective film forming layer 30 is in contact with the bump 102.

The protective film forming sheet 1 is bonded to the semiconductor wafer 100 preferably at 30 to 150°C, more preferably at 40 to 100°C.

The protective film forming sheet is preferably attached while being pressed, for example, preferably while being pressed by a pressing means such as a pressing roller. Alternatively, the protective film forming sheet can be pressed onto the semiconductor wafer 100 by a vacuum laminating machine.

In this embodiment, after the protective film forming sheet 1 is attached to the semiconductor wafer 100, as shown in Fig. 3, the bump 102 preferably protrudes on the adhesive layer side through the protective film forming layer 30. By protruding on the adhesive layer side in this way, it becomes easy to make the bump 102 contact the electrode on the chip mounting substrate and fix it by the reflow described later.

However, the bump 102 may be buried in the protective film forming layer 30 without passing through the protective film forming layer 30. Even in this state, in step 3 and the like, the bump 102 may be protruded by simply flowing the protective film forming layer 30 by heating.

(8.2 Step 2) In step 2, after step 1, the adhesive layer 20 and the substrate 10 (laminated sheet 50) attached to the surface of the semiconductor wafer 100 are peeled off from the protective film forming layer 30. After this peeling, as shown in FIG. 4, the protective film forming layer 30 remains on the semiconductor wafer 100.

In the case where the adhesive layer 20 is energy-ray-hardenable, the adhesive layer 20 is irradiated with energy rays to harden the adhesive layer 20 before the adhesive layer and the substrate are peeled off from the semiconductor wafer 100 in step 2. The adhesive layer 20 is hardened by energy-ray irradiation, whereby the tensile storage elastic modulus is within the above range. On the other hand, since the protective film forming layer has not yet been hardened, its shear storage elastic modulus is within the above range. Therefore, since both the adhesive layer 20 and the protective film forming layer 30 are in a state suitable for peeling, the adhesive layer 20 is in a state that can be easily peeled off at the interface with the protective film forming layer 30.

The time point for irradiating the adhesive layer 20 with energy rays to harden it is not particularly limited, and it can be hardened before attaching the protective film forming sheet to the semiconductor wafer 100. Alternatively, it can be hardened after attaching to the semiconductor wafer 100. In addition, the adhesive layer 20 can be irradiated with energy rays to a degree that it is not completely hardened before attaching the protective film forming sheet to the semiconductor wafer 100 to reduce the bonding strength, and at the same time, after attaching to the semiconductor wafer 100, it can be irradiated with energy rays to harden it again, so that the bonding strength is further reduced.

In addition, when the adhesive layer is not energy-ray-hardenable, the tensile storage modulus of the adhesive layer is within the above range. On the other hand, since the protective film-forming layer has not yet been hardened, its shear storage modulus is within the above range. Therefore, since both the adhesive layer and the protective film-forming layer are in a state suitable for peeling, the adhesive layer can be easily peeled off at the interface with the protective film-forming layer.

In the manufacturing method of this embodiment, the semiconductor wafer 100 is preferably back-ground. The back-ground grinding is performed with the protective film forming sheet attached to the conductive surface 101a side of the semiconductor wafer 100. That is, the back-ground grinding of the semiconductor wafer is performed between step 1 and step 2. Thus, the protective film forming sheet 1 is not only a sheet for supporting the protective film forming layer 30, but is also used as a wafer polishing sheet for protecting the bump forming surface during back-ground grinding.

The back side grinding of the semiconductor wafer is performed, for example, by fixing the surface (conductor surface) side of the semiconductor wafer to which the protective film forming sheet has been attached on a fixed worktable such as a suction cup, and grinding the back side by a grinder, etc. The thickness of the wafer after grinding is not particularly limited, but is generally 5 to 450 μm, preferably about 20 to 400 μm.

In the manufacturing method of the present embodiment, it is preferred that a protective sheet be attached to the back of the semiconductor wafer before the adhesive layer and the substrate are peeled off from the protective film forming layer. When the back of the semiconductor wafer is ground, as shown in FIG. 4 , the protective sheet 200 is attached to the back after grinding, and is used as a dicing sheet 200 in step 4 described later.

(8.3 Step 3) In step 2, after the adhesive layer is peeled off from the protective film forming layer, the protective film forming layer 30 remaining on the surface of the semiconductor wafer 100 is heated. Since the protective film forming layer 30 contains a thermosetting resin, it is thermally cured by the above heating and becomes a protective film 31 as shown in FIG. 4 .

The heating conditions are not particularly limited as long as the thermosetting resin contained in the protective film forming layer 30 can be cured. For example, the heating is performed at 80 to 200° C. for 30 to 300 minutes, preferably at 100 to 180° C. for 60 to 200 minutes.

(8.4 Step 4) Next, individualized semiconductor chips are obtained from the semiconductor wafer 100 having the protective film 31 formed on the bump formation surface. In the present embodiment, as shown in FIG5 , the semiconductor wafer 100 is divided by dicing to form a plurality of semiconductor chips 150 . In this step, the semiconductor wafer 100 and the protective film 31 are divided simultaneously according to the shape of the semiconductor chip 150 .

The cutting method is not particularly limited, but known methods such as blade cutting, invisible cutting, and laser cutting can be used.

For example, as shown in FIG. 5 , the semiconductor wafer 100 is supported by a dicing sheet 200 attached to the back side of the semiconductor wafer 100 , and a cut is made from the conductive surface 101 a side of the semiconductor wafer 100 .

The dicing sheet 200 is preferably larger than the semiconductor wafer 100, and its central area is attached to the semiconductor wafer 100, while the peripheral area is not attached to the semiconductor wafer 100 but attached to the support member 300. The support member 300 is a member for supporting the dicing sheet 200, and may be, for example, a ring frame.

In this embodiment, after dicing, the semiconductor chip 150 is picked up by a known method. As shown in FIG6 , the picked up semiconductor chip 150 is mounted on the chip mounting substrate 160 and then fixed to the chip mounting substrate 160 via the bumps 102 by reflow. If necessary, the gap between the semiconductor chip 150 and the chip mounting substrate 160 is sealed by a sealing resin to manufacture a semiconductor device 170.

Although the above is an explanation of the implementation form of the present invention, the present invention is not limited to the above implementation form and can be modified in various forms within the scope of the present invention. [Implementation Examples]

The present invention is described in more detail below using embodiments, but the present invention is not limited to these embodiments.

The measurement method and evaluation method in this embodiment are as follows.

(Measurement of the tensile storage modulus of the adhesive layer) A PET-based release film (manufactured by LINTEC: SP-PET381031, thickness: 38μm) was attached to both sides of the adhesive layer (thickness 200μm) to prepare a laminate. In the case where the adhesive contained in the adhesive layer is energy-ray-curable, it was cured by irradiating with ultraviolet rays using an ultraviolet irradiation device (RAD-2000m/12) manufactured by LINTEC under irradiation conditions of 230mW/ ^cm2 of illumination and 500mJ/ ^cm2 of accumulated light. Then, the obtained laminate was cut into a size of 4mm×50mm to obtain a sample for measuring the tensile storage modulus. The obtained sample was subjected to a strain at a frequency of 1 Hz using a viscoelasticity measuring device (manufactured by ORIENTEC: RHEOVIBRON), and the tensile storage modulus at -30 to 200°C was measured. The tensile storage modulus at 23°C was calculated from the equivalent value.

(Measurement of shear storage modulus of protective film forming layer) PET-based release films (LINTEC: SP-PET381031, thickness: 38μm) were attached to both sides of the protective film forming layer (thickness 1000μm) to prepare a laminate. Then, the obtained laminate was cut into a disc shape with a diameter of 8mm to obtain a sample for measuring the shear storage modulus.

The sample setting position of the shear viscosity measuring device is maintained at 90°C in advance, and the sample obtained above is placed on this setting position. The measuring fixture is pushed on the sample to fix the sample in the setting position. Then, the shear storage elastic modulus of the sample is measured at a temperature of 23°C and a measuring frequency of 1Hz.

(Measurement of Adhesive Strength of Adhesive Layer) The protective film forming sheet produced by the embodiment and the comparative example was cut into 25 mm width and attached to the adherend, i.e., the silicon mirror wafer, using a roller weighing 2 kg. At this time, the silicon mirror wafer was heated to 70°C on a hot plate. After attachment, it was stored in an environment of 23°C and 50% RH for 1 hour. After irradiating with ultraviolet rays at an irradiation rate of 15 mm/sec using a UV irradiation device (RAD-2000m/12) manufactured by LINTEC, the samples were placed in a specified temperature environment for 5 minutes, and then the adhesive layer was peeled off from the protective film forming layer using a tensile tester (TENSILON manufactured by ORIENTEC) at a peeling angle of 180° and a peeling rate of 100 mm/min. to measure the adhesive force.

(Evaluation of the peeling property of the adhesive layer) The protective film forming sheet produced by the embodiment and the comparative example was attached to a wafer (8-inch wafer made by Waltz) with bumps of 200μm height, 400μm pitch, and 250μm diameter using a bonding machine (RAD-3510F/12) manufactured by LINTEC. In addition, during the bonding, the bonding table of the device was set to 90°C. After bonding, ultraviolet rays were irradiated at an irradiation speed of 15mm/sec using an ultraviolet irradiation device (RAD-2000m/12) manufactured by LINTEC.

LINTEC dicing tape (D-676H) and annular frame were attached to the back of the wafer at the same time, and the peeling evaluation was performed using LINTEC's BG tape peeling device (RAD-2700). In addition, the peeling speed was set to 2mm/sec, the table temperature was set to room temperature, and the heat seal was S-32B. If the adhesive layer can be peeled off from the protective film formation layer without stopping the device, it is evaluated as "○ (good)", and if it causes the device to stop, the heat seal to separate, or the wafer to be damaged, it is evaluated as "╳ (bad)".

(Evaluation of cracks in the protective film forming layer) The protective film forming sheet produced by the embodiment and the comparative example was cut into a size of 30 cm × 100 cm, and the entire amount was wrapped around a plastic core with an inner diameter of 3 inches and a length of 35 cm, with the substrate side becoming the outer side. After standing for 5 minutes, the protective film forming layer removed from the core was visually checked for cracks. If the protective film forming layer was not cracked, it was evaluated as "○ (good)", and if the protective film forming layer was cracked, it was evaluated as "╳ (bad)".

(Substrate and Buffer Layer) A PET film ("Lumirror (registered trademark)" manufactured by TORAY, thickness 100 μm) was prepared as a substrate. Using a small T-die (T-DIE) extruder ("LABO PLASTOMILL" manufactured by Toyo Seiki Seisaku-sho Co., Ltd.), an ethylene-vinyl acetate copolymer resin ("EVAFLEX (registered trademark) EV260" manufactured by DOW-MITSUI POLYCHEMICALS Co., Ltd.) and an ethylene-α-olefin copolymer ("TAFMER DF640" manufactured by Mitsui Chemicals Co., Ltd.) were co-extruded into a PET film, thereby laminating an adhesion layer composed of an ethylene-vinyl acetate copolymer resin and a buffer layer composed of an ethylene-α-olefin copolymer (thickness 400μm) in this order on the substrate. The physical properties of ethylene-vinyl acetate copolymer resin are density 950kg/m ³ , melting point less than 72°C, and melt flow rate (190°C) 6g/10min. The physical properties of ethylene-α-olefin copolymer are density 864kg/m ³ , melting point less than 50°C, melt flow rate (190°C) 3.6g/10min, and melt flow rate (230°C) 6.7g/10min.

(Protective film forming layer) The following components were mixed at various blending ratios (solid content conversion), and diluted with methyl ethyl ketone so that the solid content concentration became 55 mass %, to prepare a coating agent for a protective film forming layer. The prepared coating agent was applied to a PET-based release film (manufactured by LINTEC: SP-PET381031, thickness: 38μm), and dried to obtain a sheet having a protective film forming layer A with a thickness of 30μm. (a) Adhesive polymer: PVB resin (manufactured by Sekisui Chemical Industry, SV-10) blending ratio: 9.9% (b-1) Bisphenol A type epoxy resin (manufactured by DIC, EXA-4810-1000) blending ratio: 37.8% (b-2) Dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink and Chemicals, EPICLON HP-7200, epoxy equivalent 254-264 g/eq) blending ratio: 25% (c) Novolac type phenolic resin (manufactured by Showa Denko Co., Ltd., Shonol BRG-556) blending ratio: 18.1% (d) Curing accelerator: 2-phenyl-4,5-dihydroxymethimidazole (SHIKOKU CHEMICALS, CUREZOL 2PHZ) blending ratio is 0.2% (e) Silica filler (Admatechs, YA050C-MKK, average particle size 0.05μm) blending ratio is 9%

The following components were mixed at various blending ratios (solid content conversion), and diluted with methyl ethyl ketone so that the solid content concentration became 55 mass %, to prepare a coating agent for a protective film-forming film. The prepared coating agent was applied to a PET-based release film (manufactured by LINTEC: SP-PET381031, thickness: 38μm), and dried to obtain a sheet having a protective film-forming layer B with a thickness of 30μm. (a) Adhesive polymer: PVB resin (SV-10, manufactured by Sekisui Chemical Industries) with a blending ratio of 10.16% (b-1) Bisphenol A epoxy resin (EP-4088L, manufactured by DIC) with a blending ratio of 34.79% (b-2) Dicyclopentadiene epoxy resin (EPICLON HP-7200HH, manufactured by Dainippon Ink and Chemicals) with a blending ratio of 26.63% (c) Novolac phenol resin (Showa Denko Co., Ltd., Shonol BRG-556) with a blending ratio of 19.09% (d) Curing accelerator: 2-phenyl-4,5-dihydroxymethimidazole (CUREZOL, manufactured by SHIKOKU CHEMICALS Corporation) 2PHZ) blending ratio is 0.2% (e) silica filler (Admatechs, YA050C-MKK, average particle size 0.05μm) blending ratio is 9.13%

The following components were mixed at various blending ratios (converted to solid content), and diluted with methyl ethyl ketone to a solid content concentration of 55 mass % to prepare a coating agent for a protective film forming layer. The prepared coating agent was applied to a PET-based release film (manufactured by LINTEC: SP-PET381031, thickness: 38μm), and dried to obtain a sheet having a protective film forming layer C with a thickness of 30μm. (a) Adhesive polymer: PVB resin (KS-10, manufactured by Sekisui Chemical Industry Co., Ltd.) with a blending ratio of 10.4% (b-1) Bisphenol A type epoxy resin (EXA-4810-1000, manufactured by DIC) with a blending ratio of 34.3% (b-2) Dicyclopentadiene type epoxy resin (EPICLON HP-7200, manufactured by Dainippon Ink and Chemicals Co., Ltd., epoxy equivalent 254 to 264 g/eq) with a blending ratio of 23.7% (c) Novolac type phenolic resin (Showa Denko Co., Ltd., Shonol BRG-556) with a blending ratio of 22% (d) Curing accelerator: 2-phenyl-4,5-dihydroxymethimidazole (SHIKOKU CHEMICALS Corporation, CUREZOL 2PHZ) blending ratio is 0.2% (e) Silica filler (Admatechs, YA050C-MKK, average particle size 0.05μm) blending ratio is 9.4%

(Example 1) (Preparation of adhesive layer) To an acrylic adhesive (Mw: 900000) composed of 80 parts by mass of 2-ethylhexyl acrylate (2EHA) and 20 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio became 40% relative to the mass of HEA to prepare an adhesive. That is, the amount of 2-isocyanatoethyl methacrylate added was 8 parts.

To 100 parts by mass of the adhesive, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by BASF) was added as a photoinitiator, and 0.5 parts by mass of a polyvalent isocyanate compound (CORONATE L manufactured by Tosoh Corporation) was added as a crosslinking agent, and the mixture was stirred for 30 minutes to prepare an adhesive composition.

(Production of protective film forming sheet) Then, the prepared adhesive composition solution was applied to a PET-based release film (SP-PET381031 manufactured by LINTEC, thickness 38μm), dried to form an adhesive layer with a thickness of 10μm, and an adhesive sheet was produced. The produced adhesive sheet was bonded to the buffer layer side of the buffer layer with a substrate produced above, and a sheet having a protective film forming layer A formed thereon was bonded to the adhesive sheet to obtain a protective film forming sheet.

(Example 2) To an acrylic adhesive (Mw: 900000) composed of 96 parts by mass of 2-ethylhexyl acrylate (2EHA) and 4 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio became 50% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 2 parts. Otherwise, a protective film forming sheet was prepared in the same manner as in Example 1.

(Example 3) To an acrylic adhesive (Mw: 900000) composed of 90 parts by mass of 2-ethylhexyl acrylate (2EHA) and 10 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio was 40% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 4 parts. The other steps were similar to those of Example 1 to prepare a sheet for forming a protective film.

(Example 4) To an acrylic adhesive (Mw: 900000) composed of 82 parts by mass of 2-ethylhexyl acrylate (2EHA) and 18 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio was 33% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 6 parts. The other steps were similar to those of Example 1 to prepare a sheet for forming a protective film.

(Example 5) To an acrylic adhesive (Mw: 900000) composed of 90 parts by mass of 2-ethylhexyl acrylate (2EHA) and 10 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio became 80% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 8 parts. Otherwise, a protective film forming sheet was prepared in the same manner as in Example 1.

(Example 6) To an acrylic adhesive (Mw: 900000) composed of 80 parts by mass of 2-ethylhexyl acrylate (2EHA) and 20 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio became 40% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 8 parts.

To 100 parts by mass of the adhesive, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 manufactured by BASF) was added as a photoinitiator, and 0.5 parts by mass of a polyvalent isocyanate compound (CORONATE L manufactured by Tosoh Corporation) was added as a crosslinking agent, and the mixture was stirred for 30 minutes to prepare an adhesive composition.

Next, the prepared adhesive composition solution was applied to a PET-based release film (SP-PET381031 manufactured by LINTEC, thickness 38 μm), and dried to form an adhesive layer with a thickness of 10 μm to prepare an adhesive sheet. The prepared adhesive sheet was attached to the buffer layer side of the buffer layer attached to the substrate, and then a sheet having a protective film forming layer B formed thereon was attached to the adhesive sheet to obtain a protective film forming sheet.

(Example 7) An acrylic adhesive (Mw: 900000) composed of 96 parts by mass of 2-ethylhexyl acrylate (2EHA) and 4 parts by mass of 2-hydroxyethyl acrylate (HEA) was prepared.

To 100 parts by mass of the adhesive, 4.3 parts by mass of a polyvalent isocyanate compound (CORONATE L manufactured by Tosoh Corporation) was added as a crosslinking agent, and the mixture was stirred for 30 minutes to prepare an adhesive composition.

(Comparative Example 1) To an acrylic adhesive (Mw: 900000) composed of 80 parts by mass of 2-ethylhexyl acrylate (2EHA) and 20 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio was 80% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 16 parts. Otherwise, a protective film forming sheet was prepared in the same manner as in Example 1.

(Comparative Example 2) To an acrylic adhesive (Mw: 900000) composed of 80 parts by mass of 2-ethylhexyl acrylate (2EHA) and 20 parts by mass of 2-hydroxyethyl acrylate (HEA), 2-isocyanatoethyl methacrylate (Karenz MOI manufactured by Showa Denko) was added in such a manner that the addition ratio was 60% relative to the mass of HEA to prepare an adhesive composition. That is, the amount of 2-isocyanatoethyl methacrylate added was 12 parts. Otherwise, a protective film forming sheet was prepared in the same manner as in Example 1.

(Comparative Example 3) An adhesive composition was prepared in the same manner as in Example 4. A solution of the prepared adhesive composition was applied to a PET-based release film (SP-PET381031 manufactured by LINTEC, thickness 38 μm), and dried to form an adhesive layer with a thickness of 10 μm to prepare an adhesive sheet. The prepared adhesive sheet was bonded to the buffer layer side of the buffer layer attached to the substrate, and a sheet having a protective film forming layer C formed thereon was bonded to the adhesive sheet to obtain a sheet for forming a protective film.

The above-mentioned measurements and evaluations were performed on the obtained samples (Examples 1 to 7, Comparative Examples 1 to 3). The results are shown in Table 1.

[Table 1] Protective film forming layer Adhesive layer Shear storage elastic modulus at 23°C Rupture Evaluation Tensile storage modulus at 23°C MOI Addition Components Adhesion Separability (MPa) (MPa) (share) (mN/25mm) Embodiment 1 1930 ○ 15 8 1450 ○ Embodiment 2 1930 ○ 0.5 2 1100 ○ Embodiment 3 1930 ○ 2.8 4 780 ○ Embodiment 4 1930 ○ 7.6 6 900 ○ Embodiment 5 1930 ○ 19 8 570 ○ Embodiment 6 2650 ○ 15 8 800 ○ Comparison Example 1 1930 ○ 106 16 2230 ╳ Comparison Example 2 1930 ○ 55 12 1940 ╳ Embodiment 7 1930 ○ 0.5 0 1150 ○ Comparison Example 3 3200 ╳ 7.6 6 540 ○

From Table 1, it can be confirmed that when the shear storage modulus of the protective film forming layer at 23°C and the tensile storage modulus of the adhesive layer at 23°C are within the above ranges, the adhesive force of the adhesive layer is appropriately controlled and the peeling property of the adhesive layer is good. In addition, it can be confirmed that when the shear storage modulus of the protective film forming layer at 23°C is higher than the above range, when the protective film forming sheet is bent, cracks are generated in the protective film forming layer.

1: Sheet for forming protective film 10: Base material 20: Adhesive layer 30: Protective film forming layer 31: Protective film 40: Buffer layer

[FIG. 1A] is a schematic cross-sectional view of an example of a protective film forming sheet of the present embodiment; [FIG. 1B] is a schematic cross-sectional view of another example of a protective film forming sheet of the present embodiment; [FIG. 2] is a schematic cross-sectional view of an example of a semiconductor wafer on which bumps have been formed; [FIG. 3] is used to illustrate the step of attaching the protective film forming sheet of the present embodiment to the bump forming surface of the semiconductor wafer on which bumps have been formed. [Fig. 4] is a cross-sectional schematic diagram for explaining the step of hardening the protective film forming layer peeled off from the protective film forming sheet to form a protective film; [Fig. 5] is a cross-sectional schematic diagram for explaining the step of singulating a semiconductor chip from a semiconductor wafer on which a protective film has been formed; and [Fig. 6] is a cross-sectional schematic diagram for explaining the step of obtaining a semiconductor device from the singulated semiconductor chip.

1: Sheet for forming protective film

10: Base material

20: Adhesive layer

30: Protective film formation layer

50: Laminated sheet

Claims (6)

A protective film forming sheet, which has a substrate, an energy ray-curable adhesive layer on the substrate, and a curable protective film forming layer in order, wherein the protective film forming layer is formed on the convex electrode forming surface of a workpiece having a convex electrode by being attached to the convex electrode forming surface and cured, and the protective film forming layer before curing has a shear storage elastic modulus of 3000 MPa or less at 23°C, and the adhesive layer after energy ray irradiation has a tensile storage elastic modulus of 45 MPa or less at 23°C. A protective film forming sheet, which has a substrate, an adhesive layer on the substrate, and a curable protective film forming layer in order, wherein the protective film forming layer is formed on the convex electrode forming surface of a workpiece having a convex electrode by being attached to the convex electrode forming surface and cured, and the protective film forming layer before curing has a shear storage elastic modulus of 3000 MPa or less at 23°C, and a tensile storage elastic modulus of 45 MPa or less at 23°C of the adhesive layer. The protective film forming sheet as described in claim 1 or 2, wherein the adhesive layer has a reaction product, the reaction product is an energy-ray-curable compound having an isocyanate group added to an acrylic monomer containing a hydroxyl group, and the content ratio of the energy-ray-curable compound having an isocyanate group is 10% by mass or less relative to 100% by mass of the acrylic monomer containing a hydroxyl group. The protective film forming sheet as described in claim 1 or 2, wherein a buffer layer is provided between the substrate and the adhesive layer. A method for manufacturing a substrate device comprises the following steps: attaching a protective film forming sheet having a substrate, an energy ray-curable adhesive layer on the substrate, and a curable protective film forming layer to a convex electrode forming surface of a workpiece having a convex electrode, so that the protective film forming layer is in contact with the convex electrode; peeling off the protective film forming layer before curing after energy ray irradiation The step of forming an adhesive layer; the step of hardening the aforementioned protective film forming layer to form a protective film; and the step of obtaining a workpiece processed by individualization from a workpiece having a convex electrode, wherein the protective film forming layer before hardening has a shear storage elastic modulus of less than 3000MPa at 23°C, and the adhesive layer after energy ray irradiation has a tensile storage elastic modulus of less than 45MPa at 23°C. A method for manufacturing a substrate device comprises the following steps: attaching a protective film forming sheet having a substrate, an adhesive layer on the substrate and a curable protective film forming layer in sequence to a convex electrode forming surface of a workpiece having a convex electrode so that the protective film forming layer is in contact with the convex electrode; peeling off the adhesive layer from the protective film forming layer before curing; The step of forming a protective film layer; the step of hardening the protective film forming layer to form a protective film; and the step of obtaining a workpiece processed by individual pieces from a workpiece having a convex electrode, wherein the protective film forming layer before hardening has a shear storage elastic modulus of less than 3000MPa at 23°C, and the adhesive layer has a tensile storage elastic modulus of less than 45MPa at 23°C.

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