JPH10100355A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a release film having a release layer reduced in the content of impurities and suppressing the transfer of impurities in the film to be surface of the release layer by applying specific cured matter to the single surface of a polyethylene-2,6-naphthalate film and providing a silicone release layer having a specific residual adhesion ratio thereon. SOLUTION: An ethanol soln. of Si(OC2 H5 )4 is applied to at least the single surface of a polyethylene-2,6-naphthalate film and the coating layer is heated to 120-210 deg.C for 10-60sec not only to be dried by removing a solvent but also to be crosslinked and cured to form a primer layer of which the wall thickness is set to 0.02-2μm. Further, a silicone release layer of which the residual adhesion ratio is 95% or more is provided on the primer layer. As a curable silicone resin to be used, any reaction type one, for example, a condensation reaction type one, an addition reaction type one, an ultraviolet or electron beam curing type one can be used alone or in combination of two or more ones.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
More particularly, the present invention relates to a release film having excellent release properties, containing a small amount of impurities in a release layer, and suppressing migration of impurities in the film to the surface of the release layer. The present invention relates to a release film useful as a protective film for an adhesive used in a back grinding and dicing step in the production of a wafer.

[0002]

2. Description of the Related Art In a back grinding and dicing step in the production of a silicon wafer, an adhesive film having various adhesive layers laminated thereon is used for fixing a wafer.

In particular, in the back grinding step, the surface on which the circuit is printed is fixed with an adhesive layer, and the adhesive layer is peeled off after polishing the back surface. Therefore, if there is a slight peeling of the adhesive or transfer of impurities from the adhesive protective film, a problem such as a defective printed circuit occurs and the yield of the semiconductor chip is reduced.

In the dicing step, the silicone wafer is finely cut while being fixed to the pressure-sensitive adhesive layer. After the adhesive force of the pressure-sensitive adhesive is gradually reduced by UV irradiation or the like, the silicon wafers are taken out one by one. The removed wafer is
It is transferred to the next bonding step and molding step and used. And the above adhesive film is usually
The pressure-sensitive adhesive layer is stored with its surface protected by a release film, and the release film is peeled off and used in the above-mentioned dicing step.

In recent years, the size of a silicone wafer used in a molding process has become extremely small. However, if even a small amount of impurities is present on the surface of the wafer, cracks and the like due to poor adhesion originating from that portion occur, and the product yield is reduced. There is a problem of lowering.

On the other hand, the pressure-sensitive adhesive layer protective film includes
For example, a release film in which a silicone release layer is provided on a polyester film is conventionally used. However, such a release film has a disadvantage that impurities (oligomers and metal compounds used as polymerization catalysts) in the polyester film migrate in the silicone release layer and are easily deposited on the surface of the release layer. Then, the impurities deposited on the release layer surface are transferred to the adhesive layer surface of the adhesive film,
Further, when the above-mentioned silicone wafer is manufactured, it is re-transferred to the silicone wafer in the back grinding and dicing steps, which causes a reduction in product yield in the molding step. Further, the presence of impurities (uncured silicone monomers or oligomers) in the silicone resin constituting the release layer of the release film also causes a reduction in yield.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art, to reduce the amount of impurities in the release layer and to prevent the impurities in the film from migrating to the surface of the release layer. An object of the present invention is to provide a release film useful as a protective film for an adhesive used in a back grinding and dicing process in the production of a silicone wafer.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a polyethylene-2,6-naphthalate film on at least one side thereof.
A release film formed by applying a cured product of i (OC ₂ H ₅ ) ₄ to a thickness of 0.02 to 2 μm and further providing a silicone release layer having a residual adhesion rate of 95% or more.

As the polyethylene-2,6-naphthalate film of the present invention, a homopolymer having ethylene-2,6-naphthalate as a total repeating unit or at least 80 mol% of the total repeating unit is ethylene-2,6.
-A copolymer which is naphthalate is preferably used.

The copolymer component constituting the copolymer is mainly a compound having two ester-forming functional groups in the molecule. Specific examples thereof include oxalic acid, adipic acid, phthalic acid, isophthalic acid, terephthalic acid, and the like. 2,7
Dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyl ether dicarboxylic acid and the like; p-oxybenzoic acid, p
An oxycarboxylic acid such as oxyethoxybenzoic acid;
Propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexanedimethanol, neopentyl glycol,
Examples thereof include dihydric alcohols such as diethylene glycol.

Further, polyethylene-2,6-naphthalate may be obtained by blocking some or all of the terminal hydroxyl groups and / or carboxyl groups with a monofunctional compound such as benzoic acid or methoxypolyalkylene glycol. Alternatively, it may be modified with a very small amount of a trifunctional or higher-functional polyfunctional compound such as glycerin, pentaerythritol or the like within a range where a substantially linear polymer can be obtained.

As the polyethylene-2,6-naphthalate, a homopolymer containing ethylene-2,6-naphthalate as substantially all repeating units is preferable. Such polyethylene-2,6-naphthalate can contain additives such as stabilizers, UV absorbers, colorants, flame retardants and the like.

The polyethylene-2,6-naphthalate according to the present invention may contain a small proportion of inert fine particles in order to impart lubricity to the film.

Examples of such inert fine particles include inorganic particles such as silica spherical particles, calcium carbonate, alumina and zeolite, and heat-resistant organic particles such as crosslinked silicone particles and crosslinked polystyrene particles.
The inorganic particles are preferably synthetic products as compared with natural products, and can take any crystal form.

The above-mentioned inert fine particles have an average particle size of 0.05.
It is preferably in the range of .about.1.5 .mu.m. In particular, when the inert particles are inorganic particles, the average particle size is 0.1 to 0.8.
μm, more preferably 0.2 to 0.5 μm
m is particularly preferred. When the inert fine particles are crosslinked silicone resin particles, the average particle size is 0.1 to 1.5 μm.
Particularly preferably, it is in the range of m. When the inert fine particles are cross-linked polystyrene particles, the average particle size is 0.1%.
More preferably, it is in the range of １1 μm.

When the average particle size of the inert fine particles is smaller than 0.05 μm, the effect of improving the film's slipperiness, abrasion resistance or winding property is small, while the average particle size is 1.5 μm.
If it is larger than m, the film surface becomes too rough, which is not preferable.

The content of the inert fine particles is preferably 0.001% by weight or more, more preferably 0.005 to 20% by weight. If the content is less than 0.001% by weight, the film slip property becomes insufficient, which is not preferable.

The timing of adding the inert fine particles is not particularly limited as long as it is a stage before the formation of polyethylene-2,6-naphthalate, and may be, for example, a polymerization stage or a stage before the film formation.

The polyethylene-2,6 used in the present invention
-The naphthalate film can be produced by a conventionally known method. For example, polyethylene-2,
After 6-naphthalate is dried, it is melted in an extruder at a temperature of Tm to (Tm + 70) ° C. (where Tm is the melting point of polyethylene-2,6-naphthalate) and a die (eg, T-die, I-die, etc.) Extruded onto a rotating cooling drum from
An unstretched film is produced by quenching at ~ 90 ° C, and then the unstretched film is stretched at a temperature of (Tg-10) to (Tg + 70) ° C (Tg: glass transition temperature of polyethylene-2,6-naphthalate) in the machine direction. Stretched at a ratio of 2.5 to 8.0 times, stretched at a ratio of 2.5 to 8.0 times in the transverse direction, and heat-set at a temperature of 180 to 250 ° C for 1 to 60 seconds as necessary. Can be manufactured. The thickness of the film is 1-10
0 μm is preferable, and 25 to 75 μm is more preferable.

In the present invention, polyethylene-2,6
-On at least one side of the naphthalate film, to prevent impurities in the film from migrating to the release layer surface,
Si (OC ₂ H ₅₎ 0.02~ the ₄ compounds were cured by crosslinking
A primer layer having a thickness of 2 μm is provided.

The primer layer in the present invention is formed, for example, by adding an ethanol solution of the aforementioned compound to polyethylene-2,6.
-It can be applied by coating on at least one side of a naphthalate film, heating at a temperature of, for example, 120 to 210C for 10 to 60 seconds to dry and remove the solvent, and crosslinking and curing.

When an ethanol solution of a Si (OC ₂ H ₅ ) ₄ compound is applied to a film, as the ethanol of the solvent evaporates, the water in the air comes into contact with the Si (OC ₂ H ₅ ) ₄ compound to obtain the following formula: The reaction proceeds according to
Is generated.

[0023]

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The compound A undergoes a dehydration-condensation reaction of silanol groups during drying by heating to form a uniform layer.

In the present invention, the thickness of the primer layer is
0.02 to 2 μm. When the thickness is less than 0.02 μm, the effect of suppressing the migration of impurities in the film to the surface of the release layer is insufficient, and when the thickness exceeds 2 μm, the blocking resistance of the film on which the primer layer is laminated is poor. Is not preferred.

In the present invention, a silicone release layer having a residual adhesion of 95% or more is provided on the primer layer.

The silicone resin coating film can be formed by applying a coating liquid containing a curable silicone resin on at least one side of the film, drying and curing.

As the curable silicone resin, any reaction system such as a condensation reaction system, an addition reaction system, and an ultraviolet or electron beam curing system can be used. One or more of these can be used.

The curing reaction of various silicones can be shown as follows.

[0030]

Embedded image

As the silicone resin of the condensation reaction system, for example, a polymethylsiloxane having a terminal —OH group and a polydimethylsiloxane (hydrogensilane) having a terminal —H group are used as an organic tin catalyst (for example, an organic tin acylate catalyst). ) To form a three-dimensional crosslinked structure.

As the silicone resin of the addition reaction system, for example, polydimethylsiloxane having a vinyl group introduced into a terminal and hydrogensilane are reacted using a platinum catalyst,
One that creates a three-dimensional structure is exemplified.

As the ultraviolet curing silicone resin,
For example, the most basic type uses the same radical reaction as ordinary silicone rubber crosslinking, the one that introduces an acrylic group and photocures, the one that decomposes onium salts with ultraviolet rays to generate a strong acid, and this converts the epoxy group into an epoxy group. Examples thereof include those that are cleaved and crosslinked, and those that are crosslinked by the addition reaction of thiol to vinylsiloxane. Electron beams have higher energy than ultraviolet rays, and a radical crosslinking reaction occurs without using an initiator as in the case of ultraviolet curing.

The curable silicone resin preferably has a degree of polymerization of about 500,000 to 200,000, preferably about 1,000 to 100,000. Specific examples thereof include KS-718 manufactured by Shin-Etsu Chemical Co., Ltd. -774, -775, -77
8, -779H, -830, -835, -837, -8
38, -839, -841, -843, -847, -8
47H, X-62-2418, -2422, -212
5, -2492, -2494, -470, -2366,
-630, X-92-140, -128, KS-723
A / B, -705F, -708A, -883, -70
9, -719; TPR-670 of Toshiba Silicone Co., Ltd.
1, -6702, -6703, -3704, -670
5, -6722, -6721, -6700, XSR-7
029, YSR-3022, YR-3286; DK-Q3-202, -203, -2 manufactured by Dow Corning Co., Ltd.
04, -210, -240, -3003, -205,-
3057, SFXF-2560; Toray Silicone Co., Ltd.
SD-7226, -7320, -7229, BY2
4-900, -171, -312, -374, SRX-
375, SYL-OFF23, SRX-244, SEX
-290; SI manufactured by ICI Japan Ltd.
LCOLASE 425 and the like. Also, JP-A-47-34447, JP-B-52-40
No. 918 can also be used.

When the cured silicone resin film is formed on the film surface, a conventionally known method such as a bar coating method, a doctor blade method, a reverse roll coating method or a gravure roll coating method is used as a coating method. it can.

It is necessary to carry out drying and curing (thermal curing, ultraviolet curing, etc.) of the coating film so that the residual adhesion ratio is 95% or more. Drying and curing can be performed individually or simultaneously. When performing simultaneously, it is preferable to perform at 100 degreeC or more. The conditions for drying and curing are 1
The temperature is preferably not less than 00 ° C. and not less than 30 seconds. Drying temperature is 100
If the temperature is lower than 0 ° C. and the curing time is less than 30 seconds, the curing of the coating film is incomplete, and the coating film tends to fall off, which is not preferable.

The thickness of the curable silicone resin coating is not particularly limited, but is preferably in the range of 0.05 to 0.5 μm. If the thickness is less than 0.05 μm, the demolding performance deteriorates and satisfactory performance cannot be obtained. On the other hand, if the thickness exceeds 0.5 μm, it takes a long time for curing, which is not preferable because it causes production inconvenience.

The release layer in the present invention may contain various known additives as long as the object of the present invention is not hindered. Such additives include, for example, ultraviolet absorbers, pigments, defoamers and the like.

[0039]

The present invention will be described below in detail with reference to examples. The physical property values and characteristic values in the present invention were measured by the following methods.

(1) Analysis of Metal Element on Release Layer Surface A polyester adhesive tape (Nitto 31B manufactured by Nitto Boseki Co., Ltd.) was attached to the release layer surface of the release film, and the pressure was 5 kg / cm ² with a pressure roller. Pressure bonding, 2 at 70 ° C
After leaving for 0 hour, the adhesive tape was peeled off from the release film, and the metal element on the release surface of the adhesive tape was analyzed by an ESCA apparatus using Mg 励 起 α (1254 eV) as an excitation source. The transferred metal element was determined. In addition, in the measurement of the metal element by ESCA, a metal element having a peak of 500 count or more was determined as a metal element detected.

(2) Measurement of oligomer The release film was heated in an oven at 180 ° C. for 5 minutes, taken out and cooled, and the release layer surface of the release film was subjected to A
u, and the surface of the 10 μm square area was 2000 × with a scanning electron microscope.
Observation was conducted at 0 places, and when no oligomer crystals (hexagonal columnar crystals) were observed at any of the observed places, it was determined that no oligomer was present on the release layer surface of the release film.

(3) Residual Adhesion Rate JIS polyester adhesive tape (Nitto 31B)
Cold rolled stainless steel sheet (SUS3
04) was measured for the peeling force after application, and the result was taken as the basic adhesive force (f ₀ ). Also, the polyester adhesive tape was adhered to the release layer coating surface of the sample film, and 5 kg
And then left for 30 seconds to peel off the adhesive tape. Then, the peeled adhesive tape was stuck on the above stainless steel plate, and the peeling force of the stuck portion was measured to obtain a residual adhesive force (f). From the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), a residual adhesive rate was determined using the following equation.

[0043]

## EQU1 ## Residual adhesion rate (%) = (f / f ₀ ) × 100

(4) Peeling strength A polyester adhesive tape (Nitto 31B) was adhered to the release layer surface of the release film, pressed with a 5 kg pressure roller, left for 20 hours, and then peeled off between the release layer and the adhesive tape ( R _f0 ) was measured with a tensile tester.

Example 1 An antimony compound and a manganese compound were used as catalysts to polymerize to an intrinsic viscosity of 0.1.
The polyethylene-2,6-naphthalate of Example 62 was melted by an extruder, and the molten polymer in the form of a film was extruded from a die onto a rotating drum maintained at about 40 ° C. Was rapidly cooled while closely adhering to the cooling drum to obtain an unstretched film. Next, the unstretched film was stretched 3.7 times in the machine direction, then 3.8 times in the transverse direction, and heat-set at 240 ° C. to obtain a biaxially oriented film having a thickness of 50 μm.
An isopropyl alcohol solution of Si (OC ₂ H ₅ ) ₄ (Colcoat P, manufactured by Colcoat Co., Ltd.) is coated on the film by a gravure coating method, and dried and cured at 140 ° C. for 30 seconds to form a 0.5 μm film. A thick anchor coat was obtained.

Next, a silicone resin coating solution having the following composition was applied to the surface of the biaxially stretched film on which the anchor coat layer was coated at a coating amount of 8 g / m ² (wet), and dried at 130 ° C. for 30 seconds. After curing, a release film having a release layer thickness of 0.24 μm was obtained. Table 1 shows the performance of the release film.

<Composition of Silicone Resin Coating Solution> Cured silicone resin (KS847H; manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by weight Catalyst (CAT PL-50T; manufactured by Shin-Etsu Chemical Co., Ltd.) 2 parts by weight Diluent solvent: methyl ethyl ketone / Xylene / methyl isobutyl ketone mixed solvent 898 parts by weight

[Comparative Example 1]
Polyethylene terephthalate obtained by polymerizing dimethyl terephthalate and ethylene glycol in place of 2,6-naphthalate using an antimony compound and a manganese compound as a catalyst (intrinsic viscosity measured in o-chlorophenol at 25 ° C: 0.65 A release film was obtained in the same manner as in Example 1 except that (1) was used. Table 1 shows the performance of the release film.

[Comparative Example 2] Instead of coating an anchor coat layer on the surface of a polyethylene-2,6-naphthalate film, the polyethylene-2,6-naphthalate film was subjected to corona treatment so that the surface had a wetting index of 50 dyn / cm. A release film was obtained in the same manner as in Example 1 except that a silicone resin coating solution was applied to the surface. Table 1 shows the performance of the release film.

[Comparative Example 3]
A release film was obtained in the same manner as in Example 1 except that the amount was changed to 5 parts by weight. Table 1 shows the performance of the release film.

[0051]

[Table 1]

[0052]

According to the present invention, it is possible to provide a release film in which the amount of impurities in the release layer is small and the migration of impurities in the film to the surface of the release layer is suppressed. This release film is extremely useful as a protective film for an adhesive used in a back grinding and dicing step in the production of a silicone wafer.

Claims (2)

[Claims] 1. A cured product of Si (OC ₂ H ₅ ) ₄ having a thickness of 0.02 to 2 μm is coated on at least one surface of a polyethylene-2,6-naphthalate film, and a residual adhesion rate is further applied thereon. A release film provided with a silicone release layer of 95% or more. 2. The release film according to claim 1, which is used as a protective film of an adhesive for silicone wafer production.