DE112022005024T5 - Self-adhesive tape - Google Patents

Abstract

The present invention aims to provide an adhesive tape that can enable good adhesion of chip components when gripping the chip components and that can have excellent releasability to reduce adhesive deposits on the chip components when retransferring the chip components. Provided is an adhesive tape comprising at least one substrate layer and at least one adhesive layer, wherein the adhesive layer has a shear storage modulus G' of 1 MPa or less at a frequency of 10 Hz and -20 °C, and the adhesive tape has a surface peel strength to SUS of 0.5 MPa or less in an adhesive area of 10 mm × 10 mm.

Description

TECHNICAL AREA

The present invention relates to adhesive tapes.

STATE OF THE ART

The manufacturing process of semiconductor devices may involve transferring a large number of chip components arranged on an adhesive layer to a control board.

For example, micro-LED displays are display devices in which the individual chips that constitute the pixels are tiny light-emitting diode (LED) chips that emit light on their own to display images. Micro-LED displays are attracting attention as the next generation of display devices because they offer high contrast and fast response speed, and can be thinner because they do not require color filters used in display devices such as liquid crystal displays and organic EL displays. In micro-LED displays, a large number of micro-LED chips are densely arranged in a plane.

In the process for manufacturing such micro-LED displays or other semiconductor devices, for example, a transfer laminate in which a large number of chip components are arranged on an adhesive layer is positioned opposite to a drive board, and the chip components are separated from the transfer laminate to be electrically connected to the drive board (transfer step).

The transfer step may be performed multiple times. In other words, before the final transfer to the drive board, the chip components may be temporarily transferred to a carrier material for transportation or processing and then re-transferred from the carrier material to another carrier material or the drive board. An example of the carrier material is a transfer substrate disclosed in Patent Literature 1. The transfer substrate includes at least a substrate and a shock absorbing layer.

CITATION LIST

- Patent literature

Patent Literature 1: WO 2019/065441

SUMMARY OF THE INVENTION

- Technical problem

Since carrier materials must have the property of temporarily holding chip components, the use of adhesive tapes with adhesive layers as carrier materials was considered.

However, a conventional adhesive tape used as a carrier material may not work well for transferring chip components because the chip components may not adhere to the adhesive tape when the adhesive tape grips them. In addition, once the adhesive tape grips the chip components, it may not be able to separate the chip components when they are re-transferred to another carrier material or driver board. Even if the adhesive tape successfully separates the chip components, residues of the adhesive layer may remain on the chip components.

The present invention aims to provide an adhesive tape which can enable good adhesion of chip components when gripping the chip components and which can have excellent releasability to reduce adhesive deposits on the chip components when retransferring the chip components.

- The solution of the problem

The present disclosure 1 relates to an adhesive tape comprising at least one substrate layer and at least one adhesive layer, wherein the adhesive layer has a shear storage modulus G' of 1 MPa or less at a frequency of 10 Hz and -20 °C, and the adhesive tape has a surface peel strength to SUS of 0.5 MPa or less in an adhesive area of 10 mm × 10 mm.

The present disclosure 2 relates to the adhesive tape of the present disclosure 1, wherein the adhesive layer has a shear storage modulus G' of 0.3 MPa or less at a frequency of 10 Hz and -20 °C.

The present disclosure 3 relates to the adhesive tape of the present disclosure 1 or 2, wherein the adhesive layer has a shear storage modulus G' of 0.04 MPa or less at a frequency of 10 Hz and 23 °C.

The present disclosure 4 relates to the adhesive tape of the present disclosure 1, 2, or 3, wherein the adhesive layer has a thickness of 40 µm or more.

The present disclosure 5 relates to the adhesive tape of the present disclosure 1, 2, 3, or 4, which has a surface peel strength to SUS of 0.01 MPa or more in an adhesive area of 10 mm × 10 mm.

The present disclosure 6 relates to the adhesive tape of the present disclosure 1, 2, 3, 4 or 5, which has a surface peel strength to SUS of 0.2 MPa or less in an adhesive area of 10 mm × 10 mm.

The present disclosure 7 relates to the adhesive tape of the present disclosure 1, 2, 3, 4, 5 or 6, wherein the adhesive layer is an acrylic adhesive layer containing a (meth)acrylic polymer.

The present disclosure 8 relates to the adhesive tape of the present disclosure 7, wherein the (meth)acrylic polymer has a hydroxyl value of 45 mg KOH/g or lower.

The present disclosure 9 relates to the adhesive tape of the present disclosure 7 or 8, wherein the (meth)acrylic polymer contains 80 wt% or more of a structural unit derived from a (meth)acrylic acid ester (a) having a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer.

The present disclosure 10 relates to the adhesive tape of the present disclosure 9, wherein the (meth)acrylic polymer contains 40% by weight or more of a structural unit derived from a (meth)acrylic acid ester (a-1) which has an alkyl group with a carbon number of 12 or more and which has a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer.

The present disclosure 11 relates to the adhesive tape of the present disclosure 10, wherein the (meth)acrylic acid ester (a-1) which has an alkyl group with a carbon number of 12 or more and which has a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer contains lauryl (meth)acrylate.

The present disclosure 12 relates to the adhesive tape of the present disclosure 9, wherein the (meth)acrylic polymer contains 90 wt% or more of the structural unit derived from a (meth)acrylic acid ester (a) having a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer.

The present disclosure 13 relates to the adhesive tape of the present disclosure 7, 8, 9, 10, 11 or 12, wherein the (meth)acrylic polymer contains a structure derived from a monomer containing a hydroxyl group.

The present disclosure 14 relates to the adhesive tape of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13, wherein the adhesive layer is a photocurable adhesive layer.

The present disclosure 15 relates to the adhesive tape of the present disclosure 7, 8, 9, 10, 11, 12 or 13, wherein the (meth)acrylic polymer contains a carbon-carbon double bond in a side chain.

The present disclosure 16 relates to the adhesive tape of the present disclosure 15, wherein the (meth)acrylic polymer has a carbon-carbon double bond equivalent of 0.5 meq/g or less.

The present disclosure 17 relates to the adhesive tape of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 used in a step of transferring a component to grip the component.

The present disclosure 18 relates to the adhesive tape of the present disclosure 17, wherein the device is a semiconductor device.

The present invention will be described in detail below.

The present inventors have found that in an adhesive tape including at least one substrate layer and at least one adhesive layer, adjusting both the shear storage modulus G' of the adhesive layer at low temperature and the surface peel strength measured by a predetermined method to certain values or below results in an adhesive tape useful as a backing material. In other words, the present inventors have found that such an adhesive tape can enable good adhesion of chip components when gripping the chip components and can have excellent releasability to reduce adhesive deposits on the chip components when re-transferring the chip components. Thus, the inventors have completed the present invention.

1 is a schematic cross-sectional view illustrating an example of a step of transferring chip components arranged on an adhesive layer to an adhesive tape.

In the 1 In the step illustrated, chip components 1 arranged on an adhesive layer 4 laminated onto a substrate layer 5 are separated from the adhesive layer 4, for example by laser light irradiation. An adhesive tape 8 is a carrier material for holding the chip components 1 separated from the adhesive layer 4 and then transferring them back to another carrier material or a control board. The adhesive tape 8 includes a substrate layer 3 and an adhesive layer 2.

For example, a laminate 9 of the substrate layer 5 and the adhesive layer 4 may be a single-sided adhesive tape in which the substrate layer 5 is a substrate layer such as a resin film and the adhesive layer 4 is an adhesive layer, or may be a laminate of a carrier and a double-sided adhesive tape in which the substrate layer 5 is a carrier such as a glass substrate and the adhesive layer 4 is a double-sided adhesive tape (which may include a substrate).

The adhesive tape of the present invention comprises at least one substrate layer and at least one adhesive layer.

The presence of the substrate allows the adhesive tape of the present invention to have adequate rigidity and excellent handleability. The adhesive tape can thus serve as a carrier material that can grip or retransfer chip components.

There are no restrictions on the substrate. Examples of the substrate material include polyethylene terephthalate, polyethylene naphthalate, polyacetals, polyamides, polycarbonates, polyphenylene ethers, polybutylene terephthalate, ultra-high molecular weight polyethylene, syndiotactic polystyrene, polyarylates, polysulfones, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimides, polyetherimide, fluororesins, and liquid crystal polymers. Of these, polyethylene terephthalate and polyethylene naphthalate are preferred because they have excellent heat resistance.

There are no restrictions on the thickness of the substrate layer. The lower limit thereof is preferably 4 μm, and the upper limit thereof is 188 μm. When the thickness of the substrate layer is within the range, the adhesive tape can have adequate rigidity and excellent hand The lower limit of the thickness of the substrate layer is more preferably 50 µm, and the upper limit thereof is more preferably 125 µm. The lower limit is still more preferably 75 µm, and the upper limit is still more preferably 100 µm.

The upper limit of the shear storage modulus G' of the adhesive layer at a frequency of 10 Hz and -20 °C is 1 MPa.

The adhesive tape typically grips the chip components at a high speed. The shear storage modulus G' when force is applied at such a high speed is closely related to the shear storage modulus G' at a low temperature according to the temperature-rate superposition principle. The present inventors therefore investigated the shear storage modulus G' of the adhesive layer at a low temperature. With a shear storage modulus G' of 1 MPa or less at a frequency of 10 Hz and -20 °C, the adhesive layer can have improved damping when gripping chip components, so that the adhesive tape can enable good adhesion of chip components when gripping the chip components. The upper limit of the shear storage modulus G' at a frequency of 10 Hz and -20 °C is preferably 0.8 MPa, more preferably 0.5 MPa, and still more preferably 0.3 MPa.

The lower limit of the shear storage modulus G' at a frequency of 10 Hz and - 20 °C is not limited. In order to further improve the separability in the retransfer of chip components, the lower limit is preferably 0.05 MPa, more preferably 0.1 MPa.

The shear storage modulus G' of the adhesive layer at normal temperature is not limited. The upper limit of the shear storage modulus G' at a frequency of 10 Hz and 23 °C is preferably 0.1 MPa. With a shear storage modulus G' of 0.1 MPa or less at a frequency of 10 Hz and 23 °C, the adhesive tape can enable improved adhesion of chip components when gripping the chip components. The upper limit of the shear storage modulus G' at a frequency of 10 Hz and 23 °C is more preferably 0.04 MPa.

The lower limit of the shear storage modulus G' at a frequency of 10 Hz and 23 °C is not limited. In order to further improve the separability in the retransfer of chip components, the lower limit is preferably 0.01 MPa, more preferably 0.015 MPa.

For example, the shear storage modulus G' of the adhesive layer at -20 °C and 23 °C at a frequency of 10 Hz can be determined as the storage modulus at -20 °C and 23 °C when measuring a dynamic viscoelastic spectrum from -40 °C to 140 °C under the conditions of 10 Hz in a simple heating mode at a heating rate of 5 °C/min using a viscoelastic spectrometer (DVA-200, available from IT Keisoku Seigyo Co., Ltd.). When the adhesive layer is a curable adhesive layer, the shear storage modulus G' of the adhesive layer is the shear storage modulus G' measured for the adhesive layer before curing.

When the adhesive layer has a thickness of less than 100 µm, the adhesive layers are stacked to form an adhesive layer for measurement having a thickness of 100 µm or more. The shear storage modulus G' of the obtained adhesive layer for measurement is measured as described above.

The upper limit of the surface peel strength of the adhesive tape against SUS in an adhesive area of 10 mm × 10 mm is 0.5 MPa.

With a surface peel strength of 0.5 MPa or less, the adhesive tape does not have an excessively high adhesive force, so that the adhesive tape can have excellent releasability to reduce adhesive deposits on chip components in the retransfer of chip components. The upper limit of the surface peel strength is preferably 0.4 MPa, more preferably 0.2 MPa.

The lower limit of the surface peel strength is not limited. In order to further improve the property of holding chip components, the lower limit is preferably 0.005 MPa, more preferably 0.01 MPa.

2 is a schematic view illustrating a method for measuring the surface peel strength of an adhesive tape.

First, an adhesive tape 8 is cut to 10 mm × 10 mm. The adhesive layer of the cut adhesive tape 8 is attached to a SUS jig 12 (SUS304) and bonded under pressure at 0.3 MPa for 10 seconds. One surface of a double-sided adhesive tape 11 for measurement (available from Sekisui Chemical Co., Ltd., product name #560, or an equivalent product) is attached to the back of the adhesive tape 8 on the SUS jig 12. The other surface of the double-sided adhesive tape 11 for measurement is attached to a 5 mm thick glass plate 10. When the adhesive layer of the adhesive tape 8 is a curable adhesive layer, the adhesive layer is then cured, for example, by irradiating UV light from the side of the glass plate 10 with a UV lamp having a wavelength of 365 nm at an intensity of 10 mW/cm ² and a dose of 2,500 mJ/cm ² . In other words, when the adhesive layer is a curable adhesive layer, the surface peel strength of the adhesive tape means the surface peel strength measured for the adhesive tape after the adhesive layer is cured. Then, the glass plate 10 is attached to a tensile tester (available from Shimadzu Corporation, AGS-X or an equivalent product). A tensile test is performed by pulling the SUS frame 12 in the vertical direction (direction indicated by the arrow in the figure) at a peeling speed of 200 mm/min in an environment of a room temperature of 23 °C and a relative humidity of 50% using the tensile tester (available from Shimadzu Corporation, AGS-X or an equivalent product). The surface peel strength is thus measured. The surface peel strength means the maximum peel strength.

When the adhesive tape is a double-sided adhesive tape, the adhesive layer on the side opposite to the side for measuring the surface peel strength is attached and fixed to the glass plate. Apart from that, the surface peel strength is measured in the same way by a tensile tester. At this time, the adhesive layer of the adhesive tape on the side opposite to the side for measuring the surface peel strength can be directly attached and fixed to the glass plate, or can be attached via the double-sided adhesive tape 11 for measurement.

There are no restrictions on the thickness of the adhesive layer. The lower limit thereof is preferably 30 µm, and the upper limit thereof is preferably 200 µm. When the thickness is within the range, the adhesive layer can have better cushioning when the tape grips the chip components, so that the adhesive tape can enable better adhesion of the chip components when gripping the chip components. The lower limit of the thickness is more preferably 40 µm, and the upper limit thereof is more preferably 150 µm. The lower limit is still more preferably 70 µm, and the upper limit is still more preferably 100 µm.

The method for adjusting the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape to the above ranges is not limited. For example, they can be adjusted by adjusting factors such as composition, molecular weight (weight average molecular weight (Mw)), hydroxyl value and double bond equivalent of the base polymer in the adhesive layer or by adjusting the degree of crosslinking (gel fraction) of the adhesive layer.

The adhesive layer is not limited. Examples thereof include an acrylic adhesive layer, a rubber adhesive layer, a urethane adhesive layer, and a silicone adhesive layer. Of these, an acrylic adhesive layer containing a (meth)acrylic polymer is preferable because (meth)acrylic polymers can be easily adjusted in properties such as molecular weight and crosslinking degree, have excellent heat resistance and weather resistance, are inexpensive, and the like.

The (meth)acrylic polymer is a polymer having a structural unit derived from a (meth)acrylic monomer.

The (meth)acrylic monomer is not limited. Examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate. These (meth)acrylic monomers may be used alone or in combination of two or more of them.

Of these, preferred is a (meth)acrylic acid ester (a) which has a glass transition temperature (Tg) of 0°C or less when formed into a homopolymer (hereinafter also referred to simply as "(meth)acrylic acid ester (a)"). In other words, the (meth)acrylic polymer preferably contains a structural unit derived from the (meth)acrylic acid ester (a).

With the (meth)acrylic polymer including such a relatively flexible structural unit, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to the above-mentioned ranges, so that the adhesive tape can have higher releasability in retransferring chip components and enable better adhesion of the chip components in gripping the chip components. In particular, when the (meth)acrylic polymer includes such a relatively flexible structural unit and also the adhesive layer has a crosslinking degree (gel fraction) adjusted to an appropriate range, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges.

The glass transition temperature (Tg) of the (meth)acrylic acid ester (a) is not limited as long as it is 0 °C or less. In order to make the adhesive tape have even better releasability when retransferring chip components and enable even better adhesion of the chip components when gripping the chip components, the lower limit thereof is preferably -80 °C, the upper limit thereof is preferably -5 °C. The lower limit of the glass transition temperature (Tg) is more preferably -70 °C, and the upper limit thereof is more preferably -10 °C.

The glass transition temperature (Tg), when the (meth)acrylic acid ester is formed into a homopolymer, can be measured for a homopolymer having a weight average molecular weight (Mw) of about 5,000 to 1,000,000 or a degree of polymerization of about 50 to 10,000, for example, using a differential scanning calorimeter (available from TA Instruments).

Preferably, the (meth)acrylic acid ester (a) includes a (meth)acrylic acid ester (a-1) which has an alkyl group having a carbon number of 12 or more and which has a glass transition temperature (Tg) of 0°C or less when formed into a homopolymer (hereinafter also referred to simply as “(meth)acrylic acid ester (a-1)”). Also preferably, the (meth)acrylic acid ester (a) includes a (meth)acrylic acid ester (a-2) which has an alkyl group having a carbon number of 7 or more and less than 12 and which has a glass transition temperature (Tg) of 0°C or less when formed into a homopolymer (hereinafter also referred to simply as “(meth)acrylic acid ester (a-2)”).

When the (meth)acrylic polymer contains a structural unit having such an alkyl group with a relatively long carbon chain, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges.

In particular, the (meth)acrylic acid ester (a) more preferably includes both the (meth)acrylic acid ester (a-1) and the (meth)acrylic acid ester (a-2), because then the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to even more preferable ranges.

The (meth)acrylic acid ester (a-1) is not limited. Examples thereof among the above-mentioned (meth)acrylic monomers include lauryl acrylate (which has a Tg of -23°C when formed into a homopolymer) and lauryl methacrylate (which has a Tg of -65°C when formed into a homopolymer). Examples further include isomyristyl acrylate (which has a Tg of -56°C when formed into a homopolymer) and isostearyl acrylate (which has a Tg of -18°C when formed into a homopolymer). In particular, the (meth)acrylic acid ester (a-1) is preferably at least one selected from the group consisting of lauryl acrylate, lauryl methacrylate and isostearyl acrylate, since then the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges. Lauryl (meth)acrylate is more preferred, and lauryl acrylate is even more preferred.

The (meth)acrylic acid ester (a-2) is not limited. Examples thereof include heptyl acrylate (which has a Tg of -68°C when formed into a homopolymer), 2-ethylhexyl acrylate (which has a Tg of -70°C when formed into a homopolymer), and octyl acrylate (which has a Tg of -65°C when formed into a homopolymer). Further examples include isononyl acrylate (which has a Tg of -58°C when formed into a homopolymer) and isodecyl acrylate (which has a Tg of -62°C when formed into a homopolymer). In particular, the (meth)acrylic acid ester (a-2) is preferably at least one selected from the group consisting of heptyl acrylate and 2-ethylhexyl acrylate, since then the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges. 2-Ethylhexyl acrylate is even more preferred.

When the (meth)acrylic polymer contains the (meth)acrylic acid ester (a), the amount of a structural unit derived from the (meth)acrylic acid ester (a) in the (meth)acrylic polymer is not limited. The lower limit thereof is preferably 40 wt%. With an amount of the structural unit of 40 wt% or more, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher releasability in retransferring chip components and enable better adhesion of chip components in gripping the chip components. The lower limit of the amount of the structural unit is more preferably 45 wt%, more preferably 80 wt%, further preferably 90 wt%.

The upper limit of the amount of the structural unit is not limited. The upper limit is preferably 98 wt%, more preferably 95 wt%.

When the (meth)acrylic acid ester (a) includes the (meth)acrylic acid ester (a-1), the amount of a structural unit derived from the (meth)acrylic acid ester (a-1) in the (meth)acrylic polymer is not limited. The lower limit thereof is preferably 40 wt%. With an amount of the structural unit of 40 wt% or more, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher releasability in retransferring chip components and enable better adhesion of chip components in gripping the chip components. The lower limit of the amount of the structural unit is more preferably 45 wt%.

The upper limit of the amount of the structural unit is not limited. With too large an amount, the alkyl groups with long carbon chains (alkyl groups with a carbon number of 12 or more) present in the side chains may crystallize at low temperature, resulting in too high a shear storage modulus G' at a frequency of 10 Hz and -20 °C. Therefore, the upper limit is preferably 80 wt%, more preferably 70 wt%.

The (meth)acrylic polymer preferably further contains a structure derived from a monomer containing a crosslinkable functional group.

In the (meth)acrylic polymer having the structure derived from a monomer containing a crosslinkable functional group, the cohesive force of the adhesive layer can be adjusted by crosslinking the crosslinkable functional group, which makes it easy to adjust the adhesive force and the shear storage modulus G' of the adhesive layer. As a result, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher releasability in retransferring chip components and enable better adhesion of chip components in gripping the chip components. The crosslinkable functional group may be crosslinked or may be uncrosslinked, but is more preferably crosslinked. Even if the crosslinkable functional group remains uncrosslinked, interactions between functional groups can increase the cohesive force of the adhesive layer.

Examples of the monomer containing a crosslinkable functional group include monomers containing a group such as a carboxyl group, a hydroxyl group, an epoxy group, a double bond, a triple bond, an amino group, an amide group, or a nitrile group. These monomers containing crosslinkable functional groups may be used alone or in combination of two or more thereof. The monomer containing a crosslinkable functional group is preferably at least one selected from the group consisting of a monomer containing a carboxyl group and a monomer containing a hydroxyl group. A monomer containing a hydroxyl group is more preferable because the shear storage modulus G' of the adhesive layer can be easily adjusted by crosslinking the hydroxyl group by an isocyanate crosslinking agent.

The monomer containing a crosslinkable functional group may further contain a group such as an alkyl group, an ether group, a carbonyl group, an ester group, a carbonate group, an amide group or a urethane group.

Examples of the monomer containing a carboxyl group include (meth)acrylic acid monomers such as (meth)acrylic acid. Examples of the monomer containing a hydroxyl group include 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate. Examples of the monomer containing an epoxy group include glycidyl (meth)acrylate. Examples of the monomer containing a double bond include allyl (meth)acrylate and hexanediol di(meth)acrylate. Examples of the monomer containing a triple bond include propargyl (meth)acrylate. Examples of the monomer containing an amide group include (meth)acrylamide. Of these, 4-hydroxybutyl acrylate is preferred because it makes it easy to adjust the shear storage modulus G' of the adhesive layer to the above ranges.

The amount of the structure in the (meth)acrylic polymer derived from a monomer containing a crosslinkable functional group is not limited. For adjusting the adhesive force and the shear storage modulus G' of the adhesive layer, the lower limit of the amount of the structure is preferably 0.1 wt%, and the upper limit thereof is preferably 30 wt%. The lower limit of the amount of the structure is more preferably 0.5 wt%, and the upper limit thereof is more preferably 25 wt%.

The amount of a structure in the (meth)acrylic polymer derived from a monomer containing a hydroxyl group is not limited. For adjusting the adhesive force and the shear storage modulus G' of the adhesive layer, the lower limit of the amount of the structure is preferably 1 wt%, and the upper limit thereof is preferably 20 wt%. The lower limit of the amount of the structure is more preferably 3 wt%, and the upper limit thereof is more preferably 10 wt%.

The (meth)acrylic polymer may contain a carbon-carbon double bond in a side chain. The side chain means a branching portion extending from a main chain, the main chain being defined as the longest chain in the polymer.

When the (meth)acrylic polymer contains a carbon-carbon double bond in a side chain, the adhesive layer may be a curable adhesive layer that is cured by, for example, heating or light irradiation to greatly reduce the adhesive force. In such a case, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher releasability in retransferring chip components and enable better adhesion of chip components when gripping the chip components.

The curable adhesive layer may be, for example, a thermally curable adhesive layer or a photocurable adhesive layer. From the viewpoint of storage stability, a photocurable adhesive layer is preferred.

To obtain the (meth)acrylic polymer, a monomer mixture containing monomers such as the (meth)acrylic monomer and the monomer containing a crosslinkable functional group is radically reacted in the presence of a polymerization initiator for copolymerization.

When the acrylic polymer contains a carbon-carbon double bond in a side chain, the carbon-carbon double bond can be introduced into the side chain of the acrylic polymer, for example, by copolymerizing the monomer containing the double bond as the monomer containing a crosslinkable functional group. Alternatively, the monomer containing a crosslinkable functional group such as the monomer containing a carboxyl group or the monomer containing a hydroxyl group may be copolymerized, and then the obtained polymer may be reacted with a compound containing a double bond and a functional group reactive with the crosslinkable functional group such as a carboxyl group or a hydroxyl group in the polymer (hereinafter, the compound is also referred to as “unsaturated compound containing a functional group”). The unsaturated compound containing a functional group is not limited. Examples include unsaturated compounds containing an isocyanate group, such as 2-methacryloyloxyethyl isocyanate (MOI).

The radical reaction method for the monomer mixture, that is, the polymerization method, may be a conventionally known method such as solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization or bulk polymerization.

The hydroxyl value of the (meth)acrylic polymer is not limited. The upper limit thereof is preferably 45 mg KOH/g. With a hydroxyl value of 45 mg KOH/g or less, the adhesive force and the shear storage modulus G' of the adhesive layer can be easily adjusted. As a result, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher releasability in retransfer. of chip components and can enable better adhesion of chip components when gripping the chip components. The upper limit of the hydroxyl value is more preferably 20 mg KOH/g.

The lower limit of the hydroxyl number is not limited. For adjustments of the adhesive strength of the adhesive layer and the shear storage modulus G' of the adhesive tape, the lower limit is preferably 1 mg KOH/g.

The hydroxyl value of a (meth)acrylic polymer is an index of the content of hydroxyl groups in a certain amount of a sample. The hydroxyl value of a (meth)acrylic polymer refers to the number of milligrams of potassium hydroxide required to neutralize the acetic acid bound to hydroxyl groups by neutralization titration after 1 g of the (meth)acrylic polymer is acetylated. The hydroxyl value can be calculated by measurement based on potentiometric titration in accordance with JIS K 0070:1992.

The carbon-carbon double bond equivalent of the (meth)acrylic polymer is not limited. The upper limit thereof is preferably 0.5 mEq/g because too high a carbon-carbon double bond equivalent may result in too high a shear storage modulus G' at a frequency of 10 Hz and -20 °C. With a carbon-carbon double bond equivalent of 0.5 mEq/g or less, the shear storage modulus G' of the adhesive layer and the surface peel strength of the adhesive tape can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher separability when retransferring chip components and enable better adhesion of the chip components when gripping the chip components. The upper limit of the carbon-carbon double bond equivalent is more preferably 0.3 mEq/g.

The lower limit of the carbon-carbon double bond equivalent is not limited and can be 0 mEq/g.

The carbon-carbon double bond equivalent of the (meth)acrylic polymer refers to milliequivalents (mEq/g) of carbon-carbon double bonds of an unsaturated compound containing double bonds per gram of the (meth)acrylic polymer. The carbon-carbon double bond equivalent is a value calculated from the amounts of raw materials fed. Specifically, the carbon-carbon double bond equivalent E (mEq/g) can be calculated according to the following formula from the mass Wa (g) of the (meth)acrylic polymer, the molar amount nb (mol) of an unsaturated compound containing double bonds contained in the (meth)acrylic polymer, and the number N of carbon-carbon double bonds contained in a molecule of the unsaturated compound containing double bonds. $$\text{E}=\text{nb}\times \text{N}\times \text{1000/Wa}$$

The weight average molecular weight (Mw) of the (meth)acrylic polymer is not limited. The upper limit thereof is preferably 1,000,000. With a weight average molecular weight (Mw) of 1,000,000 or less, the shear storage modulus G' and the surface peel strength can be easily adjusted to more preferable ranges, so that the adhesive tape can have higher releasability when re-transferring chip components and enable better adhesion of the chip components when gripping the chip components. The upper limit of the weight average molecular weight (Mw) is more preferably 950,000, even more preferably 900,000.

The lower limit of the weight average molecular weight (Mw) is not limited. From the viewpoint of adhesive strength of the adhesive layer, shape retention and the like, the lower limit is preferably 400,000, more preferably 500,000.

The weight average molecular weight of the (meth)acrylic polymer can be determined by gel permeation chromatography (GPC), for example, as standard polystyrene. More specifically, the weight average molecular weight can be measured, for example, using “2690 Separations Module” available from Waters as a measuring instrument and “GPC KF-806L” available from Showa Denko K. K. as a column and ethyl acetate as a solvent under the conditions of a sample flow rate of 1 mL/min and a column temperature of 40 °C.

The adhesive layer may contain a tackifying resin.

Examples of the tackifying resin include rosin ester resins, hydrogenated rosin resins, terpene resins, terpene phenol resins, coumarone-indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, C9 petroleum resins, and C5-C9 copolymer petroleum resins. These tackifying resins may be used alone or in combination of two or more.

The amount of the tackifying resin is not limited. In order to achieve higher releasability in retransferring chip components, the adhesive layer preferably does not contain a tackifying resin. When the adhesive layer contains a tackifying resin, the upper limit of the amount thereof is preferably 10 parts by weight based on 100 parts by weight of a resin that is a main component of the adhesive layer (e.g., (meth)acrylic polymer). With an amount of the tackifying resin of 10 parts by weight or less, the adhesive layer can have higher releasability in retransferring chip components.

Preferably, the adhesive layer contains a cross-linking agent and thereby has a cross-linked structure formed between the main chains of the resins composing the adhesive layer (e.g. the (meth)acrylic polymer, the tackifying resin).

There are no restrictions on the crosslinking agent. Examples include isocyanate crosslinking agents, aziridine crosslinking agents, epoxy crosslinking agents, and metal chelate crosslinking agents. In particular, when the (meth)acrylic polymer contains the structural unit derived from a monomer containing hydroxyl groups, an isocyanate crosslinking agent is preferred because the shear storage modulus G' of the adhesive layer can be easily adjusted by crosslinking the hydroxyl group with the isocyanate crosslinking agent.

The amount of the crosslinking agent is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 7 parts by weight, based on 100 parts by weight of a resin which is a main component of the adhesive layer (e.g. the (meth)acrylic polymer).

If the adhesive layer is a curable adhesive layer, it may also contain a polymerization initiator, such as a thermal polymerization initiator or a photopolymerization initiator.

The amount of the polymerization initiator is not limited, but is preferably 0.01 part by weight or more and 5 parts by weight or less, more preferably 0.1 part by weight or more and 3 parts by weight or less, based on 100 parts by weight of the (meth)acrylic polymer.

The adhesive layer may also contain an inorganic filler such as fumed silica. The addition of the inorganic filler may increase the cohesive force of the adhesive layer.

The adhesive layer may further contain known additives such as a plasticizer, a resin, a surfactant, a wax and a fine particulate filler. These additives may be used alone or in combination of two or more thereof.

There are no restrictions on the gel fraction of the adhesive layer. The lower limit thereof is preferably 50 wt%, and the upper limit thereof is preferably 95 wt%. With a gel fraction of 50 wt% or more, the adhesive force of the adhesive layer can be adjusted to a relatively low range, so that the surface peel strength of the adhesive tape can be easily adjusted. As a result, the adhesive tape can have higher releasability when re-transferring chip components. With a gel fraction of 95 wt% or less, the shear storage modulus G' of the adhesive layer can be easily adjusted. As a result, the adhesive tape can enable better adhesion of chip components when gripping the chip components. The lower limit of the gel fraction is more preferably 80 wt%, and the upper limit thereof is more preferably 94 wt%. The lower limit is still more preferably 85 wt%, and the upper limit is still more preferably 93 wt%.

The gel fraction of the adhesive layer can be measured using the following method.

(W₀: das anfängliche Gewicht der Klebstoffzusammensetzung, W₁: das Gewicht der Klebstoffzusammensetzung einschließlich des Metallgitters nach dem Trocknen, W₂: das anfängliche Gewicht des Metallgitters)The adhesive layer (adhesive composition) alone is taken out of the adhesive tape in an amount of 0.1 g, immersed in 50 mL of ethyl acetate and shaken with a shaker at a temperature of 23 °C and 200 rpm for 24 hours. After shaking, a metal mesh (#200 mesh) is used to separate the ethyl acetate and the adhesive composition formed by the absorption of ethyl acetate. swollen. The separated adhesive composition is dried at 110 °C for one hour. The weight of the adhesive composition including the metal mesh is measured after drying, and the gel fraction of the adhesive layer is calculated using the following formula. When the adhesive layer is a curable adhesive layer, the gel fraction of the adhesive layer means the gel fraction measured for the adhesive layer before curing. $$\text{Gel fraction}\left(\text{Gew}\text{.-}\%\right)=\text{100}\times \left({\text{W}}_{\text{1}}-{\text{W}}_{\text{2}}\right)/{\text{W}}_0$$

(W ₀ : the initial weight of the adhesive composition, W ₁ : the weight of the adhesive composition including the metal grid after drying, W ₂ : the initial weight of the metal grid)

If the adhesive composition is not completely dissolved in ethyl acetate, a solvent such as toluene, hexane or water is used instead of ethyl acetate. Specifically, if the adhesive composition contains a styrene elastomer, for example, toluene or hexane is used. If the adhesive composition contains polyvinyl alcohol, hot water at 90 °C is used.

The adhesive tape of the present invention may be a single-sided adhesive tape having an adhesive layer on only one surface of a substrate layer or a double-sided adhesive tape having adhesive layers on both surfaces of a substrate layer.

Since the attachment of a support to the adhesive tape of the present invention improves the workability, the adhesive tape of the present invention is preferably a double-sided adhesive tape, more preferably a double-sided adhesive tape having adhesive layers on both surfaces of a substrate layer. The support is not limited. Examples thereof include glass, quartz substrates and metal plates.

When the adhesive tape of the present invention is a double-sided adhesive tape having adhesive layers on both surfaces of a substrate layer, the adhesive tape may have adhesive layers as described above on both surfaces, or may have an adhesive layer as described above on one surface and another adhesive layer on the other surface (surface to be attached to a support or the like). The different adhesive layer is not limited and may be a conventionally known adhesive layer.

The adhesive tape of the present invention can be used in any application. The adhesive tape is preferably used in a step of transferring a component to grip the component.

The component is not limited, but is preferably a semiconductor device. Examples of the semiconductor device include chip components such as micro-LED chips and optical chips of image sensors. Of these, micro-LED chips are preferable.

The adhesive tape of the present invention is particularly suitable as an adhesive tape for gripping chip components in a step of transferring chip components arranged on an adhesive layer to an adhesive tape, as in 1 The method for transferring chip components to the adhesive tape of the present invention is not limited. For example, chip components may be transferred by laser light irradiation. The method for re-transferring chip components from the adhesive tape of the present invention to another substrate or a driver board is not limited. For example, chip components may be re-transferred by directly laminating another substrate having adhesion and separating the adhesive tape, or by laser light irradiation.

- Advantageous effects of the invention

The present invention can provide an adhesive tape that can enable good adhesion of chip components when gripping the chip components and that can have excellent releasability to reduce adhesive deposits on the chip components when retransferring the chip components.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 is a schematic cross-sectional view illustrating an example of a step of transferring chip components arranged on an adhesive layer to an adhesive tape.
• 2 is a schematic view illustrating a method for measuring the surface peel strength of an adhesive tape.

DESCRIPTION OF EMBODIMENTS

The embodiments of the present invention are described in more detail below using examples, but are not limited to them.

(Example 1)

(1) Production of (meth)acrylic polymer

A reactor equipped with a thermometer, a stirrer and a condenser was filled with 52 parts by weight of ethyl acetate and purged with nitrogen. The reactor was then heated to start reflux. Thirty minutes after the ethyl acetate was boiled, 0.08 parts by weight of azo-bis-isobutyronitrile was added as a polymerization initiator. Then, 94.7 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of 2-hydroxybutyl acrylate and 0.3 parts by weight of acrylic acid were evenly and gradually dropped into the reactor over one and a half hours to carry out the reaction. Thirty minutes after the completion of the dropping, 0.1 part by weight of azo-bis-isobutyronitrile was added to carry out the polymerization reaction for another five hours, followed by cooling while adding ethyl acetate to the reactor for dilution. In this way, a solution of a (meth)acrylic polymer was obtained (hydroxyl number 24.2 mg KOH/g, double bond equivalent 0 mEq/g).

The weight-average molecular weight of the obtained (meth)acrylic polymer was measured using “2690 Separations Module” available from Waters as a measuring instrument and “GPC KF-806L” available from Showa Denko K. K. as a column and ethyl acetate as a solvent under the conditions of a sample flow rate of 1 mL/min and a column temperature of 40 °C. The weight-average molecular weight was 800,000.

(2) Production of an adhesive tape

Coronate L-45 (available from Tosoh Corporation) as an isocyanate crosslinking agent was added to the obtained solution of the (meth)acrylic polymer to a solid content of 1.8 parts by weight based on 100 parts by weight of the (meth)acrylic polymer, followed by sufficient stirring, thereby obtaining an adhesive solution. The obtained adhesive solution was applied to a 100 µm thick polyethylene terephthalate (PET) film as a substrate layer to a dry film thickness of 40 µm with an applicator and dried at 110 °C for 3 minutes to provide an adhesive tape.

(3) Measurement of the gel fraction

(W₀: das anfängliche Gewicht der Klebstoffzusammensetzung, W₁: das Gewicht der Klebstoffzusammensetzung einschließlich des Metallgitters nach dem Trocknen, W₂: das anfängliche Gewicht des Metallgitters)The adhesive layer (adhesive composition) alone was taken out of the adhesive tape in an amount of 0.1 g, immersed in 50 mL of ethyl acetate, and shaken with a shaker at a temperature of 23 °C and 200 rpm for 24 hours. After shaking, a metal mesh (#200 mesh) was used to separate the ethyl acetate and the adhesive composition swollen by the absorption of ethyl acetate. The separated adhesive composition was dried at 110 °C for 1 hour. The weight of the adhesive composition including the metal mesh was measured after drying, and the gel fraction of the adhesive layer was calculated using the following formula. When the adhesive layer is a curable adhesive layer, the gel fraction of the adhesive layer means the gel fraction measured for the adhesive layer before curing. $$\text{Gel fraction}\left(\text{Gew}\text{.-}\%\right)=\text{100}\times \left({\text{W}}_{\text{1}}-{\text{W}}_{\text{2}}\right)/{\text{W}}_0$$

(W ₀ : the initial weight of the adhesive composition, W ₁ : the weight of the adhesive composition including the metal grid after drying, W ₂ : the initial weight of the metal grid)

(4) Measurement of the shear storage modulus G'

The adhesive layer was subjected to dynamic viscoelastic spectrum measurement from -40 °C to 140 °C under the conditions of 10 Hz in a simple heating mode at a heating rate of 5 °C/min using a viscoelastic spectrometer (DVA-200, available from IT Keisoku Seigyo Co., Ltd.). The storage modulus G' at -20 °C and 23 °C at a frequency of 10 Hz was determined. When the adhesive layer is a curable adhesive layer, the shear storage modulus G' of the adhesive layer is the shear storage modulus G' measured for the adhesive layer before curing.

(5) Measurement of surface peel strength (bonding area 10 mm × 10 mm, versus SUS)

2 is a schematic view illustrating a method for measuring the surface peel strength of an adhesive tape. First, an adhesive tape 8 was cut to 10 mm × 10 mm. The adhesive layer of the cut adhesive tape 8 was attached to a SUS jig 12 (SUS304), and bonded under pressure at 0.3 MPa for 10 seconds. One surface of the double-sided adhesive tape 11 for measurement (available from Sekisui Chemical Co., Ltd., product name #560) was attached to the SUS jig 12 on the back of the adhesive tape 8. The other surface of the double-sided adhesive tape 11 for measurement was attached to a 5 mm thick glass plate 10. Then, the glass plate 10 was attached to a tensile tester (available from Shimadzu Corporation, AGS-X). Here, when measuring the surface peel strength of the adhesive tape 8 after UV irradiation, the adhesive layer was peeled off, for example. For example, the adhesive layer of the adhesive tape 8 was cured by irradiating the adhesive layer of the adhesive tape 8 with UV light from the side of the glass plate 10 using a UV lamp of wavelength 365 nm at an intensity of 10 mW/cm ² and a dose of 2,500 mJ/cm ² before the glass plate 10 was attached to the tensile tester. A tensile test was conducted by pulling the SUS rack 12 in the vertical direction (direction indicated by the arrow in the figure) at a peeling speed of 200 mm/min in an environment at a room temperature of 23 °C and a relative humidity of 50% by using the tensile tester (available from Shimadzu Corporation, AGS-X). In this way, the surface peel strength of the adhesive tape was measured. Here, the surface peel strength means the maximum peel strength.

(Examples 2 to 9 and 13 to 16 and comparative examples 1 to 3 and 5)

An adhesive tape was obtained as in Example 1, except that factors such as the composition and weight-average molecular weight of the (meth)acrylic polymer, the type and amount of the crosslinking agent, and the thickness of the adhesive layer were changed as shown in Table 1 or 2. As the crosslinking agent, Coronate HX (available from Tosoh Corporation), which is an isocyanate crosslinking agent, and Tetrad C (available from Mitsubishi Gas Chemical Company, Inc.), which is an epoxy crosslinking agent, were also used.

(Examples 10 to 12 and comparative examples 4, 6, and 7)

A solution of a (meth)acrylic polymer was obtained as in Example 1, except that factors such as the composition and weight-average molecular weight of the (meth)acrylic polymer were changed as shown in Table 1 or 2.

2-Methacryloyloxyethyl isocyanate (MOI) as an unsaturated compound containing an isocyanate group was added in an amount shown in Table 1 or 2 based on 100 parts by weight of the resin solid content of the obtained solution containing a (meth)acrylic polymer, and the addition reaction was carried out at 60 °C for two hours to prepare a solution of a (meth)acrylic polymer containing a carbon-carbon double bond in a side chain.

Subsequently, an adhesive tape was obtained as in Example 1, except that factors such as the type and amount of the crosslinking agent and the thickness of the adhesive layer were changed as shown in Tables 1 to 2, and that Omnirad 651 (available from IGM Resins B.V.), which is a photopolymerization initiator, was added in an amount shown in Table 1 or 2.

<Rating>

The adhesive tapes obtained in the examples and comparative examples were evaluated by the following methods. The results are shown in Tables 1 and 2.

(1) Assessment of the property of transfer of chip components (liability of chip components)

In addition to the adhesive tape received, a single-sided test adhesive tape was also provided.

A wafer was prepared on which 10 Si chips (500 µm × 500 µm square, thickness 50 µm) were arranged. The single-sided test tape was attached to the Si chip-side surface of the wafer. The wafer was then removed to arrange the Si chips on the single-sided test tape.

The test single-sided adhesive tape with the Si chips arranged was positioned opposite to the adhesive tape obtained in an example or comparative example. The individual Si chips were irradiated with laser light of wavelength 365 nm from the substrate layer side of the test single-sided adhesive tape using a semiconductor solid-state laser with an output of 4 W and 4 KHz to separate the Si chips and transfer them to the adhesive tape. The chip component transfer property was evaluated as follows. "○○" (very good): 10 Si chips adhered to the adhesive tape when the adhesive tape gripped the Si chips. "○" (good): 8 or 9 Si chips adhered to the adhesive tape, "×" (poor): 7 or less Si chips adhered to the adhesive tape.

(2) Retransfer property and adhesive deposition after retransfer

A wafer on which 10 Si chips (500 µm × 500 µm square, thickness 50 µm) were arranged was provided. The resulting adhesive tape was attached to the Si chip-side surface of the wafer. The wafer was then removed to arrange the Si chips on the adhesive tape. In Examples 10 to 12 and Comparative Examples 4, 6 and 7 in which the adhesive layer was a curable adhesive layer (photocurable adhesive layer), the adhesive layer was cured by irradiating UV light from the substrate layer side with a UV lamp having a wavelength of 365 nm at an intensity of 10 mW/cm ² and a dose of 2,500 mJ/cm ² .

The adhesive tape with the Si chips arranged was positioned opposite to an adhesive surface of a protective tape (6312C, available from Sekisui Chemical Co., Ltd.), and they were pressure-bonded with a 2 kg roller at a speed of 300 mm/min to bond the Si chips to the protective tape under pressure. The protective tape was separated to separate the Si chips from the adhesive tape and transfer them back to the protective tape. The retransfer property was evaluated as follows. "○○" (very good): 10 Si chips were arranged from the adhesive tape to the protective tape. "○" (good): 8 or 9 Si chips were arranged on the protective tape. "×" (poor): 7 or less Si chips were arranged on the protective tape.

[Tabelle 1] Vergleichsbeispiel 1 Vergleichsbeispiel 2 Vergleichsbeispiel 3 Vergleichsbeispiel 4 Vergleichsbeispiel 5 Vergleichsbeispiel 6 Vergleichsbeispiel 7 Zusammensetzung der Klebeschicht (Gewichtsteile) (Meth)acrylpolymer BA 947 - - - 98 - - HPA - - - - - - - 2-EHA - 89,7 49,7 81 - - 88,7 LA - - 45 - - 89,7 - 2-HEA - 10 - 18 - 10 11 4-HBA 5 - 5 - - - - AAc 0,3 0,3 0,3 1 2 0,3 0,3 AAm - - - - - - - Ungesättigte Verbindung, die Isocyanatgruppen enthält (MOI) - - - 8 - 12 12 Vernetzungsmittel Coronate L 0,8 0,8 0,01 0,1 - 0,2 0,2 Coronate HX - - - - - - - Tetrad C - - - - 0,25 - - Photopolymerisationsstarter Omnirad 651 - - - 1 - 3 3 (Meth)acrylpolymer Hydroxylzahl [mg KOH/g] 24,2 48,3 19,5 58,0 0 4,4 8,7 Kohlenstoff-Kohlenstoff-Doppelbindungsäquivalent [mÄq/g] 0 0 0 0,52 0 0,69 0,69 Mw [× 10⁴] 84 81 78 72 81 80 75 Klebeschicht Gelanteil [Gew.-%] 88 88 32 55 85 75 72 Scherspeichermodul bei -20 °C [MPa] 1,08 1,05 0,16 4,7 1,47 80,2 8,1 Scherspeichermodul bei -23 °C [MPa] 0,114 0,059 0,032 0,061 0,081 0,031 0,065 Dicke [µm] 75 75 75 75 75 75 75 Klebeband Oberflächenschälfestigkeit [MPa] Vor UV-Bestrahlung 0,48 0,44 0,65 0,75 0,95 0,44 0,45 Nach UV-Bestrahlung 0,48 0,44 0,65 0,18 0,95 0,15 0,15 Bewertung Eigenschaft Übertragung Chipkomponetne × × ○ × × × × Klebstoffablagerung nach Rückübertragung ○ ○ × ○ × ○ ○ Rückübertragungseigenschaft ○ ○ × ○ × ○ ○ [Tabelle 2]Further, the surfaces of the Si chips separated from the adhesive tape were observed with a microscope, and the adhesive deposits were evaluated as follows. "○" (good): no adhesive deposit was observed. "×" (poor): adhesive deposit was observed.

[Table 1] Comparison example 1 Comparison example 2 Comparison example 3 Comparison example 4 Comparison example 5 Comparison example 6 Comparison example 7 Composition of the adhesive layer (parts by weight) (Meth)acrylic polymer BA 947 - - - 98 - - HPA - - - - - - - 2-EHA - 89.7 49.7 81 - - 88.7 LA - - 45 - - 89.7 - 2-HEA - 10 - 18 - 10 11 4-HBA 5 - 5 - - - - AAc 0.3 0.3 0.3 1 2 0.3 0.3 AAm - - - - - - - Unsaturated compound containing isocyanate groups (MOI) - - - 8th - 12 12 Crosslinking agents Coronate L 0.8 0.8 0.01 0.1 - 0.2 0.2 Coronate HX - - - - - - - Tetrad C - - - - 0.25 - - Photopolymerization initiator Omniwheel 651 - - - 1 - 3 3 (Meth)acrylic polymer Hydroxyl number [mg KOH/g] 24.2 48.3 19.5 58.0 0 4.4 8.7 Carbon-carbon double bond equivalent [mEq/g] 0 0 0 0.52 0 0.69 0.69 Mw [× 10 ⁴ ] 84 81 78 72 81 80 75 Adhesive layer Gel content [wt.%] 88 88 32 55 85 75 72 Shear storage modulus at -20 °C [MPa] 1.08 1.05 0.16 4.7 1.47 80.2 8.1 Shear storage modulus at -23 °C [MPa] 0.114 0.059 0.032 0.061 0.081 0.031 0.065 Thickness [µm] 75 75 75 75 75 75 75 duct tape Surface peel strength [MPa] Before UV irradiation 0.48 0.44 0.65 0.75 0.95 0.44 0.45 After UV irradiation 0.48 0.44 0.65 0.18 0.95 0.15 0.15 Evaluation Property Transmission Chip Component × × ○ × × × × Adhesive deposit after retransfer ○ ○ × ○ × ○ ○ Retransmission property ○ ○ × ○ × ○ ○ [Table 2]

• BA: Butyl acrylate
• HPA: Heptyl Acrylate
• 2-EHA: 2-Ethylhexyl acrylate
• LA: Lauryl acrylate
• 2-HEA: 2-hydroxyethyl acrylate
• 4-HBA: 4-hydroxybutyl acrylate
• AAc: acrylic acid
• AAm: Acrylamide

INDUSTRIAL APPLICABILITY

The present invention can provide an adhesive tape that can enable good adhesion of chip components when gripping the chip components and that can have excellent releasability to reduce adhesive deposits on the chip components when retransferring the chip components.

LIST OF REFERENCE SYMBOLS

1

Chip component

2

Adhesive layer

3

Substrate layer

4

Adhesive layer

5

Substrate layer

8th

duct tape

9

Laminate of substrate layer and adhesive layer

10

Glass plate

11

Double-sided adhesive tape for measurement

12

SUS frame

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2019065441 [0006]

Claims (18)

Adhesive tape comprising at least one substrate layer and at least one adhesive layer, characterized in that the adhesive layer has a shear storage modulus G' of 1 MPa or less at a frequency of 10 Hz and -20 °C, and the adhesive tape has a surface peel strength to SUS of 0.5 MPa or less in an adhesive area of 10 mm × 10 mm. Adhesive tape after Claim 1 , characterized in that the adhesive layer has a shear storage modulus G' of 0.3 MPa or less at a frequency of 10 Hz and -20 °C. Adhesive tape after Claim 1 or 2 , characterized in that the adhesive layer has a shear storage modulus G' of 0.04 MPa or less at a frequency of 10 Hz and 23 °C. Adhesive tape after Claim 1 , 2 or 3 , characterized in that the adhesive layer has a thickness of 40 µm or more. Adhesive tape after Claim 1 , 2 , 3 or 4 , characterized in that it has a surface peel strength to SUS of 0.01 MPa or more in an adhesive area of 10 mm × 10 mm. Adhesive tape after Claim 1 , 2 , 3 , 4 or 5 , characterized in that it has a surface peel strength to SUS of 0.2 MPa or less in an adhesive area of 10 mm × 10 mm. Adhesive tape after Claim 1 , 2 , 3 , 4 , 5 or 6 , characterized in that the adhesive layer is an acrylic adhesive layer containing a (meth)acrylic polymer. Adhesive tape after Claim 7 , characterized in that the (meth)acrylic polymer has a hydroxyl number of 45 mg KOH/g or lower. Adhesive tape after Claim 7 or 8th , characterized in that the (meth)acrylic polymer contains 80 wt.% or more of a structural unit derived from a (meth)acrylic acid ester (a) which has a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer. Adhesive tape after Claim 9 , characterized in that the (meth)acrylic polymer contains 40 wt.% or more of a structural unit derived from a (meth)acrylic acid ester (a-1) which has an alkyl group with a carbon number of 12 or more and which has a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer. Adhesive tape after Claim 10 , characterized in that the (meth)acrylic acid ester (a-1) which has an alkyl group with a carbon number of 12 or more and has a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer contains lauryl (meth)acrylate. Adhesive tape after Claim 9 , characterized in that the (meth)acrylic polymer contains 90 wt.% or more of a structural unit derived from a (meth)acrylic acid ester (a) which has a glass transition temperature (Tg) of 0 °C or lower when formed into a homopolymer. Adhesive tape after Claim 7 , 8th , 9 , 10 , 11 or 12 , characterized in that the (meth)acrylic polymer contains a structure derived from a monomer containing a hydroxyl group. Adhesive tape after Claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8th , 9 , 10 , 11 , 12 or 13 , characterized in that the adhesive layer is a photocurable adhesive layer. Adhesive tape after Claim 7 , 8th , 9 , 10 , 11 , 12 or 13 , characterized in that the (meth)acrylic polymer contains a carbon-carbon double bond in a side chain. Adhesive tape after Claim 15 , characterized in that the (meth)acrylic polymer has a carbon-carbon double bond equivalent of 0.5 mEq/g or less. Adhesive tape after Claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8th , 9 , 10 , 11 , 12 , 13 , 14 , 15 or 16 , characterized in that it is used in a step of transferring a component to grasp the component. Adhesive tape after Claim 17 , characterized in that the component is a semiconductor component.

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