Adhesive agent and multilayer structure

Abstract

To provide a novel adhesive agent suitable for a cutting-edge wafer process.SOLUTION: An adhesive agent contains polyimide, and polyimide is a reaction product of reactant (a) and reactant (b). The reactant (a) is first diamine, or the reactant (a) consists of first diamine and second diamine, the reactant (b) consists of first dianhydride and second dianhydride. The first diamine is diamine containing a diphenyl ether part, the first dianhydride is dianhydride containing a diphenyl ether part, the second diamine is not diamine containing a diphenyl ether part, and the second dianhydride is not dianhydride containing a diphenyl ether part. The total weight percentage of the first diamine and the first dianhydride for the total weight of the reactant (a) and the reactant (b) is 55wt% to 94wt%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to adhesives and multilayer structures.

Background Art

[0002] Advanced wafer processes are aimed at miniaturization and finer linewidth processes. In order to avoid problems such as the formation of fragments and residues during wafer processing, it is necessary to enhance the dimensional stability and temperature resistance of the adhesive material used to temporarily protect the wafer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventional temporary wafer protection materials include acrylic adhesives and polyamic acid adhesives. Acrylic adhesives have low heat resistance (≦150°C), which is disadvantageous for semiconductor processes, and their more flexible nature makes it easy to leave residues on the sidewalls of electrodes. Polyamic acid adhesives require a two-step process of applying a polyamic acid material to a substrate and then closing the polyamic acid ring by high-temperature (300°C or higher) treatment to form a polyimide film. However, such high processing temperatures can cause large stresses due to the difference in the thermal expansion coefficients of the polyimide and the substrate, which may cause warping, deformation, cracking, and ultimately delamination of the substrate, and damage to the device.

[0005] Therefore, a new adhesive material suitable for advanced wafer processes is needed.

Means for Solving the Problems

[0006] The present disclosure provides an adhesive. The adhesive contains a polyimide. The polyimide is a reaction product of a reactant (a) and a reactant (b). The reactant (a) is a first diamine or the reactant (a) consists of a first diamine and a second diamine. The reactant (b) consists of a first dianhydride and a second dianhydride. The first diamine is a diamine containing a diphenyl ether moiety. The first dianhydride is a dianhydride containing a diphenyl ether moiety. The second diamine is not a diamine containing a diphenyl ether moiety. The second dianhydride is not a dianhydride containing a diphenyl ether moiety. The total weight percentage of the first diamine and the first dianhydride is from 55 wt% to 94 wt% based on the total weight of the reactant (a) and the reactant (b).

[0007] According to an embodiment of the present disclosure, the present disclosure provides a multilayer structure including a first substrate and an adhesive layer disposed on the first substrate, wherein the adhesive layer is a cured product of the disclosed adhesive.

Advantages of the Invention

[0008] The present disclosure provides an adhesive and a multilayer structure. For example, the adhesive can be removed by laser light without leaving residues. The multilayer structure includes an adhesive layer made from the adhesive of the present disclosure. According to an embodiment of the present disclosure, the adhesive of the present disclosure contains polyimide. The polyimide can be obtained by reacting a specific diamine (for example, a diamine containing a diphenyl ether moiety) as reactant (a) with a specific dianhydride (for example, a dianhydride containing a diphenyl ether moiety and a dianhydride not containing a diphenyl ether moiety) as reactant (b). By controlling the total weight of the diamine containing a diphenyl ether moiety and the dianhydride containing a diphenyl ether moiety with respect to the total weight of reactant (a) and reactant (b) to satisfy a specific relationship, the glass transition temperature (Tg) of the polyimide of the present disclosure can be made to be in the range from 180°C to 245°C, and the UV transmittance at wavelengths from 260 nm to 355 nm can be made 5% or less. As a result, the adhesive containing the polyimide of the present disclosure can bond a first substrate (for example, a transparent support) and a second substrate (for example, an electronic element) at a lower processing temperature (for example, 300°C or lower), and warping of the substrate caused by high-temperature processing can be avoided. Furthermore, since the adhesive of the present disclosure can absorb UV light (that is, has a low UV transmittance), the first substrate and the second substrate can be separated by irradiating the adhesive with laser light. Therefore, it becomes possible to separate the electronic element from the substrate during processing or rework, and no residue of the adhesive remains.

Brief Description of the Drawings

[0009] The present disclosure can be more fully understood by reading the following detailed description and examples with reference to the accompanying drawings.

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0010] The adhesives and multilayer structures of the present disclosure are described in detail in the following detailed description. In the following detailed description, for the purpose of explanation, numerous specific details and embodiments are set forth so that the present disclosure may be thoroughly understood. The specific elements and configurations in the following detailed description are presented to more clearly illustrate the present disclosure. However, it will be apparent that the exemplary embodiments shown herein are for illustrative purposes only and that the inventive concept may be embodied in various forms without being limited to these exemplary embodiments. In addition, for the purpose of more clearly explaining the present disclosure, in the figures of different embodiments, similar and / or corresponding numerals may be used to indicate similar and / or corresponding elements. However, the use of similar and / or corresponding numerals in the figures of different embodiments does not imply any correlation between the different embodiments. As used herein, the term "about" in terms of quantity indicates plus or minus by an amount that is common and reasonable to those skilled in the art.

[0011] Also, the use of terms such as "first", "second", "third", etc. to denote an order for modifying elements in the present disclosure does not in itself imply any priority, precedence, order, or temporal order of formation of one element over another in a claim, but is merely used as a label to distinguish one element of a claim having a particular name from another element having the same name (in the absence of the use of terms denoting order) and serves only to distinguish the elements of the claims from each other.

[0012] It should be noted that the elements or devices in the drawings of the present disclosure may exist in any form or configuration known to those skilled in the art. Further, the expressions "a layer covering another layer", "a layer is disposed above another layer", "a layer is disposed on another layer", and "a layer is disposed over another layer" may refer to a layer in direct contact with another layer, and they may also refer to a layer in which one or more intermediate layers are disposed between it and another layer and which is not in direct contact with another layer.

[0013] The disclosed figures are only schematic and non-limiting. In the figures, for the purpose of illustration, the sizes, shapes or thicknesses of some elements may be exaggerated and not drawn to scale. Dimensions and relative dimensions do not correspond to the actual positions of the implementation of the present disclosure. The present disclosure is described with reference to specific embodiments and specific drawings, but the present disclosure is not limited thereto.

[0014] According to an embodiment of the present disclosure, the present disclosure provides an adhesive, and the adhesive contains polyimide. According to an embodiment of the present disclosure, the polyimide may be a reaction product of reactant (a) and reactant (b), reactant (a) may be a first diamine, or reactant (a) may be composed of a first diamine and a second diamine. Reactant (b) consists of a first dianhydride and a second dianhydride. According to an embodiment of the present disclosure, the first diamine may be a diamine containing a diphenyl ether moiety, and the first dianhydride may be a dianhydride containing a diphenyl ether moiety. The diphenyl ether moiety may have any of the following structures.

[0015]

Chemical formula

[0016] Among the hydrogens bonded to the carbon of the above part, at least one may be optionally substituted with fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group. The second diamine does not contain a diphenyl ether moiety (i.e., the first diamine and the second diamine are different), and the second dianhydride does not contain a diphenyl ether moiety (i.e., the first dianhydride and the second dianhydride are different). It should be noted that the glass transition temperature (Tg) of the polyimide of the present disclosure can be in the range of 180°C to 245°C (for example, 190°C, 200°C, 210°C, 220°C, 230°C or 240°C), and the UV transmittance at wavelengths from 260 nm to 355 nm is 5% or less (for example, 4%, 3%, 2% or 1%). According to an embodiment of the present disclosure, based on the total weight of reactant (a) and reactant (b), the total weight percentage of the first diamine and the first dianhydride is in the range of 55 wt% to 94 wt% (for example, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt% or 93 wt%). When the weights of the first diamine and the first dianhydride are controlled within the above range, the glass transition temperature (Tg) of the polyimide of the present disclosure can be in the range between 180°C and 245°C, and the UV transmittance at wavelengths from 260 nm to 355 nm is 5% or less.

[0017] According to an embodiment of the present disclosure, when the reactant (a) is a first diamine and the reactant (b) consists of a first dianhydride and a second dianhydride, the amount of the second dianhydride may be in the range of 6 wt% to 45 wt% with respect to the total weight of the reactant (a) and the reactant (b) (i.e., all dianhydrides and diamines used to produce the polyimide). According to an embodiment of the present disclosure, when the reactant (a) consists of a first diamine and a second diamine and the reactant (b) consists of a first dianhydride and a second dianhydride, the total weight percentage of the second diamine and the second dianhydride may also be in the range of 6 wt% to 45 wt% with respect to the total weight of the reactant (a) and the reactant (b).

[0018] According to an embodiment of the present disclosure, the first dianhydride may be at least one of the dianhydrides having a structure represented by formula (I).

[0019]

Chemical formula

[0020] In the formula, R 1 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, a is independently 0, 1, 2 or 3, and A 1 is -O-,

Chemical formula

[0021] According to an embodiment of the present disclosure, the first dianhydride may be any one of the following, or a combination thereof.

[0022] [Chemical formula] [Chemical formula]

[0023] In the formula, R 1 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, a is independently 0, 1, 2 or 3, R 2 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, b is independently 0, 1, 2, 3 or 4, R 3 is independently hydrogen, fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, R 4 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, and c is independently 0, 1, 2, 3, 4, 5 or 6.

[0024] According to an embodiment of the present disclosure, the first diamine may be at least one of the diamines having the structure represented by formula (II).

[0025] [Chemical formula]

[0026] In the formula, R5 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, d is independently 0, 1, 2, 3 or 4, and A 2 is -O-,

Chemical formula

[0027] According to an embodiment of the present disclosure, the first diamine may be any of the following, or a combination thereof.

[0028]

Chemical formula

Chemical formula

Chemical formula

[0029] In the formula, R 5 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, d is independently 0, 1, 2, 3 or 4, and R 6is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, e is independently 0, 1, 2, 3 or 4, R 7 is independently hydrogen, fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, R 8 is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, f is independently 0, 1, 2, 3, 4, 5 or 6.

[0030] According to an embodiment of the present disclosure, the alkyl group of the present disclosure may be linear or branched. According to an embodiment of the present disclosure, the C1-C4 alkyl group may be methyl, ethyl, propyl, butyl, or isomers thereof. For example, the C1-C4 alkyl group of the present disclosure may be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, iso-butyl, or tert-butyl.

[0031] According to an embodiment of the present disclosure, the C1-C4 alkoxy group of the present disclosure may be linear or branched. For example, the C1-C4 alkoxy group may be methoxy, ethoxy, propoxy, butoxy, or isomers thereof.

[0032] According to an embodiment of the present disclosure, the C1-C4 fluoroalkyl group may be an alkyl group in which some or all of the hydrogen atoms bonded to the carbon atoms are substituted with fluorine atoms. The C1-C4 fluoroalkyl group may be linear or branched, for example, fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, or isomers thereof. Here, the fluoromethyl group may be a monofluoromethyl group, a difluoromethyl group or a trifluoromethyl group, and the fluoroethyl may be a monofluoroethyl group, a difluoroethyl group, a trifluoroethyl group, a tetrafluoroethyl, or a perfluoroethyl.

[0033] According to an embodiment of the present disclosure, the C1-C4 fluoroalkoxy group of the present disclosure may be linear or branched. For example, the C1-C4 fluoroalkoxy group may be fluoromethoxy, fluoroethoxy, fluoropropoxy, fluorobutoxy, or an isomer thereof. Here, the fluoromethoxy group may be a monofluoromethoxy group, a difluoromethoxy group, or a trifluoromethoxy group, and fluoroethoxy may be a monofluoroethoxy group, a difluoroethoxy group, a trifluoroethoxy group, tetrafluoroethoxy, or perfluoroethoxy.

[0034] According to an embodiment of the present disclosure, the second dianhydride is different from the first dianhydride. The second dianhydride may be a dianhydride that does not contain a diphenyl ether moiety. According to an embodiment of the present disclosure, the second dianhydride may not consist of cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), or the second dianhydride may not consist of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA).

[0035] According to an embodiment of the present disclosure, the second dianhydride may be an aromatic dianhydride or an aliphatic dianhydride. According to an embodiment of the present disclosure, the second dianhydride is bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (B1317), bicyclooctane tetracarboxylic dianhydride (BODA), dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (H-BPDA), [3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride] (TCA-AH), 1,2,3,4-butanetetracarboxylic dianhydride (BDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (4,4'-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (3,4'-BPDA), 5-[4-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione (1,4-PIB), 5-[3-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione (1,3-PIB), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), or a combination thereof.

[0036] According to an embodiment of the present disclosure, when the second dianhydride includes cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) or 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA), the second dianhydride may further include bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (B1317), bicyclooctanetetracarboxylic dianhydride (BODA), dicyclohexyl-3,4,3’,4’-tetracarboxylic dianhydride (H-BPDA), [3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride] (TCA-AH), 1,2,3,4-butanetetracarboxylic dianhydride (BDA), 3,3’,4,4’-biphenyltetracarboxylic dianhydride (4,4’-BPDA), 2,3,3’,4’-biphenyltetracarboxylic dianhydride (3,4’-BPDA), 5-[4-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione (1,4-PIB), 5-[3-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione (1,3-PIB), 4,4’-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 3,3’,4,4’-benzophenonetetracarboxylic dianhydride (BTDA), 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), or a combination thereof.

[0037] According to an embodiment of the present disclosure, the second diamine is different from the first diamine. The second diamine may be a diamine that does not include a diphenyl ether moiety. According to an embodiment of the present disclosure, the second diamine does not consist of isophoronediamine (IPDA), or the second diamine does not consist of 4-methylcyclohexane-1,3-diamine (HTDA).

[0038] According to an embodiment of the present disclosure, the second diamine may be an aromatic diamine or an aliphatic diamine. According to an embodiment of the present disclosure, the second diamine is 4,4'-methylenebis(cyclohexylamine) (PACM), 4,4'-methylenebis(2-methylcyclohexylamine) (MACM), bis(aminomethyl)norbornane (NORB), adamantane-1,3-diamine (ADDA), octahydro-4,7-methanoinden-1(2),5(6)-dimethanamine, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4,4'-diamino-2,2'-dimethylbiphenyl (m-TBHG), O-tolidine, 4,4'-methylenedianiline (4,4'-DAPM), 3,4'-methylenedianiline (3,4'-DAPM), 4,4'-diamino-3,3'-dimethyldiphenylmethane (MDA), 4,4'-methylenebis(2-ethylbenzeneamine) (MOEA), 4,4'-methylenebis(2,6-diethylaniline) (MDEA), 9,10-bis(4-aminophenyl)anthracene (ADA), 2,6-naphthalenediamine, 2,6-anthracenediamine, 4,4''-diamino-p-terphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane (AAF), α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene (bisaniline P), 9,9-bis(4-aminophenyl)fluorene (FDA), 3,3',5,5'-tetramethylbenzidine (TMB), 4,4'-diamino-2,2'-dimethoxybiphenyl (m-DS), 4,4'-diaminobenzophenone (DABP), or a combination thereof.

[0039] According to an embodiment of the present disclosure, when the second diamine does not consist of isophoronediamine (IPDA) or the second diamine does not consist of 4-methylcyclohexane-1,3-diamine (HTDA), the second diamine may include 4,4'-methylenebis(cyclohexylamine) (PACM), 4,4'-methylenebis(2-methylcyclohexylamine) (MACM), bis(aminomethyl)norbornane (NORB), adamantane-1,3-diamine (ADDA), octahydro-4,7-methanoinden-1(2),5(6)-dimethanamine, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4,4'-diamino-2,2'-dimethylbiphenyl (m-TBHG), O-tolidine, 4,4'-methylenedianiline (4,4'-DAPM), 3,4'-methylenedianiline (3,4'-DAPM), 4,4'-diamino-3,3'-dimethyldiphenylmethane (MDA), 4,4'-methylenebis(2-ethylbenzeneamine) (MOEA), 4,4'-methylenebis(2,6-diethylaniline) (MDEA), 9,10-bis(4-aminophenyl)anthracene (ADA), 2,6-naphthalenediamine, 2,6-anthracenediamine, 4,4''-diamino-p-terphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane (AAF), α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene (bisaniline P), 9,9-bis(4-aminophenyl)fluorene (FDA), 3,3',5,5'-tetramethylbenzidine (TMB), 4,4'-diamino-2,2'-dimethoxybiphenyl (m-DS), 4,4'-diaminobenzophenone (DABP), or a combination thereof.

[0040] According to the embodiments of the present disclosure, when the reactant (a) consists of a first diamine and a second diamine, the weight ratio of the first diamine to the second diamine may be from 99.99:0.01 to 30:70, for example, 99:1, 95:5, 90:10, 80:70, 60:40, 50:50 or 40:60. According to the embodiments of the present disclosure, when the reactant (b) consists of a first dianhydride and a second dianhydride, the weight ratio of the first dianhydride to the second dianhydride may be from 99.99:0.01 to 25:75, for example, 99:1, 95:5, 90:10, 80:70, 60:40, 50:50, 40:60 or 30:70.

[0041] According to the embodiments of the present disclosure, the weight average molecular weight (Mw) of the polyimide of the present disclosure is from about 5,000 g / mol to 3,000,000 g / mol, for example, from about 8,000 g / mol to 2,500,000 g / mol, from 10,000 g / mol to 2,300,000 g / mol, from 15,000 g / mol to 2,000,000 g / mol, from 10,000 g / mol to 1,000,000 g / mol, from 10,000 g / mol to 500,000 g / mol or from 10,000 g / mol to 300,000 g / mol. The weight average molecular weight (Mw) of the polyimide of the present disclosure can be measured by gel permeation chromatography (GPC) based on the calibration curve of polystyrene.

[0042] According to the embodiments of the present disclosure, the above-mentioned adhesive may contain the above-mentioned polyimide and solvent, whereby the polyimide can be uniformly dispersed in the solvent. In addition, according to some embodiments of the present disclosure, the adhesive of the present disclosure may consist of the above-mentioned polyimide and solvent.

[0043] In an embodiment of the present disclosure, the solid content of the adhesive may be from 2 wt% to 25 wt% (for example, about 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, or 24 wt%). Here, the solid content refers to the weight percentage of the components of the adhesive excluding the solvent with respect to the total weight of the adhesive. According to an embodiment of the present disclosure, the thickness of the adhesive layer made from the adhesive is proportional to the solid content of the adhesive. That is, the thickness of the adhesive layer made from the adhesive can be adjusted by changing the solid content of the adhesive.

[0044] According to an embodiment of the present disclosure, the solvent may be benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, triethylbenzene, cyclohexane, cyclohexene, decahydronaphthalene, dipentene, pentane, hexane, heptane, octane, nonane, decane, ethylcyclohexane, methylcyclohexane, p-menthane, dipropyl ether, dibutyl ether, anisole, butyl acetate, pentyl acetate, methyl isobutyl ketone (MEK), cyclohexylbenzene, cyclohexanone, cyclopentanone (CPN), triglyme, 1,3-dimethyl-2-imidazolidinone (DMI), N-methyl-2-pyrrolidone (NMP), methyl ethyl ketone (MEK), N,N-dimethylacetamide (DMAc), γ-butyrolactone (GBL), N,N-dimethylformamide (DMF), propylene glycol methyl ether acetate (PGMEA), dimethyl sulfoxide (DMSO), cresol, or a combination thereof.

[0045] According to an embodiment of the present disclosure, the above-described polyimide can be produced by the following steps. First, reactant (a) and reactant (b) are added to a reaction flask containing a solvent to obtain a mixture. The solid content of the mixture can be from about 10 wt% to 50 wt% (for example, about 11 wt%, 12 wt%, 14 wt%, 15 wt%, 18 wt%, 20 wt%, 21 wt%, 22 wt%, 25 wt%, 27 wt%, 29 wt%, 30 wt%, 32 wt%, 34 wt%, 35 wt%, 38 wt%, 40 wt%, 42 wt%, 44 wt%, 46 wt%, or 48 wt%). Reactant (a) and reactant (b) are as defined above. The solvent used to produce the polyimide is such that the resulting polyimide can be directly dissolved in the solvent without the need for exchange, and may be selected from the group consisting of N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), γ-butyrolactone (GBL), N,N-dimethylformamide (DMF), cresol, cyclopentanone (CPN), and cyclohexanone. According to an embodiment of the present disclosure, the molar ratio of reactant (a) to reactant (b) may be from about 1:1.05 to 1.05:1, for example, about 1:1. Further, a catalyst may optionally be added to the solution to accelerate the polymerization process to form the polyimide. The amount of the catalyst may be from 0.1 wt% to 10 wt% (for example, about 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 5 wt%, 7 wt%, or 9 wt%) based on the total weight of reactant (a) and reactant (b). Then, the mixture is reacted at 180°C to 250°C for 4 to 12 hours to obtain a solution containing the polyimide of the present disclosure (i.e., a polyimide solution). According to an embodiment of the present disclosure, the catalyst may be any catalyst suitable for use in the imidization reaction, for example, a tertiary amine.Examples of tertiary amines include triethylenediamine (DABCO), N,N-dimethylcyclohexylamine, 1,2-dimethylimidazole, trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, triethylenediamine, N-methylpyrrolidone, N-ethylpyrrolidone, N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, methylpyridine, dimethylpyridine, quinoline, or isoquinoline.

[0046] According to an embodiment of the present disclosure, the polyimide solution obtained from the reaction can be directly used as the adhesive of the present disclosure, or the obtained polyimide solution can be further diluted with a solvent and used as the adhesive of the present disclosure. The adhesive of the present disclosure consists essentially of the disclosed polyimide and solvent. Specifically, the polyimide and solvent are the main components of the adhesive, and the amounts of the polyimide and solvent may be from about 90 wt% to 99.99 wt% of the adhesive (for example, 93 wt%, 95 wt%, 98 wt%, 99 wt%, or 99.5 wt%). In addition, the adhesive contains trace components other than the polyimide and solvent. These trace components may include a catalyst used in the production of the polyimide, unreacted portions of reactant (a) and / or reactant (b), additives, or combinations thereof. The total weight of the trace components in the adhesive may be from about 0.01 wt% to 10 wt%. According to an embodiment of the present disclosure, the additive may be any additive known in the art, such as a filler, a flame retardant, a viscosity modifier, a thixotropic agent, an antifoaming agent, a leveling agent, a surface treatment agent, a stabilizer, an antioxidant, or combinations thereof. According to another embodiment of the present disclosure, the adhesive of the present disclosure may consist of the above-described main components and trace components. The viscosity of the adhesive of the present disclosure at 25°C may be from about 100 cP to 10,000 cP, for example, about 200 cP, 300 cP, 500 cP, 1,000 cP, 1,200 cP, 1,500 cP, or 1,800 cP. The viscosity of the adhesive of the present disclosure is measured using a viscometer (ViscoleadOne, manufactured by Fungilab).

[0047] Embodiments of the present disclosure provide a multilayer structure 10 shown in FIG. 1. The multilayer structure 10 includes a first substrate 20 and an adhesive layer 30 disposed on the first substrate 20. The adhesive layer 30 includes a cured product obtained by performing a baking process on the adhesive of the present disclosure. The thickness of the adhesive layer 30 is not particularly limited and can be selected according to actual needs. The average thickness of the adhesive layer 30 may be about 1 μm to 500 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 8 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 100 μm, 150 μm, 200 μm, 300 μm, or 400 μm. The first substrate 20 is not limited and can be arbitrarily changed by those skilled in the art. The first substrate 20 may include a metal plate, a silicon substrate, glass, or a polymer film, such as a polyethylene terephthalate (PET) film, a polybutylene terephthalate (PBT) film, a polyethylene (PE) film, a polyethylene naphthalate (PEN) film, a polypropylene (PP) film, a polyvinyl chloride (PVC) film, or a polyacrylate film.

[0048] According to an embodiment of the present disclosure, a multilayer structure 10 is formed by adhering a second substrate 40 to a first substrate 20 using an adhesive layer 30. According to an embodiment of the present disclosure, the first substrate 20 and the second substrate 40 can be two substrates that need to be bonded together. As shown in FIG. 2, the multilayer structure 10 further includes a second substrate 40, and the adhesive layer 30 is disposed between the first substrate 20 and the second substrate 40. Further, when the adhesive layer 30 of the multilayer structure 10 is irradiated with laser light (i.e., a laser separation process is performed), the adhesive strength of the adhesive layer 30 can be reduced (for example, the adhesive strength between the first substrate 20 and the second substrate 40 can be reduced to 40 gf or less). As a result, the second substrate 40 can be easily peeled off from the first substrate 20, and no adhesive residue remains on either the first substrate 20 or the second substrate 40. Therefore, the processing speed and the reuse rate of the electronic device are improved, and the efficiency of the processing and rework processes is increased. According to an embodiment of the present disclosure, the second substrate 40 can be an electronic device. In other words, the electronic device can be temporarily fixed to the first substrate 20 using the adhesive layer 30 of the present disclosure. In addition, the electronic device is not limited, and for example, a semiconductor chip, a touch panel, a display element, a diode, a solar cell, an organic light emitting diode (OLED), or other types of components can be included.

[0049] According to an embodiment of the present disclosure, the multilayer structure 10 can be fabricated by the following steps. First, a first substrate 20 is prepared. Next, an adhesive of the present disclosure is applied onto the first substrate 20 using a coating process. The coating process may be screen printing, spin coating, bar coating, blade coating, roller coating, dip coating, spray coating, or brush coating. Next, a baking process is performed on the coating to form the adhesive layer 30. The temperature of the baking process may be from about 50°C to 350°C, or 300°C or less (for example, from 150°C to 280°C), and the process time of the baking process may be from 30 minutes to 8 hours. In an embodiment, the baking process may be a single-stage or multi-stage process. For example, bake at 100°C to 200°C for 15 minutes to 2 hours, and then bake at 200°C to 350°C for 15 minutes to 6 hours. After forming the adhesive layer 30, a second substrate 40 can be disposed on the upper surface of the adhesive layer 30. Next, a pressing process is performed on the obtained product to obtain the multilayer structure 10. The temperature of the pressing process may be from about 50°C to 350°C, and the pressing time may be from 3 minutes to 8 hours.

[0050] Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily understand them. The inventive concept can be embodied in various forms without being limited to these exemplary embodiments shown herein. For clarity, descriptions of well-known parts are omitted, and like reference numerals throughout indicate like components.

[0051] Fabrication of Polyimide Table 1 lists the reagents related to the production examples of the present disclosure.

[0052]

Table 1-1

Table 1-2

[0053] Production Examples 1 to 9 According to the components and amounts shown in Table 2, Production Examples 1 to 9 were carried out by adding reactant (a), reactant (b), and isoquinoline to a reaction flask. Gamma-butyrolactone (GBL) was used as a solvent to prepare a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200 °C for 6 hours under a nitrogen atmosphere to produce polyimide solutions (1) to (9) with a solid content of about 29 wt%. The total weight percentage of the first diamine and the first dianhydride with respect to the total weight of reactant (a) and reactant (b) was calculated and shown in Table 2. After allowing the obtained polyimides (1) to (9) to stand for 30 minutes, it was observed that they were all homogeneous mixtures.

[0054] [Table 2]

[0055] Production Examples 10 to 15 According to the components and amounts shown in Table 3, Production Examples 10 to 15 were carried out by adding reactant (a), reactant (b), and isoquinoline to a reaction flask. Gamma-butyrolactone (GBL) was used as a solvent to prepare a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200 °C for 6 hours under a nitrogen atmosphere to produce polyimide products (10) to (15) with a solid content of about 29 wt%. The total weight percentage of the first diamine and the first dianhydride with respect to the total weight of reactant (a) and reactant (b) was calculated and shown in Table 3. After allowing the obtained polyimides (10) to (15) to stand for 30 minutes, it was observed that they had phase-separated.

[0056]

Table 3

[0057] Production Examples 16 to 23 According to the components and amounts shown in Table 4, Production Examples 16 to 23 were carried out by adding Reactant (a), Reactant (b), and isoquinoline to a reaction flask. Gamma-butyrolactone (GBL) was used as a solvent to make a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200 °C for 6 hours under a nitrogen atmosphere to produce polyimide products (16) to (23) with a solid content of about 29 wt%. The total weight percentage of the first diamine and the first dianhydride with respect to the total weight of Reactant (a) and Reactant (b) was calculated and shown in Table 4. After allowing the obtained polyimides (16) to (23) to stand for 30 minutes, it was observed that the obtained polyimide products (16) to (23) exhibited the following states. The polyimide product (16) showed phase separation, the polyimide products (17) and (19) became turbid mixtures, and the products containing polyimides (18) and (20) to (23) became homogeneous mixtures.

[0058]

Table 4

[0059] Production Examples 24 to 31 According to the components and amounts shown in Table 5, Production Examples 24 to 31 were carried out by adding Reactant (a), Reactant (b), and isoquinoline to a reaction flask. Gamma-butyrolactone (GBL) was used as a solvent to make a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200 °C for 6 hours under a nitrogen atmosphere to produce polyimide solutions (24) to (31) with a solid content of about 29 wt%. The total weight percentage of the first diamine and the first dianhydride with respect to the total weight of Reactant (a) and Reactant (b) was calculated and shown in Table 5. After allowing the obtained polyimides (24) to (31) to stand for 30 minutes, it was observed that all of them were homogeneous mixtures.

[0060]

Table 5

[0061] Preparation of Adhesive Examples 1 - 22 Solutions (34.48 parts by weight) of polyimides (1) - (9), (18), and (20) - (31) obtained from Preparation Examples 1 - 9, 18, and 20 - 31 were each mixed with γ - butyrolactone (165 parts by weight). After stirring for 30 minutes, adhesives (1) - (22) with a solid content of about 5 wt% were obtained.

[0062] The viscosities of adhesives (1) - (22) were measured at 25°C using a viscometer (Viscolead One, manufactured by Fungilab), and the results are shown in Table 6.

[0063]

Table 6

[0064] Preparation of Test Samples 4 - inch glass substrates (commercially available from William Optical Technology Corporation) were prepared. Then, adhesives (1) - (22) were spin - coated on one 4 - inch glass substrate at 1000 rpm for 60 seconds each to form thin films on the glass substrates. A drying process was performed on the thin films (baked at 200°C for 60 minutes and then baked at 280°C for 60 minutes). After the thin films cooled, samples (1) - (22) (having an adhesive layer / glass substrate structure) were obtained.

[0065] Next, the average thickness, glass transition temperature (Tg), and transmittance at 355 nm of the adhesive layers (1) to (22) were measured, and the results are shown in Table 7. The average thickness was measured with a white light interferometer (commercially available from Agewell Technology Corp). These were obtained by measuring the thicknesses at six points in the adhesive layer and then averaging those values. The glass transition temperature was analyzed by a differential scanning calorimeter (Discovery DSC25) under a nitrogen atmosphere with a heating rate of 10 °C / min from room temperature to the onset decomposition temperatures of the adhesive layer. The transmittance of the adhesive layer was measured at a wavelength of 355 nm with a UV / Vis / NIR spectrophotometer (LAMBDA 1050).

[0066]

Table 7

[0067] As shown in Tables 2 to 5 and 7, when polyimide is prepared using specific diamines and dianhydrides of the present disclosure and the total weight percentage of the first diamine and the first dianhydride is controlled within the range of 55 wt% to 94 wt%, the glass transition temperature (Tg) of the resulting adhesive layer is within the range of 180 °C to 245 °C, and the ultraviolet transmittance at 355 nm is 5% or less. Conversely, when the total weight percentage of the first diamine and the first dianhydride is lower than 55 wt% or higher than 94 wt%, the glass transition temperature (Tg) of the resulting adhesive layer is outside the range of 180 °C to 245 °C, or the ultraviolet transmittance at 355 nm is greater than 5%. In addition, when only cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) or only 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA) is used as the second dianhydride, the resulting reaction product is not a homogeneous mixture. Similarly, when only isophoronediamine (IPDA) or only 4-methylcyclohexane-1,3-diamine (HTDA) is used as the second diamine, the resulting reaction product is not a homogeneous mixture. These results indicate that the solubility of the obtained polyimide in GBL is lower.

[0068] Fabrication of Multilayer Structure A 4-inch wafer was prepared, and then samples (1) to (22) were respectively adhered to one 4-inch wafer. The electrodes of the 4-inch wafer were brought into contact with the adhesive layers of samples (1) to (22). A load of 5 kg was applied to the ends of the obtained 4-inch wafers with multilayer combinations, and then baked at 300 °C for 60 minutes. After cooling to RT, multilayer structures (1) to (22) were obtained. Next, an adhesion test was performed on the 4-inch wafers adhered to the glass substrates in multilayer structures (1) to (22). The adhesion test was assumed to include the following steps. Each of multilayer structures (1) to (22) was turned upside down with the 4-inch wafer facing downward and maintained as it was for 10 minutes. If the 4-inch wafer was peeled off from the glass substrate, the adhesion test of that multilayer structure was recorded as ×. If it was not peeled off, it was recorded as ○. The results are shown in Table 8.

[0069] Next, a peeling test was conducted to evaluate whether the 4-inch wafers in multilayer structures (1) to (22) were separated from the glass substrates after the laser separation process. The peeling test was assumed to include the following steps. Laser light with a wavelength of 355 nm (output 2 kW, scanning irradiation speed 3 m / s) from a laser device (commercially available from Kin-Yo Optoelectronics) was irradiated onto the adhesive layer of the multilayer structure. After irradiation, the adhesion strength between the glass substrate and the 4-inch wafer was measured using a tensile tester (QC-506B1, Guang Rhenium Instrument Co.) at a tensile force of 90 degrees (tensile speed upward of 300 mm / min). The results are shown in Table 8.

[0070] Next, the 4-inch wafers of multilayer structures (1) to (22) were inspected to evaluate the adhesive residue after peeling them from the glass substrates. The evaluation method was assumed to include the following steps. The 4-inch wafers of multilayer structures (1) to (22) were removed from the glass substrates, rinsed with isopropanol (IPA), and washed. Next, the 4-inch wafers were examined using an optical microscope to evaluate the adhesive residue. The results are shown in Table 8.

[0071]

Table 8

[0072] As shown in Table 8, when the glass transition temperature (Tg) of the obtained adhesive layer is in the range of 180°C to 245°C, the 4-inch wafer and the glass substrate are adhered via the adhesive layer in a thermal compression bonding process using a relatively low temperature. In addition, when the UV transmittance of the adhesive layer is low, it is easier to absorb laser light, which facilitates the peeling of the wafer from the glass substrate. Since the total amount of the first diamine and the first dianhydride used to form the polyimide in the multilayer structure (7) is less than 55 wt%, the glass transition temperature of the adhesive layer is higher, so it is difficult for the adhesive layer to soften during the thermal compression bonding process, and it is difficult for the wafer and the glass substrate to adhere. In the multilayer structure (8), since the absorption of the laser light with a wavelength of 355 nm by the adhesive layer is relatively weak, the wafer and the glass substrate do not separate (adhesion strength > 50 gf). In the multilayer structure (9), since the glass transition temperature of the adhesive layer is lower (<180°C), the adhesive layer is likely to be confined to the side wall of the electrode and is likely to form adhesive residue.

[0073] As described above, by controlling the total weight of the diamine containing a diphenyl ether moiety and the dianhydride containing a diphenyl ether moiety, as well as the total weight of the reactant (a) and the reactant (b) so as to satisfy a specific relationship, the glass transition temperature (Tg) of the polyimide of the present disclosure is in the range of 180°C to 245°C, and the UV transmittance of the polyimide at wavelengths from 260 nm to 355 nm is 5% or less. As a result, the first substrate and the second substrate can be adhered at a lower processing temperature by the adhesive containing the polyimide of the present disclosure, and warping of the substrate caused by high-temperature processing is avoided. In addition, since the UV light is absorbed by the adhesive containing the polyimide, the first substrate and the second substrate can be separated by irradiation with laser light. As a result, separation of the electronic element from the substrate during processing or rework becomes possible, and no adhesive residue is formed.

[0074] Although the present disclosure has been described by way of examples from the perspective of preferred embodiments, it should be understood that the present disclosure is not limited to those disclosed embodiments. Rather, it is intended to cover various modifications and similar configurations (which would be apparent to those skilled in the art). Therefore, the broadest interpretation should be given to the scope of the appended claims so as to include all such modifications and similar configurations.

Explanation of Reference Numerals

[0075] 10 ··· Multilayer structure 20 ··· First substrate 30 ··· Adhesive layer 40 ··· Second substrate

Claims

1. An adhesive comprising a polyimide, wherein the polyimide is a reaction product of a reactant (a) and a reactant (b), the reactant (a) is a first diamine or the reactant (a) consists of the first diamine and a second diamine, and the reactant (b) consists of a first dianhydride and a second dianhydride, the first diamine is a diamine containing a diphenyl ether moiety, the first dianhydride is a dianhydride containing a diphenyl ether moiety, the second diamine is not a diamine containing a diphenyl ether moiety, and the second dianhydride is not a dianhydride containing a diphenyl ether moiety, and based on the total weight of the reactant (a) and the reactant (b), the total weight percentage of the first diamine and the first dianhydride is from 55 wt% to 94 wt%, and the molar ratio of the reactant (a) to the reactant (b) is from 1:1.05 to 1.05:

1.

2. The adhesive according to claim 1, wherein the first dianhydride is at least one of dianhydrides having a structure represented by formula (I). 【Chemical 1】 (wherein R １ is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, a is independently 0, 1, 2 or 3, and A １ is -O- 【Chemical 2】 and R ２ is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, b is independently 0, 1, 2, 3 or 4, and R ３ is independently hydrogen, fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, and R ４ is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, and c is independently 0, 1, 2, 3, 4, 5 or 6.)

3. The adhesive according to claim 1, wherein the first diamine is at least one of diamines having a structure represented by formula (II). 【Chemical Formula 3】 (wherein, R ５ is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, d is independently 0, 1, 2, 3 or 4, and A ２ is -O-, 【Chemical Formula 4】 and R ６ is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, e is independently 0, 1, 2, 3 or 4, and R ７ is independently hydrogen, fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, and R ８ is independently fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group or a C1-C4 alkoxy group, and f is independently 0, 1, 2, 3, 4, 5 or 6.)

4. The adhesive according to claim 1, wherein the second dianhydride does not consist of cyclobutane-1,2,3,4-tetracarboxylic dianhydride or the second dianhydride does not consist of 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

5. The adhesive according to claim 1, wherein the second dianhydride is bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclooctane tetracarboxylic dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, [3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride], 1,2,3,4-butanetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 5-[4-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione, 5-[3-(1,3-dioxo-2-benzofuran-5-yl)phenyl]-2-benzofuran-1,3-dione, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, or a combination thereof.

6. The adhesive according to claim 1, wherein the second diamine does not consist of isophorone diamine, or the second diamine does not consist of 4-methylcyclohexane-1,3-diamine.

7. The adhesive according to claim 1, wherein the second diamine is 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), bis(aminomethyl)norbornane, adamantane-1,3-diamine, octahydro-4,7-methanoinden-1(2),5(6)-dimethanamine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-diamino-2,2'-dimethylbiphenyl, O-tolidine, 4,4'-methylenedianiline, 3,4'-methylenedianiline, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-methylenebis(2-ethylbenzeneamine), 4,4'-methylenebis(2,6-diethylaniline), 9,10-bis(4-aminophenyl)anthracene, 2,6-naphthalenediamine, 2,6-anthracenediamine, 4,4''-diamino-p-terphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, 9,9-bis(4-aminophenyl)fluorene, 3,3',5,5'-tetramethylbenzidine, 4,4'-diamino-2,2'-dimethoxybiphenyl, 4,4'-diaminobenzophenone, or a combination thereof.

8. The adhesive according to claim 1, wherein the weight average molecular weight of the polyimide is from 5,000 g / mol to 3,000,000 g / mol.

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