Adhesive and multilayer structure

Abstract

The invention provides an adhesive and a multilayer structure. The adhesive comprises 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) is composed of the first diamine and a second diamine, and the reactant (b) is composed of a first dianhydride and a second dianhydride, wherein the first diamine is a diamine having a diphenyl ether group, the first dianhydride is a dianhydride having a diphenyl ether group, the second diamine is a diamine not having a diphenyl ether group, and the second dianhydride is a dianhydride not having a diphenyl ether group, the sum of the weight percentages of the first diamine and the first dianhydride being 55 wt% to 94 wt%, and the sum of the weight percentages of the second diamine and the first dianhydride is 55 wt% to 94 wt%. The total weight of the reactant (a) and the reactant (b) is taken as the reference.

Description

Technical Field

[0001] The present disclosure relates to an adhesive and a multi-layer structure. Background Art

[0002] Advanced wafer processes are moving towards smaller and finer linewidth processes. To avoid problems such as wafer breakage or residual glue in wafer processes, it is necessary to improve the dimensional stability and heat resistance of the glue material used to temporarily protect the wafer.

[0003] Existing temporary wafer protection glue materials include acrylic bonding glue and polyamic acid bonding glue. The poor heat resistance of acrylic bonding glue (≤150 °C) is not conducive to semiconductor processes, and its soft nature makes it easy to get stuck in the sidewalls between electrodes to form residual glue. Polyamic acid bonding glue is prepared in a two-step process, which includes coating a polyamic acid material on a substrate and subjecting it to high-temperature treatment (process temperature above about 300 °C) to form a polyimide film by the dead circulation of polyamic acid. However, such a high process temperature easily causes stress due to the large difference in thermal expansion coefficients between the polyimide and the substrate, resulting in the substrate bending, deforming or cracking, and even delamination, thus damaging the components.

[0004] Therefore, the industry needs a novel glue material suitable for advanced wafer processes. Summary of the Invention

[0005] According to an embodiment of the present disclosure, the present disclosure provides an adhesive. The adhesive is a reaction product of reactant (a) and reactant (b), where reactant (a) is a first diamine, or reactant (a) consists of the first diamine and a second diamine, where reactant (b) consists of a first dianhydride and a second dianhydride, where the first diamine is a diamine having a diphenyl ether group, the first dianhydride is a dianhydride having a diphenyl ether group, the second diamine is a diamine not having a diphenyl ether group, and the second dianhydride is a dianhydride not having a diphenyl ether group, and the total weight percentage of the first diamine and the first dianhydride is 55 wt% (weight percent) to 94 wt%, based on the total weight of reactant (a) and reactant (b).

[0006] According to an embodiment of the present disclosure, the present disclosure further provides a multi-layer structure, including a first substrate, and an adhesive layer disposed on the first substrate, where the adhesive layer is a cured product of the adhesive described in the present disclosure. Brief Description of the Drawings

[0007] Figure 1 A schematic diagram showing the multi-layer structure according to an embodiment of the present disclosure.

[0008] Figure 2Schematic diagram showing a multi-layer structure according to other embodiments of the present disclosure. Detailed implementation mode

[0009] The following provides a detailed description of the adhesive and multi-layer structure according to the present disclosure. It should be understood that the following description provides many different embodiments or examples for implementing different aspects of the present disclosure. The specific components and arrangements described below are only for a simple description of the present disclosure. Of course, these are only for illustration and not a limitation of the present disclosure. In the present disclosure, the term "about" means that the specified quantity can be increased or decreased by an amount that those skilled in the art can recognize as normal and reasonable.

[0010] Furthermore, ordinal numbers such as "first", "second", "third", etc. used in the specification and claims are used to modify the components of the claims. They do not inherently imply or represent that the component has any previous ordinal number, nor do they represent the order of one component and another component, or the order in the manufacturing method. The use of these ordinal numbers is only to clearly distinguish a component with a certain name from another component with the same name.

[0011] It must be understood that the components specifically described or illustrated may exist in various forms well known to those of ordinary skill in the art. In addition, when a layer is "on" another layer or substrate, it may mean "directly" on the other layer or substrate, may mean a layer on the other layer or substrate, or may mean that a layer is sandwiched between the other layer or substrate. In the drawings, the shape or thickness of the embodiments may be enlarged for simplicity or convenience of labeling. Furthermore, each component in the drawings will be described separately. It should be noted that the components not shown or described in the drawings are in forms well known to those of ordinary skill in the art. In addition, specific embodiments are only used to disclose the specific ways of using the present disclosure, and they are not used to limit the present disclosure.

[0012] The present disclosure provides an adhesive and a multilayer structure, such as an adhesive that can be removed by laser and is not prone to residual adhesive, and a multilayer structure including an adhesive layer prepared from the adhesive. According to an embodiment of the present disclosure, the adhesive described in the present disclosure includes polyimide. The polyimide can be obtained by reacting a specific diamine (such as a diamine having a diphenyl ether group) as reactant (a) with a specific dianhydride (such as a dianhydride having a diphenyl ether group and a dianhydride not having a diphenyl ether group) as reactant (b). By controlling the total weight of the diamine having a diphenyl ether group and the dianhydride having a diphenyl ether group to be in a specific relationship with the total weight of reactant (a) and reactant (b), the polyimide described in the present disclosure can have a glass transition temperature (Tg) between 180 °C and 245 °C and low ultraviolet light transmittance (the transmittance of light with wavelengths in the range of 260 nm and 355 nm is less than or equal to 5%). In this way, the adhesive containing the polyimide can bond a first substrate (such as a transparent carrier) and a second substrate (such as an electronic component) at a lower process temperature (such as less than or equal to 300 °C), avoiding warping of the substrate due to stress generated by high-temperature processes. In addition, since the adhesive can absorb ultraviolet light (i.e., has low ultraviolet light transmittance), a laser can be used to irradiate and remove the adhesive layer prepared from the adhesive described in the present disclosure. In this way, the electronic component can be smoothly separated from the substrate during processing or rework processes without causing residue of the adhesive material. Furthermore, according to an embodiment of the present disclosure, the adhesive layer formed using the adhesive described in the present disclosure is a single-layer structure. Therefore, the adhesive described in the present disclosure only needs to be coated once, which can streamline the process and improve production capacity.

[0013] According to an embodiment of the present disclosure, the present disclosure provides an adhesive, wherein the adhesive includes polyimide. According to an embodiment of the present disclosure, the polyimide can be a reaction product of reactant (a) and reactant (b), wherein reactant (a) can be a first diamine, or reactant (a) can be composed of a first diamine and a second diamine. Reactant (b) is composed of the first dianhydride and the second dianhydride. According to an embodiment of the present disclosure, the first diamine can be a diamine having a diphenyl ether group (the structure can be

[0014] wherein the hydrogen on at least one carbon can be optionally substituted by fluorine, a C1-C4 alkyl group, a C1-C4 fluoroalkyl group, a C1-C4 fluoroalkoxy group, or a C1-C4 alkoxy group), and the first dianhydride can be a dianhydride having a diphenyl ether group (the structure can be The hydrogen on at least one carbon 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 is a diamine without a diphenyl ether group (i.e., the first diamine is different from the second diamine), and the second dianhydride is a dianhydride without a diphenyl ether group (i.e., the first dianhydride is different from the second dianhydride). It should be noted that the polyimide described in the present disclosure has a glass transition temperature (Tg) between 180°C and 245°C (e.g., 190°C, 200°C, 210°C, 220°C, 230°C, or 240°C) and low ultraviolet light transmittance (the transmittance of light with wavelengths in the range of 260 nm and 355 nm is less than or equal to 5%, e.g., 4%, 3%, 2%, or 1%). According to an embodiment of the present disclosure, the total weight percentage of the first diamine and the first dianhydride is 55 wt% to 94 wt% (e.g., 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%) based on the total weight of the reactants (a) and the reactants (b). When the weights of the first diamine and the first dianhydride are controlled within the above ranges, the polyimide described in the present disclosure can have a glass transition temperature (Tg) between 180°C and 245°C and low ultraviolet light transmittance (the transmittance of light with wavelengths in the range of 260 nm and 355 nm is less than or equal to 5%).

[0015] According to an embodiment of the present disclosure, when the reactant (a) is the first diamine and the reactant (b) consists of the first dianhydride and the second dianhydride, the total percentage by weight of the second dianhydride can be 6 wt% to 45 wt% based on the total weight of the reactants (a) and the reactants (b) (i.e., all the dianhydrides and diacids used to prepare the polyimide). According to an embodiment of the present disclosure, when the reactant (a) consists of the first diamine and the second diamine and the reactant (b) consists of the first dianhydride and the second dianhydride, the total weight percentage of the second diamine and the second dianhydride can be 6 wt% to 45 wt% based on the total weight of the reactants (a) and the reactants (b).

[0016] According to an embodiment of the present disclosure, the first dianhydride can be at least one dianhydride having the structure shown in formula (I)

[0017]

[0018] , 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; A 1 is -O- 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; R3 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; R4 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.

[0019] According to an embodiment of the present disclosure, the first dianhydride may be

[0020]

[0021]

[0022]

[0023] or a combination thereof, 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; 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 diamine having the structure shown in formula (II)

[0025]

[0026] , 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; A 2 is -O- 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; 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; and f is independently 0, 1, 2, 3, 4, 5, or 6.

[0027] According to an embodiment of the present disclosure, the first diamine may be

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] or a combination thereof, 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; 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; 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 8independently 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.

[0036] According to an embodiment of the present disclosure, the alkyl group described in the present disclosure may be a linear or branched alkyl group. According to an embodiment of the present disclosure, the C1-C4 alkyl group may be methyl, ethyl, propyl, butyl, or an isomer thereof. For example, the C1-C4 alkyl group described in the present disclosure may be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, iso-butyl, or tert-butyl.

[0037] According to an embodiment of the present disclosure, the C1-C4 alkoxy group described in the present disclosure may be a linear or branched alkoxy group. For example, the C1-C4 alkoxy group may be methoxy, ethoxy, propoxy, butoxy, or an isomer thereof.

[0038] According to an embodiment of the present disclosure, a C1-C4 fluoroalkyl group refers to an alkyl group in which all or part of the hydrogen on the carbon is replaced by fluorine, and may be linear or branched, such as fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, or an isomer thereof. Herein, the fluoromethyl group described in the present disclosure may be monofluoromethyl, difluoromethyl, or perfluoromethyl, and the fluoroethyl group may be monofluoroethyl, difluoroethyl, trifluoroethyl, tetrafluoroethyl, or perfluoroethyl.

[0039] According to an embodiment of the present disclosure, the C1-C4 fluoroalkoxy group described in the present disclosure may be a linear or branched fluoroalkoxy group. For example, the C1-C4 fluoroalkoxy group may be fluoromethoxy, fluoroethoxy, fluoropropoxy, fluorobutoxy, or an isomer thereof. Herein, the fluoromethoxy group described in the present disclosure may be monofluoromethoxy, difluoromethoxy, or perfluoromethoxy, and the fluoroethoxy group may be monofluoroethoxy, difluoroethoxy, trifluoroethoxy, tetrafluoroethoxy, or perfluoroethoxy.

[0040] According to an embodiment of the present disclosure, the second dianhydride described in the present disclosure is different from the first dianhydride, wherein the second dianhydride may be a dianhydride without a diphenyl ether group. According to an embodiment of the present disclosure, the second dianhydride is not composed of cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), or the second dianhydride is not composed of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA).

[0041] 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 may be bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride2) 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′-biphenyl tetracarboylic 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.

[0042] 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 further includes bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride2) 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 ([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′-biphenyl tetracarboylic 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 (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 (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.

[0043] According to an embodiment of the present disclosure, the second diamine is different from the first diamine, wherein the second diamine may be a diamine without a diphenyl ether group. According to an embodiment of the present disclosure, the second diamine does not consist of isophorone diamine (IPDA), or the second diamine does not consist of 1-methyl-2,4-cyclohexanediamine (HTDA).

[0044] 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 may be 4,4′-methylenebis(cyclohexylamine) (PACM), 4,4′-methylenebis(2-methylcyclohexylamine) (MACM), bis(aminomethyl)norbornane (NORB), adamantane-1,3-diamine (ADDA), octahydro-4,7-methanoindene-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-ethylbenzenamine) (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, 2,2-bis(4-aminophenyl)hexafluoropropane, AAF), α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene (BisanilineP), 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.,

[0045] According to an embodiment of the present disclosure, when the second diamine does not consist of isophoronediamine (IPDA) or does not consist of 4-methylcyclohexane-1,3-diamine (HTDA), the second diamine includes 4,4′-methylenebis(cyclohexylamine) (PACM), 4,4′-methylenebis(2-methylcyclohexylamine) (MACM), bis(aminomethyl)norbornane (NORB), adamantane-1,3-diamine (ADDA), octahydro-4,7-methanoindene-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-ethylbenzenamine) (MOEA), 4,4′-methylenebis(2,6-diethylaniline) (MDEA), 9,10-bis(4-aminophenyl)anthracene (ADA), 2,6-naphthalenediamine, 2,6-anthracenediamine, 4,4″-diaminotriphenyl, 4,4″-diamino-p-terphenyl), 2,2-bis(4-aminophenyl)hexafluoropropane (AAF), α,α′-bis(4-aminophenyl)-1,4-diisopropylbenzene (BisanilineP), 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.

[0046] According to an embodiment of the present disclosure, when the reactant (a) is composed of the first diamine and the second diamine, the weight ratio of the first diamine to the second diamine can be from 99.99:0.01 to 30:70, such as 99:1, 95:5, 90:10, 80:70, 60:40, 50:50, or 40:60. According to an embodiment of the present disclosure, when the reactant (b) is composed of the first dianhydride and the second dianhydride, the weight ratio of the first dianhydride to the second dianhydride can be from 99.99:0.01 to 25:75, such as 99:1, 95:5, 90:10, 80:70, 60:40, 50:50, 40:60, or 30:70.

[0047] According to an embodiment of the present disclosure, the weight average molecular weight (Mw) of the polyimide described in the present disclosure can be from about 5,000 g / mol to 3,000,000 g / mol, such as from about 8,000 g / mol to 2,500,000 g / mol, 10,000 g / mol to 2,300,000 g / mol, 15,000 g / mol to 2,000,000 g / mol, 10,000 g / mol to 1,000,000 g / mol, 10,000 g / mol to 500,000 g / mol, or 10,000 g / mol to 300,000 g / mol. The weight average molecular weight (Mw) of the polyimide described in the present disclosure can be measured by gel permeation chromatography (GPC) (using polystyrene as a standard to prepare a calibration curve).

[0048] According to an embodiment of the present disclosure, the adhesive described in the present disclosure may include the polyimide and the solvent described in the present disclosure, such that the polyimide is uniformly dispersed in the solvent. Additionally, according to certain embodiments of the present disclosure, the adhesive described in the present disclosure may consist of the polyimide and the solvent described in the present disclosure.

[0049] According to an embodiment of the present disclosure, the solid content of the adhesive may be from 2 wt% to 25 wt% (such as about 3 wt%, 4 wt%, 5 wt%, 3 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%). Herein, the solid content refers to the weight percentage of all components other than the solvent, based on the total weight of the adhesive. According to an embodiment of the present disclosure, the thickness of the adhesive layer prepared from the adhesive is proportional to the solid content of the adhesive. In other words, the thickness of the adhesive layer prepared from the adhesive can be adjusted by the solid content of the adhesive.

[0050] 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, methyl cyclohexane, p-menthane, dipropyl ether, dibutyl ether, anisole, butylacetate, pentyl acetate, methyl isobutyl ketone, 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 glycolmethyl ether acetate (PGMEA), dimethyl sulfoxide (DMSO), cresol, or a combination thereof.

[0051] According to an embodiment of the present disclosure, the polyimide described in the present disclosure can be prepared by the following steps. First, reactant (a) and reactant (b) are added to a reaction flask, and a solvent is added to obtain a mixture. The solid content of this mixture can be about 10 wt% to 50 wt% (such as 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%). The definitions of reactant (a) and reactant (b) are as described above. According to an embodiment of the present disclosure, in order to make the polyimide obtained subsequently directly soluble in the solvent used without the need to replace it with other solvents, the solvent used to prepare the polyimide can 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) can be about 1:1.05 to 1.05:1, such as about 1:1. According to an embodiment of the present disclosure, to accelerate the polymerization reaction to form polyimide, a catalyst can be added to the solution as needed, wherein the dosage of the catalyst can be 0.1 wt% to 10 wt% (such as about 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 5 wt%, 7 wt%, 9 wt%), based on the total weight of reactant (a) and reactant (b). Then, after reacting the mixture at 180°C to 250°C for 4 to 12 hours, a solution containing the polyimide described in the present disclosure (polyimide solution) is obtained. According to an embodiment of the present disclosure, the above catalyst can be any catalyst that can be used in the imidization reaction, such as a tertiary amine (tertiary amine).For example, the tertiary amine may include triethylenediamine (DABCO), N,N-dimethylcyclohexylamine, 1,2-dimethylimidazole, trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine, N-methylhexahydropyridine, N-ethylhexahydropyridine, imidazole, pyridine, picoline, lutidine, quinoline or isoquinoline.

[0052] According to an embodiment of the present disclosure, the obtained polyimide solution can be directly used as the adhesive described in the present disclosure, or the obtained polyimide solution can be further diluted with a solvent and then used as the adhesive described in the present disclosure. According to an embodiment of the present disclosure, the adhesive described in the present disclosure is substantially composed of the polyimide and the solvent described in the present disclosure. In other words, the polyimide and the solvent are the main components of the adhesive, and the total weight of the polyimide and the solvent accounts for 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 components other than the polyimide and the solvent in the adhesive are defined as minor components. According to an embodiment of the present disclosure, the minor component may be a catalyst used to prepare the polyimide, unreacted reactant (a) and / or reactant (b) used to prepare the polyimide, an additive, or a combination thereof. The total weight of the minor components accounts for about 0.01 wt% to 10 wt% of the adhesive. According to an embodiment of the present disclosure, the additive may be a conventionally known additive 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 a combination thereof. According to other embodiments of the present disclosure, the adhesive described in the present disclosure may be composed of the above-mentioned main components and minor components. According to an embodiment of the present disclosure, the viscosity of the adhesive described in the present disclosure at 25 °C may be about 100 cP to 10,000 cP, such as 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 described in the present disclosure is measured using a viscometer (Viscolead One, manufactured by Fungilab).

[0053] According to an embodiment of the present disclosure, the present disclosure provides a multilayer structure 10, such as Figure 1As shown. The multi-layer structure 10 may include a first substrate 20 and an adhesive layer 30 disposed on the first substrate 20, wherein the adhesive layer 30 is a cured product obtained by baking the adhesive described in the present disclosure. According to an embodiment of the present disclosure, the thickness of the adhesive layer 30 described in the present disclosure is not particularly limited and can be selected according to actual needs. According to an embodiment of the present disclosure, 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. According to an embodiment of the present disclosure, the first substrate 20 is not particularly limited and may be a metal sheet, 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).

[0054] According to an embodiment of the present disclosure, the adhesive layer 30 is used to fix the second substrate 40 on the first substrate 20 to obtain the multi-layer structure 10. According to an embodiment of the present disclosure, the first substrate 20 and the second substrate 40 may be two substrates that need to be joined. As Figure 2As shown, the multi-layer structure 10 further includes a second substrate 40, wherein the adhesive layer 30 is disposed between the first substrate 20 and the second substrate 40. In addition, after irradiating the adhesive layer 30 of the multi-layer structure 10 with a laser (i.e., performing a laser separation process on the multi-layer structure 10), the bonding ability of the adhesive layer 30 can be reduced (for example, the adhesion between the first substrate 20 and the second substrate 40 can be reduced to less than 40 gf). In this way, the second substrate 40 can be easily peeled off from the first substrate 20, and there will be no adhesive residue on the first substrate 20 and / or the second substrate 40, improving the process rate or process reuse rate of the electronic component and the efficiency of the processing or rework process. According to an embodiment of the present disclosure, the second substrate 40 can be an electronic component. In other words, the electronic component can be temporarily fixed to the first substrate 20 by using the adhesive layer 30 described in the present disclosure. According to an embodiment of the present disclosure, the electronic component is not particularly limited and can be, for example, a semiconductor chip, a touch panel, a display component, a diode, a solar component, or an organic light-emitting diode, etc.

[0055] According to an embodiment of the present disclosure, the multi-layer structure 10 can be prepared by the following steps. First, provide the first substrate 20. Then, form a coating on the first substrate 20 with the adhesive described in the present disclosure by a coating process. According to an embodiment of the present disclosure, the coating process can be screen printing, spin coating, bar coating, scraper coating, roller coating, dip coating, spray coating, or brush coating. Then, perform a baking process on the coating to form the adhesive layer 30. The temperature of the baking process can be about 50°C to 350°C, or not exceeding 300°C (for example: 150°C to 280°C), and the time of the baking process can be 30 minutes to 8 hours. According to an embodiment of the present disclosure, the baking process can be a one-stage or multi-stage baking process, and can be, for example, baking at 100°C to 200°C for 15 minutes to 2 hours, and baking at 200°C to 350°C for 15 minutes to 6 hours. After forming the adhesive layer 30, the second substrate 40 can be further disposed on the adhesive layer 30 and a pressing process is performed to obtain the multi-layer structure 10. According to an embodiment of the present disclosure, the temperature of the pressing process can be about 50°C to 350°C, and the time of the pressing process can be 3 minutes to 8 hours.

[0056] To make the above content, other purposes, features, and advantages of the present disclosure more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows.

[0057] Example

[0058] Preparation of Polyimide

[0059] Table 1 lists the reagents involved in the preparation examples of the present disclosure:

[0060] Table 1

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068] Preparation Examples 1 - 9

[0069] In Preparation Examples 1 - 9, the reactants (a), reactants (b), and isoquinoline were added to a reaction flask according to the components and contents shown in Table 2, and gamma-butyrolactone (GBL) was used as the solvent to obtain a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200°C for 6 hours under nitrogen to obtain solutions with polyimides (1) - (9) respectively (solid content of about 29 wt%). The total weight percentage of the first diamine and the first dianhydride was calculated (based on the total weight of the reactants (a) and the reactants (b)), and the results are shown in Table 2. Then, after standing for 30 minutes, the obtained solutions with polyimides (1) - (9) were observed, and it was found that these solutions were all homogeneous mixtures.

[0070] Table 2

[0071]

[0072]

[0073] Preparation Examples 10 - 15

[0074] Production Example 10-15: Reactants (a), (b), and isoquinoline were added to a reaction flask according to the components and contents shown in Table 3 respectively, and γ-butyrolactone (GBL) was used as the solvent to obtain a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200 °C for 6 hours under nitrogen to obtain products with polyimides (10)-(15) respectively (solid content about 29 wt%). The total weight percentage of the first diamine and the first dianhydride was calculated (based on the total weight of reactants (a) and (b)), and the results are shown in Table 3. Then, after standing for 30 minutes, the obtained products with polyimides (10)-(15) were observed, and it was found that phase separation occurred in these products.

[0075] Table 3

[0076]

[0077]

[0078] Production Example 16-23

[0079] Production Example 16-23: Reactants (a), (b), and isoquinoline were added to a reaction flask according to the components and contents shown in Table 4 respectively, and γ-butyrolactone (GBL) was used as the solvent to obtain a mixture with a solid content of about 30 wt%. Then, the mixture was reacted at 200 °C for 6 hours under nitrogen to obtain products with polyimides (16)-(23) respectively (solid content about 29 wt%). The total weight percentage of the first diamine and the first dianhydride was calculated (based on the total weight of reactants (a) and (b)), and the results are shown in Table 4. Then, after standing for 30 minutes, the obtained products with polyimides (16)-(23) were observed, and it was found that the product with polyimide (16) underwent phase separation, the products with polyimides (17) and (19) were turbid mixtures, and the products with polyimides (18) and (20)-(23) were phase-homogeneous mixtures.

[0080] Table 4

[0081]

[0082]

[0083] Production Example 24-31

[0084] Production Example 24 - 31 Reactants (a), reactants (b), and isoquinoline were added to a reaction flask according to the components and contents shown in Table 5 respectively, and γ-butyrolactone was used as the solvent to obtain a mixture with a solid content of about 30 wt%. Then, under nitrogen, the mixture was reacted at 200 °C for 6 hours to obtain solutions (with a solid content of about 29 wt%) having polyimides (24) - (31) respectively. The total weight percentage of the first diamine and the first dianhydride (based on the total weight of the reactants (a) and the reactants (b)) was calculated, and the results are shown in Table 5. Then, after standing for 30 minutes, the obtained solutions having polyimides (24) - (31) were observed, and it was found that these solutions were all homogeneous mixtures.

[0085] Table 5

[0086]

[0087]

[0088] Preparation of Adhesive

[0089] Examples 1 - 22

[0090] Solutions having polyimides (1) - (9), (18), and (20) - (31) (34.48 parts by weight) obtained from Production Examples 1 - 9, 18, and 20 - 31 were respectively 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.

[0091] At 25 °C, the adhesives (1) - (22) were measured using a viscometer (Viscolead One, manufactured by Fungilab)

[0092] and the results are shown in Table 6.

[0093] Table 6

[0094] Adhesive (1) Adhesive (2) Adhesive (3) Adhesive (4) Adhesive (5) Viscosity (cP) 965 976 994 1,007 983 Adhesive (6) Adhesive (7) Adhesive (8) Adhesive (9) Adhesive (10) Viscosity (cP) 892 926 941 935 938 Adhesive (11) Adhesive (12) Adhesive (13) Adhesive (14) Adhesive (15) Viscosity (cP) 917 972 884 928 973 Adhesive (16) Adhesive (17) Adhesive (18) Adhesive (18) Adhesive (20) Viscosity (cP) 892 963 938 895 947 Adhesive (21) Adhesive (22) Viscosity (cP) 951 927

[0095] Preparation of Adhesive Layer Specimens

[0096] 4-inch glass substrates (purchased from Weiyan Optics) were provided. Then, the adhesives (1) - (22) were respectively spin-coated (at a rotation speed of 1,000 rpm) onto the 4-inch glass substrates for 60 seconds to obtain films formed on the glass substrates. Then, a drying process (baking at 200 °C for 60 minutes and baking at 280 °C for 60 minutes) was performed on the films. After cooling, specimens (1) - (22) with the structure of adhesive layer / glass substrate were respectively obtained.

[0097] Next, the average thickness, glass transition temperature (Tg), and transmittance at 355 nm of the adhesive layers (1)-(22) of the test pieces (1)-(22) were measured. The results are shown in Table 7. The method for measuring the average thickness is as follows: The thicknesses of 6 points of the adhesive layer were measured using a white light interferometer (purchased from Anjiwei), and the average value of the 6 points was taken as the average thickness of the adhesive layer. The method for measuring the glass transition temperature is as follows: Analysis was carried out using a differential scanning calorimeter (DISCOVERY DSC25). The analysis conditions were heating from room temperature to the initial cracking temperature of the adhesive layer in a nitrogen atmosphere at a heating rate of 10 °C / minute. The method for measuring the transmittance is as follows: The transmittance of the adhesive layer was evaluated using an ultraviolet-visible-near-infrared spectrophotometer (UV / Vis / NIR Spectrophotometer, LAMBDA1050) with ultraviolet light of a wavelength of 355 nm.

[0098] Table 7

[0099]

[0100]

[0101] As can be seen from Tables 2-5 and 7, when polyimide is prepared using the specific diamines and dianhydrides described in the present disclosure, and the total weight percentage of the first diamine and the first dianhydride is in the range of 55 wt% to 94 wt%, the glass transition temperature (Tg) of the resulting adhesive layer can be in the range of 180 °C to 245 °C, and the ultraviolet transmittance at 355 nm can be less than or equal to 5%. On the contrary, when the total weight percentage of the first diamine and the first dianhydride is less than 55 wt% or higher than 94 wt%, the glass transition temperature (Tg) of the resulting adhesive layer cannot be in the range of 180 °C to 245 °C, or the ultraviolet transmittance at 355 nm is greater than 5%. In addition, when cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) or 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA) is used alone as the second dianhydride, or only isophorone diamine (IPDA) or 4-methylcyclohexane-1,3-diamine (HTDA) is used alone as the second diamine, the resulting solution is not a homogeneous mixture, and the resulting polyimide shown in the table has poor solubility in organic solvents.

[0102] Preparation of Multilayer Structure

[0103] Provide a 4-inch wafer. Then, respectively bond wafers (1)-(22) to the 4-inch wafer, where the wafer contacts the adhesive layer with its electrode. Then, apply a pressure of 5 kg to the wafer and bake it at 300 °C for 60 minutes. After cooling, multilayer structures (1)-(22) are obtained. Then, evaluate the bonding effect of the wafer on the glass carrier in multilayer structures (1)-(22). The evaluation method is as follows: Invert the multilayer structure and maintain it for 10 minutes. If the wafer falls off the glass carrier, the bonding effect is recorded as X; otherwise, it is recorded as O. The results are shown in Table 8.

[0104] Then, evaluate whether the wafer in multilayer structures (1)-(22) can be separated from the glass carrier after the laser separation process. The evaluation method is as follows: Use a laser machine (purchased from Qinyou Optoelectronics) to irradiate the adhesive layer of the multilayer structure with a laser of wavelength 355 nm (power 2 kw, scanning irradiation rate 3 m / s). After the scanning irradiation is completed, take out the multilayer structure, and then use a tensile testing machine (QC-506B1, Guanglai Instrument Company) to measure the adhesion force between the glass carrier and the wafer with a 90° tensile force (the upward pulling speed is 300 mm / min). The results are shown in Table 8.

[0105] Then, evaluate whether there is residual glue on the glass carrier after the wafer in multilayer structures (1)-(22) is debonded. The evaluation method is as follows: After the wafer is removed from the glass carrier, wet and clean the wafer with isopropanol (IPA). Then, observe with an optical microscope whether there is glue residue on the wafer. The results are shown in Table 8.

[0106] Table 8

[0107]

[0108]

[0109] As can be seen from Table 8, when the glass transition temperature (Tg) of the obtained adhesive layer is in the range of 180°C to 245°C, the wafer can be thermocompression bonded at a relatively low temperature. In addition, when the obtained adhesive layer has a low ultraviolet light transmittance, the adhesive layer is prone to absorb the laser of this wavelength, so the bonding between the wafer and the glass carrier plate can be released. In the multilayer structure (7), the amounts of the first diamine and the first dianhydride used to form the polyimide main chain are less than 55 wt%, resulting in a relatively high glass transition temperature of the adhesive layer, and it is not easy to soften and bond the wafer during the lamination process. In the multilayer structure (8), since the adhesive layer has a weak absorption of the 355-nm laser, the bonding between the wafer and the glass carrier plate cannot be released (adhesive force > 50 gf). In the multilayer structure (9), since the glass transition temperature of the adhesive layer is lower than 180°C, the adhesive layer is prone to get into the side walls between the electrodes to form residual glue.

[0110] In summary, by controlling the total weight of the dianhydride having a diphenyl ether group and the diamine having a diphenyl ether group to conform to a specific relationship with the total weight of the reactants (a) and the reactants (b), the polyimide described in the present disclosure has a glass transition temperature (Tg) between 180°C and 245°C and a low ultraviolet light transmittance (the transmittance of light with wavelengths in the range of 260 nm and 355 nm is less than or equal to 5%). In this way, the adhesive containing the polyimide can bond the first substrate and the second substrate at a relatively low process temperature, avoiding warping of the substrate caused by the stress generated by the high-temperature process. In addition, since the adhesive can absorb ultraviolet light, a laser can be used to irradiate and remove the adhesive layer prepared from the adhesive described in the present disclosure. In this way, during the processing or rework process, the electronic component can be smoothly separated from the substrate without causing residue of the adhesive material.

[0111] Although the present disclosure has been disclosed above with several embodiments, it is not intended to limit the present disclosure. Any person with ordinary knowledge in the technical field of the present disclosure can make any changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to that defined by the appended claims.

[0112] List of Reference Numerals

[0113] 10 Multilayer structure;

[0114] 20 First substrate;

[0115] 30 Adhesive layer; and

[0116] 40 Second substrate.

Claims

1. An adhesive comprising polyimide, wherein the polyimide is a reaction product of a reactant (a) and a reactant (b), wherein the reactant (a) is a first diamine or consists of the first diamine and a second diamine, and the reactant (b) consists of a first dianhydride and a second dianhydride, wherein the first diamine is a diamine having a diphenyl ether group, the first dianhydride is a dianhydride having a diphenyl ether group, the second diamine is a diamine without a diphenyl ether group, and the second dianhydride is a dianhydride without a diphenyl ether group, wherein the weight percentage of the first diamine and the first dianhydride is 55 wt % to 94 wt %, based on the total weight of the reactant (a) and the reactant (b).

2. The adhesive as claimed in claim 1, wherein the first dianhydride is at least one dianhydride having a structure shown in formula (I): Where R 1 independently fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; a independently represents 0, 1, 2, or 3; A 1 For -O-, R 2 independently fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; b independently represents 0, 1, 2, 3, or 4; R 3 R is independently hydrogen, fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; 4 independently fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; and, c independently is 0, 1, 2, 3, 4, 5, or 6.

3. The adhesive as claimed in claim 1, wherein the first diamine is at least one diamine having a structure represented by formula (II): Where R 5 independently fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; d independently represents 0, 1, 2, 3, or 4; A 2 For -O-, R 6 independently fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; e independently represents 0, 1, 2, 3, or 4; R 7 R is independently hydrogen, fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; 8 independently fluorine, C1-C4 alkyl, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, or C1-C4 alkoxy; and, f independently is 0, 1, 2, 3, 4, 5, or 6.

4. The adhesive as claimed in claim 1, wherein the second dianhydride is not composed of cyclobutane-1,2,3,4-tetracarboxylic dianhydride, or the second dianhydride is not composed of 1,2,4,5-cyclohexanetetracarboxylic dianhydride.

5. The adhesive as claimed in claim 1, wherein the second dianhydride is bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, bicyclooctane tetracarboxylic dianhydride, bicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic 1,4:2,3-dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, Benzenetetracarboxylic 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 dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, or a combination thereof. 6 . The adhesive as claimed in claim 1 , wherein the second diamine is not composed of isophorone diamine, or the second diamine is not composed of 1-methyl-2,4-cyclohexanediamine.

7. The adhesive as claimed in claim 1, wherein the second diamine is 4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis(2-methylcyclohexylamine), bicyclo[2.2.1]heptanedimethylamine, 1,3-adamantanediamine, bis(aminomethyl)tricyclo[5.2.1.02,6]decane, 2,2'-bis(trifluoromethyl)diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, o-dimethyl-p-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethylbiphenyl methane, 4,4'-methylenebis(2-ethyl)aniline, 4,4'-methylenebis(2,6-diethylaniline), 9,10-bis(4-aminophenyl)anthracene, 2,6-naphthalenediamine, 2,6-diaminoanthracene, 4,4"-diaminoterphenyl, 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 as claimed in claim 1 , wherein the molar ratio of reactant (a) to reactant (b) is 1:1.05 to 1.05:

1. 9 . The adhesive as claimed in claim 1 , wherein the weight average molecular weight of the polyimide is 5,000 g / mol to 3,000,000 g / mol.

10. The adhesive according to claim 1, further comprising: The solvent, wherein the solid content of the adhesive is 2wt% to 20wt%.

11. A multilayer structure comprising: a first substrate; and An adhesive layer disposed on the first substrate, wherein the adhesive layer is a cured product of the adhesive according to any one of claims 1 to 10. The multi-layer structure as claimed in claim 11 , wherein the first substrate is a transparent substrate.

13. The multilayer structure of claim 11, further comprising: The electronic component comprises the adhesive layer disposed between the first substrate and the electronic component.

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