Organosiloxane monomer, organosiloxane sealant and preparation method therefor, thin-film encapsulating method, and flexible semiconductor device

Abstract

Disclosed are an organosiloxane monomer, an organosiloxane sealant and a preparation method therefor, a thin-film encapsulating method, and a flexible semiconductor device. The organosiloxane monomer has a special chemical structure and is used in the organosiloxane sealant, and comprises the following components in parts by weight: 5-70 parts of an organosiloxane monomer, 15-80 parts of a reactive diluent, and 0.1-10 parts of a photoinitiator. The organosiloxane sealant is prepared by using the organosiloxane monomer with a specific structure as a main component of a semiconductor device encapsulating material in combination with other components. The sealant has low volume shrinkage, and also has low water vapor permeability and high light transmittance, has a strong adhesive force to a silicon nitride substrate, and can be effectively used for encapsulating a flexible semiconductor device.

Description

Organosiloxane monomer, organosiloxane sealant, preparation method thereof, thin film encapsulation method, and flexible semiconductor device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to a Chinese patent application filed with the Patent Office of China on July 17, 2023, with application number 202310877065.3 and application name “Organosiloxane monomer, organosiloxane sealant and preparation method thereof, thin film encapsulation method and flexible semiconductor device”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of electronic device packaging materials, and in particular to an organosiloxane monomer, an organosiloxane sealant and a preparation method thereof, a thin film packaging method and a flexible semiconductor device. Background Art

[0004] Because the material of OLED devices is extremely sensitive to water vapor and oxygen in the daily environment, they must be encapsulated to ensure their normal service life. If the device's service life is to reach more than 10,000 hours, the water vapor transmission rate of the device must be less than 10 -6 g / m 2 This poses a significant challenge to the sealing structure of display devices. Furthermore, to meet practical application requirements, OLED device encapsulation materials must not only have low water and oxygen permeability, but also meet multiple requirements such as low shrinkage, strong adhesion to the substrate, and high light transmittance.

[0005] Patent CN109251584A discloses an ink composition with high heat resistance and high light transmittance. The ink composition is prepared by combining a silicon-containing monomer with a special rigid group structure with a photocurable monomer and a photoinitiator. Although this reduces the excessive volume shrinkage of the organic ink composition during curing to a certain extent, the performance test results of the embodiment show that the water vapor transmission rate can only reach 2.6g / m 2 ·day, it still cannot meet the requirements of OLED device packaging materials.

[0006] Therefore, developing an OLED device packaging material that simultaneously meets the requirements of low water vapor transmission rate, low shrinkage rate, good adhesion and high light transmittance has important research significance and application value.

[0007] Summary of the Invention

[0008] To solve the above problems, the present invention provides an organosiloxane monomer and an organosiloxane sealant using the organosiloxane monomer.

[0009] Another object of the present invention is to provide a method for preparing the above-mentioned organosiloxane sealant.

[0010] Another object of the present invention is to provide a thin film packaging method for a flexible semiconductor device.

[0011] Another object of the present invention is to provide a flexible semiconductor device manufactured using the above-mentioned thin film encapsulation method. To achieve the above-mentioned object, the technical solution of the present invention is as follows:

[0012] The present invention provides an organosiloxane monomer, the structure of which is shown in general formula (I):

[0013] wherein R1, R2, R3, R4, R5, and R6 are each independently substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted C 1-30 Alkylene ether group, substituted or unsubstituted C 6-30 Aryl, substituted or unsubstituted C 7-30 one of an aralkyl group and a substituted or unsubstituted fluoroalkyl group;

[0014] X1 and X2 are each independently substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted C 1-30 Alkylene ether group, substituted or unsubstituted C 6-30 Arylene, and substituted or unsubstituted C 7-30 One of the arylalkylene groups;

[0015] Y1 and Y2 are each independently one of the following structures:

[0016] Z1 and Z2 are each independently one of the following structures:

[0017] wherein B1, B2, B3, B4, B5, B6, and B7 are each independently hydrogen, substituted or unsubstituted C 1-30 of alkyl.

[0018] The present invention also provides an organosiloxane sealant comprising the following components in parts by weight: 5-70 parts of the organosiloxane monomer, 15-80 parts of a reactive diluent, and 0.1-10 parts of a photoinitiator.

[0019] The present invention also provides a method for preparing the above-mentioned organosiloxane sealant, comprising the following steps: mixing an organosiloxane monomer, a reactive diluent and a photoinitiator in a nitrogen atmosphere under light-proof conditions, and soaking them to obtain the organosiloxane sealant.

[0020] The present invention also provides a thin film packaging method for a flexible semiconductor device, comprising the following steps:

[0021] S1: Integrating semiconductor components on a flexible substrate;

[0022] S2: depositing a layer of inorganic material on the surface of the semiconductor element in S1 to obtain a first inorganic layer with a thickness of 5-1000 nm;

[0023] S3: depositing a layer of the organic siloxane sealant on the surface of the inorganic layer in S2, and then curing it with ultraviolet light to obtain an organic layer;

[0024] S4: depositing another layer of inorganic material on the surface of the organic layer in S3 to obtain another second inorganic layer with a thickness of 5-1000 nm, thereby achieving thin film encapsulation of the semiconductor element;

[0025] Wherein, the inorganic materials in S2 and S4 are each independently at least one of silicon nitride, titanium oxide, aluminum oxide and silicon oxide.

[0026] The present invention also provides a flexible semiconductor device prepared using the above-mentioned thin film encapsulation method, comprising: a flexible substrate, a semiconductor element and a thin film encapsulation structure, wherein the semiconductor element is arranged on one side of the flexible substrate, and the thin film encapsulation structure comprises a first inorganic layer, an organic layer and a second inorganic layer, and the first inorganic layer, the organic layer and the second inorganic layer are stacked in sequence on a surface of the semiconductor element facing away from the flexible substrate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides an organosiloxane monomer with a specific group structure that can be used as the main component of a flexible semiconductor device encapsulation material. The material exhibits low water vapor permeability, strong adhesion to silicon nitride substrates, and high light transmittance, making it effective for encapsulating flexible semiconductor devices. Furthermore, by manipulating the specific structure of the organosiloxane monomer, the surface tension of the material is effectively improved, making the encapsulation material well-suited for inkjet printing and improving encapsulation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a schematic structural diagram of a thin film encapsulation structure provided in the present invention.

[0030] FIG2 is a schematic structural diagram of a flexible semiconductor device provided in the present invention.

[0031] FIG3 is a flow chart showing the formation of an organic layer by the organosiloxane sealant provided in the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below with reference to the examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Experimental methods in the following examples where specific conditions are not specified are generally performed in accordance with conventional conditions in the art or the conditions recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from conventional markets. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed in the present invention.

[0033] The present invention provides an organosiloxane monomer, the structure of which is shown in general formula (I):

[0034] wherein R1, R2, R3, R4, R5, and R6 are each independently substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted C 1-30 Alkylene ether group, substituted or unsubstituted C 6-30 Aryl, substituted or unsubstituted C 7-30 one of an aralkyl group and a substituted or unsubstituted fluoroalkyl group;

[0035] X1 and X2 are each independently substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted C 1-30 Alkylene ether group, substituted or unsubstituted C 6-30 Arylene, substituted or unsubstituted C 7-30 One of the arylalkylene groups;

[0036] Y1 and Y2 are each independently one of the following structures:

[0037] Z1 and Z2 are each independently one of the following structures:

[0038] wherein B1, B2, B3, B4, B5, B6, and B7 are each independently hydrogen, substituted or unsubstituted C 1-30 of alkyl.

[0039] The present invention provides an organosiloxane monomer with a unique structure. By introducing R1, R2, R3, R4, R5, and R6 groups into the Si-O chain, as well as reactive functional groups Y1, Y2, and Z1, Z2, the organosiloxane monomer exhibits increased reactivity, strong adhesion to substrates, and significantly enhanced hydrogen bonding within the molecules, thereby increasing the surface tension of the organosilicon, making it more conducive to inkjet printing. Application of this organosiloxane monomer in an organosiloxane sealant results in low water vapor transmission, strong adhesion to silicon nitride substrates, and high light transmittance, making it effective for the encapsulation of flexible semiconductor devices.

[0040] Preferably, the organosiloxane monomer is one of the following compounds A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8, A-9, A-10, A-11, A-12, A-13 or A-14:

[0041] The present invention also provides an organosiloxane sealant comprising the following components in parts by weight: 5-70 parts of the organosiloxane monomer, 15-80 parts of a reactive diluent, and 0.1-10 parts of a photoinitiator.

[0042] Further preferably, the organosiloxane sealant comprises the following components in parts by weight: 50 parts of the organosiloxane monomer, 47 parts of a reactive diluent, and 3 parts of a photoinitiator.

[0043] Preferably, the reactive diluent is at least one of an epoxy diluent and an acrylate diluent.

[0044] Further preferably, the epoxy diluent is 1,4-butanediol diglycidyl ether, 1,3-propylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, 1,7-heptanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, trimethylolpropane triglycidyl ether and 1,4-bis[(glycidyloxy)methyl]cyclohexane, 1,9-nonanediol diglycidyl ether, bisphenol A diglycidyl ether, 1,10-decanediol diglycidyl ether, 1,11-undecanediol diglycidyl ether, 1,12-dodecanediol diglycidyl ether, 1,13-tridecanediol diglycidyl ether , 1,14-tetradecanediol diglycidyl ether, bis(7-oxabicyclo[4.1.0]3-heptylmethyl)adipate, 1,15-pentadecanediol diglycidyl ether, neopentyl glycol diglycidyl ether, dipropylene glycol diglycidyl ether, ethylene glycol diglycidyl ether, p-tert-butylphenol diglycidyl ether, benzyl alcohol glycidyl ether, o-cresol glycidyl ether, di[(3,4-epoxy-6-methylcyclohexyl)methyl]adipate, ethylene glycol diglycidyl ether, 1,2-epoxyhexadecane, 3,7-bis(3-oxetane)-5-oxononane, trimethylolpropane triglycidyl ether, 3-ethyl-3-[(2-ethylhexyloxy)methyl]butylene oxide, etc.

[0045] The acrylate diluent is an alkanediol di(meth)acrylate having a carbon number of 2 or more and 20 or less (the alkane is a chain compound and a saturated hydrocarbon), for example, 1,17-heptadecanediol di(meth)acrylate, 1,3-cyclohexanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,20-eicosanediol di(meth)acrylate, 1,11-undecanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,15-pentadecanediol di(meth)acrylate, 1,13-tridecanediol di(meth)acrylate, 1,7-octanediol di(meth)acrylate, 1,2-butanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, di(meth)acrylate, 1,18-octadecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 2,4-diethyl-1,5-pentanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,19-nonadecanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and the like.

[0046] The acrylate diluent may also be an alkanediol di(meth)acrylate (alkane is a cyclic compound) having a carbon number of 4 or more and 20 or less, for example, 1,2-cyclohexanediol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, etc.

[0047] Preferably, the photoinitiator is at least one of acylphosphine oxide, α-hydroxyketone, α-aminoketone and glyoxylate.

[0048] Further preferably, the photoinitiator is 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 4,6-trimethylbenzoyldimethoxyphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, benzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiethoxyphenylphosphine oxide, benzoyldiethoxyphosphine oxide, benzophenone and its derivatives, benzyl and its derivatives, anthraquinone and its derivatives, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, diethoxyacetophenone, 4-tert-butyltrichloroacetophenone, 2-dimethylaminoethyl benzoate, p-dimethylaminoethyl benzoate, diphenyl disulfide, thioxanthone and its derivatives, Camphorquinone, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid-2-bromoethyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid-2-methyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid chloride, 2 -methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, α-aminoalkylphenone derivatives, phenyl-glyoxylic acid-methyl ester or oxy-phenyl-acetic acid 2-[2-oxy-2-phenyl-ethoxy-ethoxy]-ethyl ester and oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester.

[0049] The present invention also provides a method for preparing the above-mentioned organosiloxane sealant, comprising the following steps: mixing and immersing an organosiloxane monomer, a reactive diluent and a photoinitiator in a nitrogen atmosphere under light-proof conditions to obtain the organosiloxane sealant.

[0050] Preferably, the mixing time is 2-3 hours, and the soaking step is to soak in activated 4A molecular sieve for 30-50 hours.

[0051] In addition, the present invention also provides a thin film packaging method for a flexible semiconductor device, comprising the following steps:

[0052] S1: Integrating semiconductor components on a flexible substrate;

[0053] S2: depositing a layer of inorganic material on the surface of the semiconductor element in S1 to obtain a first inorganic layer with a thickness of 5-1000 nm;

[0054] S3: depositing a layer of the above-mentioned organosiloxane sealant on the surface of the inorganic layer described in S2, and then curing it with ultraviolet light to obtain an organic layer;

[0055] S4: depositing another layer of inorganic material on the surface of the organic layer in S3 to obtain another second inorganic layer with a thickness of 5-1000 nm, thereby achieving thin film encapsulation of the semiconductor element;

[0056] Wherein, the inorganic material in steps S2 and S4 is independently at least one of silicon nitride, titanium oxide, aluminum oxide and silicon oxide.

[0057] In one embodiment, the semiconductor element is one of an OLED, a Micro-LED, a silicon-based semiconductor element, an AsGa semiconductor element, or a gallium phosphide semiconductor element.

[0058] The present invention also provides a flexible semiconductor device manufactured using the above-mentioned thin-film encapsulation method, comprising a flexible substrate, a semiconductor element, and a thin-film encapsulation structure. The semiconductor element is disposed on one side of the flexible substrate. The thin-film encapsulation structure comprises a first inorganic layer, an organic layer, and a second inorganic layer, which are sequentially stacked on a surface of the semiconductor element facing away from the flexible substrate. A schematic structural diagram of the thin-film encapsulation structure is shown in Figure 1.

[0059] Specifically, the inorganic material is first deposited on the surface of the semiconductor element using chemical vapor deposition to form a first inorganic layer. A layer of the organosiloxane sealant is then sprayed onto the first inorganic layer using an inkjet method to form the organic layer. A second inorganic layer is then deposited onto the organic layer to obtain the flexible semiconductor device. A schematic structural diagram of the resulting flexible semiconductor device is shown in Figure 2.

[0060] The process of obtaining the organic layer by inkjet is shown in Figure 3. The inkjet step includes using the above-mentioned organic silicone sealant as ink ink, using a flexible substrate to align and discharge the ink, the ink contacts the flexible substrate, spreads and flows on the flexible substrate, and then cures into a film under ultraviolet light curing (UV LED) conditions to obtain the organic layer.

[0061] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0062] (A) Organosiloxane monomer: see A-2, A-5, A-6, A-7, A-11, A-13, A-14 above;

[0063] (B) Reactive diluent: 1,8-octanediol diglycidyl ether;

[0064] (C) Photoinitiators: Irgacure 250 and Irgacure 127.

[0065] The organosiloxane monomers are self-made. Here, only the preparation method of A-13 is specifically described. The preparation methods of the other organosiloxane monomers can be prepared using methods similar to that of A-13. The preparation reaction equation of A-13 is as follows:

[0066] The specific preparation process is as follows:

[0067] To a 10L reaction flask equipped with a reflux system, add 416g of compound a, 285g of allylamine b, and 5L of ethyl acetate. Add 3g of Karstedt catalyst, heat to 80°C, and react for 6 hours. Cool to room temperature, filter out the catalyst, and then distill under reduced pressure to remove the solvent and excess allylamine, yielding 640g of product c. Product c and compound d were then stirred in 5L of toluene at 50°C for 6 hours to obtain the final product, A-13.

[0068] The preparation method of the organosiloxane sealant in each embodiment of the present invention is as follows:

[0069] In a glove box (N2 atmosphere), organosiloxane monomer (50 parts), reactive diluent 1,8-octanediol diglycidyl ether (47 parts), and photoinitiators Irgacure 250 and Irgacure 127 (3 parts) were added to a 500 mL volumetric flask, mixed vigorously for 2 h in the dark, and then soaked in activated 4A molecular sieves for 48 h to prepare an organosiloxane sealant.

[0070] The prepared organosiloxane sealant was inkjet-coated onto a substrate to form a 10 μm film. After UV curing, the film was tested for water vapor transmission rate (WVTR). WVTR was measured using a water permeability meter (Model 3, MOCON) at 40°C and 100% relative humidity for 24 hours.

[0071] Examples 1-8

[0072] The present invention provides a series of organosiloxane sealants according to embodiments. The formulations and performance test results are shown in Table 1.

[0073] Table 1 Formula (parts) and performance test results of the organosiloxane sealant in the embodiment

[0074] Comparative Example 1

[0075] In Comparative Example 1, no organosiloxane monomer was added, and 97 parts of active diluent 1,8-octanediol diglycidyl ether was added, and the rest was the same as in Example 1. The water vapor permeability of the product prepared in Comparative Example 1 was 9x10 -3 g / m 2 ·day.

[0076] As demonstrated in Examples 1-8 and Comparative Example 1, the organosiloxane monomers with unique structures provided by the present invention can effectively reduce the water vapor transmission rate of organosiloxane sealants. These materials can be used as the primary component of flexible semiconductor device encapsulation materials. These materials exhibit low water vapor transmission rates, strong adhesion to silicon nitride substrates, and high light transmittance, making them effective for the encapsulation of flexible semiconductor devices. Furthermore, by manipulating the specific structure of the organosiloxane monomers, the surface tension of the material is effectively improved, making the encapsulation material well-suited for inkjet printing and improving encapsulation efficiency.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An organosiloxane monomer, characterized in that: The structure of the organosiloxane monomer is shown in general formula (I): wherein R1, R2, R3, R4, R5, and R6 are each independently substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted C 1-30 Alkylene ether group, substituted or unsubstituted C 6-30 Aryl, substituted or unsubstituted C 7-30 One of an aralkyl group, and a substituted or unsubstituted fluoroalkyl group; X1 and X2 are each independently substituted or unsubstituted C 1-20 Alkylene, substituted or unsubstituted C 1-30 Alkylene ether group, substituted or unsubstituted C 6-30 Arylene, and substituted or unsubstituted C 7-30 One of the arylalkylene groups; Y1 and Y2 are each independently one of the following structures: Z1 and Z2 are each independently one of the following structures: wherein B1, B2, B3, B4, B5, B6, and B7 are each independently hydrogen, or substituted or unsubstituted C 1-30 of alkyl.

2. The organosiloxane monomer according to claim 1, characterized in that The organosiloxane monomer is one of the following compounds A-1, A-2, A-3, A-4, A-5, A-6, A-7, A-8, A-9, A-10, A-11, A-12, A-13 or A-14:

3. An organosiloxane sealant, characterized in that: The composition comprises the following components in parts by weight: 5-70 parts of the organosiloxane monomer according to any one of claims 1 to 2, 15-80 parts of a reactive diluent, and 0.1-10 parts of a photoinitiator.

4. The organosiloxane sealant according to claim 3, characterized in that The active diluent is at least one of an epoxy diluent and an acrylate diluent.

5. The organosiloxane sealant according to claim 3, characterized in that The photoinitiator is at least one of acylphosphine oxide, α-hydroxyketone, α-aminoketone and glyoxylic acid ester.

6. A method for preparing an organosiloxane sealant as claimed in any one of claims 3 to 5, characterized in that: The method comprises the following steps: mixing and soaking an organic siloxane monomer, an active diluent and a photoinitiator under a nitrogen atmosphere in a light-proof condition to obtain the organic siloxane sealant.

7. The method for preparing an organosiloxane sealant according to claim 6, characterized in that: The mixing time is 2-3 hours, and the soaking step is to soak the activated 4A molecular sieve for 30-50 hours.

8. A thin film packaging method for a flexible semiconductor device, characterized in that: The steps include: S1: Integrating semiconductor components on flexible substrates; S2: depositing a layer of inorganic material on the surface of the semiconductor element in S1 to obtain a first inorganic layer with a thickness of 5-1000 nm; S3: depositing a layer of the organic siloxane sealant as described in any one of claims 3 to 5 on the surface of the inorganic layer described in S2, and then curing it with ultraviolet light to obtain an organic layer; S4: depositing another layer of inorganic material on the surface of the organic layer in S3 to obtain another second inorganic layer with a thickness of 5-1000 nm, thereby realizing thin film encapsulation of the semiconductor element; Wherein, the inorganic materials in S2 and S4 are each independently at least one of silicon nitride, titanium oxide, aluminum oxide and silicon oxide.

9. The thin film encapsulation method according to claim 8, characterized in that: The semiconductor element is an OLED, a Micro-LED, a silicon-based semiconductor element, an AsGa semiconductor element or a gallium phosphide semiconductor element.

10. A flexible semiconductor device, characterized in that: Prepared by the thin film encapsulation method according to any one of claims 8 to 9, comprising: Flexible substrates; A semiconductor element is disposed on one side of the flexible substrate; The thin film packaging structure comprises a first inorganic layer, an organic layer and a second inorganic layer, wherein the first inorganic layer, the organic layer and the second inorganic layer are sequentially stacked on a surface of the semiconductor element away from the flexible substrate.

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