Composition for manufacturing protective film and including the same

Abstract

The present invention relates to a composition for manufacturing a protective film and an optical module comprising the same. The composition for manufacturing a protective film according to the present invention comprises a copolymer containing a polyalkylene glycol side chain and a water-soluble cellulose derivative main chain, wherein at least one of the polyalkylene glycol terminals is covalently bonded to a repeating unit of the water-soluble cellulose derivative.

Description

Technology Field

[0001] The present invention relates to a composition for manufacturing a protective film and an optical module comprising the same. Background Technology

[0002] Optical modules are used in a wide range of electro-optical products, including mobile phones, laptops, security cameras, automobiles, and Internet of Things (IoT) sensors, and are being developed in various forms depending on the types of components and packaging methods. In particular, to achieve cost reduction, it is a critical task to lower the product defect rate caused by contamination or foreign substances in the micro-lenses included in the image sensor during the manufacturing and assembly processes of optical modules.

[0003] As a method to prevent this, a conventional technique is known in which a protective film composed mainly of an organic polymer is formed on the micro-lens portion of an image sensor chip, the image sensor is bonded to a substrate to assemble an optical module, and the protective film is removed after assembly is complete.

[0004] However, conventional protective films are environmentally unfriendly because they use organic solvents as the primary solvent in the film composition, requiring wastewater treatment; furthermore, it is difficult to quickly and completely remove the film using water alone during the subsequent cleaning process.

[0005] Therefore, there is a need for the development of a protective film manufacturing composition and a protective film manufactured therefrom, which can form a uniform and reliable protective film on a substrate of a device using an environmentally friendly water-soluble polymer with water as the main solvent, and at the same time have the performance to be rapidly removed by water during a cleaning process. Prior art literature

[0006] Korean Published Patent No. 2021-0077102 The problem to be solved

[0007] One aspect of the present invention is to provide a composition for manufacturing a protective film that has excellent coating properties and can form a uniform protective film.

[0008] Another aspect of the present invention is to provide a composition for manufacturing a protective film capable of manufacturing a protective film having appropriate hardness.

[0009] Another aspect of the present invention is to provide a composition for manufacturing a protective film such that the manufactured protective film can be easily and quickly removed by water. means of solving the problem

[0010] The composition for manufacturing a protective film according to the present invention comprises a copolymer containing a polyalkylene glycol side chain and a water-soluble cellulose derivative main chain, wherein at least one of the polyalkylene glycol terminals is covalently bonded to a repeating unit of the water-soluble cellulose derivative.

[0011] According to one embodiment, the polyalkylene glycol terminal may be bonded to the repeating unit of the water-soluble cellulose derivative with a urethane group.

[0012] According to one embodiment, the polyalkylene glycol may include one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, polypentamethylene glycol, ethylene oxide-propylene oxide copolymer, and propylene oxide-butylene oxide copolymer.

[0013] According to one embodiment, the weight-average molecular weight of the polyalkylene glycol may be 400 to 6000.

[0014] According to one embodiment, the water-soluble cellulose derivative may include one or more selected from the group consisting of hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose sodium salt, and carboxymethylhydroxyethylcellulose.

[0015] According to one embodiment, the weight-average molecular weight of the cellulose water-soluble derivative may be 2,000 to 120,000.

[0016] According to one embodiment, the copolymer may be water-soluble at a concentration of 30 weight% or less at 25°C.

[0017] According to one embodiment, the viscosity measured at 25°C of an aqueous solution in which the copolymer is dissolved at 10% by weight may be 1 to 500 cps.

[0018] The protective film according to the present invention is manufactured from the above-described composition for manufacturing a protective film.

[0019] An optical module according to the present invention comprises a circuit board, an image sensor chip disposed on the circuit board, a housing for accommodating the image sensor chip, and an optical lens assembly mounted on the housing, wherein the image sensor chip comprises a micro-lens portion and a protective film disposed on one surface of the micro-lens portion, and the protective film is formed from the above-described composition for manufacturing a protective film, and the relative standard deviation of the protective film thickness in a 1mm x 1mm area of ​​the protective film is less than 1%.

[0020] According to one embodiment, the optical module includes a camera module, and the ShoreD hardness of the protective film measured according to ASTM D2240 may be 40 or higher.

[0021] A method for manufacturing an optical module according to the present invention comprises: S1) applying a composition for manufacturing a protective film according to claim 1 to one surface of a micro-lens portion; S2) drying the composition for manufacturing a protective film to manufacture an image sensor chip having a protective film formed thereon; S3) bonding the image sensor chip to a circuit board; S4) removing the protective film of the image sensor chip; S5) installing a housing for accommodating the image sensor chip; and S6) mounting an optical lens on the housing.

[0022] According to one embodiment, the step of removing the protective film in step S4) may involve applying a cleaning solvent to one surface of the micro-lens portion included in the image sensor chip.

[0023] According to one embodiment, the cleaning solvent of step S4) may include water. Effects of the invention

[0024] The present invention can provide a composition for manufacturing a protective film that has excellent coating properties and can form a uniform protective film.

[0025] In addition, the present invention can provide a composition for manufacturing a protective film capable of manufacturing a protective film having appropriate hardness.

[0026] In addition, the present invention can provide a composition for manufacturing a protective film such that the manufactured protective film can be easily and quickly removed by water. Brief explanation of the drawing

[0027] FIG. 1 illustrates the process of manufacturing a protective film by applying a composition for manufacturing a protective film onto an image sensor chip using a dotting method. FIG. 2 illustrates a state in which the protective film is uniformly formed over the entire surface. FIG. 3 illustrates a state in which the protective film is non-uniformly formed in some areas. FIG. 4 illustrates a state in which the protective film is non-uniformly formed overall. FIG. 5 illustrates the state of the chip surface after the protective film formed on the image sensor chip has been removed through a cleaning process. Specific details for implementing the invention

[0028] Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0029] In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field.

[0030] In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0031] In this specification, expressions such as “include” or “comprising” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0032] Unless otherwise specifically defined in this specification, % units mean weight %.

[0033] In this specification, terms such as 'top', 'upper', 'upper surface', 'lower', 'lower surface', 'lower surface', and 'side surface' are based on the drawings and may actually vary depending on the direction in which the elements or components are arranged.

[0034] Additionally, throughout the specification, when it is said that one part is 'connected' to another part, this includes not only cases where they are 'directly connected,' but also cases where they are 'indirectly connected' with other elements in between.

[0035] The numerical ranges used herein include lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of which are limited, and all possible combinations of upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in this specification, values ​​outside the numerical range that may occur due to experimental error or rounding are also included in the defined numerical range.

[0036] Unless otherwise specifically defined in this specification, “about” may be considered to be a value within 30%, 25%, 20%, 15%, 10%, or 5% of the specified value.

[0037] In this specification, average molecular weight may be measured by gel permeation chromatography (GPC) and may mean weight-average molecular weight unless otherwise defined.

[0038] In this specification, the ShoreD hardness of the protective film may be measured according to ASTM D2240.

[0039] In this specification, an optical module may encompass various sensor modules having the function of collecting, detecting, and processing light. Specifically, an optical module may include a camera module.

[0040] In this specification, the thickness of the protective film may refer to the average thickness obtained by averaging thickness values ​​measured at five points on the protective film. Additionally, the standard deviation of the thickness of the protective film may refer to the relative standard deviation (RSD, %) of the average thickness of the protective film.

[0041] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0042] The composition for manufacturing a protective film according to the present invention comprises a copolymer containing a polyalkylene glycol side chain and a water-soluble cellulose derivative main chain, wherein at least one of the polyalkylene glycol terminals is covalently bonded to a repeating unit of the water-soluble cellulose derivative.

[0043] According to one embodiment, the weight-average molecular weight of the copolymer may be 4,000 to 180,000. For example, the weight-average molecular weight of the copolymer may be 4,000 or more, 12,000 or more, 20,000 or more, or 28,000 or more, and may also be 180,000 or less, 140,000 or less, 100,000 or less, or 60,000 or less. Specifically, the weight-average molecular weight of the copolymer may be 4,000 to 180,000, 4,000 to 140,000, 4,000 to 100,000, 4,000 to 60,000, 12,000 to 140,000, 12,000 to 100,000, 12,000 to 60,000, 20,000 to 100,000, 20,000 to 60,000, or 28,000 to 60,000. When the weight-average molecular weight of the copolymer satisfies the range described above, the viscosity of the copolymer aqueous solution measured at room temperature is within an appropriate range, the water solubility of the protective film composition is improved, and the applicability to the substrate is increased, which may be advantageous for forming a uniform protective film from the composition containing the copolymer.

[0044] According to one embodiment, the copolymer may be a graft copolymer. Specifically, it may be a graft structure in which a water-soluble cellulose derivative forms a main chain and a polyalkylene glycol forms a side chain, and the polyalkylene glycol side chain may have a graft structure in which one or more of the polyalkylene glycol side chains are covalently bonded to one molecule of the water-soluble cellulose derivative main chain. For example, one or more, two or more, or three or more, and indefinitely 50 or fewer polyalkylene glycol side chains may be covalently bonded to one molecule of the water-soluble cellulose derivative main chain, but are not limited thereto.

[0045] According to another embodiment, the copolymer may be a branched copolymer. Specifically, it may have a branched structure in which a water-soluble cellulose derivative forms a main chain and a polyalkylene glycol forms a side chain, and the copolymer may partially have a structure in which both ends of the polyalkylene glycol are covalently bonded to the main chain of the water-soluble cellulose derivative, within a range in which the copolymer is soluble in a solvent.

[0046] According to one embodiment, the polyalkylene glycol terminus may be one or more selected from a urethane group (-NH-COO-), a carbonate group (-O-COO-), an ester group (-COO-), an ether group (-O-), an acetal group (-O-CH2-O-), an amide group (-CONH-), a phosphate group (-O-PO(OR)-O-), or a sulfonic acid ester group (-SO2-O-) bonded to the repeating unit of the cellulose derivative. For example, the polyalkylene glycol terminus may be bonded to the repeating unit of the water-soluble cellulose derivative by a urethane group.

[0047] According to one embodiment, the polyalkylene glycol may be poly(C1-C6)alkylene glycol, specifically poly(C1-C4)alkylene glycol. For example, the polyalkylene glycol may include one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, polypentamethylene glycol, ethylene oxide-propylene oxide copolymer, and propylene oxide-butylene oxide copolymer.

[0048] According to one embodiment, the weight-average molecular weight of the polyalkylene glycol may be 400 to 6000. For example, the weight-average molecular weight of the polyalkylene glycol may be 400 or more, 600 or more, 800 or more, or 1000 or more, and may also be 6000 or less, 5000 or less, 4000 or less, or 3000 or less. Specifically, the weight-average molecular weight of the polyalkylene glycol may be 400 to 6000, 400 to 5000, 400 to 4000, 400 to 3000, 600 to 5000, 600 to 4000, 600 to 3000, 800 to 4000, 800 to 3000, or 1000 to 3000.

[0049] According to one embodiment, the water-soluble cellulose derivative may include one or more selected from the group consisting of hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose sodium salt, and carboxymethylhydroxyethylcellulose.

[0050] According to one embodiment, the weight-average molecular weight of the cellulose water-soluble derivative may be 2,000 to 120,000. For example, the weight-average molecular weight of the cellulose water-soluble derivative may be 2,000 or more, 3,000 or more, 4,000 or more, or 5,000 or more, and may also be 120,000 or less, 100,000 or less, 80,000 or 60,000 or less. Specifically, the weight-average molecular weight of the cellulose water-soluble derivative may be 2,000 to 120,000, 2,000 to 100,000, 2,000 to 80,000, 2,000 to 60,000, 3,000 to 100,000, 3,000 to 80,000, 3,000 to 60,000, 4,000 to 80,000, 4,000 to 60,000, or 5,000 to 60,000.

[0051] When the weight-average molecular weight of the polyalkylene glycol and the weight-average molecular weight of the cellulose water-soluble derivative satisfy the ranges described above, the viscosity measured at room temperature of the copolymer aqueous solution containing the polyalkylene glycol and the cellulose water-soluble derivative is within an appropriate range, and it may be advantageous for a uniform protective film to be formed from the composition containing the copolymer.

[0052] According to one embodiment, the copolymer may be water-soluble at a concentration of 30 weight% or less at 25°C. For example, the copolymer may be water-soluble at a concentration of 0.1 to 30 weight%, 0.2 to 30 weight%, 0.5 to 30 weight%, 0.2 to 28 weight%, 0.5 to 26 weight%, 0.2 to 26 weight%, or 0.5 to 26 weight% at 25°C.

[0053] According to one embodiment, the viscosity measured at 25°C of an aqueous solution in which the copolymer is dissolved at 10% by weight may be 1 to 500 cps. For example, the viscosity measured at 25°C of an aqueous solution in which the copolymer is dissolved at 10% by weight may be 1 cps or more, 2 cps or more, 3 cps or more, or 4 cps or more, and may also be 500 cps or less, 490 cps or less, 480 cps or less, or 470 cps or less. Specifically, it may be 1 to 500 cps, 1 to 490 cps, 1 to 480 cps, 1 to 470 cps, 2 to 490 cps, 2 to 480 cps, 2 to 470 cps, 3 to 480 cps, 3 to 470 cps, or 4 to 470 cps. If the viscosity measured at 25°C of an aqueous solution in which the copolymer is dissolved at 10% by weight satisfies the range described above, the dispersibility and solubility of the copolymer in the aqueous solution are excellent, so a protective film can be uniformly formed. In addition, the change in viscosity of the composition over time is not significant, so storage stability can be excellent.

[0054] According to one embodiment, the composition for manufacturing the protective film may include water as a solvent.

[0055] As the solvent, water may be included, for example, in an amount of 50% or more, 55% or more, or 60% or more based on the total weight of the composition for manufacturing a protective film, and may also be included in an amount of 90% or less, 85% or less, or 80% or less. Specifically, as the solvent, water may be included in an amount of 50 to 90%, 50 to 85%, 50 to 80%, 55 to 85%, 55 to 80%, or 60 to 80% based on the total weight of the composition for manufacturing a protective film.

[0056] Meanwhile, the composition for manufacturing the protective film may additionally include an organic solvent to control viscosity, etc. For example, the organic solvent may be a polar protic solvent, and specifically, may be an alcohol-based solvent. For example, the organic solvent may include one or more selected from the group consisting of methanol, ethanol, isopropyl alcohol, and tert-butyl alcohol. Specifically, the organic solvent may include tert-butyl alcohol.

[0057] The above organic solvent may be included in an amount such that, for example, based on the total weight of the composition for manufacturing the protective film, it is 5 to 40 weight%, 5 to 35 weight%, 5 to 30 weight%, 5 to 25 weight%, 7 to 35 weight%, 7 to 30 weight%, 7 to 25 weight%, 9 to 30 weight%, or 9 to 25 weight%.

[0058] Meanwhile, the organic solvent may volatilize and be removed during the drying step for manufacturing the protective film, so that the organic solvent may not substantially remain in the protective film finally formed on the device.

[0059] Meanwhile, the above composition for manufacturing the protective film may additionally include a surfactant as needed. For example, the surfactant may be water-soluble. In addition, since the water-soluble surfactant lowers surface tension, the coating properties of the above composition for manufacturing the protective film may be improved by adding the surfactant.

[0060] The above-mentioned water-soluble surfactant may be included in an amount such that, based on the total weight of the composition for manufacturing the protective film, it is 0.1 to 10 wt%, 0.1 to 9.8 wt%, 0.1 to 9.6 wt%, 0.1 to 9.4 wt%, 0.2 to 9.8 wt%, 0.2 to 9.6 wt%, 0.2 to 9.4 wt%, 0.3 to 9.6 wt%, or 0.3 to 9.4 wt%. If the content of the surfactant satisfies the ranges described above, the applicability of the composition for manufacturing the protective film increases, and the protective film can be formed uniformly. In addition, the thermal stability of the composition for manufacturing the protective film increases, and the hardness of the manufactured protective film can be appropriate.

[0061] Meanwhile, the above composition for manufacturing the protective film may additionally include one or more additives known in the art as needed. For example, the above composition for manufacturing the protective film may additionally include an antifoaming agent as an additive to suppress bubble formation. For example, the antifoaming agent may be one or more compounds selected from the group consisting of polysiloxane, polyalkylsiloxane, and fluorinated polymer.

[0062] The protective film according to the present invention is manufactured from the above-described composition for manufacturing a protective film.

[0063] Since the above protective film is manufactured from a composition for manufacturing a protective film containing the copolymer, it has excellent heat resistance and can be formed as a uniform protective film by maintaining stability even at process temperatures of 100°C or higher. Furthermore, since no by-products are generated due to the cross-linking reaction of the copolymer even at high process temperatures, it can be easily removed by water during the cleaning step. In addition, since the copolymer is synthesized based on a water-soluble polymer, manufacturing it from a composition for manufacturing a protective film containing the copolymer makes it not only environmentally friendly but also superior in terms of economic efficiency compared to conventional organic solvent-based protective films. Moreover, since the composition for manufacturing a protective film is water-soluble, a uniform protective film can be easily manufactured over the entire surface of the micro-lens included in the image sensor chip with only a simple coating and drying process.

[0064] According to one embodiment, the thickness of the protective film may be, for example, 10 to 80 μm, 10 to 70 μm, 12 to 60 μm, 14 to 50 μm, 16 to 40 μm, 18 to 30 μm, or 20 to 30 μm. If the thickness of the protective film satisfies the above-described range, scratches on the protective film caused by mechanical shock that may occur during the image sensor chip bonding step described later can be suppressed. Accordingly, the micro-lens portion on the image sensor chip can be stably protected, thereby preventing the occurrence of defective products.

[0065] According to one embodiment, the relative standard deviation of the protective film thickness in a 1 mm x 1 mm area of ​​the protective film may be, for example, 5% or less, 3% or less, 1% or less, or 0.8% or less. When the relative standard deviation of the protective film thickness satisfies the ranges described above, the protective film may have a uniform thickness over the entire surface area of ​​the protective film. In addition, the protective film may be easily removed in the protective film removal process described later, so that no protective film residue remains.

[0066] An optical module according to the present invention comprises a circuit board, an image sensor chip disposed on the circuit board, a housing for accommodating the image sensor chip, and an optical lens assembly mounted on the housing, wherein the image sensor chip comprises a micro-lens portion and a protective film disposed on one surface of the micro-lens portion, and the protective film is formed from the above-described composition for manufacturing a protective film, and the relative standard deviation of the protective film thickness in a 1mm x 1mm area of ​​the protective film is less than 1%.

[0067] According to one embodiment, the optical module includes a camera module, and the ShoreD hardness of the protective film measured according to ASTM D2240 may be 40 or higher. For example, the ShoreD hardness of the protective film may be 40 or higher, 44 or higher, or 48 or higher, and may also be 70 or lower, 68 or lower, or 66 or lower. Specifically, the ShoreD hardness of the protective film may be 40 to 70, 40 to 68, 40 to 66, 44 to 68, 44 to 66, 48 to 68, or 48 to 66. If the ShoreD hardness of the protective film satisfies the above-described range, the micro-lens portion can be reliably protected during the optical module manufacturing process, and the time for removing the protective film in the water cleaning process described later can be shortened.

[0068] A method for manufacturing an optical module according to the present invention comprises: S1) applying a composition for manufacturing a protective film according to claim 1 to one surface of a micro-lens portion; S2) drying the composition for manufacturing a protective film to manufacture an image sensor chip having a protective film formed thereon; S3) bonding the image sensor chip to a circuit board; S4) removing the protective film of the image sensor chip; S5) installing a housing for accommodating the image sensor chip; and S6) mounting an optical lens on the housing.

[0069] One surface of the micro-lens portion may be a surface on which a protective film is formed, and the other surface of the micro-lens may be a surface opposite to the one surface of the micro-lens portion that contacts the front surface of the image sensor substrate. The rear surface of the image sensor substrate may be a surface that contacts the circuit board, and the front surface of the image sensor substrate may be a surface opposite to the rear surface of the image sensor substrate where the micro-lens portion is located.

[0070] According to one embodiment, in step S1), the composition for manufacturing the protective film may include water as a solvent. Specifically, the water as the solvent may be included in an amount of 50 to 90 weight%, 50 to 85 weight%, 50 to 80 weight%, 55 to 85 weight%, 55 to 80 weight%, or 60 to 80 weight% based on the total weight of the composition for manufacturing the protective film.

[0071] According to one embodiment, in step S1), the composition for manufacturing the protective film may be prepared by uniformly mixing by stirring in a mixing stirrer, for example, at 50 to 500 rpm, 120 to 400 rpm, 150 to 300 rpm, or 180 to 250 rpm.

[0072] According to one embodiment, in step S1), the solid content of the composition for manufacturing the protective film may be 1 to 30 weight%, 2 to 26 weight%, 3 to 22 weight%, 4 to 18 weight%, or 5 to 15 weight%.

[0073] According to one embodiment, in step S1), the application of the composition for manufacturing a protective film may be performed, for example, by dotting, dipping, spray coating, inkjet, dispensing, screen printing, or offset printing, or by using a doctor knife, slit coater, roll coater, curtain coater, or knife coater.

[0074] According to one embodiment, in step S2), the temperature at which the composition for manufacturing the protective film is dried may be, for example, 20 to 300 ℃. Specifically, the temperature at which the composition for manufacturing the protective film is dried may be 20 to 300 ℃, 20 to 290 ℃, 20 to 280 ℃, 20 to 270 ℃, 30 to 290 ℃, 30 to 280 ℃, 30 to 270 ℃, 40 to 280 ℃, or 40 to 270 ℃.

[0075] According to one embodiment, in step S2), the time for drying the composition for manufacturing the protective film may be, for example, 1 to 160 minutes. Specifically, the temperature for drying the composition for manufacturing the protective film may be 1 to 160 minutes, 1 to 150 minutes, 1 to 140 minutes, 2 to 160 minutes, 2 to 150 minutes, 2 to 140 minutes, 3 to 150 minutes, or 4 to 150 minutes.

[0076] According to one embodiment, the step of removing the protective film in step S4) may involve applying a cleaning solvent to one surface of the micro-lens portion included in the image sensor chip.

[0077] For example, the cleaning solvent may include water. Specifically, the water may be deionized water.

[0078] The above cleaning process may be carried out at room temperature (25℃) to 80℃.

[0079] The above cleaning process may be a process of removing a protective film by observing one side of the image sensor chip after immersing the image sensor chip in a cleaning solvent or spraying the cleaning solvent. Whether cleaning is complete can be determined by visually or microscopically observing one side of the image sensor chip to check for the presence of residue. After the removal of the solvent, a highly reliable protective film can be formed on the surface of the device by the composition for manufacturing a protective film according to the present invention due to its excellent film-forming ability. However, when immersed in water as a solvent or when water is sprayed onto the surface of the protective film, rapid swelling of the film occurs, which may cause it to be removed from the surface of the device. In particular, since the film is easily peeled off due to swelling, no residue is present, so a subsequent cleaning process may not be necessary, thereby providing excellent processability.

[0080] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0081] (Preparation Example 1)

[0082] Hydroxypropylmethylcellulose A-1 (weight-average molecular weight: 10,000) was dissolved in water for 6 hours at a temperature of 80°C, and then the temperature was lowered to room temperature to prepare 100g of a uniform 2 wt% aqueous solution of hydroxypropylmethylcellulose A-1 (HPMC 2 wt%, deionized water 98 wt%). 100g of a 2 wt% aqueous solution of polyethylene glycol (α,ω-Diisocyanato poly(ethylene glycol)) (weight-average molecular weight: 2,000) containing isocyanate groups at both ends was added to the hydroxypropylmethylcellulose A-1 aqueous solution in a dropwise manner. The mixture was stirred at 500 rpm for 4 hours at room temperature (25°C) to prepare copolymer B-1. The weight-average molecular weight of the prepared B-1 copolymer was 28,500.

[0083] (Preparation Example 2)

[0084] Copolymer B-2 was prepared in the same manner as in Preparation Example 1, except that hydroxypropylmethylcellulose A-2 (weight-average molecular weight: 20,000) was used instead of hydroxypropylmethylcellulose A-1 (weight-average molecular weight: 10,000) in Preparation Example 1. The weight-average molecular weight of the prepared B-2 copolymer was 45,000.

[0085] (Preparation Example 3)

[0086] Copolymer B-3 was prepared in the same manner as in Preparation Example 1, except that 50 g of a 2 wt% aqueous solution of polyethylene glycol (α,ω-Diisocyanato poly(ethylene glycol)) (weight average molecular weight: 2,000) containing isocyanate groups at both ends was added to a 2 wt% aqueous solution of hydroxypropylmethylcellulose A-1 (weight average molecular weight: 10,000) to prepare copolymer B-3. The weight average molecular weight of the prepared copolymer B-3 was 22,000.

[0087] (Preparation Example 4)

[0088] In Preparation Example 2, copolymer B-4 was prepared by the same method as in Preparation Example 1, except that 50 g of a 2 wt% aqueous solution of polyethylene glycol (α,ω-Diisocyanato poly(ethylene glycol) (weight average molecular weight: 2,000) containing isocyanate groups at both ends was added to a 2 wt% aqueous solution of hydroxypropylmethylcellulose A-2 (weight average molecular weight: 20,000). The weight average molecular weight of the prepared B-4 copolymer was 36,000.

[0089] (Examples and Comparative Examples)

[0090] 1) Preparation of a composition for manufacturing a protective film

[0091] The components listed in Table 1 were added to a mixing tank equipped with a stirrer in the specified amounts. The mixture was stirred at a speed of 200 rpm for 1 hour at room temperature to prepare a composition for manufacturing a protective film. At this time, the copolymer and hydroxypropylmethylcellulose synthesized in the preparation example were calculated based on the weight of the solid content.

[0092] Component A (weight%) Component B (weight%) Component C (weight%) t-butyl alcohol (wg%) Deionized water (weight%) Example 1 - - B-1 10 5 15 70 Example 2 - - B-2 10 5 15 70 Example 3 B-3 10 5 15 70 Example 4 B-4 10 5 15 70 Comparative Example 1 A-1 10 - - 5 15 70 Comparative Example 2 A-2 10 - - 5 15 70 Comparative Example 3 A-3 10 - - 5 15 70

[0093] A-1: Hydroxypropylmethylcellulose (Weight-average molecular weight: 10,000)

[0094] A-2: Hydroxypropylmethylcellulose (Weight-average molecular weight: 20,000)

[0095] A-3: Hydroxypropylmethylcellulose (Weight-average molecular weight: 35,000)

[0096] B-1: Copolymer of Preparation Example 1 (weight-average molecular weight: 28,500)

[0097] B-2: Copolymer of Preparation Example 2 (weight-average molecular weight: 45,000)

[0098] B-3: Copolymer of Preparation Example 3 (weight-average molecular weight: 22,000)

[0099] B-4: Copolymer of Preparation Example 4 (weight-average molecular weight: 36,000)

[0100] C: Silicone surfactant (Product name: BYK-337, Manufacturer: BYK)

[0101] 2) Preparation of protective film

[0102] On the upper front surface of the microlens portion of an 11 x 8 mm image sensor chip, a composition for manufacturing a protective film according to the example and comparative example was applied to the entire surface using a dotting method as shown in FIG. 1. The applied composition was dried in three consecutive stages using a hot air circulating oven (ESPEC Corp, SH-642) under conditions of 50°C for 5 minutes, 105°C for 60 minutes, and 150°C for 10 minutes to produce a protective film and an image sensor chip sample having the protective film formed thereon.

[0103] (Experimental Example: Verification of Physical Properties of the Protective Film)

[0104] (Experimental Example 1: Evaluation of Protective Film Uniformity)

[0105] The surface uniformity of the protective film formed on the image sensor chip samples according to the examples and comparative examples was confirmed through visual and microscopic observation according to FIGS. 2 to 4. The test results are shown in Table 2 below.

[0106] ○: The protective film is formed uniformly over the entire surface

[0107] △: An uneven pattern was observed in some areas of the protective layer.

[0108] X: An uneven pattern was observed across the entire area of ​​the protective layer.

[0109] (Experimental Example 2: Evaluation of protective film thickness and thickness deviation)

[0110] The thickness and thickness variation of the protective film formed on the image sensor chip samples according to the examples and comparative examples were confirmed through cross-sectional observation using a scanning electron microscope (SEM, JEOL, JSM-7610F).

[0111] The thickness of the protective film was calculated by averaging the values ​​measured at five points (the center of the chip and four corners) through cross-sectional images. The absolute standard deviation of the protective film thickness was calculated as the standard deviation of the average thickness of the values ​​measured at the five points, and the standard deviation of the protective film thickness was defined as the relative standard deviation calculated by Equation 1 below.

[0112] [Equation 1]

[0113] Relative standard deviation of protective film thickness (%) = (Absolute standard deviation of protective film thickness / Average thickness of protective film) × 100

[0114] The test results regarding the average thickness and thickness deviation of the protective film are shown in Table 2 below.

[0115] (Experimental Example 3: Evaluation of Protective Film Hardness)

[0116] The hardness of the protective film formed on the image sensor chip samples according to the examples and comparative examples was measured as Shore D hardness using a durometer (Bareiss) according to the ASTM D2240 method. The test results are shown in Table 2 below.

[0117] (Experimental Example 4: Evaluation of Cleaning Time of Protective Film)

[0118] The cleaning time, which is the time it takes for the protective film formed on the image sensor chip samples according to the examples and comparative examples to be washed away by water, was evaluated. Whether the cleaning of the formed protective film was complete was determined by checking for the absence of residue through visual and microscopic observation according to Fig. 5. The test results are shown in Table 2 below.

[0119] uniformity Thickness (㎛) Relative standard deviation (%) Shore D hardness Cleaning time (min) Example 1 ○ 27.2 0.74 57 6 Example 2 ○ 23.8 0.42 51 4 Example 3 ○ 29.1 0.76 58 9 Example 4 ○ 25.5 0.78 53 5 Comparative Example 1 △ 8.1 16.05 63 17 Comparative Example 2 △ 7.4 18.92 61 17 Comparative Example 3 △ 6.7 17.91 58 15

[0120] All protective films according to the examples were formed as uniform films. In addition, it was confirmed that the average thickness of the formed protective film was 20 to 30 μm, and the relative standard deviation of the thickness relative to the average thickness was less than 1%, indicating a very uniform thickness. Furthermore, it was confirmed that the protective film according to the examples had excellent cleaning power with water, with a cleaning time of less than 10 minutes.

[0121] In contrast, it was confirmed that the protective films according to Comparative Examples 1 to 3 were partially non-uniform, and that the relative standard deviation of the thickness of the manufactured protective films was 15% or more, resulting in thin protective films that were not uniform. In addition, it was confirmed that the protective films according to the Comparative Examples did not have excellent cleaning power with water, with a cleaning time of 15 minutes or more.

[0122] Meanwhile, the performance of the protective film was evaluated for copolymer B-5, which was prepared under the same reaction conditions as Preparation Example 1 using hydroxypropylmethylcellulose (weight-average molecular weight 35,000) used in Comparative Example 3 as a raw material. The protective film prepared from the composition containing the B-5 copolymer was found to have slightly lower uniformity and a larger standard deviation of thickness compared to the protective films of Examples 1 to 4. However, the washing time with water was found to be relatively good at 11 minutes.

Claims

Claim 1 A composition for manufacturing a protective film comprising a copolymer containing a polyalkylene glycol side chain and a water-soluble cellulose derivative main chain, wherein at least one of the polyalkylene glycol terminals is covalently bonded to a repeating unit of the water-soluble cellulose derivative. Claim 2 A composition for manufacturing a protective film according to claim 1, wherein the polyalkylene glycol terminal is bonded to a repeating unit of the water-soluble cellulose derivative by a urethane group. Claim 3 A composition for manufacturing a protective film according to claim 1, wherein the polyalkylene glycol comprises one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, polypentamethylene glycol, ethylene oxide-propylene oxide copolymer, and propylene oxide-butylene oxide copolymer. Claim 4 A composition for manufacturing a protective film according to claim 1, wherein the weight-average molecular weight of the polyalkylene glycol is 400 to 6000. Claim 5 A composition for manufacturing a protective film according to claim 1, wherein the water-soluble cellulose derivative comprises one or more selected from the group consisting of hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose sodium salt, and carboxymethylhydroxyethylcellulose. Claim 6 A composition for manufacturing a protective film according to claim 1, wherein the weight-average molecular weight of the water-soluble cellulose derivative is 2,000 to 120,000. Claim 7 A composition for manufacturing a protective film according to claim 1, wherein the copolymer is water-soluble at a concentration of 30 weight% or less at 25°C. Claim 8 A composition for manufacturing a protective film according to claim 1, wherein the viscosity measured at 25°C of an aqueous solution in which the copolymer is dissolved at 10% by weight is 1 to 500 cps. Claim 9 A protective film manufactured from a composition for manufacturing a protective film according to any one of claims 1 to 8. Claim 10 An optical module comprising: a circuit board; an image sensor chip disposed on the circuit board; a housing for receiving the image sensor chip; and an optical lens assembly mounted on the housing; wherein the image sensor chip comprises a micro-lens portion; and a protective film disposed on one surface of the micro-lens portion; wherein the protective film is formed from a composition for manufacturing a protective film according to claim 1, and the relative standard deviation of the protective film thickness in a 1mm x 1mm area of ​​the protective film is less than 1%. Claim 11 In claim 10, the optical module comprises a camera module, and the optical module has a ShoreD hardness of the protective film measured according to ASTM D2240 of 40 or higher. Claim 12 S1) a step of applying a composition for manufacturing a protective film according to claim 1 to one surface of a micro lens portion; S2) a step of manufacturing an image sensor chip having a protective film formed by drying the composition for manufacturing a protective film; S3) a step of bonding the image sensor chip to a circuit board; S4) a step of removing the protective film of the image sensor chip; S5) a step of installing a housing for accommodating the image sensor chip; and S6) a step of mounting an optical lens on the housing; comprising a method for manufacturing an optical module. Claim 13 A method for manufacturing an optical module according to claim 12, wherein in step S4) above, a cleaning solvent is applied to one surface of the micro-lens portion included in the image sensor chip to remove the protective film. Claim 14 A method for manufacturing an optical module according to claim 13, wherein the cleaning solvent of step S4) comprises water.

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