Laser photothermal transfer film

Abstract

[Problem to be solved] The objective is to provide a laser photothermal transfer film that improves transfer properties by using a bismaleimide resin with a high expansion coefficient as an adhesive. [Solution] A laser photothermal transfer film comprising, in sequence, a substrate film, a photothermal conversion layer, and an adhesive layer, wherein the aforementioned photothermal conversion layer is solid at room temperature and contains an infrared light absorber represented by general formula (1) and a bismaleimide resin represented by general formula (3) and / or general formula (4): In general formula (1), p is 1 or 2, R1 to R8 are independently substituted or unsubstituted linear or branched alkyl groups having 1 to 10 carbon atoms, and X- is a fluoroalkyl phosphate anion represented by general formula (2).

Description

Technical Field

[0001] This invention relates to a laser photothermal transfer film, which sequentially comprises a substrate film, a photothermal conversion layer and an adhesive layer, wherein the photothermal conversion layer heats up and expands when irradiated by a laser. Prior Technology

[0002] The light absorbers used in photothermal transfer films for photothermal conversion include infrared-absorbing dyes, pigments, and metallic materials. Infrared-absorbing dyes have the following advantages: on the one hand, they have the peak absorbance in the near-infrared region, which is the typical infrared laser wavelength range used in laser photothermal transfer; on the other hand, they can be widely selected as materials that exhibit relatively low absorbance in the visible light region below 700 nm.

[0003] For example, Patent Document 1 discloses Prussian blue (or Pigment Blue 27), copper phthalocyanine (Pigment Blue 15), polymethine dyes, cyanine dyes, etc., as materials suitable for use as radiation absorbers in image formation for 808 nm lasers.

[0004] On the other hand, Patent Document 2 discloses dyes of the indolium salts or benzo[e]indolium salts series as dyes applicable to specific photothermal conversion layers, wherein the maximum absorbance of the photothermal conversion layer at wavelengths of 650-1200 nm is more than three times greater than the maximum absorbance of the photothermal conversion layer at wavelengths of 400-650 nm. Examples of benzo[e]indolium salts are shown below.

[0005] Patent document 3 discloses a metal complex of phthalocyanine compounds as a light absorber for laser photothermal transfer. An example of a phthalocyanine-metal complex is shown below. However, because the transmittance in the visible light region is insufficient when using the aforementioned dye, problems arise in the quality inspection of the resulting transfer film and its placement alongside receiver elements. M represents several hydrogen atoms, a divalent metal, a trivalent metal derivative, or a tetravalent metal derivative; R1 to R8 represent alkyl or alkoxyalkyl groups, respectively; X1 to X8 represent sulfur or NR9, respectively; X1 = (any one of X3 or X4) = (any one of X5 or X6) = (any one of X7 or X8) = sulfur; X2 = (the other one of X3 and X4) = (the other one of X5 and X6) = (the other one's X7 and X8) = NR9; R9 represents hydrogen or alkyl; however, the above R1, etc., only apply to the above formulas.

[0006] Patent document 4 discloses a photothermal transfer film composed of a photothermal conversion layer and an adhesive layer. In this patent, after irradiation with an infrared laser, the photothermal conversion layer expands, thereby transferring the transfer material to a specific location. Examples of the adhesive include acrylic resins (such as polyacrylates, polymethacrylates, polyacrylic acid, or copolymers of these with olefins; these may or may not have hydrophilic functional groups such as -OH or -COOH). These resins have low transfer capabilities due to insufficient heat resistance and a low coefficient of thermal expansion. [Previous Technical Documents] (Patent Documents)

[0007] Patent Document 1: Korean Publication No. 2009-0034364 Patent Document 2: Korean Publication No. 2007-0067725 Patent Document 3: U.S. Patent No. 6,066,729 Patent Document 4: Korean Publication No. 2019-0106498 Summary of the Invention

[0008] [The problem the invention aims to solve] The present invention was developed in view of the above reasons, and aims to provide a laser photothermal transfer film, which improves the transfer characteristics by using a bismaleimide resin with a high expansion rate as an adhesive for the photothermal transfer layer, and the photothermal transfer layer expands significantly after laser irradiation. [Technical means to solve the problem]

[0009] To address the aforementioned problems, this invention provides a laser photothermal transfer film, characterized by the sequential deposition of three layers: a substrate film, a photothermal conversion layer, and an adhesive layer. Furthermore, the aforementioned photothermal conversion layer is solid at room temperature and contains an infrared light absorber represented by general formula (1) and a bismaleimide resin represented by general formula (3) and / or general formula (4). In general formula (1), p is 1 or 2, R1 to R8 are independently substituted or unsubstituted linear or branched alkyl groups having 1 to 10 carbon atoms, and may be substituted by cyano, nitro, carboxyl, sulfonic acid, halogen atom, hydroxyl, alkoxy, alkoxyalkoxy, acetoxy, or alkylamine groups having 1 to 8 carbon atoms, and X- is a fluoroalkyl phosphate anion represented by the following general formula (2); In general formula (2), x is 0 or 1, y is 1, 2 or 3, z is 6-y, and R9~R13 are hydrogen or fluorine, respectively. In general formula (3), A represents a tetravalent organogroup containing an aromatic or aliphatic ring; Q represents a straight-chain extended alkyl group with 6 or more carbon atoms; R independently represents a straight-chain or branched alkyl group with 6 or more carbon atoms; n represents an integer from 1 to 10; In general formula (4), A' represents a tetravalent organic group containing an aromatic ring or an aliphatic ring; B is an alkyl chain with 6 to 18 carbon atoms that has a divalent aliphatic ring containing heteroatoms; Q' represents a straight-chain alkyl chain with 6 or more carbon atoms; R' independently represents a straight-chain or branched alkyl group with 6 or more carbon atoms; n' represents an integer from 1 to 10; m represents an integer from 1 to 10.

[0010] If such a laser photothermal transfer film is to be provided, then a laser photothermal transfer film with improved transfer characteristics can be provided.

[0011] Furthermore, it is preferred in this invention that the adhesive used to form the aforementioned adhesive layer is one or a combination of two or more selected from polyacrylate, polymethacrylate, epoxy, polystyrene, polyurethane, polyurethane, polyester, polyimide and silicone resin.

[0012] The adhesive for laser photothermal transfer films is preferably such an adhesive.

[0013] Furthermore, it is preferred in this invention that the content of the aforementioned infrared light absorber contained in the aforementioned photothermal conversion layer is 1 to 15% by mass, and the content of the bismaleimide resin is 85 to 99% by mass.

[0014] If it is such a laser photothermal transfer film, the infrared light absorber can be properly dispersed in the adhesive resin, and sufficient heat can be generated by irradiating with laser light.

[0015] Furthermore, it is preferred in this invention that the thickness of the aforementioned adhesive layer is 1~10 μm.

[0016] If it is such a laser photothermal transfer film, the adhesion is sufficient, the transfer body will adhere well, and the transfer characteristics are easy to control after laser irradiation.

[0017] Furthermore, it is preferred in this invention that the thickness of the aforementioned photothermal conversion layer is 0.1~20 μm.

[0018] If it is such a laser photothermal transfer film, the photothermal conversion layer will locally absorb heat and expand due to laser irradiation, thus making it easy to transfer.

[0019] Furthermore, it is preferred in this invention that the maximum absorption wavelength of the aforementioned infrared light absorber is in the range of 780~1500 nm.

[0020] If it is such a laser photothermal transfer film, then the photothermal conversion efficiency is high by using near-infrared light.

[0021] Furthermore, it is preferred in this invention that the adhesive force of the aforementioned adhesive layer is 0.1~10 N / 25 mm.

[0022] If it is such a laser photothermal transfer film, the transfer material can be well transferred to the transfer substrate by irradiating with a laser.

[0023] Furthermore, it is preferred in this invention that the aforementioned substrate film is a transparent thermoplastic resin.

[0024] If the substrate film is such, laser light can be irradiated from the substrate film side to cause the photothermal conversion layer to expand.

[0025] Furthermore, it is preferred in this invention that the thermal decomposition start temperature of the aforementioned bismaleimide resin curing product is 300°C or higher and the glass transition temperature is 150°C or lower, and the coefficient of thermal expansion above the glass transition temperature is 100 ppm / °C or higher.

[0026] If it is such a laser photothermal transfer film, it is possible to transfer from the laser photothermal transfer film to the transfer substrate with good precision. [effect]

[0027] As described above, the present invention provides a laser photothermal transfer film in which a bismaleimide resin with a high expansion coefficient is used as an adhesive for the photothermal conversion layer. After laser irradiation, the photothermal conversion layer expands significantly, reducing the adhesion area between the transfer body and the adhesive layer and adjusting the adhesion force to a specific range, thereby improving the transfer characteristics. Therefore, it is highly suitable as a laser photothermal transfer film. Simple Explanation of the Diagram

[0028] Figure 1 is a schematic cross-sectional view showing an example of the laser photothermal transfer film of the present invention. Figure 2 is a schematic diagram showing an example of an assembly process for transferring components using the laser photothermal transfer film of the present invention. Figure 3 is a schematic diagram showing an example of measuring the expansion of the laser photothermal transfer film of the present invention in 3D using a laser irradiation method and photographed using a KEYENCE VHX digital microscope. Implementation

[0029] After conducting research to solve the aforementioned problems, the inventors discovered a laser photothermal transfer film that can solve the aforementioned problems and thus completed the present invention. The laser photothermal transfer film consists of three layers in sequence: a substrate film, a photothermal conversion layer, and an adhesive layer. The photothermal conversion layer contains an infrared light absorber represented by the following general formula (1) and a bismaleimide resin represented by the following general formula (3) and / or the following general formula (4).

[0030] In other words, the present invention is a laser photothermal transfer film, characterized in that: a substrate film, a photothermal conversion layer, and an adhesive layer are sequentially laminated, and the aforementioned photothermal conversion layer is solid at room temperature and contains an infrared light absorber represented by general formula (1) and a bismaleimide resin represented by the following general formula (3) and / or general formula (4): In general formula (1), p is 1 or 2, R1 to R8 are independently substituted or unsubstituted linear or branched alkyl groups having 1 to 10 carbon atoms, and may be substituted by cyano, nitro, carboxyl, sulfonic acid, halogen atom, hydroxyl, alkoxy, alkoxyalkoxy, acetoxy, or alkylamine groups having 1 to 8 carbon atoms, and X- is a fluoroalkyl phosphate anion represented by the following general formula (2); In general formula (2), x is 0 or 1, y is 1, 2 or 3, z is 6-y, and R9~R13 are hydrogen or fluorine, respectively. In general formula (3), A represents a tetravalent organogroup containing an aromatic or aliphatic ring; Q represents a straight-chain extended alkyl group with 6 or more carbon atoms; R independently represents a straight-chain or branched alkyl group with 6 or more carbon atoms; n represents an integer from 1 to 10; In general formula (4), A' represents a tetravalent organic group containing an aromatic ring or an aliphatic ring; B is an alkyl chain with 6 to 18 carbon atoms that has a divalent aliphatic ring containing heteroatoms; Q' represents a straight-chain alkyl chain with 6 or more carbon atoms; R' independently represents a straight-chain or branched alkyl group with 6 or more carbon atoms; n' represents an integer from 1 to 10; m represents an integer from 1 to 10.

[0031] As described above, the present invention relates to a laser photothermal transfer film, and specifically to a laser photothermal transfer film in which a photothermal conversion layer and an adhesive layer are deposited on a substrate film. The photothermal conversion layer contains an infrared light absorber of a diammonium salt series dye and a bismaleimide resin with a high coefficient of thermal expansion, and the transfer characteristics are improved by means of: high transmittance in the visible light region and an adhesive layer having an appropriate and correct range of adhesion.

[0032] The photothermal conversion layer is a thin layer formed by thermosetting an infrared light absorber containing a diammonium salt series dye with a large coefficient of thermal expansion. The thickness of the adhesive layer is set to a specific range to adjust the adhesion. After laser irradiation, the photothermal conversion layer and the adhesive layer will expand and deform. As the ground plane of the semiconductor device is reduced, the adhesion is reduced, and the semiconductor device can be transferred to a specific substrate.

[0033] The present invention will be described in detail below, but the present invention is not limited thereto.

[0034] Laser photothermal transfer film This invention relates to a laser photothermal transfer film, which comprises three layers in sequence: a substrate film, a photothermal conversion layer, and an adhesive layer. The aforementioned photothermal conversion layer is solid at room temperature and contains a specific infrared light absorber and a specific bismaleimide resin. Furthermore, in this invention, room temperature refers to 25°C.

[0035] As shown in Figure 1, the laser photothermal transfer film 1 of the present invention is formed by sequentially stacking three layers: a substrate film 11, a photothermal conversion layer 12, and an adhesive layer 13. The photothermal conversion layer 12 contains a specific infrared light absorber and a specific bismaleimide resin. When laser light is irradiated onto the laser photothermal transfer film 1, the photothermal conversion layer 12 heats up and expands, thus pushing the adhesive layer 13 above it upwards and causing it to bulge. The following describes each layer.

[0036] <Substrate Film> The substrate film acts as a substrate, which supports the photothermal conversion layer, adhesive layer, and transfer body, etc. The transfer body is attached to the adhesive layer.

[0037] The substrate film can be a polymer film. Suitable materials for use as the substrate film include, for example, polycarbonate, polyolefin, polyethylene resin, or polyester. The substrate film is preferably a transparent thermoplastic resin. Polyester films that balance light transmittance and thermal stability can be used, such as polyethylene terephthalate or polyethylene naphthalate films, but are not limited to these. Films with sufficient mechanical and thermal stability, and optical properties such as high transmittance of light of specific wavelengths can be used.

[0038] The thickness of the aforementioned substrate film is preferably 10-250 μm. It can undergo primer treatment and roughening treatment to improve adhesion to the photothermal conversion layer, and can be subjected to stretching or heat treatment for thermal stability and water-repellent treatment. Furthermore, it can contain a small amount of microparticles or filler materials to adjust light transmittance. Specifically, to enable laser light transmission, the substrate film is preferably a 50-200 μm biaxially stretched polyethylene terephthalate (PET) film with a visible light transmittance of approximately 90% or more.

[0039] <Photothermal conversion layer> The photothermal conversion layer is solid at room temperature and contains an infrared light absorber represented by general formula (1) and a bismaleimide resin represented by general formula (3) and / or general formula (4). The photothermal conversion layer absorbs light (laser) and converts it into heat by one or more infrared light absorbers contained therein. The photothermal conversion layer expands, thereby transferring the semiconductor device to the transfer substrate by the physical force caused by the thermal expansion.

[0040] The infrared light absorber contained in the photothermal conversion layer is preferably 1-15% by mass, and the bismaleimide resin is preferably 85-99% by mass.

[0041] The photothermal conversion layer expands locally due to heat absorption when irradiated by a laser. Therefore, since the photothermal conversion layer is easy to transfer, it is preferable to make it as thin as possible, preferably with a thickness of 0.1 to 20 μm.

[0042] The infrared light absorber used in the photothermal conversion layer of the photothermal transfer film of the present invention is a diimonium salt series dye represented by the following general formula (1).

[0043] In general formula (1), p is 1 or 2, R1 to R8 are independently substituted or unsubstituted linear or branched alkyl groups having 1 to 10 carbon atoms, and may be substituted by cyano, nitro, carboxyl, sulfonic acid, halogen atom, hydroxyl, alkoxy, alkoxyalkoxy, acetoxy, or alkylamine groups having 1 to 8 carbon atoms, and X- is a fluoroalkyl phosphate anion represented by the following general formula (2); In general formula (2), x is 0 or 1, y is 1, 2 or 3, z is 6-y, and R9~R13 are hydrogen or fluorine, respectively.

[0044] In this invention, when a polyethylene terephthalate (PET) film with a thickness of, for example, 100 μm is used as the substrate film, the visible light transmittance of the biaxially stretched PET film can be set to approximately 90%. When the infrared light absorber represented by the above general formula (1) is used in this substrate film, a photothermal transfer film can be manufactured that maintains transfer performance and has a visible light transmittance of 60% or more.

[0045] Visible light transmittance is inversely proportional to the concentration of the infrared light absorber used in the photothermal conversion layer. The diammonium salt series organic dyes used as the infrared light absorber in this invention have superior absorbance in the near-infrared region, specifically in the 780-1500 nm wavelength range, compared to other organic dyes, thus resulting in high efficiency of photothermal conversion via near-infrared radiation. On the other hand, they exhibit increased absorbance in the visible light region and high transparency in the visible light region. In other words, it is preferable that the maximum absorption wavelength of the infrared light absorber is in the range of 780-1500 nm.

[0046] To adjust the adhesion between the dye and the substrate film and / or adhesive layer, the aforementioned infrared light absorber, namely the diammonium salt series dye, is used in conjunction with the adhesive. Because the diammonium salt series dye has excellent solubility in organic solvents, it can be uniformly dispersed in the bismaleimide resin that serves as the adhesive. As a result, since it is uniformly dispersed within the resin, the heat generated by the laser through spot irradiation becomes more uniform. Furthermore, this good dispersibility has the advantage of reducing thickness deviations in photothermal conversion layers with a thickness of less than 10 μm.

[0047] The bismaleimide resin used as the adhesive in the photothermal conversion layer is a solid bismaleimide resin at 25°C, and is a maleimide compound having at least one dimeric acid backbone, at least one straight-chain extended alkyl group with 6 or more carbon atoms, and at least two maleimide groups in its molecule. Because it has a straight-chain extended alkyl group with 6 or more carbon atoms, it exhibits excellent heat resistance and a large coefficient of thermal expansion, thus expanding significantly due to the heat generated from absorbing laser light, making transfer printing easy. In this invention, such a bismaleimide resin is a bismaleimide resin represented by the following general formula (3) and / or general formula (4).

[0048] In general formula (3), A represents a tetravalent organogroup containing an aromatic or aliphatic ring; Q represents a straight-chain extended alkyl group with 6 or more carbon atoms; R independently represents a straight-chain or branched alkyl group with 6 or more carbon atoms; n represents an integer from 1 to 10; In general formula (4), A' represents a tetravalent organic group containing an aromatic ring or an aliphatic ring; B is an alkyl chain with 6 to 18 carbon atoms that has a divalent aliphatic ring containing heteroatoms; Q' represents a straight-chain alkyl chain with 6 or more carbon atoms; R' independently represents a straight-chain or branched alkyl group with 6 or more carbon atoms; n' represents an integer from 1 to 10; m represents an integer from 1 to 10.

[0049] In general formula (3), Q and in general formula (4), Q' are straight-chain extended alkyl groups, which have 6 or more carbon atoms, preferably 6 or more and 20 or less, and more preferably 7 or more and 15 or more. In addition, in general formula (3), R and in general formula (4), R' have 6 or more carbon atoms, preferably 6 or more and 12 or less, and R and R' can be, for example, straight-chain or branched alkyl groups.

[0050] In general formula (3), A and in general formula (4), A' represents a tetravalent organic group containing an aromatic ring or an aliphatic ring, preferably any one of the tetravalent organic groups represented by the following structural formulas. Furthermore, the unsubstituented bonds in the above structural formulas are bonded to the carbonyl carbon used to form the cyclic amide structure in general formulas (3) and (4).

[0051] Furthermore, B in general formula (4) is an alkyl chain with 6 to 18 carbon atoms having a divalent aliphatic ring that may contain heteroatoms, preferably with 8 or more and 15 or less carbon atoms. B in general formula (4) is preferably any one of the alkyl chains having an aliphatic ring represented by the following structural formulas. Furthermore, the unsubstituented bonds in the above structural formula are bonded to the nitrogen atom used to form the cyclic amide structure in general formula (4).

[0052] In general formula (3), n is an integer from 1 to 10, preferably an integer from 2 to 7. In general formula (4), n' is an integer from 1 to 10, preferably an integer from 2 to 7. In general formula (4), m is an integer from 1 to 10, preferably an integer from 2 to 7.

[0053] The weight-average molecular weight (Mw) of the bismaleimide resin is not particularly limited as long as it is solid at room temperature. Preferably, it is 2,000 to 50,000, more preferably 2,500 to 40,000, and even more preferably 3,000 to 20,000, obtained by gel permeation chromatography (GPC) using polystyrene standards. If the molecular weight is above 2,000, the bismaleimide resin is solidified at room temperature. If the molecular weight is below 50,000, there is no concern about excessively high viscosity leading to reduced flowability in the coating composition described later, and the molding properties are good. Furthermore, the Mw mentioned in this specification refers to the weight-average molecular weight measured by GPC using polystyrene as a standard substance under the following conditions.

[0054] <Measurement Conditions> Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.35 mL / min Detector: Differential Refractive Index Detector (RI) Column:TSK Guardcolumn SuperH-L TSKgel SuperHZ4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ2000(4.6mmI.D.×15cm×2) (All were under the Dongcao Company system) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass THF solution)

[0055] The bismaleimide resins that can be used in this invention are preferably commercially available SLK3000, SLK689, SLK2600, etc., which are part of the SLK series (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0056] A coating composition, which has become a varnish-like solution, can be prepared by dissolving and dispersing the aforementioned infrared absorber, binder (i.e., bismaleimide resin), and hardening catalyst in an organic solvent such as anisole. This varnish-like solution is coated onto a substrate film and deposited. After coating, heat is applied in a heating bath to remove the solvent, causing the bismaleimide resin to dry and solidify, thus forming a photothermal conversion layer on the substrate film. This photothermal conversion layer is solid at room temperature and contains the infrared absorber and maleimide resin.

[0057] The photothermal conversion layer only needs to be solid at room temperature (25°C), and a curing catalyst can be added as needed. The curing catalyst can be imidazole-based catalysts, organic peroxides, etc., as long as it is a catalyst that reacts with maleimine groups, there are no particular limitations.

[0058] The solids content of the coating composition is preferably 5-85% by mass, more preferably in the range of 5-60% by mass. If the solids content of the above composition is 5% by mass or more, it is easy to process to the desired coating thickness. If it is 85% by mass or less, the viscosity of the coating resin will not increase, and the surface will not be rough after coating, which is more suitable.

[0059] Furthermore, in the solid component of the above-mentioned composition, the content of infrared light absorber (diammonium salt series dye) is preferably 1 to 15% by mass. If the content of infrared light absorber is 1% by mass or more, sufficient heat generation will be generated; if it is 15% by mass or less, the solubility of infrared light absorber will not decrease, and it will be properly dispersed in the adhesive resin.

[0060] Since the resin is heated by the heat generated by the laser irradiation, the thermal decomposition start temperature of the cured bismaleimide resin is preferably above 300°C, more preferably above 400°C, and the glass transition temperature is preferably below 150°C, more preferably below 100°C, and even more preferably below 50°C.

[0061] The coefficient of thermal expansion of the cured bismaleimide resin is preferably below 100 ppm / ℃ below the glass transition temperature, and preferably above 100 ppm / ℃ above the glass transition temperature, and more preferably above 150 ppm / ℃.

[0062] Generally, heat-resistant polyimide resins with a thermal decomposition start temperature of 300°C or higher have a glass transfer temperature of 200°C or higher, and a coefficient of thermal expansion of 20 ppm / °C or lower below the glass transfer temperature and 80 ppm / °C or lower above the glass transfer temperature. Therefore, the expansion of the photothermal transfer layer of the polyimide resin after laser irradiation is smaller than that of the bismaleimide resin used in this invention, making it difficult to accurately transfer the photothermal transfer film from the laser photothermal transfer film to the transfer substrate. Therefore, it is necessary to bring the transfer substrate, to which semiconductor elements will be transferred, as close as possible to the laser photothermal transfer film beforehand. Consequently, it is difficult to control the transfer force from the laser photothermal transfer film.

[0063] When using the laser photothermal transfer film of the present invention, it expands significantly due to laser irradiation, thus enabling the transfer substrate and the laser photothermal transfer film to be disposed separately. Furthermore, since the front end area of ​​the photothermal conversion layer, which has expanded into a convex shape due to heat, is reduced, the adhesion is further reduced, making it easier to transfer semiconductor devices to the transfer substrate.

[0064] The above coating composition may further contain: crosslinking agent, humectant, surfactant, pH adjuster, viscosity adjuster, and cosolvent, etc.

[0065] Lasers used for photothermal conversion include, for example, infrared lasers, visible light lasers, UV lasers, and excimer lasers, among which infrared lasers are preferred.

[0066] <Adhesive layer> The adhesive layer enables the semiconductor device to adhere to the laser photothermal transfer film. The adhesive strength of this layer is designed with the adhesion to the transfer substrate in mind. This ensures that the adhesion of both the laser photothermal transfer film and the transfer substrate is appropriate, avoiding problems such as the transfer body gradually shifting to the transfer substrate side during film bonding, and preventing transfer to the transfer substrate. The adhesion of the laser transfer film is preferably 0.1 to 10 N / 25 mm in the 180° peel test (attached to SUS (stainless steel)) according to JIS Z 0237, and can be adjusted within this range according to the adhesion to the transfer substrate side.

[0067] The thickness of the adhesive layer is preferably 1 to 10 μm. When the thickness of the adhesive layer is 1 μm or more, the adhesion will not decrease and the transfer material will adhere well. If the thickness is less than 10 μm, the transfer characteristics can be easily controlled after laser irradiation.

[0068] The adhesive layer is preferably one or a combination of two or more selected from polyacrylate, polymethacrylate, epoxy, polystyrene, polyurethane, polyurethane, polyester, polyimide and silicone resin.

[0069] Among these, silicone adhesives with excellent heat resistance and stain resistance are preferred. Silicone adhesives are particularly suitable materials because the adhesive layer transfers less to the semiconductor device and exhibits excellent thermal stability. Examples of silicone adhesives include platinum addition-curing and condensation-curing types with MQ resin and high-viscosity vinyl siloxane as the main components; platinum addition-curing types, which cure rapidly after being coated on the surface of the photothermal conversion layer, are preferred.

[0070] The aforementioned silica adhesive can be diluted with solvents such as toluene, and after coating the photothermal conversion layer with a thickness of 1-10 μm using a thin film coater and a smearer, the solvent is dried and the adhesive is hardened.

[0071] The transfer substrate for laser photothermal transfer film transfer is not particularly limited to any solid-shaped object such as a semiconductor element, a light-emitting element such as an LED (light-emitting diode), a ceramic substrate, a plastic or ceramic package encapsulating a semiconductor element or LED element, a ceramic substrate or resin sheet containing phosphors, or a multilayer capacitor. In particular, transferring micron-sized LEDs and mini-sized LEDs onto a transfer substrate that has solder bumps and an anisotropic conductive layer to become a display substrate enables the fabrication of LED-based display devices.

[0072] <Transfer Process> Figure 2 shows an example of the mounting process for transferring components using the laser photothermal transfer film 1 of the present invention. The laser photothermal transfer film 1 has an adhesion release layer 14 deposited on the substrate film 11. The adhesion release layer 14 is formed by sequentially depositing the photothermal conversion layer 12 and the adhesive layer 13 from the side of the substrate film 11. On the other hand, solder 16 has been applied to the part where the component is to be transferred on one surface of the transfer substrate 15 by printing or the like. After attaching the component 17 to the adhesive layer surface of the release layer 14 of the laser photothermal transfer film 1, with the component 17 facing the solder 16, and setting the distance (gap 18) between the laser photothermal transfer film 1 and the transfer substrate 15, it is placed in a laser irradiation apparatus. Then, laser light is irradiated from the substrate film 11 side, causing the photothermal conversion layer to expand 19. At this time, the photothermal conversion layer 12 pushes the adhesive layer 13 above it upward and bulges, and the component 17 is transferred to the solder 16 on the transfer substrate 15. [Example]

[0073] The following examples and comparative examples will be used to describe the structure of the present invention and its accompanying effects in more detail. However, these examples are used to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

[0074] The physical properties of the bismaleimide resin used in the examples / comparative examples are shown in Table 1.

[0075] [Table 1] SLK3000 SLK689 SLK2600 Polyimide Glass transition temperature 80℃ 30℃ 150℃ 230℃ Thermal decomposition start temperature Above 400℃ Above 400℃ Above 400℃ 350℃ coefficient of thermal expansion 150 ppm / ℃ 170 ppm / ℃ 150 ppm / ℃ 80 ppm / ℃ (Tg and above)

[0076] <Example 1> (1) Substrate film: TORAY Corporation's optical PET film (100 μm thick) is used as the substrate film. (2) Composition for photothermal conversion layer: The composition for photothermal conversion layer (coating composition) is prepared by dissolving the amounts of diammonium salt series dye (manufactured by Nippon Kayaku Co., Ltd., KAYASORB IRG-069), bismaleimide resin (SLK3000), and peroxide (dicumyl peroxide) as a curing catalyst in anisole. (3) Adhesive layer: The adhesive layer used for the attachment of the transfer body is prepared by mixing KR-3704 (manufactured by Shin-Etsu Chemical Co., Ltd.) and X-40-3237-1 (manufactured by Shin-Etsu Chemical Co., Ltd.) at a ratio of 75:25 (mass ratio) and further adding 0.5% of CAT PL-50T manufactured by Shin-Etsu Chemical Co., Ltd. to prepare an adhesive with a solid content of 35% by mass.

[0077] Manufacturing of Laser Photothermal Transfer Film The photothermal transfer layer composition was applied to the substrate film using a Mayer bar and dried and cured at 150°C for 2 hours to form a photothermal transfer layer with an average thickness of 2.5 μm. Then, an adhesive was applied using a smearer and dried at 100°C for 3 minutes to form an adhesive layer with an average thickness of 3 μm (adhesion was 0.3 N / 25 mm in the 180° peel test (SUS substrate) according to JIS Z 0237). After fabricating the laser photothermal transfer film (Figure 1), the transfer characteristics were evaluated using the methods described below. The results are shown in Table 3.

[0078] <Example 2> The amount of diammonium salt was varied, and the amount of peroxide (dicumene peroxide) used as a curing catalyst, as recorded in Table 2, was dissolved in anisole to prepare the composition for the photothermal conversion layer. Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0079] <Example 3> The amount of diammonium salt was varied, and the amount of peroxide (dicumene peroxide) used as a curing catalyst, as recorded in Table 2, was dissolved in anisole to prepare the composition for the photothermal conversion layer. Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0080] <Example 4> The bismaleimide resin was changed to SLK689 and SLK2600, and the peroxide (dicumene peroxide) used as a curing catalyst in the amount listed in Table 2 was dissolved in anisole to prepare the composition for the photothermal conversion layer. Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0081] <Example 5> The amount of diammonium salt was varied, and the amount recorded in Table 2 was dissolved in anisole without the addition of peroxide (dicumene peroxide) to prepare the composition for the photothermal conversion layer. Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0082] <Example 6> The amount of diammonium salt was varied, and the amount of peroxide (dicumene peroxide) used as a curing catalyst, as recorded in Table 2, was dissolved in anisole to prepare the composition for the photothermal conversion layer. Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0083] <Example 7> The amount of diammonium salt was varied, and the amount of peroxide (dicumene peroxide) used as a curing catalyst, as recorded in Table 2, was dissolved in anisole to prepare the composition for the photothermal conversion layer. Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0084] <Comparative Example 1> The bismaleimide resin was replaced with a polyimide resin, and the composition for the photothermal transfer layer was prepared by dissolving the amount listed in Table 2 in NMP (N-methylpyrrolidone). Otherwise, the process was the same as in Example 1 to manufacture a laser photothermal transfer film and evaluate the transfer characteristics. The results are shown in Table 3.

[0085] <Evaluation of Transfer Properties> A transfer substrate was fabricated by applying solder paste to predetermined electrodes on a PCB (printed circuit board) substrate using screen printing to a thickness of 20 μm. Meanwhile, 100 evaluation optoelectronic semiconductor elements (500 μm square) were attached to a laser photothermal transfer film consisting of a substrate, a photothermal conversion layer, and an adhesive layer, prepared in the above-described embodiments and comparative examples. The distance between the laser photothermal transfer film and the transfer substrate was set to 150 μm, and the film was placed in a laser irradiation apparatus. The substrate side of the laser photothermal transfer film was irradiated with laser light using an Nd:YAG 1064 nm laser device at an energy of 100 W. The optoelectronic semiconductor elements were transferred to the solder paste on the transfer substrate by the expansion of the photothermal conversion layer. The number of optoelectronic semiconductor elements transferred to the transfer substrate was measured, and the transfer characteristics were evaluated.

[0086] <Example 8> The expansion of the laser photothermal transfer film of Example 1 after laser irradiation was captured using a KEYENCE VHX digital microscope. This photograph is shown in Figure 3. In this invention, because the photothermal conversion layer contains a specific bismaleimide resin, such a high bulge can be obtained. After measuring the expansion following laser irradiation in 3D, the resulting height was 200 μm.

[0087] [Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Dimaleimide resin SLK3000 100 100 100 - 100 100 100 - SLK689 - - - 30 - - - - SLK2600 - - - 70 - - - - Polyimide - - - - - - - 100 Diammonium salt KAYASORB IRG 069 4 2 8 4 15 0.5 20 2 peroxide Dicumeneyl peroxide 1 1 1 1 - 1 1 - solvent aniline 70 70 70 70 70 70 70 - NMP - - - - - - - 70

[0088] [Table 3] Photothermal conversion layer Infrared light absorber content (quality%) Thickness of adhesive layer (μm) Transfer characteristics (%) After laser irradiation height [Average 5 points] (μm) Example 1 3.8 3 100 200 Example 2 1.9 3 100 200 Example 3 7.3 3 100 200 Example 4 3.8 3 100 200 Example 5 13 3 100 200 Example 6 0.5 3 70 150 Example 7 16.5 3 80 160 Comparative Example 1 3.8 3 40 50

[0089] As the resin contained in the composition of the photothermal transfer layer, the laser photothermal transfer films of Examples 1-7 used bismaleimide resin, while the laser photothermal transfer film of Comparative Example 1 used polyimide resin. The transfer characteristics of the laser photothermal transfer films of Examples 1-7 were superior to those of the laser photothermal transfer film of Comparative Example 1. Therefore, using bismaleimide resin with a high expansion coefficient as an adhesive in the photothermal transfer layer provides a laser photothermal transfer film with improved transfer characteristics.

[0090] 1: Laser photothermal transfer film 11: Substrate film 12: Photothermal conversion layer 13: Adhesive layer 14: Then release the layer 15: Transfer substrate 16: Solder 17: Components 18: Gap 19: Expansion of the photothermal conversion layer

[0091] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A laser photothermal transfer film, characterized in that: it is sequentially laminated with a substrate film, a photothermal conversion layer, and an adhesive layer, wherein the aforementioned photothermal conversion layer is solid at room temperature and contains an infrared light absorber represented by general formula (1) and a bismaleimide resin represented by general formula (3) and / or general formula (4): In general formula (1), p is 1 or 2, R1 to R8 are independently substituted or unsubstituted linear or branched alkyl groups having carbon numbers of 1 to 10, and may be substituted by cyano, nitro, carboxyl, sulfonic acid, halogen atom, hydroxyl, alkoxy group having carbon numbers of 1 to 8, alkoxyalkoxy group having carbon numbers of 1 to 8, acetoxy group having carbon numbers of 1 to 8, or alkylamine group having carbon numbers of 1 to 8, and X- is a fluoroalkyl phosphate anion represented by general formula (2). In general formula (2), x is 0 or 1, y is 1, 2 or 3, z is 6-y, and R9 to R13 are hydrogen or fluorine, respectively. In general formula (3), A represents a tetravalent organic group containing an aromatic ring or an aliphatic ring; Q represents a straight-chain extended alkyl group with 6 or more carbon atoms; R represents a straight-chain or branched alkyl group with 6 or more carbon atoms, respectively; n represents an integer from 1 to 10. In general formula (4), A' represents a tetravalent organic group containing an aromatic ring or an aliphatic ring; B is an extended alkyl chain with 6 to 18 carbon atoms that has a divalent aliphatic ring and may contain heteroatoms; Q' represents a straight-chain extended alkyl group with 6 or more carbon atoms; R' represents a straight-chain or branched alkyl group with 6 or more carbon atoms, respectively; n' represents an integer from 1 to 10; m represents an integer from 1 to 10.

2. The laser photothermal transfer film as described in claim 1, wherein, The adhesive used to form the aforementioned adhesive layer is one or a combination of two or more selected from polyacrylate, polymethacrylate, epoxy resin, polystyrene, polyurethane, polyurethane, polyester, polyimide and silicone resin.

3. The laser photothermal transfer film as described in claim 1, wherein, The aforementioned infrared light absorber contained in the aforementioned photothermal conversion layer is 1-15% by mass, and the bismaleimide resin is 85-99% by mass.

4. The laser photothermal transfer film as described in claim 2, wherein, The aforementioned infrared light absorber contained in the aforementioned photothermal conversion layer is 1-15% by mass, and the bismaleimide resin is 85-99% by mass.

5. The laser photothermal transfer film as claimed in claim 1, wherein, The thickness of the aforementioned adhesive layer is 1–10 μm.

6. The laser photothermal transfer film as claimed in claim 2, wherein, The thickness of the aforementioned adhesive layer is 1–10 μm.

7. The laser photothermal transfer film as described in claim 3, wherein, The thickness of the aforementioned adhesive layer is 1–10 μm.

8. The laser photothermal transfer film as claimed in claim 4, wherein, The thickness of the aforementioned adhesive layer is 1–10 μm.

9. The laser photothermal transfer film as claimed in claim 1, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

10. The laser photothermal transfer film as claimed in claim 2, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

11. The laser photothermal transfer film as claimed in claim 3, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

12. The laser photothermal transfer film as claimed in claim 4, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

13. The laser photothermal transfer film as claimed in claim 5, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

14. The laser photothermal transfer film as claimed in claim 6, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

15. The laser photothermal transfer film as claimed in claim 7, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

16. The laser photothermal transfer film as claimed in claim 8, wherein, The thickness of the aforementioned photothermal conversion layer is 0.1–20 μm.

17. The laser photothermal transfer film as claimed in any one of claims 1 to 16, wherein, The maximum absorption wavelength of the aforementioned infrared light absorber is in the range of 780–1500 nm.

18. The laser photothermal transfer film as claimed in any one of claims 1 to 16, wherein, The adhesion of the aforementioned adhesive layer is 0.1 to 10 N / 25 mm.

19. The laser photothermal transfer film as claimed in any one of claims 1 to 16, wherein, The aforementioned substrate film is a transparent thermoplastic resin.

20. The laser photothermal transfer film as claimed in any one of claims 1 to 16, wherein, The thermal decomposition start temperature of the aforementioned bismaleimide resin curing product is above 300°C and the glass transition temperature is below 150°C, and the coefficient of thermal expansion above the glass transition temperature is above 100 ppm / °C.

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