Anisotropic conductive film

Abstract

To provide an anisotropic conductive film that offers excellent resistance to high light energy. [Solution] The anisotropic conductive film comprises a fluororesin and solder particles 11 dispersed in the fluororesin. Furthermore, a first film 13 is attached to the first surface of the anisotropic conductive film as needed, and a second film 14 is attached to the second surface. When heated, the fluororesin melts, and the solder particles 11 are melted while sandwiched between electrodes, thus forming a bond. This provides excellent resistance to high light energy.

Description

【Technical Field】 【0001】 The present invention relates to an anisotropic conductive film for mounting chips (elements) such as LEDs (Light Emitting Diodes). 【Background Art】 【0002】 For high-pressure mercury lamps for general lighting, manufacturing, importing, and exporting will be prohibited in Japan after December 31, 2020. Although lamps for special applications other than general lighting, such as ultraviolet lamps, are not subject to regulation, LEDs that emit ultraviolet light have been developed as an alternative technology to ultraviolet lamps. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2010-024301 【Patent Document 2】 Japanese Patent Application Laid-Open No. 2012-186322 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 Conventionally, wire bond bonding is known as a method for mounting an LED on a substrate. However, wire bond bonding has disadvantages such as the wire being easily broken, electrical connection failures may occur, and in addition, the substrate has no versatility, is difficult to miniaturize, and cannot be made flexible. 【0005】 In Patent Documents 1 and 2, a method of flip-chip mounting an LED on a substrate using an anisotropic conductive film in which conductive particles are dispersed in an epoxy-based adhesive and formed into a film has been proposed. 【0006】 However, in the technologies described in Patent Documents 1 and 2, when blue LEDs or ultraviolet LEDs are implemented, the high light energy of blue light and ultraviolet light causes resin degradation of the anisotropic conductive film, making it impossible to obtain long-term connection reliability. 【0007】 This technology was proposed in light of the conventional situation and provides an anisotropic conductive film that offers excellent resistance to high light energy. [Means for solving the problem] 【0008】 As a result of diligent research, the inventors of this invention discovered that the above-mentioned objectives could be achieved by using fluororesin, and thus completed the present invention. 【0009】 In other words, the anisotropic conductive film according to the present invention comprises a fluororesin and solder particles dispersed in the fluororesin. 【0010】 Furthermore, the connection structure according to the present invention comprises a first electronic component, a second electronic component, and an anisotropic conductive film having a fluororesin and solder particles, connecting the electrodes of the first electronic component and the electrodes of the second electronic component, wherein the electrodes of the first electronic component and the electrodes of the second electronic component are joined by the solder particles, and the fluororesin is filled between the first electronic component and the second electronic component. 【0011】 Furthermore, the method for manufacturing the connecting structure according to the present invention involves sandwiching an anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin between the electrodes of a first electronic component and a second electronic component, and connecting the electrodes of the first electronic component and the second electronic component by thermocompression bonding. 【0012】 Furthermore, the method for manufacturing the connecting structure according to the present invention involves sandwiching an anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin between the electrodes of a first electronic component and the electrodes of a second electronic component, and connecting the electrodes of the first electronic component and the electrodes of the second electronic component by a reflow oven. 【Advantages of the Invention】 【0013】 According to the present invention, since an anisotropic conductive film in which solder particles are dispersed in a fluororesin is used, excellent resistance to high light energy can be obtained. 【Brief Description of the Drawings】 【0014】 [Figure 1] FIG. 1 is a cross-sectional view schematically showing a part of an anisotropic conductive film to which the present technology is applied. [Figure 2] FIG. 2 is a cross-sectional view showing a configuration example of an LED mounting body. [Figure 3] FIG. 3 is a cross-sectional view showing a part of the temporary bonding process in the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing a part of the mounting process in the first embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing a part of the reflow process in the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing an outline of a die shear strength test. [Figure 7] FIG. 7 is a cross-sectional photograph of a connection part of an LED mounting sample at the initial stage of mounting in Comparative Example 2. [Figure 8] FIG. 8 is a cross-sectional photograph of a connection part of an LED mounting sample after a high-temperature and high-humidity continuous lighting test in Comparative Example 2. [Figure 9] FIG. 9 is a cross-sectional photograph of a connection part of an LED mounting sample after a high-temperature and high-humidity continuous lighting test in Example 11. 【Modes for Carrying Out the Invention】 【0015】 Hereinafter, embodiments of the present invention will be described in detail in the following order with reference to the drawings. 1. Anisotropic conductive film 2. Connection structure 3. Method for manufacturing the connection structure 4. Examples 【0016】 <1. Anisotropic Conductive Film> FIG. 1 is a cross-sectional view schematically showing a part of an anisotropic conductive film to which the present technology is applied. As shown in FIG. 1, the anisotropic conductive film 10 has a fluororesin and solder particles 11 dispersed in the fluororesin. Further, a first film 12 is attached to the first surface and a second film 13 is attached to the second surface of the anisotropic conductive film 10 as needed. 【0017】 The thickness of the anisotropic conductive film 10 is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less, and still more preferably 20 μm or more and 40 μm or less. 【0018】 [Fluororesin] The fluororesin is the main component of the binder of the anisotropic conductive film, and is preferably contained in the binder at 80 wt% or more, more preferably 90 wt% or more, and still more preferably 95 wt% or more. The fluororesin is thermoplastic, and since the adhesive force of the fluororesin itself is small, the adhesive strength of the anisotropic conductive film is exhibited by metal bonding with solder particles. 【0019】 Table 1 shows the values obtained by converting the binding energy of the main chemical bonds into light energy. The binding energy E (kcal / mol) was converted into light energy λ (nm) using the following formula. E = 1 / 4.2·N·h·c / λ h: Planck's constant (6.626×10 -27 erg·sec), c: speed of light (2.998×10 10 cm / sec), λ: wavelength (nm), N: Avogadro's constant (6.02×10 23 / mol) 【0020】 【Table 1】 【0021】 Calculations using the above light energy formula: E=hc / λ show that a blue LED (wavelength λ=460mm) = 2.8eV and an ultraviolet LED (wavelength λ=200~300nm) = 4.1~6.2eV, indicating that the light energy of an ultraviolet LED is approximately 2 to 3 times stronger than that of a blue LED. 【0022】 In contrast, as shown in Table 1, the CF bonds in fluororesins have higher bond energy than the CH bonds in epoxy resins, acrylic resins, etc., and the Si-O bonds in silicone resins, and theoretically can withstand ultraviolet light up to 248 nm. 【0023】 The melting point of the fluororesin is preferably lower than the melting point of the solder particles. This allows the fluororesin to melt, and the solder particles to be sandwiched between the terminals of the first electronic component and the terminals of the second electronic component, enabling a high bonding strength. 【0024】 The specific melting temperature of the fluororesin is preferably 80°C to 220°C, more preferably 90°C to 180°C, and even more preferably 100°C to 140°C. This reduces the thermal impact on electronic components during bonding. Furthermore, it prevents the fluororesin from melting due to the heat generated by, for example, the LED during use. 【0025】 Furthermore, the melt flow rate (MFR) of the fluororesin, measured in accordance with ASTM D1238 at a temperature of 265°C and a load of 5 kg, is preferably 1 g / 10 min to 50 g / 10 min, more preferably 5 g / 10 min to 40 g / 10 min, and even more preferably 10 g / 10 min to 30 g / 10 min. This makes it possible to melt the fluororesin and sandwich solder particles between the terminals of the first electronic component and the terminals of the second electronic component. 【0026】 The fluororesin is preferably a fluoroolefin copolymer having units based on fluoroolefins. Examples of fluoroolefins include tetrafluoroethylene (TFE), vinyl fluoride (VDF), vinylidene fluoride (vinylidene fluoride, VdF), trifluoroethylene, hexafluoropropylene, and chlorotrifluoroethylene (CTFE). One type of fluoroolefin may be used alone, or two or more types may be used in combination. 【0027】 Examples of fluoroolefin copolymers include polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV). Fluoroolefin copolymers may be used individually or in combination of two or more types. 【0028】 Among these fluoroolefin copolymers, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) is preferred. THV has a relatively low melting temperature and excellent flexibility compared to other fluoroolefin copolymers, making it ideal as a binder for anisotropic conductive films. Furthermore, because THV is a highly transparent resin, it exhibits excellent optical transparency and can transmit light not only in the visible light range but also in the infrared and ultraviolet ranges, making it ideal for mounting LED elements. In addition, THV can be dissolved in lower ketone solvents, ester solvents, etc., facilitating the manufacture of anisotropic conductive films. A specific example of THV available on the market is "THV221GZ" from 3M Japan Ltd. 【0029】 [Solder particles] The solder particles are dispersed in a fluororesin, and the overall arrangement of the solder particles in a plan view of the anisotropic conductive film may be regular or random. Examples of regular arrangements include grid arrangements such as square, hexagonal, orthorhombic, and rectangular grids. In the case of random arrangements, it is preferable that the solder particles do not come into contact with each other in a plan view of the film, and that the solder particles do not overlap with each other in the film thickness direction. 【0030】 The average particle size of the solder particles is preferably 10% to 100% of the film thickness, preferably 30% to 100%, and preferably 80% to 100%. A higher ratio of the average particle size of the solder particles to the film thickness tends to result in higher bonding strength. Furthermore, when reflow soldering, a higher ratio of the average particle size of the solder particles to the film thickness is preferable. If the average particle size of the solder particles is larger than the film thickness, the conductivity reliability tends to decrease. 【0031】 In this specification, the average particle diameter refers to the particle size at 50% of the integrated value in the particle size distribution determined by laser diffraction-scattering (D50). Alternatively, it may be determined by measurement with N=1000 or more using an image-type particle size distribution analyzer (for example, FPIA-3000 (Malvern Corporation)). 【0032】 Solder particles can be appropriately selected from, for example, those specified in JIS Z 3282-1999, such as Sn-Pb, Pb-Sn-Sb, Sn-Sb, Sn-Pb-Bi, Bi-Sn, Sn-Cu, Sn-Pb-Cu, Sn-In, Sn-Ag, Sn-Pb-Ag, and Pb-Ag, depending on the electrode material and connection conditions. 【0033】 The melting temperature of the solder particles is higher than the melting temperature of the fluororesin, and the difference is preferably between 10°C and 120°C, more preferably between 40°C and 120°C, and even more preferably between 80°C and 120°C. If the difference between the melting temperature of the solder particles and the melting temperature of the fluororesin is small, high bonding strength tends not to be obtained. 【0034】 The amount of solder particles is preferably 1 part by mass or more and 150 parts by mass or less per 100 parts by mass of fluororesin. If the amount of solder particles is too low, excellent conductivity, heat dissipation, and adhesion cannot be obtained, and if the amount is too high, anisotropy will be impaired and excellent conductivity reliability cannot be obtained. 【0035】 [Additives] In addition to the fluororesin and solder particles described above, various additives can be incorporated into the anisotropic conductive film, provided that they do not impair the effects of the present invention. For example, to improve temporary adhesion, it is preferable that the anisotropic conductive film further contains a tackifier. 【0036】 Examples of tackifiers that can be used include terpene resins such as terpene resins, terpene phenol resins, and hydrogenated terpene resins; rosin resins such as natural rosin, polymerized rosin, rosin esters, and hydrogenated rosin; and petroleum resins such as polybutadiene and polyisoprene. Among these, it is preferable to use a rosin resin that improves the tackiness of the anisotropic conductive film surface and functions as a flux for solder. A specific example of a rosin resin available on the market is "KE311" from Arakawa Chemical Industries, Ltd. 【0037】 The amount of tackifier added is preferably 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of fluororesin. If the amount of tackifier is too low, excellent tackiness cannot be obtained, and if the amount is too high, the fluidity of the fluororesin will be impaired, and excellent conductivity reliability cannot be obtained. 【0038】 An anisotropic conductive film with this configuration, which uses an anisotropic conductive film in which solder particles are dispersed in a fluororesin, can obtain excellent resistance to high light energy. Furthermore, because the anisotropic conductive film does not undergo reactivity such as heat curing, photocuring, or humidity curing, it has long-term storage stability. 【0039】 Furthermore, the aforementioned anisotropic conductive film can be obtained, for example, by mixing a fluororesin, solder particles, and a tackifier in a solvent, applying this mixture onto a release film using a bar coater, and then drying it to evaporate the solvent. 【0040】 <2. Connection Structure> Next, a connection structure using the anisotropic conductive film described above will be explained. The connection structure in this embodiment comprises a first electronic component, a second electronic component, a fluororesin, and solder particles, and includes an anisotropic conductive film that connects the electrodes of the first electronic component and the electrodes of the second electronic component, with the electrodes of the first electronic component and the electrodes of the second electronic component joined by the solder particles, and the fluororesin filled between the first electronic component and the second electronic component. With such a connection structure, excellent resistance to irradiation with high light energy, such as sunlight, can be obtained. 【0041】 In this embodiment, the first electronic component is preferably a chip (element) such as an LED (Light Emitting Diode) or an IC (Integrated Circuit), and the second electronic component is preferably a substrate on which the chip is mounted. 【0042】 Figure 2 is a cross-sectional view showing an example of the configuration of an LED mounting body. In this LED mounting body, the LED element 20 and the substrate 30 are connected using an anisotropic conductive film in which solder particles are dispersed in the aforementioned fluororesin. Specifically, the LED mounting body comprises an anisotropic conductive film 40 which has an LED element 20, a substrate 30, fluororesin and solder particles 41, and connects the electrodes 21 and 22 of the LED element 20 to the electrodes 31 and 32 of the substrate 30. The electrodes 21 and 22 of the LED element 20 and the electrodes 31 and 32 of the substrate 30 are joined by the solder particles 41, and the fluororesin is filled between the LED element 20 and the substrate 30. 【0043】 The LED element 20 comprises a first conductivity electrode 21 and a second conductivity electrode 22. When a voltage is applied between the first conductivity electrode 21 and the second conductivity electrode 22, carriers concentrate in the active layer within the element and recombine to produce light emission. The LED element 20 is not particularly limited, but for example, a blue LED having a peak wavelength of 400nm-500nm with high light energy, or an ultraviolet LED having a peak wavelength of 200nm-400nm can be suitably used. 【0044】 The substrate 30 has a first electrode 31 and a second electrode 32 on the substrate at positions corresponding to the first conductivity type electrode 21 and the second conductivity type electrode 22 of the LED element 20, respectively. 【0045】 As shown in Figure 2, the LED mounting structure has a metallic bond between the terminals (electrodes 21, 22) of the LED element 20 and the terminals (electrodes 31, 32) of the substrate 30 by soldering with solder particles 41, and a fluororesin is filled between the LED element 20 and the substrate 30. This increases the bonding strength between the LED element 20 and the substrate 30, and the fluororesin prevents the intrusion of moisture and other substances. In addition, the excellent resistance of the fluororesin to light energy provides excellent conductivity reliability. <3. Manufacturing method of connecting structure> 【0046】 [First Embodiment] The method for manufacturing the connecting structure in the first embodiment involves sandwiching an anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin between the electrodes of a first electronic component and a second electronic component, and connecting the electrodes of the first electronic component and the second electronic component by thermocompression bonding. The anisotropic conductive film is the same as described above, so its explanation is omitted here. 【0047】 The following describes a specific example of a method for manufacturing a connection structure, specifically a method for manufacturing an LED mounting assembly. The method for manufacturing an LED mounting assembly includes a temporary attachment step of temporarily attaching an anisotropic conductive film to a substrate, a mounting step of mounting LED elements onto the anisotropic conductive film, and a heat-pressing step of heat-pressing the LED elements and the substrate together via the anisotropic conductive film. 【0048】 Figure 3 is a cross-sectional view showing part of the temporary bonding process in the first embodiment, and Figure 4 is a cross-sectional view showing part of the mounting process in the first embodiment. The LED element 20 and the substrate 30 are the same as described above, so they are denoted by the same reference numerals and their description is omitted here. The anisotropic conductive film 50 is made of fluororesin with solder particles 51 dispersed in it, and is configured to be optimal for heat bonding conditions. 【0049】 In the temporary bonding process, as shown in Figure 3, the first surface of the anisotropic conductive film 50 from which the first film has been peeled off is temporarily bonded to the substrate, and the second film 54 is peeled off from the anisotropic conductive film 50. In the mounting process, as shown in Figure 4, the LED element 20 is placed on the second surface of the anisotropic conductive film 50 from which the second film 53 has been peeled off, and mounted. 【0050】 In the heat-pressing process, the LED element 20 is heat-pressed onto the substrate 30 using a heat-pressing tool. In the heat-pressing process, the pressure is preferably 1 MPa to 40 MPa, more preferably 1 MPa to 30 MPa, and even more preferably 1 MPa to 20 MPa. In the heat-pressing process, the pressure is preferably 150°C to 260°C, more preferably 150°C to 230°C, and even more preferably 150°C to 200°C. As a result, the fluororesin melts due to the heat of the heat-pressing tool, and the solder particles 51 melt while being sandwiched between the electrodes, thus achieving excellent conductivity, heat dissipation, and adhesion. 【0051】 [Second Embodiment] The method for manufacturing the connecting structure in the second embodiment involves sandwiching an anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin between the electrodes of the first electronic component and the electrodes of the second electronic component, and connecting the electrodes of the first electronic component and the electrodes of the second electronic component using a reflow oven. 【0052】 The following describes a specific example of a method for manufacturing a connection structure: a method for manufacturing an LED mounting assembly. The method for manufacturing an LED mounting assembly includes a temporary bonding step of temporarily bonding an anisotropic conductive film onto a substrate, a mounting step of mounting LED elements onto the anisotropic conductive film, and a reflow step of connecting the electrodes of the LED elements and the electrodes of the substrate using a reflow oven. 【0053】 Figure 5 is a cross-sectional view showing a part of the reflow process in the second embodiment. The LED element 20 and the substrate 30 are the same as described above, so they are denoted by the same reference numerals and their description is omitted here. The anisotropic conductive film 60 is made of fluororesin with solder particles 61 dispersed in it, and is configured to be optimal for reflow conditions. 【0054】 In the temporary bonding process, the first surface of the anisotropic conductive film 60 from which the first film has been peeled off is temporarily bonded to the substrate, and the second film is peeled off from the anisotropic conductive film 60. In the mounting process, the LED element 20 is placed on the second surface of the anisotropic conductive film 60 from which the second film has been peeled off, and mounted. 【0055】 In the reflow process, the electrodes of the LED element 20 and the electrodes of the substrate 30 are connected using a reflow oven. As the temperature of the reflow oven rises, the fluororesin melts, and the solder particles 61 are sandwiched between the electrodes by the weight of the LED element 20. When the temperature of the reflow oven is above the solder melting temperature of the solder particles 61, the solder particles 61 melt during this heating, and the electrodes of the LED element 20 and the electrodes of the substrate 30 are joined by cooling. In the reflow process, as an example, the heating is preferably performed at a temperature of 200°C to 280°C, more preferably at 210°C to 260°C, and even more preferably at 220°C to 250°C. As a result, the electrodes of the LED element 20 and the electrodes of the substrate 30 are joined, and excellent conductivity, heat dissipation, and adhesion can be obtained. [Examples] 【0056】 <4. Examples> The following describes in detail some embodiments of this technology. In these embodiments, LED mounting bodies were fabricated using the following connecting material AI, and their bonding strength, conductivity reliability, and degradation resistance were evaluated. However, this technology is not limited to these embodiments. The melting temperature (melting point) of the solder particles used in the connecting material may be determined using catalog values ​​or measured values ​​obtained by DSC measurement (heating speed, 10°C / min). 【0057】 [Anisotropic conductive film A] 100 parts by mass of fluororesin (product name: Dynion THV221GZ, manufactured by 3M Japan Limited, melting temperature 120°C), 50 parts by mass of solder particles (product name: L23, Senju Metal Industry Co., Ltd.) with an average particle size of 10 μm and a melting temperature of 140°C, and 5 parts by mass of rosin (product name: KE311, Arakawa Chemical Industries, Ltd.) were mixed in methyl ethyl ketone (MEK). This mixture was applied to a release-treated PET film using a bar coater, and then dried in an 80°C oven for 5 minutes to volatilize the MEK, thereby producing an anisotropic conductive film A with a thickness of 30 μm. 【0058】 [Anisotropic conductive film B] An anisotropic conductive film B was prepared in the same manner as in Example 1, except that solder particles with an average particle size of 5 μm and a melting temperature of 180°C (product name: MP6076, Senju Metal Co., Ltd.) were used as solder particles. 【0059】 [Anisotropic conductive film C] An anisotropic conductive film C was prepared in the same manner as in Example 1, except that solder particles with an average particle size of 10 μm and a melting temperature of 180°C (product name: MP6076, Senju Metal Co., Ltd.) were used as solder particles. 【0060】 [Anisotropic conductive film D] An anisotropic conductive film D was prepared in the same manner as in Example 1, except that solder particles with an average particle size of 25 μm and a melting temperature of 180°C (product name: MP6076, Senju Metal Co., Ltd.) were used as solder particles. 【0061】 [Anisotropic conductive film E] An anisotropic conductive film E was prepared in the same manner as in Example 1, except that solder particles with an average particle size of 10 μm and a melting temperature of 219°C (product name: M705, Senju Metal Industry Co., Ltd.) were used as solder particles. 【0062】 [Film F] Film F was manufactured in the same manner as in Example 1, except that solder particles and rosin were not included. [Anisotropic conductive film G] An anisotropic conductive film in which resin core conductive particles are dispersed in epoxy resin (Product name: CP369, Dexerials Corporation) [Anisotropic conductive paste H] Anisotropic conductive paste in which nickel particles are dispersed in epoxy resin (Product name: BP513, Dexerials Corporation) [Solder Paste I] Solder paste (Product name: M705-GRN360-K2V, Senju Metal Co., Ltd.) 【0063】 <4.1 Regarding joint strength> A blue LED mounting structure was fabricated using the connecting material AI, and the die shear strength was measured. 【0064】 [Measurement of die shear strength] Figure 6 is a cross-sectional view showing an overview of the die shear strength test. As shown in Figure 6, the die shear strength was measured using a die shear tester for an LED mounting sample in which an LED element 71 and a substrate 72 were joined with a connecting material 73. For each LED mounting sample, the die shear strength was measured initially and after a high-temperature, high-humidity continuous lighting test under the conditions of a tool 74 shear rate of 20 μm / sec and a temperature of 25°C. The high-temperature, high-humidity continuous lighting test involved continuous lighting under the conditions of a temperature of 85°C, humidity of 90%, and 1000 hours. 【0065】 <Example 1> A blue LED (IF=350mA, size 45mm square, peak wavelength 460nm) was mounted on a gold wiring-ceramic substrate using an anisotropic conductive film A. Specifically, anisotropic conductive film A was temporarily attached to the gold wiring-ceramic substrate, the LED chip was aligned and mounted, and then heat-pressed at 180°C for 60 seconds to produce an LED mounting sample. As shown in Table 2, the die shear strength was 28N / chip initially and 30N / chip after high-temperature, high-humidity continuous lighting tests. 【0066】 <Example 2> An LED mounting sample was prepared in the same manner as in Example 1, except that anisotropic conductive film B was used instead of anisotropic conductive film A. As shown in Table 2, the die shear strength was 36 N / chip initially and 33 N / chip during the high-temperature, high-humidity continuous lighting test. 【0067】 <Example 3> An LED mounting sample was prepared in the same manner as in Example 1, except that anisotropic conductive film C was used instead of anisotropic conductive film A. As shown in Table 2, the die shear strength was 39 N / chip initially and 41 N / chip after high-temperature, high-humidity continuous lighting tests. 【0068】 <Example 4> An LED mounting sample was prepared in the same manner as in Example 1, except that anisotropic conductive film D was used instead of anisotropic conductive film A. As shown in Table 2, the die shear strength was 46 N / chip initially and 42 N / chip after high-temperature, high-humidity continuous lighting tests. 【0069】 <Example 5> An LED mounting sample was prepared in the same manner as in Example 1, except that anisotropic conductive film E was used instead of anisotropic conductive film A. As shown in Table 2, the die shear strength was 38 N / chip initially and 37 N / chip after high-temperature, high-humidity continuous lighting tests. 【0070】 <Comparative Example 1> An LED mounting sample was prepared in the same manner as in Example 1, except that anisotropic conductive film F was used instead of anisotropic conductive film A. As shown in Table 2, the die shear strength was initially 0.5 N / chip. A high-temperature, high-humidity continuous lighting test was not performed because the LED electrodes and the substrate electrodes were not connected. 【0071】 <Comparative Example 2> An LED mounting sample was prepared in the same manner as in Example 1, except that anisotropic conductive film G was used instead of anisotropic conductive film A. As shown in Table 2, the die shear strength was initially 8N / chip. In addition, during the high-temperature, high-humidity continuous lighting test, the LED spontaneously peeled off during the test. 【0072】 <Comparative Example 3> An anisotropic conductive paste H was used instead of anisotropic conductive film A. After applying anisotropic conductive paste H to a gold wiring-ceramic substrate, an LED chip was aligned and mounted, and an LED mounting sample was prepared by heat bonding at 180°C for 60 seconds. As shown in Table 2, the die shear strength was initially 11 N / chip. In addition, during the high-temperature, high-humidity continuous lighting test, the LED spontaneously peeled off during the test. 【0073】 <Reference Example> Instead of anisotropic conductive film A, solder paste I was used. After applying solder paste I to a gold wiring-ceramic substrate, LED chips were aligned and mounted, and reflow soldering was performed at 260°C for 30 seconds to produce LED mounting samples. As shown in Table 2, the die shear strength was 45 N / chip initially and 46 N / chip after high-temperature, high-humidity continuous lighting tests. 【0074】 [Table 2] 【0075】 As shown in Comparative Example 1, adhesive strength cannot be obtained between the LED chip and the substrate using fluororesin alone. Furthermore, as shown in Comparative Examples 2 and 3, when the LED chip and substrate were bonded using an adhesive component, the adhesive strength was low from the initial stage, and the LED chip spontaneously peeled off due to photodegradation of the adhesive component during high-temperature, high-humidity continuous lighting tests. 【0076】 On the other hand, high bonding strength was obtained by using an anisotropic conductive film AE in which solder particles were dispersed in a fluororesin, as in Examples 1-5. Furthermore, as can be seen by comparing Examples 1 and 5, higher bonding strength was obtained when the difference between the melting temperature of the fluororesin and the melting temperature of the solder particles was large. Also, as can be seen by comparing Examples 3-4, higher bonding strength was obtained when the ratio of the average particle size of the solder particles to the film thickness was large. 【0077】 <4.2.1 Continuity Reliability of UV LED Mounting Components> A UV LED mounting structure was fabricated using connecting materials AE, G, and H, and the forward voltage was measured. 【0078】 [Measurement of forward voltage] The forward voltage was measured for each LED mounting sample, both initially and after a temperature cycling test (TCT). The temperature cycling test involved exposing the LED mounting sample to -40°C and 100°C atmospheres for 30 minutes each, performing 1000 cycles of this cycle. The Vf value of the LED mounting sample at If=20mA was then measured. 【0079】 Furthermore, the forward voltage of each LED mounting sample was measured initially and after high-temperature, high-humidity continuous lighting tests. In the high-temperature, high-humidity continuous lighting test, the LEDs were continuously lit under conditions of 85°C, 90% humidity, and 1000 hours, and the Vf value of the LED mounting sample was measured when If = 20mA. According to the evaluation standards of general LED manufacturers, it is desirable that the variation from the initial Vf value be less than 0.1V. 【0080】 <Example 6> An anisotropic conductive film A was used to mount an ultraviolet LED chip (product name: NS355C-2SAA, manufactured by Nitride Semiconductor, IF=20mA, peak wavelength 355nm) onto a gold wiring-ceramic substrate. Specifically, anisotropic conductive film A was temporarily attached to the gold wiring-ceramic substrate, the LED chip was aligned and mounted, and then heat-pressed at 180°C for 60 seconds to produce an LED mounting sample. As shown in Table 3, the Vf value was 3.59V initially, 3.58V after temperature cycling tests, and 3.61V after high-temperature, high-humidity continuous lighting tests. 【0081】 <Example 7> An LED mounting sample was prepared in the same manner as in Example 6, except that anisotropic conductive film B was used instead of anisotropic conductive film A. As shown in Table 3, the Vf value was 3.61V initially, 3.61V after the temperature cycling test, and 3.59V after the high-temperature, high-humidity continuous lighting test. 【0082】 <Example 8> An LED mounting sample was prepared in the same manner as in Example 6, except that anisotropic conductive film C was used instead of anisotropic conductive film A. As shown in Table 3, the Vf value was 3.60V initially, 3.59V after the temperature cycling test, and 3.62V after the high-temperature, high-humidity continuous lighting test. 【0083】 <Example 9> An LED mounting sample was prepared in the same manner as in Example 6, except that anisotropic conductive film D was used instead of anisotropic conductive film A. The Vf value was 3.58V initially, 3.63V after temperature cycling test, and 3.62V after high-temperature, high-humidity continuous lighting test. 【0084】 <Example 10> An LED mounting sample was prepared in the same manner as in Example 6, except that an anisotropic conductive film E was used instead of anisotropic conductive film A. The Vf value was 3.59V initially, 3.61V after temperature cycling test, and 3.58V after high-temperature, high-humidity continuous lighting test. 【0085】 <Comparative Example 4> An LED mounting sample was prepared in the same manner as in Example 6, except that anisotropic conductive film G was used instead of anisotropic conductive film A. The initial Vf value was 3.61V. In the temperature cycling test, the LED failed to light up after 500 hours. In the high-temperature, high-humidity continuous lighting test, the LED spontaneously peeled off during the test. 【0086】 <Comparative Example 5> An anisotropic conductive paste H was used instead of anisotropic conductive film A. After applying anisotropic conductive paste H to a gold wiring-ceramic substrate, an LED chip was aligned and mounted, and a heat-press bond was performed at 180°C for 60 seconds to create an LED mounting sample. The Vf value was 3.61V initially and 4.63V after the temperature cycling test. In addition, during the high-temperature, high-humidity continuous lighting test, the LED spontaneously peeled off during the test. 【0087】 [Table 3] 【0088】 In Comparative Example 4, when an epoxy resin-based anisotropic conductive film G was used to bond the UV LED chip to the substrate, the LED failed to light up after 500 hours in the temperature cycling test due to photodegradation of the resin. Furthermore, in the high-temperature, high-humidity continuous lighting test, the UV LED chip spontaneously peeled off. In Comparative Example 5, when an epoxy resin-based anisotropic conductive paste H was used to bond the UV LED chip to the substrate, the change from the initial Vf value after the temperature cycling test was large. Furthermore, in the high-temperature, high-humidity continuous lighting test, the UV LED chip spontaneously peeled off. 【0089】 On the other hand, when an anisotropic conductive film AE in which solder particles are dispersed in a fluororesin was used to bond the ultraviolet LED chip and the substrate, as in Example 6-10, excellent conductivity reliability was obtained. 【0090】 <4.2.2 On the Continuity Reliability of UV-C LED Packaging> A UV-C LED assembly was fabricated using connecting material C, and the forward voltage was measured. 【0091】 [Measurement of forward voltage] The forward voltage was measured for each LED mounting sample, both initially and after a high-temperature, high-humidity continuous lighting test. The high-temperature, high-humidity continuous lighting test involved continuous lighting under conditions of 85°C, 90% humidity, and 750 hours, and the Vf value was measured for each LED mounting sample at If=20mA. According to typical LED manufacturer evaluation standards, a variation of less than 0.1V from the initial Vf value is desirable. 【0092】 <Example 11> An anisotropic conductive film C was used to mount a UV-C LED chip (manufactured by DOWA, IF=20mA, peak wavelength 265nm) onto a gold wiring-ceramic substrate. Specifically, the anisotropic conductive film C was temporarily attached to the gold wiring-ceramic substrate, the LED chip was aligned and mounted, and then heated and pressed at 180°C for 60 seconds to produce an LED mounting sample. As shown in Table 4, the Vf value was 5.92V initially and 5.97V after high-temperature, high-humidity continuous lighting test. 【0093】 [Table 4] 【0094】 As in Example 11, when an anisotropic conductive film in which solder particles are dispersed in a fluororesin was used to bond an ultraviolet LED chip to a substrate, excellent conductivity reliability was obtained even for short-wavelength ultraviolet light called UV-C. 【0095】 <4.3 Regarding Degradation Resistance> After a high-temperature, high-humidity continuous lighting test, LED mounting samples were cut perpendicular to the substrate, and the cross-section was observed using a Scanning Electron Microscope (SEM) to evaluate the resin state. 【0096】 Figure 7 is a cross-sectional photograph of the connection part of the LED mounting sample in the initial stages of implementation for Comparative Example 2, and Figure 8 is a cross-sectional photograph of the connection part of the LED mounting sample in Comparative Example 2 after the high-temperature, high-humidity continuous lighting test. Figure 9 is a cross-sectional photograph of the connection part of the LED mounting sample in Example 11 after the high-temperature, high-humidity continuous lighting test. 【0097】 In the cross-sectional photographs shown in Figures 7-9, the lower part is the substrate electrode, the right part is the LED electrode, and the left part is the connecting material. As can be seen by comparing Figure 7 and Figure 8, in Comparative Example 2, which used an epoxy-based anisotropic conductive film, resin degradation occurred due to 460 nm blue light. 【0098】 On the other hand, in Example 11, which used an anisotropic conductive film in which solder particles were dispersed in a fluororesin, as shown in the cross-sectional photograph in Figure 9, no resin degradation occurred even when exposed to 265 nm UV-C, demonstrating excellent degradation resistance. [Explanation of Symbols] 【0099】 10 Anisotropic conductive film, 11 Solder particles, 12 First film, 13 Second film, 20 LED element, 21 First conductive electrode, 22 Second conductive electrode, 30 Substrate, 31 First electrode, 32 Second electrode, 40 Anisotropic conductive film, 41 Solder particles, 50 Anisotropic conductive film, 51 Solder particles, 53 Second film, 60 Anisotropic conductive film, 61 Solder particles, 71 LED element, 72 Substrate, 73 Connecting material, 74 Tool

Claims

[Claim 1] An anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin. [Claim 2] The anisotropic conductive film according to claim 1, wherein the melting temperature of the fluororesin is lower than the melting temperature of the solder particles. [Claim 3] The anisotropic conductive film according to claim 1 or 2, further comprising a tackifier. [Claim 4] The anisotropic conductive film according to any one of claims 1 to 3, wherein the fluororesin is a fluoroolefin copolymer having units based on fluoroolefins. [Claim 5] The anisotropic conductive film according to any one of claims 1 to 3, wherein the fluororesin is a tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer. [Claim 6] The anisotropic conductive film according to claim 3, wherein the tackifier is a rosin resin. [Claim 7] The anisotropic conductive film according to claim 6, wherein the amount of the tackifier is part by mass relative to 100 parts by mass of the fluororesin. [Claim 8] The first electronic component and The second electronic component, The device comprises a fluororesin and solder particles, and an anisotropic conductive film formed by connecting the electrodes of the first electronic component and the electrodes of the second electronic component. The electrodes of the first electronic component and the electrodes of the second electronic component are joined together by the solder particles. A connecting structure in which the fluororesin is filled between the first electronic component and the second electronic component. [Claim 9] The first electronic component is an LED element, The connection structure according to claim 8, wherein the second electronic component is a substrate. [Claim 10] A method for manufacturing a connection structure, comprising sandwiching an anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin between the electrodes of a first electronic component and a second electronic component, and connecting the electrodes of the first electronic component and the second electronic component by thermocompression bonding. [Claim 11] A method for manufacturing a connection structure, comprising sandwiching an anisotropic conductive film having a fluororesin and solder particles dispersed in the fluororesin between the electrodes of a first electronic component and a second electronic component, and connecting the electrodes of the first electronic component and the second electronic component by a reflow oven.

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