Filler-containing film, joined body and method for manufacturing the same

Abstract

To suppress resin flow of a core film having a through hole and restrict unnecessary movement of a filler, achieve good particle capturing property, when the core film is sandwiched between an insulation base layer and an adhesive layer, and two members are joined to each other by compression bonding such as thermal compression bonding, through a filler-containing film in which the filler is held on the through hole, and obtain a good indentation and achieve good conductivity between connection electrodes, when the filler-containing film is applied to a conductive film or an isotropic conductive film.SOLUTION: A filler-containing film, which has a core film having a through hole sandwiched between an insulation base layer and an adhesive layer, and has a filler held on the through hole, satisfies Expression (1): Od≥2×Pd-Ct, and Expression (2): 0.9×Pd≥Ct. In the expressions, Ct is thickness of the core film, Pd is the average particle diameter of the filler, and Od is an opening diameter of the through hole of the core film.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a filler-containing film. [Background technology]

[0002] Filler-containing films in which fillers are dispersed in a resin layer are used in a wide variety of applications, such as matte films, capacitor films, optical films, label films, antistatic films, conductive films, and anisotropic conductive films (Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4). When a filler-containing film is used by thermocompression bonding to an article, it is desirable in terms of optical properties, mechanical properties, or electrical properties to suppress the resin forming the filler-containing film from flowing unnecessarily during thermocompression bonding and to suppress uneven distribution of the filler. In particular, when conductive particles are contained as a filler and the filler-containing film is used as a conductive film or anisotropic conductive film for mounting electronic components, if the conductive particles are densely dispersed in the insulating resin layer so as to be compatible with high-density mounting of electronic components, excessive resin flow during mounting of electronic components causes the conductive particles to move unnecessarily and be unevenly distributed between terminals, which causes short circuits, and therefore it is required to suppress such excessive resin flow.

[0003] In response to such demands, an anisotropic conductive film has been proposed, which is obtained by laminating an insulating film with through holes in an adhesive layer, filling the through holes with conductive particles, and then laminating another adhesive layer (Patent Document 5). In this anisotropic conductive film, in order to suppress excessive resin flow in the insulating film during anisotropic conductive connection, the thickness of the insulating film is set to 0.4 to 1.0 times the conductive particle diameter, and further, the thickness of the insulating film is set to 1 mm. 2 The number of conductive particles per through hole is set to be 0.9 to 1.0 times the number of through holes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-15680 A [Patent Document 2] JP 2015-138904 A [Patent Document 3] JP 2013-103368 A [Patent Document 4] JP 2014-183266 A [Patent Document 5] JP2018-174069 Public Relations Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the anisotropic conductive film of Patent Document 5, factors for suppressing excessive resin flow in the insulating film are not sufficiently paid attention to factors other than "the relationship between the insulating film thickness and the conductive particle diameter" and "the relationship between the conductive particle density and the through hole density". Therefore, it is concerned that excessive resin flow in the insulating film cannot be sufficiently suppressed during anisotropic conductive connection, which leads to unnecessary movement of conductive particles, and the particle capture ability between the opposing electrodes is reduced, making it difficult to achieve good conductivity. There is also concern that the so-called "indentation", which is an indicator of the degree of anisotropic conductive connection, becomes unclear. There is also concern that a similar problem will occur when a core film having through holes is sandwiched between an insulating base layer and an adhesive layer, and two members are joined by compression, for example, thermocompression, via a filler-containing film in which a filler is held in the through holes.

[0006] The object of the present invention is to solve the problems of the conventional technology described above, and to suppress the resin flow of the core film and limit unnecessary movement of the filler when two components are joined by pressing, for example, thermocompression, via a filler-containing film in which a core film having through holes is sandwiched between an insulating base layer and an adhesive layer and filler is held in the through holes, thereby realizing good particle capture properties, and further, when the filler-containing film is applied to a conductive film or anisotropic conductive film, a good impression is obtained, and good conductivity is achieved between connecting electrodes. [Means for solving the problem]

[0007] The inventors focused on the relationship between the "core film thickness", "filler diameter" and "through hole opening diameter" and discovered that the above-mentioned object can be achieved by limiting these to a specific interrelationship, thereby completing the present invention.

[0008] That is, the present invention provides a filler-containing film in which a core film having through holes is sandwiched between an insulating base layer and an adhesive layer, and a filler is held in the through holes, the filler-containing film satisfying the following formulas (1) and (2).

[0009]

number

[0010] In the above formulas (1) and (2), C t is the thickness of the core film, and P d is the average particle size of the filler, and O d is the opening diameter of the through hole of the core film. When conductive particles are used as the filler, the filler-containing film can be used as a conductive film or an anisotropic conductive film.

[0011] The present invention also provides a bonded body in which a first member and a second member are bonded via the filler-containing film of the present invention, preferably a bonded body in which the first member is conductively or anisotropically conductively connected to the second member by the filler-containing film used as a conductive film or anisotropically conductive film. The present invention also provides a method for producing a bonded body in which the first member and the second member are bonded after the filler-containing film is similarly disposed between them, preferably a method for producing a connection structure in which the first member is conductively or anisotropically conductively connected to the second member by the filler-containing film used as a conductive film or anisotropically conductive film. In this production method, it is preferable that the terminal of the first member and the terminal of the second member are electrically connected by conductive particles. Effect of the Invention

[0012] The filler-containing film of the present invention focuses on the relationship between "core film thickness," "filler diameter," and "through-hole opening diameter," and limits these to a specific interrelationship. Therefore, when two members are joined via the filler-containing film by compression, for example, thermocompression, the resin flow of the core film is suppressed, unintended movement of the filler can be restricted, and good particle capture properties can be achieved. Moreover, when the filler-containing film is applied to a conductive film or anisotropic conductive film, good indentations can be obtained, and good conductivity can be achieved between connecting electrodes. [Brief description of the drawings]

[0013] [Figure 1A] FIG. 1A is a cross-sectional view of a filler-containing film. [Figure 1B] FIG. 1B is an enlarged cross-sectional view of a portion of the filler-containing film of FIG. 1A. [Figure 2A] FIG. 2A is an explanatory diagram of a method for producing a filler-containing film. [Figure 2B] FIG. 2B is an explanatory diagram of a method for producing a filler-containing film. [Figure 2C] FIG. 2C is an explanatory diagram of a method for producing a filler-containing film of an embodiment. [Figure 2D] FIG. 2D is an explanatory diagram of a method for producing a filler-containing film of an embodiment. [Figure 2E] FIG. 2E is an explanatory diagram of a method for producing a filler-containing film of an embodiment. [Figure 2F] FIG. 2F is an explanatory diagram of a method for producing a filler-containing film of an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An example of the filler-containing film of the present invention will now be described in detail with reference to the drawings. In the drawings, the same reference numerals denote the same or equivalent components.

[0015] <Overall Configuration of Filler-Containing Film 10> 1A is a cross-sectional view of a filler-containing film 10 of the present invention. This filler-containing film 10 has a structure in which a core film 3 having through holes th is sandwiched between an insulating base layer 1 and an adhesive layer 2, and a filler 4 is held in the through holes th, and is characterized in that it satisfies the following formulas (1) to (2), preferably formulas (1') and (2').

[0016]

number

[0017]

number

[0018] In these formulas, as can be seen from FIG. 1B, which is a partially enlarged cross-sectional view of the periphery of the filler 4 of the filler-containing film 10 of the present invention, C t is the thickness of the core film [μm], and P d represents the average particle size of the filler [μm], and O d represents the opening diameter [μm] of the through hole in the core film.

[0019] <Insulating base layer 1> The insulating base layer 1 constituting the filler-containing film 10 of the present invention is a layer that serves as a base for forming a core film thereon when producing the filler-containing film 10. Such an insulating base layer 1 may be composed of a single insulating resin layer, or may be composed of a laminate of multiple insulating resin layers. In addition, it is preferable that the insulating base layer 1 exhibits adhesiveness.

[0020] (Resin composition constituting insulating base layer 1) The resin composition constituting the insulating base layer 1 can be appropriately selected according to the application of the filler-containing film, and examples thereof include a thermoplastic resin composition, a high-viscosity adhesive resin composition, and a curable resin composition. For example, when the filler-containing film is made into a conductive film or an anisotropic conductive film, a curable resin composition formed from a polymerizable compound and a polymerization initiator can be used, similar to the resin composition forming the insulating resin layer of a conventional conductive film or an anisotropic conductive film. In this case, a thermal polymerization initiator may be used as the polymerization initiator, a photopolymerization initiator may be used, or they may be used in combination. For example, a cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermal polymerizable compound, a photoradical polymerization initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. A thermal anionic polymerization initiator may be used as the thermal polymerization initiator. As the thermal anionic polymerization initiator, it is preferable to use a microcapsule-type latent curing agent in which an imidazole modified body is used as the core and the surface is coated with polyurethane.

[0021] (Minimum melt viscosity of insulating base layer 1) The minimum melt viscosity of the insulating base layer 1 may be 200 Pa·s or more, preferably 1500 Pa·s or more, more preferably 2000 Pa·s or more, even more preferably 3000 Pa·s or more, and preferably 15000 Pa·s or less, more preferably 10000 Pa·s or less, and particularly preferably 8000 Pa·s or less, in order to suppress unnecessary movement of the filler 4 due to resin flow when the filler-containing film 10 is pressure-bonded to an article, for example, by thermocompression bonding, and to induce a moderate resin flow. As an example, the low melt viscosity can be determined using a rotational rheometer (manufactured by TA instruments) with a measurement pressure of 5 g kept constant and a measurement plate with a diameter of 8 mm. More specifically, it can be determined by setting the temperature range to 30 to 200 ° C, the heating rate to 10 ° C / min, the measurement frequency to 10 Hz, and the load fluctuation to the measurement plate to 5 g. The minimum melt viscosity can be adjusted by changing the type and amount of fine solid matter as a melt viscosity adjuster, the adjustment conditions of the resin composition, etc.

[0022] (Thickness of insulating base layer 1) The thickness of the insulating base layer 1 is set to be equal to or larger than the average particle diameter P of the filler 4 in order to stably hold the core film 3 and the filler 4 together. d It is preferably 0.6 times or more, more preferably 1.2 times or more, and particularly preferably 1.5 times or more, of the average particle diameter of the filler 4. The upper limit of the thickness of the insulating base layer 1 is preferably 10 times or less, more preferably 5 times or less, of the average particle diameter of the filler 4 so as to prevent unnecessary movement of the filler 4 due to resin flow. The layer thickness can be measured by a known thickness gauge or film thickness measuring device.

[0023] (Adhesive strength of insulating base layer 1) The insulating base layer 1 preferably has an adhesive strength that allows temporary compression before compression to an article to which the filler-containing film is to be compressed, for example, thermocompression-bonded. The adhesive strength can be measured in accordance with JIS Z 0237, and can also be measured as tack strength by a probe method in accordance with JIS Z 3284-3 or ASTM D 2979-01. The tack strength of the adhesive layer 2 constituting the filler-containing film 10 by the probe method is preferably 1.0 kPa (0.1 N / cm) when measured, for example, at a probe pressing speed of 30 mm / min, a pressure of 196.25 gf, a pressure time of 1.0 sec, a peel speed of 120 mm / min, and a measurement temperature of 23°C ± 5°C. 2 ) or more, more preferably 1.5 kPa (0.15 N / cm 2 ) or more, particularly preferably 3.0 kPa (0.3 N / cm 2 )That's all.

[0024] The adhesive strength of the filler-containing film can also be determined according to the adhesive strength test described in JP 2017-48358 A. In this adhesive strength test, for example, when the filler-containing film 10 is sandwiched between two glass plates, one glass plate is fixed, and the other glass plate is peeled off at a peeling speed of 10 mm / min and a test temperature of 50° C., by strengthening the adhesive state between the fixed glass plate and the filler-containing film, it is possible to measure the adhesive strength between the glass plate being peeled off and the surface of the filler-containing film attached to the glass plate. The adhesive strength (adhesive strength) measured in this way is preferably 1 N / cm 2 (10kPa) or more, more preferably 10N / cm 2 (100 kPa) or more. This is the adhesive force between the surface of the filler-containing film in the peeling direction and the article to be peeled off.

[0025] In addition, the adhesive strength of a filler-containing film can also be determined by a test in which one end of a test piece is aligned and glued together (pasted), and the other end is pulled up to peel the test piece off. The adhesive strength measured by this test method is equivalent to that of the above adhesive strength test (1 N / cm 2 (10 kPa) or more) may be acceptable if the adhesive strength measured by the above adhesive strength test is sufficiently large (e.g., 10 N / cm 2 (100 kPa or more), and the adhesive strength in this test method should be 10% or more of the adhesive strength in the above-mentioned adhesive strength test.

[0026] Such adhesion can be adjusted by appropriately adjusting the resin composition constituting the insulating base layer and by improving the smoothness of the insulating base layer that forms the outer surface of the filler-containing film by the manufacturing method of the filler-containing film described below.

[0027] <Adhesive layer 2> The adhesive layer 2 constituting the filler-containing film 10 of the present invention is a layer for temporarily bonding to an article using the filler-containing film 10. Such an adhesive layer 2 may be composed of a single insulating resin layer, or may be composed of a laminate of a plurality of insulating resin layers.

[0028] (Resin composition constituting adhesive layer 2) The resin composition constituting the adhesive layer 2 is appropriately selected according to the application of the filler-containing film, as in the insulating base layer 1, and examples thereof include a thermoplastic resin composition, a high-viscosity adhesive resin composition, or a curable resin composition. For example, when the filler-containing film is a conductive film or an anisotropic conductive film, a curable resin composition formed from a polymerizable compound and a polymerization initiator can be used, as in the resin composition forming the adhesive layer of a conventional conductive film or anisotropic conductive film. In this case, a thermal polymerization initiator may be used as the polymerization initiator, a photopolymerization initiator may be used, or they may be used in combination. For example, a cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermal polymerizable compound, a photoradical polymerization initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. A thermal anionic polymerization initiator may be used as the thermal polymerization initiator. As the thermal anionic polymerization initiator, it is preferable to use a microcapsule-type latent curing agent in which an imidazole modified body is used as a core and the surface is coated with polyurethane.

[0029] (Minimum melt viscosity of adhesive layer 2) The minimum melt viscosity of the adhesive layer 2 may be the same as that of the insulating base layer 1 described above. It can be intentionally set lower or higher than that of the insulating base layer 1. By adjusting the minimum melt viscosity (and thickness) of the insulating base layer 1 and the adhesive layer 2, it is possible to precisely control the resin flow when the filler-containing film 10 is bonded to an article, for example, by thermocompression bonding, and it is expected that the film can be applied to various uses. When used in a conductive film or anisotropic conductive connection, it is possible to more precisely suppress unnecessary movement of the filler (i.e., conductive particles).

[0030] (Thickness of adhesive layer 2) The thickness of the adhesive layer 2 may be the same as that of the insulating base layer 1 described above. It can be intentionally set lower or higher than the insulating base layer 1. Specifically, it is preferably 0.1 μm or more, more preferably 0.5 μm or more. When used for pasting, it is preferable to make it thin. It may be 20 μm or more for filling. If it is too thick, there is a concern that the resin may protrude when it is wound, so it is preferably 50 μm or less. In this way, the upper limit can be appropriately set according to the purpose.

[0031] (Adhesive strength of adhesive layer) The adhesive layer 2 preferably has an adhesive strength that allows temporary pressure-bonding before pressure-bonding to an article to which the filler-containing film is to be pressure-bonded, for example, thermocompression-bonded. The adhesive strength of such an adhesive layer 2 may be the same as that of the insulating base layer 1, may be stronger than that of the insulating base layer 1, or may be weaker. The adhesive strength of the adhesive layer 2 and that of the insulating base layer 1 may be optimized from the viewpoints of whether the surface to be attached to the article is the insulating base layer 1 or the adhesive layer 2, and the level of adhesive strength required for the article to be placed thereon.

[0032] <Core Film 3> The core film 3 constituting the filler-containing film 10 of the present invention has through holes th for filling with the filler 4, and is a layer for suppressing unintended movement of conductive particles due to resin flow in the insulating base layer 1 and the adhesive layer 2, and functions as a spacer sheet. Such a core film 3 may be composed of a single insulating resin layer, or may be composed of a laminate of multiple insulating resin layers.

[0033] (Resin composition constituting the core film) The resin composition constituting the core film 3 is appropriately selected depending on the application of the filler-containing film 10, and examples thereof include thermoplastic resin compositions and high-viscosity adhesive resin compositions containing phenoxy resin, polyimide resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, polyvinyl acetate resin, etc., and curable resin compositions containing epoxy resin, acrylic resin, etc., or mixtures thereof.

[0034] (Melt viscosity of core film 3) The melt viscosity of the core film 3 is set to a temperature range during compression bonding in order to suppress unnecessary movement of the filler 4 due to resin flow when the filler-containing film 10 is compressed, for example, by thermocompression bonding. In this case, the melt viscosity is 1.1 times, more preferably 1.2 times or more, the minimum melt viscosity of the insulating base layer 1. The melt viscosity can be determined, for example, by using a rotational rheometer (manufactured by TA Instruments) with a measurement pressure of 5 g kept constant and a measurement plate with a diameter of 8 mm. More specifically, the melt viscosity can be determined in a temperature range of 30 to 250°C, at a temperature rise rate of 10°C / min, a measurement frequency of 10 Hz, and a load fluctuation of 5 g on the measurement plate. The melt viscosity can be adjusted by changing the type and amount of fine solid matter used as a melt viscosity adjuster, the adjustment conditions of the resin composition, etc.

[0035] (Thickness of core film 3) The thickness of the core film 3 is set to be equal to or larger than the average particle diameter P d This will be discussed later.

[0036] (Through hole of core film 3) The core film 3 has a through hole th formed therein for filling and holding the filler 4. The through hole th is open on both the adhesive layer 2 side and the insulating base layer 1 side. Usually, the diameter of the opening on the adhesive layer 2 side and the opening on the insulating base layer 1 side are the same size.

[0037] Opening diameter O of through hole th d is the thickness C of the core film 3, which is determined taking into consideration the application of the filler-containing film. t and the average particle size of filler 4, P d If the opening diameter is too small, the filler cannot be accommodated. d is 1.1 times or more, preferably 1.2 times or more, and more preferably 1.3 times or more, the average particle diameter of the filler. d If is too large compared to the average particle size of the filler, the filler cannot be retained, so the opening diameter O d is 2.5 times or less, preferably 2.2 times or less, and more preferably 2.1 times or less, the average particle size of the filler. In the present invention, it can be selected from this range depending on the thickness of the core film.

[0038] Such through holes th may be provided in the core film 3 in a random pattern or may be arranged in a regular pattern. Such a through hole pattern is essentially synonymous with the pattern of filler in the filler-containing film 10. Examples of regular patterns include lattice arrangements such as square lattices, rectangular lattices, and oblique lattices. A combination of multiple lattices of different shapes may also be used. The regular pattern has the advantage of making quality control easier. Through hole rows in which through holes are arranged in a straight line at a predetermined interval may be arranged in parallel at a predetermined interval. A region in which the through holes th are densely arranged and a region in which the through holes th are sparsely arranged may be regularly repeated. When the filler-containing film is a conductive film or an anisotropic conductive film, it is more preferable to arrange the through holes in a regular arrangement spaced apart from each other in order to achieve both capture stability and short circuit suppression at the terminal. Whether the through holes th are regularly arranged or not can be determined by, for example, observing whether a predetermined arrangement of the through holes or the filler is repeated in the longitudinal direction of the film (the winding direction when the filler-containing film is wound).

[0039] The filler filling rate in the through holes can be calculated as {(number of fillers / number of through holes)×100(%)}. This can be calculated by observing the film surface field in the same manner as the number density described below. The filler filling rate may be 95% or more, preferably 98% or more, and more preferably 99.5% or more. It is desirable that the remaining filler (residual rate) that is not filled in the filler is small (close to zero), but in practice, the residual rate may be less than 2%, preferably less than 1%, and more preferably less than 0.5% relative to the number of through holes th. This is because if removal work is performed to bring the residual rate closer to zero, it may be the cause of defects on the film surface.

[0040] The distance between the through holes th can be determined according to the objects to be connected and the purpose of use. The density of the through holes th is usually 10 pieces / mm 2 More than 30 pieces / mm 2 More than 500,000 particles / mm is preferable. 2 It is sufficient if it is less than 250,000 pieces / mm 2 It is preferable that the number of particles is 100,000 or less per mm. 2 The number density can be measured by observing the film surface with a microscope. The observation area during the microscope observation is 2 mm 2 More than 10mm, preferably 2 More preferably, it is equal to or greater than this.

[0041] The number density of the through holes th (i.e., filler) may be obtained by observing with a metal microscope, or by measuring an observed image using image analysis software (e.g., WinROOF (manufactured by Mitani Shoji Co., Ltd.) or Azo-kun (registered trademark) (manufactured by Asahi Kasei Engineering Co., Ltd.)). The observation method and measurement technique are not limited to those described above.

[0042] In the present invention, the size of the through holes is unified, so that the effect of the invention can be more prominent. To achieve this, it is desirable that the size and depth of the opening of the through holes satisfy the following conditions. That is, in the filler-containing film, when the total observation area is 1 mm 2More than 2mm, preferably 2 In the above, it is desirable that 95% or more, preferably 98% or more, more preferably 99.5% or more of the total number of through holes contained in a region having 1000 or more through holes (preferably 2000 or more) have the same size and depth of the opening. Here, "matching" in "the size and depth of the openings are the same" means that the size and depth of the opening of a certain through hole are within ±15%, preferably ±10%, more preferably ±5% of the average size and average depth of the openings of the through holes contained in a predetermined region, taking into account measurement errors. Note that the size of the opening may be the diameter when the area of ​​the opening is converted into a circle, since there are openings with different shapes.

[0043] <Filler 4> In the present invention, the filler 4 is appropriately selected from known inorganic fillers (metal particles, metal oxide particles, metal nitride particles, etc.), organic fillers (resin particles, rubber particles, etc.), and fillers containing a mixture of organic and inorganic materials (for example, particles whose core is made of a resin material and whose surface is metal-plated (metal-coated resin particles), conductive particles with insulating fine particles attached to their surfaces, conductive particles with their surfaces insulated, etc.) according to the performance required for the application, such as hardness and optical performance. For example, silica filler, titanium oxide filler, styrene filler, acrylic filler, melamine filler, various titanates, etc. can be used in optical films and matte films. For films for capacitors, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, calcium titanate, strontium titanate, barium titanate, barium titanate zirconate, lead titanate zirconate, and mixtures thereof can be used. For adhesive films, polymeric rubber particles, silicone rubber particles, etc. can be contained. Conductive films and anisotropic conductive films contain conductive particles. Examples of conductive particles include metal particles such as nickel, cobalt, silver, copper, gold, and palladium, alloy particles such as solder, metal-coated resin particles, and metal-coated resin particles with insulating fine particles attached to the surface. Two or more types can be used in combination. Among them, metal-coated resin particles are preferred because the resin particles repel each other after connection, making it easier to maintain contact with the terminal and stabilizing the conductive performance. In addition, the surfaces of the conductive particles may be subjected to an insulating treatment using a known technique that does not impair the conductive characteristics.

[0044] (Average particle size of filler 4) In the present invention, the average particle diameter P of the filler 4 dcan be determined depending on the application of the filler-containing film. For example, when the filler-containing film is used as a conductive film or anisotropic conductive film, in order to improve the pressing accuracy of the filler during the production of the filler-containing film, it is preferably 1 μm or more, more preferably 1.4 μm or more, and particularly preferably 2.5 μm or more. There is no particular upper limit, but in order to suppress the effect of the displacement of the filler during the production of the filler-containing film, it is preferably 200 μm or less, more preferably 50 μm or less, and particularly preferably 30 μm or less. The average particle diameter P of the filler 4 d can be obtained from a planar image or a cross-sectional image. The average particle size of the filler as raw material particles before being incorporated into the filler-containing film can be obtained using a wet flow type particle size / shape analyzer FPIA-3000 (manufactured by Malvern Instruments). When fine particles such as insulating fine particles are attached to the filler, the particle size is determined to be the diameter excluding the fine particles.

[0045] Average particle size P of filler in filler-containing film d The CV value (standard deviation / average) is preferably 20% or less. This makes it easier for the filler-containing film to be pressed evenly when it is pressed onto an article, and prevents the pressing force from concentrating locally. Therefore, when the filler-containing film is configured as a conductive film or anisotropic conductive film, the stability of the connection is improved, and after the connection, the connection state can be accurately evaluated by observing the indentation and the sandwiched state of the filler. Specifically, in an inspection after conductive connection or anisotropic conductive connection of electronic components using a conductive film or anisotropic conductive film, the connection state can be accurately confirmed by observing the indentation and the sandwiched state of the conductive particles, regardless of whether the terminal size is relatively large (FOB, etc.) or relatively small (COG, etc.). Therefore, it is expected that the inspection after conductive connection or anisotropic conductive connection will be easier, and the productivity of the connection process will be improved.

[0046] On the other hand, in a cross-sectional view of the filler-containing film cut in the film thickness direction (FIG. 1A), it is preferable that the apex of each filler in the film thickness direction is flush with a plane parallel to the interface between the insulating base layer 1 and the core film 3. This makes it easy to uniformly press-bond the filler-containing film to an article.

[0047] <Relationship between core film thickness, filler diameter, and through-hole opening diameter of core film> As described above, the filler-containing film 10 of the present invention described above has a relationship between the "core film thickness", the "filler diameter" and the "through hole opening diameter" that satisfies the following formulas (1) and (2), preferably formulas (1') and (2').

[0048]

number

[0049]

number

[0050] (Meaning of formulas (1) and (1')) In the present invention, the reason for focusing on the "interrelationship between the core film thickness, the filler diameter, and the through-hole opening diameter of the core film" is that in order to hold the filler with high precision after clamping, the opening diameter and thickness, i.e., the amount of movement of the filler in the film surface direction and the amount of movement of the filler in the film thickness direction, are essential. Specifically, the through-hole opening diameter O d is simply the average particle diameter P d 2 times the core film thickness C t The reason for setting it in this way is that by increasing the amount of movement of the filler toward the film during clamping, the filler fits within the opening diameter and becomes easier to clamp (crush). In other words, it gives the filler a certain degree of freedom in the film plane direction. Furthermore, the through hole opening diameter O d is the average particle size P of filler 4 so as to satisfy the formula dThe distance is set to less than twice the distance. This is set in order to adjust the amount of movement in the film thickness direction (compressed state, crushed state) according to the amount of movement of the filler in the film plane direction. In other words, after the filler is sandwiched, the surface of the core film that supports the filler (the inner surface of the through hole) is kept within a certain amount relative to the filler.

[0051] (Meaning of formulas (2) and (2')) In the present invention, the reason for focusing on the "relationship between the filler diameter and the core film thickness" is that, as described above, the filler and the inner surface of the through hole (i.e., the core film thickness) require a minimum area required for holding the filler. Specifically, if the core film is too thick compared to the filler, the force applied to the filler is reduced, which adversely affects the clamping. Therefore, the thickness C of the core film 3 is set to 100 mm. t , the average particle size P of filler 4 d The thickness C of the core film 3 is set to 0.9 times or less, preferably 0.8 times or less. If the core film is too thin compared to the filler, the above-mentioned core film will have difficulty in suppressing the movement of the filler toward the film surface direction, and it will be difficult to precisely position the filler after the film is pressed. t , the average particle size P of filler 4 d It is preferably set to 0.3 times or more, and more preferably 0.4 times or more.

[0052] <Method of manufacturing filler-containing film> The filler-containing film 10 of the present invention can be produced as follows: First, an insulating base layer-forming composition 1' is applied to a release substrate 20 having a smooth surface such as a PET film (FIG. 2A), and then dried in a conventional manner to form an insulating base layer 1 (FIG. 2B).

[0053] Next, a core film 3 having through holes th formed therein by laser processing, photolithography processing, stamp processing or the like is laminated on the insulating base layer 1 by a known method (FIG. 2C).

[0054] Next, the filler 4 is sprayed onto the core film 3, and the filler 4 is filled into the through-holes th using a squeegee or the like, and the filler 4 that is not filled into the through-holes th is removed by air blowing or the like (FIG. 2D).

[0055] Finally, the adhesive layer-forming composition 2' is applied onto the core film 3 (FIG. 2E) and dried in a conventional manner to form the adhesive layer 2 (FIG. 2F). This makes it possible to obtain a filler-containing film equipped with a release substrate 20, and by removing the release substrate 20, the filler-containing film 10 shown in FIG. 1A can be obtained.

[0056] <How to use filler-containing film> The filler-containing film of the present invention can be used by being attached to an article in the same manner as the conventional filler-containing film, and there is no particular restriction on the article to be attached. Therefore, a bonded body in which a first member and a second member are bonded via a filler-containing film, and a method for manufacturing a bonded body by disposing a filler-containing film between a first member and a second member and bonding them, are also part of the present invention. For example, when the filler-containing film is configured as a conductive film or anisotropic conductive film, a pressure bonding tool, for example a thermocompression bonding tool, can be used to make a conductive connection or anisotropic conductive connection between a first electronic component such as a semiconductor element using a PN junction (a power generation element such as a solar cell, an imaging element such as a CCD, a light-emitting element, a Peltier element), other various semiconductor elements, an IC chip, an IC module, or an FPC, and a second electronic component such as an FPC, a glass substrate, a plastic substrate, a rigid substrate, or a ceramic substrate, and the filler-containing film can also be used for electronic components for purposes other than conductive connection or anisotropic conductive connection. The surface of the article to which the filler-containing film is bonded may be smooth or may have a step or a convex shape.

[0057] There are no particular limitations on the shape, size, or use of the first and second electronic components connected by the conductive film or anisotropic conductive film. These electronic components may be small and have narrow terminal sizes, and high-precision alignment may be required for mounting the electronic components. For example, the bump area may be several tens of μm2 ~several thousand μm 2 Miniaturized electronic components (such as mini LEDs and micro LEDs) can also be connected. On the other hand, electronic components with large external sizes can be mounted using conductive films or anisotropic conductive films. The mounted electronic components may be divided into small pieces for use. When used in large TVs, the filler-containing film may be attached to one side for 1 m or more, for example, 4.5 m or more. In this case, in addition to using the filler-containing film as a conductive film or anisotropic conductive film, it may also be used as a spacer film using the filler as a spacer.

[0058] The filler-containing film of the present invention, for example, the conductive film or the anisotropic conductive film, may be used to stack IC chips or wafers to form a multilayer structure. The electronic components connected with the conductive film or the anisotropic conductive film of the present invention are not limited to the above-mentioned examples of electronic components. The conductive film or the anisotropic conductive film can be used for various electronic components that have become more diverse in recent years. The present invention includes various articles, particularly film attachment bodies to which the filler-containing film of the present invention is attached, and particularly includes a connection body in which a first electronic component and a second electronic component are connected via a conductive film or anisotropic conductive film.

[0059] The method of attaching the filler-containing film to the article can be pressure bonding, for example, thermocompression bonding, depending on the application of the filler-containing film, or light irradiation may be used during attachment. One example of using light irradiation is to separate the filler-containing film according to the laser lift-off method described in JP 2022-151816 A and then transfer it. The resin material and adhesive material to be used to make the filler-containing film suitable for the laser lift-off method can be selected from those described in JP 2022-151816 A and used.

[0060] A more specific method of using the filler-containing film as a conductive film or anisotropic conductive film is, for example, when the first electronic component is an IC chip and the second electronic component is a substrate, generally, the first electronic component is placed on the pressure tool side and the second electronic component is placed on a stage facing the first electronic component, a conductive film or anisotropic conductive film is attached to the second electronic component in advance, and the first electronic component and the second electronic component are thermocompression-bonded using the pressure tool. In this case, a conductive film or anisotropic conductive film may be attached to the first electronic component in advance, and the first electronic component is not limited to an IC chip.

[0061] When connecting the first electronic component and the second electronic component by pressure bonding, for example, thermocompression bonding, the resin around the conductive particles may be removed beforehand before the pressure bonding, if necessary, and the temporary pressure bonding may be performed. This reduces the influence of the resin flow that occurs when the conductive film or the anisotropic conductive film is pressure bonded, for example, thermocompression bonded, to an article such as an electronic component, and can suppress unnecessary flow of the conductive particles. Specifically, when performing the temporary pressure bonding in which one electronic component to be connected is attached to one side of the conductive film or the anisotropic conductive film and the other electronic component is attached to the other side of the conductive film or the anisotropic conductive film, the electronic components are pressed with a pressure tool to partially remove the resin between the electronic components, and then the electronic components are connected to each other by pressing, for example, thermocompression, as the main pressure bonding (hereinafter, the connection method in which pressing is performed not only during the main pressure bonding but also during the temporary pressure bonding is referred to as a two-stage pressing connection). WO2016 / 143789 describes making a connection by two-stage pressing using a conductive film or anisotropic conductive film in which conductive particles are randomly dispersed. When connecting electronic components using a conductive film or anisotropic conductive film in which conductive particles are regularly arranged, as in the present invention, making such a connection by two-stage pressing can significantly reduce unwanted flow of conductive particles during compression bonding, for example during thermocompression bonding. EXAMPLES

[0062] The present invention will be described in detail below with reference to examples. The formulations of the resin composition for forming an insulating base layer, the resin composition for forming a core film, and the resin composition for forming an adhesive layer used in the examples are shown below.

[0063] <Formulation of Resin Composition for Forming Insulating Base Layer> Phenoxy resin (YP-50, Nippon Steel Chemical & Material Co., Ltd.) 40 parts by mass Silica filler (Aerosil R805, Nippon Aerosil Co., Ltd.) 25 parts by mass Liquid epoxy resin (jER828, Mitsubishi Chemical Corporation) 30 parts by mass Silane coupling agent (KBM-403, Shin-Etsu Chemical Co., Ltd.) 2 parts by mass Thermal cationic polymerization initiator (SI-60L, Sanshin Chemical Industry Co., Ltd.) 3 parts by mass

[0064] <Formulation of resin composition for forming core film> Phenoxy resin (PKFE, Tomoe Kogyo Co., Ltd.) 70 parts by mass Fumed silica (RY200, Nippon Aerosil Co., Ltd.) 30 parts by weight

[0065] <Formulation of Resin Composition for Forming Adhesive Layer> Phenoxy resin (YP-50, Nippon Steel Chemical & Material Co., Ltd.) 40 parts by mass Silica filler (Aerosil R805, Nippon Aerosil Co., Ltd.) 5 parts by mass Liquid epoxy resin (jER828, Mitsubishi Chemical Corporation) 50 parts by mass Silane coupling agent (KBM-403, Shin-Etsu Chemical Co., Ltd.) 2 parts by mass Thermal cationic polymerization initiator (SI-60L, Sanshin Chemical Industry Co., Ltd.) 3 parts by mass

[0066] Examples 1 to 3 The above-mentioned resin composition for forming an insulating base layer and the resin composition for forming an adhesive layer were prepared on a release film (50 μm thick) made of polyethylene terephthalate with a release treatment on the surface, and these resin compositions were used to obtain an insulating base layer film having a thickness of 6 μm and an adhesive layer film having a thickness of 1.0 μm in the same manner as in Example 3 of Japanese Patent No. 6187665. In addition, a core film having a through hole with an opening diameter Od [μm] and a layer thickness Ct [μm] in Table 1 was obtained by preparing a coating liquid (diluted with a general-purpose solvent to a solid content of 20%) from a mixture of the above-mentioned resin composition for forming a core film, and then preparing a mold substantially similar to the mold described in paragraph 0111 of Japanese Patent No. 6187665 using transparent polycarbonate pellets, applying the above-mentioned coating liquid to the mold, and then leaving it in a dryer at 60 ° C. for 5 minutes to dry.

[0067] Conductive particles (Sekisui Chemical Co., Ltd., Micropearl (metal-coated resin particles), average particle size Pd [3.40 μm]) were prepared as the filler. After laminating the core film and the insulating base layer film, the through holes were filled with filler, and an adhesive layer film was laminated. The film lamination and filler filling were performed in substantially the same manner as in Japanese Patent No. 6187665. In this manner, the anisotropic conductive films of Examples 1 to 3 were produced as filler-containing films. The number density of the filler was 28,000 particles / mm 2 It was.

[0068] <Evaluation> The obtained filler-containing film was tested and evaluated for the filler's "immobility" ("particle capture ability" when the filler-containing film is used as an anisotropic conductive film), "indentation," and "conductivity (conductive resistance)" as described below.

[0069] (immobility) In order to evaluate the immobility of the filler, the particle capture property was evaluated. Specifically, the filler-containing film of each Example and Comparative Example was sandwiched between an IC for evaluating particle capture property and a glass substrate (ITO wiring) with a corresponding terminal (bump) pattern, with the alignment shifted by 6 μm, and heated and pressed (180° C., 60 MPa, 5 seconds) to create a connection structure for evaluation. In this connection structure, the number of captured conductive particles was measured for 100 pieces in a 6 μm×66.6 μm area where the bump of the evaluation IC and the terminal of the glass substrate overlap, the minimum number of captured conductive particles was obtained, and the evaluation was performed according to the following particle capture property evaluation criteria. The obtained results are shown in Table 1. For immobility, it is desirable to have an A or B rating in practical use.

[0070] IC for evaluating particle capture External size 1.6×29.8mm Thickness 0.3mm Bump specifications: Size 12μm×66.6μm, bump pitch 22μm (L / S=12μm / 10μm), bump height 12μm

[0071] Immobility (particle capture) evaluation criteria A: Minimum number of captures is 5 or more B: Minimum capture number is 3 or more but less than 5 C: Minimum capture number is 1 or more and less than 3 D: Minimum capture count is 0

[0072] (Indentation) The average particle size of 200 conductive particles in the connection structure for evaluating immobility was examined, and the percentage of conductive particles whose average particle size after compression was 80% or less of the average particle size before compression was calculated and evaluated according to the following indentation evaluation criteria. In practical terms, an A or B rating is preferable.

[0073] Indentation evaluation criteria Rank Criteria A: 80% or more B: 60% or more but less than 80% C: Less than 60%

[0074] (conductivity) The anisotropic conductive film as the filler-containing film of each example was sandwiched between an IC for evaluating the conductive properties and a glass substrate, and heated and pressurized (170°C, 20 MPa, 10 seconds) to prepare a connection structure for evaluation, and the initial conductive resistance was measured and evaluated according to the following conductivity evaluation criteria. The obtained results are shown in Table 1. For practical purposes, the conductivity is required to be rated A or B.

[0075] Here, the terminal (bump) patterns of the evaluation IC and the glass substrate correspond to each other, and their sizes are as follows: When connecting the evaluation IC and the glass substrate, the longitudinal direction of the anisotropic conductive film was aligned with the transverse direction of the bump.

[0076] Conduction characteristic evaluation IC External dimensions: 1.8×20.0mm Thickness: 0.5mm Bump specifications: Width 30μm x length 85μm, distance between bumps 50μm, bump height 15μm

[0077] Glass substrate (Ti / Al wiring) Glass material: Corning 1737F External size: 30×50mm Thickness: 0.5mm

[0078] Continuity evaluation Rank Criteria A: Initial conduction resistance is less than 1.0 Ω B: Initial conduction resistance is 1.0 Ω or more and less than 2.0 Ω C: Initial conduction resistance is 2.0 Ω or more and less than 4.0 Ω D: Initial conductive resistance is 4.0Ω or more

[0079] [Table 1]

[0080] <Discussion of Results> The anisotropic conductive films as filler-containing films and the connection structures of Examples 1 to 3 showed results that were satisfactory for practical use in the evaluation items of immobility, indentation, and electrical conductivity.

[0081] (Reference examples 1~3) In addition, a filler-containing film of Reference Example 1 was prepared in which only the hole diameter of the through holes formed in the core film of Example 1 was changed to 3.60 μm, a filler-containing film of Reference Example 2 was prepared in which only the hole diameter of the through holes formed in the core film of Example 1 was changed to 3.40 μm, and a filler-containing film of Reference Example 3 was prepared in which only the thickness of the core film of Example 1 was changed to 3.40 μm.

[0082] The prepared filler-containing film was evaluated in the same manner as in Example 1. The filler-containing film of Reference Example 1 had the same indentation, but the conduction characteristics were rated D. The filler-containing film of Reference Example 2 had worse indentation and the conduction characteristics were also rated D. From the results of Reference Examples 1 and 2, it was inferred that when the diameter of the through-hole was not large enough, there was insufficient excess space for deformation when the filler was pressed in. The filler-containing film of Reference Example 3 also had the same results as Reference Example 2. It is inferred that the filler could not be pressed in sufficiently because the filler diameter and the film thickness were the same. [Industrial Applicability]

[0083] The filler-containing film of the present invention focuses on the relationship between "core film thickness", "filler diameter" and "through hole opening diameter", and limits these to a specific interrelationship. Therefore, when two components are joined via the filler-containing film by compression bonding, for example, thermocompression bonding, the resin flow of the core film is suppressed, unintended movement of the filler can be restricted, and good particle capture properties can be achieved. Moreover, when the filler-containing film is applied to a conductive film or anisotropic conductive film, good indentations can be obtained, and good conductivity can be achieved between connection electrodes. Therefore, the filler-containing film of the present invention is useful for connecting various electronic components to a substrate. [Explanation of symbols]

[0084] 1 Insulating base layer 2 Adhesive layer 3 Core Film 4. Filler 10. Filler-containing films 20 Peeling substrate th through hole P d Filler average particle size O d Through hole opening diameter C t Core Film Thickness

Claims

1. A filler-containing film in which a core film having through holes is sandwiched between an insulating base layer and an adhesive layer, and a filler is held in the through holes, The following equations (1) and (2): [Math 1] (In the formula, C ｔ is the thickness of the core film [μm], P ｄ is the average particle diameter of the filler [μm], O ｄ (This is the aperture diameter [μm] of the through-hole in the core film.) A filler-containing film that satisfies the requirements.

2. The following are equations (1') and (2') [Math 2] A filler-containing film according to claim 1 that satisfies the following conditions.

3. A filler-containing film according to claim 1 or 2, wherein the through holes are arranged in a regular pattern.

4. The filler-containing film according to claim 1, wherein the filler is conductive particles and is used as a conductive film or an anisotropic conductive film.

5. A joint in which a first member and a second member are joined together via the filler-containing film described in claim 1.

6. A connection structure comprising a filler-containing film according to claim 4, used as a conductive film or an anisotropic conductive film, wherein a first electronic component is electrically connected or anisotropically connected to a second electronic component.

7. A method for manufacturing a joined body, comprising joining a first member and a second member after placing a filler-containing film according to claim 1 between them.

8. A method for manufacturing a connection structure, comprising using the filler-containing film according to claim 4, used as a conductive film or an anisotropic conductive film, to electrically connect or anisotropically connect a first electronic component to a second electronic component.

9. A method for manufacturing a connection structure according to claim 8, wherein the terminals of a first electronic component and the terminals of a second electronic component are electrically connected with conductive particles.

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