Filler-containing film

Abstract

To provide a filler-containing film which suppresses resin flow of a core film and can restrict unintended movement of a filler, and prevents generation of pressure bonding unevenness when the film is pressure-bonded, for example, thermally pressure-bonded, when two members are joined to each other through the filler-containing film, by pressure bonding, for example, thermal pressure bonding.SOLUTION: There is provided a filler-containing film in which a core film having a through hole is sandwiched between an insulation base layer and an adhesive layer, and a filler is held on the through hole, wherein opening diameters (O1, O2) of a hole, a particle diameter Pd of the filler, layer thickness Ct of the core film, and a distance L between a center line X of the core film and a center line Y of the filler satisfy the following relation expression.SELECTED DRAWING: Figure 1B

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 unnecessary flow of the resin forming the filler-containing film 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 good conductivity is ensured by dispersing the conductive particles at a high density 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 may cause the conductive particles to move unnecessarily and be unevenly distributed between terminals, which may cause a short circuit, and it is therefore necessary to achieve both good conductivity and insulation.

[0003] In response to such demands, an anisotropic conductive film has been proposed in which conductive particles are filled into the pores of a porous film having pores arranged in a honeycomb pattern (Patent Document 5). In this anisotropic conductive film, the average pore diameter U L is the average pore size U M and the average pore size U L is set to 1.1 to 1.9 times the average particle diameter d of the conductive particles, and the average pore diameter U M is set to 0.1 to 1.0 times the average particle diameter d of the conductive particles. [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] JP 2019-114510 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the anisotropic conductive film of Patent Document 5, the average pore diameter U L Since the average particle diameter of the conductive particles is very large, 1.1 to 1.9 times, the retention of the conductive particles in the pores is reduced. Moreover, when the conductive particles are filled in the pores of the porous film, the position of the conductive particles in the depth direction is not considered at all. For this reason, the conductive particles may escape from the pores due to the resin flow of the binder resin that constitutes the porous film during anisotropic conductive connection, causing uneven distribution of the conductive particles. In addition, when the pressure is applied by a thermocompression tool during anisotropic conductive connection, the pressure application surface of the pressure application tool may tilt relative to the joining surface to be joined, resulting in uneven pressure application such as "one-sided contact," which is a concern, making it difficult to ensure both conductivity and insulation. Even when a filler-containing film is used as a conductive film, the occurrence of uneven pressure application such as "one-sided contact" may increase the difficulty and complexity of distinguishing between good and defective products.

[0006] Furthermore, in the anisotropic conductive film of Patent Document 5, the preferred porous film thickness is 5 μm to 50 μm, while the preferred conductive particle diameter is 2 μm to 3 μm. This means that the conductive particles may become completely embedded in the pores, and there is concern that the conductive particles may not be sufficiently crushed by the thermocompression bonding during anisotropic conductive connection, resulting in poor conductivity.

[0007] In addition, even in filler-containing films other than anisotropic conductive films, in which the holes of a porous film are filled with filler, if the filler escapes from the holes due to the resin flow of the binder resin that constitutes the porous film, the filler will become unevenly distributed rather than arranged as intended, and there is a concern that the intended optical, mechanical, or electrical properties of the filler-containing film will not be guaranteed.

[0008] 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, restrict unintended movement of the filler, and prevent uneven bonding during bonding, for example, thermocompression, when two components are joined by compression, 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 a filler is held in the through holes. [Means for solving the problem]

[0009] The inventors focused on "the relationship between the opening diameter of the through hole on the surface of the core film and the opening diameter of the through hole on the back surface," "the relationship between the opening diameter of the through hole on the surface of the core film and the filler diameter," and "the relationship between the core film thickness and the filler diameter," as well as "the ratio of misalignment of the conductive particles in the film thickness direction of the core film," and discovered that the above-mentioned objective could be achieved by limiting each of these to a specific relationship, thereby completing the present invention.

[0010] That is, the present invention provides a filler-containing film, comprising a core film having through holes sandwiched between an insulating base layer and an adhesive layer, and a filler held in the through holes, The present invention provides a filler-containing film that satisfies the following formulas (1) to (4).

[0011]

number

[0012] In the above formula, "O 1 " is the opening diameter of the through hole on the adhesive layer side surface of the core film, and "O 2 " is the opening diameter of the through hole on the insulating base layer side surface of the core film, and "C t " is the thickness of the core film, and "P d " is the average particle diameter of the filler, "L" is the distance between the center line X of the core film in the thickness direction of the film and the center line Y of the filler in the thickness direction of the film, and "S" is the average particle diameter P of the filler at the distance L. d This is the ratio [%] of the filler to the core film 3, in other words, the positional deviation ratio of the filler in the film thickness direction with respect to the core film 3. Note that the sign of "L" is positive toward the insulating base layer side. When conductive particles are used as the filler, this filler-containing film can be used as a conductive film or anisotropic conductive film.

[0013] 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 a 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, and a method for producing a connection structure in which the first member is conductively or anisotropically conductively connected to the second member by a 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

[0014] In the filler-containing film of the present invention, in addition to the "relationship between the opening diameter of the through hole on the front surface of the core film and the opening diameter of the through hole on the back surface," the "relationship between the opening diameter of the through hole on the front surface of the core film and the filler diameter," and the "relationship between the core film thickness and the filler diameter," the "positional deviation ratio of the conductive particles in the film thickness direction of the core film" is each limited to a specific range. Therefore, when two members are bonded via the filler-containing film by compression, for example, thermocompression, the resin flow of the core film can be suppressed, unintended movement of the filler can be restricted, and compression unevenness can be prevented from occurring during compression of the film, for example, thermocompression. [Brief description of the drawings]

[0015] [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

[0016] 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.

[0017] <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 (4).

[0018]

number

[0019] FIG. 1B is a partially enlarged cross-sectional view of the periphery of the filler 4 of the filler-containing film 10 of the present invention. As can be seen from FIG. 1B, in these formulas, “O 1 " is the opening diameter [μm] of the through hole th on the surface of the core film 3 on the adhesive layer 2 side, and "O 2 " is the opening diameter [μm] of the through hole th on the surface of the core film 3 on the insulating base layer 1 side, and "C t " is the thickness [μm] of the core film 3, and "P d " is the average particle diameter [μm] of the filler 4, and "L" is the distance [μm] between the center line X of the core film 3 and the center line Y of the filler 4 in the film thickness direction. "S" is the average particle diameter P d It is the ratio [%] of the thickness [μm], in other words, the positional deviation ratio [%] of the filler 4 with respect to the core film 3 in the film thickness direction. Note that the sign of "L" is positive and negative, with the positive sign being toward the insulating base layer side.

[0020] Below, we will explain the specific components of the filler-containing film 10 of the present invention, namely, "insulating base layer 1", "adhesive layer 2", "core film 3" and "filler 4", and then we will explain the parameter components that characterize the filler-containing film 10 of the present invention, namely, "Equation (1) showing the relationship between the opening diameter of the through hole on the front surface of the core film and the opening diameter of the through hole on the back surface", "Equation (2) showing the relationship between the opening diameter of the through hole on the front surface of the core film and the filler diameter", "Equation (3) showing the relationship between the core film thickness and the filler diameter", and "Equation (4) showing the positional deviation rate of the filler relative to the core film in the film thickness direction".

[0021] <Specific components> "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.

[0022] (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.

[0023] (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, particularly preferably 3000 Pa·s or more, and preferably 15000 Pa·s or less, more preferably 10000 Pa·s or less, particularly preferably 8000 Pa·s or less. The minimum 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, 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.

[0024] (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.

[0025] (Adhesive strength of insulating base layer 1) The insulating base layer 1 preferably has an adhesive strength that allows temporary bonding before compression to an article to which the filler-containing film is to be bonded, 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 insulating base layer 1 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.

[0026] The adhesive strength of the insulating base layer 1 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 insulating base layer 1 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 insulating base layer 1, it is possible to measure the adhesive strength between the glass plate being peeled off and the surface of the insulating base layer 1 bonded 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 This is the adhesive strength between the surface of the insulating base layer 1 in the direction of peeling and the article to be peeled off.

[0027] In addition, the adhesive strength of the insulating base layer 1 can also be determined by a test in which one end of a test piece is aligned and glued (pasted) and the other end is pulled up to peel off the test piece. 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.

[0028] 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.

[0029] "Adhesive layer 2" The adhesive layer 2 constituting the filler-containing film 10 of the present invention is a layer for temporarily pressing and attaching the filler-containing film 10 to an article. The adhesive layer 2 may be composed of a single insulating resin layer, or may be composed of a laminate of multiple insulating resin layers.

[0030] (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 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, as in the resin composition forming the adhesive 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 a core and the surface is coated with polyurethane.

[0031] (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 will be applicable to various uses. When used for anisotropic conductive connection, it is possible to more precisely suppress unnecessary movement of the filler (i.e., conductive particles).

[0032] (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 in order to fill the through holes of the core film with filler. If it is too thick, there is a concern that the resin will protrude when it is wound, so it is preferably 50 μm or less. In this way, the upper limit can be set appropriately according to the purpose.

[0033] (Adhesive strength of adhesive layer 2) The adhesive strength of the adhesive layer 2 is preferably such that it can be temporarily attached to an article to which the filler-containing film is to be thermocompression-bonded (it is sufficient that the adhesive strength is such that the film can be attached to the article). The adhesive strength of the 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 the adhesive strength 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.

[0034] Such adhesion can be adjusted by appropriately adjusting the resin composition constituting the adhesive layer 2 and by improving the smoothness of the adhesive layer 2 that forms the outer surface of the filler-containing film by the manufacturing method of the filler-containing film described below.

[0035] "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 the filler 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.

[0036] (Resin composition constituting core film 3) 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.

[0037] (Melt viscosity of core film 3) The melt viscosity of the core film 3 is preferably 1.1 times or more, more preferably 1.2 times or more, of the minimum melt viscosity of the insulating base layer 1 in the 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 compression bonded to an article, for example, by thermocompression bonding. The melt viscosity can be determined, for example, 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 at a temperature range of 30 to 250 ° C., a heating 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 as a melt viscosity adjuster, the adjustment conditions of the resin composition, etc.

[0038] (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.

[0039] (Through hole th 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. The opening preferably has a circular shape in plan view, but may have other shapes. In the present invention, the opening diameter O 1and the opening diameter O on the insulating base layer 1 side 2 It is preferable to set the opening diameter O on the insulating base layer 1 side to be approximately the same in order to simultaneously fill the through holes with the filler and push the filler into the through holes. 2 The opening diameter O on the adhesive layer 2 side 1 It is preferable that the concentration is 0.95 to 1.05 times, and more preferably 1.0 times.

[0040] 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 the 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 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 prevention 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).

[0041] 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 field of view of the film surface 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 through holes not filled with filler (residual rate) are 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% of the number of through holes th. This is because performing an elimination operation to bring the residual rate closer to zero may cause defects on the film surface.

[0042] The distance between the through holes th can be determined according to the objects to be connected and the purpose of use. The number 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.

[0043] 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 (Mitani Corporation) or Azo-kun (registered trademark) (Asahi Kasei Engineering Corporation)). The observation method and measurement technique are not limited to those described above.

[0044] In the present invention, the size of the through holes is unified, so that the effect of the invention can be more remarkable. For this purpose, 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, 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.

[0045] "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.), fillers containing a mixture of organic and inorganic materials (for example, particles having a resin core and a metal-plated surface (metal-coated resin particles)), conductive particles having insulating fine particles attached to the surface, conductive particles having an insulating surface, etc.) according to the performance required for the application, such as hardness and optical performance. For example, in optical films and matte films, silica filler, titanium oxide filler, styrene filler, acrylic filler, melamine filler, various titanates, and the like can be used. In films for capacitors, titanium oxide, magnesium titanate, zinc titanate, bismuth titanate, lanthanum oxide, etc. can be used. Fillers such as calcium titanate, strontium titanate, barium titanate, barium zirconate titanate, lead zirconate titanate, and mixtures thereof can be used. Adhesive films can contain polymer-based rubber particles, silicone rubber particles, and the like. Conductive films and anisotropic conductive films contain conductive particles. 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 by a known technique that does not impair the conductive characteristics.

[0046] (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 an 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 planar or cross-sectional images of the filler-containing film observed under a microscope. 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 particle size and shape analyzer FPIA-3000 (Malvern Panalytical). 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.

[0047] 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 an 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 anisotropic conductive connection between electronic components using an 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 anisotropic conductive connection will be easier, and the productivity of the connection process will be improved.

[0048] 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.

[0049] <Parameter components> As described above, the filler-containing film 10 of the present invention has the "relationship between the opening diameter of the through hole on the front surface of the core film and the opening diameter of the through hole on the back surface of the core film (formula (1))", the "relationship between the opening diameter of the through hole on the front surface of the core film and the filler diameter (formula (2))", the "relationship between the core film thickness and the filler diameter (formula (3))", and the "positional deviation ratio of the conductive particles in the film thickness direction of the core film (formula (4))" each limited to a specific range.

[0050]

number

[0051] 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, in these formulas, “O 1 " is the opening diameter [μm] of the through hole th on the surface of the core film 3 on the adhesive layer 2 side, and "O 2 " is the opening diameter [μm] of the through hole th on the surface of the core film 3 on the insulating base layer 1 side, and "C t " is the layer thickness [μm] of the core film 3, and "P d " is the average particle diameter [μm] of the filler 4, and "L" is the distance [μm] between the center line X of the core film 3 and the center line Y of the filler 4 in the film thickness direction. "S" is the average particle diameter P of the filler 4 at the distance L [μm]. d It is the ratio [%] of the thickness [μm], in other words, the positional deviation ratio [%] of the filler 4 with respect to the core film 3 in the film thickness direction. Note that the sign of "L" is positive and negative, with the positive sign being toward the insulating base layer side.

[0052] (Meaning of Formula (1)) Formula (1) is defined as "the opening diameter O of the through hole on the surface of the core film 3" 1 and the opening diameter O of the through hole on the back surface 2 The reason for focusing on this relationship is to make it easier to arrange the filler at a predetermined position in the through hole. In the present invention, the opening diameter O 2 The opening diameter O 1 Approximately the same size as the opening diameter O 1 The diameter of the opening on the back surface of the core film 3 is set to 0.95 to 1.05 times, preferably the same as the diameter of the opening on the back surface of the core film 3. 2 The surface opening diameter O 1 If the opening diameter is less than 0.95 times or more than 1.05 times, and becomes too small or too large relative to the opening diameter on the adhesive layer side surface, the degree of penetration of the adhesive layer and insulating base layer, which form the base of the hole, into the hole will change slightly, making it difficult to adjust.

[0053] (Meaning of formula (2)) Equation (2) is defined as the opening diameter O 1 The reason for focusing on this relationship is to make it easier for the filler to be filled in the through-holes and to be held in the holes. In the present invention, the opening diameter O 1 is the average particle size of the filler, P d The opening diameter O is set to 0.80 times or more, preferably 0.85 times or more, and 1.05 times or less, preferably 1.02 times or less. 1 is the average particle size of the filler, P d If the ratio is less than 0.80 times, the filler will be difficult to fill in the pores, and if the ratio is more than 1.05 times, the filler will tend to be difficult to retain in the pores.

[0054] (Meaning of formula (3)) Formula (3) is a formula showing the "relationship between the core film thickness and the filler diameter". The reason for focusing on this relationship is to make it easier for the filler to be filled in the through-holes and to be held in the holes, as described above. In the present invention, the core film thickness Ct , the average particle size P of filler 4 d The thickness of the core film C is set to 0.08 times or more, preferably 0.12 times or more, and 0.40 times or less, preferably 0.36 times or less. t is the average particle size of the filler, P d If the thickness is less than 0.08 times, the film thickness will be difficult to retain the filler, and the filler will tend to come out easily, whereas if the thickness is more than 0.40 times, the pore size will be too small to press in.

[0055] (Meaning of formula (4)) Equation (4) shows the "positional displacement ratio S of the filler in the film thickness direction of the core film." The reason for focusing on this relationship is that since the indentation load from the tool is applied evenly to the entire film, in the present invention where the film thickness is smaller than the filler diameter, many fillers are simultaneously subjected to the load during the load application process. In the present invention, the average particle diameter P of filler 4 at the distance L [μm] between the center line X of core film 3 and the center line Y of filler 4 in the film thickness direction is d The ratio S [%] to [μm] is set to 20% or less, preferably 15% or less. This is because if the ratio S exceeds 20%, the load applied to the filler tends to become uneven, and there is a concern that defects such as the filler coming out during pressing may occur.

[0056] <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).

[0057] 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).

[0058] 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).

[0059] Finally, the adhesive layer-forming composition 2' is applied onto the core film 3 (FIG. 2E), pressed with a pressure-bonding tool as necessary, and then dried by a conventional method to form the adhesive layer 2 (FIG. 2F). This makes it possible to obtain a filler-containing film having a release substrate 20, and by removing the release substrate 20, the filler-containing film 10 shown in FIG. 1A can be obtained.

[0060] <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.

[0061] 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 μm 2 ~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, the filler-containing film may be used as a conductive film or anisotropic conductive film, or may be used as a spacer film using the filler as a spacer.

[0062] The conductive film or anisotropic conductive film of the present invention may be used to stack IC chips or wafers to form a multilayer structure. The electronic components connected with the conductive film or anisotropic conductive film of the present invention are not limited to the above-mentioned examples of electronic components. The conductive film or anisotropic conductive film of the present invention can be used for various electronic components that have become more diverse in recent years. The present invention includes a film attachment body in which the filler-containing film of the present invention is attached to various articles, and particularly includes a connection body in which a first electronic component and a second electronic component are connected via an anisotropic conductive film.

[0063] 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.

[0064] When the filler-containing film is configured as, for example, a conductive film or anisotropic conductive film, a more specific method of use is, for example, when the first electronic component is an IC chip and the second electronic component is a substrate, generally placing the first electronic component on the pressure tool side and the second electronic component on a stage facing the first electronic component, attaching a conductive film or anisotropic conductive film to the second electronic component in advance, and using the pressure tool to perform compression bonding, for example thermocompression bonding, of the first electronic component and the second electronic component. In this case, the 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.

[0065] 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 to the electronic component, and the unnecessary movement of the conductive particles can be suppressed. Specifically, when the temporary pressure bonding is performed by attaching one electronic component to be connected to one surface of the conductive film or the anisotropic conductive film and attaching the other electronic component to the other surface 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 during the main pressure bonding as well as pressing during the temporary pressure bonding is performed 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 case of the conductive film or the present invention, making such a connection by two-stage pressing makes it possible to significantly reduce unnecessary movement of the conductive particles during compression bonding, for example during thermocompression bonding. EXAMPLES

[0066] The present invention will be described in detail below with reference to Examples and Comparative 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 and Comparative Examples are shown below.

[0067] <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

[0068] <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

[0069] <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

[0070] Examples 1 to 4, Comparative Examples 1 to 3 The above-mentioned resin composition for forming an insulating base layer was applied to a release film (50 μm thick) made of polyethylene terephthalate with a release treatment applied to the surface, and dried by conventional methods to form an insulating base layer film with a layer thickness (3.0 μm).

[0071] Next, a mold substantially similar to the mold described in paragraph 0111 of Japanese Patent No. 6187665 was prepared using transparent polycarbonate pellets on a polyethylene terephthalate release film (50 μm thick) with a release treatment applied to the surface. A coating liquid (diluted with a general-purpose solvent to a solid content of 20%) prepared from the mixture of the resin compositions for forming the core film described above was applied to this mold, and the mold was left to dry in a 60° C. dryer for 5 minutes to obtain a surface opening diameter (O 1 ) and the back opening diameter (O 2 A core film having through holes th with a diameter of 1 mm and a thickness of 1 mm was obtained. 1 ) is the rear opening diameter (O 2 ) was formed (Comparative Examples 1 to 4).

[0072] Next, the core film with the through holes formed therein was peeled off from the release film, and the core film was laminated from the back side onto the insulating base layer film prepared previously (FIG. 2C).

[0073] Next, the filler was sprayed onto the core film, and the filler with the average particle size Pd [μm] in Table 1 was used to fill the through-holes using a squeegee, and any filler that was not filled into the through-holes was removed with an air blower (Figure 2D).

[0074] Finally, the adhesive layer-forming resin composition was applied onto the core film so that the total thickness of the filler-containing film was about 18 μm (FIG. 2E), dried by a conventional method, and pressed with a pressure-bonding tool to form an adhesive layer 2 (FIG. 2F). This resulted in a filler-containing film with a release film on the surface of the insulating base layer. By removing the release film, the filler-containing film shown in FIG. 1A can be obtained. The distance L [μm] between the center line of the core film and the center line of the filler in the thickness direction of the filler-containing film was measured with an optical microscope, and the results are shown in Table 1. Furthermore, the positional deviation ratio S [%] of the filler relative to the core film in the thickness direction of the filler-containing film was calculated, and the results are shown in Table 1.

[0075] <Evaluation> The obtained filler-containing film was tested and evaluated for the "immobility" of the filler, the "uneven compression bonding" in the filler-containing film, and the "conductivity" when the filler-containing film was used as an anisotropic conductive film, as described below.

[0076] (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 pressurized (180° C., 60 MPa, 5 seconds) to create a connection structure for evaluation. In this connection structure, the number of fillers captured was measured for 100 pieces in a 6 μm×66.6 μm area where the bumps of the evaluation IC and the terminals of the glass substrate overlap, the minimum number of captures was obtained, and the result was evaluated according to the following particle capture property evaluation criteria. The obtained results are shown in Table 1. In practical use, it is desirable to have an A or B rating.

[0077] 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

[0078] 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

[0079] (Uneven pressure bonding) The appearance of the core film with through holes in the space between the terminals after crimping was observed, and the deformation was so great that the filler came out of the through hole, which was regarded as crimping unevenness. The space between the terminals was observed at 10 points to check for the presence or absence of crimping unevenness. From a practical standpoint, a rating of C is acceptable, but a rating of B or higher is preferable.

[0080] Criteria for evaluating uneven pressure bonding A: The filler has not come out of the through hole. B: Filler has fallen out of the through holes in 2 or less out of 10 places C: Filler has fallen out of the through holes in 5 or less out of 10 places D: Filler has fallen out of the through holes in 6 or more of 10 places.

[0081] (conductivity) The anisotropic conductive film as the filler-containing film of each Example and Comparative 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 initial conductive resistance is required to be rated A or B.

[0082] 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.

[0083] Conduction characteristic evaluation IC External size 1.8×20.0mm Thickness: 0.5mm Bump specifications: Width 30μm x length 85μm, distance between bumps 50μm, bump height 15μm

[0084] Glass substrate (Ti / Al wiring) Glass material: Corning 1737F External size 30×50mm Thickness: 0.5mm

[0085] Continuity evaluation 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

[0086] [Table 1]

[0087] <Discussion of Results> The anisotropic conductive films as filler-containing films of Examples 1 to 4 satisfied the formulas (1) to (4), and therefore were rated A or B for all the evaluation items. In particular, in the cases of Examples 2 and 3, in which the thickness of the core film was about 1.0 μm, all the evaluation items were rated A.

[0088] In contrast, in the case of Comparative Example 1, which does not satisfy all of the formulas (1) to (4), All evaluation items were rated C. In addition, in the case of Comparative Examples 2 and 3, which satisfied formulas (3) and (4) but did not satisfy formulas (1) and (2), the conductivity was rated A, but the immobility and compression unevenness were rated C. [Industrial Applicability]

[0089] In the filler-containing film of the present invention, in addition to the "relationship between the opening diameter of the through hole on the front surface of the core film and the opening diameter of the through hole on the back surface," the "relationship between the opening diameter of the through hole on the front surface of the core film and the filler diameter," and the "relationship between the thickness of the core film and the filler diameter," the "positional deviation ratio of the conductive particles in the film thickness direction of the core film" is limited to a specific range. Therefore, when two members are bonded through the filler-containing film by compression bonding, for example, thermocompression bonding, the resin flow of the core film can be suppressed, unintended movement of the filler can be restricted, and compression bonding unevenness can be prevented from occurring during compression bonding of the film, for example, thermocompression bonding. Therefore, the filler-containing film of the present invention is useful when connecting various electronic components to a substrate. [Explanation of symbols]

[0090] 1. Insulating base layer 1' Insulating base layer forming composition 2 Adhesive layer 2′ Adhesive layer forming composition 3 Core Film 4. Filler 10. Filler-containing films 20 Peeling substrate th through hole P d Filler average particle size O 1 Opening diameter of through hole on adhesive layer side surface of core film O 2 Opening diameter of through hole on the surface of the core film facing the insulating base layer C t Core film thickness X: Center line of the core film in the film thickness direction Y Center line of the filler in the film thickness direction L is the distance between the centerline X of the core film and the centerline Y of the filler

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) to (4): (In the formula, "O １ " is the aperture diameter [μm] of the through-hole on the adhesive layer side surface of the core film, and "O ２ " is the aperture diameter [μm] of the through hole on the insulating base layer side surface of the core film, and "C ｔ " is the thickness of the core film [μm], and "P ｄ " is the average particle diameter of the filler [μm], "L" is the distance [μm] between the center line X of the core film and the center line Y of the filler in the film thickness direction, and "S" is the average particle diameter P of the filler at a distance L [μm]. ｄ This is a percentage [%] relative to [μm]. Note that the positive / negative sign of "L" is considered positive towards the insulating base layer. A filler-containing film that satisfies the requirements.

2. O １ = O 2 The filler-containing film according to claim 1.

3. Average particle size P of filler ｄ The filler-containing film according to claim 1 or 2, wherein the filler is 1 to 200 μm thick.

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

5. A filler-containing film according to claim 1 or 2, wherein the filler is conductive particles and is used as a conductive film or an anisotropic conductive film.

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

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 connection structure comprising a filler-containing film according to claim 5, 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.

9. A method for manufacturing a connection structure, comprising using the filler-containing film according to claim 5, 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.

10. A method for manufacturing a connection structure according to claim 9, 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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