Filler-containing film, bonded body, and method for producing same

Abstract

A filler-containing film in which a core film having a through-hole is sandwiched between an insulating base layer and an adhesive layer and a filler is held in the through-hole, the filler-containing film being capable of suppressing the flow of resin in the core film, restricting unnecessary movement of the filler, and suppressing the occurrence of uneven crimping when two members are bonded by crimping via the filler-containing film. The filler-containing film satisfies formula (1) Ct < = 0.8 Pd, formula (2) 1.2 Pd < = Od, and formula (3) Eplt, and the filler is uniformly flattened over the entire surface of the crimping portion of the film. Ef. In the formulae, Ct is the layer thickness of the core film, Pd is the average particle diameter of the filler, Od is the opening diameter of the through hole of the core film, Ef is the compressive modulus of elasticity of the core film, and Ep is the 30% compressive modulus of elasticity of the filler.

Description

Technical Field

[0001] The present invention relates to filled films. Background Art

[0002] Filler-containing films in which fillers are dispersed in a resin layer are used for a variety of applications, such as matte films, capacitor films, optical films, label films, antistatic films, conductive films, and anisotropic conductive films (Patent Documents 1, 2, 3, and 4). When a filler-containing film is used by thermocompression bonding on an article, it is desirable to suppress unnecessary flow of the resin forming the filler-containing film during thermocompression bonding and to suppress uneven distribution of the filler from the perspective of optical, mechanical, or electrical properties. In particular, when conductive particles are contained as fillers and the filler-containing film is used as a conductive film or anisotropic conductive film for mounting electronic components, if the conductive particles are dispersed at a high density in the insulating resin layer so that high-density mounting of electronic components can be accommodated, the conductive particles will move unnecessarily and be unevenly distributed between the terminals due to excessive resin flow during mounting of the electronic components, which is a major cause of short circuits. Therefore, it is desirable to suppress such excessive resin flow.

[0003] In response to such a demand, an anisotropic conductive film has been proposed, which is obtained by laminating an insulating film with through holes on an adhesive layer, filling the through holes with conductive particles, and then laminating another adhesive layer (Patent Document 5). In order to suppress excessive resin flow of the insulating film during anisotropic conductive connection, the thickness of the insulating film is set to be 0.4 times or more and 1.0 times or less of the diameter of the conductive particles, and the insulating film is further increased to 1.0 times or less per 1 mm. 2 The number of conductive particles is set to be not less than 0.9 times and not more than 1.0 times the number of through holes.

[0004] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Laid-Open No. 2006-15680 Patent Document 2: Japanese Patent Application Laid-Open No. 2015-138904 Patent Document 3: Japanese Patent Application Laid-Open No. 2013-103368 Patent Document 4: Japanese Patent Application Laid-Open No. 2014-183266 Patent Document 5: Japanese Patent Application Publication No. 2018-174069. Summary of the Invention

[0005] Problems to be solved by the invention However, in the anisotropic conductive film of Patent Document 5, as a factor for suppressing excessive resin flow of the insulating film, factors other than the "relationship between the thickness of the insulating film and the diameter of the conductive particles" and the "relationship between the density of the conductive particles and the density of the through-holes" are not fully considered. Therefore, during anisotropic conductive connection, the excessive resin flow of the insulating film cannot be fully suppressed, which will lead to unnecessary movement of the conductive particles. In addition, when a flat connected surface is crimped with a crimping (preferably hot crimping) tool having a flat crimping surface, there is a concern that "partial contact" (the crimping surface of the crimping tool is crimped at an angle relative to the connected surface) will cause uneven crimping. If such uneven crimping occurs, it becomes difficult to evenly flatten the conductive particles on the entire surface of the film crimping portion, which may reduce the conduction reliability. The same problem is also concerned when two components are joined by crimping (e.g., hot crimping) by sandwiching a core film having through-holes between an insulating base layer and an adhesive layer and a filler-containing film having fillers in the through-holes.

[0006] The purpose of the present invention is to solve the problems of the above-mentioned prior art, that is, when two components are joined by crimping (such as hot crimping, etc.) by clamping a core film having through holes between an insulating base layer and an adhesive layer and a filler-containing film in which fillers are retained in the through holes, the flow of resin can be suppressed and unnecessary movement of the filler can be restricted. In addition, the occurrence of uneven crimping can be suppressed, and the filler can be evenly flattened on the entire surface of the crimped portion of the film.

[0007] Means used to solve problems The inventors focused on the "relationship between the core film thickness and the filler diameter", "the relationship between the filler diameter and the through-hole opening diameter", and "the relationship between the compressive elastic modulus of the core film and the compressive elastic modulus of the filler", and found that by limiting each of them to a specific relationship, the above-mentioned objectives can be achieved, thereby completing the present invention.

[0008] Specifically, 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 fillers are retained in the through-holes. The filler-containing film satisfies the following formulas (1) to (3).

[0009] C t ≤0.8P d (1) 1.2P d ≤O d (2) E p <E f (3) In the above formulas (1) to (3), C t is the thickness of the core film, P d is the average particle size of the filler, O d is the opening diameter of the through hole of the core membrane, Ef is the compressive elastic modulus of the core membrane, E p It is the 30% compressive elastic modulus of the filler. In the case where conductive particles are used as the filler, the filler-containing film can be used as a conductive film or an anisotropic conductive film.

[0010] The present invention also provides a joined body in which a first component and a second component are joined via the filler-containing film of the present invention. Preferably, the present invention provides a connected structure in which a first electronic component is conductively connected or anisotropically conductively connected to a second electronic component via the filler-containing film serving as a conductive film or an anisotropic conductive film. Furthermore, the present invention provides a method for producing a joined body, wherein the filler-containing film is similarly disposed between the first and second components and then joined. Preferably, the present invention provides a method for producing a connected structure in which the filler-containing film serving as a conductive film or an anisotropic conductive film serves as the conductive film or an anisotropic conductive film to electrically connect the first electronic component or anisotropically conductively connected to the second electronic component. In this manufacturing method, preferably, the terminals of the first electronic component and the terminals of the second electronic component are electrically connected via conductive particles.

[0011] Effects of the Invention In the filler-containing film of the present invention, the relationships between the core film thickness and filler diameter, the filler diameter and through-hole opening diameter, and the compressive modulus of the core film and the filler are each defined to specific relationships. Consequently, when two components are joined by compression (e.g., thermocompression) via the filler-containing film, resin flow in the core film is suppressed, limiting unintended filler movement. Furthermore, uneven compression is suppressed, allowing the filler to be evenly compressed across the entire surface of the film at the compression point. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] [ Figure 1A ] Figure 1A 2 is a cross-sectional view of a filler-containing membrane according to the present invention.

[0013] [ Figure 1B ] Figure 1B for Figure 1A A partially enlarged cross-sectional view of a filler-containing membrane.

[0014] [ Figure 2A ] Figure 2A This is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0015] [ Figure 2B ] Figure 2B This is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0016] [ Figure 2C ] Figure 2C This is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0017] [ Figure 2D ] Figure 2D This is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0018] [ Figure 2E ] Figure 2E This is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0019] [ Figure 2F ] Figure 2F This is an explanatory diagram of the method for producing the filler-containing film of the present invention. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of the filler-containing film of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in each of the drawings, the same reference numerals represent the same or equivalent components.

[0021] <Overall Structure of Filler-Containing Film 1A> Figure 1A : is a cross-sectional view of a filler-containing film 10 of the present invention. The filler-containing film 10 is characterized by having a structure in which a core film 3 having a through-hole th is sandwiched between an insulating base layer 1 and an adhesive layer 2, and a filler 4 is retained in the through-hole th, satisfying the following formulas (1) to (3), preferably formulas (1') to (3').

[0022] C t ≤0.8P d (1) 1.2P d ≤O d (2) E p <E f (3) 0.5P d ≤C t ≤0.8P d (1') 1.2P d ≤O d <1.5P d (2') E p <E f <1.2E p (3') In these formulas, as shown in the partially enlarged cross-sectional view of the periphery of the filler 4 of the filler-containing film 10 of the present invention, Figure 1B It is known that C t is the thickness of the core film [μm], P d represents the average particle size of the filler [μm], O d represents the opening diameter of the through-hole of the core film [μm]. f is the compressive elastic modulus of the core membrane [MPa], E PIndicates the 30% compressive elastic modulus of the filler [MPa]. Here, the compressive elastic modulus E of the core film is f and the 30% compression elastic modulus E of the filler P It can be measured by a known method. For the core film, if it is monolithicized into a measurable size by a known method, it can be measured according to the filler measurement method. Therefore, as described later, it can be measured at room temperature (23°C ± 15°C) using a micro compression tester (manufactured by FISCHER, Fischerscope H-100). Specifically, a single piece of the core film is compressed in the thickness direction, and the hardness when the thickness is reduced by 30% (compression hardness at 30% compression deformation (K value [MPa])) can be measured. The obtained K value is a value calculated by the following formula. The smaller the K value, the softer the film can be evaluated.

[0023] In the above formula, "F" is the load of the core film at 30% compression deformation [N], "S" is the displacement at 30% compression deformation [mm], and "R" is the thickness of the core film before compression [mm].

[0024] <Insulating Base Layer> The insulating base layer 1 constituting the filler-containing film 10 of the present invention serves as a base layer during the production of the filler-containing film 10 and is used to form the core film 3 thereon. Such an insulating base layer 1 may be composed of a single insulating resin layer or a laminate of multiple insulating resin layers. Furthermore, the insulating base layer 1 preferably exhibits adhesiveness.

[0025] (Resin composition constituting insulating base layer) The resin composition constituting the insulating base layer 1 is appropriately selected according to the purpose of the filler-containing film. For example, a thermoplastic resin composition, a high-viscosity adhesive resin composition, or a curable resin composition can be cited. For example, when the filler-containing film is used as a conductive film or an anisotropic conductive film, a curable resin composition formed by a polymerizable compound and a polymerization initiator can be used, similar to the resin composition for forming the insulating resin layer of the existing conductive film or anisotropic conductive film. In this case, as the polymerization initiator, a thermal polymerization initiator can be used, a photopolymerization initiator can be used, or a combination of these can be used. For example, a thermal cationic polymerization initiator can be used as the thermal polymerization initiator, an epoxy resin can be used as the thermal polymerizable compound, a light free radical polymerization initiator can be used as the photopolymerization initiator, and an acrylate compound can be used as the photopolymerizable compound. As the thermal polymerization initiator, a thermal anionic polymerization initiator can also be used. As the thermal anionic polymerization initiator, it is preferred to use a microcapsule-type latent curing agent with an imidazole modified body as the core and its surface coated with polyurethane.

[0026] (Minimum Melt Viscosity of Insulating Base Layer 1) In order to suppress unnecessary movement of the filler 4 due to resin flow when the filler-containing film 10 is press-bonded (e.g., thermocompression-bonded) to an article and to guide appropriate resin flow, the minimum melt viscosity of the insulating base layer 1 can be 200 Pa·s or higher, preferably 1500 Pa·s or higher, more preferably 2000 Pa·s or higher, and even more preferably 3000 Pa·s or higher, preferably 15000 Pa·s or lower, more preferably 10000 Pa·s or lower, and particularly preferably 8000 Pa·s or lower. As an example, the minimum melt viscosity can be determined using a rotational rheometer (manufactured by TA Instruments) with a constant measurement pressure of 5 g and a measuring plate having a diameter of 8 mm. More specifically, it can be determined by setting the temperature range to 30-200°C, a heating rate of 10°C / min, a measurement frequency of 10 Hz, and a load variation of 5 g on the measuring plate. It should be noted that the minimum melt viscosity can be adjusted by changing the type and amount of the fine solids used as the melt viscosity modifier, the adjustment conditions of the resin composition, etc.

[0027] (Thickness of insulating base layer 1) In order to stably hold the core film 3 and the filler 4, etc., the thickness of the insulating base layer 1 is 1 / 2 of the average particle size P of the filler 4. d The upper limit of the thickness of the insulating base layer 1 is preferably 0.6 times or more, more preferably 1.2 times or more, and particularly preferably 1.5 times or more. Furthermore, in order to prevent unnecessary movement of the filler 4 due to resin flow, the upper limit of the thickness of the insulating base layer 1 is preferably 10 times or less, and more preferably 5 times or less, the average particle size of the filler 4. The layer thickness can be measured using a known thickness gauge or film thickness measuring instrument.

[0028] (Adhesion of insulating base layer 1) The insulating base layer 1 preferably has an adhesive force that can be temporarily pressed before pressing an article containing a filler film to be pressed (for example, hot pressing). The adhesive force can be measured in accordance with JIS Z 0237. Alternatively, it can be measured as tack force by a probe method in accordance with JIS Z 3284-3 or ASTM D2979-01. The adhesive force of the adhesive layer 2 constituting the filler film 10 obtained by the probe method is preferably 1.0 kPa (0.1 N / cm2) when measured, for example, at a probe pressing speed of 30 mm / min, a pressure of 196.25 gf, a pressing time of 1.0 second, a peeling speed of 120 mm / min, and a measuring 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 )above.

[0029] It should be noted that the adhesion of the filler-containing film can also be determined according to the bonding strength test described in Japanese Patent Application Publication No. 2017-48358. In this bonding strength test, for example, when the filler-containing film 10 is clamped between two glass plates, one of the glass plates 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, the adhesion between the fixed glass plate and the filler-containing film is enhanced, so that the adhesion between the peeled glass plate and the surface of the filler-containing film bonded to the glass plate can be measured. The bonding strength (adhesion) measured in this way can preferably be set to 1 N / cm 2 (10 kPa) or more, more preferably 10 N / cm 2 (100 kPa) or more. This becomes the adhesive force between the surface of the filler-containing film 10 located in the peeling direction and the peeled object.

[0030] Alternatively, the adhesive strength of a filler-containing film can be determined by aligning one end of a test piece and bonding (laminating) the test piece and then lifting the other end to peel the test piece. The adhesive strength measured by this test method can be equivalent to that in the above-mentioned adhesive strength test (1 N / cm 2 (10 kPa) or more). If the adhesive strength obtained by the above-mentioned adhesive strength test is large enough (for example, 10N / cm 2 (100 kPa) or more), the adhesive strength obtained by this test method may be 10% or more of the adhesive strength obtained by the above-mentioned adhesive strength test.

[0031] Such adhesiveness can be adjusted by appropriately adjusting the resin composition constituting the insulating base layer and improving the smoothness of the insulating base layer forming the outer surface of the filler-containing film by the method for producing the filler-containing film described below.

[0032] <Adhesive layer 2> The adhesive layer 2 constituting the filler-containing film 10 of the present invention is a layer for temporarily pressing the filler-containing film 10 onto an article. Such an adhesive layer 2 may be composed of a single insulating resin layer or a laminate of a plurality of insulating resin layers.

[0033] (Resin Composition Constituting Adhesive Layer 2) The resin composition constituting the adhesive layer 2 is the same as the insulating base layer 1, and is appropriately selected according to the purpose of the filler film. For example, a thermoplastic resin composition, a high-viscosity adhesive resin composition or a curable resin composition can be cited. For example, when the filler film is used as a conductive film or an anisotropic conductive film, the curable resin composition formed by a polymerizable compound and a polymerization initiator can be used, as is the resin composition forming the adhesive layer of an existing conductive film or an anisotropic conductive film. In this case, as the polymerization initiator, a thermal polymerization initiator can be used, a photopolymerization initiator can be used, or both can be used. For example, a thermal cationic polymerization initiator can be used as a thermal polymerization initiator, an epoxy resin can be used as a thermal polymerizable compound, a light free radical polymerization initiator can be used as a photopolymerization initiator, and an acrylate compound can be used as a photopolymerizable compound. As a thermal polymerization initiator, a thermal anionic polymerization initiator can also be used. As a thermal anionic polymerization initiator, it is preferred to use a microcapsule type latent curing agent formed by coating its surface with polyurethane using an imidazole modified body as a core.

[0034] (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. It may also 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, the flow of the resin when the filler-containing film 10 is pressed (e.g., hot-pressed) onto an article can be precisely controlled, and it can be expected to be applied to various purposes. When used for conductive connection, especially anisotropic conductive connection, the minimum melt viscosity of the adhesive layer is preferably lower than the minimum melt viscosity of the insulating base layer. The unnecessary movement of the conductive particles as fillers can be suppressed more precisely.

[0035] (Thickness of Adhesive Layer 2) The thickness of the adhesive layer 2 can be the same as that of the insulating base layer 1. It can also be intentionally set lower or higher than that of 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 preferably thinner. For filling, it can also be set to 20 μm or more. If it is too thick, there is a concern about resin extrusion when it is made into a package, so it is preferably 50 μm or less. Thus, the upper limit can be appropriately set according to the purpose.

[0036] (Adhesion of Adhesive Layer 2) The adhesive layer 2 preferably has sufficient adhesion to temporarily adhere to an article to which the filler film is to be bonded (e.g., thermally bonded) (suffice it to provide sufficient adhesion to adhere to the article). The adhesive layer 2 may have the same adhesion as the insulating base layer 1, may be stronger than the insulating base layer 1, or may be weaker. The adhesive strength of the adhesive layer 2 and the insulating base layer 1 may be optimized, respectively, depending on whether the surface to be bonded to the article is the insulating base layer 1 or the adhesive layer 2, and the degree of adhesion required for the article to be bonded.

[0037] Such adhesiveness can be adjusted by appropriately adjusting the resin composition constituting the adhesive layer 2 and improving the smoothness of the adhesive layer 2 forming the outer surface of the filler-containing film by the method for producing the filler-containing film described below.

[0038] <Core Film 3> The core film 3 constituting the filler-containing film 10 of the present invention has through-holes th for filling the filler 4. This layer serves as a spacer for suppressing unintended movement of the filler 4 caused by resin flow in the insulating base layer 1 or adhesive layer 2. Such a core film 3 may be composed of a single insulating resin layer or a laminate of multiple insulating resin layers.

[0039] (Resin Composition Constituting Core Film 3) The resin composition constituting the core film 3 is appropriately selected according to the purpose of the filler-containing film 10. For example, thermoplastic resin compositions or high-viscosity adhesive resin compositions containing phenoxy resins, polyimide resins, polyamide resins, polyacetal resins, polycarbonate resins, polyethylene resins, polypropylene resins, polystyrene resins, polyvinyl chloride resins, polyvinyl acetate resins, etc., or curable resin compositions containing epoxy resins, acrylic resins, etc. or mixtures thereof can be listed.

[0040] (Melt viscosity of core film 3) In order to suppress the unnecessary movement of the filler 4 caused by the flow of the resin when the filler-containing film 10 is pressed (e.g., hot pressing) on ​​the article, the melt viscosity of the core film 3 is 1.1 times, more preferably 1.2 times or more, the lowest melt viscosity of the viscosity of the insulating base layer 1 in the temperature range during pressing (e.g., hot pressing). As an example, the melt viscosity can be obtained using a rotational rheometer (manufactured by TA Instruments) with a measuring pressure kept constant at 5 g and a measuring plate with a diameter of 8 mm. More specifically, it can be obtained by setting the temperature range to 30~250°C, a heating rate of 10°C / min, a measuring frequency of 10 Hz, and a load change of 5 g on the above-mentioned measuring plate. It should be noted that the adjustment of the melt viscosity can be carried out by changing the type or amount of the micro-solids used as the melt viscosity adjuster, the adjustment conditions of the resin composition, etc.

[0041] (Thickness of core film 3) In order to stably hold the filler 4, the thickness of the core film 3 is determined by the average particle size P of the filler 4. d This will be described later.

[0042] (Through hole of core film 3) A through hole th for filling and holding the filler 4 is formed in the core film 3. The through hole th is open on the adhesive layer 2 side and the insulating base layer 1 side respectively. The top view shape of the opening is preferably circular, but it can also be other shapes. Usually, the opening diameter on the adhesive layer 2 side and the opening diameter on the insulating base layer 1 side can be the same, or a taper can be set in the through hole. For example, the opening diameter on the adhesive layer 2 side can be made larger than the opening diameter on the insulating base layer 1 side. In other words, the through hole th has a taper in a manner that widens from the insulating base layer 1 side to the adhesive layer 2 side. By setting the taper, the filler 4 can be made difficult to move. The degree of taper can be determined according to the melt viscosity, layer thickness and type of connection object of the adhesive layer 2 and the insulating base layer 1.

[0043] Such through holes th can be arranged in a random pattern in the core film 3, or they can be arranged in a regular pattern. Such a through hole pattern is essentially synonymous with the presence pattern of the filler in the filler-containing film 10. As examples of regular patterns, lattice arrangements such as square lattices, rectangular lattices, and rhombus lattices can be cited. It is also possible to combine multiple lattices of different shapes. By being a regular pattern, the advantage of easy quality management can be cited. It is also possible to arrange the through holes th in a straight line at a prescribed interval and arrange the through holes in parallel at a prescribed interval. It is also possible to repeat the areas where the through holes th are densely arranged and the areas where the through holes th are sparsely arranged regularly. In the case of using the filler-containing film as a conductive film or an anisotropic conductive film, a regular arrangement of through holes isolated from each other is formed, which is more preferred because it takes into account the capture stability and short circuit suppression at the terminal. It should be noted that whether the through holes th are regularly arranged can be distinguished by, for example, observing whether the prescribed arrangement of the through holes or fillers is repeated in the long side direction of the film (the winding direction when the filler-containing film is made into a roll).

[0044] In addition, the filler filling rate into the through-holes can be calculated as {(the number of fillers / the number of through-holes) × 100 (%)}. This is the same as the number density described below, and can be calculated by observing the field of view of the membrane surface. The filler filling rate can be 95% or more, preferably 98% or more, and more preferably 99.5% or more. It is desirable that the residual filler (residual rate) that is not filled into the through-holes is small (close to zero), but in practice, it can be a residual rate of 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 the exclusion operation is performed in a manner that makes the residual rate close to zero, it may become a reason for damage to the membrane surface.

[0045] The distance between through holes th can be determined according to the connected items or applications. In addition, the number density of through holes th is usually 10 / mm. 2 Above, preferably 30 / mm 2 Above, the upper limit is 500,000 pieces / mm 2 Below, preferably 250,000 pieces / mm 2 Below, more preferably 100,000 pieces / mm 2 The number density can be measured by microscopic observation with a film surface field of view. The preferred observation area during microscopic observation is 2 mm. 2 Above, preferably 10mm 2 above.

[0046] The number density of through-holes th (i.e., fillers) can be determined not only by observation using a metallographic microscope but also by measuring and observing images using image analysis software (e.g., WinROOF (manufactured by Mitani Shoji Co., Ltd.) or A-Image-kun (registered trademark) (manufactured by Asahi Kasei Engineering Corporation). The observation and measurement methods are not limited to those described above.

[0047] In the present invention, the effect of the invention can be more significantly exerted by unifying the size of the through-holes. To this end, it is desirable that the size and depth of the opening of the through-holes meet the following conditions. That is, in the filler-containing film, the total observation area is 1 mm 2 More than, preferably 2mm 2 When the number of through holes is more than 1000 (preferably more than 2000), it is desirable that the size and depth of the openings of more than 95%, preferably more than 98%, and more preferably more than 99.5% of the through holes in the region with more than 1000 through holes are consistent. Here, the "consistent" in "consistent size and depth of the openings" means that, taking into account measurement errors, the size and depth of the opening of a certain through hole are within the range of ±15%, preferably within ±10%, and more preferably within ±5% of the average size and average depth of the openings of the through holes contained in the specified region. It should be noted that since there are through holes with different shapes of openings, the size of the opening can be set as the diameter when the area of ​​the opening is converted into a circle.

[0048] <Padding 4> As filler 4 in the present invention, it can be appropriately selected from among known inorganic fillers (metal particles, metal oxide particles, metal nitride particles, etc.), organic fillers (resin particles, rubber particles, etc.), fillers mixed with organic and inorganic materials (for example, particles whose core is formed of a resin material and whose surface is plated with metal (metal-coated resin particles), fillers with insulating particles attached to the surface of conductive particles, fillers with insulating treatment on the surface of conductive particles, etc.), according to the performance required for the application such as hardness and optical properties. From those whose 30% compressive elastic modulus of the filler can be measured. For example, in optical films or matte films, resin fillers such as styrene fillers and acrylic fillers can be used. The adhesive film can contain polymer rubber particles, silicone rubber particles, etc. Conductive particles are contained in the conductive film or the anisotropic conductive film. As conductive particles, metal particles or alloy particles can be used, but metal-coated resin particles are preferred, and metal-coated resin particles with insulating particles attached to the surface can be listed. More than two kinds can be used in combination. Among them, metal-coated resin particles are preferred because they rebound after connection and easily maintain contact with the terminal, which is beneficial for stabilizing the conductive performance. In addition, the surface of the conductive particles can be subjected to an insulating treatment that does not hinder the conductive properties by known techniques.

[0049] (Average particle size of filler 4) In the present invention, the average particle size P of the filler 4 is d It can be determined according to the purpose of the filler-containing film. For example, when the filler-containing film is used as a conductive film or an anisotropic conductive film, in order to improve the accuracy of the filler press-in when manufacturing 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. In addition, there is no particular restriction on the upper limit, but in order to suppress the influence of the positional offset of the filler during the manufacture 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 size of the filler can be obtained from a plane image or a cross-sectional image. In addition, the average particle size of the filler as a raw material particle before being included in the filler-containing film can be obtained using a wet flow particle size / shape analyzer FPIA-3000 (manufactured by Malvern Panalytical Ltd.). It should be noted that when particles such as insulating particles are attached to the filler, the diameter without the particles is used as the particle size.

[0050] The average particle size P of fillers in filler-containing films dThe deviation of the CV value (standard deviation / average) is preferably 20% or less. Thus, when the filler-containing film is crimped to the article, the filler-containing film becomes easy to be pressed evenly, which can prevent the pressing force from being locally concentrated. Therefore, when the filler-containing film is constituted as a conductive film or an anisotropic conductive film, the connection stability is improved, and after the connection, the connection state can be accurately evaluated by observing the indentation or the clamping state of the filler. Specifically, in the inspection after the conductive connection or anisotropic conductive connection of electronic components to each other using a conductive film or anisotropic conductive film, the connection state can be accurately confirmed by observing the clamping state of the indentation or the conductive particles, whether it is a component with a larger terminal size (FOB, etc.) or a smaller component (COG, etc.). Therefore, the inspection after the conductive connection or anisotropic connection becomes easy, and it can be expected to improve the productivity of the connection process.

[0051] On the other hand, in the cross-sectional view of the filler-containing film cut along the film thickness direction ( Figure 1A ), preferably, the apex of each filler in the film thickness direction is flush with the 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 the article.

[0052] <"Relationship between Core Film Thickness and Filler Diameter," "Relationship between Filler Diameter and Through-Hole Opening Diameter," and "Relationship between the Compressive Elastic Modulus of the Core Film and the Compressive Elastic Modulus of the Filler"> As described above, the filler-containing film 10 of the present invention has the "relationship between core film thickness and filler diameter," "relationship between filler diameter and through-hole opening diameter," and "relationship between the core film's compressive elastic modulus and the filler's compressive elastic modulus" each limited to specific ranges. Specifically, the present invention satisfies the following equations (1) to (3), and preferably equations (1') to (3').

[0053] C t ≤0.8P d (1) 1.2P d ≤O d (2) E p <E f (3) 0.5P d ≤C t ≤0.8P d (1') 1.2P d ≤O d <1.5P d (2') E p <E f <1.2E p (3').

[0054] (Meaning of formulas (1) and (1')) In the present invention, the reason for focusing on the relationship between the core film thickness and the filler diameter is that this relationship is believed to be closely related to the filler retention of the core film. Specifically, the thickness C of the core film 3 is t The average particle size P of the filler 4 is set to d 0.8 times or less, preferably set to 0.5 times or more and 0.8 times or less. t Exceeding the average particle size P of filler 4 d 0.8 times of the core film 3, the tendency of the filler being difficult to be clamped (the clamping state becomes insufficient) becomes significant. It should be noted that if the thickness C of the core film 3 is t Smaller than the average particle size P of filler 4 d If the diameter of the through hole is 0.5 times that of the through hole, it may not be able to serve as a support for clamping the filler (the effect of the through hole opening diameter on retaining the filler is weakened when press-fitting).

[0055] (Meaning of formulas (2) and (2')) The reason why the present invention focuses on the relationship between the filler diameter and the through-hole opening diameter is that it is believed that by sandwiching the filler with the through-holes of the core film, the sandwiched state can be made uniform and the filler can be fixed in the sandwiched state. Specifically, the opening diameter of the through-hole of the core film 3 is set to d The average particle size P of the filler 4 is set to d 1.2 times or more, preferably less than 1.5 times. This is because if the through hole opening diameter of the core film is d Smaller than the average particle size P of filler 4 d 1.2 times, the opening diameter of the through hole becomes an obstacle when the filler is clamped, making it difficult to flatten. It should be noted that this is because if the opening diameter of the through hole of the core film is O d Let the average particle size P of filler 4 be d If the filler is more than 1.5 times the original diameter, it is easy to cause the filler to be unable to be fixed when clamping.

[0056] (Meaning of formulas (3) and (3')) The reason for focusing on the relationship between the compressive elastic modulus of the core film and the compressive elastic modulus of the filler in the present invention is that it is believed that by allowing the compression of the core film to replace part of the compression of the filler, the combination of filler and core film can be enriched or the degree of freedom can be increased, which can reduce costs and research man-hours. This is also the main purpose of the present invention. Specifically, the compressive elastic modulus E of the core film 3 at room temperature (23°C ± 15°C) is calculated. f Set to be greater than 30% of the compressive elastic modulus E of filler 4 p , preferably less than 1.2 E pThis is because if the compressive elastic modulus E of the core film 3 f Assume that the 30% compression modulus E of filler 4 p Below this value, the tendency of the adhesive layer to flow first becomes significant. If the value is set to 1.2E p Above this value, the core film tends to melt and become unable to fix the filler. f 、E p When the temperature is set to 0°C, the temperature (T0[°C]) showing the lowest melt viscosity of the adhesive layer 2 can be used as a reference. This is because the lowest melt viscosity of the lowest adhesive layer dominates when the laminated state is formed.

[0057] It should be noted that it is preferred that formula (3), preferably formula (3'), is satisfied at a temperature of ± 10°C at the temperature showing the lowest melt viscosity of the adhesive layer 2. This is because if it is outside this range, the possibility of satisfying these formulas is significantly reduced. In addition, the temperature range of T0 [°C] ± 10°C has the meaning of a range in which the compressive elastic modulus of the core film remains approximately constant. If the compressive elastic modulus of the core film remains approximately constant, there is an advantage in that the configuration of the filler can be precisely controlled.

[0058] In the present invention, the 30% compressive modulus of the filler 4 at room temperature (23°C ± 15°C) can be calculated using the following formula: K, which is obtained by measuring the compression displacement of the filler when a compressive load is applied to the filler using a micro-compression tester (e.g., Fischerscope H-100 manufactured by FISCHER). In the formula, "F" is the load value (N) at 30% compressive deformation of the filler, "S" is the compressive displacement (mm) of the filler at 30% compressive deformation, and "R" is the radius (mm) of the filler.

[0059] K[MPa] (N / mm 2 ) = (3 / 2 1 / 2 )·F·S -3 / 2 ·R -1 / 2 In addition, the compressive elastic modulus of the core film 3 at room temperature (23° C.±15° C.) can also be measured using the above-mentioned micro-compression tester.

[0060] <Method for producing filler-containing film> The filler-containing film 10 of the present invention can be manufactured as follows. First, an insulating base layer forming composition 1' ( Figure 2A ), and dried by a conventional method, thereby forming an insulating base layer 1 ( Figure 2B ).

[0061] Then, the core film 3 having the through hole th formed therein by laser processing or photolithography is laminated on the insulating base layer 1 by a known method ( Figure 2C ).

[0062] Next, the filler 4 is spread on the core film 3, and the filler 4 is filled into the through-hole th using a scraper or the like, and the filler 4 not filled into the through-hole th is removed by blowing or the like ( Figure 2D ).

[0063] Finally, the adhesive layer forming composition 2' ( Figure 2E ), and dried by a conventional method, thereby forming an adhesive layer 2 ( Figure 2F ). Thus, a filler-containing film having a release substrate 20 can be obtained. If the release substrate 20 is removed, a filler-containing film can be obtained. Figure 1A The filled film 10 is shown in FIG.

[0064] <How to use the filled film> The filler-containing film of the present invention can be applied to an article and used in the same manner as a conventional filler-containing film, and the article to which it is applied is not particularly limited. Therefore, a joint body in which a first component and a second component are joined via a filler-containing film, and a method for manufacturing a joint body by arranging a filler-containing film between the first component and the second component and joining them are also part of the present invention. For example, when the filler-containing film is configured as a conductive film or an anisotropic conductive film, a crimping tool (such as a hot crimping tool) can be used to apply the conductive film or anisotropic conductive film to a semiconductor element utilizing 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, an FPC, or the like, and a second electronic component such as an FPC, a glass substrate, a plastic substrate, a rigid substrate, or a ceramic substrate, for conductive connection or anisotropic conductive connection. In addition, the filler-containing film can also be used for electronic components for purposes other than conductive connection or anisotropic conductive connection. It should be noted that the surface of the article to which the filler-containing film is to be bonded may be smooth or may have stepped portions or convex portions.

[0065] There are no particular restrictions on the shape, size, and purpose of the first and second electronic components connected by the conductive film or anisotropic conductive film. These electronic components can be small and the terminal size can be narrowed, or the mounting of the electronic components can require high-precision alignment. For example, the bump area is tens of μm. 2 ~Thousands of μm 2Minimized electronic components (such as sub-millimeter LEDs or micro LEDs, etc.) can also be used as connection objects. On the other hand, a conductive film or anisotropic conductive film can be used to install electronic components with large external dimensions. In addition, the installed electronic components can be divided into small pieces for use. In addition, when used for large TVs, etc., sometimes a filler-containing film of more than 1 m, for example, more than 4.5 m, is attached to one side. In this case, in addition to using the filler-containing film as a conductive film or anisotropic conductive film, it can also be used as a spacer film using fillers as spacers, etc.

[0066] The filler-containing film of the present invention, such as a conductive film or an anisotropic conductive film, can be used to stack IC chips or wafers to form a multilayer structure. It should be noted that the electronic components connected via the conductive film or anisotropic conductive film of the present invention are not limited to the examples of electronic components mentioned above. In recent years, it can be used for a variety of diverse electronic components. The present invention includes a film attached body having the filler-containing film of the present invention attached to various articles, and particularly includes a connection structure formed by connecting a first electronic component and a second electronic component via a conductive film or an anisotropic conductive film.

[0067] The method for attaching the filler-containing film to an article can be press-bonding, preferably thermocompression bonding, depending on the intended use of the filler-containing film. Alternatively, light irradiation can be used during the bonding process. An example of light irradiation is the laser lift-off method described in JP-A-2022-151816, where the filler-containing film is separated into individual pieces and then transferred. Resin materials or adhesives suitable for forming filler-containing films suitable for the laser lift-off method can be selected from the materials described in JP-A-2022-151816.

[0068] As a more specific method of using the filler-containing film as a conductive film or an anisotropic conductive film, for example, when the first electronic component is an IC chip and the second electronic component is a substrate, the first electronic component is generally placed on one side of a press tool, the second electronic component is placed on a table opposite the first electronic component, the anisotropic conductive film is pre-attached to the second electronic component, and the first and second electronic components are then pressure-bonded, for example, by thermocompression, using the press tool. In this case, the conductive film or anisotropic conductive film may also be pre-attached to the first electronic component, and the first electronic component is not limited to an IC chip.

[0069] When the first electronic component and the second electronic component are connected by crimping (for example, hot crimping), the resin around the conductive particles can be removed in advance before crimping (for example, hot crimping) as needed, and temporary crimping can be performed. In this way, the influence of the resin flow generated when the conductive film or the anisotropic conductive film is crimped (for example, hot crimping) to the electronic component can be reduced, and unnecessary movement of the conductive particles can be suppressed. Specifically, when one electronic component to be connected is attached to one surface of the conductive film or the anisotropic conductive film, and another electronic component is attached to the other surface of the conductive film or the anisotropic conductive film for temporary crimping, the electronic components are pressed with a press tool to partially remove the resin between the electronic components, and then the electronic components are connected to each other by pressing (for example, hot pressing) as formal crimping (hereinafter, the connection method in which pressing is performed not only during formal crimping but also during temporary crimping is referred to as connection by two-stage press-in). WO2016 / 143789 describes a connection by two-stage press-in using a conductive film or an anisotropic conductive film in which conductive particles are randomly dispersed. However, if such a connection by two-stage press-in is performed when electronic components are connected to each other using a conductive film or an anisotropic conductive film in which conductive particles are regularly arranged as in the present invention, it becomes possible to significantly reduce unnecessary movement of the conductive particles during compression bonding (e.g., hot compression bonding).

[0070] Industrial applicability The filler-containing film of the present invention limits the relationship between the core film thickness and filler diameter, the relationship between the filler diameter and the through-hole opening diameter, and the relationship between the compressive modulus of the core film and the filler to specific ranges. Therefore, when two components are joined via the filler-containing film by compression (e.g., thermocompression), the flow of resin in the core film is suppressed, limiting unintended movement of the filler. Furthermore, uneven compression is suppressed, and the filler is evenly flattened across the entire surface of the film's compression-bonded portion. Therefore, the filler-containing film of the present invention is useful for connecting various electronic components to substrates.

[0071] Explanation of symbols 1 insulating base layer 2 Adhesive layer 3-core membrane 4 Filling 10Filled film 20 Peel off the substrate th through hole P d Average particle size of filler O d Through hole opening diameter C t Core film thickness E f Compressive elastic modulus of core film Ep 30% compression modulus of filler.

Claims

1. A filler-containing film comprising a core film having through-holes sandwiched between an insulating base layer and an adhesive layer, wherein a filler is retained in the through-holes. Satisfy the following equations (1) to (3): C t ≤0.8P d (1) 1.2P d ≤O d (2) AND p <E f (3) Where C t is the thickness of the core film, P d is the average particle size of the filler, O d is the opening diameter of the through hole of the core membrane, E f is the compressive elastic modulus of the core membrane, E p It is the 30% compression modulus of the filler.

2. The filler-containing film according to claim 1, which satisfies the following formulas (1') to (3'): 0.5P d ≤C t ≤0.8P d (1') 1.2P d ≤O d <1.5P d (2') E p <E f <1.2E p (3')。 3 . The filler-containing film according to claim 1 , which satisfies the formula (3) within the range of a temperature T 0 [° C.] ±10° C. showing the lowest melt viscosity of the adhesive layer. The filler-containing film according to claim 2 , which satisfies the formula (3′) within the range of a temperature T 0 [° C.] ±10° C. at which the adhesive layer exhibits the lowest melt viscosity.

5. The filler-containing film according to claim 1 or 2, wherein The lowest melt viscosity of the adhesive layer is lower than the lowest melt viscosity of the insulating base layer.

6. The filler-containing film according to claim 1, wherein The through holes are arranged regularly.

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

8. A conjugate, wherein The first member and the second member are bonded together via the filler-containing film according to claim 1 .

9. A connection structure in which a first electronic component is conductively connected or anisotropically conductively connected to a second electronic component via the filler-containing film according to claim 7 used as a conductive film or an anisotropic conductive film.

10. A method for producing a joined body, wherein: The filler-containing film according to claim 1 is disposed between a first member and a second member and then bonded to each other.

11. A method for manufacturing a connection structure, wherein: A first electronic component is conductively connected or anisotropically conductively connected to a second electronic component via the filler-containing film according to claim 7 used as a conductive film or an anisotropic conductive film.

12. The method for manufacturing a connection structure according to claim 11, wherein: The terminals of the first electronic component and the terminals of the second electronic component are electrically connected via the conductive particles.

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