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

Abstract

Provided is 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 achieving good particle trapping properties when two members are bonded by pressure bonding via the filler-containing film, and also being capable of suppressing the resin flow in the core film and suppressing unnecessary movement of the filler. When a filler-containing film is applied to a conductive film or an anisotropic conductive film, good indentations can be obtained, good conductivity can be achieved between connected electrodes, and the filler-containing film satisfies formula (1) Od > = 2 * Pd-Ct and formula (2) 0.9 * Pd > = Ct. In the formula, Ct is the thickness of the core film, Pd is the average particle diameter of the filler, and Od is the opening diameter of the through hole of the core film.

Description

TECHNICAL FIELD

[0001] The present application relates to a filler-containing film. BACKGROUND

[0002] A filler-containing film in which a filler is dispersed in a resin layer is being used for various purposes such as an antiglare film, a film for capacitors, an optical film, a film for labels, an antistatic film, a conductive film, an anisotropic conductive film, and the like (Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4). In the case where the filler-containing film is heat-pressed to an article to be used, it is desirable to suppress unnecessary flow of the resin forming the filler-containing film and segregation of the filler at the time of heat-pressing from the viewpoint of optical, mechanical, or electrical properties. In particular, in the case where electrically conductive particles are contained as the filler and the filler-containing film is used as a conductive film or an anisotropic conductive film for mounting of electronic parts, if the electrically conductive particles are dispersed at a high density in the insulating resin layer to be able to cope with high-density mounting of electronic parts, the electrically conductive particles are segregated between terminals due to unnecessary movement thereof caused by excessive flow of the resin at the time of mounting of the electronic parts, which becomes a cause of occurrence of short-circuit, and thus it is required to suppress such excessive resin flow.

[0003] In response to such a requirement, an anisotropic conductive film obtained in such a manner that an insulating film provided with through-holes is laminated, electrically conductive particles are filled in the through-holes, and then another adhesive layer is laminated (Patent Document 5) has been proposed. In this anisotropic conductive film, in order to suppress excessive flow of the resin of the insulating film at the time of 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 particle diameter of the electrically conductive particles, and further, the number of the electrically conductive particles per 1 mm 2 The number of the electrically conductive particles in the insulating film is set to be 0.9 times or more and 1.0 times or less of the number of the through-holes.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2006-15680

[0007] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2015-138904

[0008] Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2013-103368

[0009] Patent Document 4: Japanese Patent Application Laid-Open (JP-A) No. 2014-183266

[0010] Patent Document 5: Japanese Patent Application Laid-Open (JP-A) No. 2018-174069 SUMMARY

[0011] Problem to be solved by the invention

[0012] However, in the anisotropic conductive film of Patent Literature 5, factors other than the "relationship between the insulating film thickness and the conductive particle particle diameter" and the "relationship between the conductive particle density and the through-hole density" are not sufficiently focused on as factors for suppressing excessive flow of the resin of the insulating film, and thus, in the anisotropic conductive connection, excessive flow of the resin of the insulating film cannot be sufficiently suppressed, resulting in unnecessary movement of the conductive particles, which can cause a decrease in particle capturing property between the counter electrodes and can make it difficult to achieve good conductivity. In addition, the so-called "indentation", which is an index of the degree of the anisotropic conductive connection state, can also become unclear. In the case of a filler-containing film that sandwiches a core film having a through-hole between an insulating base layer and an adhesive layer and retains a filler in the through-hole, when two members are joined by pressure bonding, such as heat pressure bonding, or the like, with the above-described filler-containing film interposed therebetween, the same problems can occur.

[0013] The present application aims to solve the above problems of the prior art, and in the case of a filler-containing film that sandwiches a core film having a through-hole between an insulating base layer and an adhesive layer and retains a filler in the through-hole, when two members are joined by pressure bonding, such as heat pressure bonding, or the like, with the above-described filler-containing film interposed therebetween, the resin flow of the core film can be suppressed, unnecessary movement of the filler can be limited, good particle capturing property can be achieved, and in the case of applying the filler-containing film to a conductive film or an anisotropic conductive film, good indentation can be obtained, and good conductivity between the connected electrodes can be achieved.

[0014] Solution to the problem

[0015] The present inventors focused on the relationship between the "core film thickness", the "filler particle diameter", and the "through-hole opening diameter", and found that the above-mentioned object can be achieved by defining these in a specific mutual relationship, thereby completing the present application.

[0016] That is, the present application provides a filler-containing film that sandwiches a core film having a through-hole between an insulating base layer and an adhesive layer and retains a filler in the through-hole, and that satisfies the following formulas (1) and (2).

[0017] O d ≥ 2 x P d - C t (1) 0.9 x P d ≥ C t (2)

[0018] In the above formulas (1) and (2), C t is the thickness of the core film, P d is the average particle diameter of the filler, and O dAn opening diameter of a through-hole of the core film. In the case where the conductive particles are used as the filler, the filler-containing film can be used as a conductive film or an anisotropic conductive film.

[0019] Further, the present application provides a joint body obtained by joining a first member and a second member with the above-described filler-containing film of the present application, and preferably provides a connection structure body obtained by electrically or anisotropically connecting a first electronic component to a second electronic component using the filler-containing film used as a conductive film or an anisotropic conductive film. Further, the present application provides a method for manufacturing a joint body, in which the filler-containing film described above is disposed between a first member and a second member, and then the first member and the second member are joined, and preferably provides a method for manufacturing a connection structure body, in which the filler-containing film used as a conductive film or an anisotropic conductive film is used to electrically or anisotropically connect a first electronic component to a second electronic component. In the manufacturing method, it is preferable to electrically connect a terminal of the first electronic component to a terminal of the second electronic component using the conductive particles.

[0020] Effects of the Invention

[0021] In the filler-containing film of the present application, the relationships among the "core film thickness", the "filler particle diameter", and the "through-hole opening diameter" are defined as specific mutual relationships. Therefore, when two members are joined through press bonding, such as heat press bonding, or the like, with the filler-containing film interposed therebetween, the resin flow of the core film can be suppressed, the unintended movement of the filler can be limited, good particle capturing properties can be achieved, and in the case where the filler-containing film is applied to a conductive film or an anisotropic conductive film, good impressions can be obtained, and good conduction properties between the connection electrodes can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1A is a cross-sectional view of the filler-containing film of the present application.

[0023] Figure 1B is a cross-sectional view of the filler-containing film of the present application. Figure 1A is a partially enlarged cross-sectional view of the filler-containing film of the present application.

[0024] Figure 2A is an explanatory diagram of the manufacturing method of the filler-containing film of the present application.

[0025] Figure 2B is an explanatory diagram of the manufacturing method of the filler-containing film of the present application.

[0026] Figure 2C is an explanatory diagram of the manufacturing method of the filler-containing film of the present application.

[0027] Figure 2D is an explanatory diagram of the manufacturing method of the filler-containing film of the present application.

[0028] Figure 2Eis a diagram of the manufacturing method of the filler-containing film of the present application.

[0029] Figure 2F is a diagram of the manufacturing method of the filler-containing film of the present application. DETAILED DESCRIPTION

[0030] Hereinafter, one example of the filler-containing film of the present application will be described in detail with reference to the drawings. Note that the same reference numerals are used throughout the drawings to refer to the same or like components.

[0031] <Overall configuration of the filler-containing film 10>

[0032] Figure 1A is a cross-sectional view of the filler-containing film 10 of the present application. The filler-containing film 10 is characterized by having a structure in which a core film 3 having a through-hole th is interposed between an insulating base layer 1 and an adhesive layer 2 and a filler 4 is held in the through-hole th, and the filler-containing film 10 satisfies the following formulas (1) to (2), preferably formulas (1') and (2').

[0033] O d ≥ 2 x P d - C t (1) 0.9 x P d ≥ C t (2)

[0034] 2 x P d ≥ O d ≥ 2 x P d - C t (1')

[0035] 0.9 x P d ≥ C t ≥ 0.3 x P d (2')

[0036] In these formulas, according to a partial enlarged cross-sectional view of the periphery of the filler 4 of the filler-containing film 10 of the present application Figure 1B C t is the layer thickness [μm] of the core film, P d represents the average particle diameter [μm] of the filler, and O d represents the opening diameter [μm] of the through-hole of the core film.

[0037] <Insulating base layer 1>

[0038] When the filler-containing film 10 is manufactured, the insulating base layer 1 constituting the filler-containing film 10 of the present application is a layer that becomes a base on which the core film is formed. Such an insulating base layer 1 can be constituted by a single insulating resin layer or by a laminate of a plurality of insulating resin layers. Furthermore, the insulating base layer 1 is preferably adhesive.

[0039] (Resin composition constituting the insulating base layer 1)

[0040] The resin composition constituting the insulating base layer 1 can be appropriately selected depending on the use of the filler-containing film, and for example, a thermoplastic resin composition, a high-viscosity adhesive resin composition, or a curable resin composition can be listed. For example, in the case where the filler-containing film is used as an electrically conductive film or an anisotropic conductive film, a curable resin composition formed of a polymerizable compound and a polymerization initiator can be used as in the case of the existing resin composition forming an insulating resin layer of an electrically 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 they can be used in combination. For example, as the thermal polymerization initiator, a thermal cationic polymerization initiator can be used; as the thermally polymerizable compound, an epoxy resin can be used; as the photopolymerization initiator, a photoradical polymerization initiator can be used; and as the photopolymerizable compound, an acrylate compound can be used. As the thermal polymerization initiator, a thermal anionic polymerization initiator can also be used. As the thermal anionic polymerization initiator, a microcapsule-type latent curing agent in which an imidazole modifier is used as a core and the surface thereof is coated with a polyurethane is preferably used.

[0041] (Lowest melt viscosity of the insulating base layer 1)

[0042] When the filler-containing film 10 is pressure-bonded, for example, thermocompression-bonded to an article, in order to suppress unnecessary movement of the filler 4 due to resin flow and to induce moderate flow of the resin, the lowest melt viscosity of the insulating base layer 1 can be 200 Pa s or more, preferably 1500 Pa s or more, more preferably 2000 Pa s or more, further preferably 3000 Pa s or more, and preferably 15000 Pa s or less, more preferably 10000 Pa s or less, further preferably 8000 Pa s or less. One example of the lowest melt viscosity can be obtained in such a manner that, using a rotational rheometer (manufactured by TA Instruments, Inc.), the lowest melt viscosity is obtained using a measuring plate having a diameter of 8 mm after the measurement pressure of 5 g is kept constant, and more specifically, the lowest melt viscosity can be obtained under conditions in which the temperature range is 30 to 200°C, the temperature increase rate is 10°C / minute, the measurement frequency is 10 Hz, and the load variation to the above measuring plate is 5 g. Note that the lowest melt viscosity can be adjusted depending on the kind, the blending amount of the fine solid component as a melt viscosity adjusting agent, the change in the preparation conditions of the resin composition, and the like.

[0043] (Thickness of the insulating base layer 1)

[0044] In order to stably hold the core film 3 and the filler 4, and the like, the thickness of the insulating base layer 1 with respect to the average particle diameter P of the filler 4 d, preferably 0.6 times or more, more preferably 1.2 times or more, and further preferably 1.5 times or more. In addition, as for the upper limit of the layer thickness of the insulating base layer 1, in order to avoid unnecessary movement of the filler 4 due to resin flow, the layer thickness is preferably 10 times or less, more preferably 5 times or less, relative to the average particle diameter P of the filler 4 d , preferably 10 times or less, and more preferably 5 times or less. The layer thickness can be measured using a well-known thickness gauge or film thickness meter.

[0045] (Adhesion of the insulating base layer 1)

[0046] In the case of the insulating base layer 1, it is preferable that, for the purpose of pressure bonding, such as heat pressure bonding, of the filler-containing film, it has an adhesion that enables temporary pressure bonding before pressure bonding. The adhesion can be measured in accordance with JIS Z 0237, and in addition, it can also be measured in the form of tack force using a probe method in accordance with JIS Z 3284-3 or ASTM D 2979-01. As for the tack force of the adhesive layer 2 constituting the filler-containing film 10 obtained using the probe method, for example, when measurement is performed under conditions of a pressure application speed of a probe of 30 mm / minute, a pressure application pressure of 196.25 gf, a pressure application time of 1.0 sec, a peeling speed of 120 mm / minute, and a measurement temperature of 23°C ± 5°C, it is preferably 1.0 kPa (0.1 N / cm 2 ) or more, more preferably 1.5 kPa (0.15 N / cm 2 ) or more, and further preferably 3.0 kPa (0.3 N / cm 2 ) or more.

[0047] In addition, the adhesion of the filler-containing film can also be found by the adhesion strength test described in Japanese Patent Application Publication No. 2017-48358. In this adhesion strength test, for example, the filler-containing film 10 is sandwiched using two glass plates, one of the glass plates is fixed, and the other glass plate is peeled at a peeling speed of 10 mm / minute at a test temperature of 50°C, at which time, since the adhesion state of the fixed glass plate and the filler-containing film is previously strengthened, the adhesion of the peeled glass plate and one surface of the filler-containing film adhered to the glass plate can be measured. The adhesion strength (adhesion) thus measured is preferably set to 1 N / cm 2 (10 kPa) or more, and more preferably 10 N / cm 2 (100 kPa) or more. The adhesion strength is the adhesion between one surface of the filler-containing film in the peeling direction and the peeled article.

[0048] In addition, the adhesion of the filler-containing film can also be found by the following test, in which one end of a test piece is opposed and adhered (bonded), and the other end is pulled to peel the test piece. The adhesion measured using this test method can be the same as the above-described adhesion strength test (1 N / cm2 (10 kPa) or more). If the adhesion force is large enough (e.g., 10 N / cm or more) by the adhesion strength test, the adhesion force in the test method can be 10% or more of the adhesion force by the adhesion strength test. 2 (100 kPa) or more), the adhesion force in the test method can be 10% or more of the adhesion force by the adhesion strength test.

[0049] Such adhesion can be adjusted in such a manner that the resin composition constituting the insulating base layer is appropriately adjusted, and in addition, the smoothness of the insulating base layer forming the outer surface of the filler-containing film is improved by the following production method of the filler-containing film.

[0050] <Adhesion Layer 2>

[0051] The adhesion layer 2 constituting the filler-containing film 10 of the present application is a layer for temporarily pressure-bonding the filler-containing film 10 to an article using the filler-containing film 10. Such an adhesion layer 2 can be constituted by a single insulating resin layer, or can be constituted by a laminate of a plurality of insulating resin layers.

[0052] (Resin Composition Constituting Adhesion Layer 2)

[0053] The resin composition constituting the adhesion layer 2 is appropriately selected in accordance with the use of the filler-containing film, and for example, a thermoplastic resin composition, a high-viscosity adhesive resin composition, or a curable resin composition can be cited. For example, in the case where the filler-containing film is used as an electrically conductive film or an anisotropically conductive film, a curable resin composition formed of a polymerizable compound and a polymerization initiator can be used, similarly to the existing resin composition forming the adhesion layer of the electrically conductive film or the anisotropically conductive film. In this case, as the polymerization initiator, a thermal polymerization initiator can be used, or a photopolymerization initiator can be used, or they can be used in combination. For example, as the thermal polymerization initiator, a thermal cationic polymerization initiator can be used; as the thermopolymerizable compound, an epoxy resin can be used; as the photopolymerization initiator, a photoradical polymerization initiator can be used; and as the photopolymerizable compound, an acrylate compound can be used. As the thermal polymerization initiator, a thermal anionic polymerization initiator can also be used. As the thermal anionic polymerization initiator, a microcapsule-type latent curing agent having an imidazole modifier as a core and a polyurethane coating on the surface thereof is preferably used.

[0054] (Lowest Melt Viscosity of Adhesion Layer 2)

[0055] The minimum melt viscosity of the adhesive layer 2 can be the same as that of the above-mentioned insulating base layer 1. It can be intentionally set to be lower than that of the insulating base layer 1, or it can be intentionally set to be higher than that of the insulating base layer 1. By adjusting the minimum melt viscosities (and thicknesses) of the insulating base layer 1 and the adhesive layer 2, the resin flow can be finely controlled when the filler-containing film 10 is press-bonded, for example, heat-press-bonded to an article, and application to various uses can be expected. In the case where the filler-containing film is used as a conductive film or an anisotropic conductive film, the unnecessary movement of the filler (i.e., the conductive particles) can be more finely suppressed.

[0056] (Thickness of the adhesive layer 2)

[0057] The thickness of the adhesive layer 2 can be the same as that of the above-mentioned insulating base layer 1. It can be intentionally set to be lower than that of the insulating base layer 1, or it can be intentionally set to be higher than that of the insulating base layer 1. Specifically, it is preferably 0.1 μm or more, and more preferably 0.5 μm or more. In the case where the filler-containing film is used for attachment, it is preferable to make the adhesive layer 2 thin. In order to fill between the members to be joined, the thickness of the adhesive layer 2 can also be 20 μm or more. If the thickness is too thick, in the case where a roll is produced, the resin can exude, and thus it is preferably 50 μm or less. Thus, the upper limit can be appropriately set according to the purpose.

[0058] (Adhesive force of the adhesive layer 2)

[0059] With respect to the adhesive layer 2, it is preferable that, with respect to the article to which the filler-containing film is press-bonded, for example, heat-press-bonded, it has an adhesive force that can temporarily press-bond before press-bonding. The adhesive force of such an adhesive layer 2 can be the same as that of the insulating base layer 1, or it can be stronger than that of the insulating base layer 1, or it can be weaker than that of the insulating base layer 1. With respect to the adhesive force of the adhesive layer 2 and the adhesive force of the insulating base layer 1, it is possible to optimize them respectively from the viewpoint of whether the surface of the article to which the filler-containing film is attached is the insulating base layer 1 or the adhesive layer 2, and the degree of adhesive force required for the article to be placed.

[0060] <Core film 3>

[0061] The core film 3 constituting the filler-containing film 10 of the present application is a layer for suppressing the unintended movement of the conductive particles due to the resin flow of the insulating base layer 1 and the adhesive layer 2, and has a function as a spacer sheet, and the core film 3 has a through hole th for filling the filler 4. Such a core film 3 can be composed of a single insulating resin layer, or it can be composed of a laminate of a plurality of insulating resin layers.

[0062] (Resin composition constituting the core film 3)

[0063] As the resin composition constituting the core film 3, a thermoplastic resin composition such as a phenoxy resin, a polyimide resin, a polyamide resin, a polyacetal resin, a polycarbonate resin, a polyethylene resin, a polypropylene resin, a polystyrene resin, a polyvinyl chloride resin, a polyvinyl acetate resin, or the like; a high viscosity adhesive resin composition; or a curable resin composition such as an epoxy resin, an acrylic resin, or the like, or a mixture thereof, is appropriately selected according to the purpose of the filler-containing film 10.

[0064] (Melt viscosity of core film 3)

[0065] When the filler-containing film 10 is pressure-bonded, for example, heat-bonded to an article, in order to suppress unnecessary movement of the filler 4 due to resin flow, the melt viscosity of the core film 3 at the temperature range at which pressure-bonding is performed is preferably 1.1 times or more, more preferably 1.2 times or more, relative to the lowest melt viscosity of the insulating base layer 1. One example of the melt viscosity can be obtained in such a manner that, using a rotational rheometer (manufactured by TA Instruments, Inc.), after the measurement pressure 5 g is kept fixed, the melt viscosity is obtained using a measuring plate having a diameter of 8 mm, and more specifically, the melt viscosity can be obtained at a temperature range of 30 to 250°C, at a temperature increase rate of 10°C / minute, a measurement frequency of 10 Hz, and a load variation of 5 g to the above measuring plate. Note that the melt viscosity can be adjusted according to the type, the blending amount of the fine solid component as a melt viscosity adjustor, the change of the preparation conditions of the resin composition, and the like.

[0066] (Thickness of core film 3)

[0067] The thickness of the core film 3 is determined in relation to the average particle diameter P d of the filler 4. This will be described later.

[0068] (Through hole th of core film 3)

[0069] The core film 3 is formed with a through hole th for filling and holding the filler 4. The through hole th is respectively open at the adhesive layer 2 side and the insulating base layer 1 side. Generally, the opening diameter at the adhesive layer 2 side and the opening diameter at the insulating base layer 1 side are the same size.

[0070] The opening diameter O d of the through hole th is dependent on the thickness C t of the core film 3 determined in consideration of the purpose of the filler-containing film, the average particle diameter P d of the filler 4, and the like, and if the opening diameter O d is too small, the filler cannot be accommodated, and therefore the opening diameter O dThe average particle size of the filler is 1.1 times or more, preferably 1.2 times or more, and more preferably 1.3 times or more. d If the average particle size of the filler is too large, the filler cannot be retained. Therefore, the opening diameter O d The opening diameter O can be selected from this range according to the thickness of the core film. d .

[0071] Such through holes th can be arranged in an irregular pattern on the core film 3, or they can be arranged in a regular pattern. Such a through hole pattern is substantially the same as the presence pattern of the filler in the filler-containing film 10. Examples of regular patterns include: lattice arrangements such as square lattices, rectangular lattices, and rhombus lattices. It can also be a pattern composed of a combination of lattices of various shapes. By being a regular pattern, the advantage of easy quality management can be listed. It is also possible to arrange through hole rows in which through holes th are arranged linearly at prescribed intervals side by side at prescribed intervals. It is also possible to arrange areas where through holes th are densely arranged and areas where through holes th are sparsely arranged in a regular repeating pattern. In the case of using the filler-containing film as a conductive film or an anisotropic conductive film, in order to simultaneously achieve terminal capture stability and suppress short circuits, it is more preferred that the through holes th are separated from each other and arranged regularly. Whether the through holes th are regularly arranged can be determined by observing whether the through holes th or the predetermined arrangement of the fillers are repeated in the longitudinal direction of the film (the winding direction when the filler-containing film is made into a package).

[0072] In addition, the filling rate of the filler in the through hole th can be calculated according to {(the number of fillers / the number of through holes) × 100 (%)}. This filling rate can be calculated by observing the visual field of the membrane surface in the same way as the number density described below. The filler filling rate only needs to be 95% or more, preferably 98% or more, and more preferably 99.5% or more. Ideally, the residual filler (residual rate) that is not filled into the through hole th is small (close to zero), but in practical terms, the residual rate can be less than 2% relative to the number of through holes th, preferably less than 1%, and more preferably less than 0.5%. The reason is that if an exclusion operation is performed to make the residual rate close to zero, it may cause defects on the membrane surface.

[0073] The distance between through holes th can be determined according to the connected objects and the purpose. In addition, the number density of through holes th is usually as long as 10 / mm 2 More than 30 pieces / mm is preferred 2 Above, the upper limit is 500,000 pieces / mm 2The following is preferable, and 250,000 pieces / mm is more preferable 2 The following is more preferable, and 100,000 pieces / mm is even more preferable 2 The following is preferable. The number density can be determined by observing the field of view of the film surface using a microscope. The observation area when using a microscope is preferably 2 mm 2 The above, and 10 mm 2 The above is preferable.

[0074] The number density of the through holes th and the filler can be determined by observation using a metal microscope, or can be determined by measuring the observed image using image analysis software (for example, WinROOF (manufactured by San-Ei Gen F.F.I., Inc.), or Azokun (registered trademark) (manufactured by Asahi Kasei Engineering Corporation), etc.). The observation method and the measurement method are not limited by the above.

[0075] In the present application, by unifying the size of the through holes th, the effects of the present application can be more remarkably exhibited. For this reason, it is desirable that the size and the depth of the opening portion of the through holes th satisfy the following conditions. That is, in the filler-containing film, 95% or more, preferably 98% or more, and more preferably 99.5% or more of the total number of the through holes th contained in the region in which the number of the through holes th is 1,000 or more (preferably 2,000 or more) in the range of 1 mm 2 The above, and 2 mm 2 In the above range, it is desirable that the size and the depth of the opening portion of the through holes th are uniform in 95% or more, preferably 98% or more, and more preferably 99.5% or more of the total number of the through holes th contained in the region in which the number of the through holes th is 1,000 or more (preferably 2,000 or more). Here, "uniform" in the "size and the depth of the opening portion" means that, on the basis of taking into account the measurement error, the size and the depth of the opening portion of a certain through hole th fall within the range of ± 15% or less, preferably ± 10% or less, and more preferably ± 5% or less of the average size and the average depth of the opening portion of the through holes th contained in each of the prescribed regions. Note that, since there are cases in which the shape of the opening portion is different, the size of the opening portion can also be the diameter in the case in which the area of the opening portion is converted to a circle.

[0076] <Filler 4>

[0077] In the present application, as the filler 4, from the viewpoint of the use of the filler-containing film, an inorganic filler (metal particle, metal oxide particle, metal nitride particle, etc.), an organic filler (resin particle, rubber particle, etc.), a filler in which an organic material and an inorganic material are mixed (for example, a particle in which a core is formed of a resin material and the surface is plated with a metal (metal-coated resin particle), a filler in which an insulating fine particle is attached to the surface of a conductive particle, a filler in which the surface of a conductive particle is subjected to an insulating treatment, etc.) are appropriately selected according to the performance required by the use such as hardness, optical performance, etc. For example, in an optical film, a mat film, a silica filler, a titanium oxide filler, a styrene filler, an acrylic filler, a melamine filler, or various titanate fillers, etc. can be used. In a capacitor film, a titanium oxide filler, a magnesium titanate filler, a zinc titanate filler, a bismuth titanate filler, a lanthanum oxide filler, a calcium titanate filler, a strontium titanate filler, a barium titanate filler, a barium zirconium titanate filler, a lead zirconium titanate filler, and a mixed filler thereof, etc. can be used. In an adhesive film, a polymer-based rubber particle, a silicone rubber particle, etc. can be contained. In a conductive film, an anisotropic conductive film, a conductive particle can be contained. As the conductive particle, a metal particle such as nickel, cobalt, silver, copper, gold, palladium, etc., an alloy particle such as solder, etc., a metal-coated resin particle, a metal-coated resin particle in which an insulating fine particle is attached to the surface, etc. can be listed. Two or more kinds can also be used in combination. Among them, from the viewpoint of easily maintaining contact with a terminal after connection and stable conduction performance, a metal-coated resin particle is preferred. Furthermore, an insulating treatment can be performed on the surface of the conductive particle by a known technique without hindering the conduction characteristics.

[0078] (Average particle diameter of the filler 4)

[0079] In the present application, the average particle diameter P d may be determined according to the use of the filler-containing film. For example, in the case where the filler-containing film is used as a conductive film or an anisotropic conductive film, in order to improve the press-in accuracy of the filler at the time of manufacturing the filler-containing film, the average particle diameter P d is preferably 1 μm or more, more preferably 1.4 μm or more, and further preferably 2.5 μm or more. Furthermore, the upper limit is not particularly restricted, and in order to suppress the influence of the positional deviation of the filler at the time of manufacturing the filler-containing film, the average particle diameter P d is preferably 200 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less. The average particle diameter P dThe average particle diameter of the filler contained in the filler-containing film can be determined using a wet flow-type particle diameter-shape analyzer FPIA-3000 (manufactured by Malvern Panalytical) from a planar image or a cross-sectional image. Note that, in the case where the filler is attached with fine particles such as insulating fine particles, the particle diameter excluding the fine particles is used as the particle diameter.

[0080] The average particle diameter P of the filler in the filler-containing film d is preferably 20% or less in terms of CV (standard deviation / average). Thus, when the filler-containing film is press-bonded to an article, the filler-containing film is easily uniformly pressed, and it is possible to prevent the local concentration of the pressing force. Therefore, in the case where the filler-containing film is configured as a conductive film or an anisotropic conductive film, the stability of the connection is improved, and after the connection, it is possible to accurately evaluate the connection state by observing the pressing marks and the clamping state of the filler. Specifically, in the inspection after the conductive connection or the anisotropic conductive connection of electronic parts using a conductive film or an anisotropic conductive film, whether the terminal size is relatively large (FOB (Film on Board) or the like) or relatively small (COG (Chip on Glass) or the like), it is possible to accurately confirm the connection state by observing the pressing marks and the clamping state of the conductive particles. Therefore, the inspection after the conductive connection or the anisotropic conductive connection becomes easy, and it is possible to expect an improvement in the productivity of the connection process.

[0081] On the other hand, in a cross-sectional view of the filler-containing film after being cut along the film thickness direction (A-A), Figure 1A , it is preferable that the apexes of the respective fillers in the film thickness direction are aligned on a plane parallel to the interface between the insulating base layer 1 and the core film 3. Thus, it is easy to uniformly press-bond the filler-containing film to an article.

[0082] <Relationship between the thickness of the core film, the average particle diameter of the filler, and the opening diameter of the through-hole of the core film>

[0083] As described above, the relationships between the "thickness of the core film", the "average particle diameter of the filler", and the "opening diameter of the through-hole" of the filler-containing film 10 of the present application described above satisfy the following formulas (1) and (2), and preferably satisfy the formulas (1') and (2').

[0084] O d ≥ 2 x P d - C t (1) 0.9 x P d ≥ C t (2)

[0085] 2 x P d ≥ O d ≥ 2 x P d - Ct (1')

[0086] 0.9×P d ≥C t ≥0.3×P d (2')

[0087] (Meaning of Formulas (1) and (1'))

[0088] The reason why the present invention focuses on the relationship between the thickness of the core film, the average particle size of the filler, and the opening diameter of the through-holes in the core film is that the amount of filler movement in the film surface direction and the amount of filler movement in the film thickness direction are important in order to accurately retain the filler after clamping. d Simply set it as the average particle size P of filler 4 d 2 times the value minus the thickness of the core film C t The reason for setting it this way is that, when clamping, by increasing the amount of movement of the filler in the membrane surface direction, the filler is accommodated within the opening diameter and is easily clamped (crushed). In other words, a certain degree of freedom is given in the membrane surface direction. Then, the opening diameter of the through hole is set to satisfy the formula d The average particle size P of the filler 4 is set to d The reason for this setting is that the amount of movement in the film thickness direction (compressed state, crushed state) is adjusted according to the amount of movement of the filler in the film surface direction. In other words, the surface of the core membrane supporting the filler (the surface inside the through hole) in the state of sandwiching the filler is suppressed to a certain amount relative to the filler.

[0089] (Meaning of formulas (2) and (2'))

[0090] The reason why the present invention focuses on the relationship between the average particle size of the filler and the thickness of the core film is that, as mentioned above, the surface between the filler and the inner side of the through hole (i.e., the thickness of the core film) needs to maintain a minimum required area. Specifically, if the core film is too thick relative to the filler, the force applied to the filler will be reduced, which will have a negative impact on the clamping. Therefore, the thickness C of the core film 3 is set to t The average particle size P of the filler 4 is set to d In addition, if the core film is too thin relative to the filler, it is difficult for the core film to suppress the movement of the filler in the film surface direction, and it is difficult to precisely arrange the filler after the film is pressed. Therefore, the thickness C of the core film 3 is set to t The average particle size P of the filler 4 is set to d It is preferably 0.3 times or more, more preferably 0.4 times or more.

[0091] <Method for producing a filler-containing film>

[0092] The filler-containing film 10 of the present invention can be produced as follows. First, the insulating base layer forming composition 1' is applied to a release substrate 20 having a smooth surface such as a PET film ( Figure 2A ), and dried by conventional methods to form an insulating base layer 1 ( Figure 2B ).

[0093] Then, the core film 3 having the through hole th formed therein by laser processing, photolithography processing, stamping processing, etc. is laminated on the insulating base layer 1 by a known method ( Figure 2C ).

[0094] Next, the filler 4 is spread in the core film 3, and the filler 4 is filled into the through-holes th using a scraper or the like, and the filler 4 not filled into the through-holes th is removed by air blowing or the like ( Figure 2D ).

[0095] Finally, the adhesive layer forming composition 2' is applied on the core film 3 ( Figure 2E ), and dried by conventional methods to form 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 Filled film 10 is shown.

[0096] How to use filled film

[0097] The filler-containing film of the present invention can be applied to an article for use, similarly to existing filler-containing films, and the articles applied are not particularly limited. Therefore, a joint body obtained by joining a first component and a second component 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 utilizing the joining 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 the anisotropic conductive film to a conductive connection or an anisotropic conductive connection between a first electronic component and a second electronic component. The first electronic component includes a semiconductor element utilizing PN bonding (a power generation element such as a solar cell, an imaging element such as a CCD, a light-emitting element, a Peltier element), various other semiconductor elements, an IC chip, an IC module, an FPC, etc.; the second electronic component includes an FPC, a glass substrate, a plastic substrate, a rigid substrate, a ceramic substrate, etc. In addition, the filler-containing film can also be used for electronic components in uses other than conductive connection and anisotropic conductive connection. The surface of the article to which the filler-containing film is bonded may be smooth or may have steps or convex shapes.

[0098] The shape, size, and use of the first electronic component and the second electronic component connected by the conductive film or the anisotropic conductive film are not particularly limited. These electronic components can be small and have fine terminal sizes, or can require high-precision alignment for mounting of the electronic components. For example, electronic components (e.g., mini LEDs, micro LEDs, and the like) that are super-miniaturized to have a bump area of tens of μm 2 to several thousand μm 2 may also be used as connection targets. On the other hand, electronic components having a large outer size can also be mounted using the conductive film or the anisotropic conductive film. In addition, the mounted electronic components can be used by being divided and miniaturized. Furthermore, in the case of use in a large television or the like, the filler-containing film can sometimes be attached to one side to a size of 1 m or more, for example, 4.5 m or more. In this case, in addition to the filler-containing film being used as the conductive film or the anisotropic conductive film, the filler-containing film can also be used as a spacer film or the like in which the filler serves as a spacer.

[0099] The filler-containing film of the present application, for example, the conductive film or the anisotropic conductive film, can also be used to stack IC chips or wafers to be multi-layered. Note that the electronic components connected by the conductive film or the anisotropic conductive film of the present application are not limited by the examples of the electronic components described above. In recent years, the conductive film or the anisotropic conductive film of the present application can be used in a wide variety of electronic components. The present application includes a film-attached body in which the filler-containing film of the present application is attached to various articles, and particularly includes a connection structure in which a first electronic component and a second electronic component are connected via the conductive film or the anisotropic conductive film.

[0100] Regarding the method of attaching the filler-containing film to an article, depending on the use of the filler-containing film, pressure bonding, for example, heat pressure bonding can be performed, or light irradiation can be used at the time of attachment. As one example of the use of light irradiation, a method in which the filler-containing film is singulated using a laser lift-off method and then transferred can be cited from Japanese Patent Application Publication No. 2022-151816. As a resin material or an adhesive material to be used for the filler-containing film to be produced for the laser lift-off method, a material described in Japanese Patent Application Publication No. 2022-151816 can be selected and used.

[0101] In the case where the filler-containing film is configured as the conductive film or the anisotropic conductive film, as a more specific method of use, for example, in the case where the first electronic component is an IC chip and the second electronic component is a substrate, the first electronic component is generally placed on the side of a pressing tool, the second electronic component is placed on a stage opposite the first electronic component, the conductive film or the anisotropic conductive film is attached to the second electronic component in advance, and heat pressure bonding of the first electronic component and the second electronic component is performed using the pressing tool. In this case, the conductive film or the anisotropic conductive film can also be attached to the first electronic component in advance, and the first electronic component is not limited to an IC chip.

[0102] When the first electronic component and the second electronic component are connected by pressure bonding, such as thermal pressure bonding, the resin around the conductive particles can be preliminarily excluded before pressure bonding, as necessary, and temporary pressure bonding can be performed. Thus, the influence of resin flow generated when the conductive film or the anisotropic conductive film is pressure bonded, such as thermally pressure bonded, to an article such as an electronic component is reduced, and unnecessary flow of the conductive particles can be suppressed. Specifically, when one electronic component to be connected is attached to one face of the conductive film or the anisotropic conductive film, and the other electronic component is attached to the other face of the conductive film or the anisotropic conductive film, and temporary pressure bonding is performed, the electronic components are pressed by a pressing tool, a part of the resin between the electronic components is excluded, and then the electronic components are connected to each other by performing pressing (e.g., thermal pressing) as formal pressure bonding (hereinafter, the connection method in which pressing is performed not only at the time of formal pressure bonding but also at the time of temporary pressure bonding will be referred to as connection based on two-stage pressing). The use of the conductive film or the anisotropic conductive film in which the conductive particles are randomly dispersed for connection based on two-stage pressing is described in WO2016 / 143789. In the case where the electronic components are connected to each other using the conductive film or the anisotropic conductive film in which the conductive particles are regularly arranged according to the present application, if such connection based on two-stage pressing is performed, unnecessary flow of the conductive particles can be significantly reduced at the time of pressure bonding, such as thermal pressure bonding.

[0103] [Examples]

[0104] Hereinafter, the present application will be specifically described according to examples. The respective compositions of the resin composition for forming an insulating base layer, the resin composition for forming a core film, and the resin composition for forming an adhesive layer used in the examples are shown below.

[0105] <Composition of the resin composition for forming an insulating base layer>

[0106] Phenoxy resin (YP-50, Nippon Ferrosilicon Co., Ltd.) 40 parts by mass

[0107] Silica filler (Aerosil R805, Nippon Aerosil Co., Ltd.) 25 parts by mass

[0108] Liquid epoxy resin (jER828, Mitsubishi Chemical Corporation) 30 parts by mass

[0109] Silane coupling agent (KBM-403, Shin-Etsu Chemical Co., Ltd.) 2 parts by mass

[0110] Thermocationic polymerization initiator (SI-60L, Sumitomo Chemical Co., Ltd.) 3 parts by mass

[0111] <Composition of the resin composition for forming a core film>

[0112] Phenoxy resin (PKFE, PAR Industrial Co., Ltd.) 70 parts by mass

[0113] Fumed silica (RY200, Nippon Aerosil Co., Ltd.) 30 parts by mass

[0114] <Resin composition for adhesive layer formation>

[0115] Phenoxy resin (YP-50, Nippon Iron Steel Chemical Co., Ltd.) 40 parts by mass

[0116] Silica filler (Aerosil R805, Nippon Aerosil Co., Ltd.) 5 parts by mass

[0117] Liquid epoxy resin (jER828, Mitsubishi Chemical Co., Ltd.) 50 parts by mass

[0118] Silane coupling agent (KBM-403, Shin-Etsu Chemical Co., Ltd.) 2 parts by mass

[0119] Thermal cationic polymerization initiator (SI-60L, Sumitomo Chemical Co., Ltd.) 3 parts by mass

[0120] Examples 1 to 3

[0121] A release film (50 μm thick) made of polyethylene terephthalate on the surface of which a release treatment was performed was prepared, and the above-mentioned resin composition for insulating base layer formation and the resin composition for adhesive layer formation were prepared, respectively, using these resin compositions, the operation was performed in the same manner as in Example 3 of Japanese Patent No. 6187665 to obtain an insulating base layer film 6.00 μm thick and an adhesive layer film 1.0 μm thick. Further, a core film having a through-hole with an opening diameter O d [μm] of Table 1 and having a layer thickness C t [μm] of Table 1 was obtained by the following manner, that is, after a coating liquid was prepared from the above-mentioned mixture of resin composition for core film formation (diluted to 20% of solid content with a general solvent), a mold substantially the same as that described in paragraph 0111 of Japanese Patent No. 6187665 was prepared using transparent polycarbonate-based particles, the above-mentioned coating liquid was coated on the mold, and drying was performed by placing in a drier at 60°C for 5 minutes.

[0122] Conductive particles (Shikoku Chemicals Corp.), Micropearl (metal-coated resin particles), and an average particle diameter P d [3.40 μm] were prepared as fillers. After the core film and the insulating base layer film were laminated, the fillers were filled in the through-holes, and the adhesive layer film was laminated. The lamination of the films and the filling of the fillers were performed in substantially the same manner as in Japanese Patent No. 6187665. Thus, the anisotropic conductive film of Examples 1 to 3 was obtained as a filler-containing film. The number density of the fillers was 28000 pieces / mm2 .

[0123] Evaluation

[0124] For the obtained filler-containing film, "immobility" of the filler (particle catchability when the filler-containing film is used as an anisotropic conductive film), "indentation", and "conductive property (conductive resistance)" were evaluated in the following manner.

[0125] (Immobility)

[0126] In order to evaluate the immobility of the filler, particle catchability was evaluated. Specifically, the filler-containing film of each example and comparative example was sandwiched between a particle catchability evaluation IC and a glass substrate (ITO wiring) having a corresponding terminal (bump) pattern in a manner that the alignment was shifted by 6 μm, and was subjected to heat and pressure (180°C, 60 MPa, 5 seconds), thereby producing an evaluation connection structure. In the evaluation connection structure, the number of captured conductive particles was measured in 100 regions of 6 μm x 66.6 μm in which the bump of the evaluation IC and the terminal of the glass substrate overlapped, the lowest number of captures was found, and evaluation was performed in accordance with the following particle catchability evaluation criteria. The obtained results are shown in Table 1. As for the immobility, it is desirable to be evaluated as A or B in terms of practical use.

[0127] Particle catchability evaluation IC

[0128] Outer dimensions: 1.6 x 29.8 mm.

[0129] Thickness: 0.3 mm.

[0130] Bump specifications: 12 μm wide x 66.6 μm long, bump pitch 22 μm (L / S = 12 μm / 10 μm), bump height 12 μm.

[0131] Immobility (particle catchability) evaluation criteria

[0132] A: The lowest number of captures was 5 or more.

[0133] B: The lowest number of captures was 3 or more and less than 5.

[0134] C: The lowest number of captures was 1 or more and less than 3.

[0135] D: The lowest number of captures was 0.

[0136] (Indentation)

[0137] For 200 conductive particles in the connection structure for immobility evaluation, the average particle diameter of the conductive particles was investigated, the proportion of the number of conductive particles whose average particle diameter after crimping was 80% or less of the average particle diameter of the conductive particles before crimping was calculated, and evaluation was performed in accordance with the following indentation evaluation criteria. In terms of practical use, A or B evaluation is preferable.

[0138] Indentation evaluation criteria

[0139] Rank: Criteria.

[0140] A: 80% or more.

[0141] B: 60% or more and less than 80%.

[0142] C: Less than 60%.

[0143] (Conductivity)

[0144] Each anisotropic conductive film of each example as a filler-containing film was sandwiched between an IC for conductivity evaluation and a glass substrate, and heating and pressurization (170°C, 20 MPa, 10 seconds) was performed, thereby producing a connection structure for evaluation, and the initial conductive resistance thereof was measured, and evaluation was performed in accordance with the following conductivity evaluation criteria. The results obtained are shown in Table 1. In terms of practical use, A or B evaluation is required for conductivity.

[0145] Here, the terminal (bump) patterns of the IC for evaluation and the glass substrate correspond to each other, and the dimensions are as described below. Furthermore, when the IC for evaluation and the glass substrate are connected, the long dimension direction of the anisotropic conductive film is made to coincide with the short dimension direction of the bumps.

[0146] IC for conductivity evaluation

[0147] Outer dimensions: 1.8 x 20.0 mm.

[0148] Thickness: 0.5 mm.

[0149] Bump specifications: 30 pm wide x 85 pm long, bump pitch 50 pm, bump height 15 pm.

[0150] Glass substrate (Ti / Al wiring)

[0151] Glass material: 1737F manufactured by Corning Incorporated.

[0152] Outer dimensions: 30 x 50 mm.

[0153] Thickness: 0.5 mm.

[0154] Conductivity evaluation

[0155] Rank: Criteria.

[0156] A: Initial on-resistance is less than 1.0 Ω.

[0157] B: Initial on-resistance is 1.0 Ω or more and less than 2.0 Ω.

[0158] C: Initial on-resistance is 2.0 Ω or more and less than 4.0 Ω.

[0159] D: Initial on-resistance is 4.0 Ω or more.

[0160] [Table 1]

[0161]

[0162] <Discussion of Results>

[0163] As for each of the anisotropic conductive films and the connection structures of Examples 1 to 3, which are filler-containing films, each evaluation item for immobility, indentation, and on-conductivity showed a result that was not practically problematic.

[0164] (Reference Examples 1 to 3)

[0165] Note that the filler-containing film of Reference Example 1 in which only the opening diameter of the through-hole formed in the core film in Example 1 was changed to 3.60 μm, the filler-containing film of Reference Example 2 in which only the opening diameter of the through-hole formed in the core film in Example 1 was changed to 3.40 μm, and the filler-containing film of Reference Example 3 in which only the thickness of the core film in Example 1 was changed to 3.40 μm were produced.

[0166] Evaluation was performed on the produced filler-containing films in the same manner as in Example 1, and as a result, in the filler-containing film of Reference Example 1, the indentation was the same, but the on-conductivity was evaluated as D. In the filler-containing film of Reference Example 2, the indentation was worse, and the on-conductivity was also evaluated as D. From these results of Reference Examples 1 and 2, it was inferred that, in the case where the opening diameter of the through-hole was not large enough, the remaining space in which the filler deformed when being pressed in was insufficient. Further, the filler-containing film of Reference Example 3 also showed the same result as that of Reference Example 2. It was inferred that the reason for this was that, because the average particle diameter of the filler was the same as the thickness of the core film, the filler could not be sufficiently pressed in.

[0167] Industrial Applicability

[0168] In the filler-containing film of the present application, the relationships among the "core film thickness", "filler particle diameter", and "through-hole opening diameter" are defined as specific mutual relationships. Thus, when two members are joined by pressure bonding, such as heat pressure bonding, etc., with the filler-containing film interposed therebetween, the resin flow of the core film can be suppressed, the unintended movement of the filler can be limited, good particle capturing properties can be achieved, and, in the case where the filler-containing film is applied to a conductive film or an anisotropic conductive film, good pressure marks can be obtained, and good conduction properties can be achieved between the connected electrodes. Thus, the filler-containing film of the present application is useful when connecting various electronic parts to a substrate.

[0169] BRIEF DESCRIPTION OF DRAWINGS

[0170] 1: Insulating base layer; 2: Adhesive layer; 3: Core film; 4: Filler; 10: Filler-containing film; 20: Release substrate; th: Through-hole; P d : Average particle diameter of filler; O d : Opening diameter of through-hole; C t : Thickness of core film.

Claims

1. A filler-containing film, wherein: The filler-containing film has a core film with through holes sandwiched between the insulating base layer and the adhesive layer, and the filler is retained in the through holes. And the filler-containing film satisfies the following formulas (1) and (2): O d ≥2×P d -C t (1) 0.9×P d ≥C t (2) 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.

2. The filler-containing film according to claim 1, wherein The filler-containing film satisfies the following formulas (1') and (2'): 2×P d ≥O d ≥2×P d -C t (1’) 0.9×P d ≥C t ≥0.3×P d (2’)。 3. The filler-containing film according to claim 1 or 2, wherein The through holes are arranged regularly.

4. 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.

5. A conjugate, wherein: The bonded body is a bonded body obtained by bonding a first member and a second member via the filler-containing film according to claim 1 .

6. A connection structure, wherein: The connection structure is obtained by conductively connecting a first electronic component to a second electronic component or anisotropically conductively connecting the filler-containing film according to claim 4 as a conductive film or an anisotropic conductive film.

7. A method for producing a joined body, wherein: After the filler-containing film according to claim 1 is disposed between the first member and the second member, the first member and the second member are bonded together.

8. A method for manufacturing a connection structure, wherein: By using the filler-containing film according to claim 4 as a conductive film or an anisotropic conductive film, a first electronic component is conductively connected or anisotropically conductively connected to a second electronic component.

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

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