Filler-containing membrane, connection structure, and method for producing same

Abstract

Provided is a filler-containing film having a structure in which a first insulating layer, an intermediate layer, and a second insulating layer are laminated in this order, said filler-containing film having a novel configuration in which, when the filler-containing film is used as an anisotropic conductive film, unnecessary movement of a filler such as conductive particles during anisotropic conductive connection can be suppressed, and the thickness of the filler-containing film can be reduced. The present invention does not cause a disorder in the regular arrangement state of a filler and does not cause a reduction in conductivity. The first insulating layer has a first recess on the intermediate layer side, the intermediate layer has a second recess having a side wall portion and a bottom cover portion, the second recess is embedded in the first recess of the first insulating layer, and the filler is held in the second recess. The thickness of the bottom cover portion of the second recessed portion of the intermediate layer is 0.5 times or less of the average particle diameter of the filler.

Description

Technical Field

[0001] The present invention relates to films containing fillers. 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 to an article, the resin forming the filler-containing film is suppressed from flowing unnecessarily during thermocompression bonding, thereby suppressing the bias of the filler, which is ideal from the perspective of optical, mechanical, or electrical properties. In particular, when a filler-containing film is used as a conductive film or an anisotropic conductive film for mounting electronic components, if the conductive particles are dispersed at a high density in the insulating resin layer in order to cope with high-density mounting of electronic components, the excessive resin flow during mounting of the electronic components causes the conductive particles to move unnecessarily and be biased between the terminals, thus causing a short circuit. Therefore, it is required to suppress the unnecessary movement of such conductive particles.

[0003] In response to such demands, an anisotropic conductive film has been proposed, which is obtained by laminating an insulating film having regularly arranged through-holes on an adhesive layer, filling the through-holes with conductive particles, and then laminating another adhesive layer (Patent Document 5).

[0004] Prior art literature

[0005] Patent Literature

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

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

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

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

[0010] Patent Document 5: Japanese Patent Application Laid-Open No. 2018-174069 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] However, the anisotropic conductive film of Patent Document 5 has the following problem: if excessive resin flow occurs during anisotropic conductive connection, the conductive particles filling the through-holes of the insulating film may undesirably move from one of the pair of openings of the through-holes to the outside of the through-holes, disrupting the regular arrangement of the conductive particles and reducing the conductivity during the anisotropic conductive connection. The same problem may also occur when two components are connected by compression bonding, such as thermocompression bonding, via a filler-containing film, wherein a core film having through-holes is sandwiched between an insulating base layer and an adhesive layer, with the filler retained in the through-holes.

[0013] The object of the present invention is to solve the above-mentioned problems of the prior art, and the object is to solve the problems when two components are connected by crimping, such as hot crimping, via a filler-containing film, wherein the filler-containing film has a core film having through holes for retaining the filler sandwiched between an insulating base layer and an adhesive layer. The present invention provides a filler-containing film of a novel structure, which suppresses unnecessary movement of fillers such as conductive particles during crimping such as conductive connection or anisotropic conductive connection, and does not disrupt the regular arrangement state of the filler. When used as a conductive film or anisotropic conductive film, the conductivity during conductive connection or anisotropic conductive connection is not reduced.

[0014] Solutions for solving problems

[0015] The present inventors have discovered that, for a filler-containing film having a structure in which an intermediate layer equivalent to a core film is sandwiched between a first insulating layer equivalent to an insulating base layer and a second insulating layer equivalent to an adhesive layer, in order to retain conductive particles without providing a through-hole in the intermediate layer, it is sufficient to provide a first recess in the first insulating layer, provide a second recess embedded in the first recess in the intermediate layer, and fill and retain the filler in the second recess. At this time, in order to avoid problems when two components are connected by crimping, such as hot crimping, via the filler-containing film, it is sufficient to limit the thickness of the bottom cover portion of the second recess in the intermediate layer to a specific range at the level of its relationship with the filler, thereby completing the present invention.

[0016] Specifically, the present invention provides a filler-containing film comprising a first insulating layer, an intermediate layer, and a second insulating layer stacked in this order. The first insulating layer has a first recess on the intermediate layer side, the intermediate layer has a second recess, the second recess having a sidewall portion and a bottom cover portion, the second recess being embedded in the first recess of the first insulating layer, the filler being retained in the second recess, and the thickness of the bottom cover portion of the second recess of the intermediate layer being no greater than 0.5 times the average particle size of the filler. When conductive particles are used as the filler, the filler-containing film can be used as a conductive film or an anisotropic conductive film.

[0017] The present invention also provides a connection structure obtained by connecting a first component and a second component using the filler-containing film, preferably providing a connection structure obtained by conductively connecting or anisotropically conductively connecting a first electronic component and a second electronic component using the filler-containing film as a conductive film or an anisotropic conductive film. Furthermore, the present invention provides a method for producing a connection structure obtained by connecting a first component and a second component using the filler-containing film, preferably providing a method for producing a connection structure obtained by conductively connecting or anisotropically conductively connecting a first electronic component and a second electronic component using the filler-containing film as a conductive film or an anisotropic conductive film.

[0018] Furthermore, the present invention provides a connection method for connecting a first component and a second component using the above-mentioned filler-containing film, wherein the filler-containing film is temporarily adhered to the second component from its first insulating layer side, the first component is mounted on the temporarily adhered filler-containing film, and pressure-bonded from the first component side. Preferably, a connection method is provided for conductively connecting or anisotropically conductively connecting a first electronic component and a second electronic component using the filler-containing film used as a conductive film or an anisotropic conductive film, wherein the filler-containing film is temporarily adhered to the second electronic component from its first insulating layer side, the first electronic component is mounted on the temporarily adhered filler-containing film, and pressure-bonded from the first electronic component side.

[0019] The present invention also provides a precursor film suitable for producing the filler-containing film described above. This precursor film has a structure comprising a first insulating layer and an intermediate layer stacked together. The first insulating layer has a first recessed portion on the intermediate layer side, and the intermediate layer has a second recessed portion having sidewalls and a bottom cover portion, the second recessed portion being embedded in the first recessed portion of the first insulating layer. Filling the second recessed portion provided in the intermediate layer of the precursor film with filler using conventional methods can produce a filler-containing film.

[0020] Effects of the Invention

[0021] In the filler-containing film of the present invention having a structure in which an intermediate layer is sandwiched between a first insulating layer and a second insulating layer, a first recess is provided in the first insulating layer, a second recess embedded in the first recess is provided in the intermediate layer, and the filler is filled and retained in the second recess. Thus, the filler can be retained without providing a through hole in the intermediate layer. Moreover, the thickness of the bottom cover portion of the second recess of the intermediate layer is limited to be thinner than the thickness of the first insulating layer and the second insulating layer and less than 0.5 times the average particle size of the filler. Therefore, the problem of connecting two components by crimping, such as thermocompression bonding, via a filler-containing film can be avoided (i.e., the problem of insufficiently suppressing excessive resin flow, resulting in unnecessary movement of the filler, disorder of the regular arrangement state of the filler, and reduced conductivity during conductive connection or anisotropic conductive connection when used as a conductive film or anisotropic conductive film). BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 1B yes Figure 1A A partial enlarged cross-sectional view of a membrane containing filler.

[0024] Figure 2A It is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0025] Figure 2B It is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0026] Figure 2C This is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0027] Figure 2D It is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0028] Figure 2E It is an explanatory diagram of the method for producing the filler-containing film of the present invention.

[0029] Figure 2F It is an explanatory diagram of the method for producing the filler-containing film of the present invention. DETAILED DESCRIPTION

[0030] Hereinafter, an example of the filler-containing film of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or equivalent components.

[0031] <Overall structure of filler-containing film>

[0032] Figure 1A 1 is a cross-sectional view of a filler-containing film 10 of the present invention. The filler-containing film 10 has a structure in which a first insulating layer 1, an intermediate layer 2, and a second insulating layer 3 are sequentially stacked. Figure 1B As shown, the first insulating layer 1 has a first recess 4 on the intermediate layer 2 side. Furthermore, the intermediate layer 2 has a second recess 5, which has a sidewall portion 5a and a bottom cover portion 5b. This second recess 5 is embedded in the first recess 4 of the first insulating layer 1. In other words, it is provided so as to cover the inner surface of the first recess 4 of the first insulating layer 1. Filler 6 is retained in the second recess 5. Furthermore, the thickness of the bottom cover portion 5b of the second recess 5 of the intermediate layer 2 is no greater than 0.5 times the average particle size of the filler 6. Each component of the filler-containing film 10 is described in detail below.

[0033] <First Insulating Layer 1>

[0034] The first insulating layer 1 constituting the filler-containing film 10 of the present invention serves as a base layer for forming an intermediate layer thereon during the production of the filler-containing film 10. Such a first insulating layer 1 may be composed of a single insulating resin layer or a laminate of multiple insulating resin layers. Furthermore, the first insulating layer 1 preferably exhibits adhesiveness.

[0035] (Resin Composition Constituting First Insulating Layer 1)

[0036] The resin composition constituting the first insulating layer 1 can be appropriately selected according to the purpose of the filler-containing film, and examples thereof include: thermoplastic resin compositions, high-viscosity adhesive resin compositions, or curable resin compositions. When a die is used to form the first recess 4, a thermoplastic resin composition is preferred. In addition, when the filler-containing film is set as an anisotropic conductive film, a curable resin composition formed from a polymerizable compound and a polymerization initiator can be used, similar to the resin composition for forming the insulating resin layer of the conventional anisotropic conductive film. In this case, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator can be used, or a combination of these can be used. For example, a thermal cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermal polymerizable compound, a photoradical polymerization initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. As the thermal polymerization initiator, a thermal anionic polymerization initiator can be used. As the thermal anionic polymerization initiator, a microcapsule-type latent curing agent obtained by using an imidazole modified body as the core and coating its surface with polyurethane is preferably used.

[0037] (Minimum Melt Viscosity of First Insulating Layer 1)

[0038] In order to suppress unnecessary movement of filler 6 due to resin flow when the filler-containing film 10 is pressed, for example, thermally pressed, onto an article, and to guide appropriate resin flow, the minimum melt viscosity of the first insulating layer 1 may be 50 Pa·s or higher, preferably 200 Pa·s or higher, preferably 15,000 Pa·s or lower, and more preferably 8,000 Pa·s or lower. The temperature at which the minimum melt viscosity is achieved is preferably 60°C or higher, more preferably 70°C or higher, preferably 110°C or lower, and more preferably 100°C or lower. As an example, the minimum melt viscosity can be determined using a rotational rheometer (manufactured by TA Instruments) at a constant measurement pressure of 5g and a measuring plate with an 8mm diameter. More specifically, the minimum melt viscosity can be determined within a temperature range of 30-200°C, with a heating rate of 10°C / minute, a measurement frequency of 10 Hz, and a load variation of 5g on the measuring plate. It should be noted that the minimum melt viscosity can be adjusted by varying the type and amount of the fine solid substance serving as the melt viscosity modifier, as well as the adjustment conditions of the resin composition.

[0039] (Thickness of the First Insulating Layer 1)

[0040] To stably maintain the interlayer 2 and filler 6, the thickness of the first insulating layer 1 is preferably at least 0.6 times the average particle size of the filler 6, more preferably at least 1.2 times, and particularly preferably at least 1.5 times. The upper limit of the thickness of the first insulating layer 1 varies depending on the method of use, but when sandwiching two surfaces of the film, to avoid unnecessary movement of the filler 6 due to resin flow, the thickness is preferably no greater than 10 times, and more preferably no greater than 5 times, the average particle size of the filler 6. The layer thickness can be measured using a known thickness gauge or film thickness measuring instrument.

[0041] (Adhesion of the First Insulating Layer 1)

[0042] The first insulating layer 1 preferably has an adhesive strength that enables temporary pressing before pressing an article to be pressed, for example, hot-pressed, to a film containing a filler. The adhesive strength can be measured in accordance with JIS Z 0237, and can also be measured by a probe method in accordance with JIS Z 3284-3 or ASTM D 2979-01. The adhesive strength of the first insulating layer 1 constituting the film 10 containing a filler based on the probe method is preferably 1.0 kPa (0.1 N / cm2) when measured at a probe pressing speed of 30 mm / min, a pressure of 196.25 gf, a pressing time of 1.0 sec, a peeling speed of 120 mm / min, and a measuring temperature of 23°C ± 5°C. 2 More preferably, it is 1.5 kPa (0.15 N / cm 2 ) or more, particularly preferably 3.0 kPa (0.3 N / cm2 )above.

[0043] In addition, the adhesive force of the filler-containing film can also be determined based on the adhesive strength test described in Japanese Patent Application Publication No. 2017-48358. In this adhesive strength test, for example, when the filler-containing film 10 is clamped between two glass plates, one glass plate is fixed, and the other glass plate is peeled at a peeling speed of 10 mm / min and a test temperature of 50°C, the adhesive force between the glass plate to be peeled and the surface of the filler-containing film bonded to the glass plate can be measured by pre-enhancing the bonding state between the fixed glass plate and the filler-containing film. The adhesive strength (adhesive force) 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 existing in the peeling direction and the peeled object.

[0044] 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, 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 (10kPa) or more). If the adhesive strength based on the above-mentioned adhesive strength test is large enough (for example, 10N / cm 2 (100 kPa) or more), the adhesive force in this test method may be 10% or more of the adhesive force based on the above-mentioned adhesive strength test.

[0045] Such adhesive force can be adjusted by appropriately adjusting the resin composition constituting the first insulating layer 1 and improving the smoothness of the first insulating layer 1 serving as the outer surface of the filler-containing film by a method for producing the filler-containing film described later.

[0046] (First recess 4 provided in first insulating layer 1)

[0047] In the present invention, the first insulating layer 1 is provided with a first recess 4 on the side of the intermediate layer 2. This first recess 4 receives and supports the second recess 5 formed in the intermediate layer 2, and has the function of indirectly retaining the filler 6 held in the second recess 5. To ensure good adhesion of the filler-containing film 10 to other components, the surface of the first insulating layer 1 without the first recess 4 is preferably flat.

[0048] In order to indirectly and reliably retain the filler 6 held in the second recess 5, the first recess 4 is preferably a cylindrical, tumbler, or cup-shaped hole. To ensure the immobility of the filler, the first recess 4 preferably has a uniform diameter from the opening toward the bottom, but may also have a tapered shape where the diameter decreases toward the bottom.

[0049] The first recess 4 can be randomly arranged in the first insulating layer 1, and is preferably arranged in a regular arrangement pattern for the sake of the capture stability of the filler (for example, when the film containing the filler is a conductive film, the particle capture stability in the electrode). The configuration pattern of the first recess 4 is not only substantially synonymous with the second recess 5 of the intermediate layer 2 in the film 10 containing the filler, but also substantially synonymous with the presence pattern of the filler 6. As examples of regular patterns, lattice configurations such as square lattices, rectangular lattices, and rhombus lattices can be listed. Multiple lattices of different shapes can also be combined. It is also possible to arrange the first recess rows in which the first recesses 4 are arranged in a straight line at specified intervals at specified intervals. The areas where the first recesses 4 are densely arranged and the areas where they are sparsely arranged can also be regularly repeated. In the case where the film 10 containing the filler is set as a conductive film or an anisotropic conductive film, in order to take into account both the capture stability and short circuit suppression in the terminal, it is more preferred to set the first recesses 4 as a regular configuration separated from each other. Whether the first recesses 4 are regularly arranged can be determined by, for example, observing whether the predetermined arrangement of the first recesses or fillers is repeated in the longitudinal direction of the film (the direction in which the filler-containing film is wound into a package).

[0050] It should be noted that the center-to-center distance and number density of the first recesses 4 are the same as the center-to-center distance and number density of the second recesses 5 embedded in the first recesses 4. In addition, the depth of the first recess 4 ( Figure 1B The first concave depth h) and its opening diameter (the second concave bottom cover outer diameter d) depend on Figure 1B The shape of the second recess 5 is shown. These aspects will be described later in relation to the second recess 5.

[0051] <Middle layer 2>

[0052] The intermediate layer 2 constituting the filler-containing film 10 of the present invention has a second recess 5 for retaining the filler 6. This layer serves to suppress unintended movement of the filler 6 caused by resin flow in the first insulating layer 1 and the second insulating layer 3, and thus functions as a spacer. Such an intermediate layer 2 may be composed of a single insulating resin layer or a laminate of multiple insulating resin layers.

[0053] (Resin Composition Constituting Intermediate Layer 2)

[0054] The resin composition constituting the intermediate layer 2 can be appropriately selected depending on the intended use of the filler-containing film 10. Examples thereof include thermoplastic resin compositions such as phenoxy, polyimide, polyamide, polyacetal, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyvinyl acetate; high-viscosity adhesive resin compositions; and curable resin compositions such as epoxy and acrylic resins, or mixtures thereof. When forming the second recess 5 using a press mold, a thermoplastic resin composition is preferred.

[0055] (Melt viscosity of intermediate layer 2)

[0056] In order to suppress the unnecessary movement of the filler 6 caused by the flow of the resin when the filler-containing film 10 is pressed, for example, hot-pressed, to an article, the melt viscosity of the intermediate layer 2 is preferably 1.1 times or more, and more preferably 1.2 times or more, the lowest melt viscosity of the first insulating layer 1 in the temperature range during pressing. As an example, a rotational rheometer (manufactured by TA Instruments) can be used to determine the melt viscosity by maintaining a constant measurement pressure of 5 g and using a measurement plate with a diameter of 8 mm. More specifically, the melt viscosity can be determined by setting the temperature range to 30-250°C, setting the heating rate to 10°C / min, the measurement frequency to 10 Hz, and the load variation of the measurement plate to 5 g. It should be noted that the adjustment of the melt viscosity can be carried out by changing the type and amount of the fine solid substance used as the melt viscosity modifier, the adjustment conditions of the resin composition, etc.

[0057] (Thickness of the intermediate layer 2)

[0058] In order to stably maintain the filler 6 and other conditions, the thickness of the intermediate layer 2 ( Figure 1B The thickness a) of the intermediate layer can be 0.6 times or more, preferably 1.2 times or more, and more preferably 1.5 times or more of the average particle size of the filler 6. In addition, the upper limit of the thickness a of the intermediate layer varies according to the method of use, but in the case of clamping the two sides of the film, in order to avoid unnecessary movement of the filler 6 due to the flow of the resin, it is preferably 10 times or less, and more preferably 5 times or less, of the average particle size of the filler 6. The layer thickness can be measured by a known thickness gauge or film thickness measuring instrument. It should be noted that the average particle size of the filler can be obtained based on a top view image or a cross-sectional image. In addition, the average particle size of the filler as the raw material particles before being contained in the film containing the filler can also be obtained using a wet flow type particle size / shape analyzer FPIA-3000 (Malvern Panalytical). It should be noted that when particles such as insulating particles are attached to the filler, the diameter without the particles is taken as the particle size.

[0059] (Second recess 5 provided in the intermediate layer 2)

[0060] A second recess 5 for filling and retaining the filler 6 is provided in the intermediate layer 2. The second recess 5 opens on the side of the second insulating layer 3. In order to reliably retain the filler 6, the second recess 5 is preferably a hole in the shape of a cylinder, an open cylinder or a cup. The shape of the opening is not limited to a circle, and may also be a rectangle or a diamond. In addition, there may be a scheme in which only the cup-shaped second recess 5 is buried in the first insulating layer 1, but in the case of this scheme, the thickness a of the intermediate layer is 0. It can be selected according to the purpose of the filler to be accommodated. It should be noted that the first recess 4 preferably has the same pore diameter from the opening to the bottom for the immobility of the filler, and may also have a tapered shape in which the pore diameter becomes smaller toward the bottom according to the shape of the second recess 5. By having such a tapered shape, the retention of the filler is improved.

[0061] Such a second recess 5 can be arranged in the middle layer 2 in a random configuration pattern, and is preferably arranged in a regular configuration pattern for the sake of the capture stability of the filler. The configuration pattern of the second recess 5 is essentially synonymous with the presence pattern of the filler 6 in the film 10 containing the filler. As examples of regular configuration patterns, lattice arrangements such as square lattices, rectangular lattices, and rhombus lattices can be cited. Grids of different shapes can also be combined in multiple ways. It is also possible to arrange the second recess rows in which the second recesses 5 are arranged in a straight line at prescribed intervals at prescribed intervals. The areas where the second recesses 5 are densely configured and the areas where they are sparsely configured can also be repeated regularly. In the case where the film 10 containing the filler is set as an anisotropic conductive film, in order to take into account both the capture stability and short circuit suppression in the terminal, it is more preferable to set the second recess 5 as a regular arrangement separated from each other. It should be noted that whether the second recess 5 is regularly configured can be judged by observing whether the prescribed configuration of the second recess 5 or the filler 6 is repeated in the long dimension direction of the film (the winding direction when the film containing the filler is made into a roll).

[0062] The distance between the second recesses 5 can be determined according to the connected items and the purpose. The number density of the second recesses 5 is usually 10 / mm. 2 More than 30 pieces / mm is preferred 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 determined by measuring the field of view of the film surface under microscope observation. The observation area during microscope observation is 2mm 2 Above, preferably 10mm 2 above.

[0063] The number density of the second recesses 5 (i.e., the filler 6) can be determined not only by observing with a metallurgical microscope but also by measuring and observing an image using image analysis software (e.g., WinROOF (Mitsutani Shoko Co., Ltd.), Azokun (A-kun) (registered trademark) (Asahi Kasei Engineering Co., Ltd.), etc.). The observation method and the measurement method are not limited to the above methods.

[0064] In the present invention, by unifying the sizes of the first recesses and the second recesses, respectively, the effects of the invention can be more significantly exhibited. For this reason, it is desirable that the sizes and depths of the openings of the first recesses and the second recesses satisfy the following conditions. That is, in the film containing the filler, it is desirable that the total observed area is 1 mm 2 or more, preferably 2 mm 2 or more, and in a region where the number of recesses is 1000 or more (preferably 2000 or more), 95% or more, preferably 98% or more, more preferably 99.5% or more of the total number of recesses have the same size and depth of the openings. Here, "the same size and depth of the openings" means that the sizes and depths of the openings of a certain first recess and a second recess are within ±15%, preferably within ±10%, more preferably within ±5% of the average size and average depth of the openings of the recesses included in their respective specified regions, taking into account measurement errors. It should be noted that there are openings with different shapes of the openings, so the size of the openings can also be set as the diameter when the area of the openings is converted into a circle.

[0065] The shape of such a second recess 5 can be preferably as Figure 1B shown, and is determined by the intermediate layer thickness a, the second recess opening diameter b, the second recess bottom cover diameter c, the second recess bottom cover outer diameter d, the second recess depth e, the second recess bottom cover thickness f, and the second recess side wall thickness g. In the film 10 containing the filler of the present invention, the second recess bottom cover thickness f becomes a problem. This is because if the second recess bottom cover thickness f is too thick, although unnecessary movement of the filler can be suppressed, on the other hand, it is difficult to remove the intermediate layer under the filler when connecting with the first member and the second member, and it may be difficult to obtain a good connection state.

[0066] Therefore, the second recess bottom cover thickness f is 0.5 times or less, preferably 0.4 times or less of the average particle diameter of the filler 6. Here, the reason for defining the upper limit of the second recess bottom cover thickness f with the average particle diameter of the filler 6 as an index is that in order to conduct the connection, the filler needs to penetrate the intermediate layer. For example, in the case of using small fillers, the second recess bottom cover thickness f needs to be thin. If the particles become larger, compared with the case of using small particle size fillers, the second recess bottom cover thickness f can be thickened, and the immobility of the filler can be further controlled.

[0067] It should be noted that if the thickness f of the second recess bottom cover is too thin (the final thickness is zero (in other words, if the second recess 5 serves as a through-hole in the intermediate layer 2)), when the first and second components are connected using the filler-containing film 10 by compression bonding, such as thermocompression bonding (for example, in anisotropic conductive bonding), resin can easily flow from the upper and lower openings of the through-hole in the intermediate layer to the outside of the intermediate layer. As a result, the filler retained in the through-hole may be unnecessarily moved, potentially disrupting the regular arrangement of the filler. In particular, when the filler-containing film is used as a conductive film or an anisotropic conductive film, there is a possibility of reduced conductivity during connection. Therefore, the thickness f of the second recess bottom cover can be as thick as can be observed using an electron microscope (SEM), preferably 50 nm or more, and more preferably 100 nm or more.

[0068] The thickness f of the second concave bottom cover is controlled by adjusting the thickness a of the intermediate layer. If more detailed control is desired, control can also be achieved by appropriately adjusting the coating conditions when forming the intermediate layer by dissolving the intermediate layer resin composition in an organic solvent and applying the resultant material to a convex mold and pressing it onto the second insulating layer.

[0069] In addition, if the thickness of the side wall portion 5a of the second recess 5 ( Figure 1B If the thickness g of the second recessed portion sidewall is too thin, cracking of the intermediate layer 2 may cause a decrease in filler immobility. Therefore, it is preferably 50 nm or greater, more preferably 100 nm or greater, and preferably 0.5 times or less, and more preferably 0.4 times or less, the average particle size of the filler 6. The thickness g of the second recessed portion sidewall can be controlled by the same method as for the bottom cover portion, or by using a convex taper or the like.

[0070] In addition, from the viewpoint of easily retaining the filler, the depth of the second recess 5 provided in the intermediate layer 2 ( Figure 1B The second recess depth e) is preferably at least 0.2 times the average particle size of the filler 6, and more preferably at least 0.5 times. Consequently, the depth of the second recess 5 is greater than the second recess bottom thickness f. It should be noted that, from the perspective of accommodating and retaining a single filler 6 within a single recess, the depth of the second recess 5 is preferably no more than 2 times the average particle size of the filler 6, and more preferably no more than 1.3 times.

[0071] It should be noted that, from the perspective of the shape stability of the second recess 5, and from the perspective of ensuring the wall thickness and preventing peeling of the intermediate layer 2, the ratio of the first recess depth h of the first recess 4 to the total thickness (e+f) of the second recess depth e of the second recess 5 and the second recess bottom cover thickness f is preferably 55% or more, more preferably 60% or more, preferably 95% or less, more preferably 90% or less, and further preferably 80% or less.

[0072] The second recess opening diameter b of the second recess 5 varies depending on the size of the filler 6 described later, but is preferably 1.0 times or more, more preferably 1.2 times or more, the average particle size of the filler 6 from the perspective of easy filler retention. From the perspective of easy filler accommodation, the upper limit is preferably 3.0 times or less, more preferably 2.0 times or less, and particularly preferably 1.5 times or less, the average particle size of the filler 6.

[0073] To ensure filler accommodation, the second recess bottom cover diameter c of the second recess 5 is preferably the same as or larger than the second recess opening diameter b. To ensure filler immobility, it may also be smaller than the second recess opening diameter b. The second recess bottom cover diameter c is preferably at least 0.8 times the average particle size of the filler 6, and more preferably at least 1.0 times. If it is too large compared to the average particle size of the filler 6, either accommodation or immobility may be compromised. Therefore, it is preferably less than twice the average particle size of the filler 6, and more preferably less than 1.5 times.

[0074] The filler filling rate of the second recess 5 can be calculated as {(the number of fillers / the number of recesses) × 100 (%)}. This can be calculated by observing the film surface field of view in the same way as the number density of the second recesses 5. The filler filling rate can 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 second recess 5 is small (close to zero). In practical applications, the residual rate can be less than 2%, preferably less than 1%, and more preferably less than 0.5% relative to the number of second recesses 5. 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 the film surface to be damaged.

[0075] <Second Insulating Layer 3>

[0076] The second insulating layer 3 constituting the filler-containing film 10 of the present invention is a layer for temporarily crimping the filler-containing film 10 to an article. Such a second insulating layer 3 may be composed of a single insulating resin layer or a laminate of multiple insulating resin layers.

[0077] (Resin Composition Constituting Second Insulating Layer 3)

[0078] The resin composition constituting the second insulating layer 3 is appropriately selected according to the purpose of the filler-containing film, as with the first insulating layer 1, and examples thereof include thermoplastic resin compositions, high-viscosity adhesive resin compositions, or curable resin compositions. For example, when the filler-containing film is set as an anisotropic conductive film, a curable resin composition composed of a polymerizable compound and a polymerization initiator can be used, similar to the resin composition for forming the adhesive layer of the conventional anisotropic conductive film. In this case, as the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator can be used, or a combination of these can be used. For example, a thermal cationic polymerization initiator is used as the thermal polymerization initiator, an epoxy resin is used as the thermal polymerizable compound, a photoradical polymerization initiator is used as the photopolymerization initiator, and an acrylate compound is used as the photopolymerizable compound. As the thermal polymerization initiator, a thermal anionic polymerization initiator can be used. As the thermal anionic polymerization initiator, a microcapsule-type latent curing agent having an imidazole modified body as the core and its surface coated with polyurethane is preferably used.

[0079] (Minimum Melt Viscosity of Second Insulating Layer 3)

[0080] The minimum melt viscosity of the second insulating layer 3 can be the same as that of the first insulating layer 1 described above. It can be intentionally set lower or higher than that of the first insulating layer 1. Adjusting the minimum melt viscosity (and thickness) of the first and second insulating layers 1 and 3 allows for precise control of resin flow when the filler-containing film 10 is pressed, for example, thermally pressed, onto an article, leading to promising applications in a variety of applications. When used for anisotropic conductive connections, it allows for even more precise control of unwanted movement of the filler conductive particles.

[0081] (Thickness of the Second Insulating Layer 3)

[0082] The thickness of the second insulating layer 3 may be the same as that of the first insulating layer 1. It may be intentionally set to be thinner than the first insulating layer 1, or it may be set to be thicker than the first insulating layer 1. Specifically, it is preferably 0.1 μm or more, and more preferably 0.5 μm or more. When used for pasting, it is preferably set to be thin. In order to fill between the parts to be joined, it may also be set to be 20 μm or more. If it is too thick, there is a concern that the resin will overflow when it is made into a package, so it is preferably 50 μm or less. In this way, the upper limit can be appropriately set according to the purpose.

[0083] (Adhesion of the Second Insulating Layer 3)

[0084] The second insulating layer 3 preferably has sufficient adhesive strength to temporarily adhere to an article that is being crimped, for example, by heat-compression bonding of a filler-containing film (as long as it has sufficient adhesive strength to adhere to the article). The adhesive strength of the second insulating layer 3 can be the same as that of the first insulating layer 1, or stronger than, or weaker than, the first insulating layer 1. The adhesive strength of the second insulating layer 3 and the adhesive strength of the first insulating layer 1 can be optimized separately, taking into account whether the surface being attached to the article is the first insulating layer 1 or the second insulating layer 3, and the degree of adhesive strength required for the article being placed.

[0085] Such adhesive force can be adjusted by appropriately adjusting the resin composition constituting the second insulating layer 3 and improving the smoothness of the second insulating layer 3 serving as the outer surface of the filler-containing film by a method for producing the filler-containing film described later.

[0086] <Padding 6>

[0087] In the present invention, filler 6 can be appropriately selected from the following fillers, depending on the application of the filler-containing film and the properties required for the application, such as hardness and optical properties: known inorganic fillers (metal particles, metal oxide particles, metal nitride particles, etc.), organic fillers (resin particles, rubber particles, etc.), and fillers containing a mixture of organic and inorganic materials (for example, particles having a resin core and a metal-plated surface (metal-coated resin particles), fillers having insulating fine particles attached to the surface of conductive particles, and fillers having an insulating treatment applied to the surface of conductive particles). For example, silica fillers, titanium oxide fillers, styrene fillers, acrylic fillers, melamine fillers, and various titanates can be used in optical films and matte films. For capacitor films, titanium oxide fillers, magnesium titanate fillers, zinc titanate fillers, bismuth titanate fillers, lanthanum oxide fillers, calcium titanate fillers, strontium titanate fillers, barium titanate fillers, barium zirconate titanate fillers, lead zirconate titanate fillers, and mixed fillers thereof can be used. The adhesive film can contain polymer-based rubber particles, silicone rubber particles, and the like. Conductive particles are contained in the conductive film or anisotropic conductive film. Examples of the conductive particles include metal particles such as nickel, cobalt, silver, copper, gold, and palladium, alloy particles such as solder, metal-coated resin particles, and metal-coated resin particles with insulating particles attached to the surface. Two or more types of conductive particles may also be used in combination. Metal-coated resin particles are preferred because they repel the resin particles after connection, making it easier to maintain contact with the terminal and ensuring stable conductive performance. Furthermore, the surface of the conductive particles may be subjected to an insulating treatment that does not hinder the conductive properties using known techniques.

[0088] (Average particle size of filler 6)

[0089] In the present invention, the average particle size of the filler 6 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, the average particle size of the filler is preferably 1 μm or more, more preferably 2.5 μm or more. In addition, in order to suppress the influence of the positional offset of the filler during the manufacture of the filler-containing film, the average particle size of the filler is preferably 200 μm or less, more preferably 50 μm or less. The average particle size of the filler can be obtained based on a top view image or a cross-sectional image. In addition, the average particle size of the filler as the raw material particles before being contained in the filler-containing film can also be obtained using a wet flow type particle size / shape analyzer FPIA-3000 (Malvern Panalytical). It should be noted that when particles such as insulating particles are attached to the filler, the diameter without the particles is set as the particle size.

[0090] Regarding the deviation of the average particle size of the filler 6 in the filler-containing film 10, it is preferred that the CV value (standard deviation / average) be set to 20% or less. Thus, when the filler-containing film is pressed against an article, the filler-containing film is easily pressed evenly, which can prevent the pressing force from being concentrated locally. Therefore, when the filler-containing film is constructed as a conductive film or an anisotropic conductive film, the stability of the connection is improved. In addition, after the connection, the connection state can be accurately evaluated by observing the indentation and 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, whether the terminal size is large (FOB (Flex On Board) etc.) or relatively small (COG (Chip On Glass) etc.), the connection state can be accurately confirmed by observing the indentation and the clamping state of the conductive particles. Therefore, the inspection after the conductive connection or anisotropic conductive connection becomes easy, and it can be expected to improve the productivity of the connection process.

[0091] 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 coplanar with the surface parallel to the interface between the intermediate layer 2 and the second insulating layer 3. This makes it easy to uniformly press-bond the filler-containing film to the article.

[0092] <Method for producing filler-containing film>

[0093] The filler-containing film of the present invention can be produced, for example, by preparing a filler-containing film precursor film as follows (see Figure 2D ), and fillers are filled in the concave parts of the intermediate layer of the obtained precursor film using conventional methods to manufacture it.

[0094] <Example of Production of Precursor Film of Filler-Containing Film>

[0095] 1. Prepare a convex mold, apply a resin composition for forming an intermediate layer on the mold and dry it to form an intermediate layer, and press-bond a first insulating layer film on the formed intermediate layer, or apply a composition for forming a first insulating layer and dry it, and then peel it from the mold, thereby obtaining a precursor film of a film containing a filler.

[0096] 2. The intermediate layer-forming resin composition is applied to a flat plate, pressed against a convex mold, and dried to form an intermediate layer. The formed intermediate layer is attached to the first insulating layer film and then peeled from the mold to obtain a precursor film of a filler-containing film.

[0097] 3. The resin composition for forming the intermediate layer is applied to a flat plate and dried to form an intermediate layer. A convex mold is pressed against the formed intermediate layer while the intermediate layer is molten, and the first insulating layer film is attached and then peeled off from the mold to obtain a precursor film of a film containing a filler.

[0098] The precursor film obtained as described above is suitable for production of a filler-containing film in which a first insulating layer, an intermediate layer, and a second insulating layer are sequentially laminated, and is one embodiment of the present invention.

[0099] The precursor film has a structure in which a first insulating layer and an intermediate layer are stacked, the first insulating layer has a first recess on the intermediate layer side, and the intermediate layer has the following structure: a second recess having a sidewall portion and a bottom cover portion, and the second recess is embedded in the first recess of the first insulating layer.

[0100] Regarding the first insulating layer, first recess, intermediate layer and second recess constituting the precursor, as described in the filler-containing film of the present invention, in order to fill the filler, it is particularly preferred that the thickness of the bottom cover portion of the second recess is greater than 0.8 times and less than 1.5 times the opening diameter of the second recess.

[0101] A specific example of manufacturing the filler-containing film of the present invention is shown in Figures 2A to 2F The present invention is not limited to this manufacturing method.

[0102] First, if Figure 2A As shown, the first insulating layer 21 is formed on the release film RF. The first insulating layer 21 can be formed by, for example, applying a first insulating layer-forming composition on the release film RF by a conventional method and drying the coating.

[0103] Then, if Figure 2B As shown, the intermediate layer 22 is formed on the first insulating layer 21. Thus, a laminate consisting of the release film RF / first insulating layer 21 / intermediate layer 22 is obtained. The intermediate layer 22 can be formed by, for example, applying an intermediate layer forming composition on the first insulating layer 21 and drying it.

[0104] Then, if Figure 2C As shown, the obtained laminate is placed on a metal flat plate MB such as stainless steel from the release film RF side and is pressed using a separately prepared press mold PM having convex portions corresponding to the second concave portions.

[0105] After that, if the stamper PM is removed, Figure 2D As shown, a first recess 24 is formed in the first insulating layer 21 , and a second recess 25 having a side wall portion 25 a and a bottom cover portion 25 b is formed in the intermediate layer 22 .

[0106] Then, if Figure 2E As shown, the second recesses 25 of the intermediate layer 22 of the laminate are filled with a filler 26. The filling of the second recesses 25 with the filler 26 can be performed by, for example, spreading the filler 26 on the surface of the intermediate layer 22 and applying it by a doctor blade.

[0107] Then, if Figure 2F As shown, the filler-containing film 20 of the present invention can be manufactured by forming the second insulating layer 23 on the intermediate layer 22 holding the filler 26 in the second recess 25. The second insulating layer 23 on the intermediate layer 22 can be formed by applying a second insulating layer-forming composition on the intermediate layer 22 and drying it.

[0108] How to use filler-containing films

[0109] The filler-containing film of the present invention can be applied to an article for use in the same manner as conventional filler-containing films, and there is no particular restriction on the article to be applied. Therefore, a connection structure in which a first component and a second component are connected via a filler-containing film, and a method for manufacturing a connection structure by arranging a filler-containing film between the first component and the second component and connecting 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 make a conductive connection or an anisotropic conductive connection between a first electronic component and a second electronic component. In addition, the filler-containing film can also be used for electronic components for purposes other than conductive connection and anisotropic conductive connection, wherein the first electronic component includes: a semiconductor element using PN connection (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., and the second electronic component includes: an FPC, a glass substrate, a plastic substrate, a rigid substrate, a ceramic substrate, etc. The surface of the article to which the filler-containing film is bonded may be smooth or may have a stepped portion or a convex shape.

[0110] 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 narrow, and the mounting of the electronic components can also require high-precision alignment. For example, the bump area can be several tens of μm. 2 ~several thousand μm 2 Minimized electronic components (such as mini LEDs, micro LEDs, etc.) can be used as connection objects. On the other hand, conductive films or anisotropic conductive films can also be used to install electronic components with large external dimensions. In addition, the installed electronic components can be divided and used in small pieces. In addition, when used for large TVs, etc., a film containing fillers of more than 1 m, for example, more than 4.5 m, is sometimes adhered to one side. In this case, in addition to using the film containing fillers as a conductive film or anisotropic conductive film, it can also be used as a diaphragm to isolate the fillers, etc.

[0111] The conductive film or anisotropic conductive film of the present invention can also be used to stack IC chips and wafers to form a multilayer structure. It should be noted that the electronic components connected using the conductive film or anisotropic conductive film of the present invention are not limited to the examples of electronic components described above. In recent years, it can be used in a variety of electronic components. The present invention includes a film adherend having the filler-containing film of the present invention adhered to various articles, and particularly includes a connection structure obtained by connecting a first electronic component and a second electronic component via a conductive film or anisotropic conductive film.

[0112] The method of attaching the filler-containing film to the article can be performed by pressing according to the purpose of the filler-containing film, preferably by heat pressing, or by light irradiation during attachment. As an example of using light irradiation, it can be listed that the filler-containing film is monolithicized according to the laser lift-off method described in Japanese Patent Application Laid-Open No. 2022-151816, and then transferred. As the resin material and adhesive material to be used for making a filler-containing film suitable for the laser lift-off method, it can be selected from the materials described in Japanese Patent Application Laid-Open No. 2022-151816.

[0113] 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 typically placed on one side of a press tool, the second electronic component is placed on a workbench opposite the first electronic component, the conductive film or 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 be pre-attached to the first electronic component instead of the second electronic component. Furthermore, the first electronic component is not limited to an IC chip.

[0114] When connecting the first electronic component and the second electronic component by crimping, such as hot crimping, it is also possible to pre-exclude the resin around the conductive particles before crimping and perform temporary crimping as needed. In this way, the influence of the resin flow generated when the anisotropic conductive film is crimped to the electronic component can be reduced, and the unnecessary flow of the conductive particles can be suppressed. Specifically, when one electronic component to be connected is adhered to one surface of the conductive film or the anisotropic conductive film, and another electronic component is temporarily crimped to the other surface of the conductive film or the anisotropic conductive film, the electronic component is pressed with a press tool to partially exclude the resin between the electronic components, and then pressed as a formal crimping, for example, the electronic components are connected to each other by hot pressing (hereinafter, the connection method that performs not only pressing during formal crimping but also pressing during temporary crimping is referred to as a two-stage press-in-based connection). WO2016 / 143789 describes a connection based on two-stage press-in using an anisotropic conductive film in which conductive particles are randomly dispersed. However, 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, if such a connection based on two-stage press-in is performed, unnecessary flow of conductive particles during crimping, such as during hot crimping, can be greatly reduced.

[0115] It should be noted that the above Figure 2D The precursor film of the filler-containing film shown is most suitable for the manufacture of the filler-containing film, and is useful as a material for adjusting the mechanical properties (such as elastic modulus, scratch resistance), optical properties (such as light reflection / refractive index, light transmittance), etc. of other optical films, electronic components, etc. by laminating it itself.

[0116] Example

[0117] Hereinafter, the present invention will be described in detail.

[0118] Examples 1 to 6, Comparative Examples 1 to 2

[0119] Resin compositions for forming the first insulating layer and second insulating layer were prepared according to the formulations shown in Table 1 below. Using these resin compositions, first and second insulating layer films were produced, respectively, in the same manner as in Example 3 of Japanese Patent No. 6187665. Furthermore, a coating solution of the resin composition shown in Table 1 (diluted to a solids content of 20%) was prepared. A mold substantially similar to the mold described in paragraph 0111 of Japanese Patent No. 6187665 was then fabricated using transparent polycarbonate pellets. The intermediate layer film coating solution was then applied to the mold, followed by drying in a 60°C desiccator for 5 minutes to produce an intermediate layer film.

[0120] After the first insulating layer film was attached to the obtained intermediate layer film, it was peeled from the mold to prepare a precursor film of a filler-containing film.

[0121] As conductive particles, metal-coated resin particles (Sekisui Chemical Co., Ltd., Micropearl, average particle size 3.2 μm or 4.0 μm) were prepared. After the intermediate layer film and the first insulating layer film were stacked to form a precursor film, the concave portion of the intermediate layer of the precursor film was filled with conductive particles, and the second insulating layer film was stacked thereon to prepare a film containing filler. The stacking of the films and the filling of the conductive particles were carried out in roughly the same manner as in Japanese Patent No. 6187665. In this way, anisotropic conductive films of Examples 1 to 6 and Comparative Examples 1 to 2 were produced as filler-containing films. The number density of the conductive particles was 28,000 particles / mm 2 .

[0122] [Table 1]

[0123]

[0124] <Evaluation>

[0125] The anisotropic conductive films of the examples, comparative examples, and reference examples thus produced were tested and evaluated for filler immobility and conductivity as follows.

[0126] (Immobility)

[0127] In order to evaluate the immobility of the filler, the particle capture property was evaluated. Specifically, the anisotropic conductive film of each embodiment and comparative example was sandwiched between an IC for evaluating particle capture and a glass substrate (ITO wiring) corresponding to the terminal (bump) pattern with an alignment of 6 μm, and heated and pressed (180°C, 60 MPa, 5 seconds) to form a connection structure for evaluation. In this connection structure, the number of conductive particles captured was measured for 100 of the 6 μm × 66.6 μm area where the bump of the evaluation IC overlaps with the terminal of the glass substrate, and the minimum capture number was obtained. The evaluation was performed according to the following particle capture evaluation criteria. The results are shown in Table 2. In practical applications, an A or B evaluation is expected.

[0128] IC for evaluating particle capture performance

[0129] Dimensions: 1.6×29.8mm.

[0130] Thickness: 0.3mm.

[0131] Bump specifications: width 12μm × length 66.6μm, bump distance 22μm (L / S=12μm / 10μm), bump height 12μm.

[0132] Particle capture evaluation criteria

[0133] Grade Benchmark

[0134] A: The minimum number of captures is 5 or more.

[0135] B: The minimum number of captures is 3 or more and less than 5.

[0136] C: The minimum number of captures is 1 or more and less than 3.

[0137] D: The minimum number of captures is 0.

[0138] (Continuity)

[0139] The anisotropic conductive films of each Example, Comparative Example, and Reference Example were sandwiched between an IC for conductivity evaluation and a glass substrate. Heat and pressure were applied (170°C, 20 MPa, 10 seconds) to create a connection structure for evaluation. The initial on-resistance was measured and evaluated according to the following conductivity evaluation criteria. The results are shown in Table 2. For practical applications, an initial on-resistance rating of A or B is required.

[0140] Here, the terminal (bump) patterns of the evaluation IC and the glass substrate corresponded to each other and had the following dimensions: When connecting the evaluation IC and the glass substrate, the long dimension of the anisotropic conductive film and the short dimension of the bump were aligned.

[0141] IC for evaluating conductivity

[0142] Dimensions: 1.8×20.0mm.

[0143] Thickness: 0.5mm.

[0144] Bump specifications: width 30μm × length 85μm, bump distance 50μm, bump height 15μm.

[0145] Glass substrate (Ti / Al wiring)

[0146] Glass material: 1737F manufactured by Corning.

[0147] Dimensions: 30×50mm.

[0148] Thickness: 0.5mm.

[0149] Continuity evaluation criteria

[0150] Grade Benchmark

[0151] A: The initial on-resistance is less than 1.0Ω.

[0152] B: The initial on-resistance is 1.0Ω or more and less than 2.0Ω.

[0153] C: The initial on-resistance is 2.0Ω or more and less than 4.0Ω.

[0154] D: The initial on-resistance is 4.0Ω or more.

[0155] [Table 2]

[0156]

[0157] <Results Review>

[0158] The filler-containing films (anisotropic conductive films) of Examples 1 to 6 were rated A or B for both immobility and conductivity because the thickness of the bottom cap of the second recess in the intermediate layer was less than 0.5 times the average particle size of the filler. In contrast, the filler-containing film of Comparative Example 1 was rated C for conductivity because the recesses were through-holes. Furthermore, the filler-containing film of Comparative Example 2 was rated C for immobility because both the thickness of the bottom cap of the second recess and the thickness of the sidewall of the second recess exceeded 0.5 times the average particle size of the filler.

[0159] Possibility of industrial application

[0160] In the filler-containing film of the present invention, which has a structure in which an intermediate layer is sandwiched between a first insulating layer and a second insulating layer, a second recess is provided in the intermediate layer, which fits into the first recess of the first insulating layer, and the filler is filled and retained in the second recess. This allows the filler to be retained without providing a through-hole in the intermediate layer. Furthermore, the thickness of the bottom cover portion of the second recess in the intermediate layer is limited to a specific range. This avoids problems that arise when connecting two components through the filler-containing film by compression bonding, such as thermocompression bonding, and is therefore useful as a conductive film or anisotropic conductive film.

[0161] Description of reference numerals:

[0162] 1, 21: first insulating layer; 2, 22: intermediate layer; 3, 23: second insulating layer; 4, 24: first recess; 5, 25: second recess; 5a, 25a: side wall portion of the second recess; 5b, 25b: bottom cover portion of the second recess; 6, 26: filler; 10, 20: film containing filler; MB: metal plate; RF: peeling film; PM: stamper; a: layer thickness of the intermediate layer; b: opening diameter of the second recess; c: diameter of the bottom cover of the second recess; d: outer diameter of the bottom cover of the second recess; e: depth of the second recess; f: thickness of the bottom cover of the second recess; g: thickness of the side wall of the second recess; h: depth of the first recess.

Claims

1. A film containing a filler, wherein The filler-containing film is sequentially stacked with a first insulating layer, an intermediate layer, and a second insulating layer. The first insulating layer has a first recess on the intermediate layer side, The middle layer has a second recess, the second recess has a side wall portion and a bottom cover portion, and the second recess is embedded in the first recess of the first insulating layer. The filler is held in the second recess, The thickness of the bottom cover portion of the second recessed portion of the intermediate layer is 0.5 times or less the average particle size of the filler.

2. The filler-containing film according to claim 1, wherein The thickness of the intermediate layer is 0.6 times or more and 10 times or less the average particle size of the filler.

3. The filler-containing film according to claim 1 or 2, wherein The depth of the second recessed portion of the intermediate layer is not less than 0.2 times and not more than 2 times the average particle size of the filler.

4. The filler-containing film according to claim 1 or 2, wherein The opening diameter of the second recessed portion of the intermediate layer is 1.0 times or more and 3.0 times or less the average particle diameter of the filler.

5. The filler-containing film according to claim 1 or 2, wherein The average particle size of the filler is 1 μm or more and 200 μm or less.

6. The filler-containing film according to claim 1 or 2, wherein The first recesses are regularly arranged in the first insulating layer.

7. The filler-containing film according to claim 1 or 2, wherein The filler is conductive particles, and the film containing the filler is used as a conductive film or an anisotropic conductive film. 8 . A connected structure obtained by connecting a first member and a second member via the filler-containing film according to claim 1 .

9. A connection structure obtained by conductively connecting a first electronic component and a second electronic component to each other or anisotropically conductively connecting them through the filler-containing film according to claim 7 used as a conductive film or an anisotropic conductive film.

10. A method for manufacturing a connection structure, wherein: The first component and the second component are connected via the filler-containing film according to claim 1 .

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

12. A connection method, wherein: The first component and the second component are connected by the film containing filler according to claim 1, The filler-containing film is temporarily attached to the second member from the first insulating layer side of the film, and the first member is placed on the temporarily attached filler-containing film and pressure-bonded from the first member side.

13. A connection method, wherein: Conductive connection or anisotropic conductive connection of a first electronic component to a second electronic component via the filler-containing film according to claim 7 used as a conductive film or an anisotropic conductive film, The filler-containing film is temporarily attached to the second electronic component from the first insulating layer side of the film, and the first electronic component is mounted on the temporarily attached filler-containing film and pressure-bonded from the first electronic component side.

14. A precursor film, wherein Suitable for the production of a filler-containing film having a first insulating layer, an intermediate layer, and a second insulating layer laminated in sequence, The precursor film has a structure in which a first insulating layer and an intermediate layer are stacked. The first insulating layer has a first recess on the intermediate layer side, The middle layer has a second recess having a side wall portion and a bottom cover portion, and the second recess is embedded in the first recess of the first insulating layer.

15. The precursor film according to claim 14, wherein The thickness of the bottom cover portion of the second recessed portion of the intermediate layer is not less than 0.8 times and less than 2 times the opening diameter of the second recessed portion.

Images