Method for manufacturing connection structure, connection film, and method for manufacturing connection film

Abstract

Provided is a method for manufacturing a connection structure that makes it possible to mount electronic parts at a high density by using a connection film with insufficient printing (blur) in an adhesive layer.　The method for manufacturing a connection structure, in which first terminals 5 of a first electronic part 3 having the first terminals 5 and second terminals 6 of a second electronic part 4 having the second terminals 6 are connected via a cured film 11A obtained by curing an adhesive layer 11 of a connection film 2, involves: a pasting step for pasting the adhesive layer 11 of the connection film 2 to the first electronic part 3; a placement step for placing the second terminals 6 on the first terminals 5 with the adhesive layer 11 therebetween; and a connection step for pressing the second electronic part 4 and curing the adhesive layer 11. The adhesive layer 11 has a body 12 that has a prescribed thickness and tapered inclination parts that are formed on both end sides of the body 12 in the width direction. In the pasting step, the pasting is performed while aligning the body 12 with the first terminals 5 in the width direction of the adhesive layer 11.

Description

Method for manufacturing connection structure, connection film, and method for manufacturing connection film

[0001] This application claims priority from Japanese Patent Application No. 2024-052333, filed on March 27, 2024, which is incorporated herein by reference.

[0002] In recent years, not only smartphones but also mobile terminals and display devices have become increasingly densely packed with components. As a result, while mounted components are becoming smaller, restrictions are also arising due to the narrowing of mounting space. For example, in camera modules, cameras (imaging units, image sensors) are becoming larger and more multi-lensed, which requires more space for installation.

[0003] Fig. 26 is a perspective view showing an example of a camera module substrate, Fig. 26(A) is a perspective view showing an example of a substrate having a recess (cavity) on the mounting surface, and Fig. 26(B) is a perspective view showing an example of a substrate having a polygonal mounting surface. As shown in Fig. 26(A) and Fig. 26(B), in order to secure space, various measures have been taken to eliminate unnecessary portions, such as rounding off corners 101 of the substrate and FPC (Flexible Printed Circuits) and providing recesses 102 on the mounting surface.

[0004] Substrates with such complex shapes are difficult to handle with ordinary connection films. One mounting method for substrates with complex shapes is to apply conductive paste using a dispenser, but this makes it difficult to achieve positional accuracy, control over overflow, and achieve uniform thickness, resulting in unstable electrical connections. Furthermore, applying the paste using a dispenser is difficult because it takes too much time in the process, which affects yield.

[0005] Patent Document 1 discloses a method for cutting a support film in half, removing unnecessary connection film portions, and dividing the connection film into individual pieces. However, the technique described in Patent Document 1 increases material waste and the number of processes, and there is still room for improvement in the productivity of the connection film.

[0006] Furthermore, with the demand for greater space savings, it has become necessary to devise ways to process the film so that it can accommodate designs with thinner line widths. However, when slitting the film to narrow widths, the conductive adhesive layer can peel off from the support film, making it difficult to produce long lengths. With conventional processing methods, there are concerns that productivity will decrease when the film is made longer if it is made less than 0.5 mm wide.

[0007] Japanese Patent Application Laid-Open No. 2020-198422

[0008] One method under consideration is to print a thin conductive adhesive on a support film and then slit the support film. This manufacturing method has the drawback that the thickness of the thinly printed conductive adhesive gradually decreases in a tapered manner toward the widthwise edges due to insufficient printing (fading), making it difficult to achieve uniformity. Insufficient printing (fading) can also be described as insufficient resin at the edges.

[0009] Furthermore, electronic components generally have multiple terminals arranged in an array, and there are gaps in the array direction called inter-terminal spaces (between bumps). Therefore, when using a connecting film to connect electronic components, it is necessary to design the behavior of the resin filling.

[0010] Therefore, the present technology aims to provide a method for manufacturing a connection structure that allows electronic components to be mounted at high density using a connection film with insufficient printing (faintness) in the adhesive layer, and a connection film and manufacturing method therefor that can be processed even when conductive adhesive is printed in a narrow width.

[0011] In order to solve the above-mentioned problems, the method for manufacturing a connection structure according to the present technology is a method for manufacturing a connection structure in which a first terminal of a first electronic component having a first terminal and a second terminal of a second electronic component having a second terminal are connected by a cured film formed by curing an adhesive layer of a connection film, and the method includes an attachment step of attaching the adhesive layer of the connection film to the first electronic component, an arrangement step of arranging the second terminal on the first terminal via the adhesive layer, and a connection step of pressing the second electronic component and curing the adhesive layer, wherein the adhesive layer has a main body portion having a predetermined thickness and tapered inclined portions formed on both ends of the main body portion in the width direction, and in the attachment step, the main body portion is attached to the first terminal in the width direction of the adhesive layer.

[0012] In addition, the connection film according to the present technology has a release-treated film and an adhesive layer laminated along the longitudinal direction of the release-treated film, and the adhesive layer has a main body portion having a predetermined thickness and tapered inclined portions formed on both ends of the main body portion in the width direction, and the width of the inclined portions is 5% to 20% of the width of the adhesive layer.

[0013] In addition, the manufacturing method of the connection film according to the present technology includes an adhesive layer forming step of applying an adhesive in a predetermined shape onto a release-treated film and forming a plurality of adhesive layers in a stripe pattern on the release-treated film, and a slitting step of slitting the release-treated film to a predetermined width according to the adhesive layers, wherein the adhesive layer has a main body portion having a predetermined thickness and tapered inclined portions formed on both ends of the main body portion in the width direction, and is cut so that the width of the inclined portions is 5% to 20% of the width of the adhesive layer.

[0014] According to this technique, electronic components can be mounted at high density using a connection film with an inclined portion (faint portion) in the adhesive layer.

[0015] FIG. 1 is a diagram showing a manufacturing process of a connection structure 1 to which the present technology is applied, with (A) and (B) being cross-sectional views showing an attachment process, and (C) being a cross-sectional view showing an arrangement process. FIG. 2 is a cross-sectional view schematically showing the connection process. FIG. 3 is a cross-sectional view showing the connection structure 1. FIG. 4(A) is a cross-sectional view showing a state in which alignment of a first terminal provided independently of the connection film is performed in the attachment process, and FIG. 4(B) is a cross-sectional view showing a state in which an adhesive layer has been attached. FIG. 5 is a cross-sectional view showing a connection process in a manufacturing process of a connection structure shown for comparison. FIG. 6 is a cross-sectional view of a connection structure manufactured by the manufacturing process shown in FIG. 5. FIG. 7 is a cross-sectional view showing an example of a configuration of a connection film to which the present technology is applied. FIG. 8 is a cross-sectional view showing an example of a connection film in which an inclined portion is provided on only one side of the adhesive layer. FIG. 9 is a cross-sectional view showing an example of a connection film in which an end of an inclined portion has a cut surface cut in the thickness direction of the adhesive layer. 10 is a cross-sectional view showing an example of an adhesive layer formed by laminating a conductive adhesive layer and an insulating adhesive layer. (A) shows an example of a coating structure in which an upper conductive adhesive layer covers both side edges of a lower insulating adhesive layer. (B) shows an example of a coating structure in which an upper insulating adhesive layer covers both side edges of a lower conductive adhesive layer. (C) shows an example of a laminate structure in which an upper layer is a conductive adhesive layer and a lower layer is an insulating adhesive layer. (D) shows an example of a laminate structure in which an upper layer is a conductive adhesive layer and a lower layer is an insulating adhesive layer. FIG. 11 is a diagram showing a manufacturing process of a connection film. (A) is a perspective view showing an adhesive application process. (B) is a perspective view showing a state in which multiple adhesive layers are formed in a stripe pattern on a release-treated film. (C) is a perspective view showing a process in which the release-treated film is slit to a predetermined width according to the adhesive layer. FIG. 12 is a side view showing an example of a process in which an adhesive is applied to a release-treated film 10. FIG. 13 is a perspective view showing a film roll. Fig. 14 is a cross-sectional view showing another example of a laminated structure of a conductive adhesive layer and an insulating adhesive layer. Fig. 15 is a plan view for explaining a manufacturing example of the connection film shown in Fig. 14. Fig. 16 is a diagram showing an example of a manufacturing method of the connection film. Fig. 17 is a cross-sectional view showing a modified example of the adhesive layer.Fig. 18 is a cross-sectional view showing an adhesive layer in which a conductive adhesive layer is laminated biased to the left side in the width direction of the insulating adhesive layer, thereby providing a single-layer region of the insulating adhesive layer on the right end side of the conductive adhesive layer without the conductive adhesive layer, and the left end of the conductive adhesive layer is approximately flush with the release-treated film and the left end of the insulating adhesive layer. Fig. 19 is a cross-sectional view showing an adhesive layer in which a conductive adhesive layer is laminated biased to the left side in the width direction of the conductive adhesive layer, thereby providing a single-layer region of the conductive adhesive layer on the right end side of the insulating adhesive layer without the insulating adhesive layer, and the left end of the insulating adhesive layer is approximately flush with the release-treated film and the left end of the conductive adhesive layer. Fig. 20 is a cross-sectional view showing an adhesive layer in which both width-wise ends of the insulating adhesive layer formed on a release-treated film have been removed. Fig. 21 is a cross-sectional view showing an adhesive layer in which both width-wise ends of the conductive adhesive layer formed on a release-treated film have been removed. 22 shows a connection film A having a small inclined portion width, where (A) is a cross-sectional view showing the adhesive layer after preparation, and (B) is a cross-sectional view and plan view showing the connection film having a cut surface cut in the thickness direction by a slit on one side and an inclined portion on the other side, showing the dimensional relationship. 23 shows a connection film B having a large inclined portion width, where (A) is a cross-sectional view showing the adhesive layer after preparation, and (B) is a cross-sectional view and plan view showing the connection film having a cut surface cut in the thickness direction by a slit on one side and an inclined portion on the other side, showing the dimensional relationship. 24 is a perspective view showing the process of attaching a film-like adhesive layer to a terminal row formed by arranging a plurality of terminals along the side edge near the side edge of an evaluation substrate. Fig. 25(A) is a cross-sectional view showing the bonding process according to Example 1, Fig. 25(B) is a cross-sectional view showing the bonding process according to Example 2, Fig. 25(C) is a cross-sectional view showing the bonding process according to Example 3, Fig. 25(D) is a cross-sectional view showing the bonding process according to Comparative Example 1, and Fig. 25(E) is a cross-sectional view showing the bonding process according to Comparative Example 2. Fig. 26 is a perspective view schematically showing an example of a conventional substrate, (A) is a perspective view schematically showing an example of a substrate having a recess (cavity) on its mounting surface, and (B) is a perspective view schematically showing an example of a substrate whose mounting surface is polygonal.

[0016] Hereinafter, a connection structure manufacturing method, a connection film, and a connection film manufacturing method to which the present technology is applied will be described in detail with reference to the drawings. Note that the present technology is not limited to the following embodiments, and various modifications are possible within the scope of the present technology. Furthermore, the drawings are schematic, and the ratios of the dimensions may differ from the actual ones. Specific dimensions should be determined with reference to the following explanation. Furthermore, the drawings may include parts in which the dimensional relationships and ratios differ from one another.

[0017] [Method for manufacturing connection structure] A method for manufacturing a connection structure to which the present technology is applied is a method for manufacturing a connection structure in which a first terminal of a first electronic component having a first terminal and a second terminal of a second electronic component having a second terminal are connected by a cured film formed by curing an adhesive layer of a connection film, and includes an attachment step of attaching the adhesive layer of the connection film to the first electronic component, an arrangement step of arranging the second terminal on the first terminal via the adhesive layer, and a connection step of pressing the second electronic component and curing the adhesive layer.

[0018] The adhesive layer has tapered inclined portions formed at both widthwise ends, and in the attaching step, the center portion in the widthwise direction is aligned with the center position of the first terminal.

[0019] 1 and 2 are diagrams showing the manufacturing process of a connection structure 1 to which the present technology is applied, in which Fig. 1(A) and Fig. 1(B) show the attachment process, Fig. 1(C) shows the arrangement process, and Fig. 2 schematically shows the connection process. Fig. 3 is a cross-sectional view showing the connection structure 1.

[0020] [First Electronic Component / Second Electronic Component] There are no particular limitations on the first electronic component 3 and the second electronic component 4, and they can be appropriately selected depending on the purpose. Examples of the first electronic component 3 and the second electronic component 4 include ceramic substrates, rigid substrates, flexible substrates (FPC: Flexible Printed Circuits), glass substrates, plastic substrates, resin multilayer substrates, IC (Integrated Circuit) modules, IC chips, connectors, LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), switches, etc.

[0021] The first electronic component 3 has first terminals 5 formed thereon. The first terminals 5 may be formed individually and independently, or a plurality of terminals may form a terminal row 5R. The locations of the first terminals 5 are not particularly limited and may be appropriately designed depending on the wiring pattern of the first electronic component 3. However, the present technology is particularly effective when the first terminals 5 are formed at the edge of the substrate of the first electronic component 3. The second terminals 6 formed on the second electronic component 4 and connected to the first terminals 5 may also be formed individually and independently, or a plurality of terminals may form a terminal row 6R. The locations of the second terminals 6 are not particularly limited and may be appropriately designed depending on the wiring pattern of the second electronic component 4. However, the present technology is particularly effective when the second terminals 6 are formed at the edge of the substrate of the second electronic component 4.

[0022] The connection structure according to the present technology is not particularly limited, and can be used in manufacturing methods for any electronic device that uses electrical connections, such as semiconductor devices (including driver ICs as well as optical elements, thermoelectric conversion elements, photoelectric conversion elements, and other devices that use semiconductors), display devices (monitors, televisions, head-mounted displays, etc.), mobile devices (tablet terminals, smartphones, wearable terminals, etc.), game consoles, audio equipment, imaging devices (those that use image sensors such as camera modules), electrical mounting for vehicles (mobile devices), medical equipment, sensor devices (touch sensors, fingerprint authentication, iris authentication, etc.), and home appliances.

[0023] [Connecting Film] The connecting film 2 has a release-treated film 10 and an adhesive layer 11 laminated on the release-treated film 10. The adhesive layer 11 has a main body portion 12 having a predetermined thickness and tapered inclined portions 13 formed on both ends of the main body portion 12 in the width direction.

[0024] The connecting film 2 is not particularly limited, and examples thereof include a film-shaped (which can also be described as a membrane-shaped, ridge-shaped, or convex, hereinafter referred to simply as "film-shaped") conductive film containing conductive particles, an anisotropic conductive film (ACF), and a film-shaped adhesive film (NCF: Non-Conductive Film). These may be multi-layered, consisting of two or more layers. The curing type of the connecting film 2 is not particularly limited, and examples thereof include a thermosetting type, a photosetting type, and a photothermal and combined photosetting type. The connecting film 2 may also be a hot-melt type using a thermoplastic resin.

[0025] The specific configuration of the connecting film 2 and the manufacturing process of the connecting film 2 will be described in detail later.

[0026] [Attachment Step] In the attachment step, the adhesive layer 11 of the connection film 2 is transferred to the first electronic component 3. As described above, the first electronic component 3 and the second electronic component 4 are not particularly limited and can be selected appropriately depending on the purpose. In this specification, the electronic component to which the connection film 2 is attached in the attachment step is referred to as the first electronic component 3.

[0027] The adhesive layer 11 is transferred by, for example, using a bonding device to press the connection film 2 from the release-treated film 10 side, and bonding the adhesive layer 11 to the mounting surface of the first electronic component 3 on the stage. The connection film 2 with the transferred adhesive layer 11 is then rolled up, leaving only the release-treated film 10. A plurality of adhesive layers may be provided on a relatively large release-treated film 10. They can be used in the same manner, except that the required portion is cut off when in use.

[0028] When the first terminals 5 are formed individually and independently, the adhesive layer 11 cut into individual pieces is attached to the first terminals 5. When a plurality of first terminals 5 form a terminal row 5R, the adhesive layer 11 formed in a film shape is attached to the terminal row 5R.

[0029] 4A is a cross-sectional view showing the state in which the connection film 2 and the first terminal 5 are aligned in the attachment process, and FIG. 4B is a cross-sectional view showing the state in which the adhesive layer 11 has been attached. As shown in FIG. 4A , in the attachment process, the body portion 12 is attached so that the width direction 11W of the adhesive layer 11 is aligned with the longitudinal direction 5L of the first terminal 5. The adhesive layer 11 is preferably aligned so that the center position of the width direction 11W of the body portion 12 is the center position of the longitudinal direction 5L of the first terminal 5. This prevents the inclined portion 13 from being positioned on the center of the first terminal 5, improving the reliability of conduction and connection.

[0030] 4, the inclined portion 13 is preferably formed at a distance that does not extend beyond the substrate side edge 16 of the first electronic component 3. This prevents the adhesive layer 11 from getting around and contaminating the surface or back of the stage on which the first electronic component 3 is placed, during the step of connecting the second electronic component 4.

[0031] 1A is a cross-sectional view showing a state in which a connection film 2 having a film-like adhesive layer 11 provided on a plurality of first terminal portions 5 is aligned, and FIG. 1B is a cross-sectional view showing a state in which the adhesive layer 11 has been temporarily attached to a first electronic component 3. As shown in FIG. 1A , in the attachment step, the connection film 2 is attached to the first electronic component 3 by aligning the main body portion 12 with the terminal row 5R of the first terminals 5 in the longitudinal direction 11L of the adhesive layer 11. The adhesive layer 11 is preferably aligned so that the center position of the main body portion 12 in the longitudinal direction 11L is the center position of the terminal row 5R in the arrangement direction 5RL of the first terminals 5.

[0032] In the bonding step, the connection film 2 may be bonded to the plurality of terminal rows 5R in a plurality of batches, or the connection film 2 may be bonded all at once.

[0033] [Placement Process] The placement process is a process of mounting the second electronic component 4 on the first electronic component 3 via the connection film 2. As shown in Fig. 1C , in the placement process, the first terminals 5 or first terminal rows 5R of the first electronic component 3 to which the adhesive layer 11 has been transferred are aligned with the second terminals 6 or second terminal rows 6R of the second electronic component 4.

[0034] [Connection Process] The connection process is a process of electrically and mechanically connecting the first electronic component 3 and the second electronic component 4 by pressing the second electronic component 4 and curing the connection film 2. As shown in Fig. 2 , in the connection process, for example, a crimping tool 18 is used to press the first terminals 5 or the first terminal row 5R of the first electronic component 3 and the second terminals 6 or the second terminal row 6R of the second electronic component 4 via a buffer material 17, and heating, light irradiation, or the like is performed depending on the curing type of the connection film 2 to cure the adhesive layer 11.

[0035] Here, the adhesive layer 11 has tapered inclined portions 13 formed on both ends of the main body portion 12 in the width direction 11W. Therefore, as shown in FIG. 2, the amount of resin flowing to both ends of the terminal row 6R of the second terminals 6 and between the terminals due to pressure application during the connection process is reduced. This makes it possible to control excessive resin flow and, if conductive particles are contained, makes it easier to control particle capture. Furthermore, even if conductive particles are aligned in the adhesive layer 11, it is possible to suppress alignment disturbances due to the influence of resin flow. Note that FIG. 2 is a schematic diagram for more clearly illustrating the inclined portions 13 of the adhesive layer 11.

[0036] [Connection Structure] Fig. 3 is a cross-sectional view showing a connection structure 1. As shown in Fig. 3, the connection structure 1 is formed by connecting a first terminal 5 of a first electronic component 3 and a second terminal 6 of a second electronic component 4 via a cured film 11A formed by curing an adhesive layer 11. In the case of a hot-melt type connection film 2, the cured film 11A is melt-bonded and connected by the hot-melt type connection film 2. For convenience, the cured film 11A may be considered to include the hot-melt type. The first terminal 5 and the second terminal 6 are electrically connected via conductive particles contained in the adhesive layer 11 or by being directly connected.

[0037] As described above, in the connection process, the amount of resin flowing to both ends of the terminal row 6R of the second terminals 6 is controlled, and therefore the formation of the fillet 8 around the second electronic component 4 can also be controlled. That is, the fillet 8 can be formed with an amount of resin sufficient to ensure the strength required for connecting the second electronic component 4, eliminating unnecessary resin and suppressing the spread of the fillet 8, making it easier to accommodate higher density mounting areas and allowing for the mounting of multiple miniaturized electronic components. Furthermore, because the connection structure 1 is less affected by resin flow in the connection process, there is no risk of a decrease in the capture rate of conductive particles or disturbances in the arrangement, and it has good connectivity.

[0038] FIG. 5 is a cross-sectional view showing a connection step in a manufacturing process for a connection structure shown for comparison, and FIG. 6 is a cross-sectional view of a connection structure manufactured by the manufacturing process shown in FIG. 5. As shown in FIG. 5, if tapered slopes are not formed on both ends of the main body of the adhesive layer, the insulating binder flows evenly, as indicated by the arrows in the figure. This results in a large amount of resin flowing to both ends of the second terminal row 6R and spreading across the mounting area. This can lead to a decrease in the capture rate of conductive particles and disruption of the arrangement. Furthermore, as shown in FIG. 6, unnecessary resin causes the fillet 8 to expand, making it difficult to accommodate a high-density mounting area. Furthermore, the flowing resin can also cause contamination of surrounding components and the stage on which the first electronic component 3 is placed.

[0039] [Connection Film] Next, the configuration of the connection film 2 will be described. As described above, the connection film 2 has a release-treated film 10 and an adhesive layer 11 laminated along the longitudinal direction of the release-treated film 10. The adhesive layer 11 has a main body portion 12 with a predetermined thickness and tapered inclined portions 13 formed on both ends of the main body portion 12 in the width direction. Note that the connection film 2 is formed by providing the adhesive layer 11 of a predetermined shape along the longitudinal direction of the release-treated film 10, and the shape can also be described as film-like, bulging, or convex. In this specification, the term "film-like" is used to encompass these meanings.

[0040] [Release-treated film] As described below, the release-treated film 10 is a substrate that has been subjected to a release treatment, for example, with a silicone resin. Examples of the release-treated film 10 include PET (Poly Ethylene Terephthalate), OPP (Oriented Polypropylene), PMP (Poly-4-methylpentene-1), and PTFE (Polytetrafluoroethylene). In addition, at least the surface of the release-treated film 10 facing the adhesive layer 11 has been subjected to a release treatment, for example, with a silicone resin.

[0041] The thickness of the release-treated film 10 is not particularly limited. The lower limit of the thickness is preferably 10 μm or more in terms of separation, more preferably 25 μm or more, and even more preferably 38 μm or more. The upper limit of the thickness is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 75 μm or less, because if the thickness is too thick, there is a concern that excessive pressure will be applied to the connection film. It may also be 50 μm or less.

[0042] Furthermore, the width of the release-treated film 10 is not particularly limited. The lower limit of the width may be 0.5 mm or more, and is preferably 1 mm or more in terms of rewinding, more preferably 2 mm or more, and even more preferably 4 mm or more. The upper limit of the width is preferably 500 mm or less, more preferably 250 mm or less, and even more preferably 120 mm or less, because if it is too large, it may be difficult to carry or handle. In practice, it may be 50 mm or less in order to reduce capital investment such as modifying the device for attaching the reel. When multiple reels are provided on the release-treated film 10, a relatively large area is required, so the upper limit may be as wide as this.

[0043] [Adhesive Layer] The adhesive constituting the adhesive layer 11 can be appropriately selected depending on the purpose from insulating binders such as heat-curing, photo-curing, photo-thermal curing, and hot-melt types. The adhesive layer 11 may also be a conductive adhesive layer containing a filler such as conductive particles in an insulating binder. The conductive particles may be dispersed or arranged in a resin. When the conductive particles are dispersed in a resin, they may be spaced apart and not in contact with each other.

[0044] The lower limit of the thickness of the adhesive layer 11 may be, for example, the same as the diameter of the conductive particles, and is preferably 1.3 times or more the diameter of the conductive particles, or 2 μm or more, and preferably 10 μm or more. The upper limit of the thickness of the adhesive layer 11 may be, for example, 200 μm or less, preferably 100 μm or less, and more preferably 40 μm or less, or 2 times or less the diameter of the conductive particles. When the adhesive layer 11 is made up of multiple layers, such as a laminate structure of a conductive adhesive layer and an insulating adhesive layer, the upper limit of the thickness is the total thickness of the layers.

[0045] The adhesive layer 11 may also be formed by laminating an insulating adhesive layer or pressure-sensitive adhesive layer that does not contain conductive particles, and the number of layers and lamination surface can be selected appropriately depending on the target and purpose. The insulating resin for the insulating adhesive layer or pressure-sensitive adhesive layer can be the same as that for the conductive adhesive layer. The pressure-sensitive adhesive layer refers to one that does not contain a polymerizable resin that reacts during the connection process.

[0046] The width of the adhesive layer 11 is formed to be narrow, less than 0.5 mm. This makes it possible to provide an adhesive film that is compatible with miniaturization of mounted components, narrower mounting areas, and higher density. The lower limit of the width of the adhesive layer 11 is preferably 0.1 mm or more, more preferably 0.3 mm or more. The upper limit may be 0.95 times or less, preferably 0.9 times or less, and more preferably 0.8 times or less, that of the release-treated film. When the length of the adhesive layer 11 is in the width direction of the release-treated film 10, the upper limit may be 0.95 times or less, preferably 0.9 times or less, and more preferably 0.8 times or less, that of the release-treated film 10.

[0047] The conductive particles may be appropriately selected from those used in known anisotropic conductive films. Examples include metal particles such as nickel, copper, silver, gold, and palladium, alloy particles such as solder, and metal-coated resin particles in which the surface of resin particles such as polyamide and polybenzoguanamine is coated with a metal such as nickel. The surface may be insulated to the extent that it does not impair the conductive performance. Furthermore, the surface may have protrusions.

[0048] The particle diameter of the conductive particles is not particularly limited, but the lower limit of the particle diameter may be 1 μm or more, preferably 2 μm or more, and the upper limit of the particle diameter is, for example, preferably 50 μm or less, more preferably 20 μm or less, from the viewpoint of the capture efficiency of the conductive particles in the connection structure. The particle diameter of the conductive particles can be a value measured using an imaging particle size distribution analyzer (for example, FPIA-3000: manufactured by Malvern Instruments). The number of particles is preferably 1,000 or more, and preferably 2,000 or more.

[0049] The density of the conductive particles is adjusted appropriately within a range that does not affect the size of the electrode to be connected or the slits in the film, and is, for example, 30 to 500,000 particles / mm in the surface field of view. ２ This allows for excellent conductivity and insulation even when the size of the electrode to be connected is small. The number density of the conductive particles is that of the arranged portion of the conductive particles when the film is formed during production. This number density is measured by observing the conductive particles in the adhesive layer in a plan view using an optical microscope or a metallurgical microscope, and measuring the number of conductive particles in 10 or more areas within a total of 2 mm ２ It is preferable to measure so that the total number of conductive particles is 200 or more. When determining the particle number density from a plurality of pieces, the particle surface density can be determined from the area obtained by excluding the spaces between the pieces from the area including the pieces and the spaces, and the number of particles.

[0050] Known insulating binders can be used as the insulating binder (insulating resin). Examples of curing types include thermosetting, photocuring, and photothermal combined curing. Examples include photoradical polymerization resin compositions containing a (meth)acrylate compound and a photoradical polymerization initiator, thermal radical polymerization resin compositions containing a (meth)acrylate compound and a thermal radical polymerization initiator, thermal cationic polymerization resin compositions containing an epoxy compound and a thermal cationic polymerization initiator, and thermal anionic polymerization resin compositions containing an epoxy compound and a thermal anionic polymerization initiator. Known pressure-sensitive adhesive compositions may also be used. For hot-melt types, the composition disclosed in JP 2014-060025 A can be used. Curing types are preferred for controlling the fluidity of the resin, while hot-melt types are preferred from the standpoint of film storage. The type may be selected according to the purpose.

[0051] Hereinafter, a specific example will be described, taking as an example a thermal radical polymerization insulating binder containing a film-forming resin, an elastomer, a (meth)acrylic monomer, a polymerization initiator, and a silane coupling agent. Note that the term "(meth)acrylic monomer" means both an acrylic monomer and a methacrylic monomer.

[0052] The film-forming resin is not particularly limited, and examples thereof include phenoxy resin, unsaturated polyester resin, saturated polyester resin, urethane resin, butadiene resin, polyimide resin, polyamide resin, and polyolefin resin. The film-forming resin may be used alone or in combination of two or more. Among these, phenoxy resin is particularly preferred from the viewpoints of film-forming ability, processability, and connection reliability. The phenoxy resin is a resin synthesized from bisphenol A and epichlorohydrin, and an appropriately synthesized product or a commercially available product may be used. The content of the film-forming resin is not particularly limited, and is preferably, for example, 10% to 60% by mass.

[0053] The elastomer is not particularly limited, and examples thereof include polyurethane resin (polyurethane elastomer), acrylic rubber, silicone rubber, and butadiene rubber.

[0054] The (meth)acrylic monomer is not particularly limited and may be, for example, a monofunctional (meth)acrylic monomer or a polyfunctional (meth)acrylic monomer having two or more functionalities. From the viewpoint of stress relaxation of the polymer, it is preferable that 80 mass % or more of the (meth)acrylic monomers in the insulating binder are monofunctional (meth)acrylic monomers.

[0055] From the viewpoint of adhesiveness, the monofunctional (meth)acrylic monomer preferably has a carboxylic acid. The molecular weight of the monofunctional (meth)acrylic monomer having a carboxylic acid is preferably 100 to 500, and more preferably 200 to 350. The content of the monofunctional (meth)acrylic monomer having a carboxylic acid in the insulating binder is preferably 3% by mass to 20% by mass, and more preferably 5% by mass to 10% by mass.

[0056] The polymerization initiator is not particularly limited as long as it can cure the (meth)acrylic monomer at a predetermined temperature during thermocompression bonding, and examples thereof include organic peroxides. Examples of organic peroxides include lauroyl peroxide, butyl peroxide, benzyl peroxide, dilauroyl peroxide, dibutyl peroxide, peroxydicarbonate, and benzoyl peroxide. These may be used alone or in combination of two or more. The content of the polymerization initiator in the insulating binder is not particularly limited, and is preferably, for example, 0.5% by mass to 15% by mass.

[0057] The silane coupling agent is not particularly limited, and examples thereof include epoxy-based silane coupling agents, acrylic-based silane coupling agents, thiol-based silane coupling agents, amine-based silane coupling agents, etc. The content of the silane coupling agent in the insulating binder is not particularly limited, and is preferably, for example, 0.1% by mass to 5.0% by mass.

[0058] The insulating binder may contain, as needed, fillers, softeners, accelerators, antioxidants, colorants (pigments, dyes), organic solvents, ion catchers, etc., in addition to the above-mentioned compounds. Colorants (pigments, dyes) may be added to improve the visibility of the film. Furthermore, known insulating fillers (so-called nanofillers) may be added to adjust the melt viscosity, etc.

[0059] 7, the adhesive layer 11 has a main body 12 having a predetermined thickness, and tapered inclined portions 13 formed on both widthwise ends of the main body 12. As will be described later, the inclined portions 13 are formed by the adhesive (insulating binder) being printed in a narrow width, and the thickness gradually decreasing in a tapered manner as it approaches the widthwise ends due to insufficient printing (fading).

[0060] The inclined portions 13 refer to regions on both widthwise ends of the main body 12 that have a thickness of 90% or less of the thickness of the main body 12. When the adhesive layer 11 is a conductive adhesive layer, the inclined portions 13 are areas where the coating thickness is thinner than the size (diameter) of the conductive particles.

[0061] In the adhesive layer 11, the width 13W of the inclined portion 13 is preferably 5% to 20% of the width 11W of the adhesive layer 11. If the width 13W of the inclined portion 13 of the width 11W of the adhesive layer 11 is less than 5%, the insulating binder of the connection structure 1 will protrude significantly, and if the ratio is greater than 20%, the width 11W of the adhesive layer 11 will be narrow, and the effective width during mounting will be narrow.

[0062] Furthermore, in the connection film 2, the width 11W of the adhesive layer 11 relative to the width 10W1 of the release-treated film 10 is preferably 50% to 95%. If the width 11W of the adhesive layer 11 relative to the width 10W1 of the release-treated film 10 is less than 50%, the area of ​​the adhesive layer 11 applied to the release-treated film 10 is reduced, resulting in waste of the release-treated film 10. If the ratio is greater than 95%, in the case of a narrow width, the blade may reach the adhesive portion due to meandering during slitting, and there is a risk that the adhesive layer 11 may lift off from the release-treated film 10.

[0063] Furthermore, the aspect ratio of the adhesive layer 11 between the thickness 12H of the main body portion 12 and the width 13W of the inclined portion 13 is preferably 100% or more and 400% or less. If the thickness 12H of the main body portion 12 exceeds 400% of the width of the inclined portion 13, fillets are likely to form, but it becomes difficult to keep the fillets at an appropriate size, which may result in contamination of other components. For this reason, the width 13W of the inclined portion 13 relative to the thickness 12H of the main body portion 12 is preferably 400% or less. Furthermore, if the thickness 12H of the main body portion 12 is less than 100% of the width 13W of the inclined portion 13, fillets are less likely to form and the adhesive strength is likely to decrease. For this reason, the width 13W of the inclined portion 13 relative to the thickness 12H of the main body portion 12 is preferably 100% or more.

[0064] The adhesive layer 11 may have inclined portions 13 on both sides of the main body 12 in the width direction, or may have inclined portions 13 on only one side and a cut surface 14 cut in the thickness direction of the adhesive layer 11 on the other side, as shown in Fig. 8. Furthermore, as shown in Fig. 9, the end of the inclined portion 13 may have a cut surface 14 cut in the thickness direction of the adhesive layer 11. The cut surface 14 can be formed, for example, by half-cutting the adhesive layer 11 in the thickness direction up to the release-treated film 10.

[0065] [Laminated structure] Figure 10 is a cross-sectional view showing examples of adhesive layers 11 formed by laminating a conductive adhesive layer 19 and an insulating adhesive layer 20, (A) shows an example of a coating structure in which the upper conductive adhesive layer 19 covers both side edges of the lower insulating adhesive layer 20, (B) shows an example of a coating structure in which the upper insulating adhesive layer 20 covers both side edges of the lower conductive adhesive layer 19, (C) shows an example of a laminated structure in which the upper layer is the conductive adhesive layer 19 and the lower layer is the insulating adhesive layer 20, and (D) shows an example of a laminated structure in which the upper layer is the insulating adhesive layer 20 and the lower layer is the conductive adhesive layer 19.

[0066] 10(A) and 10(C), in which a conductive adhesive layer 19 is provided on the upper layer, a motherboard substrate such as a ceramic substrate, a rigid substrate, or a glass substrate is preferably used as the first electronic component 3 to which the adhesive layer 11 is attached. In the configurations shown in Fig. 10(B) and 10(D), in which an insulating adhesive layer 20 is provided on the upper layer, a member that is pressed by a crimping tool 18, such as a flexible substrate, an IC module, or an IC chip, is preferably used as the first electronic component 3 to which the adhesive layer 11 is attached.

[0067] By configuring the adhesive layer 11 as a laminate of the conductive adhesive layer 19 and the insulating adhesive layer 20 shown in Figure 10, it becomes possible to adjust and control the fillet more effectively. That is, even if two or more layers are laminated, by adjusting the solid content, insulating microfiller content, melt viscosity, etc. of the layer on the release-treated film 10 side and the layer above it, it becomes possible to adjust the spreading and ease of pressing of the resin during connection. The solid content concentration of the coating liquid during production of the connecting film in the present invention, and the viscosity and melt viscosity of the connecting film after coating and formation can be designed appropriately according to the purpose.

[0068] [Method for Manufacturing Connecting Film] Next, the manufacturing process of the connecting film 2 will be described. The manufacturing process of the connecting film 2 includes an adhesive layer forming process of applying an adhesive 21 in a predetermined shape on a release-treated film 10 and forming a plurality of adhesive layers 11 in a stripe pattern on the release-treated film 10, and a slitting process of slitting the release-treated film 10 to a predetermined width according to the adhesive layers 11. Figure 11 is a diagram showing the manufacturing process of the connecting film 2, where (A) is a perspective view showing the application process of the adhesive 21, (B) is a perspective view showing the state in which a plurality of adhesive layers 11 have been formed in a stripe pattern on the release-treated film 10, and (C) is a perspective view showing the process of slitting the release-treated film 10 to a predetermined width according to the adhesive layers 11.

[0069] [Adhesive Layer Formation Process] The method for applying the adhesive 21 onto the release-treated film 10 is not particularly limited, and known methods can be used, such as screen printing using a plate (screen mask), inkjet printing in which the adhesive is spray-applied, and application using a dispenser. Among these, screen printing is suitable for adhesives with insulating binders (ADH: Adhesive), and is also suitable for paste-like adhesives with or without solvents, allowing for a high degree of freedom in adhesive component design and selection. Inkjet printing allows for direct patterning from data without the need for a plate. The printing method can be selected taking into consideration the properties of the release-treated film 10 and the adhesive 21, takt time, and the like. Screen printing will be described below as an example.

[0070] Fig. 11(A) is a perspective view schematically showing an example of a printing step in the manufacturing method of the connecting film 2. Fig. 12 is a side view showing an example of a step of applying an adhesive to a release-treated film 10. As shown in Fig. 12, in the printing step, adhesive 21 is passed through the meshes of a screen mask 23 by pressure from a squeegee 22 or the like, and printed (applied) on the release-treated film 10, thereby forming a plurality of adhesive layers 11 in a stripe pattern, as shown in Fig. 11(B).

[0071] The line width of each adhesive layer 11 formed in a stripe shape can be 1.0 mm or less, and can also be formed to a narrow width of less than 0.5 mm. The lower limit of the line width of each adhesive layer 11 can be, for example, 0.1 mm or more. With conventional methods such as half-cutting, due to the structure of the slits and half-cutting blades, it was difficult to manufacture a connection film having an adhesive layer with a width of less than 0.5 mm while taking into account productivity and long lengths. However, by combining printing and slitting, adhesive layers 11 with a width of less than 0.5 mm can be easily manufactured. This is particularly useful when manufacturing long lengths.

[0072] Tapered inclined portions 13 (faint portions) are formed on both widthwise ends of the adhesive layer 11. When the adhesive layer 11 is a conductive adhesive layer, the inclined portions 13 are portions where the coating thickness is thinner than the size (diameter) of the conductive particles.

[0073] Furthermore, the width 13W of the inclined portion 13 (faintness) can be adjusted by changing the plate making (screen mask) used during printing or the printing pressure conditions during printing. That is, by changing the plate making used during printing, the width 13W of the inclined portion 13 relative to the width 11W of the adhesive layer 11 can be adjusted. This allows the width 13W of the inclined portion 13 to be adjusted depending on the position on the substrate of the first terminal 5 where the adhesive layer 11 is provided so that the insulating binder does not stain the surrounding area during the connection step in which the second electronic component is pressed.

[0074] Furthermore, by changing the plate making during printing, it is possible to adjust the aspect ratio between the thickness 12H of the main body 12 of the adhesive layer 11 and the width 13W of the inclined portion 13. This aspect ratio can also be adjusted by the conditions of the coating liquid (composition, viscosity, solids concentration, solvent, etc.) and the printing conditions (printing pressure, drying, etc.), which allows for more advanced designs.

[0075] Each stripe-shaped adhesive layer 11 may be formed as a continuous solid line of adhesive 21, or as a continuous dashed or dotted line of individual pieces of adhesive 21 having a predetermined length spaced apart at a certain distance. That is, the area where the adhesive layer used for connection is formed may be formed as a discontinuous, scattered pattern. In this case, the dotted line preferably has a size large enough to contribute to the performance of the connection structure. It may be considered as a simple "dot," or in this case, the collection of dots (i.e., the "dotted line" used for connection) may be considered to have an area that contributes to the connection. Furthermore, individual pieces of different shapes may be mixed in one stripe of adhesive layer 11. The individual pieces may be half-cut on the release-treated film 10 (preferably after the drying process described below).

[0076] The screen mask 23 is a plate using a screen mesh woven from synthetic fibers such as polyester or stainless steel or various metal fibers. When the adhesive 21 contains conductive particles, the mesh should be larger than the maximum diameter of the conductive particles.

[0077] A drying step may be performed after the application of the adhesive 21. In the drying step, the adhesive 21 applied in a predetermined shape is dried to form an adhesive layer 11 of a predetermined shape on the release-treated film 10. An oven or a dryer is preferably used for drying. In the adhesive layer formation step, a plurality of adhesive layers 11 of a predetermined shape may be arranged in a certain direction on the release-treated film 10, and the adhesive layers 11 may be arranged in a stripe pattern. This allows for efficient production of individual adhesive layers 11 corresponding to substrates or mounting areas with complex shapes. Furthermore, compared to providing a film on a roll and processing it to create individual pieces, this method can reduce the amount of film raw material and solvent used, thereby contributing to a reduction in environmental impact.

[0078] The conductive particles may be arranged after the application of the adhesive 21. The conductive particles may be arranged randomly or regularly. Examples of the arrangement method include a transfer method. Examples of the transfer method include a method in which the conductive particles are attached to a weakly adhesive layer of a transfer body, and the conductive particle-attached surface of the transfer body is overlapped with and pressed against the adhesive 21 applied in a predetermined shape, thereby transferring the conductive particles to the adhesive layer 11 of a predetermined shape. The transfer method is not limited to this. Furthermore, arrangement methods other than transfer are not excluded. The adhesive layer 11 may be formed in multiple columns and rows on a base film, and the release-treated film 10 may be cut to create individual pieces. These may also be transferred onto a single long release-treated film 10.

[0079] [Slitting Process] Next, as shown in Fig. 11(C), the release-treated film 10 on which a plurality of adhesive layers 11 are formed in a stripe pattern is cut along the stripes of the adhesive layers 11. This allows a connection film 2 on which narrow adhesive layers 11 are formed. If necessary, a plurality of connection films 2 may be joined in the longitudinal direction to form a long film. Alternatively, as shown in Fig. 13, a long connection film 2 may be wound around a winding core 30 to form a film winding body 31.

[0080] In the slitting process, the release-treated film 10 is cut only between the stripes of the adhesive layer 11, thereby forming a connection film 2 in which the adhesive layer 11 is disposed inside the release-treated film 10. Therefore, by adjusting the application width of the adhesive layer 11 and the spacing between the stripes in the adhesive layer forming process, it is possible to adjust the width 11W of the adhesive layer 11 relative to the width 10W1 of the release-treated film 10. Furthermore, by adjusting the plate-making of the adhesive 21 and the spacing between the stripes in the adhesive layer forming process, it is possible to adjust the width 13W of the inclined portion 13 relative to the side edge width 10W2 from the side edge of the release-treated film 10 to the adhesive layer 11.

[0081] In the slitting step, the release-treated film 10 and the adhesive layer 11 may be slit together so that the side of the adhesive layer 11 coincides with the side of the release-treated film 1. Alternatively, the adhesive layer 11 may be half-cut to remove the inclined portion 13 provided at one end in the width direction of the adhesive layer 11, and a cut surface 14 may be formed at the end of this end portion 12 (see FIG. 8), or the cut surface 14 cut in the thickness direction of the adhesive layer 11 may be formed at the end of the inclined portion 13 (see FIG. 9).

[0082] In the slitting step, the slitting may be performed for each stripe of the adhesive layer 11 or for each plurality of stripes. That is, a plurality of stripes of the adhesive layer 11 may be formed on the release-treated film 10 of the connecting film 2.

[0083] 13 , the connection film 2 may be configured as a film roll 31, or may be configured as a sheet in which one or more adhesive layers 11 are arranged on a release-treated film 10 so as to correspond to one first electronic component 3 (see also FIG. 2 and the relevant description in JP 2023-125888 A). Furthermore, the sheet-like connection film 2 may be configured in such a way that one connection film 2 is arranged for one first electronic component 3, or in such a way that one connection film 2 is arranged for two or more first electronic components 3.

[0084] Fig. 14 is a cross-sectional view showing another example of a laminated structure of a conductive adhesive layer 19 and an insulating adhesive layer 20. The connecting film 2 shown in Fig. 14 has an insulating adhesive layer 20 provided across the entire width of a release-treated film 10, and an adhesive layer 41A formed on the insulating adhesive layer 20 by laminating a conductive adhesive layer 19 with a width smaller than that of the insulating adhesive layer 20. In the adhesive layer 41A, the conductive adhesive layer 19 is laminated at approximately the center in the width direction of the insulating adhesive layer 20.

[0085] 15 is a plan view illustrating a manufacturing example of the connection film 2 shown in FIG. 14. As shown in FIG. 15, a resin composition for an insulating adhesive layer 20 is applied to the entire surface of a release-treated film 10 and dried to provide the insulating adhesive layer 20. A resin composition for a conductive adhesive layer 19 is applied to the insulating adhesive layer 20 in the longitudinal direction with a width smaller than the slit width s and dried to form multiple adhesive layers 41A arranged in parallel. The release-treated film 10 and the insulating adhesive layer 20 are then slit to form gaps between the adhesive layers 41A. In the example shown in FIG. 15, slits S1 to S5 are made in the longitudinal direction of the release-treated film 10 along the film width direction.

[0086] 15, a connecting film 2 made of adhesive layer 41A having a conductive adhesive layer 19 with a width smaller than the slit width (the width of insulating adhesive layer 20) can be manufactured in a single slitting step, and a narrow connecting film 2 can be manufactured more easily than a manufacturing method that combines half-cutting and slitting. In addition, because conductive adhesive layer 19 does not come into contact with the slit blade, it is expected that adhesion problems will be easily avoided.

[0087] Also, as shown in Figure 16, the adhesive layer 41A may be produced by forming a conductive adhesive film 42 in which a conductive adhesive layer 19 is supported on a film-like release substrate, and similarly forming an insulating adhesive film 43 in which an insulating adhesive layer 20 is supported on a release-treated film 10, and then bonding the conductive adhesive layer 19 of the conductive adhesive film 42 and the insulating adhesive layer 20 of the insulating adhesive film 43 together.

[0088] The conductive adhesive film 42 is formed by applying the resin composition of the conductive adhesive layer 19 onto a release substrate using a bar coater, a coating device, or the like, and then drying the resin composition on the release substrate using a heat oven, a heating drying device, or the like, to form a conductive adhesive layer 19 of a predetermined thickness. The same is true for the insulating adhesive film 43. The conductive adhesive film 42 and the insulating adhesive film 43 are passed through a laminating device 44 to be laminated together, and then wound up to produce a connection film 2 having an adhesive layer in which the conductive adhesive layer 19 and the insulation 20 are laminated.

[0089] In addition, the manufacturing method of the connection film 2 is not limited to the above-mentioned method, and the connection film 2 may also be produced by bonding a rectangular film of the conductive adhesive layer 19 cut to an arbitrary width and a film of the insulating adhesive layer 20 supported on an insulating release treatment film 10.

[0090] Fig. 17 is a cross-sectional view showing a modified example of the adhesive layer 41. The connecting film 2 shown in Fig. 17 has a conductive adhesive layer 19 provided across the entire width of the release-treated film 10, and an adhesive layer 41B formed on the conductive adhesive layer 19 by laminating an insulating adhesive layer 20 with a width smaller than that of the conductive adhesive layer 19. A manufacturing example of the adhesive layer 41B is similar to that of the adhesive layer 41A.

[0091] In the connecting film 2, the conductive adhesive layer 19 may be formed at approximately the center in the width direction of the insulating adhesive layer 20, as in the adhesive layer 41A shown in Fig. 14, but it may be biased to either the left or right as shown in Fig. 18. In the connecting film 2 shown in Fig. 18, the insulating adhesive layer 20 is provided over the entire width of the release-treated film 10, and an adhesive layer 41C is formed on the insulating adhesive layer 20, with the conductive adhesive layer 19 laminated with a width smaller than the width of the insulating adhesive layer 20. In the example shown in Figure 18, the adhesive layer 41C is biased to the left side (one side) of the insulating adhesive layer 20 in the width direction, and the conductive adhesive layer 19 is laminated thereon, so that a single-layer region 45 of the insulating adhesive layer 20 where the conductive adhesive layer 19 is not formed is provided on the right end side (other side) of the conductive adhesive layer 19, and the left end (one side) of the conductive adhesive layer 19 is approximately flush with the release treatment film 10 and the left end (one side) of the insulating adhesive layer 20 (it is positioned close to the left end side (one side) of the insulating adhesive layer 20).

[0092] In this way, by using a connection film 2 in which an adhesive layer 41C is formed on an insulating adhesive layer 20, in which a conductive adhesive layer 19 with a width smaller than the width of the insulating adhesive layer 20 is biased to one side in the width direction, even if the adhesive layer 41C melts and flows when connecting the first and second electronic components 3, 4, it is possible to suppress short circuits between terminals due to the accumulation of conductive particles.

[0093] That is, assuming that the second electronic component 4 is a flexible substrate or the like, the molten adhesive layer 41C may flow onto the insulating protective film (solder resist) on the wiring pattern formed at the connection end of the flexible substrate. If the conductive particles contained in the adhesive layer are blocked by the insulating protective film, they may remain in one place, potentially causing electrical continuity between the terminals. However, by arranging the single-layer region 45 of the insulating adhesive layer 20 facing the flexible substrate, the adhesive layer 41C contains almost no conductive particles, even if it flows to the insulating protective film, thereby preventing the conductive particles from remaining and shorting between the terminals.

[0094] In adhesive layer 41C shown in Fig. 18, the ratio (20W:19W) of width 20W of insulating adhesive layer 20 to width 19W of conductive adhesive layer 19 is preferably 11:10 to 18:1, and particularly preferably 9:7 to 18:1. In addition, in adhesive layer 41C shown in Fig. 18, the ratio (20W:45W) of width 20W of insulating adhesive layer 20 to width 45W of single-layer region 45 is preferably 11:1 to 18:17, and particularly preferably 9:2 to 18:17.

[0095] 19, the connection film 2 may have a conductive adhesive layer 19 provided across the entire width of the release-treated film 10, and an adhesive layer 41D formed on the conductive adhesive layer 19 by laminating an insulating adhesive layer 20 with a width smaller than that of the conductive adhesive layer 19 and biased to one side in the width direction of the conductive adhesive layer 19. In the example shown in FIG. 19, the adhesive layer 41D has the insulating adhesive layer 20 biased to the left side (one side) of the conductive adhesive layer 19 in the width direction, so that a single-layer region 46 of the conductive adhesive layer 19 where the insulating adhesive layer 20 is not formed is provided on the right end side (other side) of the insulating adhesive layer 20, and the left end (one side) of the insulating adhesive layer 20 is approximately flush with the release-treated film 10 and the left end (one side) of the conductive adhesive layer 19 (positioned close to the left end side (one side) of the conductive adhesive layer 19).

[0096] By using a connection film 2 having an adhesive layer 41D formed thereon, even if the adhesive layer 41D melts and flows during connection of the first and second electronic components 3 and 4, the amount of resin flow itself is reduced, suppressing the outflow of conductive particles and enabling stable particle capture by the terminals. That is, as described above, assuming that the second electronic component 4 is a flexible substrate or the like, the molten adhesive layer 41D may flow all the way to the insulating protective film (solder resist) on the wiring pattern formed at the connection end of the flexible substrate. Since the adhesive layer 41D has one widthwise side of the insulating adhesive layer 20 removed, the amount of resin flow is small, and the amount of conductive particles flowing with the resin is also suppressed. Therefore, because the amount of particle flow is suppressed, more particles remain on the terminals, resulting in stable conductivity.

[0097] The manufacturing examples of adhesive layers 41C and 41D are the same as those of adhesive layers 41A and 41B. In addition, in adhesive layer 41D shown in Fig. 19, the preferred ratio of width 19W of conductive adhesive layer 19 to width 20W of insulating adhesive layer 20 (19W:20W) and the preferred ratio of width 19W of conductive adhesive layer 19 to width 46W of single-layer region 46 (19W:46W) are the same as those of adhesive layer 41C.

[0098] Furthermore, the connecting film 2 may have one or both widthwise ends of the insulating adhesive layer 20 or the conductive adhesive layer 19 formed on the release-treated film 10 removed. Figure 20 is a cross-sectional view showing, as an example, an adhesive layer 41E from which both widthwise ends of the insulating adhesive layer 20 formed on the release-treated film 10 have been removed. Figure 21 is a cross-sectional view showing, as an example, an adhesive layer 41F from which both widthwise ends of the conductive adhesive layer 19 formed on the release-treated film 10 have been removed. There are no particular restrictions on the extent of removal as long as 50% or more of the central portions of both ends remain.

[0099] By using a connection film 2 having an adhesive layer 41E formed thereon, even if the adhesive layers 41E and 41F melt and flow during connection of the first and second electronic components 3 and 4, the amount of resin flow itself is reduced, thereby preventing short circuits between terminals due to the retention of conductive particles. That is, as described above, assuming that the second electronic component 4 is a flexible substrate or the like, the molten adhesive layer 41E may flow all the way to the insulating protective film (solder resist) on the wiring pattern formed at the connection end of the flexible substrate. Since the adhesive layer 41E has one or both widthwise sides of the insulating adhesive layer 20 removed, the amount of resin flow is small, and the amount of conductive particles flowing with the resin is also suppressed. Therefore, the retention of conductive particles and short circuits between terminals due to the conductive particles being blocked by the insulating protective film can be suppressed. In this way, the influence of resin flow can be controlled by adjusting the amount of resin that affects the flow.

[0100] Furthermore, by using a connection film 2 having an adhesive layer 41F formed thereon, even if the adhesive layer 41F melts and flows during connection of the first and second electronic components 3 and 4, the amount of resin flow itself is reduced, suppressing the outflow of conductive particles and enabling stable particle capture by the terminals. That is, as described above, assuming that the second electronic component 4 is a flexible substrate or the like, the molten adhesive layer 41F may flow all the way to the insulating protective film (solder resist) on the wiring pattern formed at the connection end of the flexible substrate. In this case, because the adhesive layer 41F has one or both widthwise sides of the insulating adhesive layer 20 removed, the amount of resin flow is small, and the amount of conductive particles flowing with the resin is also suppressed. Therefore, because the amount of particle flow is suppressed, more particles remain on the terminals, resulting in stable conductivity. In other words, the effects of resin flow can be controlled by adjusting the amount of resin that affects the flow.

[0101] The insulating adhesive layer 20 in the adhesive layers 41E and 41F can be formed, for example, by applying a resin composition for the insulating adhesive layer 20 over the entire surface of the release-treated film 10, drying it to provide the insulating adhesive layer 20, and then performing half-cutting to remove part of the insulating adhesive layer 20 along the longitudinal direction of the release-treated film 10. In half-cutting, only the insulating adhesive layer 20 is cut with a V-shaped blade without cutting the release-treated film 10, and unnecessary parts are removed by punching or the like.

[0102] Thereafter, the conductive adhesive layer 19 is laminated with a width smaller than that of the insulating adhesive layer 20. The conductive adhesive layer 19 may be formed before the half-cutting process.

[0103] Alternatively, the insulating adhesive layer 20 in the adhesive layers 41E and 41F may be formed by printing a resin composition of the insulating adhesive layer 20 on the release treated film 10 by screen printing or inkjet printing, and then drying it.

[0104] First Example A first example of the present technology will be described below. In the first example, the following connection film, evaluation substrate, and evaluation FPC were prepared.

[0105] (Connection Film) Five parts by mass of resin-core conductive particles (Ni (undercoat) / Au (surface) plating, resin core) having an average particle size of 20 μm and 95 parts by mass of an insulating binder were added to a planetary stirring device (product name: Awatori Rentaro, manufactured by THINKY Corporation) and stirred for one minute to prepare an anisotropic conductive paste.

[0106] The insulating binder was a mixed solution of ethyl acetate and toluene containing 47 parts by mass of phenoxy resin (trade name: YP-50, manufactured by Shin-Nichika Epoxy Manufacturing Co., Ltd.), 3 parts by mass of monofunctional monomer (trade name: M-5300, manufactured by Toagosei Co., Ltd.), 25 parts by mass of urethane resin (trade name: UR-1400, manufactured by Toyobo Co., Ltd.), 15 parts by mass of rubber component (trade name: SG80H, manufactured by Nagase ChemteX Corporation), 2 parts by mass of silane coupling agent (trade name: A-187, manufactured by Momentive Performance Materials Japan), and 3 parts by mass of organic peroxide (trade name: Nyper BW, manufactured by NOF Corporation) so that the solid content was 50% by mass.

[0107] The prepared anisotropic conductive paste was applied to a release-treated film (PET) by screen printing using a screen mask shaped to match the mounting surface of the evaluation board, and then dried to produce a 25 μm thick solid stripe of adhesive layer. At this time, by changing the printing pressure conditions from the standard condition of 0.3 MPa to 0.15 MPa, connection films with two types of slope width (blur width) were produced. The sample with a small slope width (less than 50 μm) set at the standard printing pressure condition of 0.3 MPa was designated as connection film A, and the sample with a large slope width (50 μm or more) set at the printing pressure of 0.15 MPa was designated as connection film B. The release-treated film was then sliced ​​into stripes to obtain connection films.

[0108] For connection film A, an adhesive layer was prepared as shown in Fig. 22(A), and then one side of the connection film had a cut surface cut in the thickness direction by a slit, and the other side had a sloped portion specific to printing, as shown in Fig. 22(B). The width of the adhesive layer of connection film A was 400 μm, and the width of the sloped portion was 50 μm or less.

[0109] 23A and 23B, connection film B was also a connection film with a linear shape on one side and a printing-specific inclined portion on the other side. The width of the adhesive layer of connection film B was 400 μm, and the width of the inclined portion was 50 μm or more. In addition, a cut surface was formed in the thickness direction of the inclined portion on one side by a slit.

[0110] (Evaluation Substrate) An alumina ceramic substrate (tungsten wiring: line / space = 100 μm / 100 μm, wiring height: 10 μm, substrate thickness: 0.4 mm) was prepared as the evaluation substrate to which the connection film was attached. As shown in Fig. 24, the evaluation substrate had multiple terminals arranged near the side edge, and a film-like adhesive layer was attached to the terminal row along the side edge.

[0111] (Evaluation FPC) A flexible printed circuit board (copper wiring: line / space=100 μm / 100 μm, terminal height: 12 μm, polyimide thickness: 25 μm) was prepared as an evaluation FPC to be connected to an evaluation substrate via a connection film.

[0112] The adhesive layer of the connection film according to the examples and comparative examples was bonded to an evaluation substrate, and then the evaluation FPC was mounted and subjected to thermocompression bonding (temperature: 140°C, pressure: 1 MPa, time: 6 seconds) to produce a connection structure. The connection structure was evaluated for electrical connection and insulating binder protrusion. Electrical connection was evaluated as OK if all of the 30 channels formed between the evaluation substrate and the evaluation FPC were conductive, and NG if one or more channels were not conductive. Regarding insulating binder protrusion, if the insulating binder did not flow outside the evaluation substrate when connecting the evaluation FPC, it was evaluated as OK, and if it flowed outside the evaluation substrate, it was evaluated as NG. Overall evaluation was performed by evaluating both electrical connection and insulating binder protrusion as OK, and NG if either one was NG.

[0113] 25A, the side edge of the evaluation substrate was aligned with the edge of the adhesive layer on the sloped portion using connecting film A, and then the evaluation FPC was mounted. In this case, electricity was passed and electrical connection was established regardless of the distance between the sloped portions (30 / 30ch: OK). Furthermore, no protrusion of the insulating binder was observed (protrusion: OK).

[0114] 25(B), the side edge of the terminal of the evaluation board was aligned with the side edge of the inclined portion of the adhesive layer using connecting film A, and then the evaluation FPC was mounted. In this case, even though the inclined portion was on the terminal, electricity was passed through without any problems and an electrical connection was established (30 / 30ch: OK). Furthermore, no protrusion of the insulating binder was observed (protrusion: OK).

[0115] 25(C), the side edge of the evaluation substrate was aligned with the inclined end of the adhesive layer using connecting film B, and then the evaluation FPC was mounted. In this case, electricity was passed through without any problems and an electrical connection was established (30 / 30ch: OK). Furthermore, no protrusion of the insulating binder was observed (protrusion: OK).

[0116] 25(D), the side edge of the terminal of the evaluation board was aligned with the side edge of the inclined portion of the adhesive layer using connection film B, and then the evaluation FPC was mounted. In this case, since there were no conductive particles in the inclined portion, the particles were not captured, resulting in terminals that could not be electrically connected (28 / 30ch: NG). No protrusion of the insulating binder was observed (protrusion: OK).

[0117] 25(E), connecting film B was used to temporarily attach the evaluation substrate so that the inclined portion protruded from the side edge, and then the evaluation FPC was mounted. In this case, electricity was passed through without any problems and an electrical connection was established (30 / 30ch: OK), but protrusion of the insulating binder from the evaluation substrate was observed (protrusion: NG).

[0118]

[0119] As shown in Table 1, controlling the width of the inclined portion can establish a good connection between the terminals provided near the side edges of the substrate and the electronic components, while preventing the extrusion of the insulating binder. It can also be seen that even when the inclined portion width is relatively wide, the amount of insulating binder in the inclined portion is small, preventing extrusion. Furthermore, controlling the width of the inclined portion reduces the effect of resin flow during the connection process, preventing a decrease in the capture rate of conductive particles or disturbance of their arrangement, and providing good connectivity.

[0120] Second Example Next, a second example of the present technology will be described. In the second example, a connecting film without an inclined portion was prepared (see FIG. 5). The same evaluation substrate as in the first example was used.

[0121] [Example 4] An evaluation IC was used as an electronic component to be connected to an evaluation substrate. The same anisotropic conductive paste as in Example 1 was prepared, and a connecting film was produced using the same screen printing and slitting processes as in Example 1, with an adhesive layer having a width of 1.8 mm, a thickness of 25 μm, and a sloped portion width of 200 μm.

[0122] The adhesive layer of the connection film according to Example 4 was attached to an evaluation substrate, and then an evaluation IC was mounted thereon and thermocompression bonded (temperature: 140°C, pressure: 60 MPa, time: 6 seconds) to produce a connection structure. The fillet width (mm) of the connection structure was measured and found to be 310 μm.

[0123] [Example 5] An evaluation FPC was used as an electronic component to be connected to an evaluation substrate. The same anisotropic conductive paste as in Example 1 was prepared, and a connecting film was produced using the same screen printing and slitting processes as in Example 1, with an adhesive layer having a width of 2.0 mm, a thickness of 25 μm, and a sloped portion width of 200 μm.

[0124] The adhesive layer of the connection film according to Example 5 was attached to an evaluation substrate, and then the evaluation FPC was mounted and subjected to thermocompression bonding (temperature: 140°C, pressure: 1 MPa, time: 6 seconds) to produce a connection structure. The fillet width (mm) of the connection structure was measured and found to be 90 μm.

[0125] Comparative Example 3 The same evaluation IC as in Example 3 was used as an electronic component to be connected to the evaluation substrate. The same anisotropic conductive paste as in Example 1 was prepared, and a connection film was produced with an adhesive layer having a width of 1.8 mm and a thickness of 25 μm through the same screen printing and slitting processes as in Example 1. The connection film of Comparative Example 3 did not have an inclined portion.

[0126] The adhesive layer of the connection film according to Comparative Example 3 was attached to an evaluation substrate, and then an evaluation IC was mounted thereon and thermocompression bonded (temperature: 140°C, pressure: 60 MPa, time: 6 seconds) to produce a connection structure (see FIG. 6). The fillet width (mm) of the connection structure was measured and found to be 460 μm.

[0127] Comparative Example 4 The same evaluation FPC as in Example 4 was used as an electronic component to be connected to the evaluation substrate. The same anisotropic conductive paste as in Example 1 was prepared, and a connection film was produced with an adhesive layer having an adhesive layer width of 2.0 mm and an adhesive layer thickness of 25 μm, as in Comparative Example 3. The connection film of Comparative Example 4 did not have an inclined portion.

[0128] The adhesive layer of the connection film according to Comparative Example 4 was attached to an evaluation substrate, and then the evaluation FPC was mounted and subjected to thermocompression bonding (temperature: 140°C, pressure: 1 MPa, time: 6 seconds) to produce a connection structure. The fillet width (mm) of the connection structure was measured and found to be 280 μm.

[0129]

[0130] As shown in Table 2, Example 4, which used a connecting film with an inclined portion, formed a narrower fillet when the same evaluation IC was connected than Comparative Example 3, which used a connecting film without an inclined portion. Similarly, Example 5, which used a connecting film with an inclined portion, formed a narrower fillet when the same evaluation FPC was connected than Comparative Example 4, which used a connecting film without an inclined portion.

[0131] Therefore, by using a connection film with an inclined portion, a fillet can be formed using the amount of resin required for connection, regardless of the type of second electronic component (IC, FPC), eliminating unnecessary resin and suppressing the spread of the fillet, making it easier to accommodate higher density mounting areas and enabling the mounting of a large number of miniaturized electronic components.

[0132] REFERENCE SIGNS LIST 1 Connection structure, 2 Connection film, 3 First electronic component, 4 Second electronic component, 5 First terminal, 6 Second terminal, 10 Release treatment film, 11 Adhesive layer, 11A Hardened film, 12 Main body portion, 13 Inclined portion, 16 Substrate side edge, 17 Cushioning material, 18 Crimping tool, 19 Conductive adhesive layer, 20 Insulating adhesive layer, 21 Adhesive, 22 Squeegee, 23 Screen mask

Claims

1. A method for manufacturing a connection structure in which a first terminal of a first electronic component having a first terminal and a second terminal of a second electronic component having a second terminal are connected by a cured film formed by curing an adhesive layer of a connection film, the method comprising: an attachment step of attaching the adhesive layer of the connection film to the first electronic component; an arrangement step of arranging the second terminal on the first terminal via the adhesive layer; and a connection step of pressing the second electronic component and curing the adhesive layer, wherein the adhesive layer has a main body portion having a predetermined thickness and tapered inclined portions formed on both ends of the main body portion in the width direction, and in the attachment step, the main body portion is attached to the first terminal in line with the adhesive layer in the width direction.

2. The method for manufacturing a connection structure according to claim 1, wherein the adhesive layer is a conductive adhesive layer containing conductive particles or an insulating adhesive layer not containing conductive particles.

3. The method for manufacturing a connection structure according to claim 1, wherein the adhesive layer comprises a conductive adhesive layer containing conductive particles and an insulating adhesive layer not containing conductive particles.

4. A method for manufacturing a connection structure according to claim 1 or 2, wherein the width of the adhesive layer is less than 0.5 mm.

5. A method for manufacturing a connection structure as described in claim 1 or 2, wherein in the attachment process, the first terminal is formed near the side edge of the first electronic component, and the side edge of the first electronic component is aligned with the end of the inclined portion and attached.

6. A connection film comprising: a release-treated film; and an adhesive layer laminated along the longitudinal direction of the release-treated film, wherein the adhesive layer has a main body portion having a predetermined thickness and tapered inclined portions formed on both ends of the main body portion in the width direction, and the width of the inclined portions is 5% to 20% of the width of the adhesive layer.

7. The connecting film according to claim 6, wherein the width of the adhesive layer is 50% to 95% of the width of the release-treated film.

8. The connecting film according to claim 6, wherein the width of the adhesive layer is less than 0.5 mm.

9. A connection film according to any one of claims 6 to 8, wherein the adhesive layer is a conductive adhesive layer containing conductive particles or an insulating adhesive layer not containing conductive particles.

10. A connection film according to any one of claims 6 to 8, wherein the adhesive layer comprises a conductive adhesive layer containing conductive particles and an insulating adhesive layer not containing conductive particles.

11. A connection film according to any one of claims 6 to 8, wherein the end of one of the inclined portions is a cut surface in the thickness direction, and the end of the other inclined portion is an inclined surface facing the release-treated film.

12. A connection film according to any one of claims 6 to 8, wherein the adhesive layer is formed in the form of a continuous dashed or dotted line of individual pieces of adhesive having a predetermined length spaced apart at a fixed distance.

13. A connection film as described in claim 10, wherein the insulating adhesive layer is formed across the entire width of the release-treated film, and the conductive adhesive layer is laminated on the insulating adhesive layer with a width smaller than the width of the insulating adhesive layer.

14. The connecting film according to claim 13, wherein the conductive adhesive layer is formed at approximately the center in the width direction of the insulating adhesive layer.

15. A connection film as described in claim 13, wherein the conductive adhesive layer is formed biased to one side of the width direction of the insulating adhesive layer, and a single-layer region of the insulating adhesive layer is provided on the other side of the width direction of the insulating adhesive layer.

16. The connecting film according to claim 13, wherein one or both widthwise ends of the insulating adhesive layer are removed.

17. A connection film as described in claim 10, wherein the conductive adhesive layer is formed across the entire width of the release-treated film, and the insulating adhesive layer is laminated on the conductive adhesive layer with a width smaller than the width of the conductive adhesive layer.

18. The connecting film according to claim 17, wherein the insulating adhesive layer is formed at approximately the center in the width direction of the conductive adhesive layer.

19. A connection film as described in claim 17, wherein the insulating adhesive layer is formed biased to one side of the width direction of the conductive adhesive layer, and a single-layer region of the conductive adhesive layer is provided on the other side of the width direction of the conductive adhesive layer.

20. The connecting film according to claim 17, wherein one or both widthwise ends of the conductive adhesive layer are removed.

21. A method for manufacturing a connecting film, comprising: an adhesive layer forming step of applying an adhesive in a predetermined shape onto a release-treated film and forming a plurality of adhesive layers in stripes on the release-treated film; and a slitting step of slitting the release-treated film to a predetermined width according to the adhesive layers, wherein the adhesive layer has a main body portion having a predetermined thickness and tapered inclined portions formed on both ends of the main body portion in the width direction, and the adhesive layer is cut so that the width of the inclined portions is 5% to 20% of the width of the adhesive layer.

22. The method for manufacturing a connecting film according to claim 21, wherein the release-treated film is slit into one or more adhesive layers.

23. The method for manufacturing a connecting film according to claim 21, wherein the width of the adhesive layer is less than 0.5 mm.

24. The method for manufacturing a connection film according to any one of claims 21 to 23, wherein the connection film has a conductive adhesive layer containing conductive particles.

25. The method for producing a connecting film according to claim 24, wherein the adhesive layer comprises an insulating adhesive layer that does not contain conductive particles.

26. A method for manufacturing a connection film according to any one of claims 13 to 15, wherein the adhesive layer is formed in the form of a continuous dashed or dotted line of individual pieces of adhesive having a predetermined length spaced apart at a fixed distance.

27. A method for manufacturing a connection film as described in claim 25, wherein the insulating adhesive layer is formed across the entire width of the release-treated film, and the conductive adhesive layer is laminated on the insulating adhesive layer with a width smaller than the width of the insulating adhesive layer.

28. The method for manufacturing a connecting film according to claim 27, wherein the conductive adhesive layer is formed at approximately the center in the width direction of the insulating adhesive layer.

29. A method for manufacturing a connection film as described in claim 27, wherein the conductive adhesive layer is formed biased to one side of the width direction of the insulating adhesive layer, and a single-layer region of the insulating adhesive layer is provided on the other side of the width direction of the insulating adhesive layer.

30. The method for producing a connecting film according to claim 27, wherein one or both widthwise ends of the insulating adhesive layer are removed.

31. A method for manufacturing a connection film as described in claim 25, wherein the conductive adhesive layer is formed across the entire width of the release-treated film, and the insulating adhesive layer is laminated on the conductive adhesive layer with a width smaller than the width of the conductive adhesive layer.

32. The method for manufacturing a connecting film according to claim 31, wherein the insulating adhesive layer is formed at approximately the center in the width direction of the conductive adhesive layer.

33. A method for manufacturing a connection film as described in claim 31, wherein the insulating adhesive layer is formed biased to one side in the width direction of the conductive adhesive layer, and a single-layer region of the conductive adhesive layer is provided on the other side in the width direction of the conductive adhesive layer.

34. The method for producing a connecting film according to claim 31, wherein one or both widthwise ends of the conductive adhesive layer are removed.

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