Connection structure

Abstract

A connection structure (1), which connects an electrode (11) of an electronic component (10) and an electrode (21) of a substrate (20) by means of a connection material (2 ') derived from a conductive particle-containing layer in which conductive particles are held in a binder material, is provided in a planar view with respect to a connection surface between the electrode (11) of the electronic component (10) and the electrode (21) of the substrate (20). A region 5'in which a connecting material 2 'derived from a conductive particle-containing layer is not present is provided between adjacent electrodes 11a, 11b in an electronic component 10. In a method for manufacturing a connection structure (1), a connection material (2) in which conductive particles are held in a binder material is disposed on an electrode (11) of an electronic component (10) or on an electrode (21) of a substrate (20), and a region (5) in which the connection material (2) is not present is formed between adjacent electrodes (11a, 11b) within the electronic component (10) or between adjacent electrodes (21a, 21b) within the substrate (20). The connecting material (2) is sandwiched by the electrodes (11, 21) and is crimped or the like.

Description

Technical Field

[0001] The present invention relates to a connection structure for connecting electronic components such as tiny light-emitting elements to a substrate using conductive particles, a manufacturing method thereof, and a connection material used in the manufacturing method. Background Art

[0002] A μLED display formed by arranging μLEDs, which are tiny light-emitting elements, on a substrate can omit the backlight required for a liquid crystal display, thereby enabling the display to be thinned, and is expected to be a display or light source that can also achieve wide color gamut, high definition, and power saving.

[0003] As a method for manufacturing a display on which μLEDs are arranged, Patent Document 1 describes the following: using a transfer head to pick up red, blue, and green μLED arrays formed on a carrier substrate, arranging them on a transfer target substrate such as a display substrate, bonding the μLED arrays to the transfer target substrate by deposition of a solder layer, and then forming contact lines thereon using ITO or the like.

[0004] In addition, Patent Document 2 describes the following method: laminating an anisotropic conductive film on an LED electrode formed on a wafer, cutting it to form an LED chip, holding the LED chip with a convex embossed holding member, and arranging the LED chip on a circuit substrate to manufacture a light-emitting substrate. According to this method, since an anisotropic conductive film has already been formed on the electrode of the LED chip, unnecessary anisotropic conductive films can be reduced.

[0005] In Patent Document 3, as a method for mounting an LED on a substrate, the following method is described: forming bump electrodes on the substrate in advance, and patterning a semi-cured adhesive layer around the LED mounting portion in advance, then mounting the LED on the substrate, bringing the bump electrodes into contact with the electrodes of the LED, and curing the semi-cured adhesive layer around the LED. According to this method, there is no adhesive between the electrode of the LED and the electrode of the substrate, so contact failure caused by the adhesive can be avoided. Prior Art Documents Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-500562 Patent Document 2: Japanese Patent Application Laid-Open No. 2020-191419 Patent Document 3: Japanese Patent Application Laid-Open No. 2021-9985 Summary of the Invention Problems to be Solved by the Invention

[0007] However, for the high refinement of the display, the size of the μLED is reduced. Along with this, the size of the μLED electrode is also reduced. If the interval between the electrodes is narrowed, the risk of short circuit or poor connection increases in the above prior art.

[0008] In addition, in the method described in Patent Document 2, after holding the LED in a convex imprint-shaped holding member, the LED is arranged on the substrate. Therefore, from the viewpoint of productivity, it is sometimes not suitable for arranging LEDs over a large range. In addition, since a thermosetting resin is used in the anisotropic conductive film, the LED chips cannot be singulated by etching and arranged on the circuit substrate.

[0009] In the method described in Patent Document 3, bump electrodes are formed on the substrate in advance, so it is difficult to cause a short circuit. However, it takes time to form the bump electrodes, and it is not suitable for mass production. In addition, it is difficult to control the patterning of the semi-cured adhesive layer.

[0010] In contrast, the problem of the present invention is to provide a connection structure for connecting electronic components such as a minute light-emitting element to a substrate, which suppresses short circuit or poor conduction, a manufacturing method of such a connection structure, and a connection material used in the manufacturing method. Means for Solving the Problem

[0011] The present inventors have completed the present invention by considering the following: When installing an electronic component, if first between the electrode of the electronic component and the electrode of the substrate, a high density of conductive particles is held in a layered adhesive material and exists, and a region where the adhesive material and the connection material derived from the conductive particle-containing layer do not exist is formed between adjacent electrodes in the electronic component, and then thermocompression bonding or the like is performed, reliable electrical connection can be achieved even if the electronic component is miniaturized, and a short circuit will not occur.

[0012] That is, the present invention provides a connection structure that connects the electrodes of opposing electronic components and the electrodes of the substrate through a connection material derived from a conductive particle-containing layer in which conductive particles are held in an adhesive material. When viewed from above the connection surface of the electrodes of the electronic component and the electrodes of the substrate, a region where the connection material derived from the conductive particle-containing layer does not exist is provided between adjacent electrodes in the electronic component.

[0013] In addition, the present invention provides a method for manufacturing a connection structure, which is the method for manufacturing the above-described connection structure. A conductive particle-containing layer in which conductive particles are held in an adhesive material is formed on an electrode of an electronic component or an electrode of a substrate, and a region where there is no connection material derived from the conductive particle-containing layer is formed between adjacent electrodes in the electronic component or between corresponding electrodes of the substrate. The conductive particle-containing layer is sandwiched between the electrode of the electronic component and the electrode of the substrate, and connection is performed by at least heating or pressurizing.

[0014] Furthermore, the present invention provides a conductive particle-containing film used in the method for manufacturing the above-described connection structure, which holds conductive particles in a film-shaped adhesive material. Advantages of the Invention

[0015] In the connection structure of the present invention, when viewed from above the connection surface between the electrode of the electronic component and the electrode of the substrate, there is a region between adjacent electrodes in the electronic component where there is no connection material derived from the conductive particle-containing layer in which conductive particles are held in the adhesive material. In other words, according to the connection structure of the present invention, the opposing electrodes of the electronic component and the substrate are reliably connected by the connection material derived from the conductive particle-containing layer, and there is a region between adjacent electrodes in the electronic component where there is no connection material derived from the conductive particle-containing layer, thereby preventing short circuits.

[0016] In addition, according to the manufacturing method of the present invention, the connection structure of the present invention can be reliably manufactured. Furthermore, according to the conductive particle-containing film of the present invention, since conductive particles are held in a film-shaped adhesive material, the conductive particle-containing film of the present invention is made into a single sheet and disposed on the electrode of the electronic component or the electrode of the substrate by a laser lift-off method, a transfer method using an imprint material, etc., thereby enabling the manufacturing method of the present invention to be simply implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A It is a longitudinal sectional view illustrating the manufacturing process of the connection structure of the embodiment. Figure 1B It is a longitudinal sectional view illustrating the manufacturing process of the connection structure of the embodiment. Figure 1C It is a cross-sectional view (X-X view) of the electrode portion during the manufacturing process of the connection structure of the embodiment. Figure 2 It is a longitudinal sectional view illustrating the manufacturing process of the connection structure of the embodiment. Figure 3A It is a longitudinal sectional view of the connection structure of the embodiment. Figure 3B It is a cross-sectional view (Y-Y view) of the electrode portion in the connection structure of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In addition, in each figure, the same reference numerals denote the same or equivalent components.

[0019] [Connection structure] Figure 3A is a longitudinal sectional view of the connection structure 1 of an embodiment of the present invention, Figure 3B and is a cross-sectional view (Y - Y view) of its electrode portion. The connection structure 1 is a connection structure in which the electrode 11 of the electronic component 10 and the electrode 21 of the substrate 20 on which the wiring circuit of the electronic component 10 is formed are connected by a connection material 2' derived from a conductive particle-containing layer in which conductive particles are held in an adhesive material.

[0020] Here, as the electronic component 10, for example, a μLED with a side length of less than 50 μm of the chip, a mini LED with a side length of about 50 μm to 200 μm of the chip, etc. can be cited.

[0021] The connection material 2' derived from the conductive particle-containing layer in which conductive particles are held in the adhesive material is formed by heating or pressing at least a conductive particle-containing layer 2 such as a conductive particle-containing film in which conductive particles 3 are held in an adhesive material (adhesive material layer) 4 formed of an adhesive resin, and more specifically, by performing pressing, thermocompression bonding, reflow soldering, etc. corresponding to the type of the conductive particle-containing layer 2. The conductive particle portion 3' of the connection material 2' derived from the conductive particle-containing layer electrically connects the opposing electrodes 11 and 21, and the adhesive material portion 4' of the connection material 2' fixes the opposing electrodes 11 and 21.

[0022] In the connection structure 1 of the present embodiment, when viewed from above the connection surface between the electrode 11 of the electronic component 10 and the electrode 21 of the substrate 20, the area of the connection material 2' derived from the conductive particle-containing layer is equal to or larger than the area of the electrode 11 of the electronic component 10. The connection material 2' derived from the conductive particle-containing layer is characterized in that although it may protrude from the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20, there is a region 5' where the connection material 2' does not exist between adjacent electrodes 11a and 11b within the electronic component 10. Thereby, the electrical connection and fixation between the electrodes 11 and 21 are reliably performed, and there is a region 5' where the connection material 2' does not exist between adjacent electrodes 11a and 11b within the electronic component 10, thus preventing short circuits.

[0023] On the contrary, if the area of the connection material 2' derived from the conductive particle-containing layer is too small, poor conduction is likely to occur and the productivity deteriorates. Further, if there is no region 5' where the connection material 2' derived from the conductive particle-containing layer does not exist between the adjacent electrodes 11a and 11b within the electronic component 10, and the connection material 2' derived from the conductive particle-containing layer completely covers between the adjacent electrodes 11a and 11b, the occurrence of a short circuit is a concern. Further, in the case where the electronic component is an optical element such as a μLED, if there is a connection material 2' derived from the conductive particle-containing layer between the adjacent electronic components 10, an adverse effect on the visual recognition of the connection structure is a concern.

[0024] In the connection structure 1, the minimum width d' of the region 5' where the connection material 2' does not exist is preferably 1 / 4 or more, more preferably 1 / 3 or more, and still more preferably 1 / 2 or more of the inter-electrode distance in order to avoid a short circuit. Specifically, the minimum width d' is preferably 1 μm or more, more preferably 2 μm or more. It may also be set to be equal to or more than the particle diameter, and preferably 2 times or more. In the case where the connection structure 1 of the present invention has a plurality of electronic components 10 that connect the electrodes 11 of the electronic component 10 and the electrodes 21 of the substrate 20 through the connection material 2' derived from the conductive particle-containing layer, it is preferable in terms of avoiding the occurrence of a short circuit that all the electronic components 10 have a region 5' where the connection material 2' does not exist between the adjacent electrodes 11a and 11b within the electronic component 10. On the other hand, considering the case where there are sometimes many connection portions between the electrodes 11 of the electronic component 10 and the electrodes 21 of the substrate 20 continuously present in the connection structure 1, it is desirable in actual use that 90% or more, preferably 95% or more of all the connection portions have the aforementioned region 5'.

[0025] In the connection structure 1 of the present invention, as the proportion of the conductive particle-derived portion 3' in the connection material 2', the lower limit is preferably 20% by volume or more, more preferably 30% by volume or more, and the upper limit is preferably 60% by volume or less, more preferably 50% by volume or less. As will be described later, from the viewpoint of the landing property in the case of landing the conductive particle-containing layer 2 monolithically on the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20 using a laser lift-off device, this proportion corresponds to the case where the preferred content ratio of the conductive particles in the conductive particle-containing layer is 20 to 60% by volume. Further, in the present invention, the content ratio of the conductive particles may exceed 60% by volume, and there is no particular limitation.

[0026] The volume ratio of the conductive particle-derived portion 3' in the connection material 2' of the connection structure 1 described above can be obtained based on microscopic observation and the measured value of the thickness of the connection material 2'.

[0027] On the other hand, regarding the adhesive material portion 4' in the connection material 2' of the connection structure 1, as long as the opposing electrodes 11 and 21 can be fixed, when viewed from above the connection surface, it is preferably 40% or more and 80% or less of the area of the connection material 2'.

[0028] [Manufacturing method of connection structure] As a manufacturing method of the connection structure 1, generally, first, as Figure 1A shown, a conductive particle-containing layer 2 in which conductive particles 3 are held in an adhesive material layer 4 is formed on the electrode 11 of the electronic component 10, or as Figure 1B shown, the same conductive particle-containing layer 2 is formed on the electrode 21 of the substrate 20, and a region 5 where the conductive particle-containing layer 2 does not exist is formed between adjacent electrodes 11a and 11b in the electronic component 10 or between adjacent electrodes 21a and 21b in the substrate 20. Next, the electrode 11 of the electronic component 10 and the electrode 21 of the substrate 20 are aligned, and the conductive particle-containing layer 2 is sandwiched by these electrodes 11 and 21, and at least heated or pressurized to obtain the connection structure.

[0029] Here, the minimum width d of the region 5 where the conductive particle-containing layer 2 does not exist is preferably more than 1 μm, more preferably more than 2 μm. Alternatively, it can also be set to be equal to or more than the particle diameter of the conductive particles 3, and can also be set to be preferably 2 times or more. Thereby, even when thermocompression bonding or the like is performed between the electrodes 11 and 21 sandwiching the conductive particle-containing layer 2, it is difficult to cause a short circuit. In addition, when the connection structure has a plurality of electronic components, it is preferable to form regions 5 with a minimum width exceeding 2 μm in 60% or more of all the electronic components.

[0030] [Method of forming conductive particle-containing layer on electrode] As a method for forming the conductive particle containing layer 2 on the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20, for example, a method can be cited in which the conductive particle containing film is monolithic and is arranged on the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20. In this case, the shape of the monolithic film containing the conductive particles is not particularly limited, and can be appropriately set according to the shape or size of the electrode of the electronic component as the connection object. Regarding the shape of the monolithic film, since it is expected that the quality judgment after being arranged on the electrode becomes easy, it can also be a rectangle (including a square) as the shape of a general electrode. In addition, in the case where the monolithic film containing the conductive particles is arranged on the electrode by the laser stripping method, in order to suppress the occurrence of rolling or defect, it is preferred that the shape of the monolithic film is set to at least one selected from a polygon composed of an obtuse angle, a rounded polygon, an ellipse, an oblong, and a circle. As long as the monolithic film of such a shape does not hinder the connection, a part of it can also protrude from the electrode when connected. It is also possible to provide a single piece of at least one selected from a polygon formed by an obtuse angle, a polygon with rounded corners, an ellipse, an oblong, and a circle at each electrode, and place and connect the micro-LED thereon. It is also possible to pre-set such a single piece at the electrode of the micro-LED. The electrode and the single piece sometimes appear as if a part of each is repeated. It is also possible to be in a state where an electrode of the substrate or an electrode of the micro-LED exists at the end of the single piece. In the case where the insulating resin is insufficient, the present invention also includes providing another single piece of insulating resin and adding it near the electrode of the connecting structure or the outer periphery of the micro-LED.

[0031] As a laser stripping method, a known laser stripping method (for example, Japanese Patent Gazette No. 2017-157724) or a method according to the laser stripping method can be performed. For example, a laser can be irradiated to a conductive particle-containing film, so that a single-sheet film of an area corresponding to the electrode 11 or the electrode 21 is detached from the conductive particle-containing film and lands on the electrode 11 or the electrode 21. In the case where the electronic component 10 is landed on the substrate 20 by the laser stripping method, a silicone rubber layer can also be provided on the substrate 20. The silicone rubber layer can be formed by polydimethylsiloxane (PDMS) or the like. In addition, the laser stripping method can also be used to land the electronic component 10 on a silicone rubber sheet, and in a state where the electronic component 10 is provided on the silicone rubber sheet, the electrode 11 of the electronic component 10 is overlapped with the electrode 21 of the substrate 20.

[0032] The laser lift-off method can be performed using a commercially available laser lift-off apparatus (for example, a laser lift-off apparatus manufactured by Shin-Etsu Chemical Co., Ltd., trade name “Invisi LUM-XTR”).

[0033] Alternatively, a transfer method using a known imprint material (e.g., Japanese Unexamined Patent Application Publication No. 2021-141160) can be used to transfer the conductive particle-containing film onto the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20.

[0034] As a method of forming the conductive particle-containing layer 2 on the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20, a conductive particle-containing paste in which conductive particles are dispersed in an adhesive material can be prepared, and the conductive particle-containing layer 2 can be formed from the conductive particle-containing paste by a printing method such as inkjet or screen printing.

[0035] Regardless of which method is used to form the conductive particle-containing layer 2, in the connection structure 1 that has undergone a connection process such as crimping, it is preferable to adjust the layer thickness or area of the conductive particle-containing layer 2 formed on the electrode 11 or the electrode 21 so that the area of the connection material 2' derived from the conductive particle-containing layer is preferably equal to or greater than the area of the electrode 11 of the electronic component 10 with respect to the area of the electrode 11.

[0036] (Conductive particles) As the type of the conductive particles 3 that constitute the conductive particle-containing layer 2, as long as it is a metal that can achieve conduction between the electrodes 11 and 21, there is no particular limitation, and preferably, Au particles, Ni particles, Ag particles, Cu particles, Sn-based solder particles, etc. can be listed. In addition, it can also be metal-coated resin core particles. The type of the conductive particles can be single or multiple between the electrodes 11 and 21.

[0037] The particle diameter of the conductive particles 3 is preferably 50 μm or less, more preferably 20 μm or less, further preferably 10 μm or less, particularly preferably 3 μm or less, and furthermore, it can also be set to 0.1 μm or less. There is no limitation on the lower limit of the particle diameter. On the other hand, if the particle diameter is too large, it is difficult to use a laser peeling device to separate the single sheet of the conductive particle-containing film from the conductive particle-containing film and land on the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20.

[0038] (Adhesive material) As the resin that constitutes the conductive particle-containing layer 2, a resin used as an insulating resin in known anisotropic conductive films (e.g., Japanese Patent No. 6187665, Japanese Unexamined Patent Application Publication No. 2022-75723, Japanese Unexamined Patent Application Publication No. 2018-90768, etc.) can be used, and a resin having adhesiveness laminated as an adhesive layer on the resin layer that holds the conductive particles is particularly preferably used.

[0039] In addition, it is preferable that a rubber component having cushioning properties is incorporated in the resin constituting the conductive particle-containing layer 2. The rubber component is not particularly limited as long as it is an elastomer having high cushioning properties (impact absorbency). Specific examples include acrylic rubber, silicone rubber, butadiene rubber, polyurethane resin (urethane-based elastomer), and the like.

[0040] When forming the conductive particle-containing layer on the electrode using the laser lift-off method, for the adhesive material before curing (before connection), the durometer A hardness according to JIS K6253 is preferably 20 to 40, more preferably 20 to 35, and further preferably 20 to 30. The storage modulus (temperature 30°C, frequency 200 Hz) obtained by a dynamic viscoelasticity test apparatus (Vibron, A&D Co., Ltd.) according to JIS K7244 is preferably 60 MPa or less, more preferably 30 MPa or less, and further preferably 10 MPa or less.

[0041] In addition, for the adhesive material, the storage modulus at 30°C measured in the tensile mode according to JIS K7244 after curing (after connection) is preferably 100 MPa or more, more preferably 2000 MPa or more. When the storage modulus at 30°C is too low, there is a tendency that good conductivity cannot be obtained and the connection reliability also decreases. The storage modulus can be measured under the measurement conditions of, for example, a frequency of 11 Hz and a heating rate of 3°C / minute in the tensile mode using a dynamic viscoelasticity test apparatus (Vibron, A&D Co., Ltd.).

[0042] In addition, for the adhesive material, the reaction rate before and after laser irradiation is preferably 25% or less, more preferably 20% or less, and further preferably 15% or less. In order to meet this requirement, the type of resin constituting the adhesive material is selected, the concentration of the polymerization initiator is adjusted, and the like. Thereby, the manufacturing conditions can be alleviated and the productivity can be stabilized. For the measurement of this reaction rate, for example, FT-IR can be used to measure the peak heights A, a of reaction groups such as epoxy groups (around 914 cm -1 -1) and (meth)acryloyl groups (around 1635 cm -1 -1), and the reference peak heights B, b of methyl groups (around 2930 cm -1 -1) and the like before and after laser irradiation in the laser lift-off method, and the reaction rate is calculated by the following formula as the reduction rate of the reaction groups. The reaction rate can also be calculated based on the original wafer of a single piece.

[0043] Reaction rate (%) = {1 - (a / b) / (A / B)} × 100 In the formula, A is the peak height of the reaction group before laser irradiation, B is the reference peak height before laser irradiation, a is the peak height of the reaction group after laser irradiation, and b is the reference peak height after laser irradiation.

[0044] (Conductive particle-containing film) The conductive particle-containing film of the present invention is common with the conventional anisotropic conductive films in that conductive particles are held in a resin layer. On the other hand, in the conductive particle-containing film of the present invention, the individual conductive particles can also aggregate, which is different from the conventional anisotropic conductive films in this regard. In addition, as the conductive particle-containing film of the present invention, it is preferable that the adhesive material layer holding the conductive particles does not contain a curable resin.

[0045] The conductive particle-containing film of the present invention cannot connect electrodes with a general fine pitch, which is different from the conventional anisotropic conductive films in this regard. For example, if the conductive particle-containing film of the present invention is disposed between an electronic component (FPC) having an electrode pattern in which strip-shaped electrodes (height: 8 μm) with a width of 10 μm are arranged at a pitch of 20 μm (L / S = 1 / 1) and a glass substrate having a corresponding electrode pattern and thermocompression bonded, since the amount of conductive particles is excessive with respect to the space between the electrodes, a short circuit occurs between the electrodes of the electronic component, and thus conduction characteristics cannot be obtained. Therefore, in the present invention, it is preferable to provide a connection material for each electrode so that adjacent electrodes are separated by a region where no connection material exists.

[0046] In addition, in the conductive particle-containing film of the present invention, since the amount of conductive particles is excessive with respect to the amount of resin, even if an attempt is made to temporarily bond the conductive particle-containing film by a conventional general method, the adhesive force may decrease and the adhesiveness may become unstable. However, by adopting a method of singulating the conductive particle-containing film by using a laser peeling method and placing it on a substrate as a method of using the conductive particle-containing film, the adhesive force of the conductive particle-containing film of the present invention can be lower than that of a normal anisotropic conductive film.

[0047] In addition, when the conductive particles are metal particles such as solder, the opposed electrodes can also be connected by melting the solder.

[0048] In addition, an adhesive layer not containing conductive particles may be laminated on the adhesive material layer holding the conductive particles. Conversely, an adhesive layer not including conductive particles may be provided on the electrode, and then an adhesive material layer containing conductive particles may be provided. As will be described later, bottom filling may also be performed as needed after connection.

[0049] In the conductive particle-containing film of the present invention, regarding the number density of the conductive particles, as an example, the lower limit is 150,000 particles / mm 2 Above, the upper limit is 300,000 particles / mm as long as the adhesiveness of the film is not impaired. 2Hereinafter, in the conductive particle-containing film of the present invention, sometimes it is not suitable to measure the number density of conductive particles by top-down observation of the film because the conductive particles are densely packed. This is different from the conventional anisotropic conductive films in this regard.

[0050] The arrangement of the conductive particles or conductive particle aggregates in the film surface direction (film surface view) in the conductive particle-containing film can be arranged neatly or randomly. Each conductive particle is preferably separated from each other, but in order to increase the number density of conductive particles on the electrode, a plurality of conductive particles can also form units or aggregates. In this case, the aggregates or units can also be separated from each other.

[0051] When the conductive particle-containing film of the present invention is disposed on an electrode, the area occupancy rate of the conductive particles in the electrode is preferably greater than 35%, more preferably 40% or more. Regarding the upper limit of the area occupancy rate, as long as the state can be maintained after the conductive particle-containing film is disposed on the electrode, there is no particular limitation. However, as an example, it is 90% or less, preferably 85% or less.

[0052] Here, the area occupancy rate is calculated by the following formula. Area occupancy rate (%) = [Number density of conductive particles in top-down observation] × [Average value of the top-down observation area of one conductive particle] × 100

[0053] In addition, in the case where there is a lot of aggregation of conductive particles, the area occupancy rate can also be obtained by subtracting the area where no conductive particles are present in top-down observation. The area occupancy rate can be obtained based on microscopic observation.

[0054] The arrangement of the conductive particles in the film thickness direction in the conductive particle-containing film is not particularly limited. From the viewpoint of improving the size or position accuracy in the case where the conductive particle-containing film is singly landed on the electrode using a laser lift-off device, it is preferable that the positions of the conductive particles in the film thickness direction are aligned.

[0055] Regarding the film thickness of the conductive particle-containing film, if the film thickness is too thin, the adhesion between the opposing electrodes 11 and 21 is insufficient; if it is too thick, during the connection process in the manufacturing process of the connection structure, the conductive particles shift in position, and there is a concern about the occurrence of a short circuit or a decrease in the conduction characteristics between the electrodes 11 and 21. Therefore, the film thickness is preferably 0.8 times or more, more preferably 1 time or more, of the particle diameter of the conductive particles 3, and preferably 3 times or less, more preferably 2.5 times or less, and particularly preferably 1.5 times or less.

[0056] (Method for manufacturing the conductive particle-containing film and the conductive particle-containing paste) Regarding the conductive particle-containing film and the conductive particle-containing paste of the present invention, they can be manufactured by known methods. For example, they can also be manufactured according to the methods described in Japanese Patent Application Laid-Open No. 2018-145418, etc., and can also be manufactured by making the conductive particles excessive and reducing the small particle size fillers as compared with that publication. The small particle size fillers can also be set to zero. In addition, in the conductive particle-containing film of the present invention, units in which every two to three conductive particles are close to or in contact with each other can also be formed. In this case, the conductive particle-containing film can be manufactured, for example, according to the anisotropic conductive films described in Japanese Patent No. 6187665 and Japanese Patent Application Laid-Open No. 2016-85983.

[0057] (Connection process) After forming the conductive particle-containing layer 2 holding conductive particles in the adhesive material on the electrode 11 of the electronic component 10 or the electrode 21 of the substrate 20, the electrode 21 or 11 opposed to the electrode 11 or 21 on which the conductive particle-containing layer 2 is disposed is aligned by a conventional method, as Figure 2 shown, with the conductive particle-containing layer 2 sandwiched between the opposed electrodes 11 and 21, and the electrodes 11 and 21 are connected by heating or crimping, etc. The crimping conditions at this time can be appropriately determined according to the types of the conductive particles 3 or the adhesive material (adhesive material layer) 4 constituting the conductive particle-containing layer 2.

[0058] In the connection process, the adhesive material can be thermally cured or photo-cured. In addition, the opposed electrodes 11 and 21 can also be connected by heating and reflow soldering according to the type of the resin constituting the adhesive material.

[0059] By such treatment, the Figure 3A shown connection structure 1 can be obtained. In addition, a underfill process can be further added to strengthen the fixation of the electronic component 10 and the substrate 20. It can also be considered that the present invention is a connection structure similar to a connection structure of a solder paste in which solder particles as conductive particles are densely filled. This can also be considered in the case where the conductive particles are solder particles, but it is not limited to this in the case where the conductive particles are compressed and flattened conductive particles such as metal-coated resin core particles. Explanation of reference numerals

[0060] 1 Connection structure 2 Connection material (conductive particle-containing layer) formed of a film-like adhesive material and conductive particles 2' Connection material derived from the conductive particle-containing layer after thermocompression bonding 3 Conductive particles 3' Portion derived from the conductive particles 4 Adhesive material (adhesive material layer) 4' Portion derived from the adhesive material Region where there is no connection material before thermocompression bonding Region where there is no connection material in the connection structure after thermocompression bonding 10 Electronic component, μLED 11 Electrode 11a, 11b Adjacent electrodes within the electronic component 20 Substrate 21 Electrode 21a, 21b Adjacent electrodes within the electronic component d Minimum width of the region where there is no connection material before thermocompression bonding d' Minimum width of the region where there is no connection material in the connection structure after thermocompression bonding

Claims

1. A connection structure that connects the electrodes of opposing electronic components and the electrodes of a substrate with a connection material derived from a conductive particle-containing layer in which conductive particles are held in an adhesive material. When viewed from above the connection surface between the electrodes of the electronic component and the electrodes of the substrate, there is a region where the connection material derived from the conductive particle-containing layer does not exist between adjacent electrodes within the electronic component.

2. The connection structure according to claim 1, wherein, The connection structure has a plurality of electronic components that connect the electrodes of the electronic components and the electrodes of the substrate with a connection material derived from a conductive particle-containing layer. In more than 90% of all the electronic components, there is a region where the connection material derived from the conductive particle-containing layer does not exist between adjacent electrodes within the electronic component.

3. The connecting structure according to claim 1 or 2, wherein The connection material derived from the conductive particle-containing layer is a connection material of a conductive particle-containing film in which conductive particles are held in a film-like adhesive material.

4. A method for manufacturing a connection structure, which is a method for manufacturing the connection structure according to claim 1. A conductive particle-containing layer in which conductive particles are held in an adhesive material is formed on the electrodes of the electronic component or the electrodes of the substrate, and a region where the conductive particle-containing layer does not exist is formed between adjacent electrodes within the electronic component or between the corresponding electrodes of the substrate. The conductive particle-containing layer is sandwiched between the electrodes of the electronic component and the electrodes of the substrate, and connection is performed by at least heating or pressurizing.

5. The manufacturing method of the connection structure according to claim 4, wherein The conductive particle-containing layer does not contain a curable resin.

6. The manufacturing method according to claim 4 or 5, wherein, The content ratio of the conductive particles in the conductive particle-containing layer is 20% by volume or more and 60% by volume or less.

7. The manufacturing method according to claim 4 or 5, wherein The area occupancy ratio of the conductive particles in the conductive particle-containing layer on the electrodes of the electronic component to the area of the electrodes is greater than 35%.

8. The manufacturing method according to claim 4 or 5, wherein The manufactured connection structure has a plurality of electronic components. In more than 60% of all the electronic components, the minimum width of the region where the conductive particle-containing layer does not exist exceeds 2 μm.

9. The manufacturing method according to claim 4 or 5, wherein The conductive particle-containing layer is a conductive particle-containing film.

10. A conductive particle-containing film used in the method for manufacturing the connection structure according to claim 4, which holds conductive particles in a film-like adhesive material.

11. The conductive particle-containing film according to claim 10, wherein, The content ratio of the conductive particles is 20 to 60% by volume.

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