Connection structure and method for manufacturing a connection structure

Abstract

The present invention provides a connection structure comprising: a first circuit component having a plurality of first electrodes; a second circuit component having a plurality of second electrodes; and an intermediate layer having a plurality of junctions electrically connecting the first electrodes and the second electrodes, wherein at least one of the first electrodes and the second electrodes connected by the junctions is a gold electrode, and more than 90% of the plurality of junctions include: a first region connecting the first electrodes and the second electrodes and containing a tin-gold alloy; and a second region in contact with the first region and containing bismuth.

Description

Technical Field

[0001] This invention relates to a connecting structure and a method for manufacturing the connecting structure. Background Technology

[0002] After semiconductor chips mounted on electronic devices are attached to a circuit board via wire bonding or ball grid array (BGA) connections using solder balls, they are sealed with an insulating resin material and used as a functional assembly called a semiconductor package. In particular, BGA connections contribute to the miniaturization of semiconductor packages because they can reduce the spacing between electrodes (Patent Document 1).

[0003] In recent years, for small and high-functionality products such as smartphones or tablets, there has been a push for miniaturization, thinning, and increased functionality in semiconductor packaging. As the number of connected electrodes increases, the spacing between the electrodes becomes narrower. On the primary connection side of a semiconductor package, a solder-coated Cu pillar structure with solder layered on the front end of the copper pillar is used to achieve narrow-pitch connections of less than 100 μm (Patent Document 2).

[0004] Furthermore, from an environmental performance perspective, since the 2000s, lead-free solder with added silver or copper in tin has been used, and assembly is performed using reflow temperatures around 260°C. However, in semiconductor packages, which are composites of metal, glass, and resin, there is a problem that the thermal history caused by reflow at 260°C leads to different thermal expansion rates of the materials, resulting in stress on the mounting portion (soldering part) and causing damage. Additionally, during reflow at 260°C, there is also the problem of alloying between the solder and the electrode metal, leading to the formation of an alloy layer that promotes damage. Furthermore, since tin-silver system solders require reflow at 260°C, there is a problem that cheaper resin materials cannot be used. Patent Document 3 discloses an assembly method using low-temperature solder, which uses tin and bismuth and has a melting point below 200°C. However, tin-bismuth solder has the following problem: because bismuth is brittle, the solder joint is easily damaged by external impacts. In Patent Document 4, an attempt was made to improve the brittleness of the joint by adding a trace amount of metal to the tin-bismuth solder.

[0005] On the other hand, as a method for electrically connecting multiple electrodes together, anisotropic conductive materials such as anisotropic conductive films and anisotropic conductive pastes have been conventionally used. Anisotropic conductive materials are used for mounting multiple wires together, such as for mounting control ICs in displays and connecting / installing indicator lines. In recent years, narrow-pitch connections of less than 30 μm have become possible. As conductive particles that work in conjunction with these anisotropic conductive materials, the use of solder particles has been studied in the past. For example, Patent Document 5 describes a conductive paste that contains a thermosetting component and multiple solder particles that have undergone specific surface treatment.

[0006] Previous technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Publication No. 2003-7894

[0009] Patent Document 2: Japanese Patent Publication No. 2015-106654

[0010] Patent Document 3: Japanese Patent Publication No. 2014-84395

[0011] Patent Document 4: WO2014061085

[0012] Patent Document 5: Japanese Patent Publication No. 2016-76494 Summary of the Invention

[0013] The technical problem to be solved by the invention

[0014] Thus, in recent years, the ongoing efforts to reduce connection temperatures in response to the diversification of circuit components, along with the miniaturization and thinning of highly refined connection parts of circuit components, have made it difficult to ensure the conductivity reliability of connection structures.

[0015] The present invention was made in view of the above circumstances, and its purpose is to provide a connection structure with excellent conduction reliability and insulation reliability, and a method for manufacturing the same.

[0016] means for solving technical problems

[0017] One aspect of the present invention relates to a connection structure comprising: a first circuit component having a plurality of first electrodes; a second circuit component having a plurality of second electrodes; and an intermediate layer having a plurality of junctions electrically connecting the first electrodes and the second electrodes, wherein at least one of the first electrodes and the second electrodes connected by the junctions is a gold electrode, and more than 90% of the plurality of junctions include: a first region connecting the first electrodes and the second electrodes and containing a tin-gold alloy; and a second region in contact with the first region and containing bismuth.

[0018] In one embodiment, the intermediate layer may also have an insulating resin layer that seals the space between the first circuit component and the second circuit component.

[0019] Another aspect of the present invention relates to a method for manufacturing a connecting structure, comprising: a preparation step of preparing a first circuit component having a plurality of first electrodes, a second circuit component having a plurality of second electrodes, and an anisotropic conductive film; an arrangement step of arranging the first circuit component, the second circuit component, and the anisotropic conductive film such that the surface of the first circuit component having the first electrode and the surface of the second circuit component having the second electrode are facing each other across the anisotropic conductive film, thereby obtaining a laminate in which the first circuit component, the anisotropic conductive film, and the second circuit component are sequentially stacked; and a connection step of heating the laminate while pressing it along its thickness direction, thereby electrically connecting the first electrode and the second electrode via a joint. In this manufacturing method, at least one of the first electrode and the second electrode is a gold electrode, and the anisotropic conductive film comprises an insulating film composed of an insulating resin composition and a plurality of solder particles disposed in the insulating film. Furthermore, the solder particles contain a tin-bismuth alloy, the average particle size of the solder particles is 1 μm to 30 μm, and the CV value of the solder particles is 20% or less. Furthermore, in the longitudinal section of the anisotropic conductive film, the solder particles are arranged laterally in a state of separation from adjacent solder particles. Moreover, more than 90% of the plurality of joints formed in the bonding process include: a first region connecting the first electrode and the second electrode and containing a tin-gold alloy; and a second region in contact with the first region and containing bismuth.

[0020] In one embodiment, the solder particles can be solder particles manufactured by a method comprising: a solder particle preparation step of preparing a substrate having a plurality of recesses and solder particles containing a tin-bismuth alloy; a receiving step of receiving at least a portion of the solder particles in the recesses; and a fusion step of fusing the solder particles received in the recesses to form solder particles inside the recesses.

[0021] In one approach, the CV value of the solder particles prepared in the solder particle preparation step can exceed 20.

[0022] In one embodiment, the anisotropic conductive film can be an anisotropic conductive film manufactured by a method comprising: a transfer step in which an insulating resin composition is contacted with the opening side of a recess of a substrate having a plurality of recesses containing solder particles to obtain a first resin layer transferred with solder particles; and a lamination step in which a second resin layer composed of an insulating resin composition is formed on the surface of the first resin layer on the side where the solder particles are transferred, thereby obtaining the anisotropic conductive film.

[0023] Invention Effects

[0024] According to the present invention, a connection structure with excellent conductivity and insulation reliability and a method for manufacturing the same are provided. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view schematically illustrating a first embodiment of anisotropic conductive film.

[0026] Figure 2 (a) is Figure 1 A schematic cross-sectional view along line IIa-IIa shown. Figure 2 (b) A cross-sectional view schematically showing a variation of the first embodiment.

[0027] Figure 3 (a) A top view schematically representing an example of a substrate. Figure 3 (b) is Figure 3 (a) is a cross-sectional view along line Ib-Ib.

[0028] Figure 4 (a) to (h) are sectional views illustrating examples of the cross-sectional shape of the recessed portion of the substrate.

[0029] Figure 5 A cross-sectional view schematically showing the state in which solder particles are contained in the recess of the substrate.

[0030] Figure 6 A cross-sectional view schematically showing the state in which solder particles are formed in the recess of the substrate.

[0031] Figure 7 (a) is from and Figure 6 A diagram showing solder particles observed on the side opposite to the opening of the concave portion. Figure 7 (b) is a graph showing the distances X and Y (where Y ≤ X) between opposite sides when a quadrilateral circumscribed to the projected image of solder particles is made by two pairs of parallel lines.

[0032] Figure 8 (a) to (c) are cross-sectional views schematically illustrating an example of the manufacturing process of the anisotropic conductive film of the first embodiment.

[0033] Figure 9 (a) to (c) are cross-sectional views schematically illustrating an example of the manufacturing process of the anisotropic conductive film of the second embodiment.

[0034] Figure 10 (a) and Figure 10 (b) A cross-sectional view illustrating another example of the manufacturing process of anisotropic conductive films.

[0035] Figure 11 The diagram is an enlarged view showing a portion of the connecting structure, and a cross-sectional view schematically showing the state in which the first electrode and the second electrode are electrically connected through the joint.

[0036] Figure 12 (a) and Figure 12 (b) A cross-sectional view schematically illustrating a first example of the manufacturing process of the connection structure of the present invention.

[0037] Figure 13 (a) and Figure 13 (b) A cross-sectional view illustrating a second example of the manufacturing process of the connection structure of the present invention.

[0038] Figure 14 (a) and Figure 14 (b) A cross-sectional view illustrating a third example of the manufacturing process of the connection structure of the present invention.

[0039] Figure 15 (a) Figure 15 (b) Figure 15 (c) and Figure 15 (d) is a cross-sectional view schematically showing an example of the junction including the first region and the second region.

[0040] Figure 16 (a) Figure 16 (b) Figure 16 (c) and Figure 16 (d) are cross-sectional views schematically showing an example of the junction including the first region and the second region.

[0041] Figure 17 (a) Figure 17 (b) Figure 17 (c) Figure 17 (d) Figure 17 (e) and Figure 17 (f) are top views that schematically show an example of the junction including the first region and the second region.

[0042] Figure 18 (a) Figure 18 (b) and Figure 18 (c) are cross-sectional views schematically showing an example of the junction excluding the first region and the second region.

[0043] Figure 19 (a) Figure 19 (b) Figure 19 (c) and Figure 19 (d) are cross-sectional views schematically showing an example of the junction excluding the first and second regions.

[0044] Figure 20 A top view illustrating, schematically, the relationship between the positions of solder particles and bumps (electrodes) on an anisotropic conductive film before it is pressed and heated.

[0045] Figure 21 A top view illustrating a second example of the relationship between the position of solder particles and the position of bumps (electrodes) in an anisotropic conductive film before it is pressed and heated.

[0046] Figure 22 A top view illustrating the relationship between the positions of solder particles and bumps (electrodes) on an anisotropic conductive film before it is pressed and heated.

[0047] Figure 23 A top view illustrating the relationship between the position of solder particles and bumps (electrodes) on an anisotropic conductive film before it is pressed and heated.

[0048] Figure 24 A cross-sectional view illustrating another example of the cross-sectional shape of a recess in a substrate.

[0049] Figure 25 (a) is a cross-sectional view of the connecting structure after it has been pressed and heated. Figure 25 (b) is a graph showing the EDX analysis results of the cross-sectional image. Detailed Implementation

[0050] The embodiments of the present invention will be described below. The present invention is not limited to the following embodiments. Furthermore, unless otherwise stated, the materials exemplified below may be used alone or in combination of two or more. In the case where multiple substances equivalent to each component are present in the composition, unless otherwise stated, the content of each component in the composition refers to the total amount of the multiple substances present in the composition. The numerical range indicated by "~" represents the range including the minimum and maximum values, respectively, of the values ​​before and after "~". In the numerical ranges described in stages in this specification, the upper or lower limit of the numerical range for one stage may be replaced by the upper or lower limit of the numerical range for another stage. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced by the values ​​shown in the examples.

[0051] The connection structure of this embodiment includes: a first circuit component having a plurality of first electrodes; a second circuit component having a plurality of second electrodes; and an intermediate layer having a plurality of junctions electrically connecting the first electrodes and the second electrodes. Furthermore, at least one of the first electrodes and the second electrodes connected by the junctions is a gold electrode, and more than 90% of the plurality of junctions include: a first region connecting the first electrodes and the second electrodes and containing a tin-gold alloy; and a second region in contact with the first region and containing bismuth.

[0052] The connection structure of this embodiment includes a joint portion comprising: a first region connecting a first electrode and a second electrode; and a second region contacting the first region. In this joint portion, since the first region is integrally formed with a tin-gold alloy, and the second region functions as a reinforcement, cracking is less likely to occur. Furthermore, since the first region contains a high-melting-point tin-gold alloy, remelting of the joint is effectively suppressed. In the connection structure of this embodiment, more than 90% of the joint comprises both the first and second regions, thus effectively suppressing cracking and melting in the joint, and providing excellent conductivity reliability. Moreover, because the melting of the joint is effectively suppressed in this connection structure, it is easily adaptable for secondary installations and is also suitable for use in high-temperature environments.

[0053] The intermediate layer may also have an insulating resin layer that seals the space between the first circuit component and the second circuit component. The insulating resin layer may be formed of an insulating film made of anisotropic conductive film, as described later.

[0054] In this embodiment, the proportion of the joint portion including the first region and the second region in the joint portion of the connecting structure is 80% or more, preferably 85% or more, more preferably 90% or more, and may also be 100%.

[0055] In order to make most of the joints of the connection structure include both a first region and a second region, it is desirable that the solder particles used to form each joint be uniform. Furthermore, in order to make most of the joints of the connection structure include both the first and second regions, an insulating resin composition is disposed around the solder particles, and when the solder particles melt, it is desirable that the molten solder remains between the first and second electrodes for a sufficient time. From these viewpoints, it is preferable that the connection structure of this embodiment uses an anisotropic conductive film as shown below to join the first circuit component and the second circuit component.

[0056] Hereinafter, with reference to the accompanying drawings, we will describe the anisotropic conductive film useful in manufacturing the connection structure, the method of manufacturing the same, and a preferred embodiment of the connection structure and the method of manufacturing the same.

[0057] <Anisotropic Conductive Film>

[0058] Figure 1 The anisotropic conductive film 10 of the first embodiment shown is composed of an insulating film 2 made of an insulating resin composition and a plurality of solder particles 1 disposed in the insulating film 2. In a predetermined longitudinal section of the anisotropic conductive film 10, a solder particle 1 is configured to be separated from an adjacent solder particle 1 along the transverse direction (…). Figure 1The anisotropic conductive film 10 is arranged in the left-right direction. In other words, the anisotropic conductive film 10 is composed of a central region 10a formed by multiple solder particles 1 in the transverse direction in its longitudinal section and surface side regions 10b and 10c where there are no solder particles 1.

[0059] Figure 2 (a) is Figure 1 A schematic cross-sectional view along line IIa-IIa shown. (See attached image.) Figure 2 As shown, solder particles 1 are regularly arranged on the cross-section of the anisotropic conductive film 10. Figure 2 As shown in (a), solder particles 1 can be regularly and at approximately uniform intervals distributed throughout the anisotropic conductive film 10, such as... Figure 2 In the modified example shown in (b), the solder particles 1 can also be arranged in a regular manner on the cross-section of the anisotropic conductive film 10, forming a region 10d in which a plurality of solder particles 1 are regularly arranged and a region 10e in which there are no solder particles 1 in substance. For example, the position and number of solder particles 1 can be set according to the shape, size and pattern of the electrode to be connected.

[0060] (Solder particles)

[0061] The average particle size of the solder particles 1 is, for example, 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. Furthermore, the average particle size of the solder particles 1 is, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0062] The average particle size of solder particles 1 can be determined using various methods that match the size. For example, methods such as dynamic light scattering, laser diffraction, centrifugal sedimentation, electrical detection band method, and resonant mass determination can be used. Furthermore, methods can be employed to determine particle size from images obtained using optical microscopes, electron microscopes, etc. Specific devices include flow particle image analysis devices, Macchick particle size analyzers, and Coulter counters.

[0063] From the viewpoint of achieving superior conductivity and insulation reliability, the CV value of solder particles 1 is preferably 20% or less, more preferably 10% or less, and even more preferably 7% or less. Furthermore, the lower limit of the CV value of solder particles 1 is not particularly limited. For example, the CV value of solder particles 1 can be 1% or more, or 2% or more.

[0064] The CV value of solder particle 1 is calculated by multiplying 100 by the value obtained by dividing the standard deviation of the particle size determined by the method by the average particle size.

[0065] like Figure 7As shown in (a), the solder particle 1 may have a planar portion 11 formed on a portion of its surface, and the surface other than the planar portion 11 is preferably spherical. That is, the solder particle 1 may have a planar portion 11 and a spherical crown-shaped curved surface. The ratio (A / B) of the diameter A of the planar portion 11 to the diameter B of the solder particle 1 may, for example, exceed 0.01 and be less than 1.0 (0.01 < A / B < 1.0), or it may be 0.1 to 0.9. Since the solder particle 1 has a planar portion 11, displacement caused by pressure is less likely to occur during connection, and superior conductivity and insulation reliability can be achieved.

[0066] When a quadrilateral circumscribed to the projected image of solder particle 1 is created by two pairs of parallel lines, and the distance between the opposing sides is set as X and Y (where Y < X), the ratio of Y to X (Y / X) can be greater than 0.8 and less than 1.0 (0.8 < Y / X < 1.0), or greater than 0.9 and less than 1.0. This solder particle 1 can be described as a particle that is closer to a sphere. According to the manufacturing method described later, this solder particle 1 can be easily obtained. Since the solder particle 1 is close to a sphere, for example, when multiple opposing electrodes are electrically connected via the solder particle 1, it tends to be less prone to unevenness in the contact between the solder particle 1 and the electrodes, and a stable connection can be obtained. Furthermore, when a conductive film or resin in which the solder particle 1 is dispersed in a resin composition is manufactured, high dispersibility and dispersion stability during manufacturing are tended to be obtained. Furthermore, when a film or paste in which solder particles 1 are dispersed in a resin composition is used to connect electrodes, even if the solder particles 1 rotate in the resin, if the solder particles 1 are spherical, their projected areas are similar when observed in a projection image. Therefore, there tends to be less deviation when connecting electrodes, and a stable electrical connection is easily obtained.

[0067] Figure 7 (b) A graph showing the distances X and Y (where Y < X) between opposite sides when a quadrilateral circumscribed by a projection image of a solder particle is created from two pairs of parallel lines. For example, a projection image is obtained by observing an arbitrary particle using a scanning electron microscope. Two pairs of parallel lines are plotted on the obtained projection image, one pair positioned at the point of minimum distance between parallel lines and the other pair positioned at the point of maximum distance between parallel lines, and the Y / X of the particle is calculated. This operation is performed on 300 solder particles, and the average value is calculated and set as the Y / X of the solder particle.

[0068] Solder particle 1 contains a tin-bismuth alloy (Sn-Bi alloy). Specific examples of tin-bismuth alloys can be given below.

[0069] • Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138℃)

[0070] • Sn-Bi (Sn 72% by mass, Bi 28% by mass, melting point 138℃)

[0071] • Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139℃)

[0072] The solder particles 1 may also contain metals other than Sn and Bi. Examples of other metals include Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, B, Ga, As, Sb, Te, Ge, Si, and Al. The content of other metals in the solder particles 1 is, for example, 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less.

[0073] (Insulating film)

[0074] The insulating resin composition constituting the insulating film 2 may include a thermosetting compound. Examples of thermosetting compounds include oxobutane compounds, epoxy compounds, cyclic sulfide compounds, (meth)acrylic acid compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. Among these, from the viewpoint of further optimizing the curability and viscosity of the insulating resin and further improving the connection reliability, an epoxy compound is preferred.

[0075] The insulating resin composition may also include a thermosetting agent. Examples of thermosetting agents include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, acid anhydrides, thermal cationic initiators, and thermal free radical generators. These can be used individually or in combination of two or more. From the viewpoint of rapid curing at low temperatures, imidazole curing agents, polythiol curing agents, or amine curing agents are preferred. Furthermore, when a thermosetting compound is mixed with a thermosetting agent, storage stability is improved; therefore, a latent curing agent is preferred. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent, or a latent amine curing agent. Additionally, the aforementioned thermosetting agents can be coated with polymers such as polyurethane resins or urethane resins.

[0076] The imidazole curing agent is not particularly limited to the above-mentioned imidazoles, and examples include 2-methylimidazolium, 2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 1-cyanoethyl-2-phenylimidazolium trimer, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adducts, etc.

[0077] The polythiol curing agent is not particularly limited, and examples include trimethylolpropane tri-3-mercaptopropionate, neopentyl tetroxide tetra-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. The solubility parameter of the polythiol curing agent is preferably 9.5 or higher, and more preferably 12 or lower. The solubility parameter is calculated using the Fedors method. For example, the solubility parameter of trimethylolpropane tri-3-mercaptopropionate is 9.6, and the solubility parameter of dipentaerythritol hexa-3-mercaptopropionate is 11.4.

[0078] The above-mentioned amine curing agents are not particularly limited, and examples include hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro[5.5]undecane, bis(4-aminocyclohexyl)methane, methylphenyldiamine, and diaminodiaminodiphenyl sulfone, etc.

[0079] Examples of the aforementioned cationic curing agents include iodonium-based cationic curing agents, oxonium-based cationic curing agents, and sulfonium-based cationic curing agents. Examples of iodonium-based cationic curing agents include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of oxonium-based cationic curing agents include trimethyloxonium tetrafluoroboric acid. Examples of sulfonium-based cationic curing agents include tri-p-tolylsulfonium hexafluorophosphate.

[0080] The above-mentioned thermal free radical generators are not particularly limited, and examples include azo compounds and organic peroxides. Examples of azo compounds include azobisisobutyronitrile (AIBN). Examples of organic peroxides include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

[0081] (Fluid)

[0082] The anisotropic conductive film 10 preferably contains a flux. Specifically, the insulating resin composition constituting the anisotropic conductive film 10 preferably contains a flux, and the flux covers the surface of the solder particles 1. The flux melts the oxides on the solder surface to improve the weldability of the solder particles to each other and the wettability of the solder to the electrode.

[0083] As a flux, it can be used in common applications such as soldering. Specific examples include zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, derivatives of phosphoric acid, organohalides, hydrazine, organic acids, and rosin. These can be used alone or in combination with two or more.

[0084] Examples of molten salts include ammonium chloride. Examples of organic acids include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of rosin include activated and unactivated rosin. Rosin is a type of rosin with pinoresinic acid as its main component. Using organic acids or rosin with two or more carboxyl groups as fluxes further improves the reliability of conductivity between electrodes.

[0085] The melting point of the flux is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. The melting point of the flux is preferably 200°C or lower, more preferably 160°C or lower, even more preferably 150°C or lower, and particularly preferably 140°C or lower. If the melting point of the flux is above the lower limit and below the upper limit, the fluxing effect is further enhanced, and the solder particles are more effectively disposed on the electrode. The melting point range of the flux is preferably 80–190°C, more preferably 80–140°C or lower.

[0086] Examples of fluxes with melting points in the range of 80 to 190°C include succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), octanoic acid (melting point 142°C), dicarboxylic acids, benzoic acid (melting point 122°C), and malic acid (melting point 130°C).

[0087] <Method for Manufacturing Anisotropic Conductive Films>

[0088] The method for manufacturing anisotropic conductive film 10 includes: a solder particle preparation step, in which a substrate having a plurality of recesses and solder particles are prepared; a receiving step, in which at least a portion of the solder particles are received in the recesses; a fusion step, in which the solder particles received in the recesses are fused together to form solder particles inside the recesses; a transfer step, in which an insulating resin composition is brought into contact with the opening side of the recesses of the substrate in which the solder particles are received, to obtain a first resin layer with solder particles transferred thereon; and a lamination step, in which a second resin layer composed of an insulating resin composition is formed on the surface of the first resin layer on the side with solder particles transferred thereon, thereby obtaining an anisotropic conductive film.

[0089] refer to Figures 3-8 The manufacturing method of the anisotropic conductive film 10 of the first embodiment will be described.

[0090] First, prepare solder particles and a substrate 60 for holding the solder particles. Figure 3 (a) A top view schematically showing an example of the base 60. Figure 3 (b) is Figure 3 (a) is a cross-sectional view along line Ib-Ib shown. Figure 3(a) The substrate 60 shown has a plurality of recesses 62. The plurality of recesses 62 can be arranged regularly in a predetermined pattern. In this case, the substrate 60 can be used directly in the transfer process described later.

[0091] The recess 62 of the substrate 60 is preferably formed in a conical shape, wherein the opening area of ​​the cone increases from the bottom 62a side of the recess 62 toward the surface 60a side of the substrate 60. That is, as Figure 3 (a) and Figure 3 As shown in (b), the width of the bottom 62a of the recess 62 ( Figure 3 (a) and Figure 3 (b) The width of (a) is preferably greater than the opening width in the surface 60a of the recess 62. Figure 3 (a) and Figure 3 (b) has a narrow width. Moreover, the dimensions of the recess 62 (width a, width b, volume, cone angle, and depth, etc.) can be set according to the target size of the solder particles.

[0092] In addition, the shape of the recess 62 can be, except for Figure 3 (a) and Figure 3 Shapes other than those shown in (b). For example, besides those shown in (b). Figure 3 In addition to the circle shown in (a), the shape of the opening in the surface 60a of the recess 62 can also be elliptical, triangular, quadrilateral, polygonal, etc.

[0093] Furthermore, the shape of the recess 62 in the cross-section perpendicular to surface 60a can be, for example, as follows: Figure 4 The shape shown. Figure 4 (a) to (h) are sectional views schematically illustrating examples of the cross-sectional shape of a recess in a substrate. Figure 4 In any of the cross-sectional shapes shown in (a) to (h), the width (width b) of the opening in the surface 60a of the recess 62 is the maximum width in the cross-sectional shape. This facilitates the removal of solder particles formed within the recess 62 and improves operability. Furthermore, for example, as... Figure 24 As shown, the shape of the recess 62 in the cross-section perpendicular to surface 60a can be... Figure 4 The shape of the inclined wall in the cross-sectional shapes shown in (a) to (h). Figure 24 Can be called making Figure 4 (b) shows the shape of the inclined wall in the cross-section.

[0094] The substrate 60 can be made of inorganic materials such as silicon, various ceramics, glass, and stainless steel, as well as organic materials such as various resins. Preferably, the substrate 60 is composed of a heat-resistant material that does not deteriorate at the melting temperature of the solder particles. Furthermore, the recesses 62 of the substrate 60 can be formed using known methods such as photolithography, imprinting, and etching.

[0095] The solder particles prepared in the solder particle preparation process may include particles with a diameter smaller than the width (width b) of the opening in the surface 60a of the recess 62, and preferably include more particles with a diameter smaller than the width b. For example, in the solder particles, it is preferable that the D10 particle size distribution is smaller than the width b, more preferably that the D30 particle size distribution is smaller than the width b, and even more preferably that the D50 particle size distribution is smaller than the width b.

[0096] The particle size distribution of solder particles can be determined using various methods tailored to their size. For example, methods such as dynamic light scattering, laser diffraction, centrifugal sedimentation, electrical detection band analysis, and resonant mass determination can be employed. Furthermore, methods can be used to determine particle size from images obtained through optical microscopes, electron microscopes, etc. Specific devices include flow particle image analysis devices, Microtrac particle size analyzers, and Coulter counters.

[0097] The CV value of the solder particles prepared in the preparation process is not particularly limited, but from the viewpoint of improving the filling performance of the recess 62 by combining large and small particles, a high CV value is preferred. For example, the CV value of the solder particles can exceed 20%, preferably 25% or more, and more preferably 30% or more.

[0098] The CV value of solder particles is calculated by multiplying 100 by the value obtained by dividing the standard deviation of the particle size determined by the method by the average particle size (D50 particle size).

[0099] Solder particles contain tin-bismuth alloys (Sn-Bi alloys). Specific examples of tin-bismuth alloys can be given below.

[0100] • Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138℃)

[0101] • Sn-Bi (Sn 72% by mass, Bi 28% by mass, melting point 138℃)

[0102] • Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139℃)

[0103] The solder particles may also contain metals other than Sn and Bi. Examples of such metals include Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, B, Ga, As, Sb, Te, Ge, Si, and Al. The content of other metals in the solder particles is, for example, 10% by mass or less, preferably 5% by mass or less, and more preferably 3% by mass or less.

[0104] In the receiving process, solder particles prepared in the solder particle preparation process are received in each recess 62 of the substrate 60. The receiving process can be a process that receives all the solder particles prepared in the solder particle preparation process in the recess 62, or it can be a process that receives a portion of the solder particles prepared in the solder particle preparation process (e.g., in the solder particles that is smaller than the width b of the opening of the recess 62) in the recess 62.

[0105] Figure 5 A cross-sectional view schematically showing the state in which solder particles 111 are contained in the recess 62 of the substrate 60. (See attached image.) Figure 5 As shown, each of the plurality of recesses 62 contains a plurality of solder particles 111.

[0106] The amount of solder particles 111 contained in the recess 62 is preferably 20% or more, more preferably 30% or more, further preferably 50% or more, and most preferably 60% or more, relative to the volume of the recess 62. This suppresses deviations in the amount contained and facilitates the production of solder particles with a smaller particle size distribution.

[0107] The method of collecting solder particles in the recess 62 is not particularly limited. The collection method can be either dry or wet. For example, solder particles prepared in the preparation process can be placed on the substrate 60, and the surface 60a of the substrate 60 can be wiped with a scraper. This removes excess solder particles while collecting sufficient solder particles in the recess 62. When the width b of the opening of the recess 62 is greater than the depth of the recess 62, solder particles may sometimes pop out from the opening of the recess 62. If a scraper is used, the solder particles that pop out from the opening of the recess 62 are removed. As a method for removing excess solder particles, methods such as wiping the surface 60a of the substrate 60 with compressed air or a non-woven fabric or fiber bundle can also be cited. Compared to a scraper, these methods are preferred in handling easily deformable solder particles due to the weaker physical force. Furthermore, in these methods, solder particles that pop out from the opening of the recess 62 can also remain inside the recess.

[0108] The fusion process is a process of fusing the solder particles 111 contained in the recess 62 to form solder particles 1 inside the recess 62. Figure 6 This is a cross-sectional view schematically showing the state in which solder particles 1 are formed in the recess 62 of the substrate 60. The solder particles 111 contained in the recess 62 are unified by melting and spherical by surface tension. At this time, in the contact portion with the bottom 62a of the recess 62, the molten solder follows the bottom 62a to form a planar portion 11. Thus, the formed solder particles 1 have a shape with a planar portion 11 on a part of their surface.

[0109] Figure 7 (a) is from Figure 6 The diagram shows the solder particle 1 viewed from the opposite side of the opening of the recess 62. The solder particle 1 has a shape in which a planar portion 11 of diameter A is formed on a part of the surface of a sphere having diameter B. Furthermore, since the bottom 62a of the recess 62 is planar, therefore... Figure 6 and Figure 7 (a) The solder particle 1 shown has a planar portion 11, but when the bottom 62a of the recess 62 is a shape other than a planar shape, it has a surface with a different shape corresponding to the shape of the bottom 62a.

[0110] One method for melting the solder particles 111 housed in the recess 62 is to heat the solder particles 111 to a temperature above the melting point of solder. Due to the influence of the oxide film, even when heated to a temperature above the melting point, the solder particles 111 sometimes fail to melt, sometimes fail to wet and diffuse, and sometimes fail to coalesce. Therefore, by exposing the solder particles 111 to a reducing environment, removing the surface oxide film, and then heating them to a temperature above the melting point of the solder particles 111, it is possible to melt, wet, diffuse, and coalesce the solder particles 111. Furthermore, the melting of the solder particles 111 is preferably performed in a reducing environment. By heating the solder particles 111 to a temperature above their melting point and setting the environment to a reducing state, the oxide film on the surface of the solder particles 111 is reduced, making it easy and effective to melt, wet, diffuse, and coalesce the solder particles 111.

[0111] There are no particular limitations on the method of creating a reducing environment, as long as it achieves the aforementioned effects. For example, methods using hydrogen gas, hydrogen radicals, or formic acid gas can be employed. For instance, by using a hydrogen reduction furnace, a hydrogen radical reduction furnace, a formic acid reduction furnace, or these conveyor-type or continuous furnaces, solder particles 111 can be melted in a reducing environment. These devices can include a heating device, a chamber filled with an inert gas (nitrogen, argon, etc.), and a mechanism for maintaining a vacuum within the chamber, thereby making it easier to control the reducing gas. Furthermore, if the chamber can be kept under vacuum, after the solder particles 111 melt and coalesce, porosity can be removed by depressurization, resulting in solder particles 1 with superior bonding stability.

[0112] The reduction and dissolution conditions, temperature, and furnace environment adjustments for solder particles 111 can be appropriately set considering the melting point, particle size, recess size, and substrate material 60 of the solder particles 111. For example, the substrate 60, into which the solder particles 111 are filled, is inserted into the furnace. After evacuation, reducing gas is introduced and the furnace is filled with reducing gas. After removing the surface oxide film of the solder particles 111, the reducing gas is removed by evacuation. Then, the temperature is heated above the melting point of the solder particles 111 to dissolve and unify the solder particles. After forming solder particles in the recess 62, nitrogen is filled, and then the furnace temperature is restored to room temperature to obtain solder particles 1. Furthermore, for example, a substrate 60 filled with solder particles 111 in a recess is inserted into a furnace. After evacuation, a reducing gas is introduced and the furnace is filled with the reducing gas. The solder particles 111 are heated by a furnace heater to remove the surface oxide film of the solder particles 111. The reducing gas is then removed by evacuation, and the temperature is then raised above the melting point of the solder particles 111 to dissolve and unify the solder particles. Solder particles are formed in the recess 62, and nitrogen is then added. The furnace temperature is then restored to room temperature, thus obtaining solder particles 1. By heating the solder particles in a reducing environment, the reducing power is increased, which has the advantage of easily removing the surface oxide film of the solder particles.

[0113] Furthermore, for example, a substrate 60 filled with solder particles 111 in a recess is inserted into a furnace. After evacuation, a reducing gas is introduced and the furnace is filled with the reducing gas. The substrate 60 is heated by a furnace heater to a temperature above the melting point of the solder particles 111. The surface oxide film of the solder particles 111 is removed by reduction, while the solder particles are dissolved and unified, thereby forming solder particles in the recess 62. The reducing gas is removed by evacuation. After reducing the porosity within the solder particles, nitrogen is filled, and then the furnace temperature is restored to room temperature, thus obtaining solder particles 1. In this case, the furnace temperature can be adjusted only once for both the rise and fall, thus having the advantage of being able to process in a short time.

[0114] An additional step can be added: after solder particles are formed in the aforementioned recess 62, the furnace interior is again set to a reducing environment to remove any remaining surface oxide film. This reduces residues such as unfused solder particles and a portion of the unfused oxide film.

[0115] In the case of using an atmospheric pressure conveyor belt furnace, a substrate 60 with solder particles 111 filled in a recess is placed on a conveyor belt, and solder particles 1 can be obtained by continuously passing it through multiple regions. For example, the substrate 60 with solder particles 111 filled in a recess is placed on a conveyor belt set to a constant speed, and it is passed through a region filled with an inert gas such as nitrogen or argon at a temperature lower than the melting point of the solder particles 111. Then, it is passed through a region where a reducing gas such as formic acid at a temperature lower than the melting point of the solder particles 111 is present to remove the surface oxide film of the solder particles 111. Then, it is passed through a region filled with an inert gas such as nitrogen or argon at a temperature above the melting point of the solder particles 111 to melt and unify the solder particles 111. Finally, it is passed through a cooling region filled with an inert gas such as nitrogen or argon, thereby obtaining solder particles 1. For example, a substrate 60 with solder particles 111 filled in the recesses is mounted on a conveyor belt set to a constant speed. It passes through an area filled with an inert gas such as nitrogen or argon at a temperature above the melting point of the solder particles 111. Next, it passes through an area containing a reducing gas such as formic acid at a temperature above the melting point of the solder particles 111 to remove the surface oxide film of the solder particles 111, melting and unifying them. Then, it passes through a cooling area filled with an inert gas such as nitrogen or argon, thereby obtaining solder particles 1. Since the conveyor belt furnace can process at atmospheric pressure, it can also continuously process film materials in a roll-to-roll manner. For example, to produce a continuous roll product of a substrate 60 with solder particles 111 filled in the recesses, an unwinding machine is installed at the inlet side of the conveyor belt furnace, and a winding machine is installed at the outlet side of the conveyor belt furnace. The substrate 60 is transported at a constant speed, and by passing it through various areas within the conveyor belt furnace, the solder particles 111 filled in the recesses can be fused together.

[0116] According to the solder particle preparation process and the fusion process, solder particles 1 of uniform size can be formed regardless of the material and shape of the solder particles 111. Furthermore, since the formed solder particles 1 can be processed while being housed in the recess 62 of the substrate 60, they can be handled and stored without deformation. In addition, because the formed solder particles 1 are simply housed in the recess 62 of the substrate 60, they are easy to remove, and can be recycled and surface-treated without deformation.

[0117] Furthermore, the solder particles 111 can have large deviations in particle size distribution and can also be deformed in shape. If they can be contained in the recess 62, they can be used as raw materials appropriately.

[0118] Furthermore, in the above method, the substrate 60 can freely design the shape of the recess 62 through photolithography, machining, imprinting, etching, etc. Since the size of the solder particles 1 depends on the amount of solder particles 111 contained in the recess 62, the size of the solder particles 1 can be freely designed by setting the recess 62.

[0119] The solder particles 1 formed in the fusion process can be used directly in the transfer process, or they can be used in the transfer process after being coated with flux components while still contained in the recess 62 of the substrate 60. Alternatively, they can be removed from the recess 62, coated with flux components, and then placed back into the recess 62 before being used in the transfer process. Furthermore, while the substrate 60 used to form the solder particles 1 can be used directly in the transfer process, in cases where a step includes removing the solder particles 1 from the recess 62, the removed solder particles 1 can also be placed in a substrate different from the substrate 60 and used in the transfer process.

[0120] The transfer process is as follows: the insulating resin material 2a is brought into contact with the substrate 60 in which the solder particles 1 are housed in the recess 62 from the opening side of the recess 62, thereby obtaining the first resin layer 2b on which the solder particles 1 are transferred.

[0121] Figure 8 (a) The substrate 60 shown is in a state where a solder particle 1 is received in each recess 62. The layered insulating resin composition 2a is positioned against the opening side surface of the recess 62 of the substrate 60, so that the substrate 60 is close to the layered insulating resin composition 2a. Figure 8 (Arrows A and B in (a)). Additionally, the layered insulating resin composition 2a is formed on the surface of the support 65. The support 65 can be a plastic film or a metal foil.

[0122] Figure 8 (b) The following state is shown: After the transfer process, the open side surface of the recess 62 of the substrate 60 is brought into contact with the layered insulating resin composition 2a, thereby transferring the solder particles 1 housed in the recess 62 of the substrate 60 onto the layered insulating resin composition 2a. Through the transfer process, a first resin layer 2b is obtained with a plurality of solder particles 1 transferred at predetermined positions on the layered insulating resin composition 2a. The first resin layer 2b exposes the plurality of solder particles 1 on its surface. Furthermore, in the above manufacturing method, the plurality of solder particles 1 are all arranged in the anisotropic conductive film 10 with the planar portion 11 facing the second resin layer 2d.

[0123] The lamination process is as follows: a second resin layer 2d composed of an insulating resin composition is formed on the surface 2c of the first resin layer 2b on the side where solder particles 1 are transferred, thereby obtaining an anisotropic conductive film 10.

[0124] Figure 8 (c) The following state is shown: After the lamination process, the support 65 is removed after the second resin layer 2d is formed on the surface 2c of the first resin layer 2b in such a way as to cover the solder particles 1. The second resin layer 2d can be formed by bonding an insulating film layer composed of an insulating resin composition to the first resin layer 2b, or it can be formed by performing a curing process after coating the first resin layer 2b with a varnish containing an insulating resin material.

[0125] Secondly, refer to Figure 9 The manufacturing method of the anisotropic conductive film 10 of the second embodiment will be described.

[0126] In the second embodiment, after the preparation, storage and fusion processes are performed in the same manner as in the first embodiment, the insulating resin composition is penetrated into the interior of the recess 62 in the transfer process, thereby embedding the solder particles 1 in the first resin layer 2b.

[0127] Figure 9 (a) The substrate 60 shown is in a state where a solder particle 1 is received in each recess 62. The layered insulating resin composition 2a is placed against the opening side surface of the recess 62 of the substrate 60, so that the substrate 60 is close to the layered insulating resin composition 2a. Figure 9 (arrows A and B in (a)).

[0128] Figure 9 (b) The following state is shown: In the state after the transfer process, the open side surface of the recess 62 of the substrate 60 is brought into contact with the layered insulating resin composition 2a, thereby transferring the solder particles 1 housed in the recess 62 of the substrate 60 onto the layered insulating resin composition 2a. Through the transfer process, a first resin layer 2b is obtained in which a plurality of solder particles 1 are disposed at predetermined positions. A plurality of protrusions 2e corresponding to the recess 62 are formed on the surface 2c side of the first resin layer 2b, and solder particles 1 are embedded in these protrusions 2e. To obtain this first resin layer 2b, the insulating resin material 2a is penetrated into the interior of the recess 62 during the transfer process. Specifically, by extending the substrate 60 and the layered insulating resin composition 2a along the lamination direction (… Figure 9 Applying pressure (in the directions of arrows A and B in (a)) allows the layered insulating resin composition 2a to penetrate into the interior of the recess 62. Furthermore, if the transfer process is performed under reduced pressure, the layered insulating resin composition 2a easily penetrates into the interior of the recess 62. And, in Figure 9 In this process, a transfer process is performed using a layered insulating resin material 2a. However, the first resin layer 2b can also be obtained by applying an insulating resin composition in the form of a varnish to the interior of the recess 62 and the surface of the substrate 60 and then performing a curing process.

[0129] Figure 9 (c) The following state is shown: After the lamination process, the support 65 is removed after the second resin layer 2d is formed on the surface 2c of the first resin layer 2b. The second resin layer 2d can be formed by laminating an insulating film composed of an insulating resin composition onto the first resin layer 2b, or by coating the first resin layer 2b with a varnish containing an insulating resin composition and then performing a curing process.

[0130] Furthermore, in the above manufacturing method, multiple solder particles 1 are disposed in the anisotropic conductive film 10 with their planar portions 11 facing the second resin layer 2d. In the case of repositioning the solder particles 1 formed in the fusion process into the recess 62 after taking them out and treating them with flux components, the orientation of the planar portions 11 of the multiple solder particles 1 can be different from each other. Figure 10 (a) shows the state in which the solder particles 1 that have been removed once are repositioned in the recess 62. By performing the transfer and lamination processes in this state, a plurality of solder particles 1 are arranged in the anisotropic conductive film 10 with inconsistent orientations of the planar portions 11. Figure 10 (b) is a diagram showing that multiple solder particles 1 are arranged in anisotropic conductive film 10 with inconsistent orientations of the planar portion 11.

[0131] <Connection Structure>

[0132] Figure 11 This is an enlarged view showing a portion of the connecting structure, and a cross-sectional view schematically showing the state in which the first electrode and the second electrode are electrically connected through the joint. That is, Figure 11 This illustration schematically shows the state in which the electrodes 32 of the first circuit component 30 and 42 of the second circuit component 40 are electrically connected via a joint 70 formed by the fusion of solder particles 1. As described above, in this specification, "fusion" refers to a state in which at least a portion of the electrodes are joined by solder particles 1 that melt due to heat, and then the solder is bonded to the electrode surface through a process of curing it. The first circuit component 30 includes a first circuit substrate 31 and a first electrode 32 disposed on its surface 31a. The second circuit component 40 includes a second circuit substrate 41 and a second electrode 42 disposed on its surface 41a. An insulating resin layer 55 filled between the circuit components 30 and 40 maintains the state in which the first circuit component 30 and the second circuit component 40 are attached, and maintains the state in which the first electrode 32 and the second electrode 42 are electrically connected.

[0133] Specific examples of circuit components 30 and 40 include chip assemblies such as IC chips (semiconductor chips), resistor chips, capacitor chips, and driver ICs; and rigid packaging substrates. These circuit components have circuit electrodes, typically multiple circuit electrodes. Another specific example of circuit components 30 and 40 includes wiring substrates such as flexible strips with metal wiring, flexible printed wiring boards, and glass substrates with indium tin oxide (ITO) vapor deposition.

[0134] Specific examples of the first electrode 32 or the second electrode 42 include copper, copper / nickel, copper / nickel / gold, copper / nickel / palladium, copper / nickel / palladium / gold, copper / nickel / gold, copper / palladium, copper / palladium / gold, copper / tin, copper / silver, indium tin oxide, and other electrodes. The first electrode 32 or the second electrode 42 can be formed by electroless plating, electrolytic plating, sputtering, or etching of metal foil.

[0135] In this embodiment, at least one of the first electrode 32 and the second electrode 42 is a gold electrode.

[0136] The junction 70 includes a first region 71 connecting the first electrode 32 and the second electrode 42, and a second region 72 in contact with the first region. In this embodiment, through the contact of molten solder with the gold electrode, a portion of the gold in the gold electrode forms an alloy (tin-gold alloy) with the tin in the solder, which can be considered to form the first region 71. Furthermore, bismuth in the solder is extruded from the first region 71, which can be considered to form the second region 72 surrounding the first region 71.

[0137] The first region 71 may be made of tin-gold alloy, and the second region 72 may be made of bismuth.

[0138] The ratio V2 / V1 of the volume V2 of the second region 72 to the volume V1 of the first region 71 can be, for example, 0.05 to 2.0, preferably 0.1 to 1.5, and more preferably 0.18 to 1.0.

[0139] In the connecting structure, among the multiple joints, the proportion of joints 70 including the first region 71 and the second region 72 is 90% or more, preferably 95% or more, more preferably 99% or more, and can be 100%. In addition, as a joint that does not include the first region 71 and the second region 72, for example, a joint having a columnar portion made of a tin-bismuth alloy can be cited.

[0140] Figure 15 (a) Figure 15 (b) Figure 15 (c) Figure 15 (d) Figure 16 (a) Figure 16 (b) Figure 16 (c) and Figure 16 (d) are cross-sectional views in the stacking direction, schematically showing an example of the junction including the first region 71 and the second region 72.

[0141] like Figure 15 As shown in (a), in the joint 70, the first region 71 may have a columnar structure connecting the first electrode 32 and the second electrode 42, and the second region 72 may have an annular structure surrounding the first region 71. Figure 15 (a) The cross-section shown is perpendicular to the stacking direction of the joint 70. For example, it can be as follows: Figure 17 The structure shown in (a) is as follows.

[0142] like Figure 15 As shown in (b), in the joint 70, the first region 71 may have a columnar structure connecting the first electrode 32 and the second electrode 42, and the second region 72 may be a block that contacts a part of the first region 71. Figure 15 (b) The cross-section perpendicular to the stacking direction of the joint 70 shown can be, for example, as... Figure 17 The structure shown in (b)

[0143] like Figure 15 As shown in (c), the junction 70 may include a plurality of first regions 71 having columnar structures connecting the first electrode 32 and the second electrode 42. Furthermore, in this junction 70, the second regions 72 may be configured among the plurality of first regions 71 in such a way that the plurality of first regions 71 connect to each other. Figure 15 (c) The cross-section perpendicular to the stacking direction of the joint 70 shown can be, for example, as... Figure 17 The structure shown in (c) is as follows.

[0144] like Figure 15 As shown in (d), in the joint 70, the first region 71 has a columnar structure connecting the first electrode 32 and the second electrode 42. Furthermore, in addition to the columnar structure, the joint 70 may also have a blocky body containing a tin-gold alloy. Figure 15 As shown in (d), the block can be integrated with the first region 71 to form part of the first region 71 (i.e., the first region 71 has columnar portions and block portions), or it can exist separately from the first region 71. In the former case, the second region 72 can be configured to contact either the columnar portion or the block portion of the first region 71; in the latter case, the second region 72 can be configured to contact both the first region 71 and the block. Figure 15 (c) The cross-section perpendicular to the stacking direction of the joint 70 shown can be, for example, as... Figure 17 (c) or Figure 17 The structure shown in (d) is as follows.

[0145] like Figure 16As shown in (a), in the junction 70, the first region 71 may have a columnar structure connecting the first electrode 32 and the second electrode 42, and the second region 72 may have an annular structure surrounding the first region 71. Furthermore, in addition to the annular structure, the junction 70 may also have a blocky body containing bismuth. Figure 16 As shown in (a), the block can be integrated with the second region 72 to form part of the second region 72 (i.e., the second region 72 has an annular portion and a block portion), or it can be separated from the annular second region 72 and contact the first region 71 as another second region 72. Figure 16 (a) The cross-section shown is perpendicular to the stacking direction of the joint 70, for example, as shown below. Figure 17 The structure shown in (d) is as follows.

[0146] like Figure 16 As shown in (b), in the junction 70, the first region 71 may have a columnar structure connecting the first electrode 32 and the second electrode 42, and the second region 72 may have an annular structure surrounding a portion of the first region 71. Furthermore, the first region 71 may extend along the electrode surface of the first electrode 32 or the second electrode 42.

[0147] like Figure 16 (c) or Figure 16 As shown in (d), the joint 70 can be formed by integrating multiple solder particles 1 (or solder bumps). Figure 16 As shown in (c), the joint 70 may include a first region 71 with a columnar structure formed by the unification of a plurality of solder particles 1, and may also include an annular second region 72 surrounding the first region 71. Furthermore, as... Figure 16 As shown in (d), the joint 70 may have a plurality of first regions 71 originating from each of a plurality of solder particles 1 (or solder bumps), and the plurality of first regions 71 may also be connected by a second region 72. Figure 16 (c) The cross-section perpendicular to the stacking direction of the joint 70 shown can be, for example, as... Figure 17 The structure shown in (e) is also present. Figure 16 (d) shows a cross-section perpendicular to the stacking direction of the joint 70, for example, such as... Figure 17 The structure shown in (f) is as follows.

[0148] Secondly Figure 18 (a) Figure 18 (b) and Figure 18 (c) are cross-sectional views of the stacking direction, schematically showing an example of the junction excluding the first region and the second region.

[0149] exist Figure 18In the joint 90 shown in (a), the tin-gold alloy region 91 is biased on each side of the first electrode 32 and the second electrode 42, and cannot connect the first electrode 32 and the second electrode 42. Furthermore, a bismuth-containing region 92 is formed between the region 91 on the first electrode 32 side and the region 91 on the second electrode 42 side. Figure 18 Since the joint 90 shown in (a) does not have a first region, it is not equivalent to "a joint including a first region and a second region". Figure 18 (a) The cross-section shown is perpendicular to the stacking direction of the joint 90. For example, it can be as follows: Figure 19 (a) Figure 19 (b) or Figure 19 The structure shown in (c) is as follows.

[0150] exist Figure 18 In the joint 90 shown in (b), the region 91 containing the tin-gold alloy is biased towards the second electrode 42, and a region 92 containing bismuth is formed between region 91 and the first electrode 32. Figure 18 In the joint 90 shown in (b), region 91 is not connected to the first electrode 32 and the second electrode 42, and is not equivalent to "joint including the first region and the second region". Figure 18 (a) The cross-section shown is perpendicular to the stacking direction of the joint 90. For example, it can be as follows: Figure 19 (a) Figure 19 (b) or Figure 19 The structure shown in (c) is as follows.

[0151] exist Figure 18 In the joint 90 shown in (c), the region 91 containing the tin-gold alloy and the region 92 containing the bismuth alloy are biased towards the second electrode 42, and the first electrode 32 and the second electrode 42 are not electrically connected. Furthermore, in Figure 18 In the joint 90 shown in (c), the alloying of gold and tin is insufficient, resulting in a tin-containing region 93 formed in region 92. Figure 18 In the joint 90 shown in (c), region 91 is not connected to the first electrode 32 and the second electrode 42, and is not equivalent to "a joint including the first region and the second region". Figure 18 (a) The cross-section shown is perpendicular to the stacking direction of the joint 90. For example, it can be as follows: Figure 19 (a) Figure 19 (b) Figure 19 (c) or Figure 19 The structure shown in (d) is as follows.

[0152] <Manufacturing Method of Connecting Structures>

[0153] refer to Figure 12 (a) and Figure 12(b) The manufacturing method of the connecting structure is explained. These figures schematically illustrate the formation... Figure 11 A cross-sectional view illustrating an example of the process of connecting structure 50A. First, prepare... Figure 1 The anisotropic conductive film 10 is shown, and it is configured such that the first circuit component 30 and the second circuit component 40 face each other. Figure 12 (a)). At this time, the first electrode 32 of the first circuit component 30 and the second electrode 42 of the second circuit component 40 are arranged opposite each other. Then, along the thickness direction of the stack of these components ( Figure 12 (a) Pressure is applied in the direction of arrows A and B shown. When pressure is applied in the direction of arrows A and B, the solder particles 1 are melted and aggregated between the first electrode 32 and the second electrode 42 by heating the whole to a temperature at least higher than the melting point of the solder particles 1 (e.g., 130 to 260°C) to form a joint 70. Then, the joint 70 is fixed between the first electrode 32 and the second electrode 42 by cooling, and the first electrode 32 and the second electrode 42 are electrically connected.

[0154] When the insulating resin composition constituting the insulating film 2 includes, for example, a thermosetting resin, the insulating resin composition can be cured by heating the entire assembly when pressure is applied in the directions of arrows A and B. Thus, an insulating resin layer 55 composed of the cured insulating resin composition is formed between the circuit components 30 and 40.

[0155] Figure 13 (a) and Figure 13 (b) For illustrative purposes Figure 12 (a) and Figure 12 (b) is a cross-sectional view of a modified method for manufacturing the connection structure 50A shown. In this modified method, a portion of the solder particles 1 does not contribute to the welding of electrodes 32 and 42 and remains in the insulating resin layer 55. However, the solder particles 1 are only disposed at specific locations in the anisotropic conductive film 10. That is, since the density of the solder particles 1 is low enough, high insulation reliability can be maintained.

[0156] Figure 14 (a) and Figure 14 (b) For illustrative purposes Figure 12 (a) and Figure 12 (b) is a cross-sectional view of a modified method for manufacturing the connection structure 50A shown. In this modified method, virtually all solder particles 1 become joints 70, and the first electrode 32 of the first circuit component 30 is fused with the second electrode 42 of the second circuit component 40. By pre-designing the configuration of the solder particles 1 in the anisotropic conductive film 10, the amount of solder particles 1 that do not contribute to fusion can be minimized. As a result, the insulation reliability of the connection structure can be further improved.

[0157] The above describes the method for manufacturing the connection structure of this embodiment using the anisotropic conductive film 10. However, the connection structure of this embodiment can be manufactured without using the anisotropic conductive film.

[0158] For example, in another embodiment of the manufacturing method of the connection structure, a solder bump is formed on the surface of the first electrode 32 of the first circuit component 30 (or the second electrode 42 of the second circuit component 40), the first electrode 32 (or the second electrode 42) with the solder bump is arranged in an opposing position, and the first electrode 32 and the second electrode 42 are connected by heating and pressure, thereby manufacturing the joint 70.

[0159] The method for forming solder bumps is not particularly limited. For example, a substrate 60 is prepared that contains solder particles 1 in each recess 62. The first electrode 32 of the first circuit component 30 is disposed opposite to the surface of the recess 62 on the opening side of the substrate 60, and heat treatment is performed while applying pressure along the thickness direction of the substrate, thereby forming solder bumps on the surface of the first electrode 32. Solder bumps can also be formed on the surface of the second electrode 42 in the same way.

[0160] The heat treatment is preferably performed, for example, in a deoxidizing or reducing environment. This suppresses the oxidation of solder particles and facilitates wetting and diffusion to the first electrode 32 (or the second electrode 42), enabling more reliable placement of solder bumps on the surface of the first electrode 32 (or the second electrode 42). The deoxidizing environment can be, for example, an inert gas environment such as nitrogen or argon, or a vacuum state.

[0161] From the viewpoint of more reliably positioning the solder bump on the surface of the first electrode 32 (or the second electrode 42), fluxes, adhesives, etc., can be used when forming the solder bump. However, these substances sometimes hinder the connection between the first electrode 32 and the second electrode 42, or sometimes oxidize or corrode the solder bump or electrode; therefore, a process for removing these substances after the bump is formed is possible.

[0162] The connection between the first electrode 32 and the second electrode 42 is preferably implemented, for example, in a deoxidizing or reducing environment. This suppresses solder particle oxidation and facilitates wetting and diffusion to both the first electrode 32 and the second electrode 42, resulting in a more reliable connection at the joint 70 between the two electrodes. The deoxidizing environment can be, for example, an inert gas environment such as nitrogen or argon, or a vacuum state.

[0163] From the viewpoint of more reliably manufacturing the first electrode 32 and the second electrode 42, fluxes, adhesives, etc., can be used when forming the joint 70. However, these can sometimes cause oxidation or corrosion of the joint or electrode, or sometimes have an adverse effect on the formation of the insulating resin layer 55 described later. Therefore, a process for removing these substances can be included after the joint 70 is formed.

[0164] In the above-described method of manufacturing the connecting structure, after forming the joint 70, an insulating resin material can be injected between the first circuit component 30 and the second circuit component 40 and cured to form an insulating resin layer 55.

[0165] In the above-described method of manufacturing the connecting structure, when forming the joint 70, a first circuit component 30 having a first electrode 32 with solder bumps and a second circuit component 40 having a second electrode 42 are arranged with the first electrode 32 facing the second electrode 42. Furthermore, an insulating resin film is disposed between the first circuit component 30 and the second circuit component 40, and heat treatment is performed while applying pressure in the thickness direction. This allows the joint 70 and the insulating resin layer 55 to be formed simultaneously.

[0166] Figure 20 , Figure 21 , Figure 22 and Figure 23 This diagram schematically illustrates the relationship between the position of the solder particles 1 on the anisotropic conductive film 10 and the position of the first electrode 32 before pressing and heating. Figure 20 , Figure 21 , Figure 22 and Figure 23 It can also be described as a diagram schematically showing the relationship between the position of the solder particles 1 in the substrate 60 when solder bumps are formed and the position of the first electrode 32 (or the second electrode 42).

[0167] Examples of suitable applications for the connection structures described above and their variations include connections for semiconductor memory, semiconductor logic chips, etc.; primary or secondary mounting connections for semiconductor packages; CMOS image elements, laser elements, LED light-emitting elements, etc.; or devices using these connections, such as cameras, sensors, liquid crystal displays, personal computers, mobile phones, smartphones, and tablet computers.

[0168] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

[0169] [Example]

[0170] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0171] <Production of Solder Particles>

[0172] (Production example 1)

[0173] (Process a1) Grading of solder particles

[0174] 100g of Sn-Bi solder particles (manufactured by 5N Plus Inc., melting point 139°C, Type 8) were immersed in distilled water, ultrasonically dispersed, and then allowed to stand. The solder particles floating in the supernatant were recovered. This operation was repeated to recover 10g of solder particles. The average particle size of the obtained solder particles was 1.0μm, and the CV value was 42%.

[0175] (Process b1) Configuration on the substrate

[0176] As shown in Table 1, a substrate (polyimide film, 100 μm thick) with multiple recesses was prepared. The recesses had an opening diameter of 2.3 μmφ, a bottom diameter of 2.0 μmφ, and a depth of 2.0 μm (when viewed from above, the bottom diameter of 2.0 μmφ is located in the center of the opening diameter of 2.3 μmφ). The multiple recesses were arranged regularly at 1.0 μm intervals. Solder particles (average particle size 1.0 μm, CV value 42%) obtained in step a were placed in the recesses of the substrate. In addition, excess solder particles were removed by rubbing the surface of the substrate with the recesses formed with a micro-adhesive roller, resulting in a substrate with solder particles disposed only in the recesses.

[0177] (Process c1) Formation of solder particles

[0178] The substrate in step b1, where solder particles are arranged in the recess, is placed in a hydrogen radical reduction furnace (manufactured by SHINKOSEIKICO.,LTD., a plasma reflow apparatus). After evacuation, hydrogen gas is introduced into the furnace to fill it. The furnace temperature is then adjusted to 120°C, and hydrogen radicals are irradiated for 5 minutes. The hydrogen gas is then removed by evacuation, and after heating to 170°C, nitrogen gas is introduced into the furnace to restore atmospheric pressure. The furnace temperature is then lowered to room temperature, thereby forming solder particles.

[0179] (Process d1) Recovery of solder particles

[0180] Solder particles were recovered from the recess by tapping the substrate that had passed through process c1 from the back side of the recess. The obtained solder particles were evaluated by the following method.

[0181] <Evaluation of Solder Particles>

[0182] Solder particles were mounted on a conductive strip fixed to the surface of a SEM observation base. The SEM observation base was then tapped onto a 5mm thick stainless steel plate to ensure uniform diffusion of the solder particles on the conductive strip. Compressed nitrogen gas was then sprayed onto the conductive strip surface to fix a single layer of solder particles onto it. The diameter of 300 solder particles was measured using SEM, and the average particle size and CV value were calculated. The results are shown in Table 2.

[0183] (Preparation examples 2 to 6)

[0184] Except for changing the recess dimensions as described in Table 1, solder particles were fabricated and evaluated in the same manner as in Fabrication Example 1. The results are shown in Table 2.

[0185] [Table 1]

[0186] Production example 1 Production example 2 Production example 3 Production example 4 Production example 5 Production example 6 Opening diameter μm 2.3 4.3 6.3 18 24 30 bottom diameter μm 2 4 6 16 22 28 depth μm 2 4 6 16 22 28 interval μm 1 2.3 4.6 8.6 11.5 17

[0187] [Table 2]

[0188] Production example 1 Production example 2 Production example 3 Production example 4 Production example 5 Production example 6 Average particle size μm 2.0 3.9 6.0 16.0 21.8 28.1 CV value ％ 18.8 7.6 6.5 4.1 3.7 3.1

[0189] <Example 1>

[0190] (A) Fabrication of anisotropic conductive films

[0191] (Process e1) Manufacturing of flux-coated solder particles

[0192] Solder particles were prepared using the same method as in Example 1. 20 g of the obtained solder particles, 4 g of adipic acid, and 7 g of acetone were weighed into a three-necked flask. Then, 0.03 g of dibutyltin oxide, which catalyzes the dehydration condensation reaction between the hydroxyl groups on the surface of the solder particles and the carboxyl groups of adipic acid, was added, and the reaction was carried out at 60°C for 4 hours. The solder particles were then filtered and recovered. In a three-necked flask, 5 g of the recovered solder particles, 20 g of toluene, and 0.03 g of p-toluenesulfonic acid were weighed, and the reaction was carried out at 120°C for 3 hours while simultaneously applying vacuum and reflowing. During this process, the reaction was carried out using a Dean-Stark extraction device to remove water generated by the dehydration condensation. The solder particles were then recovered by filtration, washed with hexane, and dried. The dried solder particles were pulverized using an air jet mill and passed through an ultrasonic sieve to obtain flux-coated solder particles.

[0193] (Process f1) Preparation of flux-coated solder particles

[0194] A transfer mold (polyimide film, 100 μm thick) with multiple recesses was prepared. The recesses have an opening diameter of 2.3 μmφ, a bottom diameter of 2.0 μmφ, and a depth of 2.0 μm (when viewed from above, the bottom diameter of 2.0 μmφ is located at the center of the opening diameter of 2.3 μmφ). Furthermore, the multiple recesses are arranged regularly at 1.0 μm intervals. Solder particles coated with flux, obtained in step e1, are disposed within the recesses of this transfer mold.

[0195] (Step g1) Fabrication of the adhesive membrane

[0196] A solution was prepared by dissolving 100g of phenoxy resin (manufactured by Union Carbide Corporation, trade name "PKHC") and 75g of acrylic rubber (a copolymer of 40 parts by weight of butyl acrylate, 30 parts by weight of ethyl acrylate, 30 parts by weight of acrylonitrile, and 3 parts by weight of glycidyl methacrylate, molecular weight: 850,000) in 400g of ethyl acetate. Then, 300g of liquid epoxy resin (epoxy equivalent 185, manufactured by Asahi Kasei Corporation, trade name "NOVACURE HX-3941") containing a microencapsulated latent curing agent was added to this solution and stirred to obtain an adhesive solution. The adhesive solution was then coated onto a diaphragm (a silicone-treated polyethylene terephthalate film, 40μm thick) using a roller coater and dried at 90°C for 10 minutes, thereby producing adhesive films (insulating resin films) with thicknesses of 2, 3, 4, 10, 15, and 20μm on the diaphragm.

[0197] (Process h1) Transfer of flux-coated solder particles

[0198] The adhesive film formed on the diaphragm is placed face to face with the transfer mold containing flux-coated solder particles in step f1, and the flux-coated solder particles are transferred onto the adhesive film.

[0199] (Process i1) Fabrication of anisotropic conductive film

[0200] The adhesive film prepared by the same method as in step g1 is brought into contact with the transfer surface of the adhesive film obtained in step h1, and subjected to a temperature of 50°C and a pressure of 0.1 MPa (1 kgf / cm²). 2Heating and pressurizing are applied to obtain an anisotropic conductive film in which flux-coated solder particles are arranged in layers in a cross-sectional view of the film. Furthermore, anisotropic conductive films with thicknesses of 4μm, 6μm, 8μm, 20μm, 30μm, and 40μm are fabricated by overlapping 2μm with a film thickness of 2μm, similarly overlapping 3μm with 3μm, 4μm with 4μm, 10μm with 10μm, 15μm with 15μm, and 20μm with 20μm.

[0201] (B) Fabrication of the connecting structure

[0202] (Process j1) Prepare evaluation chip

[0203] Seven types of chips with gold bumps (3.0×3.0mm, thickness: 0.5mm) were prepared as shown below.

[0204] • Chip C1… Area: 100μm × 100μm, Gap: 40μm, Height: 10μm, Number of bumps: 362

[0205] • Chip C2… Area: 75μm × 75μm, Gap: 20μm, Height: 10μm, Number of bumps: 362

[0206] • Chip C3… Area: 40μm × 40μm, Gap: 16μm, Height: 7μm, Number of bumps: 362

[0207] • Chip C4… Area: 30μm × 30μm, Gap: 12μm, Height: 6μm, Number of bumps: 362

[0208] • Chip C5… Area: 20μm × 20μm, Gap: 7μm, Height: 5μm, Number of bumps: 362

[0209] • Chip C6… Area: 10μm × 10μm, Gap: 6μm, Height: 3μm, Number of bumps: 362

[0210] (Process k1) Prepare the evaluation substrate

[0211] Seven types of substrates with gold bumps (70×25mm, thickness: 0.5mm) were prepared as shown below. In addition, lead wires for resistance measurement were formed on these gold bumps.

[0212] • Substrate D1… Area: 100μm × 100μm, Gap: 40μm, Height: 4μm, Number of bumps: 362

[0213] • Substrate D2… Area: 75μm × 75μm, Gap: 20μm, Height: 4μm, Number of bumps: 362

[0214] • Substrate D3… Area: 40μm × 40μm, Gap: 16μm, Height: 4μm, Number of bumps: 362

[0215] • Substrate D4… Area: 30μm × 30μm, Gap: 12μm, Height: 4μm, Number of bumps: 362

[0216] • Substrate D5… Area: 20μm × 20μm, Gap: 7μm, Height: 4μm, Number of bumps: 362

[0217] • Substrate D6… Area: 10μm × 10μm, Gap: 6μm, Height: 3μm, Number of bumps: 362

[0218] (Process l1)

[0219] Next, using the anisotropic conductive film fabricated in process i1, the evaluation chip (3.0×3.0mm, thickness: 0.5mm) and the evaluation substrate (thickness: 0.5mm) are connected in the order shown below i) to iii), thereby obtaining the connection structure.

[0220] i) Peel off the single-sided separator (silicone-treated polyethylene terephthalate film, 40 μm thick) from the anisotropic conductive film (3.5 × 19 mm), bringing the anisotropic conductive film into contact with the evaluation substrate, and then test it at 80 °C and 0.98 MPa (10 kgf / cm²). 2 It was attached below.

[0221] ii) The diaphragm was peeled off, and the bumps of the evaluation chip and the bumps of the evaluation substrate were aligned.

[0222] iii) The chip was heated and pressurized from above under the conditions of 180°C, 40gf / bump, and 10 seconds, and then formally connected. By combining the “chip / anisotropic conductive film / substrate” of (1) to (6) below, seven connection structures of (1) to (6) were fabricated respectively.

[0223] (1) Chip C1 / 40μm thick anisotropic conductive film / substrate D1

[0224] (2) Chip C2 / 30μm thick anisotropic conductive film / substrate D2

[0225] (3) Chip C3 / 20μm thick anisotropic conductive film / substrate D3

[0226] (4) Chip C4 / 8μm thick anisotropic conductive film / substrate D4

[0227] (5) Chip C5 / 6μm thick anisotropic conductive film / substrate D5

[0228] (6) Chip C6 / 4μm thick anisotropic conductive film / substrate D6

[0229] <Evaluation of the connection structure>

[0230] For a portion of the obtained connection structure, conduct continuity resistance and insulation resistance tests are performed as follows.

[0231] (Conductivity Resistance Test - Moisture Absorption and Heat Resistance Test)

[0232] Regarding the conduction resistance between the chip (bump) with gold bumps and the substrate (bump) with gold bumps, the initial value of the conduction resistance and the value after moisture absorption and heat resistance tests (placed at 85°C and 85% humidity for 100, 500, and 1000 hours) were measured for 20 samples, and their average value was calculated.

[0233] Based on the obtained average values, the on-resistance was evaluated according to the following criteria. The results are shown in Table 3. Furthermore, after 1000 hours of moisture absorption and heat resistance testing, if criteria A or B below are met, the on-resistance is considered good.

[0234] A: The average on-resistance is less than 2Ω

[0235] B: The average on-resistance is above 2Ω and less than 5Ω.

[0236] C: The average on-resistance is above 5Ω and below 10Ω

[0237] D: The average on-resistance is above 10Ω and below 20Ω.

[0238] E: Average on-resistance is above 20Ω

[0239] (Continuity Resistance Test - High Temperature Placement Test)

[0240] Regarding the on-resistance between the chip (bump) and the substrate (bump) with gold bumps, the initial value and the value after high-temperature placement tests (placed at 100°C for 100, 500, and 1000 hours) were measured for 20 samples. Additionally, after high-temperature placement, a drop impact was applied, and the on-resistance of the samples after the drop impact was measured. The drop impact was generated by screwing the connection structure to a metal plate and dropping it from a height of 50 cm. After the drop, the DC resistance value was measured at the solder joint at the chip corner where the impact was greatest (4 locations). A breakage was considered to have occurred when the measured value increased more than 5 times from the initial resistance, and this was evaluated. Furthermore, measurements were performed at a total of 80 locations across the 4 locations for each sample. The results are shown in Table 4. After 20 drop cycles, the solder joint reliability was evaluated as good if it met either criterion A or B below.

[0241] A: There are 0 solder joints where the initial resistance increases by more than 5 times.

[0242] B: There are more than one but less than five solder joints where the initial resistance increases by more than five times.

[0243] C: There are 6 to 20 solder joints where the initial resistance increases by more than 5 times.

[0244] D: There are 21 or more solder joints where the initial resistance is increased by more than 5 times.

[0245] (Insulation resistance test)

[0246] Regarding the insulation resistance between chip electrodes, the initial value and the value after migration tests (placed for 100, 500, and 1000 hours under conditions of 60°C, 90% humidity, and 20V) were measured for 20 samples. The insulation resistance value was calculated to be 10 for all 20 samples. 9 The proportion of samples with an Ω or higher was determined. Based on the obtained proportions, the insulation resistance was evaluated according to the following criteria. The results are shown in Table 5. Furthermore, after 1000 hours of migration testing, a condition meeting either criterion A or B below is considered to have good insulation resistance.

[0247] A: Insulation resistance value 10 9 The proportion of Ω and above is 100%.

[0248] B: Insulation resistance value 10 9 The proportion of Ω and above is 90% or more but less than 100%.

[0249] C: Insulation resistance value 10 9 The proportion of Ω and above is 80% or more but less than 90%.

[0250] D: Insulation resistance value 10 9 The proportion of Ω and above is 50% or more but less than 80%.

[0251] E: Insulation resistance value 10 9 The proportion of Ω and above is less than 50%.

[0252] <Examples 2-6>

[0253] Except for using solder particles made in the same way as in Examples 2 to 6, and using a transfer mold of the same shape as the substrate used to make the solder particles in Examples 2 to 6, the anisotropic conductive film and the connecting structure were made in the same way as in Example 1.

[0254] [Table 3]

[0255]

[0256] [Table 4]

[0257]

[0258] [Table 5]

[0259]

[0260] <Evaluation of the connection structure>

[0261] After fixing the connection structure for evaluation with epoxy molding resin, it was cut with a fine saw and polished with polishing paper until the connection cross-section of the gold bumps of the evaluation chip, solder particles, and gold bumps of the evaluation substrate was visible. Then, the connection cross-section was processed into a flat surface using a low-temperature polishing apparatus (IB-19520CCP, manufactured by JEOL Ltd.) at -120°C or below and 4.0kV. A 5nm-thickness platinum layer was formed in this cross-section by sputtering, and SEM observation and EDX analysis were performed. As a result, in Example 2 (5), it was confirmed that immediately after the connection structure was formed, the gold bumps of the evaluation chip and the gold bumps of the evaluation substrate maintained a constant distance and were connected via a gold and tin alloy layer. Furthermore, a bismuth portion was present at the location in contact with this alloy layer. The SEM image of the cross-section is shown below. Figure 25 In (a), the EDX analysis results of the profile are shown in Figure 25 (b) In the cross-sectional structure after the evaluation test, the gold and tin alloy layer extended towards each gold bump side, but remained almost unchanged compared to before the test.

[0262] In Examples 1-6, the solder particles are held by the insulating resin portion, and gaps are maintained between the gold bumps. The tin component of the solder is alloyed with the gold and the bismuth is reconfigured within an appropriate heating time, thereby a stable connection structure is considered to be obtained.

[0263] <Fabrication of Solder Bump Forming Components>

[0264] (Production example 7)

[0265] (Process m1) Substrate fabrication

[0266] A liquid photoresist (manufactured by ShowaDenko Materials Co., Ltd., AH series) was spin-coated to a thickness of 1.5 μm onto a 6-inch silicon wafer. The photoresist on the silicon wafer was exposed and developed to obtain a substrate 7 with recesses. The recesses have an opening diameter of 2.3 μmφ, a bottom diameter of 2.0 μmφ, and a depth of 1.5 μm (when viewed from above, the bottom diameter of 2.0 μmφ is located at the center of the opening diameter of 2.3 μmφ). These recesses are positioned relative to the electrode arrangement pattern of the evaluation substrate 7. Alignment marks at three locations were formed on the surface of the substrate 7 while the recesses were being formed. A summary of the substrate 7 is shown in Table 6.

[0267] [Table 6]

[0268] Matrix 7 Matrix 8 Matrix 9 Matrix 10 Matrix 11 Matrix 12 Opening diameter μm 3.1 6.3 6.0 16.3 23.1 33.3 bottom diameter μm 2.0 4.0 6.5 4.1 3.7 3.1 depth μm 1.0 3.0 1.5 4.3 6.6 8.3 X-direction spacing μm 16 32 48 144 192 280 Y-direction spacing μm 8 16 24 72 96 140

[0269] In addition to obtaining solder particles in the same way as in step a1 and using the substrate 7, solder particles are arranged in the recess in the same way as in step b1, and a solder bump forming component 7 having solder particles in the recess is obtained by step c1.

[0270] <Evaluation of Solder Bump Forming Components>

[0271] A portion of the solder bump forming component 7 was fixed to the surface of a SEM observation base, and platinum sputtering was performed on the surface. The diameter of 300 solder particles was measured using SEM, and the average particle size and CV value were calculated. The results are shown in Table 7. Furthermore, the surface shape of a portion of the solder bump forming component 7 was measured using a laser microscope (manufactured by Olympus Corporation, LEXTOLS5000-SAF), the height of the solder particles from the substrate surface was measured, and the average value of 300 particles was calculated. The results are shown in Table 7.

[0272] [Table 7]

[0273] Production example 7 Production example 8 Production example 9 Production example 10 Production example 11 Production example 12 Average particle size μm 2.1 4.0 6.1 15.9 21.0 32.0 CV value ％ 18.0 7.5 6.9 4.7 4.0 3.4 high μm 0.6 1.0 1.6 3.9 4.5 7.0

[0274] (Preparation examples 8 to 12)

[0275] The thickness of the photosensitive resist was changed to the depth values ​​shown in Table 6, and the recess dimensions were also changed as described in Table 6. The recess placement was set relative to the electrode arrangement pattern of the evaluation substrate described in Table 6. Otherwise, the solder bump forming component was fabricated using the same method as in Example 7 and evaluated. The results are shown in Table 7.

[0276] <Fabrication of Evaluation Chips with Solder Bumps>

[0277] (Process j2) Prepare the evaluation chip

[0278] Six types of chips with gold bumps (5×5mm, thickness: 0.5mm) were prepared as shown below.

[0279] Chip C7… Electrode dimensions: 8μm × 4μm, Spacing: 16μm in the X direction, 8μm in the Y direction, Number of bumps: 180,000

[0280] Chip C8… Electrode dimensions: 16μm × 8μm, Spacing: 32μm in the X direction, 16μm in the Y direction, Number of bumps: 46,000

[0281] Chip C9… Electrode dimensions: 24μm × 12μm, Spacing: 48μm in the X direction, 24μm in the Y direction, Number of bumps: 15,000

[0282] Chip C10… Electrode dimensions: 72μm × 36μm, Spacing: 144μm in the X direction, 72μm in the Y direction, Number of bumps: 3400

[0283] Chip C11… Electrode dimensions: 96μm × 48μm, Spacing: 192μm in the X direction, 96μm in the Y direction, Number of bumps: 850

[0284] Chip C12… Electrode dimensions: 140μm × 70μm, Spacing: 280μm in the X direction, 140μm in the Y direction, Number of bumps: 420

[0285] (Process n1) Forming solder bumps

[0286] On the FC3000W (manufactured by TORAY ENGINEERING Co., Ltd.) platform, a solder bump forming component 7 is placed. An evaluation chip C8 is mounted on the head and picked up. Using two alignment marks, the solder particles positioned in the recess of the solder bump forming component 7 are aligned with the electrodes of the evaluation chip C8. An evaluation chip C7 is temporarily placed on the solder bump forming component 7. Then, it is placed on the lower hot plate of a formic acid reflow oven (manufactured by SHINKO SEIKI CO.,LTD., intermittent vacuum soldering equipment). After evacuation, formic acid gas is filled, and the lower hot plate is heated to 145°C for 1 minute. Then, after evacuating the formic acid gas, nitrogen purging is performed, the lower hot plate is returned to room temperature, and the oven interior is opened to the atmosphere. Solder particles are transferred onto the electrodes of the evaluation chip C7, thus forming a solder bump.

[0287] <Evaluation of Solder Bumps>

[0288] For the evaluation chip obtained after process n1, the number of solder particles that could be transferred to 300 electrodes (number of solder bumps) was counted, and the transfer rate was calculated. Furthermore, the height of the solder bumps was measured using a laser microscope (manufactured by Olympus Corporation, LEXT OLS5000-SAF), and the average value of the 300 measurements was calculated. The results are shown in Table 8.

[0289] [Table 8]

[0290]

[0291] Except for forming films 8-12 using solder bumps and evaluating chips C8-C12, solder bumps were formed using the same method as in process n1. Furthermore, the solder bumps of 300 electrodes were evaluated to calculate the transfer rate and average height. The results are shown in Table 8.

[0292] <Construction of Connecting Structures>

[0293] (Process k2) Prepare the evaluation substrate

[0294] Six types of evaluation substrates with gold bumps (70×25mm, thickness: 0.5mm) were prepared as shown below. The gold bumps are positioned opposite the gold electrodes on the evaluation chips C7 to C12 and are equipped with alignment marks. Furthermore, resistance measurement leads are formed on a portion of the gold bumps.

[0295] Substrate D7… Area: 8μm × 4μm, Spacing: 16μm in X direction, 8μm in Y direction, Height: 2μm, Number of bumps: 180,000

[0296] Substrate D8… Area 16μm × 8μm, Spacing: 32μm in X direction, 16μm in Y direction, Height: 3μm, Number of bumps: 46,000

[0297] Substrate D9… Area 24μm × 12μm, Spacing: X-direction 48μm, Y-direction 24μm, Height: 3μm, Number of bumps: 15,000

[0298] Substrate D10… Area 72μm × 36μm, Spacing: X-direction 144μm, Y-direction 72μm, Height: 3μm, Number of bumps: 3400

[0299] Substrate D11… Area: 96μm × 48μm, Spacing: 192μm in X direction, 96μm in Y direction, Height: 3μm, Number of bumps: 850

[0300] Substrate D12… Area 140μm × 70μm, Spacing: X-direction 280μm, Y-direction 140μm, Height: 3μm, Number of bumps: 420

[0301] (Process and O1) Joining Electrodes

[0302] The evaluation chip with solder bumps and the evaluation substrate with gold bumps, which were fabricated in process n1, were connected via solder bumps in the order shown in i) to iii).

[0303] i) Place the evaluation substrate D7 with gold bumps on the platform of FC3000W (manufactured by TORAY ENGINEERING Co., Ltd). Pick up the evaluation chip C7 with solder bumps at the head. Use two alignment marks to align the gold electrodes with each other. Place the evaluation chip C7 with solder bumps on the evaluation substrate D7 with gold bumps to obtain the sample 7 before bonding.

[0304] ii) The pre-bonding sample 7 obtained in i) is placed on the lower hot plate of a formic acid reflow oven (manufactured by SHINKO SEIKI CO.,LTD., intermittent vacuum welding equipment).

[0305] iii) Operate the formic acid vacuum reflow oven. After evacuation, fill with formic acid gas, raise the lower hot plate to 160°C and heat for 5 minutes. Then, after evacuating the formic acid gas, perform nitrogen purging to allow the lower hot plate to return to room temperature, and open the oven interior to the atmosphere. Add an appropriate amount of viscosity-adjusted underfill material (manufactured by Showa Denko Materials Co., Ltd., CEL series) between the evaluation chip and the evaluation substrate. After filling by vacuum evacuation, cure at 125°C for 3 hours to create the connection structure between the evaluation chip and the evaluation substrate. The combination of materials used to create the connection structure is as follows.

[0306] (7) Chip C7 / Solder bump forming component 7 / Substrate D7

[0307] (8) Chip C8 / Solder bump forming component 8 / Substrate D8

[0308] (9) Chip C9 / Solder bump forming component 9 / Substrate D9

[0309] (10) Chip C10 / Solder bump forming component 10 / Substrate D10

[0310] (11) Chip C11 / Solder bump forming component 11 / Substrate D11

[0311] (12) Chip C12 / Solder bump forming component 12 / Substrate D12

[0312] <Evaluation of the connection structure>

[0313] A portion of the obtained connection structure was subjected to continuity resistance and insulation resistance tests using the same method as described above. The results are shown in Tables 9, 10, and 11.

[0314] [Table 9]

[0315]

[0316] [Table 10]

[0317]

[0318] [Table 11]

[0319]

[0320] <Preparation Examples 13~18>

[0321] After the substrate is fabricated in process m1, the evaluation chip is prepared in process j2, and the solder bumps are formed in process n1, the evaluation chips C7 to C12 with solder bumps as shown in Table 8 are obtained.

[0322] <Construction of Connecting Structures>

[0323] In the order shown below (i) to (iii), the evaluation chip with solder bumps fabricated in process n1 and the evaluation substrate with gold bumps prepared in process k2 are connected via solder bumps.

[0324] i) Place the evaluation substrate with gold bumps on a spin coater and apply liquid flux (NS-334, manufactured by Nihon Superior Co., Ltd.) to the gold bump side.

[0325] ii) The evaluation substrate with gold bumps obtained in i) is placed on the FC3000W (manufactured by TORAY ENGINE ERING Co., Ltd) platform. The evaluation chip with solder bumps is picked up by the head and the gold electrodes are aligned with each other using two alignment marks. The evaluation chip with solder bumps is then placed on the evaluation substrate with gold bumps to obtain samples 13 to 18 before bonding.

[0326] iii) Place the sample before bonding on the lower hot plate of the formic acid reflow oven (manufactured by SHINKO SEIKI CO.,LTD., intermittent vacuum welding equipment).

[0327] iv) Start the formic acid vacuum reflow oven, fill it with nitrogen after evacuation, heat the lower hot plate to 160°C and heat for 3 minutes. Then, after evacuation, perform nitrogen replacement to allow the lower hot plate to return to room temperature, and open the oven interior to the atmosphere.

[0328] v) Immerse the bonding sample in an isopropyl solution to rinse away flux residue.

[0329] vi) An appropriate amount of underfill material with adjusted viscosity (manufactured by ShowaDenko Materials Co., Ltd., CEL series) is added between the evaluation chip and the evaluation substrate. After filling by vacuum, it is cured at 125°C for 3 hours to create the connection structure between the evaluation chip and the evaluation substrate. The combination of materials used to make the connection structure is as follows.

[0330] (13) Chip C7 / Solder bump forming component 7 / Substrate D7

[0331] (14) Chip C8 / Solder bump forming component 8 / Substrate D8

[0332] (15) Chip C9 / Solder bump forming component 9 / Substrate D9

[0333] (16) Chip C10 / Solder bump forming component 10 / Substrate D10

[0334] (17) Chip C11 / Solder bump forming component 11 / Substrate D11

[0335] (18) Chip C12 / Solder bump forming component 12 / Substrate D12

[0336] <Evaluation of the connection structure>

[0337] A portion of the obtained connection structure was subjected to continuity resistance and insulation resistance tests using the same method as described above. The results are shown in Tables 12, 13, and 14.

[0338] [Table 12]

[0339]

[0340] [Table 13]

[0341]

[0342] [Table 14]

[0343]

[0344] Symbol Explanation

[0345] 1-Solder particle, 2-Insulating film, 2a-Insulating resin material, 2b-First resin layer, 2c-Surface of the first resin layer, 2d-Second resin layer, 10-Anisotropic conductive film, 30-First circuit component, 31-First circuit substrate, 32-First electrode, 40-Second circuit component, 41-Second circuit substrate, 42-Second electrode, 55-Insulating resin layer, 60-Substrate, 62-Recess, 70-Joint, 71-First region, 72-Second region, 80-Intermediate layer, 111-Solder particle.

Claims

1. A connecting structure, comprising: A first circuit component has multiple first electrodes; A second circuit component having multiple second electrodes; and The intermediate layer has multiple junctions that electrically connect the first electrode and the second electrode. At least one of the first electrode and the second electrode connected by the junction is a gold electrode. More than 90% of the plurality of said joints include: The first region has a columnar structure connecting the first electrode and the second electrode and contains a tin-gold alloy. And a second region, which is in contact with the first region and contains bismuth.

2. The connection structure according to claim 1, wherein, The intermediate layer also has an insulating resin layer that seals the space between the first circuit component and the second circuit component.

3. A method for manufacturing a connecting structure, comprising: The preparation process includes preparing a first circuit component having multiple first electrodes, a second circuit component having multiple second electrodes, and an anisotropic conductive film. In the configuration step, the first circuit component, the second circuit component, and the anisotropic conductive film are arranged such that the surface of the first circuit component having the first electrode and the surface of the second circuit component having the second electrode are facing each other across the anisotropic conductive film, thereby obtaining a laminate in which the first circuit component, the anisotropic conductive film, and the second circuit component are sequentially stacked; and In the joining process, the laminate is heated while being pressed along its thickness direction, thereby electrically connecting the first electrode and the second electrode via a joint. At least one of the first electrode and the second electrode is a gold electrode. The anisotropic conductive film includes an insulating film composed of an insulating resin composition and a plurality of solder particles disposed in the insulating film. The solder particles contain a tin-bismuth alloy, the average particle size of the solder particles is 1 μm to 30 μm, and the CV value of the solder particles is less than 20%. In the longitudinal section of the anisotropic conductive film, the solder particles are arranged laterally in a state of separation from adjacent solder particles. More than 90% of the plurality of joints formed in the connection process include: a first region having a columnar structure that connects the first electrode and the second electrode and contains a tin-gold alloy; And a second region, which is in contact with the first region and contains bismuth.

4. The manufacturing method according to claim 3, wherein, The solder particles are solder particles manufactured by the following method, which includes: The solder particle preparation process involves preparing a substrate with multiple recesses and solder particles containing a tin-bismuth alloy. The storage process involves storing at least a portion of the solder particles in the recess; and The fusion process fuses the solder particles housed in the recess, forming solder particles inside the recess.

5. The manufacturing method according to claim 4, wherein, The CV value of the solder particles prepared in the solder particle preparation process exceeds 20%.

6. The manufacturing method according to any one of claims 3 to 5, wherein, The anisotropic conductive film is an anisotropic conductive film manufactured by the following method, which includes: In the transfer process, an insulating resin composition is brought into contact with the opening side of the recess of a substrate having a plurality of recesses containing the solder particles, thereby obtaining a first resin layer transferred with the solder particles; and In the lamination process, a second resin layer composed of an insulating resin composition is formed on the surface of the first resin layer on the side where the solder particles are transferred, thereby obtaining an anisotropic conductive film.

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