JP2020109739A - Conductive particle, conductive material and connection structure using the same - Google Patents

Abstract

To provide conductive particles for manufacturing an anisotropic conductive material and a connection structure which have a low initial electric resistance and a low temperature rise after high temperature/high humidity reliability test.SOLUTION: Conductive particles have an oxide film provided on a surface of at least one electrode among electrodes as particles between particles that are contained between the electrodes and electrically connect the electrodes. In the conductive particles, a deformation ratio of the conductive particles when the conductive particles are compressed at 25°C using a micro compression tester, including a conductive layer provided on surfaces of an insulation core and a core and a conductive layer having a projection on the surface of the core is defined as an x axis, and a ratio of an elastic part of push-in processing defined as the following expression 1 is defined as a y axis, in a plotted graph, the oxide film is penetrated or destroyed by the conductive layer or the conductive layer having the projection in ranges of the ratio of the elastic part of the push-in processing and the deformation ratio of the conductive particles between a section (a) where the ratio of the elastic part of the push-in processing is kept constant after a first non-continuous point and a section (b) where the ratio of the elastic part of the push-in processing is kept constant after a second non-continuous point.SELECTED DRAWING: Figure 2

Description

The present invention relates to conductive particles having a conductive layer on the surface of an insulating core, and more specifically, to the conductivity of a conductive material that electrically connects an electrode of a chip on which an electronic device is mounted and an electrode of a substrate. The present invention relates to conductive particles used as a body, a conductive material, and a connection structure.

The conductive particles are an anisotropic conductive material used in the form of being mixed and mixed with a curing agent, an adhesive and a resin binder, for example, an anisotropic conductive film (Anisotropic Conductive Film), an anisotropic conductive adhesive (Anisotropic). Conductive Adhesive), anisotropic conductive paste (Anisotropic Conductive Paste), anisotropic conductive ink (Anisotropic Conductive Ink), anisotropic conductive sheet (Anisotropic Conductive Sheet), etc.

The anisotropic conductive material includes film-on-glass (FOG; flexible substrate-glass substrate), chip-on-film (COF; semiconductor chip-flexible substrate), chip-on-glass (COG; semiconductor chip-glass substrate), film-on-board. (FOB; flexible substrate-glass epoxy substrate) etc.

As for the anisotropically conductive material, for example, assuming that a semiconductor chip and a flexible substrate are bonded together, an anisotropic conductive material is arranged on the flexible substrate and a semiconductor chip is arranged on the anisotropic conductive material. After that, the anisotropic conductive material is cured under pressure and heat to mount the connection structure for the conductive particles to electrically connect the electrode of the semiconductor chip and the electrode of the substrate.

The conductive particles, when used in the anisotropic conductive material, is used by mixing the conductive particles with a curing agent, an adhesive, a resin binder, etc., and when it becomes a connection structure after pressurization/heating. Will maintain the electrical connection between the top and bottom electrodes by curing/bonding the anisotropic conductive material.

From the viewpoint of the energy efficiency of electronic devices when maintaining the electrical connection between electrodes, the connection resistance should be low initially and the increase in resistance should be low after high temperature and high humidity evaluation, for example, 85°C/85% reliability evaluation. Is advantageous. That is, one of the most important points for the performance of the conductive particles used for the anisotropic conductive material is low initial resistance and low low resistance increase after reliability evaluation.

For example, patents such as Japanese Patent Nos. 3581616, 4052832, 4113403, 408137, and 3914206 disclose Ni-Ag as a metal having low resistance in a conventional conductive layer in order to realize low resistance. , Ni-Cu, Ni-Au, Ni-B, Ni-P, or the like, or Pt, Au, Pd, W, Co, Ag, or the like is used as a highly reliable metal in the outermost periphery of the conductive layer. The method of use is presented. Patents such as Japanese Patent Nos. 4674096, 4593302, 4860163, 3083535, 4718926, and 4589810 easily penetrate the oxide film of the electrode to obtain resistance. Proposing a way to lower it.

Further, patents such as Japanese Patent Nos. 3898510, 4278374, 4593302, 4593302, 4674119, 5421982, and 6049461 provide methods utilizing the strength and recovery rate of conductive particles. There is. However, these methods have a limit in achieving the junction resistance of the anisotropic conductive material effective as a method using only a part of the physical properties of the conductive particles.

For example, if there are projections of conductive particles and the strength during compression is high, it is easy to penetrate through the oxide film of the electrode and enter. However, if only the strength of the conductive particles having protrusions is high, it is difficult to reduce both the connection resistance and the reliability resistance. This is because the joining of anisotropic conductive materials usually has a mechanism in which the resin of anisotropic conductive materials is cured over time under pressure/heating conditions. In other words, since it takes a certain amount of time rather than instantaneous curing, it should be taken into consideration that the elastic resistance of the conductive particles is low and the connection resistance is low until the resin of the anisotropic conductive material is completely cured. This is because an anisotropic conductive material can be mounted.

Japanese Patent No. 3581616 Japanese Patent No. 3898510 Japanese Patent No. 4052832 Japanese Patent No. 4113403 Japanese Patent No. 408137 Japanese Patent No. 3914206 Japanese Patent No. 4674096 Japanese Patent No. 4593302 Japanese Patent No. 4860163 Japanese Patent No. 3083535 Japanese Patent No. 4718926 Japanese Patent No. 4589810 Japanese Patent No. 4278374 Japanese Patent No. 4593302 Japanese Patent No. 4674119 Japanese Patent No. 5421982 Japanese Patent No. 6049461

The technical problems to be solved by the embodiments of the present invention have been made in view of the above-described problems, and the oxide film of the electrode can be easily penetrated to make a connection, and the resistance value of the initial connection is low. An object of the present invention is to provide a conductive particle, an anisotropic conductive material, and a connection structure which are not recovered and have a small increase in resistance even under high temperature/high humidity and which are excellent in reliability.

Conductive particles according to one embodiment of the present invention,
As inter-electrode particles for electrically connecting the electrodes contained between the electrodes, an oxide film is provided on the surface of at least one of the electrodes,
The conductive particles include an insulating core and a conductive layer provided on the surface of the core, or a conductive layer having a protrusion on the surface of the core,
When the conductive particles are compressed at 25° C. using a micro compression tester, the deformation rate of the conductive particles is x-axis and x-axis, and the elastic portion ratio of the indenting process defined as [1] below is the y-axis. In the graph plotted in
Section (a) in which the proportion of the elastic part of the indentation is kept constant after the first discontinuity, and the proportion of the elastic part of the indentation (x) is constant after the second discontinuity. The oxide film is penetrated or destroyed by the conductive layer or the conductive layer having the protrusions within the range of the elastic portion ratio and the deformation rate of the indentation process of the conductive particles between the section (b) kept at. Characterize.

The average deformation amount c (that is, the slope) of the elastic portion ratio of the indenting process according to the deformation rate in the interval after the interval b is −1≦c≦4, and the elasticity of the indentation operation is in the interval after the interval b. The part ratio is smaller than the elastic part ratio of the maximum indentation between the sections a and b.

Then, the oxide film can penetrate or break when the deformation rate of the conductive particles is in the range of 17.4 to 70.0%.

The surface of the insulating core may be an activation-treated surface.

The activation-treated surface may be a surface treated by a treatment selected from the group consisting of ozone treatment, electron beam treatment, plasma treatment and corona treatment.

The insulating core may be plated with the conductive layer under a catalyst attached to the activation surface.

The insulating core may be resin particles or hybrid particles.

The resin fine particles are monomers selected from urethane series, styrene series, acrylate series, benzene series, epoxy series, amine series, imide series, or modified monomers thereof, or copolymers of these mixed monomers. Good.

The hybrid particles may be particles having a structure of an organic core and an inorganic shell surrounding the organic core, or particles having a structure of an inorganic core and an organic shell surrounding the inorganic core.

The organic core or the organic shell is provided by a monomer selected from urethane series, styrene series, acrylate series, benzene series, epoxy series, amine series and imide series, or a modified monomer thereof, or a mixed monomer of the above monomers. Can be done.

And, the inorganic core or the inorganic shell may be provided from an oxide, nitride or carbide of a metal selected from Si, Ti, Al, Zr, Ba and W.

An insulating layer or insulating particles may be further included on the conductive layer.

The conductive particles may be further subjected to a rust preventive treatment on the outermost surface of the conductive particles.

An anisotropic conductive material according to another aspect of the present invention is an anisotropic conductive material containing the conductive particles.

An anisotropic conductive material according to another aspect of the present invention is a connection structure containing the conductive particles.

An anisotropic conductive material according to another aspect of the present invention is an electric/electronic component including the conductive particles.

The conductive particles according to the embodiment of the present invention have low initial electrical resistance, and can be used to manufacture an anisotropic conductive material and a connection structure having a low resistance increase after a high temperature/high humidity reliability test.

That is, the conductive particles according to the embodiment of the present invention are designed such that the conductive particles are designed in consideration of the time when the oxide film is destroyed and the curing degree of the resin as the anisotropic conductive material, and the initial electric resistance is low and the connection reliability is high. It has the effect of enhancing sex.

FIG. 1 is a graph for explaining the concept of the elastic portion ratio of indentation processing. FIG. 2 is a graph of nIT values according to changes in the deformation rate of conductive particles.

DETAILED DESCRIPTION OF THE INVENTION Before describing the present invention in detail below, the terms used herein are for the purpose of describing particular embodiments only, and the scope of the present invention as defined only by the claims. Is not intended to be limiting. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art, unless specified otherwise.

Throughout the specification and claims, unless otherwise specified, the words "comprising", "comprising" include the listed articles, steps or constructions of articles, steps, or groups of constructions and steps. It is not meant to exclude any other building, step, or group of building, and steps, arbitrarily.

On the other hand, various embodiments of the invention may be combined with any other embodiment, unless there is a clear correspondence. Any feature specifically or indicated as advantageous may be combined with any other feature or features indicated as preferred or advantageous.

The elastic part ratio of indentation described in the following specification is defined as the elastic part ratio value (nIT) of indentation according to the deformation rate of the conductive particles as follows:

(Welastic: Indentation work of elastic part, Wplastic: Indentation of plastic part, nIT: Elastic part ratio value of indentation)

FIG. 1 is a graph for explaining the concept of the elastic portion ratio of indentation processing. The elastic portion ratio (nIT) of the indentation process can be measured using a micro compression tester (MCT). The nIT value can be obtained by changing the applied load and measuring the amount of deformation of the particles. At this time, the maximum movement distance (hmax) of the indentor is used as the deformation amount. For example, in the case of Example 3, when the conductive particles were measured at 5 mN, the maximum moving distance of the indenter was 1.397 μm, the deformation rate of the conductive particles was 43.0%, and Wt was 2.593 nJ. Yes, We is 0.896 nJ and nIT is 34.6%. Therefore, the nIT value according to the measurement rate can be obtained by gradually increasing the measured load.

The nIT value is measured using a micro compression tester (FISHERSCOPE HM2000) and a plane indenter having a side length of 50 m. The measurement conditions of the nIT value according to the deformation rate of the conductive particles are as follows: the indenter descending speed at 25° C. is 0.33 mN/sec, and the ascending speed is 0.1 mN at 10 sec. At this time, the amount of deformation of the particles is measured by the maximum moving distance (hmax) of the indenter.

Hereinafter, the present invention will be described in more detail with reference to Examples.

The conductive particles according to the embodiment of the present invention are conductive particles that are interposed between the electrodes and electrically connect the electrodes, and an oxide film is provided on the surface of at least one of the electrodes. The conductive particles include an insulating core and a conductive layer provided on the surface of the core.

FIG. 1 is a graph showing the results of compressing conductive particles according to an embodiment of the present invention at 25° C. using a micro compression tester (FISHERSCOPE HM2000). At this time, the deformation rate of the conductive particles is taken as the x-axis, and the elastic portion ratio of the indentation obtained by the above equation (1) is taken as the y-axis.

According to this, the graph has two discontinuities, namely the first discontinuity and the second discontinuity, and after each discontinuity the two intervals in which nIT remains constant. .. The period during which nIT is kept constant after the first discontinuity is called interval a, and the period during which nIT is kept constant after the second discontinuity is called interval b. The first discontinuity is the fulcrum at which the conductive layer of the conductive particles is destroyed, and the second discontinuity is the fulcrum at which the insulating core is destroyed. At this time, although it is constant for convenience of explanation, it may be slightly different in an actual experiment.

At this time, the oxide film of the electrode is broken between the space a and the space b. That is, the conductive layer of the conductive particles or the conductive layer having the protrusions, which is in contact with the electrode of the chip and the electrode of the substrate, should not penetrate through the oxide film after the interval a at which the destruction of the conductive layer occurs. If the oxide film penetrates before the conductive layer is destroyed, the hardness of the conductive particles is too strong, so the connection is made in a state where the deformation of the conductive particles is small and the connection reliability becomes weak. With 60% to 80% of the deformation, it becomes impossible to meet the design specifications of the electronic product that makes the electrical connection.

Therefore, after the conductive layer is destroyed, the conductive particles can penetrate the oxide film of the electrode by the conductive layer or the protruding conductive layer in a state where the elastic portion ratio of the indenting process increases in accordance with the increase in the deformation rate. It must be designed so that it can exert force.

At this time, the deformation rate of the conductive particles at the time when the oxide film is broken is 17.4 to 70.0%, preferably 24.6 to 67.1%, more preferably 30.0 to 65.0%, and further It is preferably 50.0 to 60.3%.

When the conductive particles according to the exemplary embodiment of the present invention are used as an electrical connecting material for an anisotropic conductive material, the anisotropic conductive film is placed between electrodes to be bonded, The method of curing the resin under heat/pressure and connecting the upper and lower electrodes with conductive particles is used.

By curing the resin of the anisotropic conductive material, the conductive particles inside are fixed together, the electrical connection state is maintained as it is, and the connection stability is secured.

At this time, the curing reaction of 75 to 95% of the anisotropic conductive film resin is performed under heating/pressurizing conditions, and the remaining 5 to 25% is performed after releasing the heating/pressurizing conditions. In this way, if the elastic part ratio of the indentation process of the conductive particles after releasing the heating/pressurizing condition is large, the gap between the upper and lower electrodes and the anisotropic conductive material that has not been completely cured may be borliged. And acts as a cause for greatly increasing the connection resistance thereafter.

Therefore, the conductive particles according to the embodiment of the present invention are designed so that the increase in the elastic portion ratio (nIT) of the indentation processing due to the strain beyond the section b is extremely limited. That is, the average deformation amount c (that is, the slope) of the elastic portion ratio of the indentation processing in accordance with the change in the deformation rate in the section after the section b is −1≦c≦4, preferably −0.5≦c≦3. 0 is preferable, -0.3≤c≤2.5 is more preferable, and -0.2≤c≤2.0 is further preferable. Further, the elastic portion of the indentation works in the section after the section b, and the maximum elastic portion of the indentation becomes small in the section between the section a and the section b.

In this case, in the sections a and b, the elastic portion of the indentation process is high, so that it is suitable for penetrating the oxide film, and since the deformation rate of the elastic portion of the indentation process after the section b is low, it is preferable. is there. Even before the anisotropic conductive film resin is completely cured, the elasticity of the conductive particles is high, so that the connection does not become unstable.

The insulating core of the conductive particles is not particularly limited. For example, resin fine particles or organic/inorganic hybrid particles may be used.

The resin fine particles can be prepared using urethane-based, styrene-based, acrylate-based, benzene-based, epoxy-based, amine-based, imide-based monomers, modified monomers thereof, or mixed monomers thereof. They can be polymerized by seed polymerization, dispersion polymerization, suspension polymerization, emulsion polymerization and the like.

The organic/inorganic hybrid particles have a core-shell structure in which the shell is an inorganic material when the core is an organic material and the shell is an organic material when the core is an inorganic material. As the organic material, the above-mentioned monomers, modified monomers thereof, or mixed monomers can be used. As the inorganic material, oxides such as SiO ₂ , TiO ₂ , Al ₂ O ₃ and ZrO ₂ ; nitrides such as —AlN, Si ₃ N ₄ , TiN and BaN −; and carbides such as WC, TiC and SiC are used. be able to.

The shell can be formed by a chemical coating method, a sol-gel method, a spray coating method, a CVD (chemical vapor deposition) method, a PVD (physical vapor deposition) method, a plating method, or the like. The particles can also be of the type in which the inorganic particles are dispersed in the organic matrix, or of the type in which the organic particles are dispersed in the inorganic matrix, or of the type in which the ratio of organic particles to inorganic particles is 50:50. ..

The material of the conductive layer of the conductive particles is not particularly limited. Common metals, for example, single metals such as gold, silver, nickel, copper, tin, zinc, titanium, and binary alloys such as tin-lead, tin-copper, tin-zinc, nickel-phosphorus, nickel- Three or more alloys such as boron and nickel-tungsten, copper-zinc-tin, nickel-phosphorus-tungsten, nickel-boron-tungsten and nickel-phosphorus-cobalt can be used. Alternatively, a conductive layer of two or three kinds of alloys is formed on a single metal layer.

The thickness of the conductive layer of the conductive particles is preferably about 30 to 300 nm. If the conductive layer is thin, the resistance value becomes high. If the thickness of the conductive layer is too large, the conductive layer and the insulating core will peel off even if the conductive particles are slightly deformed under the pressure condition of heating/pressurizing with the anisotropic conductive material, and the product reliability will decrease. To do. The preferred thickness is 80-200 nm.

In some cases, the surface layer of the conductive layer of the conductive particles contains a noble metal such as gold, silver, platinum, or palladium. This is because the conductivity of the conductive particles is increased and the effect of preventing oxidation is also obtained. The method for forming the layer is not particularly limited. Conventionally known techniques such as a general sputtering method, a plating method, and a vapor deposition method can be used.

The material of the protrusions of the conductive particles is not particularly limited. When the conductive particles of the present invention are used as the anisotropic conductive material, it is sufficient that the conductive particles have a hardness sufficient to destroy the resin binder and the metal oxide film in the pressure bonding step.

The most effective material is metal. The metal is not particularly limited. For example, a single metal such as gold, silver, copper, nickel, titanium, tungsten, cobalt, bismuth, palladium or antimony, or two such as copper-zinc, copper-tin, nickel-phosphorus, nickel-tungsten or nickel. Alloys of three or more, such as copper-zinc-tin, nickel-phosphorus-tungsten, nickel-boron-tungsten, nickel-phosphorus-cobalt, nickel-phosphorus-palladium and nickel-boron-palladium. be able to.

The size of the protrusion is not particularly limited. A preferable size of the protrusion is a convex shape of 50 nm to 500 nm. If the size of the protrusion is too small or too large, the effect of destroying the metal oxide layer and the binder resin becomes weak. Therefore, the size of the protrusion is more preferably 100 to 300 nm.

The method for producing the conductive particles according to the embodiment of the present invention is not particularly limited. For example, a catalyst material can be applied to the surface of the insulating core, and the conductive layer and the protrusions can be formed by electroless plating. Small metal or inorganic particles can be attached to the insulating microparticles and electroless plating can be performed to form the conductive layers and protrusions.

Activating the core surface can be performed before applying the catalyst material. It is desirable to provide the catalytic material in contact with the activated surface.

The activation treatment is carried out in order to apply the catalytic material to the surface with improved adhesion. The activation treatment can be performed by ozone treatment, electron beam irradiation, or plasma or corona treatment. It is preferable to add ozone because it is easily applied during the reaction.

The ozone treatment can be carried out in an appropriate amount in consideration of the corrosiveness of the container, the apparatus and the piping and the shortening of the treatment time. The amount of ozone introduced can range from 10 to 50,000 ppm. It is preferably in the range of 50 to 25,000 ppm, more preferably in the range of 100 to 10,000 ppm, and within this range, the core surface can be sufficiently subjected to activation treatment.

The outermost layer of the conductive particles according to the exemplary embodiment of the present invention preferably has an insulating layer. With the miniaturization and high integration of electronic products, the pitch of electrodes becomes narrower, and when there are no insulating particles on the outermost periphery, electrical conduction is established between adjacent electrodes. As a method for forming the insulating layer, there are a method of chemically bonding the insulating particles and the outermost periphery of the conductive particles using a functional group, a method of dissolving an insulating solution in a solvent, and a method of applying by spraying or dipping. Can be mentioned.

The conductive particles of the conductive layer according to the embodiment of the present invention are preferably subjected to rust prevention treatment. This is because the anticorrosion treatment has an effect of increasing the contact angle with water to improve reliability in a high-humidity environment, and at the same time, reduces impurities' performance degradation of the connecting member by dissolving in water. Therefore, the anticorrosive agent preferably has hydrophobicity. The coating can be carried out by dissolving the anticorrosive agent in a solvent, followed by dipping, spraying and the like.

The particle size of the conductive particles is not particularly limited, but is preferably 5 μm or less, more preferably 4 μm or less. Since the anisotropic conductive material produced using the conductive particles of the present invention is used when the gap between the electrodes is extremely small, it is rare to use a distance of 5 Å or more.

The average diameter of the conductive particles is determined using the mode measured using a particle size analyzer (BECKMAN MULTISIZER™ 3). As an example, the number of conductive particles measured was 75,000.

The anisotropic conductive material can be manufactured by dispersing the conductive particles according to the embodiment of the present invention in a binder resin. Examples of the anisotropic conductive material include an anisotropic conductive paste, an anisotropic conductive film, and an anisotropic conductive sheet.

The resin binder is not particularly limited. For example, vinyl-based resins such as styrene-based, acrylic-based and vinyl acetate-based resins can be used. Thermoplastic resins such as polyolefins and polyamides. Curable resin such as urethane resin and epoxy resin. These resins may be used alone or in combination of two or more. A radical initiator such as BPO (Benzoyl Peroxide) or a photoinitiator such as TPO (Trimethylbenzoyl Phenylphosphinate) or an epoxy latent curing agent such as HX3941HP can be used alone or in combination for polymerizing or curing the resin. Further, other materials may be added to the binder resin for anisotropic conductive material within a range not achieving the object of the present invention. For example, colorants, softeners, heat stabilizers, light stabilizers, antioxidants, and inorganic particles.

The method for manufacturing the anisotropic conductive material according to the embodiment of the present invention is not particularly limited. For example, the conductive particles can be uniformly dispersed in a resin binder to be used as an anisotropic conductive paste, or can be spread thinly on a release paper and used as an anisotropic film.

The connection structure of the present invention connects the circuit boards to each other using the conductive particles according to the embodiment of the present invention or the anisotropic conductive material according to the embodiment of the present invention. For example, it can be used as a means for connecting a display semiconductor chip of a smartphone to a glass substrate forming a circuit, or connecting a μ-LED or a mini-LED to a circuit board. The connection structure of the present invention does not cause a circuit malfunction due to a circuit connection failure or a sudden increase in resistance.

Hereinafter, the present invention will be specifically disclosed with reference to Examples. The examples below are intended to illustrate the invention and are not intended to limit the invention thereto.

Example 1
1) Synthesis of insulating core
750 g of monomer TMPETA (Trimethylolpropane ethoxylate triacrylate), 40 g of HDEDA (1,6-Hexanediol ethoxylate diacrylate) and 750 g of DVB (Divinylbenzene) were added to a 3 L glass beaker, and 5 g of initiator BPO was added, and the mixture was added. Mixed. This was treated in a 40 kHz ultrasonic bath for 10 minutes to prepare a first solution.

A second solution was prepared by adding 500 g of dispersion stabilizer PVP-30K (Polyvinylpyrrolidone-30K) and surfactant Solusol (Dioctyl sulfosuccinate sodium salt) to 4,000 g of deionized water in a 5 L PP beaker. ..

The first and second solutions were placed in a 50 L reactor and 41,000 g deionized water was added. The solution was treated with an ultrasonic homogenizer (20 kHz, 600 W) for 90 minutes and heated to 85° C. while rotating the solution at 120 rpm. After the temperature of the solution reached 85° C., the polymerization process was performed for 16 hours.

The polymerized fine particles were filtered, washed, classified and dried to obtain resin fine particles as an insulating core. The average diameter of the insulating core was measured using the mode measured using a particle size analyzer (BECKMAN MULTISIZER TM3). The number of insulating cores measured was 75,000. The average diameter was 2.46 μm.

2) Particle plating process (1) Catalyst treatment process
25 g of the prepared insulating core was placed in a solution of 800 g of deionized water and 1 g of surfactant Triton X100, treated in an ultrasonic bath for 1 hour, washed and degreased to remove excess unreacted monomer and oiliness. The component was removed. At the end of the insulating core washing and degreasing step, the washing step was performed three times using deionized water at 40°C. After the water washing step, bubbling was performed for 1 hour using air having an ozone concentration of 200 ppm. Air bubbling was performed using an impeller on an overhead stirrer while stirring the solution at 200 rpm. After the ozone treatment, the cleaning process was performed only once.

Then Pd catalyst treatment. 150 g stannous chloride and 300 g 35-37% hydrochloric acid were dissolved in 600 g deionized water and charged with a washed and defatted insulating core, then sensitized by immersion and stirring for 30 minutes at 30°C. did. Wash 3 times with water.

To 600 g of deionized water, 1 g of palladium chloride and 200 g of 35-37% hydrochloric acid were added, and activation treatment was performed at 40° C. for 1 hour. After the activation treatment, a water washing step was performed 3 times.

The activated insulative core was placed in a solution of 100 g of 35-37% hydrochloric acid, and 600 g of deionized water and the mixture was stirred for 10 minutes at room temperature (accelerated treatment). After the accelerated treatment, it was washed three times with water to obtain a catalyst-treated insulating core material for electroless plating.

(2) Plating process
In a 5 L reactor, 3500 g deionized water, 260 g nickel sulphate as Ni salt, 5 g sodium acetate as complexing agent, 2 g lactic acid, 0.001 g Pb-acetate as stabilizer, 0. A plating solution was prepared by sequentially dissolving 001 g of sodium thiosulfate, 1 g of PEG-1200 as a surfactant, and 0.02 g of Triton X-100 (solution (a)). The catalyst-treated insulating core was put into the prepared solution (a) and dispersed using an ultrasonic homogenizer for 10 minutes. After the dispersion treatment, the pH of the solution (solution (b)) was adjusted to 5.5 with aqueous ammonia.

A solution (c) was prepared by dissolving 400 g of deionized water, 300 g of sodium hypophosphite as a reducing agent, and 0.0001 g of sodium thiosulfate as a stabilizer in a 1 L beaker. Solution (c) is introduced into the 5 L reactor (solution (b)) by a metering pump at a temperature of 55° C. in an amount of 10 g/min, and the temperature of the reactor is heated and 30 minutes until 70° C. is reached. Maintained.

After addition of the solution (c) was completed and maintained for 30 minutes, Ni-plated conductive particles were obtained. The size of the projections (insulating fine particles) of the produced conductive particles is obtained as follows using the FE-SEM photograph using the maximum point concentric circle (DH) and the lowermost point concentric circle (DL) on the outermost surface. be able to.

The size of the protrusions of the produced conductive particles was 112 nm.

Example 2
Insulating cores were synthesized using 1500 g HDEDA. The remaining steps were performed in the same manner as in Example 1, using the insulating core 24g prepared above. The average diameter of the produced insulating core was 2.53 μm. The size of the protrusions of the produced conductive particles was 86 nm.

Example 3
An insulating core was synthesized with 800 g of TMPETA, 50 g of HDEDA and 800 g of DVB. The remaining steps were carried out in the same manner as in Example 1 using 40 g of the insulator core manufactured as described above. The insulating core produced had an average diameter of 3.04 μm. The size of the protrusions of the produced conductive particles was 135 nm.

Example 4
An insulating core was synthesized using 1100 g of TMMT (Tetramethylol Methane Tetaacrylate) and 400 g of DVB. The remaining steps were performed in the same manner as in Example 1 using 25 g of the insulating core prepared above. The insulating core produced had an average diameter of 2.96 μm. The size of the protrusions of the produced conductive particles was 131 nm.

Example 5
An insulating core was synthesized using 800 g of MMA (Methylmethacrylate) and 800 g of DVB. Other than that was performed like Example 1 using 35 g of the insulator cores prepared above. The average diameter of the produced insulator core was 3.80 μm. The size of the protrusions of the produced conductive particles was 173 nm.

Example 6
An insulating core was synthesized using 1800 g HDEDA. Other than that was performed like Example 1 using 35 g of the insulator cores prepared above. The insulating core produced had an average diameter of 4.80 μm. The size of the protrusions of the produced conductive particles was 153 nm.

Example 7
The insulating core was synthesized using 1650 g HDEDA. The catalyst treatment of Example 1 was performed using 40 g of the prepared insulating core. Using the plating solutions (a), (b), and (c) under the same conditions as in Example 1, the solution temperature (b) was kept at 65° C., and the solution temperature (c) was 10 g/min. And added.

After addition of the solution (c) was completed and maintained for 30 minutes, Ni-plated conductive particles were obtained. The insulating core produced had an average diameter of 3.75 μm. The size of the protrusions of the produced conductive particles was 30 nm.

Example 8
An insulative core was synthesized using 1500 g styrene and 250 g DVB. The remaining steps were performed in the same manner as in Example 1 using 45 g of the insulating core prepared above. The insulating core produced had an average diameter of 3.81 μm. The size of the protrusions of the produced conductive particles was 164 nm.

Example 9
An insulating core was coated with the conductive particles of Example 3 above.
1) Manufacture of insulating core
A 250 ml flask was charged with 10 g of styrene, 3 g of BA (Butyl acrylate) and 150 g of deionized water and mixed. To this mixture, 2.0 g of PVP-30K and 0.3 g of potassium peroxodisulfate (Potassium peroxodisulfate) were added, and the mixture was stirred at 70° C. for 10 hours. Next, 3.0 g of EGDMA (Ethylene glycol dimethylacrylate), 0.5 g of PVA-150 (MW 8,000-Polyvinyl Alchol) and 30 g of deionized water were added to this reaction solution, and the mixture was further stirred at 70° C. for 12 hours. Hexamethylenediamine (3.0 g) was further added to the reaction mixture, and the mixture was stirred at 50° C. for 24 hours to obtain an insulating core having an average particle size of 150 nm. The insulating core was confirmed by SEM and the average diameter was determined by measuring 10 particles.

2) Coating of insulating fine particles
The prepared insulating core was washed, filtered, and then put into a methyl alcohol solvent to prepare a dispersion liquid having a solid content of 5%. 500 g of methanol, 20 g of the above dispersion and 10 g of the conductive particles of Example 3 were added to a 1 L beaker, the mixture was sonicated in a 50° C. ultrasonic bath for 30 minutes and stirred for 10 hours. A conductive particle coated with insulating fine particles is prepared.

Example 10
500 g of deionized water was added to 20 g of SG-1 (trade name: manufactured by MSC), and the temperature of the solution was kept at 60°C. 10 g of conductive particles prepared in Example 3 were added. The solution was kept at 60° C. and sonicated for 5 minutes. The ultrasonically treated conductive particles were washed, filtered, and dried to obtain anticorrosive conductive particles. When the dried anticorrosive conductive particles were poured into pure water, it was confirmed that the weight ratio of the conductive particles floating in the pure water was 98% or more, and anticorrosion treatment was performed.

Comparative example 1
An insulating core was synthesized with 1600 g MMA and 250 g DVB. In the same manner as in Example 1 except that ozone treatment was performed, steps other than using the prepared insulating core 40g were performed. The insulating core produced had an average diameter of 4.71 μm. The size of the protrusions of the produced conductive particles was 184 nm.

Comparative example 2
An insulating core was synthesized using 1450 g of MMA (Methylmethacrylate) and 200 g of DVB. The remaining steps were performed in the same manner as in Example 1 using the prepared insulating core 45g. The prepared insulating core had an average diameter of 3.00 μm. The size of the protrusions of the produced conductive particles was 162 nm.

Experimental Example The conductive particles obtained in Examples 1 to 10 and Comparative Examples 1 and 2 were evaluated.
1) Measurement of conductive particle size The average particle diameter of the conductive particles is determined using the mode value measured using a Particle Size Analyzer (BECKMAN MULTISIZER TM3). The number of conductive particles measured was 75,000.

2) Measurement of nIT and amount of deformation The amount of nIT and the amount of deformation were measured with a micro compression tester (FISHERSCOPE HM2000) using a flat indenter (Indenter) having a side length of 50 μm. The nIT and the amount of deformation were measured for a total of 5 conductive particles and averaged. The measurement conditions were as follows: the indenter descending amount at 25° C. was 0.33 mN/sec, and the ascending amount was 0.1 mN at 10 sec. NIT and the amount of deformation were measured by taking the values of nIT and Hmax (maximum indenter depth) using software in the micro compression tester (software WinHCU5.1; operation analysis software of the micro compression tester).

3) Measurement of connection resistance (1) Production of anisotropic conductive film Naphthalene-based epoxy resin HP4032D (manufactured by DIC, trade name) 2 g and phenoxy resin YP-50 (manufactured by Toto Kasei Co., trade name) 20 g and acrylic epoxy resin VR-60 (Showa Denko KK, trade name) 25 g, thermosetting agent HXA-3922HP (Asahi Kasei KK, trade name) 22 g, epoxy silane coupling agent A-187 (Momentive Co., trade name) 5 g were well mixed. Then, a solvent 50% solids formulation was made using toluene. The conductive particles were added in an amount of 10% by weight of the mixture, and then mixed for 5 minutes using a planetary mixer at a revolution of 400 rpm and a rotation of 150 rpm to prepare an anisotropic conductive paste. A film having a thickness of 20 μm was formed on a release film using the anisotropic conductive paste, and then dried in the atmosphere using a hot air drying oven at 75° C. for 5 minutes to give a final thickness difference of 12 μm. An anisotropic conductive film was made.

(2) Electrode for resistance measurement The electrode for resistance measurement is a glass substrate on which a transparent electrode is formed by depositing ITO (Indium Tin Oxide) on a glass substrate and an FPCB with an electrode width of 20 μm and an electrode interval of 50 μm. I prepared. The pattern of electrodes was coated with Al against Au base.

(3) Bonding
After cutting the anisotropic conductive film with a width of 3 mm and using a bonding jig with a width of 1 mm and a length of 3 mm, a free substrate having ITO was pressure-bonded at 0.2 MPa, 120° C. for 10 seconds, The FPCB was placed, and bonding was performed at 40 MPa, 200° C. for 20 seconds to produce a connection structure.

(4) Measurement of initial connection resistance The resistance value was measured using the FPCB electrode of the connection structure. Resistance was measured using an ADCMT 6871E Digital Multimeter 2 probe.

(5) Measurement of reliability resistance The resistance of reliability was measured after leaving it under the condition of 85°C/85% humidity for 100 hours. Resistance was measured using an ADCMT 6871E Digital Multimeter 2 probe.

The standard of initial connection resistance is as follows.
○○○: 2Ω or less ○○: Over 2Ω to 3Ω or less
○: Over 3Ω ~ 5Ω or less
×: Over 5Ω

The standard for increasing the connection resistance after a reliability test at 85°C/85% for 100 hours is as follows.
○○○: Increase of 2Ω or less ○○: Increase of more than 2Ω to 4Ω or less
○: Increase of more than 4Ω to less than 6Ω
×: Over 6Ω~ rise

Table 1 shows the elastic portion ratio of the indentation processing according to the deformation rate of each embodiment.

Further, in Table 2, the initial resistance and the 85/85 test of the above-described examples and comparative examples were performed to measure the resistance value.

As a result of comparing Examples 1 to 10 and Comparative Examples 1 to 2 of Tables 1 and 2 and the related FIGS. 1 and 2, the deformation rate of the conductive particles at the time of oxide film destruction was 17.4 to 70%. Preferably, the average deformation amount c (that is, the inclination) of the elastic portion ratio of the indentation processing according to the deformation rate of the section that has passed the section b is designed to be −1≦c≦4.

The features, structures, effects, and the like shown in the above-described embodiments can be combined and modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the invention is not limited to these combinations and modifications.

Claims (16)

As inter-electrode particles for electrically connecting the electrodes contained between the electrodes, an oxide film is provided on the surface of at least one of the electrodes,
The conductive particles include an insulating core and a conductive layer provided on the surface of the core, or a conductive layer having a protrusion on the surface of the core,
Plot when the deformation rate of the conductive particles when compressed with a micro compression tester at 25°C is the x-axis, and the elastic portion ratio of the indenting process defined as [1] below is the y-axis. In the graph
Section (a) in which the elastic portion ratio of indentation is kept constant after the first discontinuity point, and section (b) in which the elastic portion ratio of x indentation is kept constant after the second discontinuity point. The conductive particles are characterized in that the oxide film is penetrated or destroyed by the conductive layer or the conductive layer having the protrusions within the range of the elastic portion ratio and the deformation rate of the indentation processing of the conductive particles.
The average deformation amount c (that is, the slope) of the elastic portion ratio of the indenting process according to the deformation rate in the interval b after the interval b is −1≦c≦4, and the elasticity of the indentation operation is in the interval after the interval b. The conductive particle according to claim 1, wherein the part ratio is smaller than the elastic part ratio of the maximum indentation processing between the section a and the section b. The conductive particles according to claim 1, wherein the oxide film penetrates or is destroyed in a deformation ratio of the conductive particles in the range of 17.4 to 70%. The conductive particle according to claim 1, wherein the surface of the insulating core is an activated surface. The conductive particles according to claim 4, wherein the activated surface is a surface treated by a treatment selected from the group consisting of ozone treatment, electron beam treatment, plasma treatment and corona treatment. The conductive particles according to claim 4, wherein the insulating core is formed by plating the conductive layer under a catalyst attached to the activation-treated surface. The conductive particles according to claim 6, wherein the insulating core is resin fine particles or hybrid particles. The resin fine particles are provided from a monomer selected from urethane series, styrene series, acrylate series, benzene series, epoxy series, amine series and imide series, or a modified monomer thereof, or a mixed monomer of monomers. Item 7. The conductive particles according to Item 7. The conductive particles according to claim 7, wherein the hybrid particles are particles having a structure of an organic core and an inorganic shell surrounding the organic core, or particles having a structure of an inorganic core and an organic shell surrounding the inorganic core. The organic core or shell is provided by a monomer selected from urethane series, styrene series, acrylate series, benzene series, epoxy series, amine series and imide series, or a modified monomer thereof, or a mixed monomer of monomers. The conductive particles according to claim 9, wherein The conductive particle according to claim 9, wherein the inorganic core or the inorganic shell is provided from an oxide, nitride or carbide of a metal selected from Si, Ti, Al, Zr, Ba and W. The conductive particle according to claim 1, further comprising an insulating layer or insulating particles on the conductive layer. The conductive particles according to claim 1, wherein the outermost surface of the conductive particles is subjected to rust prevention treatment. An anisotropic conductive material containing the conductive particles according to claim 1. A connection structure containing the conductive particles according to claim 1. An electric/electronic component including the conductive particles according to claim 1.