Patent Application
20240266086
The present technology relates to a composite conductive particle in which a metal film is formed on a particle surface and a method for manufacturing a composite conductive particle. This application claims priority based on Japanese Patent Application No. 2020-129750 filed on Jul. 30, 2020, in Japan, which is incorporated by reference in this application.
A technique is known in which small particles are made to physically collide with a surface of a host particle by a mechanochemical method to form a film with the small particles on the surfaces of the host particle (see, e.g., Patent Document 1).
The present technology was proposed in view of such conventional circumstances, and provides a composite conductive particle that is able to suppress cracking and peeling of metal films to provide excellent adhesion of metal films, and a method for manufacturing a composite conductive particle.
A composite conductive particle according to the present technology includes: a host particle; and an adhesive fine particle arranged on a surface of the host particle and containing oxygen atoms; and a conductive fine particle in contact with the adhesive fine particle.
A method for manufacturing a composite conductive particle according to the present technology includes: mixing host particles, adhesive fine particles containing oxygen atoms, and conductive fine particles by a mechanochemical method; arranging the adhesive fine particles on the surface of the host particles; and bringing the conductive fine particles into contact with the adhesive fine particles.
A method for manufacturing a composite conductive particle according to the present technology includes: mixing host particles and adhesive fine particles containing oxygen atoms by a mechanochemical method; subsequently mixing conductive fine particles by a mechanochemical method; arranging the adhesive fine particles on the surface of the host particles; and bringing the conductive fine particles into contact with the adhesive fine particles.
The present technology arranges the adhesive fine particles containing oxygen atoms on the surface of the host particle and brings the conductive fine particles into contact with the adhesive fine particles, thereby achieving excellent adhesion of the metal film.
Embodiments of the present invention will be described in detail in the following order with reference to the drawings.
The composite conductive particle according to the present embodiment includes a host particle, an adhesive fine particle arranged on the surface of the host particle and containing oxygen atoms, and a conductive fine particle in contact with the adhesive fine particle. By arranging the adhesive fine particle containing oxygen atoms on the surface of the host particle and bringing the conductive fine particle into contact with the adhesive fine particle, it is possible to achieve excellent adhesion of the metal film.
Here, “the state in which the adhesive fine particle is arranged on the surface of the host particle” includes at least the state in which the adhesive fine particle is in direct contact with the surface of the host particle. In addition, “the state in which the conductive fine particle is in contact with the adhesive fine particle” includes at least the state in which the conductive fine particle is in direct contact with the adhesive fine particle. Such a state can be confirmed, e.g., by observing cross sections of the composite conductive particle by using a field-emission scanning electron microscope (FE-TEM/EDS).
Examples of the host particle 11 may include a resin particle, resin core conductive particle, organic-inorganic hybrid particle, and metal particle. Examples of resins constituting the resin particle include styrene-divinylbenzene copolymers, benzoguanamine resins, cross-linked polystyrene resins, acrylic resins, and styrene-silica composite resins. The resin core conductive particles are those in which a metal plating layer is provided on the surface of the aforementioned resin particles, and the metal plating layer is preferably a single metal or alloy of at least one of nickel, silver, copper, gold, and palladium. The thickness of the metal plating layer is preferably 50 to 300 nm, more preferably 80 to 250 nm. When the metal plating layer is composed of multiple metal layers, it is preferable that the total thickness satisfies the above range. The organic-inorganic hybrid particles include, e.g., particles formed by crosslinked alkoxysilyl polymers and acrylic resins. Examples of metal particles include nickel, cobalt, silver, copper, gold, palladium, and solder. Among these, it is preferable to use resin particles or resin core conductive particles having excellent stress relaxation properties.
The average particle size of the host particle 11 is preferably 3 to 300 μm, more preferably 10 to 50 μm. With this range, a good metal film can be formed by using a mechanochemical method. The particle size of the conductive particles may be measured by an image type particle size distribution meter (for example, FPIA-3000: manufactured by Malvern). The number of the particles is 1,000 or more, preferably 2,000 or more.
Examples of the adhesive fine particles 12 include organic polymer particles having oxygen atoms, organic fine particles containing organic monomer particles, and inorganic fine particles. Organic fine particles are not particularly limited as long as they have oxygen atoms and may include, e.g., (meth) acrylate compounds and epoxy compounds. Here, the (meth) acrylate compound includes an acrylate and a methacrylate and may be a polymer or a monomer. Epoxy compounds may include prepolymers and resins formed by curing the prepolymers.
In addition, resin particles having carboxyl groups are preferably used to impart a flux function to the composite conductive particles 10. Examples of resin particles having carboxyl groups include bisphenol AO,O-diacetic acid. This can remove oxide film and dirt from the surface of the electrode. In addition, when using solder fine particles such as SnBi and SnAgCu are used as conductive fine particles 13, not only the oxide film and dirt on the electrode surface mentioned above but also the oxide film and dirt on the melted solder surface can be removed.
The average particle size of the adhesive fine particles 12 is preferably 1/10 to 1/100,000 of the average particle size of the host particles 11, and more preferably 1/100 to 1/10,000. Thus, a metal film can be formed by the conductive fine particles 13.
The conductive fine particles 13 include single-composition metal particles such as Au, Ag, Cu, and Ni, as well as composite metal particles such as SnBi and SnAgCu. The present technology, using adhesive fine particles having oxygen atoms, can thicken the metal film not only with soft metals such as SnBi and SnAgCu but also with hard metals such as Cu and Ni, which have been difficult to be thickened in conventional methods.
As with the adhesive fine particles 12, the average particle size of the conductive fine particles 13 is preferably 1/10 to 1/100,000 of the average particle size of the host particles 11, and more preferably 1/100 to 1/10,000. Thus, a metal film can be formed by the conductive fine particles 13.
The composite conductive layer 14, which is a metal film arranged on the surface of the host particle 11, is formed by a mixture of adhesive fine particles 12 containing oxygen atoms and conductive fine particles 13 contacting the adhesive fine particles 12. In addition, the composite conductive layer 14 also includes a part where the adhesive fine particles 12 directly contact the surface of the host particle 11 and a part where the conductive fine particles 13 directly contact the surface of the host particle 11. In other words, in the composite conductive layer 14, the adhesive fine particles 12 cover a part of the surface of the host particle 11. This can achieve excellent adhesion of the composite conductive layer 14.
The adhesive layer 24 is formed from adhesive fine particles 22, and the adhesive fine particles 12 are in direct contact with almost all of the surfaces of the host particle 11. That is, in the adhesive layer 24, the adhesive fine particles 22 cover almost the entire surface of the host particle 21.
The conductive layer 25 is a metal film formed from conductive fine particles 23, and the conductive fine particles 23 are in direct contact with almost the entire surface of the adhesive layer 24. Since the adhesive fine particles 22 cover almost the entire surface of the host particle 21, superior adhesion of the conductive layer 25 can be obtained compared with the conventional conductive particles lacking the adhesive layer 24.
A method for manufacturing a composite conductive particle according to a first embodiment includes mixing host particles, adhesive fine particles containing oxygen atoms, and a conductive fine particles by a mechanochemical method, arranging the adhesive fine particles on the surface of the host particles, and bringing the conductive fine particle into contact with the adhesive fine particles. This can achieve excellent adhesion of the metal film.
Here, the mechanochemical method is a method that utilizes chemical reactions generated by mechanical energy applied to a substance in mechanical operations such as collision, compression, grinding, mixing, and kneading; examples of the mechanochemical method may include mixing methods using a high-speed agitation type powder spheroidizing device or a hybridizer, among others.
As shown in
The blending ratio of the adhesive fine particles 12 to the conductive fine particles 13 (mass of adhesive fine particles:mass of conductive fine particles) is preferably 0.001:1 to 0.3:1, more preferably 0.01:1 to 0.2:1, and still more preferably 0.05:1 to 0.15:1. Thus, as shown in
Furthermore, a method for manufacturing the composite conductive particles according to the second embodiment includes mixing host particles and adhesive fine particles containing oxygen atoms by a mechanochemical method, subsequently mixing conductive fine particles by a mechanochemical method, arranging the adhesive fine particles on the surface of the host particles, and bringing the conductive fine particles into contact with the adhesive fine particles. This can achieve excellent adhesion of the metal film.
As shown in
Here, the blending ratio of the adhesive fine particles 22 to the conductive fine particles 23 (mass of the adhesive fine particles:mass of the conductive fine particles) is preferably 0.001:1 to 0.3:1, more preferably 0.01:1 to 0.2:1, and still more preferably 0.05:1 to 0.15:1 as with the method for manufacturing a composite conductive particle according to the first embodiment. Thus, as shown in
Examples of the present technology will be described below. In the examples, composite conductive particles with a metal film formed on the surface of the particles were prepared by a mechanochemical method. Then, connection structures were fabricated by using the conductive films containing composite conductive particles, and the conduction characteristics thereof were evaluated. It should be noted that the present technology is not limited to these examples.
A conductive adhesive composition was prepared by introducing 5 parts by mass of a mixture containing composite conductive particles and 95 parts by mass of an insulating binder composed of the following components into a planetary agitator and stirring them for 1 minute. Then, the conductive adhesive composition was applied on a PET film, dried in an oven at 80° C. for 5 minutes to form an adhesive layer composed of the conductive adhesive composition on the PET film, thereby preparing a conductive film having a width of 2.0 mm and a thickness of 25 μm.
The insulating binder was prepared by mixing 47 parts by mass of phenoxy resin (product name: YP-50, manufactured by NSCC Epoxy Manufacturing), 3 parts by mass of monofunctional monomer (product name: M-5300, manufactured by TOAGOSEI), 25 parts by mass of urethane resin (product name: UR-1400, manufactured by Toyobo), 15 parts by mass of rubber component (product name: SG80H, manufactured by Nagase ChemteX), 2 parts by mass of silane coupling agent (product name: A-187, manufactured by Momentive Performance Materials Japan), and 3 parts by mass of organic peroxide (product name: NiperBW, manufactured by Nichiyu Corporation), into a mixed solution of ethyl acetate and toluene so that the solid content was 50% by mass.
A connection structure was prepared by thermocompression-bonding, via an anisotropic conductive film, an evaluation substrate (glass epoxy substrate (FR4), 200 μm pitch, line:space=1:1, terminal thickness 10 μm, Cu (undercoat)/Ni/Au plating) and an FPC (polyimide film, 200 μm pitch, line:space=1:1, terminal thickness 12 μm, Cu (undercoat)/Ni/Au plating). Thermo-compression bonding was carried out by pressing down the tool from the FPC side through a silicone rubber having a thickness of 200 μm under the conditions of a temperature of 150° C., a pressure of 2 MPa, and a time of 20 second.
The conduction resistance value of the connection structure was measured with four-terminal sensing using a digital multimeter (manufactured by Yokogawa Electric Corporation) by flowing a current of 1 mA. In addition, after an environmental test at a temperature of 85° C., a humidity of 85%, and a duration of 500 hours, the conduction resistance values of the connected structures were measured. The connection structures in which the conduction resistance value was 500 mΩ or less were evaluated as “AA”, the connection structures in which the conduction resistance value is more than 500 mΩ and 102 or less were evaluated as “A”, the connection structures in which the conduction resistance value is more than 102 were evaluated as “B”, and the connection structures in which the conduction resistance value was OPEN were evaluated as “C”.
Cracking and peeling of the metal film was evaluated by performing cross-sectional observation of composite conductive particles in the terminal part of the connection structure. Those in which there were no cracks in the metal film of the composite conductive particles in the terminal part were evaluated as “A”, those in which there were cracks in the metal film in less than half of the composite conductive particles in the terminal part were evaluated as “B”, and those in which there were cracks in the metal film in half or more of the composite conductive particles in the terminal part were evaluated as “C”.
In addition, those in which there were no peeling off of the metal film of the composite conductive particles in the terminal part were evaluated as “A”, those in which there were peeling off of the metal film in less than half of the composite conductive particles in the terminal part were evaluated as “B”, and those in which there were peeling off of the metal film in half or more of the composite conductive particles in the terminal part were evaluated as “C”.
Acrylic resin core Ni-plated particles (20 μm in diameter), Cu particles (100 nm in diameter), and MMA (methyl methacrylate, approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
After measuring 8 parts by mass of adhesive fine particles with respect to 100 parts by mass of conductive fine particles, the host particles, conductive fine particles, and adhesive fine particles were placed in a cup and mixed with a wood bar for 1 minute. This was fed into a high-speed agitation type powder spheroidizer (NSM-200, SEISHIN ENTERPRISE), and the granulation was carried out at 3,000 rpm for 1 min under nitrogen atmosphere to produce composite conductive particles.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles in Example 1 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Composite conductive particles were prepared in the same manner as in Example 1, except that acrylic resin core Ni-plated particles (20 μm in diameter), Ni particles (100 nm in diameter), and MMA (methyl methacrylate, approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles in Example 2 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Composite conductive particles were prepared in the same manner as in Example 1, except that acrylic resin core Ni-plated particles (20 μm in diameter), Cu particles (100 nm in diameter), and bisphenol AO,O-diacetic acid (approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles in Example 3 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Composite conductive particles were prepared in the same manner as in Example 1, except that acrylic resin core Ni-plated particles (20 μm in diameter), Cu particles (100 nm in diameter), and silica (SiO2, approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles in Example 4 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Composite conductive particles were prepared in the same manner as in Example 1, except that acrylic resin particles (20 μm in diameter), Cu particles (100 nm in diameter), and MMA (methyl methacrylate, approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles in Example 5 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Acrylic resin particles (20 μm in diameter), Cu particles (100 nm in diameter), and MMA (methyl methacrylate, approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
After measuring 11 parts by mass of adhesive fine particles with respect to 100 parts by mass of conductive fine particles, the host particles and adhesive fine particles were placed in a cup and mixed with a wood bar for 1 minute. This was fed into a high-speed agitation type powder spheroidizer (NSM-200, SEISHIN ENTERPRISE), and the granulation was carried out at 3,000 rpm for 1 min under nitrogen atmosphere.
The granulated particles and conductive fine particles were then placed in a cup and mixed with a wood bar for 1 minute. This was fed into a high-speed agitation type powder spheroidizer (NSM-200, SEISHIN ENTERPRISE), and the granulation was carried out at 3,000 rpm for 1 min under nitrogen atmosphere to produce composite conductive particles.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles of Example 6 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “B” and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Composite conductive particles were prepared in the same manner as in Example 1, except that acrylic resin core Ni-plated particles (20 μm in diameter), SnBi particles (100 nm in diameter), and bisphenol AO,O-diacetic acid (approximately 100 nm in diameter) were prepared as host particles, conductive fine particles, and adhesive fine particles, respectively.
The evaluation results of the connection structure prepared by using the conductive film containing the composite conductive particles of Example 7 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “AA”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
Acrylic resin core Ni-plated particles (20 μm in diameter) and Cu particles (100 nm in diameter) were prepared as host particles and conductive particles, respectively.
The host particle and conductive fine particles were placed in a cup and mixed with a wood bar for 1 minute. This was fed into a high-speed agitation type powder spheroidizer (NSM-200, SEISHIN ENTERPRISE), and the granulation was carried out at 3,000 rpm for 1 min under nitrogen atmosphere to produce composite conductive particles.
The evaluation results of the connection structure prepared by using the conductive film containing the composite conductive particles of Comparative Example 1 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “B”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “C”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “C”.
Composite conductive particles were prepared in the same manner as in Comparative Example 1, except that acrylic resin core Ni-plated particles (20 μm in diameter) and SnBi particles (100 nm in diameter) were prepared as host particles and conductive fine particles, respectively.
The evaluation results of the connection structure prepared by using the conductive film containing composite conductive particles in Reference Example 1 are shown in Table 1. The initial conductivity was evaluated as “AA” and the conduction reliability after the environmental test was evaluated as “A”. Also, the cracking of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”, and the peeling of the metal film of the composite conductive particles in the terminal part of the connection structure was evaluated as “A”.
When a metal film of high-hardness metal was formed directly on the surface of the host particle, as in Comparative Example 1, cracking and peeling of the metal film occurred, which degraded the evaluation of conduction reliability after the environmental test. In contrast, when adhesive fine particles containing oxygen atoms were placed on the surface of the host particles and a metal film containing conductive fine particles in contact with the adhesive fine particles was formed as in Examples 1 to 7, the cracking and peeling of the metal film were suppressed, even for metals with high hardness, which improved the conduction reliability after the environmental test. In particular, it was found that excellent adhesion of the metal film can be obtained by forming a metal film with a part where the adhesive fine particles directly contact the surface of the host particle and a part where the conductive fine particles directly contact the surface of the host particle.
10 first composite conductive particle, 11 host particle, 12 adhesive fine particle, 13 conductive fine particle, 14 composite conductive layer, 20 second composite conductive particle, 21 host particle, 22 adhesive fine particle, 23 conductive fine particle, 24 adhesive layer, 25 conductive layer, 101 host particle, 103 metal particle, 104 metal film, 110, 120 metal terminal
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-129750 | Jul 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/026175 | 7/12/2021 | WO |
