Embodiments of the present invention relate to methods for preparing high optical density solutions of nanoparticle, such as nanoplates, silver nanoplates or silver platelet nanoparticles, and to the solutions and substrates prepared by the methods. The process can include the addition of stabilizing agents (e.g., chemical or biological agents bound or otherwise linked to the nanoparticle surface) that stabilize the nanoparticle before, during, and/or after concentration, thereby allowing for the production of a stable, high optical density solution of silver nanoplates. The process can also include increasing the concentration of silver nanoplates within the solution, and thus increasing the solution optical density.

One object of the present invention is to provide a bonding material capable of forming a highly reliable bond, the present invention provides a bonding material having a plate shape or a sheet shape, wherein the bonding material includes: fine copper particles having an average particle diameter of 300 nm or less; coarse copper particles having an average particle diameter of 3 .Math.m or more and 11 .Math.m or less; and a reducing agent which reduces the fine copper particles and the coarse copper particles.

In the joined body (10) in which the conductor (12) and the substrate (14) are joined by the joining material (13), the joining material (13) includes a sintered body formed by sintering silver powder. A sintered body having a porosity of 8% to 30% and a surface roughness Ra of a joining surface of 500 nm or more and 3.3 μm or less is adopted.

Provided is a method for producing a joined body, the method including a first step of preparing a laminated body which includes a first member having a metal pillar provided on a surface thereof, a second member having an electrode pad provided on a surface thereof, and a joining material provided between the metal pillar and the electrode pad and containing metal particles and an organic compound, and a second step of heating the laminated body to sinter the joining material at a predetermined sintering temperature, in which the joining material satisfies the condition of the following Formula (I):
(M.sub.1−M.sub.2)/M.sub.1×100≥1.0  (I)
[in Formula (I), M.sub.1 represents a mass of the joining material when a temperature of the joining material reaches the sintering temperature in the second step, and M.sub.2 represents a non-volatile content in the joining material.]

There is a problem that when a silver powder sintering paste that is substantially free from resin is used, an organic solvent used as a dispersion medium bleeds, which results in contamination and wire bonding defects. In order to solve the problem, provided is a metal powder sintering paste that contains, as a principal component, silver particles having an average particle diameter (a median diameter) of 0.3 μm to 5 μm and further contains an anionic surfactant but is substantially free from resin.

There is a problem that when a silver powder sintering paste that is substantially free from resin is used, an organic solvent used as a dispersion medium bleeds, which results in contamination and wire bonding defects. In order to solve the problem, provided is a metal powder sintering paste that contains, as a principal component, silver particles having an average particle diameter (a median diameter) of 0.3 μm to 5 μm and further contains an anionic surfactant but is substantially free from resin.

Provided is a plurality of flaky magnetic metal particles of embodiments, each flaky magnetic metal particle having a flat surface having either or both of a plurality of concavities and a plurality of convexities, the concavities or convexities being arranged in a first direction and each having a width of 0.1 μm or more, a length of 1 μm or more, and an aspect ratio of 2 or higher; and a magnetic metal phase containing at least one primary element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The flaky magnetic metal particles have an average thickness of between 10 nm and 100 μm inclusive, and the average value of the ratio of the average length within the flat surface with respect to the thickness is between 5 and 10,000 inclusive.

Provided is a plurality of flaky magnetic metal particles of embodiments, each flaky magnetic metal particle having a flat surface having either or both of a plurality of concavities and a plurality of convexities, the concavities or convexities being arranged in a first direction and each having a width of 0.1 μm or more, a length of 1 μm or more, and an aspect ratio of 2 or higher; and a magnetic metal phase containing at least one primary element selected from the group consisting of iron (Fe), cobalt (Co), and nickel (Ni). The flaky magnetic metal particles have an average thickness of between 10 nm and 100 μm inclusive, and the average value of the ratio of the average length within the flat surface with respect to the thickness is between 5 and 10,000 inclusive.

A method is disclosed for producing flakes of a first material, the method comprising: a) supporting two supply cylinders of the first material and a fatiguing rod assembly, that includes at least one textured fatiguing rod, so that each fatiguing rod is sandwiched between the two cylinders, each fatiguing rod having a diameter smaller than an initial diameter of the two supply cylinders and being made of a second harder material; b) urging the surfaces of the two supply cylinders into contact with each fatiguing rod; and c) causing the supply cylinders and the fatiguing rod(s) to rotate while making rolling line contact with one another; wherein the supply cylinders and each fatiguing rod are urged against one another with sufficiently high contact pressure to modify the surface of the supply cylinders by fatigue and result in separation of flakes from the surfaces of the cylinders.

A method is disclosed for producing flakes of a first material, the method comprising: a) supporting two supply cylinders of the first material and a fatiguing rod assembly, that includes at least one textured fatiguing rod, so that each fatiguing rod is sandwiched between the two cylinders, each fatiguing rod having a diameter smaller than an initial diameter of the two supply cylinders and being made of a second harder material; b) urging the surfaces of the two supply cylinders into contact with each fatiguing rod; and c) causing the supply cylinders and the fatiguing rod(s) to rotate while making rolling line contact with one another; wherein the supply cylinders and each fatiguing rod are urged against one another with sufficiently high contact pressure to modify the surface of the supply cylinders by fatigue and result in separation of flakes from the surfaces of the cylinders.