| 摘要 |
PROBLEM TO BE SOLVED: To enlarge the current capacity at the time of connection with low connection resistance, and to prevent the generation of leak phenomenon while stabilizing the connection by using metal balls having a mean grain sige at a specified value, an aspect ratio less than a specified value and a CV value at a specified value or less. SOLUTION: Metal balls having a mean grain size at 0.3-25μm is used, and an aspect ratio of this metal ball is set at a value less than 1.5, and a CV value thereof is set at 40% or less. In this case, the metal ball having such a mean grain diameter, aspect ratio and CV value can be obtained by observing 300, for example, desirable metal balls with an electronic microscope, or obtained by dispersing the metal balls in the dispersion medium and classifying on the basis of the falling speed. In this case, in order to prevent the generation of a phenomenon that the metal grains are adhered to each other so as to perform the accurate classifying operation, concentration of the metal balls in the dispersion medium is lowered. Furthermore, the metal ball is provided with projections, and while coated with a resin so as to stabilize the conductive connecting property, and generation of short-circuit between electrodes can be prevented.
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