Composite microparticles

Abstract

This invention relates to a composite microparticle, wherein at least a portion of the surface of copper microparticles is coated with a dispersant. The average particle size D50 of the composite microparticles is 50 nm to 350 nm. In a particle size histogram based on the number of composite microparticles, the particle size D10 at a cumulative frequency of 10% and the particle size D90 at a cumulative frequency of 90% satisfy the relationship D90 / D10 ≤ 4.0. The dispersant is an ethylene polymer having a carboxyl group and comprising the structure represented by the following formula (1). In the following formula (1), R1 is a hydrogen atom or a methyl group, and R2 is an organic group comprising a cyclic structure or an organic group comprising a linear chain structure having 3 or more carbon atoms.