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In this study, we explore the structure-property relationship of sintered metal nano/microparticles from the perspective of the agglomerate size effect. Through sintering experiments and mechanical tests of Cu particle pastes with different solvents, a linear correlation between the agglomerate size in the particle paste (L a) and the size of large-scale cavities in the sintered structure (L c) is revealed, and a negative correlation between the cavity size and the shear strength of the sintered structure is discovered. Based on these results, a quantitative model is proposed to predict the overall strength of the sintered structure (τ f). A relationship τ f = τ c /(1 + √(2 L cmax / d)) is established, which fits the experimental results very well. The model reveals that the relative agglomerate size (L a / d) or relative cavity size (L c / d) plays a more important role than the particle size (d) itself in terms of defining the final sintering properties of metal nano/microparticles. [Display omitted] • The structure-property relation of sintered metal particles is explored • A linear correlation between agglomerate size and sintered cavity size is revealed • The cavity size and shear strength follow a relation of τ c / 1 + 2 L cmax / d • The relative cavity size (L c / d) is the key to determining the strength [ABSTRACT FROM AUTHOR]

A green method for the synthesis of in situ Cu paste is developed. Cu particles are prepared through chemical reduction by selecting a special copper source, reducing agent, and solvent. Then the reaction solution is directly concentrated to obtain an in situ Cu paste. The synthesis of Cu particles and the preparation of Cu paste are conducted simultaneously, and the process of separation, purification, drying, storage, and re-dispersion of powder are reduced. Particles are not directly exposed to air, thus the oxidation of micro/submicron -Cu is effectively prevented, and the agglomeration of particles caused by drying and dispersion operations is simultaneously reduced. Furthermore, the proposed method has a certain universality, and different types of Cu sources can be used to prepare in situ paste with different sizes and morphologies. The entire preparation process is simple, efficient, green, and the yield can reach 99.99%, which breaks through the bottleneck of the application of traditional micro/submicron-Cu materials. Copper acetate-based in situ paste is sintered for 30 min at 260 °C and 2 MPa in a reducing atmosphere. The shear strength, resistivity, and thermal conductivity reach 55.26 MPa, 4.01 × 10â€"8 Ω·m, and 92.75 W/(m·K), respectively, which could meet the interconnection application of power semiconductor devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-purity, spherical Ag NPs with a size of ∼5 nm are synthesized by spark ablation. • A solvent-assisted sintering method is developed to improve the sintering properties. • The shear strength of the sintered Ag NPs at 180 °C is improved from 0 to 37.1 MPa. • A compact and void-free sintered structure is obtained by the sintering method. • Correlations between solvent wettability, agglomerate size and void size are revealed. Through the spark ablation method, high purity, spherical silver nanoparticles (Ag NPs) with a size of 5 ± 3 nm are prepared. A solvent-assisted sintering method is developed to modulate the sintering structure and properties of the as-prepared Ag NPs. The effects of the solvents terpineol, polyethylene glycol-200, 1,2-propanediol, and ethylene glycol are explored. The results show that treatment with ethylene glycol causes the shear strength of the sintered Ag NPs at 180, 220, 260, and 300 °C to significantly improve from 0, 3.7, 22.1, and 64.6 MPa to 37.1, 56.1, 76.6, and 93.1 MPa respectively. Additionally, the size and number of voids in the sintered structure are significantly reduced. From the perspective of the capillary pressure induced by the solvent during sintering, a correlation between low solvent wettability and small agglomerate size of the Ag NPs is revealed, which reasonably explains the structure and properties of the sintered Ag NPs that were treated with different solvents. The spark ablation and solvent-assisted sintering methods provide a new approach for the fabrication and structure–property design of metal NPs for electronic applications. [ABSTRACT FROM AUTHOR]