Effect of particle size distribution on the mechanical and electrical properties of reverse-offset printed Sn–Ag–Cu solder bumps

A reduction of the particle size used in solder pastes was shown to affect the electrical and mechanical properties of finely printed solder bumps. Sn–3.0Ag–0.5Cu solder nanoparticles were synthesized using a radio frequency thermal plasma system, and solder pastes were formulated for reverse-offset...

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Bibliographic Details
Published in:Journal of materials science. Materials in electronics 2018-12, Vol.29 (23), p.19620-19631
Main Authors: Son, Min-Jung, Jeong, Jae Won, Kim, Hyunchang, Lee, Taik-Min, Lee, Hoo-Jeong, Kim, Inyoung
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemical precipitation
Chemistry and Materials Science
Copper
Electrical properties
Intermetallic compounds
Materials Science
Mechanical properties
Nanoparticles
Offset printing
Optical and Electronic Materials
Particle size
Particle size distribution
Pastes
Resistance
Shear strength
Silver
Solidification
Supercooling
Thermal plasmas
Tin
Tin base alloys
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Summary:A reduction of the particle size used in solder pastes was shown to affect the electrical and mechanical properties of finely printed solder bumps. Sn–3.0Ag–0.5Cu solder nanoparticles were synthesized using a radio frequency thermal plasma system, and solder pastes were formulated for reverse-offset printing of solder bump arrays with a size of 30 µm. As the nanoparticle ratio in the paste increased, the degree of supercooling, ΔT, increased with a separation of the exothermic peaks for the solidification of β-Sn and the precipitation of intermetallic compounds (IMCs). The networks of finely precipitated IMCs formed at the boundaries of large β-Sn increased the shear strength to 73 MPa. However, insufficient flux deteriorated the electrical and mechanical properties because it delayed the solidification of primary β-Sn as well as the melting of the solder. As a result, the Sn–3.0Ag–0.5Cu solder paste containing a nanoparticle ratio of 25% exhibited an optimum printability for reverse-offset printing of solder bumps, and the resulting bumps had an electrical conductance of 0.4 mΩ and a shear strength of 73 MPa.
ISSN:0957-4522
1573-482X
DOI:10.1007/s10854-018-0021-1