Rapid sintering by thermo-compression in air using a paste containing bimodal-sized silver-coated copper particles and effects of particle size and surface finish type

• Published in: Journal of alloys and compounds 2022-03, Vol.897, p.163223, Article 163223
• Main Authors: Choi, Eun Byeol, Lee, Yun-Ju, Lee, Jong-Hyun
• Format: Article
• Language: English
• Subjects: Copper; High temperature; Mechanical properties; Metal matrix composites; Powder metallurgy; Rapid prototyping; Shear strength; Silver; Sinterability; Sintering; Substrates; Surface finish; Surfaces and interfaces; Thermal analysis
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.163223

•Bimodal-sized Cu@Ag particles and novel reductant were adopted for fast sintering.•Sintering in between Ag finishes was performed using pastes containing the bimodal Cu@Ag.•200-nm particles, as the second size, exhibited the most remarkable sintering properties.•Only 3-min sintering at 300 °C in air under compression exhibited a strength of 20.7 MPa.•The remarkable sintering properties in air were maintained even in between Cu finishes. [Display omitted] To rapidly form a highly thermal-conductive line structure that could be sustained even at high temperatures such as 300 °C, the compression (5 MPa)-assisted sintering of a Ag-finished die on an Ag-finished substrate was performed in air employing a paste containing bimodal-sized Ag-coated Cu (Cu@Ag) particles at a ratio of 6 (1.5 µm):4 (800, 400, and 200 nm). The 200-nm particles among the submicrometer-sized particles provided the most enhanced sinterability on both joint strength and microstructure. Accordingly, the 1.5-µm/200-nm Cu@Ag paste exhibited excellent shear strength surpassing 20 MPa, accompanied with a near full-density structure, even by the short sintering for 3 min. The strength eventually exceeded 45 MPa after 10 min. These results demonstrate the successful development of an effective paste to achieve rapid sintering even in air with low material cost.