Al₂O₃-Cu Substrate with Co-Continuous Phases Made by Powder Sintering Process

Shuangxi Wang; Haifeng Lan; Wenjun Wang; Gaoshan Liu; Dan Zhang

doi:10.3390/ma11081477

Al₂O₃-Cu Substrate with Co-Continuous Phases Made by Powder Sintering Process

Materials (Basel). 2018 Aug 20;11(8):1477. doi: 10.3390/ma11081477.

Authors

Shuangxi Wang¹, Haifeng Lan², Wenjun Wang³, Gaoshan Liu⁴, Dan Zhang⁵

Affiliations

¹ College of Engineering, Shantou University, Shantou 515063, China. sxwang@stu.edu.cn.
² College of Engineering, Shantou University, Shantou 515063, China. 16hflan@stu.edu.cn.
³ College of Engineering, Shantou University, Shantou 515063, China. 14wjwang@alumni.stu.edu.cn.
⁴ College of Engineering, Shantou University, Shantou 515063, China. 12gsliu@alumni.stu.edu.cn.
⁵ College of Engineering, Shantou University, Shantou 515063, China. 13dzhang@alumni.stu.edu.cn.

Abstract

Ceramic-Al substrates with co-continuous ceramic and metal phases, which exhibit high thermal conductivity and compatible coefficient of thermal expansion (CTE), have been widely investigated through the process of die-casting. In this research, a kind of powder sintering process was proposed for fabricating ceramic-Cu composite substrates with co-continuous phases. Copper fiber (Cu_f) has excellent thermal conductivity and large aspect ratio, making it an ideal material to form bridging network structures in the ceramic-Cu composite. To maintain the large aspect ratio of Cu_f, and densify the composite substrate, ZnO-SiO₂-CaO glass was introduced as a sintering additive. Both Al₂O₃/glass/Cu_f and Al₂O₃/30glass/Cu_p composite substrates were hot-pressed at 850 °C under 25 MPa. Experimental results showed that the thermal conductivity of Al₂O₃/30glass/30Cu_f composite substrate was as high as 38.9 W/mK, which was about 6 times that of Al₂O₃/30glass; in contrast, the thermal conductivity of Al₂O₃/30glass/30Cu_p composite substrate was only 25.9 W/mK. Microstructure observation showed that, influenced by hot press and corrosion of molten ZnO-SiO₂-CaO glass, the copper fibers were deformed under hot-pressing, and some local melting-like phenomena occurred on the surface of copper fiber at 850 °C under 25 MPa. The molten phase originating from surface of Cu_f welded the overlapping node of copper fibers during cooling process. Finally, the interconnecting metal bridging in ceramic matrix was formed and behaved as a rapid heat-dissipating channel, which is similar to substrates prepared through die-casting process by porous ceramic and melted Al.

Keywords: Cu fiber; ceramic-based substrate; co-continuous metal phase; powder sintering process; thermal conductivity.