Joining of Pure Copper Using Cu Nanoparticles Derived from CuO Paste

• Fujimoto Tomoyuki

  Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University

• Ogura Tomo

  Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University

• Sano Tomokazu

  Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University

• Takahashi Makoto

  Joining and Welding Research Institute, Osaka University

• Hirose Akio

  Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University

Abstract

A paste containing CuO particles and polyethylene glycol 1000 as a reducing solvent has been applied to joining pure Cu in electronic applications, and the bondability of the joints and bonding mechanism were investigated. Based on a combination of thermogravimetric and differential thermal analysis, pressurization in the bonding process was determined to be started at temperatures near the exothermal peak of 320°C. Pressurization started at a temperature of 320°C, with the 11 MPa shear strength of the Cu-to-Cu joint being 2.4 times greater than a joint pressed at room temperature. During the bonding process, CuO particles were not directly reduced to Cu, but were instead first reduced to Cu₂O nanoparticles, which were subsequently reduced to Cu nanoparticles, and an oxide film of a Cu substrate was also reduced, thus ensuring a direct connection between a sintered Cu layer and substrate. The shear strength increases with holding time. Moreover, the shear strength of a joint created with CuO paste and a holding time of 15 min (20 MPa) is in fact higher than what can be achieved using a conventional lead-rich Pb-5Sn solder, thus making it well-suited for use in electronic applications.

Journal

• MATERIALS TRANSACTIONS

  MATERIALS TRANSACTIONS 56 (7), 992-996, 2015

  The Japan Institute of Metals and Materials

Keywords

• copper nanoparticles
• copper oxide
• reduction
• copper joint

Details

• CRID: 1390282679230246784
• NII Article ID: 130005083559
• NII Book ID: AA1151294X
• DOI: 10.2320/matertrans.mi201410
• ISSN: 13475320
• ISSN: 13459678
• NDL BIB ID: 026564570
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I026564570
• Web Site: https://www.jstage.jst.go.jp/article/matertrans/56/7/56_MI201410/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed