Agglomeration of Ag3Sn compounds in microbumps during reflow for 3D-IC packaging

Ruo Wei Yang, Yuan Wei Chang, Chih Chen*, Tao Chih Chang, Chau Jie Zhan, Jin Ye Juang

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In this study, we study the metallurgical reactions at liquid state for different thickness Sn2.5Ag solder microbumps with Cu/Ni UBM. After 260 °C reflow, we observed that the intermetallic compounds (IMCs) at chip side and interposer side both were Ni3Sn4 IMCs. As reflow time increased, the thickness of Ni3Sn4 IMCs and the concentration of Ag in the solder increased. We calculated the Ni 3Sn4 IMCs growth rate constant was 0.45 μm/min 1/2. In addition, the dispersed Ag3Sn compound agglomerate to form plate-like Ag3Sn compound as reflow time increased. We used the Ni3Sn4 IMCs growth rate constant to define the critical volume of Sn2.5Ag solder was 1088 μm3. If the volume of the Sn2.5Ag microbumps was below the critical volume, the concentration of Ag in the remaining solder would over 3.5 wt.%, and the plate-like Ag3Sn would appear in the remaining solder after 10 min of reflowing at 260 °C.

Original languageEnglish
Title of host publicationInternational Microsystems Packaging Assembly and Circuits Technology Conference, IMPACT 2010 and International 3D IC Conference, Proceedings
DOIs
StatePublished - 1 Dec 2010
Event2010 5th International Microsystems, Packaging, Assembly and Circuits Technology Conference, IMPACT 2010 and International 3D IC Conference - Taipei, Taiwan
Duration: 20 Oct 201022 Oct 2010

Publication series

NameInternational Microsystems Packaging Assembly and Circuits Technology Conference, IMPACT 2010 and International 3D IC Conference, Proceedings

Conference

Conference2010 5th International Microsystems, Packaging, Assembly and Circuits Technology Conference, IMPACT 2010 and International 3D IC Conference
CountryTaiwan
CityTaipei
Period20/10/1022/10/10

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