Comparative Thermal and Structural Characterization of Sintered Nano-Silver and High-Lead Solder Die Attachments During Power Cycling

Dai, Jingru; Li, Jianfeng; Agyakwa, Pearl; Corfield, Martin; Johnson, Christopher Mark

Abstract

13.5 mm × 13.5 mm sintered nano-silver attachments for power devices onto AlN substrates were prepared at 250 ºC and a pressure of 10MPa for 5 minutes and compared with Pb5Sn solder joint die attachments under constant current power cycling with an initial temperature swing of 50-175 ºC. Both the effective thermal resistance and microstructural evolution of the samples were monitored using transient thermal impedance measurement and non-destructive X-ray computed tomography at regular power cycling intervals. The results showed a gradual increase in the effective thermal resistance of the Pb5Sn solder joints from 0.047 to 0.133 K/W from zero to 41k power cycles, followed by a rapid escalation to 0.5018 K/W at 52k cycles. This was accompanied with the formation and development of oblique cracks within the Pb5Sn die attachments until delamination occurred at the solder/device and solder/substrate interfaces. By contrast, the effective thermal resistance of the sintered Ag joints remained almost constant at 0.040 K/W up to 116k power cycles. This was explained in terms of thermally induced continuation of densification of the sintered structure and the formation and development of networked vertical cracks within the sintered Ag die attachments, some of which further extended into the Cu tracks of the AlN substrate.

Citation

Dai, J., Li, J., Agyakwa, P., Corfield, M., & Johnson, C. M. (2018). Comparative Thermal and Structural Characterization of Sintered Nano-Silver and High-Lead Solder Die Attachments During Power Cycling. IEEE Transactions on Device and Materials Reliability, 18(2), 256-265. https://doi.org/10.1109/TDMR.2018.2825386

• Journal Article Type: Article
• Acceptance Date: Apr 3, 2018
• Online Publication Date: Apr 12, 2018
• Publication Date: 2018-06
• Deposit Date: Apr 11, 2018
• Publicly Available Date: Apr 12, 2018
• Journal: IEEE Transactions on Device and Materials Reliability
• Print ISSN: 1530-4388
• Electronic ISSN: 1558-2574
• Publisher: Institute of Electrical and Electronics Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 18
• Issue: 2
• Pages: 256-265
• DOI: https://doi.org/10.1109/TDMR.2018.2825386
• Keywords: Sintered nanosilver joint, high lead solder joint, power cycling, thermal impedance and microstructures
• Public URL: https://nottingham-repository.worktribe.com/output/923275
• Publisher URL: https://ieeexplore.ieee.org/document/8337010/
• Contract Date: Aug 21, 2018