Formation and Growth of Intermetallics at the Interface Between Lead-Free Solders and Copper Substrates

Published

June 16, 2003

Author(s)

Thomas A. Siewert, Juan C. Madeni, S X. Liu

Abstract

Intermetalhc formation and growth were studied for the alloys Sn-3.2Ag-0.8Cu, Sn-3.5Ag, Sn-0.7Cu, and Sn-9Zn.,Coupons of solder joints (prepared by melting some of each solder alloy on a copper-plated circuit board) weresubjected to e@-ag'm-g tests for 20, 100, 200, and 500 hours at 70, 100, and 150 'C. Also, the activation energiesfor the formation of each intermetallic compound and the total intermetallic layer for the four copper-solder systemswere determined. The results confirm that the formation of intermetallic layers is controlled by diffusion and thatthe intermetallic layers grow by thermal activation in a parabolic rnanner. The total thickness of the intermetallicconfounds produced at 150'C for 500 hours and the activation energies for the total inteirmetallic layer in the fourcopper-solder systmm were: 14 @m and 0.74 eV/atom for CuJSn-3.2Ag-O.SCu, 13 tim and 0.85 eV/atom for Cii/Sn-3-5Ag, 14 Jim and 0.68 eV/atom for Cu/Su-0.7Cu, and 19 @m and 0.35 eV/atom for Cu/Sn-9Zn.

Proceedings Title

Proceedings of the APEX Conference on Electronics Manufacturing

Conference Dates

April 1, 2003

Conference Title

Conference on Electronics Manufacturing

Pub Type

Conferences

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Keywords

copper, inetermetallics, lead-free solders, silver, solder, tin

Citation

Siewert, T. , Madeni, J. and Liu, S. (2003), Formation and Growth of Intermetallics at the Interface Between Lead-Free Solders and Copper Substrates, Proceedings of the APEX Conference on Electronics Manufacturing, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851326 (Accessed April 28, 2026)

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