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Improvement of Electrochemical Migration Resistance by Cu/Sn Intermetallic Compound Barrier on Cu in Printed Circuit Board

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A thin Sn coating was coated on the Cu electrodes on a printed circuit board (PCB) and annealed to form Cu/Sn intermetallic compounds (IMCs). Electrochemical migration (ECM) characteristics were investigated with respect to coating thickness, conductor spacing, and potential bias. From the anodic polarization test, the corrosion current of Cu/Sn IMCs was reduced to nearly two orders of magnitude at 0.217 V (versus saturated calomel electrode) compared to pristine Cu. The corrosion resistance of Cu/Sn IMCs was improved. Water drop test (WDT) results revealed that mean time to failure also increased over 50 times on the sample with the Sn coating (160 nm) at 50-μm spacing compared to the pristine Cu and a thick Sn coating (160 nm) was more effective than thin Sn coating (90 nm) due to the formation rate of IMCs. Passivity behavior and pitting corrosion were observed in both the anodic polarization test and the WDT. The graph of current-density potential in the anodic polarization test and the TTF potential in the WDT showed a quite similar curve shape. Therefore, dissolution step is the ratedetermining step in ECM and governs the entire ECM process. Cu/Sn IMCs can be a new alternative surface barrier to improve the ECM resistance of Cu electrodes on PCBs.

Index Terms—Electrochemical process (ECM), failure analysis, printed circuits (PCs), reliability testing.

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Ketersediaan

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Informasi Detail

Judul Seri

IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY

No. Panggil

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Penerbit

New York : IEEE., 2014

Deskripsi Fisik

IEEE TRANSACTIONS ON DEVICE AND MATERIALS RELIABILITY, VOL. 14, NO. 1, MARCH 2014

Bahasa

English

ISBN/ISSN

DOI: 10.1109/TDMR.20

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

VOL. 14, NO. 1, MARCH 2014

Subjek

ELEKTRONIK

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

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