Effects of current density and temperature on Sn/Ni interfacial reactions under current stressing

Wang, Chao-hong; Kuo, Chao‐Yin; Chen, Hsien-hsin; Chen, Sinn-wen

doi:10.1016/j.intermet.2010.09.010

Cited by 51 publications

(9 citation statements)

References 18 publications

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“…The rapid diffusion of Cu away from the cathode leads to the excess dissolution of intermetallic compounds and the cathode material [3,4]. Excessive dissolution of the cathode frequently leads to a distinctive serrated interface, with most of the serrated teeth inclined toward a specific direction [5][6][7][8][9][10][11]. The sequence of events in the early stage has previously been described in detail, and the initiation of the formation of the serrated interface has been shown to be related to preferential dissolution at the Cu 6 Sn 5 grain boundaries [5].…”

Section: Introductionmentioning

confidence: 99%

Dominant effects of Sn orientation on serrated cathode dissolution and resulting failure in actual solder joints under electromigration

Yang

et al. 2015

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 99%

Dominant effects of Sn orientation on serrated cathode dissolution and resulting failure in actual solder joints under electromigration

Yang

et al. 2015

Journal of Alloys and Compounds

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“…At the same time, it is known that non-equilibrium Sn-Ni intermetallics can form in Sn-Ni couples after soldering or during storage at elevated temperatures. In most cases non-equilibrium Sn-Ni compounds such as Ni3Sn8 [16], NiSn3 [17][18][19][20][21] and NiSn4 [22][23][24] were found after solid state ageing or thermal cycling [16][17][18][19][21][22][23][24] or after heat treatments combined with electric current passage through the joint [19,22]. Figure 2A is an example of non-equilibrium NiSn4 formed at the interface during solid state ageing of Sn-Ni electroplated couples.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Cu on Metastable NiSn4 in Sn-3.5Ag-xCu/ENIG Joints

Belyakov

Gourlay

2015

Journal of Elec Materi

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We explore the effect of dilute Cu additions on the suppression of metastable βSn-NiSn4 eutectic growth in solder joints between Sn-3.5Ag-xCu solders and Ni-based substrates.In Sn-3.5Ag/electroless nickel immersion gold (ENIG) or Sn-3.5Ag/Ni solder joints, it is shown that the eutectic mixture contains Sn, Ag3Sn and metastable NiSn4. It is found that additions of only 0.005wt%Cu to Sn-3.5Ag-xCu/ENIG or Sn-3.5Ag-xCu/Ni joints promote the formation of stable βSn-Ni3Sn4 eutectic and that both Ni3Sn4 and NiSn4 exist in the eutectic at this Cu level. It is further shown that for the full prevention of metastable NiSn4 during eutectic solidification of the solder joint, more considerable Cu additions of at least 0.3wt%Cu are required.Keywords: Microstructure, Pb-free soldering, Metastable, NiSn4, Intermetallics, Solidification INTRODUCTIONSn-Ag solders are a popular choice for consumer and power electronics [1] and the composition is frequently used on Ni-containing surface finishes, such as electroless nickel immersion gold (ENIG) and electroless nickel, electroless palladium immersion gold (ENEPIG), and on Ni-based UBMs (underbump metallizations). Solder reactions in the Sn/Ni and Sn-Ag/Ni systems and subsequent microstructure evolution have been widely studied [2][3][4][5][6][7][8][9][10][11][12][13][14][15] and most researchers reported Ni3Sn4 as the major interfacial reaction product in such systems, similar to that shown in Figure 1A. At the same time, it is known that non-equilibrium Sn-Ni intermetallics can form in Sn-Ni couples after soldering or during storage at elevated temperatures. In most cases non-equilibrium Sn-Ni compounds such as Ni3Sn8 [16], and NiSn4 [22][23][24] were found after solid state ageing or thermal cycling [16][17][18][19][21][22][23][24] or after heat treatments combined with electric current passage through the joint [19,22]. Figure 2A is an example of non-equilibrium NiSn4 formed at the interface during solid Figure 2B). In contrast, when soldered to Alloy42, the FeSn2 interfacial intermetallic layer serves as an efficient diffusion barrier limiting the amount of Ni that dissolves into the liquid solder during reflow [28,29].As result, this type of solder joints has less NiSn4 in the bulk solder than on Ni or ENIG substrates( Figure 2D). We have also found that trace Fe additions promote metastable NiSn4 formation due to epitaxial nucleation of NiSn4 on FeSn2 particles [30].We have recently demonstrated [27] that industrially important Sn-3.5Ag/ENIG or Sn-3.5Ag/Ni joints also solidify to contain metastable Sn-NiSn4 eutectic ( Figure 2A-C, E). Surprisingly, despite the fact that Sn-Ag solders have been used on Ni-containing substrates for decades, this phenomenon was missed in past research. NiSn4 is a metastable phase and can transform into equilibrium Ni3Sn4 and βSn whilst the solder joint is in service at elevated temperatures [25,27]. In automotive and power electronics, operation temperatures are relatively high (175-200°C) and microstructural stability and reliabil...

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“…However, NieSn soldered joints and diffusion couples are occasionally reported to contain additional non-equilibrium intermetallics in the reaction zone. For example, 'Ni 3 Sn 7 ' [2], 'Ni 3 Sn 8 ' [3], 'NiSn 3 ' [4e8], 'NiSn 4 ' [9e11] and 'NiSn 9 ' [12] have been reported in (i) solid state heat treated or thermallycycled Sn/Ni plated layers [3,5,10,11,13], (ii) Sn/Ni reaction couples [4,6,8,9], (iii) solder joints in the as-soldered state [7] and (iv) deposited SneNi alloy coatings [12]. Fig.…”

Section: Introductionmentioning

confidence: 99%

“…soldered joints, plated layers or diffusion couples) and often after thermal cycling at temperatures of e 40. þ 195 C [3e6,8e11,13]. The fastest growth rate of 'NiSn 3 /NiSn 4 ' in reaction couples is reported to be in the range 100e170 C [3e5, 8], and passing an electric current through a solder joint between Ni and Sn has been shown to promote 'NiSn 3 /NiSn 4 ' growth at 100 C, but not at temperatures above 180 C [6,9]. Furthermore, the nucleation and growth of the non-equilibrium phases has been found to depend on the nature of the Ni substrate (bright, matte etc.…”

Section: Introductionmentioning

confidence: 99%