Effect of Ni on the Formation and Growth of Primary Cu6Sn5 Intermetallics in Sn-0.7 wt.%Cu Solder Pastes on Cu Substrates During the Soldering Process

Salleh, Mohd Arif Anuar Mohd; McDonald, Stuart D.; Gourlay, C.M.; Belyakov, S. A.; Yasuda, Hideyuki; Nogita, Kazuhiro

doi:10.1007/s11664-015-4121-x

Cited by 51 publications

(30 citation statements)

References 34 publications

(30 reference statements)

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“…The experimental set-up was similar to previous research [7,10,[21][22][23] and a 21 keV beam was used. The transmission imaging field of view was 877 m x 658 m (1920x1440 pixels) with a resolution of 0.457 m per pixel.…”

Section: Experimental Methodsmentioning

confidence: 99%

Cu6Sn5 crystal growth mechanisms during solidification of electronic interconnections

et al. 2017

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The growth mechanisms of primary Cu6Sn5 are studied in Sn-Cu alloys and solder joints by combining EBSD, FIB-tomography and synchrotron radiography. With increasing cooling rate and Cu content, Cu6Sn5 crystals developed from faceted hexagonal rods to grooved rods, in-plane branched faceted crystals and, finally, to nonfaceted dendrites. This range of growth morphologies has been rationalised into a kinetic microstructure map. Cu6Sn5 hexagonal rods grew along [0001] bounded by {101 ̅ 0} facets and Cu6Sn5 dendrites branched along <405> in the {101 ̅ 0} planes. The faceted to nonfaceted transition indicates a kinetic interface roughening transition and a gradual change in mechanism from lateral growth governed by anisotropic attachment kinetics to continuous growth governed by diffusion and curvature. Finally, it is shown that the full range of Cu6Sn5 morphologies that grew for different composition and cooling rate combinations in bulk alloys can be engineered to grow in solder joints made with a single composition (Sn-0.7wt%Cu/Cu) by altering the peak temperature and the cooling rate.

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Section: Experimental Methodsmentioning

confidence: 99%

Cu6Sn5 crystal growth mechanisms during solidification of electronic interconnections

et al. 2017

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“…It has also been reported by Zeng et al (2014) that Ni additions to Sn0.7Cu solder alloys suppress the Cu3Sn layer intermetallic layer which typically forms between the Cu6Sn5/Cu interface as a result of continuous Cu diffusion from the substrate into the Cu6Sn5 layer. Besides the suppression of the intermetallic layer, Mohd Salleh et al (2016a) revealed that primary Cu6Sn5 in the bulk could be significantly refined with Ni additions. In Sn-Ag-Cu solders, additions of Ni were reported by Chuang and Lin (2003) to also effectively suppress the Cu6Sn5 layer.…”

Section: Introductionmentioning

confidence: 99%

Effects of Ni and TiO2 additions in as-reflowed and annealed Sn0.7Cu solders on Cu substrates

Salleh

McDonald

Nogita

2017

Journal of Materials Processing Technology

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“…The real time observation experiments were performed at BL20XU beamline in the SPring-8 synchrotron using an in-situ synchrotron X-ray real time solidification observation setup developed in previous research [39][40][41][42]. The parameters were chosen to allow a high degree of coherence, absorption contrast and phase contrast enabling boundaries in the sample to be …”

Section: Synchrotron X-ray Radiography Imagingmentioning

confidence: 99%

Suppression of Cu 6 Sn 5 in TiO 2 reinforced solder joints after multiple reflow cycles

et al. 2016

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In the current generation of 3D electronic packaging, multiple reflows are often required during soldering. In addition, electronic packages may be subjected to additional solder rework or other heating processes. This paper investigates the effects of multiple reflow cycles on TiO2 reinforced Sn-0.7Cu solder fabricated by a powder metallurgy microwave sintering technique.Compared to TiO2-free equivalents, a relative suppression of the Cu6Sn5 phase, both as primary crystals and as an interfacial layer was observed. The likely mechanism relates to the TiO2 nanoparticles promoting nucleation and decreasing the amount of time that liquid is in contact with the interfacial layer. The TiO2 particles appear to stabilise the interfacial Cu6Sn5 layer and result in a more planar morphology. The suppression of Cu6Sn5 results in TiO2 reinforced solder joints having a higher shear strength after multiple reflow cycles compared to Sn-0.7Cu solder joints. IntroductionSolder alloys play a crucial role in determining performance and reliability in the assembly and interconnection of electronic products and have electrical, thermal and mechanical functions [1,2]. The relative importance of solder alloy properties has increased due to continued miniaturization of microelectronic circuitry and the use of finer pitch interconnects. Higher functional densities in printed circuit boards (PCB) have been made possible by surface mount technology (SMT) using reflow soldering, often with multiple reflow cycles. Other heating cycles can be present in manufacturing such as additional solder rework [3]. One challenge associated with current generation Pb-free solder alloys is that during multiple thermal cycles, the joint strength may degrade due to the rapid growth of the interfacial layer of intermetallic compounds [4][5][6][7][8][9][10][11][12]. In a typical Pb-free solder joint, Cu6Sn5, which may form either as primary crystals or an interfacial layer during soldering can play a determining role in solder joint strength. There is evidence that by suppressing the Cu6Sn5 interfacial layer, solder joint properties could be improved [13][14][15][16][17] and as such there are benefits associated with controlling the growth of this layer during multiple reflows.It has recently been reported that additions of reinforcement to a variety of solder matrices, with compounds including silicon carbide (SiC) [18][19][20], nickel oxide (NiO) [21], alumina (Al2O3) [22][23][24], zirconia (ZrO2) [25][26][27][28], titanium oxide (TiO2) [29][30][31][32][33][34] and silicon nitride (Si3N4) [35,36] result in suppression of the growth of the interfacial layer during soldering [37]. In our recent study [38], we developed a method of fabricating a reinforced solder using a powder metallurgy microwave sintering method that results in a homogeneous distribution of TiO2 in the solder material and an improvement in the bulk solder material thermal and mechanical properties. However, properties related to the solder joint strength after multiple reflows of t...

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Effect of Ni on the Formation and Growth of Primary Cu6Sn5 Intermetallics in Sn-0.7 wt.%Cu Solder Pastes on Cu Substrates During the Soldering Process

Cited by 51 publications

References 34 publications

Cu6Sn5 crystal growth mechanisms during solidification of electronic interconnections

Cu6Sn5 crystal growth mechanisms during solidification of electronic interconnections

Effects of Ni and TiO2 additions in as-reflowed and annealed Sn0.7Cu solders on Cu substrates

Suppression of Cu 6 Sn 5 in TiO 2 reinforced solder joints after multiple reflow cycles

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