Wetting Behaviors of Sn-Based Solders on Cu and Pd Surfaces

1995 ◽  
Vol 390 ◽  
Author(s):  
H. K. Kim ◽  
Y. Wang ◽  
A. Maheshwari ◽  
K. N. Tu
Keyword(s):  
Surface Morphology ◽  
Classical Model ◽  
Layered Compound ◽  
Quasi Equilibrium ◽  
Compound Formation ◽  
Snpb Solder ◽  
Wetting Behaviors ◽  
Pure Sn ◽  
Compound Surface ◽  
Eutectic Snpb

ABSTRACTWe have studied the surface morphology and wetting reaction of eutectic SnBi, eutectic SnPb, and pure Sn on Cu and Pd surfaces. In the case of Pd, the reactions were so fast that no quasi-equilibrium wetting angle could be measured. The compound formation has changed not only the interfaces but also the surfaces. Due to the formation of a reaction band outside the solder cap, the SnPb solder is no longer wetting the Cu surface but rather the Cu-Sn compound surface. In the wetting interface between eutectic SnPb and Cu, the morphology of the scallop-like Cu-Sn compound grains shows that we may not apply the classical model of layered compound growth to analyze the rate of soldering reactions.

scholarly journals Cross interactions on interfacial compound formation of solder bumps and metallization layers during reflow

2004 ◽  
Vol 19 (12) ◽  
pp. 3654-3664 ◽  
Author(s):  
T.L. Shao ◽  
T.S. Chen ◽  
Y.M. Huang ◽  
Chih Chen
Keyword(s):  
Flip Chip ◽  
Driving Forces ◽  
The Other ◽  
Compound Formation ◽  
Bump Height ◽  
Performance Requirements ◽  
Substrate Side ◽  
Solder Bumps ◽  
Snpb Solder ◽  
Eutectic Snpb

While the dimension of solder bumps keeps shrinking to meet higher performance requirements, the formation of interfacial compounds may be affected more profoundly by the other side of metallization layer due to a smaller bump height. In this study, cross interactions on the formation of intermetallic compounds (IMCs) were investigated in eutectic SnPb, SnAg3.5, SnAg3.8Cu0.7, and SnSb5 solders jointed to Cu/Cr–Cu/Ti on the chip side and Au/Ni metallization on the substrate side. It is found that the Cu atoms on the chip side diffused to the substrate side to form (Cux,Ni1−x)6Sn5 or (Niy,Cu1−y)3Sn4 for the four solders during the reflow for joining flip chip packages. For the SnPb solder, Au atoms were observed on the chip side after the reflow, yet few Ni atoms were detected on the chip side. In addition, for SnAg3.5 and SnSn5 solders, the Ni atoms on the substrate side migrated to the chip side during the reflow to change binary Cu6Sn5 into ternary (Cux,Ni1−x)6Sn5 IMCs, in which the Ni weighed approximately 21%. Furthermore, it is intriguing that no Ni atoms were detected on the chip side of the SnAg3.8Cu0.7 joint. The possible driving forces responsible for the diffusion of Au, Ni, and Cu atoms are discussed in this paper.

Morphology of instability of the wetting tips of eutectic SnBi, eutectic SnPb, and pure Sn on Cu

1995 ◽  
Vol 10 (3) ◽  
pp. 497-504 ◽  
Author(s):  
H.K. Kim ◽  
H.K. Liou ◽  
K.N. Tu
Keyword(s):  
Solder Joint ◽  
Surface Morphology ◽  
Intermetallic Compounds ◽  
Rough Surface ◽  
Environmental Issue ◽  
Wetting Angle ◽  
Angle Change ◽  
Microelectronics Industry ◽  
Pure Sn ◽  
Eutectic Snpb

The Pb-based solder used in microelectronics industry is becoming an environmental issue. To understand the wetting behavior of solders with and without Pb, we have studied the surface morphology and wetting reaction of eutectic SnBi, eutectic SnPb, and pure Sn on Cu through the measurements of wetting angle change and wetting tip stability by SEM and EDX. The wetting angle remains constant after the initial spread, but the eutectic SnPb/Cu continues to react and forms a reaction band in front of the solder edge as well as intermetallic compounds at the interface. For eutectic SnBi/Cu, there is no reaction at the wetting tip, and the wetting angle does not change much; however, the interfacial reaction between eutectic SnBi and Cu forms intermetallic compounds at the solder joint; the wetting tip is not in a static equilibrium. A rough surface and edge was observed on the eutectic SnBi/Cu joint, but the eutectic SnPb/Cu has a smoother surface and edge.

Fast Soldering Reactions on Au Foils

1996 ◽  
Vol 445 ◽  
Author(s):  
P.G. Kim ◽  
K.N. TU
Keyword(s):  
Intermetallic Compounds ◽  
Wetting Angle ◽  
High Solubility ◽  
Reflow Time ◽  
X Ray ◽  
Intermetallic Compound Growth ◽  
Wetting Behaviors ◽  
Pure Sn ◽  
Eutectic Snpb

AbstractWe have studied the wetting behaviors and interfacial reactions of Pb‐containing (63Sn‐37Pb, 95Pb‐5Sn) and Pb‐free solders (pure Sn, 96Sn‐4Ag, 57Bi‐43Sn, 77.2Sn‐20In‐2.8Ag) on Au foils in order to understand the role of Pb in Pb‐based solders. Surface morphology, wetting angle, and interfacial reaction of the solders were studied by Scanning Electron Microscopy (SEM) and Energy Dispersive X‐ray Analysis (EDX). Pb‐containing and Pb‐free solders (pure Sn, 96Sn‐4Ag, 77.2Sn‐20In‐2.8Ag) showed rough surfaces due to the precipitation of intermetallic compounds on the surface of the solder caps. The eutectic SnBi (57Bi‐43Sn) solder, however, showed a smoother surface. The wetting angle of the eutectic SnPb (63Sn‐37Pb), pure Sn, 96Sn‐4Ag, and 77.2Sn‐20In‐2.8Ag solders decreased significantly with reflow time, while the eutectic SnBi and 95Pb‐5Sn solders showed a much smaller decrease. A large amount of intermetallic compounds was formed throughout the entire region of the solder cap for the eutectic SnPb, 96Sn‐4Ag, 95Pb‐5Sn, and 77.2Sn‐20In‐2.8Ag, mainly due to the high solubility of Au in these solders. Slow intermetallic compound growth was observed for the eutectic SnBi solder.

Microstructure evolution in Cu pillar/eutectic SnPb solder system during isothermal annealing

2009 ◽  
Vol 15 (5) ◽  
pp. 815-818 ◽  
Author(s):  
Byoung-Joon Kim ◽  
Gi-Tae Lim ◽  
Jaedong Kim ◽  
Kiwook Lee ◽  
Young-Bae Park ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Isothermal Annealing ◽  
Cu Pillar ◽  
Snpb Solder ◽  
Eutectic Snpb

Dominant Migration Element in Electrochemical Migration of Eutectic SnPb Solder Alloy

2006 ◽  
Author(s):  
Shin-Bok Lee ◽  
Ja-Young Jung ◽  
Young-Ran Yoo ◽  
Young-Bae Park ◽  
Young-Sik Kim ◽  
...  
Keyword(s):  
Solder Alloy ◽  
Electrochemical Migration ◽  
Snpb Solder ◽  
Eutectic Snpb

Morphology of wetting reactions of SnPb alloys on Cu as a function of alloy composition

1998 ◽  
Vol 13 (1) ◽  
pp. 37-44 ◽  
Author(s):  
C. Y. Liu ◽  
K. N. Tu
Keyword(s):  
Free Energy ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Driving Force ◽  
Alloy Composition ◽  
Wetting Angle ◽  
Compound Formation ◽  
Side Band ◽  
Intermetallic Compound Formation ◽  
Pure Sn

We have investigated the wetting angle, side band growth, and intermetallic compound formation of seven SnPb alloys on Cu ranging from pure Sn to pure Pb. The wetting angle has a minimum near the middle composition and increases toward pure Sn and pure Pb, but the side band growth has a maximum near the middle composition. The intermetallic compounds formed are Cu6Sn5 and Cu3Sn for the eutectic and high-Sn alloys, yet for the high-Pb alloys, only Cu3Sn can be detected. While no intermetallic compound forms between Cu and pure Pb, the latter nevertheless wets the former with an angle of 115°. The driving force of a wetting reaction, which may be affected by the free energy gain in compound formation, is discussed by assuming that rate of compound formation is fast.

Measurement of impact toughness of eutectic SnPb and SnAgCu solder joints in ball grid array by mini-impact tester

2008 ◽  
Vol 23 (5) ◽  
pp. 1482-1487 ◽  
Author(s):  
Yuhuan Xu ◽  
Shengquan Ou ◽  
K.N. Tu ◽  
Kejun Zeng ◽  
Rajiv Dunne
Keyword(s):  
Impact Toughness ◽  
High Speed ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Snagcu Solder ◽  
Snpb Solder ◽  
Impact Tester ◽  
Pull Tests ◽  
The Impact ◽  
Eutectic Snpb

The most frequent cause of failure for wireless, handheld, and portable consumer electronic products is an accidental drop to the ground. The impact may cause interfacial fracture of ball-grid-array solder joints. Existing metrology, such as ball shear and ball pull tests, cannot characterize the impact-induced high speed fracture failure. In this study, a mini-impact tester was utilized to measure the impact toughness and to characterize the impact reliability of both eutectic SnPb and SnAgCu solder joints. The annealing effect at 150 °C on the impact toughness was investigated, and the fractured surfaces were examined. The impact toughness of SnAgCu solder joints with the plating of electroless Ni/immersion Au (ENIG) became worse after annealing, decreasing from 10 or 11 mJ to 7 mJ. On the other hand, an improvement of the impact toughness of eutectic SnPb solder joints with ENIG was recorded after annealing, increasing from 6 or 10 to 15 mJ. Annealing has softened the bulk SnPb solder so that more plastic deformation can occur to absorb the impact energy.

Interfacial reaction and wetting behavior in eutectic SnPb solder on Ni/Ti thin films and Ni foils

1999 ◽  
Vol 86 (12) ◽  
pp. 6746-6751 ◽  
Author(s):  
P. G. Kim ◽  
J. W. Jang ◽  
T. Y. Lee ◽  
K. N. Tu
Keyword(s):  
Thin Films ◽  
Interfacial Reaction ◽  
Wetting Behavior ◽  
Snpb Solder ◽  
Eutectic Snpb
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