Interfacial stability of eutectic SnPb solder and composite 60Pb40Sn solder on Cu/Ni(V)/Ti under-bump metallization

Eutectic SnPb solder has been widely used in packaging for several decades. The stability of the interface between solder and under-bump metallization (UBM) is an important issue that has led to many studies. Even though Ni atoms dissolve much slower into SnPb solder than Cu, the intermetallic compound, Ni3Sn4, which forms when eutectic SnPb solder reacts with Ni(V)/Ti UBM, is not stable on Ti layer, creates V-rich zone, and causes spalling. To prevent the phenomenon, and the resulting reduction of mechanical reliability in solder joints, we propose the addition of a layer of Cu thin film to serve as a sacrificial layer. Both eutectic SnPb solder and composite solder (high-Pb solder with eutectic SnPb solder) were studied in severe reflow conditions to simulate the worst case of die attach and later reflow process. Cu film first was consumed completely to form a compound. Due to lower interfacial energy between Cu6Sn5 and Ni(V), the interface was stable and no spalling occurred. However, the same thickness of Cu was insufficient to prevent Ni from diffusing into solder or compound. Not only diffusion of Ni atoms was observed; Sn atoms also diffused into the Ni(V) layer. The Sn–Ni reaction caused the interface between the compound and Ni(V) to retreat into the Ni(V) layer. The compound was not stable at the interface, and spalling could be seen. Due to the interdiffusion of Ni and Sn, many Kirkendall voids were also observed at both side of the interface.

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Microstructure Studies of Under Bump Metallization Systems Using Transmission Electron Microscopy

ISTFA 2002: Conference Proceedings from the 28th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2002p0505 ◽

2002 ◽

Author(s):

Chih-Hang Tung ◽

Poi-Siong Teo ◽

Marvin C.Y. Lo ◽

George T.T. Sheng

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Sample Preparation ◽

Under Bump Metallization ◽

Interface Reactions ◽

Bonding System ◽

Transmission Electron ◽

Snpb Solder ◽

Ball Bonding ◽

Eutectic Snpb

Abstract In this study, the interface reactions between eutectic SnPb solder and two Ni-based UBM systems are reported, namely the sputtered Cu/Ni(V)/Al and the electroless Au/Ni(P) systems. Comparisons are made to the conventional Au/Al ball bonding system in terms of microstructure evolution, and metallurgical stability. TEM sample preparation is critical in this analysis. The capability of TEM in UBM microstructure studies is demonstrated.

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Microstructure evolution during electromigration in eutectic SnPb solder bumps

Journal of Materials Research ◽

10.1557/jmr.2004.0305 ◽

2004 ◽

Vol 19 (8) ◽

pp. 2394-2401 ◽

Cited By ~ 3

Author(s):

C.M. Lu ◽

T.L. Shao ◽

C.J. Yang ◽

Chih Chen

Keyword(s):

Failure Mechanism ◽

Microstructural Evolution ◽

Microstructure Evolution ◽

Under Bump Metallization ◽

Current Stressing ◽

Solder Bumps ◽

Snpb Solder ◽

Cathode Substrate ◽

Anode Substrate ◽

Eutectic Snpb

A technique has been developed to facilitate analysis of the microstructural evolution of solder bumps after current stressing. Eutectic SnPb solders were connected to under-bump metallization (UBM) of Ti/Cr-Cu/Cu and pad metallization of Cu/Ni/Au. It was found that the Cu6Sn5 compounds on the cathode/chip side dissolved after the current stressing by 5 × 103 A/cm2 at 150 °C for 218 h. However, on the anode/chip side, they were transformed into (Nix,Cu1-x)3Sn4 in the center region of the UBM, and they were converted into (Cuy,Ni1-y)6Sn5 on the periphery of the UBM. For both cathode/substrate and anode/substrate ends, (Cuy,Ni1-y)6Sn5 compounds were transformed into (Nix,Cu1-x)3Sn4. In addition, the bumps failed at cathode/chip end due to serious damage of the UBM and the Al pad. A failure mechanism induced by electromigration is proposed in this paper.

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Measurement of electromigration activation energy in eutectic SnPb and SnAg flip-chip solder joints with Cu and Ni under-bump metallization

Journal of Materials Research ◽

10.1557/jmr.2010.0230 ◽

2010 ◽

Vol 25 (9) ◽

pp. 1847-1853 ◽

Cited By ~ 7

Author(s):

Hsiao-Yun Chen ◽

Chih Chen

Keyword(s):

Activation Energy ◽

Flip Chip ◽

Void Formation ◽

Under Bump Metallization ◽

Solder Bumps ◽

Snpb Solder ◽

Snag Solder ◽

Temperature Coefficient Of Resistivity ◽

Eutectic Snpb ◽

Real Temperature

Electromigration activation energy is measured by a built-in sensor that detects the real temperature during current stressing. Activation energy can be accurately determined by calibrating the temperature using the temperature coefficient of resistivity of an Al trace. The activation energies for eutectic SnAg and SnPb solder bumps are measured on Cu under-bump metallization (UBM) as 1.06 and 0.87 eV, respectively. The activation energy mainly depends on the formation of Cu–Sn intermetallic compounds. On the other hand, the activation energy for eutectic SnAg solder bumps with Cu–Ni UBM is measured as 0.84 eV, which is mainly related to void formation in the solder.

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

Metals and Materials International ◽

10.1007/s12540-009-0815-4 ◽

2009 ◽

Vol 15 (5) ◽

pp. 815-818 ◽

Cited By ~ 9

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

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Dominant Migration Element in Electrochemical Migration of Eutectic SnPb Solder Alloy

56th Electronic Components and Technology Conference 2006 ◽

10.1109/ectc.2006.1645714 ◽

2006 ◽

Cited By ~ 1

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

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Parametric Analysis of Slope Stability for River Embankment

Journal of Advanced Engineering and Computation ◽

10.25073/jaec.202043.291 ◽

2020 ◽

Vol 4 (3) ◽

pp. 196

Author(s):

Dhrubo Haque ◽

Md Isteak Reza

Keyword(s):

Slope Stability ◽

Soil Property ◽

Failure Surface ◽

Worst Case ◽

Creative Commons ◽

Stability Of Slope ◽

The Stability ◽

Underlying Soil ◽

Open Access Article ◽

Stiff Soil

This paper has aimed to investigate the slope stability for various conditions like embankment geometry, water level and soil property. The analysis has been performed by using the XSTABL program for different slope heights, slope angles and flood conditions with a fixed soil cohesion value. Since the rapid drawdown is the worst case for a particular embankment therefore, the analysis has been further performed with different cohesion values. From this investigation it has been noticed that the increase of cohesion of soil can increase the stability to a great extent. All the analysises have been performed for twenty bore logs. It has been found that the underlying soil affects the stability of slope as the failure surface intersects the soil of this region. It has been also observed that the loose, liquefiable sandy soil decreases the stability while the stiff soil with sufficient cohesion value stabilizes the slope of embankment. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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Using Financial Instruments

Capital Markets, Derivatives, and the Law ◽

10.1093/oso/9780190879631.003.0004 ◽

2019 ◽

pp. 37-46

Author(s):

Alan N. Rechtschaffen

Keyword(s):

Financial Market ◽

Capital Markets ◽

Federal Reserve ◽

Financial Instruments ◽

Case Scenario ◽

Worst Case ◽

Financial Instrument ◽

Market Participants ◽

Managing Risk ◽

The Stability

Capital markets provide enterprises with the opportunity to access capital to maintain their level of business activity. Therefore, ensuring the stability of the capital markets and preventing systemic failure are paramount concerns of the Federal Reserve and other financial market regulators. Access to capital markets is facilitated through the use of financial instruments that allow risk to be negotiated among market participants. When using financial instruments to achieve goals, a corporation must be aware of several considerations: the value of the asset underlying the financial instrument, duties or obligations the corporation owes to the other party to the contract, the implications and “worst case scenario” of the performance of the financial instrument, the risk of the transaction, and how the specific transaction can achieve the corporation's goals. This chapter discusses goal-oriented investing, achieving investment goals, and managing risk.

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Characteristics of the Electroless-Deposited Cu Film as Interconnect on a TaN Diffusion Barrier

Materials Science Forum ◽

10.4028/www.scientific.net/msf.449-452.681 ◽

2004 ◽

Vol 449-452 ◽

pp. 681-684

Author(s):

Jung Sik Kim

Keyword(s):

Thin Film ◽

Diffusion Barrier ◽

Annealing Temperature ◽

Intermediate Compound ◽

Multilayered Structure ◽

Good Adhesion ◽

Post Heat Treatment ◽

Cu Film ◽

Cu Thin Film ◽

Thermal Stability Of

In the present study, thermal properties of the electroless-deposited Cu thin film were investigated. The Cu thin film of good adhesion was successfully deposited on the TaN barrier layer by a electroless deposition method. The multilayered structure of Cu/TaN/Si was prepared by electroless-depositing the Cu thin layer on the TaN diffusion barrier which was deposited by MOCVD on the Si substrate. In order to investigate the effect of post-heat treatment the specimen was annealed in H2 reduction atmosphere. Crystallization and agglomeration of the electroless-deposited Cu film occurred through annealing at H2 atmosphere and resulted in the decrease of film resistance. Thermal stability of Cu/TaN/Si system was maintained up to the annealing temperature of 600°C in H2 atmosphere above which the intermediate compound of Cu-Si was formed through diffusion into the TaN layer

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

Journal of Materials Research ◽

10.1557/jmr.2008.0186 ◽

2008 ◽

Vol 23 (5) ◽

pp. 1482-1487 ◽

Cited By ~ 9

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.

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