Contact resistance and shear strength of the solder joints formed using Cu bumps capped with Sn or Ag/Sn layer

Lee, Seung–Hyun; Roh, Hee-Ra; Chen, Huajun; Kim, Young‐Ho

doi:10.1007/s11664-005-0204-4

Cited by 16 publications

(7 citation statements)

References 10 publications

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“…The results of this study are in agreement with the results of Lee et al [22] who have found that the electrical resistance of solder Ag/Sn/Cu joints decreased, whereas their shear strength joints increased with the aging time.…”

Section: Discussionsupporting

confidence: 93%

Nanoscale Mechanical Properties of Intermetallics in Lead-Free Systems

Braunović

Gagnon

Rodrigue

2009

IEEE Trans. Comp. Packag. Technol.

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Bimetallic couples formed between commercially available lead-free alloys and selected contact materials were subjected to diffusion annealing using thermal gradients. Following diffusion annealing and aging, the contact interfaces were subjected to a detailed metallographic, scanning electron microscope (SEM), and energy dispersive X-ray (EDX) analyses. In addition, electrical resistance was used for electrical characterization of the intermetallics formed at the contact interfaces, whereas the nanoindentation technique was used to determine the nanoscale mechanical properties. An attempt was made to correlate the observed nanoindentation data with the microstructures of the intermetallic phases formed and electrical resistivity.

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Section: Discussionsupporting

confidence: 93%

Nanoscale Mechanical Properties of Intermetallics in Lead-Free Systems

Braunović

Gagnon

Rodrigue

2009

IEEE Trans. Comp. Packag. Technol.

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“…During cooling, a Cu 6 Sn 5 phase forms first in the Cu surface because the activation energy of the Cu 6 Sn 5 phase is lower than that of Cu 3 Sn IMC. [9][10][11]14 Typically, a Type I microstructure (Sn + Cu 6 Sn 5 ) is observed in the solder joints. When the liquid Sn is reacted with Cu at high temperature for a long time, Cu 3 Sn begins to form.…”

Section: Discussionmentioning

confidence: 99%

“…The shear strength of the solder joints was measured by shearing the test dies. 9,14 The microstructures of the solder joints before and after aging were analyzed using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS).…”

Section: Methodsmentioning

confidence: 99%

“…The number of microvoids forming along the interface between the Cu 3 Sn layer and the Cu layer increased as aging time continued. Fracture tends to follow the Cu/ Cu 3 Sn interface where many microvoids exist 9,14 since this interface is the weakest region. The shear strength of Type III specimens remained almost constant with aging since the microstructure (Cu 3 Sn only) did not change and microvoids did not form during aging.…”

Section: Chip To Chip Bonding Using Cu Bumps Capped With Thin Sn Layementioning

confidence: 99%

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Chip to Chip Bonding Using Cu Bumps Capped with Thin Sn Layers and the Effect of Microstructure on the Shear Strength of Joints

Kim

Woo

Kim

2014

Journal of Elec Materi

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Chip to chip bonding techniques using Cu bumps capped with thin solder layers have been frequently applied to 3D chip stacking technology. We studied the effect of joint microstructure on shear strength. Joints were formed by joining Sn/Cu bumps on a Si die and Sn/Cu layers on another Si die at 245-330°C using a thermo-compression bonder. Three different types of microstructures were fabricated in the joints by controlling the bonding temperature and time, (1) a Sn-rich phase with a Cu 6 Sn 5 phase at the Cu interfaces, (2) a Cu 6 Sn 5 phase in the interior with a Cu 3 Sn phase at the Cu interfaces, and (3) one single Cu 3 Sn phase throughout the whole joint. The joint having a single Cu 3 Sn phase had the highest shear strength. Specimens were aged up to 2000 h at 150°C and 180°C. During aging, the microstructures of all joints were transformed in a single Cu 3 Sn phase. The shear strength of the joints was very sensitive to the formation of Cu 3 Sn and microvoids. Microvoids formed in the solder joints with a Cu 6 Sn 5 phase with and without a Sn-rich phase during aging and decreased the shear strength of the joints. Conversely, aging did not induce the formation of microvoids in the joints which originally had only a Cu 3 Sn phase and the shear strength was not decreased.

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“…[ (4) A similar approach to hollow square model can be achieved. The maximum distance and minimum distance can be measured as shown in Figure 6.…”

Section: Quality Inspection Method: Torsion Test Screeningmentioning

confidence: 99%

Process Development for Heat Sink Attachment Using Thermally Conductive Liquid Adhesives

Cho

Allen

Nguyen³

et al. 2007

Twenty-Third Annual IEEE Semiconductor Thermal Measurement and Management Symposium

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Premature field failure of heat sink attachments is one of the most important concerns in the microelectronic packaging industry. In order to minimize failure problems, this study focused on the optimization of the heat sink attachment process and development of an adhesion inspection method. Acrylic-based liquid adhesives were selected for this study to deliver mechanical adhesion strength and high thermal performance of heat sink attachment. Optimal process conditions for volume, mounting pressure, and pressing time were obtained from volume consistency testing, torsion testing, and thermal resistance measurements.Failure analysis was conducted on fracture surfaces after torsion testing. Two failure modes were discovered: interface failure and bulk materials failure. Bond line thickness greater than 254 microns (10 mils), produced more materials failure, which caused reduction in torsion strength. Maximum strength and thermal performance were obtained using contact area of 50% or greater and bond line thickness of 203-254 microns (8-10 mils). Temperature cycling results will also be presented.Torsion test screening was selected to verify heat sink attachment integrity during real-time quality assurance. The torsion strength of a whole soldered package joint was calculated from the nominal shear strength of individual solder joints using the total area approximation. This calculated torsion strength for the package sets an upper limit to torsion testing values.

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Contact resistance and shear strength of the solder joints formed using Cu bumps capped with Sn or Ag/Sn layer

Cited by 16 publications

References 10 publications

Nanoscale Mechanical Properties of Intermetallics in Lead-Free Systems

Nanoscale Mechanical Properties of Intermetallics in Lead-Free Systems

Chip to Chip Bonding Using Cu Bumps Capped with Thin Sn Layers and the Effect of Microstructure on the Shear Strength of Joints

Process Development for Heat Sink Attachment Using Thermally Conductive Liquid Adhesives

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