Stress relaxation behavior of composite and eutectic Sn-Ag solder joints

Jadhav, S. G.; Bieler, T. R.; Subramanian, K. N.; Lucas, J.

doi:10.1007/s11664-001-0150-8

Cited by 51 publications

(46 citation statements)

References 16 publications

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“…[10][11][12] When solder joints are subjected to thermal cycling during the operation of electronic systems, thermal strains are generated within the solder joint due to the coefficient of thermal expansion (CTE) mismatch between the solder and the substrate. The stress generated within the joint depends upon the value of the imposed thermal strain.…”

Section: Introductionmentioning

confidence: 99%

“…Solder joints operate at high homologous temperatures (>0.65 T m ) in the environment of electronic systems and could be subjected to thermal cycling from -50°C to 150°C (or even more) with dwell periods at the temperature extremes. 10 In order to assess the effect of dwell periods on the thermomechanical fatigue behavior of such solder joints, evaluation of the stress relaxation process is necessary.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Size Effects in Miniaturized Lead-Free Solder Joints

Zimprich

Saeed

Betzwar-Kotas

et al. 2007

Journal of Elec Materi

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Future reliability and quality control of microelectronics will greatly depend on a detailed understanding of the complex mechanical and thermal properties of miniaturized lead-free solder joints. Therefore, the question of the occurrence of size effects or dimensionally induced constraints, which could change the mechanical properties of solder joints in small dimensions dramatically, has become the focus of investigation. In this study we investigated the influence of decreasing gap size on the tensile, shear, and stress relaxation behavior of solder joints to investigate the occurrence of size effects and dimensionally induced constraints, which could change the mechanical properties of solder joints significantly in micrometer dimensions. Residual stresses might remain in the solder joints during high-temperature dwell in thermomechanical fatigue. Model solder joints (Sn3.5Ag/Cu) of rectangular shape with gap sizes varying between 25 lm and 850 lm were prepared by reflow soldering to achieve near-industrial soldering processing. Scanning electron microscopy was used for analyzing the microstructure and the complex modes of fracture and crack propagation in the solder interconnect. The observed tensile behavior can be interpreted in terms of an existing theory for brazed joints to complement finite-element analysis that is usually used for a description of these phenomena.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanical Size Effects in Miniaturized Lead-Free Solder Joints

Zimprich

Saeed

Betzwar-Kotas

et al. 2007

Journal of Elec Materi

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mentioning

confidence: 85%

“…The strong role of time and temperature performance, particularly, in lead-free solders. [8][9][10][11][12] above solder liquidus during reflow, especially Such solders may contain a IMC produced either by during the heating segment, in development of sun flower morphologies into blocky morphologies has been documented in an earlier study. 13 The goal of the present study was to compare the morphology of the IMC formed around the metallic reinforcements, Ag, Cu, and Ni, contained in the Sn-Ag solder so as to gain a better understanding of parameters that contribute to various IMC morphologies.…”

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confidence: 85%

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Formation and growth of intermetallics around metallic particles in eutectic Sn-Ag solder

Lee

Chen

Subramanian

2003

Journal of Elec Materi

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Incorporation of metallic particulate reinforcements in eutectic Sn-Ag solder re sults in the formation of intermetallic compounds (IMCs) along particulate/ solder interfaces with different morphologies. For instance, "sunflower" and "blocky faceted" IMC shapes have been observed around Ni particle reinforce ments incorporated in the eutectic Sn-Ag solder matrix. The time and tempera ture above solder liquidus during the heating stage of the reflow process has been found to play a significant role in determining the IMC morphology in these Ni particulate-reinforced solders. Similar studies were carried out with Cu and Ag particulate reinforcements using the same solder matrix. The amount of heat input caused no significant change in morphology of the IMCs formed around Cu and Ag particulate reinforcements. Also, the IMC morphol ogy around Ni particles was sensitive to the Cu content in the solder, whether the Cu came from the substrate during reflow or it was already present within the solder.Key words: Lead-free composite solder, intermetallic morphology, metallic particle reinforcements in-situ methods 8,9 or mechanically incorporated, INTRODUCTION metallic particles, which upon reflow completely or Intermetallic compounds (IMCs) formed both partially transform into IMCs. [10][11][12] Ternary and quaat the solder/substrate interface and within the ternary alloys being considered for enhanced service solder during reflow exhibit different morphological performance also derive their better attributes befeatures depending on the conditions employed. Sigcause of IMC particles present within the solder. nificant efforts have been devoted to characterize Significantly different morphologies of the IMC that solder/substrate interface IMCs. 1-5 The brittle naform around Ni particles present within the eutectic ture of IMCs formed at the solder/substrate inter-96.5Sn-3.5Ag (wt.%) solder matrix have been obface and their potential to degrade the mechanical served. These morphologies were dependent on the performance of the solder joints provides the main reflow conditions. 13 Incidentally, these morphologi impetus to study these compounds. However, it has cal features, which develop during reflow, will differ been clearly documented in several studies that between the reinforcements. 14,15 The Ni particlecatastrophic failure caused by thermomechanical reinforced solder showed change in the morphology fatigue or creep occurs by crack growth within the of the IMC around the Ni particles as a consequence solder near the solder/substrate interface, not in the of an imposed reflow profile. Depending on time and interface IMC layer. 6,7 temperature above solder liquidus during reflow, The composite solder approach has been demonsunflower or blocky morphology of the IMC was strated to be a viable means to achieve better service noted. The strong role of time and temperature performance, particularly, in lead-free solders. [8][9][10][11][12] above solder liquidus during reflow, especially Such solders may contain a IMC produced...

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