Deformation of PbSn eutectic alloys at relatively high strain rates

Superplastic creep of eutectic tinlead solder joints

“…This superplasticity was attributed to the stable, equiaxed microstructure that results from recrystallization at room temperature. Others [5][6][7][8][9][10][11][12][13][14][15][16][17][18] have explored the dependence of superplasticity in cold-worked Sn-Pb alloys on variables, such as testing temperature, grain size, stress, and strain rate. In contrast to the extensive studies on the cold-worked and recrystallized Sn-Pb alloys, little attention has been paid to the alloys in the as-cast condition, beyond the repeated observation that as-cast alloys are not superplastic 3,4,6,19. But the recent works by Solomon 20, and by Seyyedi, Arsenault, and Keller 21 have shown that as-solidified solder joints exhibit some superplastic characteristics: the stress exponent, n, in the relation, ' Y = A cr 0 , is between 2 and 3 in a certain strain rate range.…”

Creep in Shear of Experimental Solder Joints

“…This recrystallized Pb-Sn is known to go through several deformation regimes, each subject to different rate controlling mechanisms and each with a characteristic value of the stress exponent and activation energy. Within the strain rate/stress/temperature regime studied in this work, a recrystallized Pb-Sn microstructure is expected to behave superplastically with a characteristic stress exponent -2 and an activation energy equal to that of grain boundary diffusion, 12 kcaVmole (Bird et al, 1964;Zehr and Backhofen, 1968;Mohamed and Langdon, 1975;Grivas et al, 1978 and1979;Murty, 1981 and1982). Additionally, superplastic creep occurs without a primary creep regime.…”

“…Bulk eutectic Pb-Sn samples are known to behave according to this equation. Specifically, deformation in the conventional climb-controlled creep regime is characterized by a stress exponent of 6-7 and an activation energy equal to -20 kcai/mole (Zehr and Backhofen, 1968;Grivas et al, 1979;Rohde and Swearengen, 1980;Kashyap and Murty, 1982;Weinbell et al, 1987)· However, it should be made clear that different deformation mechanisms, and hence different n and Ea values, are possible with different microstructures within this single alloy system. For example, a worked and annealed, i.e.…”

Dynamic Mechanical Properties and Microstructural Studies of Lead‐Free Solders in Electronic Packaging

“…The emphasis has been on areas such as product-level tests [7,8], boardlevel tests, simulation involving drop tests [9][10][11], bending tests [12,13], thermomechanical effects [11,14,15], low-strain-rate tensile properties [15][16][17], creep and stress relaxation [18][19][20][21], vibration [22,23], and microstructure [19,20,24].…”

“…However, experiments have always been conducted at relatively low strain rates. There have been several reports on the range of strain rates that solder interconnects experience during drop experiments: 1 × 10 −5 to 1 × 10 −3 sec −1 by Wei et al [15], 2.66 × 10 −5 to 1.33 × 10 −2 sec −1 by Grivas et al [16], and 1 × 10 −5 to 0.1 sec −1 by Nose et al [17]. During drop impact scenarios, solder joints experience deformation at high strain rates; consequently, the high-strain-rate response of solder material is needed.…”