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Creep behavior of the ternary 95.5Sn-3.9Ag-0.6Cu solder—Part I: As-cast condition

“…11: † dε/dt min = B (σ) n exp (Ϫ∆H/RT) (11) A phenomenon that is commonly observed with this analysis format is power-law breakdown. At low stresses, typically Ͻ10 MPa in the case of solders, the value of n is in the range of 3-5.…”

“…where dε 11 /dt is the inelastic strain rate (s Ϫ1 ); σ 11 is the applied stress (MPa); B 11 and D are the state variables of non-isotropic back stress and the isotropic strength, respectively; f o (1/MPa-s) and β (no units) are constants; Q is the apparent-activation energy (J/mol); T is temperature (K); R is the universal gas constant (8.314 J/mol-K); and m is the "sinh-law" exponent (no units). The subscript 11 denotes the uniaxial case.…”

“…dD/dt ϭ (A 1 |dε p 11 /dt|)/(D Ϫ D o ) A3 Ϫ A 2 (D Ϫ D o ) 2 (2) dB 11 /dt ϭ (A 4 |dε p 11 /dt|)/|B 11 | A6 Ϫ A 5 B 11 |B 11 (3) The parameter ε p represents the time-independent, equivalent plastic strain. The computational model is combined with a finite-element mesh to map the deformation (rate) throughout the solder joint geometry.…”

A Novel Mechanism of Embrittlement Affecting the Impact Reliability of Tin-Based Lead-Free Solder Joints

“…This has been reported for both Sn-based and Sn-Pb solders tested at intermediate strain rates (10 À3 s À1 to 10 À1 s À1 ) and moderately low temperatures (>À40°C). 22,24 It has also been reported for Sn-Pb solders tested at truly dynamic conditions (strain rates $500 s À1 to 3000 s À1 ). 4,23 Interestingly, one of these studies even reported a ductile-to-brittle transition for the Sn-37%Pb solder at RT as the applied strain rate increased from 450 s À1 to 2720 s À1 during split Hopkinson pressure bar tests.…”

“…5,7,9,[12][13][14][15][16][17] Numerous investigations have already been conducted in order to assess the impact reliability of Sn-based solders mostly in comparison with that of Sn-Pb solders. Only two of these studies investigated the response of Sn-based solders to dynamic loading at low temperatures: one applied tension at intermediate strain rates (10 À3 s À1 to 10 À1 s À1 ) on Sn-0.5%Cu and Sn-3.5%Ag bulk specimens at À10°C, 24 and the other subjected SAC 101 solder joints to high-speed cyclic bend tests at À10°C 10 ; the latter reported a change in the joint failure from ductile at room temperature (RT) to brittle at À10°C. The rest of the studies focused on the room-temperature impact reliability of Sn-based solders, using in most of the cases truly dynamic strain rates.…”