Elevated-Temperature Mechanical Properties of Lead-Free Sn-0.7Cu-xSiC Nanocomposite Solders

Boron Nitride Nanotubes Modified on a Lead-Free Solder Alloy for Microelectromechanical Packaging

“…Other reports by Shen et al and Jung et al show similar findings. ,, An enhancement in elongation of B-SAC alloys is related to the slipping-mode transition induced by the BNNTs that relies on the interaction of BNNTs at the interface . Due to the finer BNNTs (∼20 nm), the shear deformation changed from dislocation–BNNT shearing to dislocation–BNNT glide . Therefore, the result of this work presents a future scope of BNNT-reinforced robust interconnect materials for microelectronic devices.…”

“…The shear yield strength of the B-SAC composite alloys can be expressed as where σ composite and σ matrix are the shear yield strength of the composite and the pristine SAC sample, respectively, , and Δσ is the enhanced fraction of shear strength, which depends on the various operating mechanisms of strengthening. − Dislocation multiplication term due to the thermal-elastic mismatch where Δ T is (process temperature – test temperature). Since, the homologous temperature ( T h > 0.5 T m , T m = melting point) of SAC305 is high, the mechanical performance will vary according to the temperature. − The large secondary phases (Ag 3 Sn, Cu 6 Sn 5 ) no longer block the dislocations, and the creep effects diminish with the time duration at high temperatures. − Orowan strengthening and Grain size (Hall–Petch equation) Additionally, load-transfer occurring from the SAC305 matrix to BNNTs contributes to the tensile–shear, as follows. Load-carrying ability of BNNTs In the above equations, β and k y are constants; G m and b are matrix shear modulus and Burgers vector, respectively; V P and d P are fraction and size of the BNNTs, respectively; d m is the β-Sn grain size; σ mo is the yield strength of pristine SAC305; Δα is the mismatch in thermal expansion coefficient between SAC305 and BNNTs. The data and calculated strengthening contributions are given in Supporting Table S2. − The calculated strength showed an improvement of 13.34 MPa at room temperature over the pristine SAC305 matrix as depicted by eq .…”

“…Dislocation multiplication term due to the thermal-elastic mismatch where Δ T is (process temperature – test temperature). Since, the homologous temperature ( T h > 0.5 T m , T m = melting point) of SAC305 is high, the mechanical performance will vary according to the temperature. − The large secondary phases (Ag 3 Sn, Cu 6 Sn 5 ) no longer block the dislocations, and the creep effects diminish with the time duration at high temperatures. − …”

“…24 Due to the finer BNNTs (∼20 nm), the shear deformation changed from dislocation−BNNT shearing to dislocation−BNNT glide. 67 Therefore, the result of this work presents a future scope of BNNT-reinforced robust interconnect materials for microelectronic devices.…”

Effect of Multiple Reflows on the Interfacial Reactions and Mechanical Properties of an Sn-0.5Cu-Al(Si) Solder and a Cu Substrate

“…Therefore, research on the formation and growth of IMC layers in multiple reflows or thermal aging environments is essential [ 16 , 17 ]. In this regard, studies have been conducted to improve microstructures and mechanical properties by adding small amounts of trace elements to Sn-Cu solder with relatively high melting points [ 18 , 19 , 20 , 21 , 22 ]. The addition of trace elements can reduce the diffusion velocity of IMCs by lowering the activity of Cu and Su elements or by blocking the diffusion path of atoms in liquid–solid reaction conditions [ 23 , 24 ].…”