Morphologies, orientation relationships and evolution of Cu6Sn5 grains formed between molten Sn and Cu single crystals (original) (raw)
Related papers
Acta Materialia, 2008
The morphologies and orientation relationships of Cu 6 Sn 5 grains formed between Sn and (0 0 1), (0 1 1), (1 1 1) and (1 23) Cu single crystals under liquid-and solid-state aging conditions were systematically investigated. The regular prism-type Cu 6 Sn 5 grains formed on (0 0 1) and (1 1 1) Cu single crystals are elongated either along two perpendicular directions or along three preferential directions with an angle of 60°between each pair of directions. The orientation relationships between Cu and Cu 6 Sn 5 lattice structures were determined by electron backscatter diffraction and were explained in terms of their minimum misfit. However, on (0 1 1) and (1 2 3) Cu single crystal surfaces, the Cu 6 Sn 5 grains were mainly scallop-type, with only a few regular prism-type grains. Furthermore, the regular prism-type Cu 6 Sn 5 grains will change into scallop-type after long reflow or aging times. Meanwhile it is considered that the growth of the scallop-type grains is supplied by two fluxes: the flux of the interfacial reaction and the flux of ripening. However, the growth of the prism-type grains is only supplied by the flux of the interfacial reaction. The kinetics of IMCs growth between Sn and Cu single crystals was also investigated.
Electronic Packaging Technology …, 2009
During the reflowing procedure, the Cu concentration in the solder affects the coarsening mechanisms of intermetallic compound (IMC) grains. For the Sn3Cu solder, the mean radius of the IMC grains was proportional to the cube root of the reflowing time; while it follows the square root relation with the reflowing time for the SnAgCu and Sn solders. It is proposed that the flux from the substrate was only consumed to coarsen the IMC grains for Sn3Cu solder, while it was separated into two fluxes for the SnAgCu and Sn solders at the reflowing initial procedure. For the Sn3.8Ag0.7Cu/Cu and Sn/Cu couples, the size distribution of the IMC grains well agrees with the modified flux driven ripening (FDR) model when the value of r/ r is above 1; while it would closely match with Marqusee and Ross analysis when the value of r/ r is below 1. For Sn3Cu/Cu couple, the size distribution of IMC grains shows good agreement with the FDR model. However, for SnPb/poly-Cu, during the solid-state aging procedure, the mean radius of the IMC grains was proportional to the cube root of the aging time. And the size distribution of IMC grains is well consistent with the FDR model.
Significant effect of orientation on Cu6Sn5 coarsening behavior in isothermal aging process
Journal of Materials Science: Materials in Electronics, 2020
Intermetallic compound (IMC) formed on (001) and (111) Cu single crystal has strong orientation and texture characteristics. The special interface morphology and uniform orientation provide a direction for the regulation of IMC growth behavior. In this study, the significant effect of orientation on Cu 6 Sn 5 growth behavior in isothermal aging process was investigated. Synchrotron radiation technology and high pressure air blowing methods were employed to obtain the growth kinetics and the morphology of Cu 6 Sn 5 during the heat preservation stage. The results indicate that scallop-like Cu 6 Sn 5 grains were formed in heat preservation stage. These grains exhibited an abnormal coarsening behavior that their average diameter at a high temperature of 300°C was smaller than that at a low temperature of 250°C after aging for 30 min. Besides, the growth orientation and kinetic controlling factor of these interfacial Cu 6 Sn 5 also changed with the increase of reaction time, which was closely related to the appearance of the abnormal coarsening phenomenon. These results are significant and meaningful to the electronic packaging industry.
2009
It is found that the morphologies and orientations of Cu 6 Sn 5 can be well controlled through designing orientations of Cu single crystal substrates. On and Cu single crystals, Cu 6 Sn 5 grains display regular prism-type morphology and align either along two perpendicular directions or along three directions having an angle of 60° between each other. By electron backscatter diffraction (EBSD) method, the preferred orientations of the Cu 6 Sn 5 grains are determined to strongly depend on the orientations of the Cu single crystals.
Structural evolution in the solidification process of Cu–Sn alloys
Journal of Non-crystalline Solids, 2007
The liquid structures in the solidification process of the Cu 100Àx Sn x (x = 10, 20, 30, 40) alloys were investigated by X-ray diffraction method. The results show that the Cu 3 Sn and quasi Cu 3 Sn structures exist in the Cu-Sn liquids. Which arouses an obvious structure change indicated by the correlation radius r c at about 900°C. In addition, the structure change induced by the liquid-solid transition at about 30-40°C below the liquidus is also observed.
A study of precipitation in a Cu15 wt%Ni8 wt%Sn alloy
Journal of Materials Science Letters, 1999
The precipitation sequence in Cu-Ni-Sn alloys has been studied in several works . The results of these works have shown that the phase separation occurs spinodally in the early stage of the aging process. The decomposed phases are Sn-rich (α 1 ) and Sn-lean (α 2 ) phases, which have been reported difficult to be analyzed by transmission electron microscope (TEM) . Furthermore, it has been reported that the spinodal decomposition in a Cu-15 wt %Ni-8 wt %Sn alloy occurred only at aging temperatures below 723 K [3]; however, this result was concluded from samples aged for times as long as 10 min. This aging time seems to be too long to study the spinodal decomposition at the early stages, which may take place even during the quenching of solution treated samples. The purpose of this work is to study the early stages of phase separation in a Cu-15 wt %Ni-8 wt %Sn alloy aged at 673, 773 and 873 K for different periods of time, using X-ray diffraction analysis, as well as a field ion microscope, FIM, which has been shown to be an effective tool to study the phase separation at an early stage in different alloy systems.
Computational Materials Science, 2011
Computational investigations of the morphological evolution and growth kinetics for intermetallic compounds (IMCs, Cu 6 Sn 5 and Cu 3 Sn) formed during reaction and aging between Sn-based solder and a copper substrate are presented. Cu-substrate, Cu 3 Sn (e phase) and Cu 6 Sn 5 (g phase) layers (or grains), as well as the Sn-liquid phase (or Sn-solid phase) are considered during the soldering (solid-state aging) process. In the simulation, interface regions are defined by the coexistence of two or more phases (at triple points) at a computational grid point. The simulation is performed through the multiphase-field approach. In the phase-field simulation, the grain boundary (GB) diffusion of the g phase as well as the interfacial energy between this phase and the solder alloy are treated as model parameters. Variation of these parameters allows the investigation of the effects of short-circuit diffusion paths and GB wetting on the morphological evolution of the IMC layers. The simulations addresses the growth kinetics of the two IMC layers (Cu 6 Sn 5 and Cu 3 Sn) during the two processes up to 14 h, illustrating the variation of g and e IMC thickness and the number of g and e grains as the microstructure coarsens.
Materials Chemistry and Physics, 2011
During the reflowing procedure, the Cu concentration in the solder affects the coarsening mechanisms of intermetallic compound (IMC) grains. For the Sn3Cu solder, the mean radius of the IMC grains was proportional to the cube root of the reflowing time; while it follows the square root relation with the reflowing time for the SnAgCu and Sn solders. It is proposed that the flux from the substrate was only consumed to coarsen the IMC grains for Sn3Cu solder, while it was separated into two fluxes for the SnAgCu and Sn solders at the reflowing initial procedure. For the Sn3.8Ag0.7Cu/Cu and Sn/Cu couples, the size distribution of the IMC grains well agrees with the modified flux driven ripening (FDR) model when the value of r/ r is above 1; while it would closely match with Marqusee and Ross analysis when the value of r/ r is below 1. For Sn3Cu/Cu couple, the size distribution of IMC grains shows good agreement with the FDR model. However, for SnPb/poly-Cu, during the solid-state aging procedure, the mean radius of the IMC grains was proportional to the cube root of the aging time. And the size distribution of IMC grains is well consistent with the FDR model.