Rapid Solidification of Sn-Cu-Al Alloys for High-Reliability, Lead-Free Solder: Part I. Microstructural Characterization of Rapidly Solidified Solders
Particles of Cu x Al y in Sn-Cu-Al solders have previously been shown to nucleate the Cu 6Sn 5 phase during solidification. In this study, the number and size of Cu 6Sn 5 nucleation sites were controlled through the particle size refinement of Cu x Al y via rapid solidification processing and controlled cooling in a differential scanning calorimeter. Cooling rates spanning eight orders of magnitude were used to refine the average Cu x Al y and Cu 6Sn 5 particle sizes down to submicron ranges. The average particle sizes, particle size distributions, and morphologies in the microstructures were analyzed as a function of alloy composition and cooling rate. Deep etching of the samples revealed the three-dimensional microstructures and illuminated the epitaxial and morphological relationships between the Cu x Al y and Cu 6Sn 5 phases. Transitions in the Cu 6Sn 5 particle morphologies from faceted rods to nonfaceted, equiaxed particles were observed as a function of both cooling rate and composition. Initial solidification cooling rates within the range of 10 3 to 10 4 °C/s were found to be optimal for realizing particle size refinement and maintaining the Cu x Al y /Cu 6Sn 5 nucleant relationship. In addition,more »
- Authors:
-
[1];
[2];
[2];
[1]
- Purdue Univ., West Lafayette, IN (United States)
- Ames Lab. and Iowa State Univ., Ames, IA (United States)
- Publication Date:
- Report Number(s):
- IS-J-9157
Journal ID: ISSN 1073-5623; PII: 3738; TRN: US1801048
- Grant/Contract Number:
- AC02-07CH11358
- Type:
- Accepted Manuscript
- Journal Name:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
- Additional Journal Information:
- Journal Volume: 47; Journal Issue: 12; Journal ID: ISSN 1073-5623
- Publisher:
- ASM International
- Research Org:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Org:
- USDOE
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; intermetallics; rapid-solidification; quenching; microstructure; metallography; scanning electron microscopy; SEM
- OSTI Identifier:
- 1417369