Dynamic measurements of the spreading of liquid metals in controlled atmospheres with {ital in} {ital situ} surface preparation and analysis
- Center for Solder Science and Technology, Sandia National Laboratories, Albuquerque, New Mexico 87185-0367 (United States)
A specially designed ultrahigh vacuum {ital in} {ital situ} surface analysis and wetting system has been constructed to study the spreading of liquid metal solders on carefully prepared and well-characterized solid substrates. The system consists of a standard ultrahigh vacuum surface analysis chamber linked to a reaction chamber for wetting or other experiments at pressures up to atmospheric. A sophisticated video system allows real-time monitoring of the spreading of the liquid metal through both side and top views. An infrared imaging system allows accurate remote temperature measurements. Sample surfaces are prepared and spreading experiments performed without intermediate exposure of the surfaces to the contaminating atmospheres. Solder spreading is performed under 50 Torr of highly purified helium gas to allow for adequate thermal coupling between the solder and the substrate. Initial studies have been completed for the spreading of pure tin solder on copper substrates in the absence of any fluxing agent. Three types of copper substrate surfaces were investigated in these experiments: the sputter-cleaned, air-exposed, and the as-received surface. Surface chemical analysis by x-ray photoelectron spectroscopy showed the air-exposed surface to consist of about 3 nm of Cu{sub 2}O, while the as-received surface consisted of about 8 nm of Cu{sub 2}O. The sputter-cleaned surface contained less than one monolayer (0.3 nm) of Cu{sub 2}O. Spreading experiments utilizing a linear temperature ramp show that pure tin solder spreads readily on oxidized copper surfaces at elevated temperatures. The initiation temperature for rapid tin spreading on the as-received copper surface was 325{degree}C. Decreasing the thickness of the oxide on the surface lowered the observed temperature for the initiation of spreading and increased the rate of spreading. On the sputter-cleaned copper surface, rapid solder spreading was observed immediately upon melting of the solder.
- OSTI ID:
- 278619
- Journal Information:
- Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 2 Vol. 67; ISSN 0034-6748; ISSN RSINAK
- Country of Publication:
- United States
- Language:
- English
Similar Records
Assessing the effect of surface roughness on the wetting of Cu and Pd by Sn/Pb solder
Design and characterization of a compact two-target ultrahigh vacuum magnetron sputter deposition system: Application to the growth of epitaxial Ti[sub 1[minus][ital x]]Al[sub [ital x]]N alloys and TiN/Ti[sub 1[minus][ital x]]Al[sub [ital x]]N superlattices