Lead-free solders for electronics applications: Wetting analysis
Conference
·
OSTI ID:5494227
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
The fabrication of electronic systems has relied upon eutectic tin-lead solder for the attachment of components to printed wiring boards. Higher service temperatures are approaching the durability limits of the eutectic solder. The tin-rich, lead-free solders are being actively studied as alternate alloys. Experiments that examined the wettability of 95Sn-5Sb (wt. %), 95.5Sn-4.0Cu0.5Ag, 96.5Sn-3.5Ag, and the control solder, 60Sn-40Pb, on oxygen-free, high conductivity copper were performed. A rosin based, mildly activated (RMA) flux and three water soluble, organic acid fluxes were used in the wetting balance/meniscometer measurements. The 95.5Sn-4.0Cu-0.5Ag and 95Sn-5Sb alloys exhibited good wetting, with contact angles of 35° < θc < 55° as compared to the excellent performance of the 60Sn-40Pb material (20°< θc <35°). The fair wettability observed with the 96.5Sn 3.5Ag solder (60° < θc <75°) was due in large part to the inability of the fluxes to significantly lower the solder-flux interfacial tension. The wetting rates of the 95.5Sn-4.0Cu-0.5Ag and 95Sn 5Sb solders were comparable to those of the control; the 96.5Sn 3.5Ag alloy wetting rate was slower than the other candidates. The solder film formed on the substrate surface by the 95.5Sn-4.0Cu0.5Ag alloy was very grainy. The water soluble fluxes exhibited a larger degree of residue formation than did the RMA flux.
- Research Organization:
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5494227
- Report Number(s):
- SAND--91-0031C; CONF-9108110--1; ON: DE91014900
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
42 ENGINEERING
426000 -- Engineering-- Components
Electron Devices & Circuits-- (1990-)
ALLOYS
ANTIMONY ALLOYS
COPPER ALLOYS
ELECTRONIC EQUIPMENT
EQUIPMENT
JOINTS
LEAD ALLOYS
MICROSCOPY
OPTICAL MICROSCOPY
SOLDERED JOINTS
TIN ALLOYS
TIN BASE ALLOYS
WETTABILITY
360101* -- Metals & Alloys-- Preparation & Fabrication
42 ENGINEERING
426000 -- Engineering-- Components
Electron Devices & Circuits-- (1990-)
ALLOYS
ANTIMONY ALLOYS
COPPER ALLOYS
ELECTRONIC EQUIPMENT
EQUIPMENT
JOINTS
LEAD ALLOYS
MICROSCOPY
OPTICAL MICROSCOPY
SOLDERED JOINTS
TIN ALLOYS
TIN BASE ALLOYS
WETTABILITY