Solderability testing of Kovar with 60Sn40Pb solder and organic fluxes

Technical Report · Tue May 01 04:00:00 EDT 1990

DOI:https://doi.org/10.2172/6831383· OSTI ID:6831383

Vianco, P T; Hosking, F M; Rejent, J A

The solderability of 60Sn40Pb solder on Kovar was examined as a function of surface-cleaning procedure, flux, and solder-bath temperature. Organic-acid fluxes were more effective at lowering the contact angle than was a mildly activated, rosin-based (RMA) flux on chemically etched Kovar. The contact angles were as low as 29{degree} {plus minus} 5{degree} as compared to 61{degree} {plus minus} 11{degree}, respectively. Varying the solder temperature through the range of 215{degree}C to 288{degree}C caused an insignificant change in the contact angle for the RMA flux and a decrease of the contact angle for a candidate water-based, organic-acid flux. The dilution strength of the flux and the elapsed cleaning time significantly influenced the solder-flux interfacial tension, {sub {gamma}LF}. T-peel strengths of Kovar-60Sn40Pb-OFHC copper joints had a low correlation with the contact angle derived from the solderability experiments. The results of the solderability tests and the T-peel mechanical tests, and subsequence microanalysis of the as-soldered and T-peel samples revealed that the best results for the RMA flux were achieved by using an electropolishing procedure and a solder temperature of 240{degree}C to 260{degree}C. A relatively low contact angle of 31{degree} {plus minus} 2{degree} was observed, with no evidence of cracking or thick-film intermetallic formation at the Kovar-solder interface. T-peel strengths were nominally 9.4{degree} {plus minus} 0.5 {times} 10{sup 6} dyn/cm. 21 refs., 36 figs., 11 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: DOE/MA
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6831383
• Report Number(s): SAND-89-2345; ON: DE90013643
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CLEANING
COBALT ALLOYS
DILUTION
ETCHING
FABRICATION
IRON ALLOYS
IRON BASE ALLOYS
JOINING
JOINTS
KOVAR
LEAD ALLOYS
MANGANESE ADDITIONS
MANGANESE ALLOYS
NICKEL ALLOYS
SOLDERED JOINTS
SOLDERING
SURFACE CLEANING
SURFACE FINISHING
TEMPERATURE EFFECTS
TIN ALLOYS
TIN BASE ALLOYS
WELDING