The gold solder, gold alloy interface

Mechanical properties of metal connectors soldered by gas torch versus an infrared technique

PURPOSE

The ultimate tensile strength and percentage elongation of solder joints of three alloy systems were tested.

MATERIALS AND METHODS

Solder joints were formed using either an infrared soldering machine or gas-oxygen torch. Intact solder materials were used as controls.

RESULTS

There were no significant differences in percentage elongation among different treatment methods of the solders or among various solder materials. All intact solder materials possessed significantly higher ultimate tensile strength than the joints made with either method. For high-noble and noble alloy solders, there were no significant differences in ultimate tensile strength of joints made with either method. For base metal alloy solder, the ultimate tensile strength of joints made with the infrared technique was significantly higher than that made with the gas-oxygen torch technique.

CONCLUSIONS

The infrared technique can be used as an alternative to the gas-torch technique for soldering high-noble and noble alloys. It is superior to the gas-torch technique for soldering a cobalt-chromium alloy.

Fatigue strength of a Au-Pd alloy/585 solder combination

The S-N diagram (applied stress vs. cycles to failure) for the gold-palladium alloy/585 solder combination was generated. Au-Pd alloy specimens were cast, prepared for soldering, and joined with 585 solder. After milling and polishing of the joint, testing was carried out in a specially designed machine. This device loaded the cantilevered test specimen in a unidirectional mode at a rate of 70 strokes per minute. The applied tensile stress ranged between 294.2 and 686.5 MPa. Three specimens were cycled for each stress level until fracture occurred. The number of fatigue cycles to failure ranged from one cycle (stress level, 686.5 MPa) to 4.83 x 10(6) cycles (stress level, 294.2 MPa). On a logarithmic scale, the relationship between the applied stress and the number of cycles to failure was linear. Under the present (ideal) experimental conditions, the Au-Pd/585 solder combination behaved favorably on the high-cycle end of the diagram. However, no definite endurance limit could be detected within the stress range examined.