Wetting phenomena on ultrasonic soldering of aluminum

Abstract

Effects of ultrasonic on capillary penetration of a solder, effects of oxide film thickness on the base metal on solderability and a relation between the output power and the wet area on a single sheet were examined. Al-1200 sheets 0.5mm in thickness were soldered at 420°C using a 95%Zn-5%Al soldering alloy and a 20kHz ultrasonic soldering equipment. The ultrasonic soldering is applicable to a wider gap than the conventional soldering. When the sheets are soldered at a capillary gap, an upper part of soldered joint is incompletely joined showing apparent wetting. If the dipped sheet is single one, no apparent wetting is found. The thicker the oxide film, the wider the part of apparent wetting. The wet area on the single sheet is in accordance with a logarithmic law in relation to the dipping time.