The cavitation characteristics at filler metal/substrate interface during ultrasonic-assisted soldering were first recorded by high-speed photography in this work. Two kinds of bubbles, steady cavitation bubbles and transient cavitation bubbles were observed. Steady cavitation bubbles did not collapse within one acoustic period and could last longer than 50 acoustic periods. Transient cavitation bubbles formed and collapsed within one acoustic period. The cavitation process was divided into two stages based on the cavitation characteristics. The first violent cavitation stage was in fact the degassing process, which lasted approximately 2700 acoustic periods and was affected by the gas content trapped inside the filler metal and the stronger vibration at the initiation stage of ultrasonic-assisted soldering. The second steady cavitation stage had obvious low bubble density and accounted for the most of the soldering process. Higher cavitation densities were observed when small channel width and large ultrasonic power were used because of larger sound pressures inside the filler metal.

在这项工作中，首先通过高速摄影记录了超声辅助焊接过程中填充金属/基材界面处的空化特性。观察到两种气泡，稳定的空化气泡和瞬时的空化气泡。稳定的空化气泡不会在一个声波周期内坍塌，并且可能会持续超过50个声波周期。瞬态空化气泡在一个声波周期内形成并坍塌。根据空化特性，将空化过程分为两个阶段。实际上，第一个剧烈的气蚀阶段是脱气过程，该过程持续了大约2700个声波周期，并受困在填充金属内部的气体含量以及超声辅助焊接开始阶段的较强振动的影响。第二个稳定的空化阶段具有明显的低气泡密度，并且占焊接过程的大部分。当使用较小的通道宽度和较大的超声波功率时，由于填充金属内部的声压较大，因此观察到较高的空化密度。