Welding characteristics and temperature rise of high frequency and complex vibration ultrasonic wire bonding

Abstract

Abstract Welding characteristics of 190 kHz ultrasonic wire bonding systems with linear, square and circular vibration loci are studied. High-frequency systems of 90 ~ 780 kHz were shown to be significantly effective compared with conventional frequency systems. The required vibration amplitude of high frequency becomes very small, i.e 0.04 μm (peak-to-zero value) at 780 kHz which is 1 30 that of 60 kHz [1–3]. Welding wire aluminum specimens 0.1 mm in diameter are joined successfully. The temperature rise at welding part is measured by thermoelectromotive force between aluminum wire and copper plate specimens, and deformation of wire specimens is measured by a height gage. Complex vibration welding tips of 190 kHz which vibrate in elliptical to circular or rectangular to square at the same or different frequencies are shown to be effective in joining welding specimens successfully in a shorter welding time and under smaller vibration amplitude, with a wider good welding domain. Temperature rise and wire deformation have a good correlation with weld strength obtained. With a high frequency longitudinal vibration system, it is very difficult to install a ceramic capillary at its tip because the dimensions of such high frequency systems as 330, 600 or 780 kHz become too small. For installing a ceramic capillary in the high frequency system, longitudinal to complex transverse vibration systems of 160 ~ 575 kHz are proposed and the vibration characteristics of the system and a ceramic capillary are measured. The capillary 1.5875 mm in diameter and 6.5 mm in projection length has one transverse vibration node along its length at 160 kHz and two vibration nodes at 515 kHz.