Effect of Atmospheric Pressure Plasma Treatment on Transverse Ultrasonic Bonding of Gold Flip-Chip Bump on Glass Substrate

Abstract

This study was focused on the effect of atmospheric pressure plasma treatment conditions on the ultrasonic bonding properties of Au flip-chip bumps on Au-finished glass substrates. The spreading test of de-ionized (DI) water was carried out on the substrate after the treatment. The plasma treatment was performed with three different gases, N2, N2 + O2, and N2 + H2, for various treatment times from 0.3 to 18 s. The surface analysis was carried out after the treatment using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The treatment conditions greatly affected the spreading angle and joint strength. The addition of O2 and H2 gases to N2 gas was effective to improve the wettability of the Au-finished substrate and the bondability between the Au bump and substrate, respectively. The spreading angle rapidly decreased with increasing treatment time from 0.3 to 1 s and then decreased slightly with further increase in the treatment time, whereas the bonding strength peaked after the treatment for 0.5 to 2 s and then decreased.

Properties of various plasma surface treatments for low-temperature Au–Au bonding

“…Atmospheric-pressure (AP) plasma was applied to a pretreatment method before bonding, such as plasma activated bonding or ultrasonic bonding. [16][17][18][19] There are also some reports on Au-Au SAB using AP plasma. [20][21][22][23][24] By using AP plasma for surface activation, the entire bonding process including surface activation and bonding can be achieved in ambient air.…”

Room-Temperature Gold-Gold Bonding Method Based on Argon and Hydrogen Gas Mixture Atmospheric-Pressure Plasma Treatment for Optoelectronic Device Integration

“…In this paper, to realize a low-cost instrument and to improve productivity, atmospheric-pressure (AP) plasma, which has been successfully applied for a pretreatment method for ultrasonic bonding [17], [18], is applied to AuAu SAB. The entire bonding process, including surface activation, is carried out in ambient air.…”