Temperature rise and fusing current in wire bonds for high power RF applications

Abstract

Wire bonds in any semiconductor package represent an inductor between the die level bond pad and the lead fiame post. As current flows through the wire bond, there is some loss of power due to Joule's heating effect. This power is dissipated by means of conduction through the length of the wire, and convection and radiation from the surface of the wire. For DC applications, the fusing current of the wire is readily available. This study examines the phenomena as it applies to RF applications. In RF applications, the current is transmitted only through the outer layer (skin) of the conductor, and the skin depth is dependent on the frequency. A closed form solution is derived for a simplified case where both pad and post are at the same temperature. Analytical results were validated with the use of IR Scan measurements. A numerical solution methodology was also developed using couple field finite element method to account for both electrical and thermal loading. Fusing current predictions were obtained for 0 Hz (DC), as well as from 880 MHz to 2 GHz; which are frequencies of interest for cellular applications.The differences between analytical and experimental results were found to be less than 15% and between numerical and experimental results were found to be less than 10%.

Experimental characterization of wafer probe burn

“…The current constriction happens in the thin buckling beam section for vertical probes and at the tip section for cantilever probes. When an electrical current passes through a cantilever probe during the wafer level test, it heats the probe through a process known as Joule (or I 2 R) heating [5][6][7][8][9][10]. Joule heating is an energy dissipation phenomenon commonly observed in electrical current carrying conductors.…”

Line-spike induced failure mechanism in integrated circuit bond-wires

“…Catastrophic failure (opens) of wire bonds occurs when the local power dissipation in the wire exceeds critical levels which have been established by the selected circuit technology [1][2][3]. In this paper, a novel type of bond wire failure mechanism is described which results from voltage line spikes.…”