Thermosonic gold-ball bond accelerated life test

Abstract

Accelerated aging tests on gold-ball bonds in hermetic packages have been conducted at 350 degrees C, 300 degrees C, 250 degrees C, and 200 degrees C to determine time to failure, activation energy of failure, and the electrical/mechanical degradation at failure. Four different aluminium/1% silicon metallizations were tested: evaporated metal with P-glass (passivation-glass) contamination, evaporated metal with no P-glass contamination, sputtered metal with P-glass contamination, and sputtered metal with no P-glass contamination. The measured activation energies were from 0.4 to 1.1 eV. Two failure modes were encountered; one was an electrical open with good mechanical strength, and the second was an electrical open that resulted from a premature ball lift caused by voiding under the ball bond. The projected time to failure using an Arrhenius plot indicated that the functional life of gold-ball bonds can exceed 20 yr at ambient temperature if the wire-bonder setup is optimized and the contamination level is low.<>