Reliability and characterization of MLC decoupling capacitors with C4 interconnections

Abstract

Multilayer ceramic (MLC) capacitors are composite structures made of alternating layers of ceramic (dielectric material) and metal (electrodes). The dielectric material is barium titanate-based ceramic and the electrodes are made of platinum. C4 (controlled collapse chip connections) technology is used to provide multiple attachment points to substrates. A high dielectric constant of barium titanate-based ceramic helps to achieve a large capacitance/size ratio. The capacitance ranges from 32 nF to 100 nF in body sizes up to 1.85/spl times/1.6/spl times/0.85 mm. In this paper, we cover design, reliability and electrical characterization of capacitors with C4 interconnections. Reliability stress tests performed during qualification were designed to cover a wide range of field applications and included stress tests such as liquid to liquid thermal shock, moisture resistance and thermal cycles per Mil.Std., high temperature bias, temperature humidity bias and tensile pull. A visual inspection of parts post stress and physical analysis of unstressed parts were also performed. The parameters monitored during stress testing were: capacitance, leakage current and plate resistance. The electrical characterization measurements included effects of frequency, temperature and voltage. Inductance measurements were included based on a self-resonance technique.