The battle for maximum volumetric efficiency - Part 2: Advancements in solid electrolyte capacitors

Increasing need for capacitors with higher capacitance per unit volume has led to development efforts resulting in impressive combinations of dielectric thickness, dielectric constant and active area per unit volume. In order to achieve these developments, traditional Ta capacitor and multilayer ceramic capacitor (MLCC) technologies have evolved to surprisingly high levels of sophistication. These efforts have resulted in substantial increases in capacitance volumetric efficiency (VE_C) over time; rates that rival or exceed the rate of Moore's law for integrated circuit (IC) advancement.¹ In order to continue along this path, both valve conductor (e.g. Ta) and MLCC technologies face major challenges. This paper discusses these challenges from both materials and packaging developments perspectives. High VE_C-enabling technologies for traditional solid electrolyte capacitors are discussed, as well as a new, high dielectric constant (ε'), hybrid dielectric technology for electrolytic capacitor systems. Both development approaches have the potential to increase VEC several-fold for future capacitor devices and have the potential to be used in combination to achieve even greater increases in VE_C.