# Flicker

Flicker noise is a form of electronic noise that was first described experimentally by John Bertrand Johnson (1925) and by Walter Schottky (1926) through theoretical analysis of measurement results. The effect was observed at the time with the emission of electrons from hot cathodes and explained by "sparkles" (English: flicker ) on the surface of the cathode. This term is first used in Schottky's publication. Therefore, in the English-language literature, flicker noise is also called flicker noise , which led to the Germanized term flicker noise.

Schottky uses Johnson's measurements to determine two different spectral noise power densities for different cathode materials, namely one spectrum that is proportional and the other one that is proportional . ${\ displaystyle 1 / f ^ {2}}$${\ displaystyle 1 / \ left ({f_ {0} ^ {2} + f ^ {2}} \ right)}$

It is no different from another noise phenomenon which is referred to in the literature as 1 / f noise .

The flicker noise is highly component-dependent and is a derivation from the 1 / f noise. Its formation is mainly observed in the metal connections of integrated circuits. It occurs more frequently at higher current densities in closely spaced metallic connections ( wire bonding ). Its influence is particularly noticeable at very low frequencies and is negligible from a frequency range greater than 10 kHz. ${\ displaystyle 1 / f}$

The measurement of the flicker noise can be used as a measure of the quality of the bond in integrated circuits and hybrids . It is a relatively quick and accurate method to non-destructively assess the reliability of the metal connections.

## Individual evidence

1. a b Alicja Konczakowska, Bogdan M. Wilamowski: Noise in Semiconductor Devices. In: Bogdan M. Wilamowski, J. David Irwin (Eds.): The Industrial Electronics Handbook. Volume 1: Bogdan M. Wilamowski, J. David Irwin: Fundamentals of Industrial Electronics. 2nd edition. CRC Press, Boca Raton FL et al. 2011, ISBN 978-1-4398-0279-3 , pp. 11-1-11-12: Chapter 11.