For PPP with p-n transitions consider that current through transition is the sum of direct and return currents, and them them drobovy noise is inherent in everyone. Therefore in transistors shot noise arise in emitter and collector transitions:
The main contradiction of modern equipment consists in that. That if special measures for increase of reliability are not taken and the equipment of management is more difficult and more exact, the less it is reliable. Special sharpness is gained by the requirement of safe work of REA in system of complex automation of management processes with use of difficult multicoherent systems. Refusal of similar systems can lead to catastrophic consequences.
drobovy noise. This noise arises owing to fluctuation of concentration of carriers of a charge due to accident of processes of generation and a recombination. Most often for its definition use Schottky's formula and mean square value of noise current is defined as
Many researchers who are engaged in reliability of REA in a number of the works, showed that own noise of PPP, electrovacuum devices, resistors, plug sockets, contacts of the relay and other REA elements bear information on their reliability.
uneven distribution of current in structure. Rather seldom short circuits result from casual hit in the PPP case of conducting particles. Short circuits of electrodes of structure with a crystal arise sometimes because of sagging of internal conductors owing to their excess length.
Gradual refusal is the refusal which resulted from gradual change of characteristics of a product. Refusal of the auxiliary elements which are not influencing reliability call minor malfunction. Minor malfunctions subdivide into defects and malfunctions. Malfunctions which at the time of their detection do not lead to damage or violation of work and adjustment of the device are called as defects, but can cause in the future the similar phenomena.
Resistors check on the level of the third harmonica. Thin-film condensers (TPK) check for dielectric breakdown, use the parameters characterizing reliability of an internal field in dielectric, consider density of the volume charge accumulated at the annex to TPK of constant tension near microledges i.e. in areas of localization of a field.
Irreversible transformation of PPP at the expense of a strong local warming up, the electric current proceeding through PPP. It is formed or the melted structures, or break of the internal connecting conductor, or formation of the carrying-out canal between different structures of PPP.
Many researchers noted that main types of refusals of PPP and the integrated schemes (IS) are predicted on the level of their LF of noise therefore it is considered that through characteristics of LF of noise it is possible to receive indicators of reliability of PPP and IS. As the predicting character it is possible to use any of the considered characteristics: Effective tension of noise, noise coefficient, spectral density of power, autocorrelation function.
The most frequent reason, according to many experts, the finished goods reducing quality the latent defects are and an important role in a problem of improvement of quality and reliability of products of electronic equipment (ITE) allocate for nondestructive tests (NRI) - defectology, science about the principles, methods and sensors of defects.
It is noted that function of autocorrelation and spectral density of power of any casual process are closely interconnected and for data acquisition about this process (where the most fully physical essence and parameters et000ogo process are reflected enough to measure one of these characteristics. But, from the point of view of convenience of measurements under production conditions preference. it is given to the spectral density of power of noise.
where tcpi - the average time of correct work between two next refusals of i-that sample of the equipment, M - number of the tested samples. It is understood as the average time of the repaired product between two next refusals;
Experiments of many researchers showed essential changes of the PPP parameters in the course of tests if big tension in a combination with high temperature of environment is attached to transitions of PPP. It was proved that at such tension in electric field there is a division and group of positive and negative ions into surfaces, drift of these ions towards the electrodes having the corresponding sign of a charge. It was proved that these processes are a source of LF of noise and are responsible for change of key parameters of PPP in time.