Research On Resistor Packaging Protective Film Oxygen Evolution Protection And Mechanism Of Corrosion In High Electric Field And Humid Environment

Precision metal film resistor with low temperature coefficient,wide working temperature range,high power dissipation per unit area and other advantages,widely used in medical electronics,aerospace,precision instruments and other fields.Especially in high temperature,high humidity and other harsh environment,metal film resistor with high performance in high temperature and humid environment is needed,so the research on reliability of the metal film resistor become more and more important.This subject was found in the humid experiment of resistor,the resistor coated with phenolic resin composite in deionized water,In the case of electricity,the gas evaluates from the edge of resistor cap,after a preliminary study judgment that the gas was hydrogen and oxygen(produced by the decomposition of water),and after a short time of electrify,packaging coating not corrode;with time extend,the packaging film begin to corrode.So under the electric field,how to decompose the water? What is the reason of corrosion? We will discuss these problems in this thesis.This subject adopts two kind of composite materials of PF/EP,quality ratio is 4:3 and 7:1,to do reliability experiments in deionized water and NaOH solution of pH=10.In deionized water,the applied voltage is 10 V,20V,30 V,125V and 250 V respectively;In NaOH solution,the applied voltage is 0~10V.Analysis the structure of the PF/EP composite using infrared spectrum,simulate the electric field by using Ansys,providing data support for the analysis of the mechanism of gas evolution.The study of hydrogen evolution mechanism show that in deionized water,H2 and OH-generate on the cathode,the H2 in the form of H2-OH-ads to move to the anode,and generate the O2 in the anode.In NaOH solution,the H2 and O2 evolve from the cathode and anode separately,and emerge from the surface.IR analysis showed that PF/EP composites containing a large number of active group phenoxy(for example),the group of p–? and ?–? containing localized electrons,can delocalize under the action of a strong electric field.When the water adsorbs on the surface of the resistor,electronic exchange between the water and the thin polymer film,H2 and OH-evolve on the cathode.When OH-move to the anode surface,generate O2 due to loss of electronic.When the anode surface has a lot of OH-and not being consumed oxygen evolution in time,it will react with the active group of Ar-O-C in PF/EP composites in the electric field,make its bond rupture,the film is corroded.Obviously,the oxygen evolution reaction with PF/EP film corrosion reaction is a kind of competition.This study provides a new way to improve the reliability of the resistor by eliminate the resource of the water in humid and heat environment,and a new understanding of the polymer degeneration mechanism in electric field.