Views:2 Author:Site Editor Publish Time: 2018-03-03 Origin:Site
(1) the surface of the lead is oxidized or coated too thinly to weld properly;
(2) poor spot welding between lead wire and aluminum foil, which did not eliminate the aluminum oxide film layer in the spot welding place of aluminum foil surface;
(3) the probability of low level failure is increased because the number of solder joints of single lead structure is few;
(4) although the contact area of the flat part at the root of the coarse lead is larger, the stress of the solder joint is also larger after spot welding, which may damage the contact site and worsen the contact condition during heat treatment or warm track.
(5) moisture enters the capacitor core and oxidizes the solder joint, which increases the contact resistance.
The specific factors causing the low-level failure of mica capacitors are summarized as follows:
(1) there is a thin film of Terran between the silver electrode and the lead copper foil and between the copper foil and the lead card. Under the low level condition, the applied voltage is not enough to break down the insulating film, and the gap capacitance is produced, and the contact resistance is increased.
(2) the silver electrode and copper foil are corroded by harmful gas, which increases the contact resistance. Silver and copper are easily vulcanized in a humid sulfur environment, which increases the contact resistance between the electrode and the lead.