High-square-resistance safety film having horizontal spacing bars for isolation

Abstract

The invention relates to an electrode structure of a high-resistance metallized safety film isolated by transverse gap strips for capacitors. A composite film is formed by plating a zinc / aluminum metal electrode coating on a polypropylene dielectric base film, and the blank of the composite film is left Between the side and the thickened side of the plating layer, a plurality of transverse gap strips parallel to each other and equally spaced provide segmental protection for the contact connection between the thickened side and the gold-sprayed side. The thickness of the electrodes between adjacent transverse gap strips is reduced very thin, and then distributed in a trapezoidal shape to reduce the damage to the base film during the evaporation process, increase the working field strength of the medium; and make the energy required for self-healing Doubling down to ensure the goal of safe self-healing.

Description

technical field [0001] The invention relates to a metallized thin film material for capacitors, in particular to an improvement of a metallized safety film electrode structure for capacitors. Background technique [0002] A major shortcoming in the existing metallized film technology is that the dielectric base film is damaged during the process of evaporating electrodes and receiving high temperature and high-speed molecular precipitation of metal vapor, which makes the working field strength (or withstand voltage) of the medium Greatly reduced. Another major defect is that the connection between the thickened side of the metallized film and the gold spray is a weak link, which limits the impact current resistance and working life. And there is still no fundamental solution to these problems. [0003] In addition, the use of metallized safety film technology to improve the effectiveness of electroweak point breakdown self-healing in capacitors is well known. The metalliz...

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Problems solved by technology

It also has disadvantages: First, when breakdown and self-healing occur, although the capacitance of the isolated small electrode unit is very small, the area is about 50mm 2 , but with a normal breakdown self-healing point area of ​​0.5mm 2 In comparison, the difference is hundreds of times. Therefore, in the self-healing test of the film capacitor, the capacity loss value is many times larger than the standard index value of the ordinary metallized film capacitor, and cannot pass the test standard.

Second, when there is a voltage breakdown on the small electrode unit block, although there are externally connected narrow strips of coating to protect against fusing, many externally connected narrow strips of coating that have not been fused under normal operation are operated by the charging and discharging of the capacitor. When the current gathers and flows, the current density is much higher than that of the surrounding electrodes, which makes the narrow strip of the coating become a heating point. Due to the heating, the dielectric withstand voltage will inevitably be reduced, thereby reducing the dielectric working field strength of the capacitor.

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