Film Capacitor Segmented Electrode Crack Prevention
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Solution Overview
Problem
The manufacturing process of film capacitors often results in cracking of the fuse pattern due to peeling charge discharge during the deposition of metal electrodes, which can lead to dielectric breakdown and permanent short-circuits.
Innovation Solution
The film capacitor design incorporates a second deposition electrode with widthwise slit portions and a second fuse pattern that can be fused by a current smaller than the first fuse pattern, reducing the risk of cracking by allowing controlled discharge of peeling charge and preventing permanent short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the film is peeled off from the cooling roll after metal deposition, then the deposition electrode is formed on the film, but peeling charge is generated in the film causing current flow through the fuse pattern which may cause cracking
Solution Approach 1:
The deposition electrode is segmented into multiple independent electrode sections by forming insulating margin portions at predetermined intervals in the longitudinal direction. This segmentation isolates charge accumulation in each section, preventing large-scale current flow through the fuse pattern during peeling discharge, thereby suppressing cracking while maintaining deposition quality
Solution Approach 2:
A fuse pattern with controlled low melting point characteristics is introduced as an intermediary element between the segmented electrodes. This fuse pattern can be selectively fused by peeling charge current to provide a safe discharge path, protecting the main electrode structure from damage while allowing controlled charge release
2Reliability
If a fuse pattern is formed on the deposition electrode to prevent permanent short-circuit, then dielectric breakdown protection is improved, but the fuse pattern is susceptible to cracking from peeling charge discharge
Solution Approach 1:
By segmenting the deposition electrode into multiple independent sections with insulating margin portions, the current path during peeling discharge is divided into multiple smaller paths. Each fuse segment handles only local charge discharge, reducing the current magnitude and preventing cracking that would occur with a single continuous fuse pattern
Solution Approach 2:
The fuse pattern parameters (width, thickness, material composition) are optimized to have a melting point and current-carrying capacity specifically tailored to handle peeling charge discharge. This allows the fuse to safely conduct discharge currents without cracking, while still providing protection against dielectric breakdown under normal operating conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses the occurrence of cracking in the fuse portion, ensuring self-preservation against dielectric breakdown and maintaining the integrity of the film capacitor during manufacturing and operation.
Implementation Method 1
the vacuum deposition apparatus feeds a film fed from an unwinding device to a cooling roll and deposits a metal on the film cooled upon contacting the cooling roll
Implementation Method 2
the cooling roll and the film are charged to positive and negative polarities to make the cooling roll easily come into tight contact with the film
Implementation Method 3
When, however, the film is peeled off from the cooling roll, peeling charge is generated in the film
Implementation Method 4
a deposition electrode is deposited and formed on a film by using, for example, a vacuum deposition apparatus. The vacuum deposition apparatus sprays a metal serving as a deposition electrode from a deposition device
Data Source
AI summary
A film capacitor according to the present disclosure includes a first film and a second film wound in a stacked state and a first deposition electrode and a second deposition electrode that are formed by metal deposition. The second deposition electrode includes widthwise slit portions, the widthwise slit portions crossing the second deposition electrode in its widthwise direction, split electrodes split by the widthwise slit portions, and a longitudinal slit portion extending in a longitudinal direction of the second deposition electrode in an ineffective electrode region shifted from an effective electrode region in the widthwise direction of the second deposition electrode. Each split electrode includes a first fuse portion bridging over a longitudinal slit portion and a second fuse portion that bridges over a widthwise slit portion and can be fused with a current smaller than a current for the first fuse portion.