Common Mode Filter Dummy Lead Segmentation
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Solution Overview
Problem
Miniaturization of common mode filters has led to increased sensitivity to external stimuli, resulting in signal distortion due to high-frequency noise, and issues with connection breakage and resistance increase, compromising performance and reliability.
Innovation Solution
A multilayer or thin film common mode filter design featuring spiral coils with lead portions connected to external electrodes and dummy lead portions, which are connected in series through conductive vias to enhance contact area and electrical connectivity, preventing defects and maintaining performance and reliability even at reduced sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the common mode filter is decreased for miniaturization, then the device becomes more compact and suitable for mobile components, but the connection portion between the internal coil and external electrode becomes more susceptible to breakage and resistance increase
Solution Approach 1:
The connection path is segmented into multiple portions by introducing dummy lead portions between the lead portion and external electrodes. This segmentation distributes the mechanical stress and electrical load across multiple smaller connection segments, preventing any single connection point from bearing excessive stress that could cause breakage or resistance increase during miniaturization.
Solution Approach 2:
Dummy lead portions are introduced as intermediary elements between the lead portion and external electrodes. These dummy lead portions act as buffer zones that absorb mechanical stress and provide additional connection paths, thereby protecting the primary lead portion-external electrode connections from breakage and resistance increase when the device is miniaturized.
2Volume of moving object
If the size of the external electrode and internal coil is decreased for miniaturization, then the device becomes more compact, but signal distortion due to high frequency noise increases
Solution Approach 1:
The patent transitions from a planar two-dimensional layout to a three-dimensional stacked configuration with coil layers arranged in the thickness direction. This dimensional change allows the filter to maintain effective filtering performance against high frequency noise while achieving miniaturization in the planar dimensions, as the vertical stacking provides sufficient electrical length and filtering capability without increasing the device footprint.
3Device complexity
If the lead portion is connected directly to external electrodes without dummy lead portions, then the structure is simpler, but connection breakage and resistance increase occur after reliability tests
Solution Approach 1:
Dummy lead portions are预先 (in advance) positioned between the lead portion and external electrodes to provide cushioning protection. These dummy lead portions absorb mechanical stress and electrical shocks before they can reach the critical lead portion-external electrode connections, thereby preventing connection breakage and resistance increase that would otherwise occur during reliability testing and operation.
Data Source
AI summary
A multilayer common mode filter includes: a body including a coil part having a plurality of spiral coils, wherein the coil part has one lead portion connected to one of external electrodes disposed on the body and one or more dummy lead portions each connected to the other external electrodes, and the lead portion is connected to dummy lead portions of other coil layers stacked in a thickness direction in series. Therefore, even though the common mode filter is miniaturized, the common mode filter may secure predetermined levels or more of performance and reliability.