Coil Lead-Out Structure for Short-Circuit Safe Mounting
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Solution Overview
Problem
Existing coil devices face issues with reduced size leading to short circuits between lead-out portions and winding portions, and difficulty in ensuring mounting strength due to small flattened portions with limited solder fillet formation.
Innovation Solution
The coil device design includes a lead-out portion with a proximal portion continuing to the winding portion, a flattened portion inside the core, and a terminal portion outside the core, where the flattened portion extends diagonally from the proximal portion to the side surface, ensuring a larger area for solder fillet formation and reducing the risk of short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the coil device size is reduced, then the device becomes more compact, but the distance between the flattened portion and the winding portion decreases causing short circuit risk
Solution Approach 1:
The flattened portion is configured to extend in the radial direction of the winding portion, utilizing the radial dimension to increase separation distance. By extending the flattened portion radially outward from the winding portion, the design creates sufficient clearance in the radial direction while maintaining compact overall device dimensions, effectively preventing short circuits between the flattened portion and winding portion.
2Strength
If the flattened portion area is increased, then solder fillet formation is improved, but the device size increases
Solution Approach 1:
The flattened portion is strategically configured with increased area specifically at the region where solder fillet formation occurs, while maintaining compact dimensions in other areas. The flattened portion extends radially to provide sufficient surface area for reliable solder attachment, ensuring strong mounting strength without unnecessarily increasing the overall device volume.
3Ease of operation
If the flattened portion is positioned at the side surface of the core, then connection to mounting substrate is enabled, but the area available for solder fillet formation is limited
Solution Approach 1:
The flattened portion extends not only along the side surface but also radially outward from the winding portion, utilizing the radial dimension to create additional area for solder fillet formation. This radial extension provides sufficient surface area for reliable solder attachment while maintaining the side surface positioning necessary for mounting substrate connection.
Data Source
AI summary
A coil device includes a core containing a magnetic material and having a mounting surface and a side surface extending in a direction perpendicular to the mounting surface, and a wire including a winding portion disposed inside the core and a lead-out portion drawn out from the winding portion. The lead-out portion includes a proximal portion continuing to the winding portion and a flattened portion continuing to the proximal portion and being squeezed flat. The flattened portion includes an embedded portion disposed inside the core and a terminal portion having a plating layer and being disposed outside the core. The embedded portion extends diagonally from the proximal portion to the side surface. The terminal portion is exposed from the core at a central portion of the side surface in the direction perpendicular to the mounting surface. The terminal portion extends from the central portion to the mounting surface.