Coil Assembly Termination for Wireless Charging
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Solution Overview
Problem
Existing methods for electrically terminating coils to circuit boards in wireless charging systems often result in increased contact resistance and board thickness due to by-products, reducing wireless power transmission efficiency.
Innovation Solution
A coil assembly featuring a multilayer film with cut edges and a magnetic layer, electrically connected to a conductive terminal, and a continuous wire with alternating magnetic and metal layers, which minimizes contact resistance and thickness increase during termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding method is used to terminate the coil to the circuit board, then electrical connection is achieved, but the coil and circuit board may be penetrated causing damage
Solution Approach 1:
The coil structure is divided into multiple segments including a coil body portion and separate first/second extension portions that extend in opposite directions. This segmentation allows the extension portions to be selectively connected to the circuit board while the main coil body remains intact, preventing penetration damage while ensuring reliable electrical connection.
Solution Approach 2:
Different portions of the coil are designed with different properties: the coil body portion maintains its original structure for magnetic field generation, while the extension portions are specifically designed for connection to the circuit board. This local differentiation allows welding to be applied only where necessary without affecting the entire coil structure.
2Reliability
If related-art welding methods (laser, ultrasonic, resistance) are used to terminate the coil to the circuit board, then electrical connection is achieved, but the thickness of the circuit board increases due to by-products
Solution Approach 1:
The extension portions of the coil are extracted as separate connection elements that can be selectively welded to the circuit board. By removing only the necessary portions for connection rather than welding the entire coil, the amount of by-products generated is minimized, thus reducing thickness increase while maintaining reliable electrical connection.
3Reliability
If welding is used to electrically terminate the coil to the circuit board, then electrical connection is achieved, but contact resistance increases due to damage and by-products
Solution Approach 1:
The coil is segmented into a coil body portion and extension portions, where only the extension portions are subjected to welding. This minimizes thermal damage and by-products at the connection interface, reducing contact resistance while maintaining reliable electrical connection for power transmission.
Data Source
AI summary
The present disclosure relates to a coil assembly. According to a first embodiment of the present disclosure, there is provided a coil assembly including a coil including a multilayer film which is extended between a first longitudinal end and a second longitudinal end of the multilayer film, which are opposite to each other, and which is wound to form a plurality of loops which are substantially concentric, wherein the multilayer film includes: cut edges which are extended between the first longitudinal end and the second longitudinal end, and are opposite to each other and are substantially parallel to each other; a metal layer; and a magnetic layer disposed on the metal layer, wherein, at one or more of the first longitudinal end and the second longitudinal end of the multilayer film, the metal layer is electrically connected to a conductive terminal.