Surface-Mount Inductor Production via Preformed Tablet Encapsulation
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Solution Overview
Problem
Conventional methods for producing small-sized surface-mount inductors face challenges such as large material loss, increased cost, and reliability issues due to the springback phenomenon, making it difficult to achieve adequate contact between external electrodes and coil ends, especially when using thin wires.
Innovation Solution
A method involving a mold die assembly where a coil is encapsulated with a resin and filler, with preformed tablets having flat and pillar-shaped portions, allowing the coil ends to be fixed and embedded, and forming external electrodes for secure electrical connection, eliminating the need for clamping between mold dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistance welding is used to join coil ends to lead frame, then electrical connection is achieved, but the joined portion is likely to separate due to springback phenomenon
Solution Approach 1:
The patent removes the lead frame from the structure entirely, extracting the problematic joint between coil and lead frame. Instead, the coil ends are directly embedded in the encapsulation material, eliminating the springback separation issue that occurred with resistance welding to lead frame.
Solution Approach 2:
The patent merges the functions of electrical connection and mechanical support into a single integrated structure. The encapsulation material serves both as insulation/protective coating and as the structural element that holds the coil ends in position, eliminating the need for separate lead frame and joint operations.
2Strength
If lead frame is used for coil mounting, then structural support is provided, but large material loss occurs increasing cost
Solution Approach 1:
The patent extracts and removes the lead frame component entirely from the inductor structure. The encapsulation material replaces the lead frame's structural support function, eliminating the material loss associated with lead frame fabrication and disposal.
Solution Approach 2:
The patent uses composite encapsulation material (resin with magnetic powder filler) that provides both structural support and magnetic properties. This composite material replaces the traditional lead frame, providing necessary mechanical support while reducing material cost and waste.
3Stability of the object's composition
If terminal clamping portions are used to fix coil ends, then coil fixation is achieved, but mold die dimensions must be changed for different wire diameters
Solution Approach 1:
The patent segments the encapsulation material into distinct functional zones: a recessed portion for receiving the coil body and flat surfaces for receiving the coil ends. This segmentation allows each zone to perform its specific function without requiring adjustable mold components.
Solution Approach 2:
The encapsulation material's recessed portion and flat surfaces serve multiple functions simultaneously: they provide mechanical support, electrical insulation, and precise positioning for coil ends. This multi-functionality eliminates the need for specialized terminal clamping portions that would require dimension changes for different wire diameters.
4Stability of the object's composition
If coil ends are bent downward and placed in mold die assembly, then encapsulation is achieved, but displacement or deformation of coil occurs during material charging
Solution Approach 1:
The patent performs preliminary action by pre-forming the encapsulation material with recessed portions and flat surfaces before the encapsulation process. These pre-formed features are designed to receive and hold the coil in the correct position, preventing displacement or deformation during the charging of encapsulation material.
Solution Approach 2:
The recessed portion and flat surfaces of the encapsulation material act as intermediaries between the coil and the mold die assembly. These features provide a stable interface that holds the coil ends in position during encapsulation, preventing direct contact between the coil and mold walls that could cause deformation.
Data Source
AI summary
A method of producing a surface-mount inductor by encapsulating a coil with an encapsulation material containing a resin and a filler using a mold die assembly is provided. In the method, a tablet and a coil are used. The tablet is prepared by preforming the encapsulation material into a shape having a flat plate-shaped portion and a pillar-shaped convex portion on a peripheral thereof. The coil is a wound conductive wire having a cross-section of rectangular-shape. The coil is placed on the tablet to allow both ends of the coil to extend along an outer side surface of the pillar-shaped convex portion of the tablet. The coil and the encapsulation material are integrated together while clamping the both ends of the coil between an inner wall surface of the mold die assembly and the outer side surface of the pillar-shaped convex portion of the tablet, to form a molded body. External electrodes are formed on a surface of or around an outer periphery of the molded body in such a manner that the external electrodes are electrically connected to the both ends of the coil at least a portion of which is exposed to the surface of the molded body.