Suspended Magnetic Subassembly for High Voltage Isolation
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Solution Overview
Problem
Existing integrated electronic devices face challenges in achieving high voltage isolation and efficient electromagnetic interference (EMI) performance due to asymmetrical lead frame designs, which lead to excessive voltage differentials and potential arcing, and increased vertical thickness complicates mold flow during manufacturing.
Innovation Solution
A packaged electronic device design featuring a symmetrically located magnetic assembly suspended on a conductive support structure, with a laminated magnetic assembly attached to the lead frame structure, providing increased spacing between high and low voltage domains and enhancing voltage withstanding performance without affecting mold material flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spacing between die attach pad and package leads is increased to reduce electric field intensity, then high voltage withstanding performance is improved, but the area available for integrated magnetics circuitry is reduced
Solution Approach 1:
The magnetic assembly is suspended in the vertical dimension above the die attach pad rather than being placed laterally adjacent to it. This vertical stacking approach allows increased lateral spacing between high voltage leads and die attach pad while maintaining compact package footprint, thereby improving high voltage withstanding performance without sacrificing integrated magnetics area.
2Object-affected harmful factors
If the vertical thickness of laminated magnetic components is increased to improve EMI performance, then electromagnetic interference shielding is improved, but mold flow problems occur during manufacturing
Solution Approach 1:
The magnetic component is divided into multiple thin laminated layers rather than using a single thick component. This segmentation reduces the vertical thickness of each individual layer, improving mold flow characteristics during packaging while maintaining effective EMI shielding through the stacked laminated structure.
3Device complexity
If an asymmetrical lead frame design is used to integrate passive components, then device integration is improved, but excessive voltage differentials cause external arcing during manufacturing testing
Solution Approach 1:
The lead frame is designed with asymmetrical placement of conductive features where the die attach pad and magnetic assembly support are positioned at different locations and orientations. This asymmetrical configuration, combined with increased spacing and vertical suspension, manages voltage differentials between high voltage primary leads and low voltage secondary circuitry, preventing external arcing during manufacturing testing while maintaining component integration.
Data Source
AI summary
A packaged electronic device includes a die pad directly connected to a first set of conductive leads of a leadframe structure, a semiconductor die attached to the conductive die pad, a conductive support structure directly connected to a second set of conductive leads, and spaced apart from all other conductive structures of the leadframe structure. A magnetic assembly is attached to the conductive support structure, and a molded package structure that encloses the conductive die pad, the conductive support structure, the semiconductor die, the magnetic assembly and portions of the conductive leads, the molded package structure including a top side, and an opposite bottom side, wherein the lamination structure is centered between the top and bottom sides.