Embedded Transformer Resin Isolation for Reduced Winding Spacing
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Solution Overview
Problem
Existing embedded magnetic component devices face challenges in achieving high isolation performance due to limitations in dielectric strength, which necessitates large spacing between primary and secondary windings, impacting device miniaturization and safety certifications.
Innovation Solution
The use of ferrite magnetic cores with insulating substrates and resin-based isolation barriers, which create an air gap around the core and form solid bonded joints to reduce the isolation distance between windings, enhancing electrical insulation and allowing for smaller device designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epoxy gel is used to fill the cavity around the magnetic core, then the magnetic core is fully covered and fixed, but air bubbles form in the epoxy gel during solidification which can expand during reflow soldering and cause device failure
Solution Approach 1:
The patent removes the epoxy gel filling step entirely from the manufacturing process. Instead of filling the cavity with epoxy gel and risking air bubble formation, the design accepts an air gap between the magnetic core and cavity walls. This eliminates the source of the harmful air bubbles while still providing structural support through the cavity configuration.
Solution Approach 2:
The patent introduces a resin layer as an intermediary material between the magnetic core and the cavity walls. This resin layer fills the air gap in a controlled manner without introducing air bubbles, providing both structural support and electrical insulation while avoiding the harmful effects of trapped air bubbles that occur with epoxy gel filling.
2Reliability
If large spacing is maintained between primary and secondary windings to achieve high isolation performance, then electrical insulation is improved, but device size increases and miniaturization becomes difficult
Solution Approach 1:
The patent employs composite insulation structures combining multiple materials with different properties. The resin layer providing localized high-dielectric-strength insulation between windings is combined with the overall PCB substrate structure. This composite approach allows reduced spacing between windings while maintaining high isolation performance, enabling device miniaturization without sacrificing electrical safety.
Solution Approach 2:
The patent applies enhanced insulation specifically where needed - the resin layer is positioned strategically between the primary and secondary windings to provide localized high-dielectric-strength insulation. This allows the windings to be placed closer together overall while maintaining adequate isolation performance, thus reducing device size without compromising safety.
3Ease of manufacture
If the cavity is made slightly larger than the magnetic core to facilitate insertion, then assembly is simplified, but an air gap exists around the magnetic core which may affect isolation performance
Solution Approach 1:
The resin layer serves as an intermediary material that fills the necessary air gap between the magnetic core and cavity walls. This allows the cavity to remain slightly larger than the magnetic core for easy insertion, while the resin layer provides the electrical insulation needed to maintain isolation performance, effectively bridging the gap between mechanical assembly requirements and electrical performance requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces the isolation distance between primary and secondary windings to 0.4 mm, meeting safety standards while enabling more compact and efficient power supply device designs.
Implementation Method 1
an air gap between the cavity and the magnetic core
Implementation Method 2
including a solid bonded joint with the first side of the insulating substrate
Data Source
AI summary
An embedded magnetic component device includes a magnetic core located in a cavity extending into an insulating substrate. The cavity and magnetic core are covered with a cover layer. Through holes extend through the cover layer and the insulating substrate, and are plated to define conductive vias. Metallic traces are provided at exterior surfaces of the cover layer and the insulating substrate to define upper and lower winding layers. The metallic traces and conductive vias define the respective primary and secondary side windings for an embedded transformer. At least a first isolation barrier is provided on the cover layer, and at least a third insulating layer is provided on the substrate. The second and third insulating layers provide additional insulation for the device, and define and function as a circuit board for surface mounted power electronics.