Back-Side Transformer IC Packages for Galvanic Voltage Isolation
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Solution Overview
Problem
Magnetic-coupling isolation barriers used in transformers for galvanic isolation in integrated circuits face manufacturing challenges, particularly for IC packages, due to the inclusion of a magnetic core.
Innovation Solution
A chip package design with a lead frame and semiconductor dies on one side, and a transformer configuration with a ferromagnetic core and coils on the opposite side, providing magnetic coupling and galvanic isolation while avoiding the manufacturing issues associated with magnetic cores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic core is used in transformers for galvanic isolation, then magnetic coupling and voltage isolation are achieved, but manufacturing problems and complexity arise in IC packages
Solution Approach 1:
The patent extracts the magnetic core from the traditional transformer structure and replaces it with a planar magnetic coupling structure formed directly on the substrate. This removes the problematic 3D magnetic core component while retaining the essential magnetic coupling function for galvanic isolation, thereby simplifying manufacturing.
Solution Approach 2:
The patent replaces the mechanical assembly of a separate magnetic core with windings with a integrated planar structure where magnetic coupling is achieved through patterned conductive traces on a substrate. This substitution of mechanical construction with a planar fabrication approach resolves manufacturing complexity.
2Reliability
If traditional transformer structures with magnetic cores are used, then galvanic isolation is provided, but device size and cost increase
Solution Approach 1:
The patent removes the bulky 3D magnetic core from the transformer structure and replaces it with a planar magnetic coupling structure that integrates directly into the IC package substrate. This extraction dramatically reduces the volume required for galvanic isolation while maintaining functionality.
Solution Approach 2:
The patent transitions from a 3D magnetic core structure to a 2D planar magnetic coupling structure on the substrate. This dimensional change enables galvanic isolation to be achieved with significantly reduced package volume, as the magnetic coupling is distributed across the plane rather than concentrated in a vertical core structure.
3Reliability
If magnetic cores are integrated into IC packages, then voltage isolation is achieved, but manufacturing precision and scalability are reduced
Solution Approach 1:
The patent replaces the mechanical integration of separate magnetic core components with a planar fabrication process where magnetic coupling structures are formed using standard semiconductor manufacturing techniques. This substitution enables better manufacturing precision and scalability by utilizing established fabrication processes.
Solution Approach 2:
The patent creates a universal planar substrate structure that can serve multiple functions: providing magnetic coupling for galvanic isolation, serving as a circuit board for signal routing, and enabling standardized manufacturing processes. This multi-functionality improves manufacturing precision and scalability by consolidating multiple functions into a single manufacturable structure.
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
Enables smaller, cost-effective, and scalable IC packages with improved voltage isolation, meeting safety standards for creepage and clearance requirements.
Implementation Method 1
The first and second coils can be disposed about the transformer core in a transformer configuration... configured to magnetically couple the first and second semiconductor dies
Implementation Method 2
A ferromagnetic core can be disposed in the package body adjacent a second side of the lead frame... a magnetic core to provide a magnetic path to channel flux created by the currents
Data Source
AI summary
Aspects of the present disclosure include systems, structures, circuits, and methods providing integrated circuit (chip) packages or modules having a transformer that is disposed or mounted on or to a side of the lead frame opposite to the related semiconductor dies of the chip package. The transformer may be placed on a PCB structure. In some examples, an insulating coating may be placed on the package to increase the isolation capability of the final package. The packages and modules may include various types of circuits; in some examples, chip packages or modules may include a galvanically isolated gate driver or other high voltage circuit.