Planar Transformer IC Packages With Low-Reluctance Core Paths
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Solution Overview
Problem
Magnetic-coupling isolation barriers, commonly used in electronic systems, face manufacturing issues such as misalignment and surface irregularities of transformer core pieces, leading to efficiency losses due to local breaks in the magnetic core, which are problematic for integrated circuit (IC) packages.
Innovation Solution
A planar transformer structure is developed using soft ferromagnetic materials for the core layers and substrate portions, with conductive traces forming coils and through holes filled with soft ferromagnetic material to enhance magnetic coupling and reduce reluctance, allowing for galvanic isolation in IC packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional magnetic core pieces are used in transformers, then galvanic isolation can be achieved, but misalignment and surface irregularities cause local breaks in the magnetic core, increasing reluctance and reducing efficiency
Solution Approach 1:
The magnetic core is divided into two separate planar layers (first core layer on primary side, second core layer on secondary side) that are manufactured independently and then joined through the substrate, allowing each layer to be fabricated with standard PCB tolerances without requiring precise alignment of multiple core pieces
Solution Approach 2:
The substrate acts as an intermediary that positions and joins the first and second core layers at contact regions, providing mechanical support and electrical isolation while maintaining magnetic flux continuity through the planned aperture structure
2Reliability
If traditional magnetic core pieces are used in transformers, then galvanic isolation can be achieved, but local breaks in the magnetic core cause loss in efficiency
Solution Approach 1:
Apertures are pre-formed in the substrate at strategic locations before the core layers are assembled, ensuring that magnetic flux paths are maintained through the contact regions and preventing local breaks that would cause energy loss
Solution Approach 2:
The transformer structure combines planar conductive traces, ferromagnetic core layers, and insulating substrate materials into a composite planar structure that maintains magnetic flux continuity while providing galvanic isolation
3Reliability
If traditional transformers with magnetic cores are used, then galvanic isolation is provided, but manufacturing complexities increase and scalability is reduced
Solution Approach 1:
The transformer structure is merged with the PCB substrate, eliminating the need for separate magnetic core assemblies and allowing the transformer to be manufactured as an integrated component using standard PCB fabrication processes
Solution Approach 2:
The planar transformer structure serves multiple functions: providing galvanic isolation, enabling magnetic coupling, and integrating directly with PCB manufacturing processes, making it universally applicable to various IC package designs
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
The planar transformer structure improves efficiency and scalability by reducing manufacturing complexities and enabling smaller, cost-effective IC packages with effective voltage isolation, facilitating the integration of high-voltage circuits like gate drivers in solid-state switches.
Implementation Method 1
A first core layer may be disposed over the first substrate portion (first surface). The first core layer may include a soft ferromagnetic material. A second core layer may be disposed over the second substrate portion (second surface). The second core layer may include a soft ferromagnetic material.
Implementation Method 2
Magnetic coupling typically relies on use of a transformer to magnetically couple circuits on the different sides of the transformer, typically referred to as the primary and secondary sides, while also providing galvanic separation of the circuits.
Data Source
AI summary
Aspects of the present disclosure include systems, structures, circuits, and methods providing planar transformers and planar transformer structures. The planar transformers and transformer structures can include first and second core layers of soft ferromagnetic material on opposite sides of an electrical substrate. First and second coils can be configured as conductive traces disposed on the opposite sides of the substrate. The first and second soft ferromagnetic layers are in contact in a contact region. One or more holes are disposed in either or both of the soft ferromagnetic layers and contain soft ferromagnetic material to reduce reluctance of the transformer structure. The planar transformer can be included in integrated circuit (chip) packages or modules. The packages and modules may include various types of circuits; in some examples, chip packages or modules may include a gate driver or other high voltage circuit.