Embedded-Core Integrated Inductors With Tight PCB Windings
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Solution Overview
Problem
Current integrated circuit packaging technologies face challenges in achieving high performance, small form factor, and scalability for coupled inductors and transformers with embedded magnetic cores, particularly due to high costs associated with wafer-level integration and limitations in discrete inductor suitability for multiphase switching applications.
Innovation Solution
The method involves forming an integrated magnetic device using a prepreg or core mounted on a carrier, with plated and patterned winding layers, vias, and a solenoid-like approach with copper windings around a high-performance magnetic core, leveraging panel-level grinding and chemical mechanical planarizing to achieve tight windings and low via pitch, similar to wafer-level fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wafer level integration is used for coupled inductors, then performance and integration density are improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent divides the integrated magnetic device into multiple layers (first layer with first set of windings, second layer with second set of windings) separated by an insulating layer with via holes. This segmentation allows independent fabrication of each layer using standard PCB processes, avoiding the need for expensive wafer-level integration while achieving high integration density through vertical stacking of magnetic components.
Solution Approach 2:
The patent embeds magnetic cores within the multi-layer structure, placing first magnetic cores associated with first windings and second magnetic cores associated with second windings in nested configurations. This nesting approach enables compact integration of multiple magnetic components in a vertical arrangement, achieving high integration density without requiring costly wafer-level processing.
2Ease of manufacture
If discrete inductors are used for power supply applications, then manufacturing simplicity is maintained, but performance and form factor are insufficient for multiphase switching
Solution Approach 1:
The patent combines multiple discrete inductor functions into a single integrated magnetic device with coupled windings on a common substrate. Multiple sets of windings are arranged with magnetic cores to provide coupled inductance, enabling multiphase switching functionality while maintaining manufacturing simplicity through standard PCB fabrication processes rather than complex discrete assembly.
Solution Approach 2:
The integrated magnetic device serves multiple functions simultaneously: it provides coupled inductance for multiphase switching, offers magnetic shielding through embedded cores, enables tight winding configurations for high current density, and supports various via configurations for electrical connections. This multi-functionality replaces multiple discrete components while maintaining ease of manufacture.
3Ease of manufacture
If traditional PCB structures are used, then manufacturing cost is low, but magnetic flux leakage and parasitic effects increase
Solution Approach 1:
The patent embeds magnetic cores within the PCB structure, placing them in via holes or between layers to create closed magnetic flux paths. This nesting of magnetic cores within the traditional PCB architecture confines magnetic flux, reducing leakage and parasitic effects while maintaining compatibility with low-cost manufacturing processes.
Solution Approach 2:
The patent introduces magnetic cores as intermediary elements between windings to guide and confine magnetic flux. These cores act as mediators that redirect magnetic flux through defined paths, reducing leakage into surrounding areas and minimizing parasitic coupling, all while using materials and processes compatible with standard PCB fabrication.
4Manufacturing precision
If tight windings and low via pitch are achieved, then DC resistance decreases and performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent transitions from planar winding arrangements to three-dimensional multi-layer configurations, allowing windings to be distributed across multiple layers separated by insulating materials. This dimensional change enables tight effective winding pitch and low DC resistance by utilizing vertical space, while maintaining manufacturability through standard multi-layer PCB processes.
Solution Approach 2:
The patent segments the winding structure into multiple discrete layers, each with its own set of windings and magnetic cores. This segmentation allows independent optimization of each layer's winding density and via placement, achieving low DC resistance through tight effective spacing while simplifying manufacturing by treating each layer as a separate fabrication stage using standard PCB processes.
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 approach enables small form factor, high performance, and scalable integrated magnetic devices at a lower cost, with complete magnetic flux capture and reduced DC resistance, addressing the limitations of traditional technologies.
Implementation Method 1
The magnetic material is annealed in a magnetic field
Implementation Method 2
The magnetic material is annealed in a magnetic field
Implementation Method 3
solenoid-like approach with copper windings around a high-performance magnetic core
Implementation Method 4
complete magnetic flux capture
Implementation Method 5
leveraging panel-level grinding and chemical mechanical planarizing to achieve tight windings and low via pitch
Data Source
AI summary
In accordance with an embodiment of the application a method of forming an integrated magnetic device is described. A prepreg or core is mounted on a carrier. A winding layer is plated and patterned on the prepreg or core. Vias are plated. The silicon is placed on a die attach pad, ensuring sufficient clearance of die to vias and d/a char. The assembly is laminated and grinded to expose the vias. A 2nd layer of vias is provided by sputtering or plating followed by laminating assembly; and grinding assembly to expose vias. The windings are plated and patterned. A solder mask (SMSK) is applied and assembly finished.