Embedded Ferrite Inductors for Low-Profile Coreless Substrates
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Solution Overview
Problem
Current solutions for integrating inductors into electronic substrates, such as air core inductors and magnetic core inductors, face challenges in achieving high inductance density and low Z-height, especially in coreless substrates, while also avoiding issues like magnetic filler leaching in standard fabrication processes.
Innovation Solution
The use of high-permeability magnetic ferrite materials to form inductors within coreless electronic substrates, where the magnetic ferrite materials are processed to prevent leaching into plating and etching solutions, allowing for high inductance density and low-loss planar magnetic inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic resins are used to form inductors in coreless substrates, then inductance density is improved, but magnetic fillers leach into plating and etching solutions causing process instability
Solution Approach 1:
A barrier layer is introduced as an intermediary between the magnetic filler-containing layer and the plating/etching solutions. This barrier layer prevents direct contact and leaching of magnetic fillers into the chemistry, thereby maintaining process stability while allowing the magnetic inductor structure to function. The barrier layer acts as a mediator that isolates the harmful interaction between magnetic fillers and plating/etching chemistries.
Solution Approach 2:
The potential harm of magnetic filler leaching is converted into a benefit by using the leaching mechanism itself to form a protective barrier. The barrier layer is designed to be formed from or by the magnetic filler material, transforming the problematic leaching behavior into a useful protective function that prevents further leaching and maintains solution stability.
2Quantity of substance
If conventional magnetic core inductors are used, then inductance density is improved, but Z-height increases making them unsuitable for coreless substrates
Solution Approach 1:
The inductor structure is transitioned from a three-dimensional magnetic core architecture to a planar two-dimensional structure. By forming the magnetic inductor within the plane of the coreless substrate rather than extending vertically with a thick magnetic core, the design achieves high inductance density while maintaining low Z-height. This dimensional transformation allows the inductor to be integrated into thin-coreless substrate architectures.
Solution Approach 2:
Thin film magnetic materials are used to create the inductor structure instead of bulky magnetic cores. The magnetic inductor is formed as a thin planar structure within the substrate layers, enabling high inductance density to be achieved without increasing the vertical thickness. This thin-film approach allows integration into coreless substrates with strict height constraints.
3Ease of manufacture
If magnetic resins are formulated to suit standard fabrication processes, then process compatibility is improved, but magnetic properties deteriorate
Solution Approach 1:
The magnetic inductor structure is segmented into distinct functional layers: a magnetic filler-containing layer that provides magnetic properties, a barrier layer that prevents leaching, and conductive trace layers that form the inductor coils. This segmentation allows each layer to be optimized independently - the magnetic filler layer maintains high magnetic properties while the barrier layer ensures process compatibility, avoiding the need to compromise magnetic properties for processability.
Solution Approach 2:
A composite structure is created combining magnetic fillers embedded in a dielectric matrix with an additional barrier layer. This composite approach allows the magnetic resin to maintain its magnetic properties while the barrier layer provides the necessary process compatibility. The composite structure separates the conflicting requirements of magnetic performance and fabrication process compatibility into different material components.
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 the fabrication of coreless substrates with integrated inductors that have high inductance density and low-loss characteristics without increasing the Z-height, and can be integrated into existing manufacturing processes without altering the chemistry or equipment.
Implementation Method 1
inductors are passive electrical components that store energy in a magnetic field generated by magnetic materials within the inductors
Implementation Method 2
high-permeability magnetic ferrite materials to form inductors
Implementation Method 3
inductors are passive electrical components that store energy in a magnetic field generated by magnetic materials within the inductors
Data Source
AI summary
An inductor can be formed in a coreless electronic substrate from magnetic materials and/or fabrication processes that do not result in the magnetic materials leaching into plating and/or etching solutions/chemistries, and results in a unique inductor structure. This may be achieved by forming the inductors from magnetic ferrites. The formation of the electronic substrates may also include process sequences that prevent exposure of the magnetic ferrites to the plating and/or etching solutions/chemistries.