Isolation Transformer Package Gap Design for Magnetostriction
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Solution Overview
Problem
Magnetic-coupling isolation barriers in transformers used for galvanic isolation in solid state switches face manufacturing challenges due to the inclusion of a magnetic core, which complicates integrated circuit (IC) packages.
Innovation Solution
A transformer-based IC package design featuring a substrate with a cavity for a soft ferromagnetic magnetic core, a cap to seal the cavity, and conductive traces forming first and second coils, encapsulated by a molding material, which includes a gap to manage magnetostriction effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic core is included in the transformer for galvanic isolation, then magnetic coupling and flux channeling are achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the physical state and properties of the magnetic core by introducing a gap that allows the core to expand and contract. This parameter change enables the core to accommodate magnetostriction effects without transmitting stress to surrounding components, thereby maintaining reliable galvanic isolation while reducing manufacturing complexity through simplified stress management
Solution Approach 2:
The patent introduces an intermediary gap between the magnetic core and the cavity wall. This gap acts as a mediator that decouples the magnetic core from mechanical constraints, allowing the core to freely expand and contract during magnetostriction cycles without transferring stress to the substrate or encapsulant, thus simplifying the overall manufacturing process
2Reliability
If a magnetic core is included in the transformer for galvanic isolation, then magnetic coupling is achieved, but manufacturing cost increases
Solution Approach 1:
The patent modifies the dimensional parameters of the magnetic core by providing a gap that accommodates its expansion and contraction. This parameter change eliminates the need for expensive precision mounting structures and stress-compensation mechanisms, thereby reducing manufacturing cost while maintaining reliable galvanic isolation
Solution Approach 2:
The patent extracts the magnetic core from its traditional constrained mounting arrangement and places it in a cavity with a gap that allows free expansion. This extraction from mechanical constraints simplifies the manufacturing process and reduces costs by eliminating complex mounting structures while preserving the essential galvanic isolation function
3Stability of the object's composition
If the magnetic core is constrained by the substrate, then structural stability is improved, but magnetostriction effects cause stress and potential damage
Solution Approach 1:
The patent introduces a gap as an intermediary element between the magnetic core and the cavity wall. This gap serves as a buffer that absorbs the dimensional changes caused by magnetostriction, preventing stress transmission to the substrate and encapsulant while maintaining the structural stability of the overall package
Solution Approach 2:
The patent provides a gap beforehand that anticipates and accommodates the expansion and contraction of the magnetic core during operation. This preemptive cushioning space prevents stress buildup and potential damage from magnetostriction effects while maintaining structural integrity, eliminating the need for complex stress-management mechanisms
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 design enables efficient galvanic isolation with reduced manufacturing complexity and cost, allowing for smaller package sizes and higher scalability in IC packages.
Implementation Method 1
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
Implementation Method 2
a magnetic core disposed in the cavity, where the magnetic core includes a soft ferromagnetic material
Implementation Method 3
A transformer based integrated circuit (IC) package may include a substrate including a cavity, where the cavity includes an aperture; a magnetic core disposed in the cavity, where the magnetic core includes a soft ferromagnetic material, where the cavity is configured to provide a space between an interior surface of the cavity and an exterior surface of the magnetic core
Data Source
AI summary
Isolation transformer packages and structures and related methods reduce or minimize deleterious effects arising from magnetostriction during operation of the included transformer. An example transformer based integrated circuit package includes a substrate including a cavity, with the cavity including an aperture. A magnetic core is disposed in the cavity, with the magnetic core includes a soft ferromagnetic material. The cavity is configured to provide a space between an interior surface of the cavity and an exterior surface of the magnetic core. A cap is disposed in the aperture and configured to seal the aperture. A plurality of conductive traces forming first and second coils is disposed about the magnetic core, with the first and second coils and magnetic core forming a transformer.