Planar Transformer Stress-Dissipation Layout for Insulation Reliability
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Solution Overview
Problem
Planar transformers experience mechanical stress and non-uniform thickness of insulating layers due to coefficient of thermal expansion (CTE) differences between conductive and dielectric materials, leading to potential breakdowns and reduced electrical performance.
Innovation Solution
Incorporation of stress dissipation regions and support elements in the transformer design to manage mechanical stress and ensure uniform thickness of insulating layers, using curved shapes and support elements to distribute stress and maintain consistent insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymeric dielectric material layers are used to electrically decouple the coils, then galvanic insulation is achieved, but non-uniform thickness and mechanical stress lead to breakdowns and reduced reliability
Solution Approach 1:
The patent applies preliminary action by forming a planarization layer before depositing the insulating polymer material. This planarization layer pre-compensates for the non-uniform thickness that would otherwise develop during polymer deposition, ensuring uniform total thickness and preventing the dome-shaped profile that causes external turn breakdowns.
Solution Approach 2:
The patent introduces a planarization layer as an intermediary between the coil structure and the insulating polymer material. This intermediate layer acts as a stress-dissipating buffer that prevents mechanical stress from the CTE mismatch from concentrating at the coil-polymer interface, thereby preventing delamination and breakdowns.
2Ease of manufacture
If thermal cycling is used during manufacturing, then dielectric material hardening is achieved, but high CTE difference causes mechanical stress and breakdowns
Solution Approach 1:
The planarization layer serves as a mediator between the coil structure and the insulating polymer, absorbing and distributing the mechanical stress generated during thermal cycling. This intermediate layer prevents stress concentration at the coil-polymer interface, maintaining interface strength despite the CTE mismatch between materials.
Solution Approach 2:
The patent changes the physical and mechanical parameters of the interface region by introducing the planarization layer with different mechanical properties than either the coil or the polymer. This parameter change allows the structure to withstand thermal cycling stresses that would otherwise cause interface failure.
3Object-affected harmful factors
If insulating polymer material is used for galvanic insulation, then voltage protection is achieved, but thickness variation causes electric field concentration and discharge at external turns
Solution Approach 1:
The planarization layer is formed in advance to create a uniform surface before polymer deposition. This preliminary action ensures that the final insulating structure has uniform thickness, preventing the external turn breakdowns that occur when the upper coil follows a dome-shaped profile due to non-uniform polymer thickness.
Solution Approach 2:
The patent addresses the two-dimensional thickness variation problem by introducing a third element (the planarization layer) that modifies the underlying surface topology. This dimensional approach allows uniform polymer deposition by pre-flattening the surface, thereby eliminating electric field concentration at external turns.
4Strength
If materials with lower CTE difference are used, then mechanical stress is reduced, but design constraints increase and electrical performance decreases
Solution Approach 1:
Rather than changing the material selection (which would increase design constraints and reduce electrical performance), the patent introduces a planarization layer as an intermediary structure. This approach maintains the original material choices while still reducing mechanical stress at the interface, avoiding the trade-offs associated with material substitution.
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
Stabilizes the transformer by reducing mechanical stress and ensuring uniform insulation thickness, preventing breakdowns and maintaining electrical performance.
Implementation Method 1
a first insulating layer extending along a first path; a second insulating layer extending along a second path; a galvanic insulation layer extending between the first and the second insulating layers
Implementation Method 2
coils and layers of dielectric material have Coefficients of Thermal Expansion (CTE) that are significantly different from each other
Implementation Method 3
Incorporation of stress dissipation regions and support elements in the transformer design to manage mechanical stress
Data Source
AI summary
Galvanic insulation device includes an upper coil in a first insulating layer; a lower coil in a second insulating layer; a galvanic insulation region extending between the first and the second insulating layers; and a first conductive via. Each of the upper coil and the lower coil includes turns, a first electrical contact region and a second electrical contact region, electrically coupled to the turns. The first conductive via is coupled to a first structural portion of the lower coil (2b), coupled to the turns or to the first or second electrical contact region. The first structural portion includes a first stress dissipation region having a curved shape and misaligned to the upper coil.