Multilayer Copper Laminate for High-Breakdown Coil Insulation
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Solution Overview
Problem
Existing laminates are inadequate for high-power inductive transmitter coils used in wireless charging systems due to insufficient dielectric breakdown strength and vulnerability to defects like porosity and impurities, which lead to electrical discharges and failures.
Innovation Solution
A laminate with multiple thin polymer film layers of varying dielectric constants and thicknesses, bonded together to distribute electrical stress and enhance breakdown strength, using materials like aromatic polyimide and polyfluoroalkoxy with ceramic fillers for improved insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing laminates are used for inductive transmitter coils, then the device can be manufactured with conventional materials, but the dielectric breakdown strength is insufficient and the coil fails under high power levels
Solution Approach 1:
The laminate is divided into multiple thin polymer film layers (at least three) with varying dielectric constants and thicknesses. This segmentation distributes electrical stress across multiple interfaces and prevents concentration of electrical fields that would cause breakdown in single-layer structures.
Solution Approach 2:
The invention uses composite construction with at least three different polymer films having dissimilar dielectric constants bonded together between copper layers. This composite structure creates multiple dielectric barriers that collectively provide superior breakdown strength compared to any single polymer material.
2Reliability
If single-layer polymer films are used, then the manufacturing process is simple, but the laminate is vulnerable to porosity and impurities causing electrical discharge
Solution Approach 1:
By segmenting the dielectric structure into multiple thin layers, the invention reduces the probability of defects spanning the entire thickness. Each thin layer is less susceptible to containing critical porosity or impurities, and the multiple interfaces create additional barriers to electrical discharge paths.
Solution Approach 2:
The multilayer construction acts as a preemptive defense against electrical breakdown. The varying dielectric constants create zones of different electrical stress distribution, and the multiple layers provide redundant barriers that cushion against the harmful effects of any single layer's defects.
3Reliability
If uniform polymer layers are used, then the manufacturing process is straightforward, but the electrical stress is not optimally distributed leading to premature failure
Solution Approach 1:
Different polymer layers are selected with specific dielectric constants and thicknesses optimized for their local position in the stack. Layers with higher dielectric constants are positioned to handle specific stress concentrations, creating locally optimized electrical stress distribution throughout the laminate structure.
Solution Approach 2:
The invention varies key parameters (dielectric constant and thickness) across different polymer layers to optimize electrical performance. By changing these parameters locally rather than uniformly, the structure achieves superior electrical stress distribution and breakdown strength.
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 laminate achieves higher dielectric breakdown voltage and reliability, reducing the risk of electrical failures and enabling efficient operation of inductive coils at high power levels.
Implementation Method 1
adjacent ones of the at least three polymer layers have dissimilar dielectric constant, Dk, values
Implementation Method 2
adjacent ones of the first and second outer copper layers, and the at least three polymer layers, are bonded to each other
Data Source
AI summary
A laminate includes a first outer copper layer; a second outer copper layer; a multilayer construct having at least three polymer films disposed between the first and second outer copper layers. Adjacent ones of the at least three polymer layers have dissimilar dielectric constant, Dk, values, dissimilar thicknesses, or preferably both dissimilar Dk values and dissimilar thicknesses. Adjacent ones of the first and second outer copper layers, and the at least three polymer layers, are bonded to each other. Each polymer film of the at least three polymer films has a voltage breakdown strength equal to or greater than 200 kV/mm, or equal to or greater than 5 kV at a film thickness of 25 micrometers.