Encapsulated PCB High-Tension Pad Edge Extension
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Solution Overview
Problem
Encapsulated printed circuit boards (PCBs) in high-voltage or medium-voltage power distribution networks face a risk of electrical discharges between high-tension pads and shielding layers due to voids formed by thermal expansion differences between materials, which can lead to damage and failure.
Innovation Solution
The high-tension pad is extended to the peripheral edge of the PCB, preventing elongated voids from forming parallel to electrical field lines, thereby reducing the likelihood of discharges. This geometry ensures that field lines do not extend along the surface of the PCB, minimizing the risk of electrical discharges between the high-tension pad and the shielding layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the encapsulation body is made smaller, then space and weight are reduced, but the shielding layer gets closer to the high-tension pad, increasing the risk of electrical discharges
Solution Approach 1:
The high-tension pad is designed with non-uniform geometry, extending to the peripheral edge in specific regions where electrical stress is highest. This local extension creates larger clearance distances in critical areas while maintaining compact overall size, preventing discharges where they are most likely to occur without unnecessarily increasing the entire encapsulation body volume
Solution Approach 2:
The high-tension pad extends not only in the planar direction but also in the thickness direction of the PCB, creating a three-dimensional configuration. This multi-dimensional extension increases the effective clearance distance between the high-tension pad and the shielding layer without proportionally increasing the encapsulation body volume, as the extension utilizes the available thickness dimension
2Reliability
If the high-tension pad is extended to the peripheral edge, then the likelihood of discharges is reduced, but the PCB layout becomes more constrained
Solution Approach 1:
The high-tension pad is segmented into multiple regions with different extension characteristics. In regions where peripheral edge extension is most effective for discharge prevention, the pad extends to the edge. In other regions, the pad maintains conventional dimensions. This segmentation allows optimization of discharge resistance in critical areas without unnecessarily constraining the entire PCB layout
Solution Approach 2:
Instead of constraining the high-tension pad within a conventional rectangular boundary and adding separate protective structures, the invention inverts the approach by allowing the pad itself to extend to the peripheral edge. This inversion simplifies the overall structure by using the pad geometry itself as the primary discharge prevention mechanism, rather than adding separate complex protective elements
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 configuration significantly reduces the occurrence of electrical discharges, allowing for a more robust PCB assembly that can maintain voltage integrity even under thermal cycling, enabling a smaller encapsulation body and reduced space and weight while maintaining adequate voltage robustness.
Implementation Method 1
These different materials expand at different rates when heated, so that voids may form between the PCB body and the encapsulation body
Data Source
AI summary
Encapsulated PCB assembly (1) for electrical connection to a high- or medium-voltage power conductor in a power distribution network of a national grid, comprising a) a PCB (10), delimited by a peripheral edge (20) and comprising a high-tension pad (60, 62) on a voltage of at least one kilovolt, b) an electrically insulating encapsulation body (70) in surface contact with, and enveloping, the high-tension pad and at least a portion of the PCB edge adjacent to the high-tension pad, c) a shielding layer (80) on an external surface (90) of the encapsulation body and for being held on electrical ground or on a low voltage to shield at least a low-voltage portion of the PCB. The high-tension pad extends to the peripheral edge of the PCB.