PCB Isolation Barrier Case Layout for Compact Power Converters

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Solution Overview

Problem

The miniaturization of cases with power converters is hindered by the need for large component-free regions to maintain required clearance and creepage distances between primary and secondary circuits, as per UL standards.

Innovation Solution

A case design incorporating a header with a first isolation barrier and a cover with a second isolation barrier, where the barriers are adjacent to each other and match the shape of a slot in the PCB, allowing for reduced length while maintaining proper clearance and creepage distances, enabling miniaturization without compromising safety standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large component-free regions are maintained to ensure clearance and creepage distances, then safety standards are met, but case size increases and miniaturization is hindered

Engineering Contradiction:

Improvesafety distanceVSAvoidcase length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The case is divided into two separate sections: a header portion containing the first isolation barrier and a cover portion containing the second isolation barrier. This segmentation allows each barrier to independently contribute to the clearance and creepage distances, enabling the total safety distance to be achieved through distributed barriers rather than requiring a single large component-free region, thus reducing the overall case length

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The isolation barriers extend in the vertical dimension (from the PCB upward into the header and cover), rather than only in the horizontal plane. By utilizing the vertical space above the PCB, the design achieves the required clearance and creepage distances without proportionally increasing the horizontal case footprint, enabling miniaturization

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If isolation barriers are added to maintain safety distances, then clearance and creepage requirements are met, but device complexity increases

Engineering Contradiction:

Improveisolation distanceVSAvoidcase structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The first isolation barrier in the header and the second isolation barrier in the cover are designed to be adjacent to each other, effectively merging their isolation functions. This combined approach achieves the required total isolation distance while using simple, integrated structures rather than complex multi-component systems, reducing device complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The isolation barriers serve multiple functions simultaneously: they provide electrical isolation for clearance and creepage compliance, act as structural support elements for the header and cover, and define the boundaries for component placement. This multi-functionality reduces the need for additional separate components, simplifying the overall device structure

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11792919B2Case with isolation barriers

Publication Date: 2023.10.17 MURATA MFG CO LTD

AI summary

A case includes a header with a first isolation barrier, a cover with a second isolation barrier, and a printed circuit board (PCB) including a slot in which the first isolation barrier or the second isolation barrier is located and a primary-circuit side and a secondary-circuit side located on opposites sides of the slot.