Multilayer PCB Fuse Element Array for Higher I²t and Breaking Capacity

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Solution Overview

Problem

Existing chip fuses face a challenge in balancing thermal energy handling (I^2t) and breaking capacity, with traditional designs often resulting in undesirable energy distribution that leads to package damage and re-arcing during overcurrent events.

Innovation Solution

The design incorporates a dual-fuse element array with thinner, narrower fuse elements arranged in a matrix across multiple substrate layers, distributing energy to the sides of the package instead of the top, enhancing I^2t and breaking capacities while maintaining package integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If traditional single-fuse element design is used, then package structure is simple, but I^2t handling capacity is insufficient and energy distribution causes package damage

Engineering Contradiction:
ImproveI^2t handling capacityVSAvoidfuse element structure
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The fuse element is divided into multiple segments arranged in series between the terminals. Each segment is separated by insulating layers, creating a segmented structure that distributes thermal energy along the length of the fuse element rather than concentrating it at a single point. This segmentation increases the I^2t handling capacity while managing energy distribution to prevent package damage.

Inventive Principle:
Principle #1Segmentation

2Strength

If thicker fuse elements are used, then breaking capacity is reduced, but I^2t handling capacity increases

Engineering Contradiction:
Improvebreaking capacityVSAvoidI^2t handling capacity
Core Design Contradiction:
StrengthVSUse of energy by moving object

Solution Approach 1:

The fuse element is divided into multiple thinner segments arranged in series rather than using a single thick element. This segmentation allows the fuse to maintain higher breaking capacity (thinner individual segments break more easily) while achieving higher I^2t handling capacity through the cumulative effect of multiple segments that distribute thermal energy along their length.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fuse element is configured to extend in the vertical dimension between terminals rather than being a single horizontal layer. This vertical arrangement allows thinner segments to achieve the required I^2t capacity through their extended path length, resolving the trade-off between thickness and I^2t handling.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If fuse element energy is distributed to top of package, then manufacturing is simple, but package damage and re-arcing occur

Engineering Contradiction:
Improveenergy distribution patternVSAvoidpackage damage
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The segmented fuse element structure naturally distributes energy along its vertical length between terminals, with each segment contributing to the overall energy distribution pattern. This segmentation prevents energy concentration at the top of the package, reducing package damage and re-arcing risks while maintaining manufacturability through standard layering processes.

Inventive Principle:
Principle #1Segmentation

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 achieves higher I^2t values and breaking capacities, minimizing package damage and ensuring faster opening of the fuse, thus preventing re-arcing and maintaining the package's integrity during short circuit events.

Implementation Method 1

Each fuse element consists of at least two fuse element portions disposed between terminals... when the chip fuse element ruptures, a larger proportion of energy is distributed along the sides of the component package rather than the top of the package

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4280251A1Arrayed element design for PCB fuse
Publication Date: 2023.11.22 LITTELFUSE INC
  • EP4280251A1 patent drawingFigure 1A~1C
  • EP4280251A1 patent drawingFigure 2A~2B
  • EP4280251A1 patent drawingFigure 3A~3C

AI summary

A chip fuse includes a first terminal disposed on a first end of a fuse element array and a second terminal disposed on a second end of the fuse element array opposite the first end. The fuse element array includes multiple layers disposed in a stacked arrangement, each layer including a first terminal portion disposed within the first terminal, a second terminal portion disposed within the second terminal, a first fuse element portion orthogonal to and extending between the first terminal portion and the second terminal portion, and a second fuse element portion orthogonal to and extending between the first terminal portion and the second terminal portion. The first fuse element portion is adjacent the second fuse element portion.