Copper Overcurrent Interruption Structure for Solder Joint Reliability

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Solution Overview

Problem

The reliability of semiconductor devices is compromised due to differential deformation of metals in the protection mechanism and circuit pattern during temperature cycles, leading to deterioration at solder joint portions.

Innovation Solution

The overcurrent interruption mechanism is constructed using the same material as the circuit pattern, ensuring synchronized deformation and preventing deterioration at joined portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If different materials (nickel or aluminum) are used for the protection mechanism and copper for the circuit pattern, then the protection mechanism can effectively interrupt overcurrent, but the different metals deform differently in temperature cycles causing deterioration of solder joint portions

Engineering Contradiction:

Improveovercurrent protection functionVSAvoidsolder joint integrity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies homogeneity by using the same material (copper) for both the circuit pattern and the overcurrent interruption mechanism. This ensures identical thermal expansion and deformation characteristics during temperature cycles, preventing differential stress and solder joint deterioration while maintaining the overcurrent protection function.

Inventive Principle:

Principle #33Homogeneity

2Stability of the object's composition

If the same material (copper) is used for both the circuit pattern and overcurrent interruption mechanism, then deformation consistency is achieved and solder joint deterioration is prevented, but the design flexibility for selecting optimal protection mechanism materials is reduced

Engineering Contradiction:

Improvesolder joint integrityVSAvoidmaterial selection flexibility

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent resolves this contradiction by mandating homogeneity - the overcurrent interruption mechanism must be made of the same material as the circuit pattern. This eliminates material selection flexibility but ensures solder joint integrity through identical deformation characteristics during temperature cycling.

Inventive Principle:

Principle #33Homogeneity

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 approach enhances the reliability of the semiconductor device by maintaining consistent deformation and reducing temperature-related stress on solder joints, thereby improving long-term performance and preventing breakage.

Implementation Method 1

when an overcurrent flows, the overcurrent interruption mechanism melts and is cut

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

both components deform in a similar manner in a temperature cycle upon driving of devices

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS12588571B2Semiconductor device

Publication Date: 2026.03.24 MITSUBISHI ELECTRIC CORP

AI summary

A semiconductor device includes: an insulating substrate including a circuit pattern; a semiconductor chip mounted on the insulating substrate and connected to the circuit pattern; and an overcurrent interruption mechanism constituted with a same material as material of the circuit pattern, connected to the circuit pattern in series, wherein when an overcurrent flows, the overcurrent interruption mechanism melts and is cut.