Metallization Concavity Solder Stop for Shunt and Thermistor Joints

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Solution Overview

Problem

Solder creepage onto metal structures in electronic devices, such as shunts and thermistors, can lead to measurement inaccuracies and electrical shorting.

Innovation Solution

The implementation of a solder stop feature, which includes forming concavities in the sidewalls of the metallization adjacent to solder joints, preventing solder wetting with targeted regions of the metal structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solder joints are formed to attach metal structures to metallization, then electrical connections are established, but solder creepage onto metal structures causes measurement inaccuracies and electrical shorting

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidmeasurement accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The metal structure is divided into two distinct sections: a first section that contacts the metallization and forms the solder joint, and a second section that is spaced apart from the metallization and serves as the measurement region. This segmentation prevents solder creepage from reaching the measurement section while maintaining reliable electrical connection at the contact section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the metal structure are given different spatial relationships to the metallization. The first section is positioned to contact the metallization for solder attachment, while the second section is positioned away from the metallization to prevent solder contamination. This local differentiation of spatial quality ensures both connection reliability and measurement precision.

Inventive Principle:

Principle #3Local quality

2Reliability

If solder joints are formed to attach metal structures to metallization, then electrical connections are established, but solder creepage causes electrical shorting between circuit nodes

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidelectrical shorting

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The metal structure is divided into a first section for solder attachment and a second section spaced apart from the metallization. This segmentation creates a physical barrier that prevents solder from creeping onto the second section and causing electrical shorts between adjacent circuit nodes, while maintaining reliable electrical connection at the first section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first section of the metal structure acts as an intermediary element that accepts the solder joint attachment to the metallization, thereby protecting the second section (which contains measurement regions or other sensitive areas) from direct exposure to solder. This intermediary positioning prevents harmful solder creepage from reaching critical areas.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Volume of moving object

If metal structures are positioned close to metallization for compact design, then device size is reduced, but solder creepage risk increases

Engineering Contradiction:

Improvedevice sizeVSAvoidsolder creepage

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The metal structure is segmented into a first section that contacts the metallization and a second section that is spaced apart. This segmentation allows the overall structure to maintain a compact footprint while creating an internal spatial differentiation that prevents solder creepage from affecting the second section, even when the device is densely packed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design utilizes vertical spacing (distance from the first main surface of the metallization) to create protection against solder creepage. By positioning the second section at a specific vertical distance from the metallization surface, the design prevents solder from reaching sensitive areas while maintaining horizontal compactness for small device footprint.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12300643B2Solder stop feature for electronic devices

Publication Date: 2025.05.13 INFINEON TECHNOLOGIES AG

AI summary

Described are solder stop features for electronic devices. An electronic device may include an electrically insulative substrate, a metallization on the electrically insulative substrate, a metal structure attached to a first main surface of the metallization via a solder joint, and a concavity formed in a sidewall of the metallization. The concavity is adjacent at least part of the solder joint and forms a solder stop. A first section of the metal structure is spaced apart from both the metallization and solder joint in a vertical direction that is perpendicular to the first main surface of the metallization. A linear dimension of the concavity in a horizontal direction that is coplanar with the metallization is at least twice the distance by which the first section of the metal structure is spaced apart from the first main surface of the metallization in the vertical direction. Additional solder stop embodiments are described.