Semiconductor Current Rail with Grooves for Sensor Sensitivity
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Solution Overview
Problem
Conventional semiconductor packages face challenges in sensitivity and reliability due to manufacturing defects and alignment issues, particularly in current sensors where the magnetic field measurement is affected by the distance between the sensor and the current rail, and large currents flowing through the rail can cause electro-migration and mechanical stress, leading to accuracy and longevity issues.
Innovation Solution
A semiconductor package design featuring a current rail with grooves and a magnetic field generating portion, where the grooves are strategically placed to prevent solder flow and reduce mechanical stress, and an anti-solder layer is applied to prevent solder shorts, ensuring accurate current measurement and enhanced reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor is brought close to the current rail to improve sensitivity, then the sensitivity to magnetic field is improved, but the package becomes susceptible to manufacturing defects and alignment issues
Solution Approach 1:
The current rail is segmented into multiple sections with varying thicknesses, creating distinct functional zones: a thicker section for mechanical stability and soldering, and a thinner section for enhanced magnetic field generation. This segmentation allows the sensor to be positioned optimally for sensitivity while the thicker portions maintain reliability by reducing susceptibility to manufacturing defects.
Solution Approach 2:
Different sections of the current rail are designed with different thicknesses to perform different functions. The thinner section provides higher magnetic field intensity for sensor sensitivity, while the thicker sections provide mechanical robustness and soldering stability. This local quality variation resolves the contradiction by optimizing each region for its specific purpose.
2Measurement precision
If the current rail thickness is reduced to enhance magnetic field generation, then the magnetic field intensity is improved, but the mechanical strength and reliability are reduced
Solution Approach 1:
The current rail is divided into sections with different thicknesses, allowing the thinner section to generate stronger magnetic fields while the thicker sections maintain mechanical strength. This segmentation enables both high magnetic field intensity and structural robustness to coexist in different parts of the same component.
Solution Approach 2:
The current rail features non-uniform thickness with thinner regions optimized for magnetic field generation and thicker regions optimized for mechanical strength. This local quality variation allows the rail to simultaneously achieve high magnetic field intensity where needed and maintain overall structural integrity.
3Reliability
If grooves are added to prevent solder flow and reduce mechanical stress, then the reliability is improved, but the device complexity increases
Solution Approach 1:
Grooves are introduced into the current rail structure to segment the solder flow path and create mechanical stress relief zones. These grooves prevent solder from shorting between adjacent pads while also reducing thermal and mechanical stress concentrations, thereby improving reliability despite the increased structural complexity.
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
The design enhances the sensitivity and reliability of current sensors by maintaining accurate magnetic field measurement and reducing the impact of solder flow and mechanical stress, thereby improving the longevity and accuracy of the semiconductor package.
Implementation Method 1
a magnetic field generating portion. Along a current flow direction, the first groove is disposed between the first contact area and the magnetic field generating portion
Implementation Method 2
Hall-sensors sense the magnetic field of the current and provide a voltage (Hall voltage) proportional to the intensity of the current
Data Source
AI summary
In accordance with an embodiment of the present invention, a semiconductor package includes a current rail comprising a first contact area and a second contact area, a first groove and a second groove, and a magnetic field generating portion. Along a current flow direction, the first groove is disposed between the first contact area and the magnetic field generating portion and the second groove is disposed between the magnetic field generating portion and the second contact area. The thickness of the current rail at the first groove is smaller than the thickness of the current rail at the first contact area.