Resistor Electrode Design for Current Detection
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Solution Overview
Problem
Miniaturization of electronic equipment leads to high current density at the mounted section of current detection resistors, causing electro-migration and potential connection failures due to increased current density, which affects current detection accuracy.
Innovation Solution
The resistor design incorporates a second electrode portion made of higher resistivity material than the first electrode portion and solder, distributing current density uniformly from the solder to the inside of the electrode, reducing concentration at the electrode ends and enhancing tolerance against electro-migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the resistor is miniaturized, then the size of the resistor is reduced, but the current density at the mounted section increases causing electro-migration
Solution Approach 1:
The electrode is designed with non-uniform cross-sectional area, where the cross-sectional area at the mounted section (near solder joint) is larger than at other sections. This local variation in geometry distributes the current density more evenly, preventing concentration at the mounted section while maintaining the overall miniaturized size of the resistor.
2Power
If copper is used as electrode material, then the electrical conductivity is high, but current concentration occurs at the edges of the electrode
Solution Approach 1:
The electrode geometry is designed with varying cross-sectional area along its length, creating local quality differences that naturally distribute current density. The larger cross-sectional area at the mounted section reduces current concentration, while the overall high-conductivity copper material maintains low electrical resistance.
3Reliability
If the electrode cross-sectional area is increased at the mounted section, then current density distribution is improved, but the overall size of the resistor increases
Solution Approach 1:
The electrode is conceptually segmented into different sections with different cross-sectional areas. The mounted section has a larger cross-sectional area optimized for current distribution, while other sections maintain smaller dimensions to keep the overall resistor size compact. This segmentation allows localized optimization without global size increase.
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 design effectively prevents connection failures and improves current detection accuracy by reducing current concentration at the electrode ends, thereby enhancing the resistor's tolerance against electro-migration.
Implementation Method 1
the second electrode portion consisting of material having higher resistivity than the first electrode portion and having higher resistivity than solder
Implementation Method 2
the voltage caused at both ends of the resistor by the current is detected, and the current is detected from already-known resistance value of the resistor
Data Source
AI summary
Provided is a resistor for current detection, wherein connection failure etc. due to electro-migration is prevented from being generated in state that the resistor is mounted on a mounting board. The resistor has a resistance body (11) and electrodes (12). The electrode (12) includes first electrode portion (12a) connected to the resistance body (11) and second electrode portion (12b) formed on the first electrode portion (12a). The second electrode portion (12b) consists of material having higher resistivity than the first electrode portion (12a) and solder, which is used for mounting the resistor on the mounting board.