Current Sensing Resistor Dual Metal Layer Design
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Solution Overview
Problem
Current sensing resistors require high resistance precision, typically in the milliohm range, and conventional Kelvin measurement methods struggle to minimize variations in manufacturing processes, especially when exposed metal between sensing and current pads affects resistance uniformity and stability.
Innovation Solution
A current sensing resistor design with a dual metal layer structure where sensing and current pads are separate and not extending beyond the metal layer area, accompanied by a protective layer and optional features like recesses and an auxiliary layer to minimize interference and enhance precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional Kelvin measurement method is used with exposed metal between pads, then manufacturing process is simpler, but resistance uniformity and stability deteriorate
Solution Approach 1:
The patent introduces a vertical layering dimension by placing the sensing pad and current pad on different metal layers (first metal layer and second metal layer respectively). This dimensional separation eliminates the interference of exposed metal between pads while maintaining manufacturing simplicity, as the layering structure naturally isolates the measurement path from the current path.
Solution Approach 2:
The patent segments the metal structure into distinct functional layers: a first metal layer for current conduction and a second metal layer for sensing. This segmentation separates the current-carrying function from the measurement function, eliminating the harmful interaction between exposed metal and measurement signals while keeping the manufacturing process straightforward.
2Device complexity
If exposed metal is present between sensing pad and current pad, then device structure is simpler, but measurement precision deteriorates
Solution Approach 1:
By transitioning from a planar layout to a vertical layered structure, the patent achieves both structural simplicity and measurement precision. The sensing pad and current pad are positioned on different vertical levels, eliminating the need for complex routing or shielding while ensuring accurate resistance measurement free from exposed metal interference.
Solution Approach 2:
The patent introduces an intermediary protective layer or insulating structure between the exposed metal and the measurement path. This intermediary element blocks the harmful electrical influence of exposed metal on the sensing pads while maintaining overall structural simplicity and not requiring complete redesign of the device architecture.
3Manufacturing precision
If repetitive measurement and adjustment is performed to achieve high precision, then resistance precision improves, but manufacturing time increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring the sensing and current pads on separate metal layers during the manufacturing process. This preliminary structural arrangement ensures that resistance measurements are inherently accurate from the first measurement, eliminating the need for repetitive measurement and adjustment cycles, thereby maintaining high precision while improving manufacturing efficiency.
Solution Approach 2:
The layered structure design makes the device self-correcting by naturally preventing measurement errors through its geometry. The sensing pads on one layer and current pads on another layer automatically eliminate interference effects, so the manufacturing process does not require additional adjustment steps - the structure itself ensures measurement accuracy without human intervention for fine-tuning.
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 effectively eliminates the impact of exposed metal, reducing measurement errors and achieving high-precision resistance values with improved stability and yield, allowing for more precise current sensing.
Implementation Method 1
the voltage difference V between the points 11 and 12, where V=V11−V12, can be measured and used for calculating resistance of the resistor 15 based on Ohm's Law, i.e. V=IR
Implementation Method 2
Kelvin measurement, which is a four-point type of measurement, is adopted to measure resistance of a current sensing resistor
Data Source
AI summary
A resistor device includes a resistor plate having opposite first and second surfaces; a first metal layer including first and second portions which are disposed on the first surface of the resistor plate at opposite first and second sides, respectively; and a second metal layer including a first sensing pad, a second sensing pad, a first current pad and a second current pad, separate from one another, wherein the first sensing pad and the first current pad are disposed on the first portion of the first metal layer and the second sensing pad and the second current pad are disposed on the second portion of the first metal layer. A protective layer is preferably provided, overlying the resistor plate and the first metal layer uncovered by the second metal layer.