Metal Plate Resistor with Embedded Electrodes for Low TCR
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Solution Overview
Problem
Existing metal plate resistors have high resistance values and temperature coefficient ratios (TCR) due to current flowing only through electrodes and surface portions, limiting the reduction of resistance values and increasing TCR as resistance decreases.
Innovation Solution
A metal plate resistor design featuring recesses at opposing ends with electrodes embedded within, where the electrodes have lower specific resistance than the resistive element, and a protection film between them, allowing current to flow uniformly and reducing resistance and TCR by increasing the contact area and current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current flows only through electrodes and surface portions of the resistive element, then the structure is simple, but the resistance value cannot be reduced and TCR increases
Solution Approach 1:
The invention transitions from surface-level current flow to three-dimensional current distribution by forming recesses that extend into the resistive element. This dimensional change allows current to flow through both the surface and internal regions, increasing the effective current path area and reducing both resistance value and TCR.
Solution Approach 2:
The recesses create a porous-like structure within the resistive element, providing multiple current flow paths through the material. This increases the effective cross-sectional area for current flow, thereby reducing resistance and improving TCR stability without compromising structural integrity.
2Reliability
If electrodes are made of copper with high conductivity, then connection is good, but TCR increases due to large TCR of copper
Solution Approach 1:
The invention applies different material properties to different regions: copper electrodes provide high conductivity and connectivity at the contact points, while the metal resistive element with recesses provides low TCR for the main resistance function. This local differentiation allows each component to optimize its specific function.
Solution Approach 2:
The resistor combines copper electrodes with a metal resistive element (such as nickel-chromium or nickel-copper alloys) to create a composite structure. This composite approach leverages the high conductivity of copper for connectivity while using the metal resistive element's stable TCR characteristics for precise resistance control.
3Manufacturing precision
If recesses are formed to increase current flow area, then resistance and TCR are reduced, but manufacturing complexity increases
Solution Approach 1:
The resistive element is segmented by forming recesses that divide the material into distinct regions. This segmentation increases the surface area and creates multiple current flow paths, effectively reducing resistance and TCR while maintaining a relatively simple overall structure that can be manufactured using standard processes.
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 reduces resistance values and TCR, stabilizes connectivity, enhances heat dissipation, and improves mounting strength, while maintaining accurate electrode formation and adhesiveness without heating, thus addressing the limitations of existing resistors.
Implementation Method 1
a current flows through only the plurality of electrodes and a portion of the front surface or the back surface of the resistive element
Implementation Method 2
The plurality of electrodes are formed by, for example, plating the resistive element with copper
Data Source
AI summary
In a metal plate resistor according to the present disclosure, each of a pair of electrodes includes a first portion and a second portion. The first portion protrudes from one surface of a resistive element to be in contact with an end of a protection film. The second portion is disposed in a corresponding recess of a pair of recesses. In a direction in which the pair of electrodes is arranged, the second portion has a length longer than a length of the first portion.