Cr-Si-N Chip Resistor Composition for High Resistance and Low TCR
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Solution Overview
Problem
Existing chip resistors face challenges in achieving both high specific resistance and low Temperature Coefficient of Resistance (TCR), with existing technologies often prioritizing one at the expense of the other.
Innovation Solution
A chip resistor design incorporating an insulating substrate with a resistance element composed of Cr, Si, and N, and an electrode made of refractory metals, with specific atomic ratios and atom percentages to balance high specific resistance and low TCR, along with a production method involving sputtering and heat treatment to stabilize electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the resistance element uses conventional materials with high specific resistance (4000 μΩ·cm or higher), then the specific resistance is improved, but the TCR becomes poor (±300 to 500 ppm/K or lower)
Solution Approach 1:
The resistance element uses a composite material system comprising Cr-Si-N alloy with specific atomic ratios (Si/Cr: 0.5-2.0, N: 10-50 atom%). This composite structure enables simultaneous achievement of high specific resistance (2000-10000 μΩ·cm) and low TCR (±50 to ±200 ppm/K) by combining the beneficial properties of different elements in controlled proportions
Solution Approach 2:
The invention changes the compositional parameters of the resistance element by precisely controlling the atomic ratios of Cr, Si, and N. By adjusting the Si/Cr atomic ratio to 0.5-2.0 and N content to 10-50 atom%, the material properties are optimized to achieve both high specific resistance and low TCR, resolving the traditional trade-off between these parameters
2Reliability
If heat treatment is performed to stabilize electrical connections, then the electrical connection stability is improved, but surface oxynitride layer formation increases, reducing environmental resistance
Solution Approach 1:
The invention applies preliminary protective action by forming a gas barrier layer between the resistance element and the electrode before heat treatment. This pre-formed barrier prevents excessive oxynitride layer formation during subsequent heat treatment processes, maintaining both electrical connection stability and environmental resistance
Solution Approach 2:
A gas barrier layer acts as an intermediary between the resistance element and the electrode, preventing direct interaction that would lead to oxynitride formation. This intermediary layer allows heat treatment to proceed for electrical stabilization while blocking the harmful oxidation/nitridation reactions at the interface
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 achieves both high specific resistance and low TCR, while maintaining stable electrical connections through reduced surface oxynitride layer formation, enhancing environmental resistance and gas barrier properties.
Implementation Method 1
The electrode forming step includes forming the electrode on the resistance element by sputtering
Data Source
AI summary
A chip resistor includes an insulating substrate, a resistance element, and an electrode. The resistance element includes Cr, Si, and N and is disposed on the insulating substrate. The electrode includes at least one refractory metal and is disposed on the resistance element. An atomic ratio of Si to Cr in the resistance element is greater than or equal to ⅔ and less than or equal to 4 at least at a center of the resistance element in a thickness direction defined with respect to the resistance element. An atom percentage of N in the resistance element is lower than or equal to 50 atom % at least at the center of the resistance element in the thickness direction.