Chip Resistor Sulfur Corrosion Protection via Overlay Geometry
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Solution Overview
Problem
Conventional chip resistors are prone to corrosion from airborne sulfur, sulfides, and sulfur-containing compounds, leading to increased resistance values and potential open-circuiting due to electrochemical reactions with silver or copper electrodes, especially in harsh environments.
Innovation Solution
The chip resistor design incorporates a substrate with first and second electrodes, a resistive layer, protection layers with overlay sides and planes, and coating layers to extend the distance between electrodes and the outside, forming a convex structure that prevents sulfur-containing compounds from reacting with the electrodes, using materials like nickel, palladium, and tin for the coating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver-containing materials are used as conductor materials to achieve good electrical connection, then electrical conductivity is improved, but susceptibility to sulfur corrosion increases
Solution Approach 1:
The patent introduces a protection layer comprising nickel and palladium as intermediary materials between the silver-containing conductor and the external environment. This protection layer acts as a mediator that prevents direct contact between sulfur-containing compounds and the silver electrodes, thereby maintaining electrical conductivity while providing corrosion resistance. The nickel-palladium alloy forms a barrier that blocks the electrochemical reaction between sulfur and silver.
Solution Approach 2:
The patent employs a composite material structure consisting of multiple layers with different functions: a silver-containing conductor layer for electrical conductivity, a nickel-palladium protection layer for corrosion resistance, and a glass overcoat for environmental protection. This composite structure combines materials with complementary properties to simultaneously achieve good electrical connection and sulfur corrosion resistance.
2Ease of manufacture
If conventional protection structures are used, then manufacturing simplicity is maintained, but sulfur-containing compounds can still react with electrodes
Solution Approach 1:
The patent uses a thin film protection layer made of nickel-palladium alloy deposited on the conductor surfaces. This thin film provides effective corrosion protection while maintaining the compact structure and not significantly increasing device volume. The glass overcoat also forms a protective shell that seals the internal components from the external environment, preventing sulfur-containing compounds from reaching the electrodes.
Solution Approach 2:
The nickel-palladium protection layer serves as an intermediary barrier between the silver electrodes and the corrosive environment. This intermediate layer is applied through established manufacturing techniques such as electroplating or sputtering, which are compatible with conventional chip resistor fabrication processes, thus maintaining ease of manufacture while providing effective corrosion protection.
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 corrosion from sulfur and sulfur-containing compounds, maintaining the resistance value and extending the lifespan of the chip resistor by creating a barrier that inhibits the diffusion of harmful substances, while being compatible with mass production and reducing manufacturing costs.
Implementation Method 1
The at least one coating layer covers the at least two overlay sides, the at least one overlay plane, and part of the two first electrodes and the two second electrodes
Data Source
AI summary
The disclosure provides a chip resistor including: a substrate, two first electrodes, two second electrodes, a resistive layer, at least one protection layer and at least one coating layer. The protection layer covers part of the two first electrodes, and includes at least two overlay sides and at least one overlay plane. The coating layer covers the at least two overlay sides, the at least one overlay plane, and part of the two first electrodes and the two second electrodes. The chip resistor uses the two overlay sides and the overplay plane to extend a distance between the two first electrodes and the outside. Therefore, it is difficult for the airborne sulfur, sulfides and sulfur-containing compounds to enter and react with the two first electrodes. Thus, the chip resistor can resist corrosion of harmful substances such as sulfur, sulfides and sulfur-containing compounds or halogens on the electrodes.