Core-Shell Conductive Fillers for PTC Elements
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Solution Overview
Problem
Current Macromolecule Based Conductive Composite Materials face challenges in achieving low room-temperature resistivity, weather durability, and voltage resistance, particularly due to limitations in conductive filler properties such as carbon black's limited conductivity and metal powders' susceptibility to oxidation, which hinder miniaturization and processing of PTC components.
Innovation Solution
A Macromolecule Based Conductive Composite Material comprising a mixture of polyolefins, conductive filler with a core-shell particle structure, and a coupling agent, specifically titanate, is developed to enhance conductivity and dispersion, with the conductive filler consisting of core-shell particles of tantalum, zirconium, or titanium with boride, nitride, or silicide layers, and the coupling agent improving filler distribution and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal powder is used as conductive filler, then resistance is reduced, but the material is susceptible to oxidation causing resistance increase
Solution Approach 1:
The patent uses metal carbide, metal nitride, metal silicide, or metal boride ceramic powder as conductive filler instead of pure metal powder. These ceramic materials combine the high conductivity benefits of metals with oxidation resistance, forming a composite material that maintains stable resistance without requiring protective packaging.
Solution Approach 2:
The patent creates an oxidation-resistant environment by selecting inherently inert ceramic materials (metal carbides, nitrides, silicides, or borides) that do not react with oxygen. This eliminates the need for protective packaging while maintaining low resistance and stability.
2Object-affected harmful factors
If metal carbide, metal nitride, metal silicide or metal boride ceramic powder is used as conductive filler, then oxidation resistance is improved, but processing difficulty increases and distribution in polymer deteriorates
Solution Approach 1:
The patent optimizes the particle size parameters of the ceramic conductive filler to improve processability. By controlling particle size and distribution parameters, the material becomes easier to mix and process while maintaining its oxidation-resistant properties and electrical conductivity.
Solution Approach 2:
The patent ensures uniform local distribution of ceramic conductive filler particles throughout the polymer matrix. This localized even distribution improves both processing characteristics and electrical performance by creating consistent conductive pathways without aggregation.
3Reliability
If the proportion of metal carbide, metal nitride, metal silicide or metal boride ceramic powder is increased, then resistance is reduced, but processing difficulty increases
Solution Approach 1:
The patent optimizes the proportion and particle size parameters of ceramic conductive filler to achieve a balance between electrical conductivity and processability. By carefully controlling these parameters, the material achieves low resistance while remaining easy to process and manufacture.
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 solution achieves low room-temperature resistivity, outstanding weather durability, and good voltage resistance, enabling the production of PTC components with improved performance and miniaturization capabilities, including small-sized components like 1210, 1206, 0805, and 0603, with resistivity as low as 0.01 Ωm and excellent resistor repeatability.
Implementation Method 1
coupling agent accounts for 0.05% ̃5% of the volume of conductive filler... The mentioned coupling agent is titanate... (c) Coupling agent accounts for 0.05% ̃5% of the volume of conductive filler
Implementation Method 2
Regarding the Macromolecule Based Conductive Composite Material with conductive filler of mental power, it has a low resistance, but the mental powder is easy to oxidize... Regarding carbon black as conductive filler, because its' special structure of aggregates and the polar group on the surface can make a good adhesive properties
Implementation Method 3
Conductive filler with particles structure of core-shell type, which accounts for 25% ̃80% of volume fraction of the Macromolecule Based Conductive Composite Material... the volume resistivity is under 0.03 Ωm, but 0.02 Ωm is preferred, 0.01 Ωm is better
Data Source
AI summary
A macromolecule-based conductive composite material and a PTC element. The macromolecule-based conductive composite material comprises: a macromolecule base material, having a volume fraction of the macromolecule base material of 20%-75%; a conductive filler with a core-shell granule structure and dispersed in the macromolecule base material, having a volume fraction of 25%-80%; and a coupling agent, being a titanate coupling agent and accounting for 0%-5% of the volume of the conductive filler. The PTC element prepared by using the macromolecule-based conductive composite material comprises at least two metal electrode plates (12, 12′), a macromolecule-based conductive composite material (11) being closely combined with the metal electrode plates (12, 12′). The PTC element prepared from the macromolecule-based conductive composite material has the advantages of low room-temperature resistivity, outstanding weather durability, good voltage resistance and good resistor repeatability.