PTC Over-Current Protection Device with Ceramic Carbide Fillers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive composite materials with positive temperature coefficient (PTC) characteristics used in over-current protection devices face challenges with high resistance during repetitive over-current or over-temperature events, leading to shortened battery life due to inadequate conductivity and trip jump behavior.
Innovation Solution
Incorporating conductive ceramic carbide filler and carbon black of specific sizes into the PTC material layer, which includes crystalline polymer, to achieve low resistance and superior trip jump behavior, with a volume resistivity between 0.07 and 0.32 Ω-cm and a resistance ratio R100/Ri between 3 and 20.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black is used as the conductive filler in PTC material, then the material can be manufactured, but the resistance is too high to meet low resistance requirements
Solution Approach 1:
The patent combines carbon black filler with ceramic carbide filler in a crystalline polymer matrix to create a composite PTC material. This composite structure leverages the low cost and processability of carbon black while incorporating ceramic carbide particles that provide enhanced conductivity, achieving a balance between manufacturability and electrical performance with volume resistivity between 0.07-0.32 Ω-cm
Solution Approach 2:
The patent optimizes the volume resistivity parameter of the PTC material by controlling the ratio and particle size distribution of carbon black to ceramic carbide fillers. By adjusting these parameters, the material achieves optimal conductivity for low-resistance applications while maintaining the PTC effect for over-current protection
2Ease of manufacture
If carbon black filler is used in PTC material, then the material can be processed, but the resistance remains too high for low resistance applications
Solution Approach 1:
The patent creates a composite filler system where ceramic carbide particles are distributed within the carbon black matrix in the crystalline polymer. This composite approach maintains the processability benefits of carbon black while introducing highly conductive ceramic carbide pathways that reduce overall resistance to meet low-resistance application requirements
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 results in an over-current protection device with significantly improved conductivity and trip jump behavior, maintaining low resistance and extending the lifetime of batteries by effectively managing over-current events.
Implementation Method 1
Because the resistance of conductive composite materials having a positive temperature coefficient (PTC) characteristic is very sensitive to temperature variation
Implementation Method 2
The conductive ceramic carbide filler and the conductive carbon black filler are dispersed in the crystalline polymer
Data Source
AI summary
An over-current protection device includes two metal foils and a PTC material layer laminated therebetween. The PTC material layer has a volume resistivity between 0.07 Ω-cm and 0.32 Ω-cm. The PTC material layer includes a crystalline polymer, a conductive ceramic carbide filler of a particle size between 0.1 μm and 50 μm and a volume resistivity less than 0.1 Ω-cm, and a carbon black filler. The weight ratio of the carbon black filler to the conductive ceramic carbide filler is between 1:90 and 1:4. The conductive ceramic carbide filler and the carbon black filler are dispersed in the crystalline polymer. The resistance ratio R100/Ri is between 3 and 20.