Miniaturized PTC Over-Current Protection Device with Fluoropolymer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional over-current protection devices face challenges in miniaturization, as reducing their size leads to decreased voltage endurance and inferior resistance recovery, making them prone to blowout and unsuitable for high-temperature applications.
Innovation Solution
Incorporating carbon black and a fluoropolymer with a melting point higher than 150°C in the PTC material layer, with specific volume percentages, to create a miniaturized over-current protection device that exhibits excellent voltage endurance and superior resistance jump, while maintaining high endurable power per unit area and low power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the over-current protection device is reduced, then the device can be miniaturized for size-reduced electronic products, but the voltage endurance decreases and the device cannot withstand large currents and high power
Solution Approach 1:
The patent uses a composite PTC material layer comprising fluoropolymer matrix with carbon black filler (30-34% by volume) and flame retardant (2-10% by volume). This composite structure enables the miniaturized device to maintain high voltage endurance and reliability despite reduced size, as the carbon black provides conductive pathways while the fluoropolymer matrix ensures thermal stability above 150°C
Solution Approach 2:
The patent optimizes the volume percentage parameters of each component: fluoropolymer (65-70%), carbon black (30-34%), and flame retardant (2-10%). By precisely controlling these parameters, the device achieves both miniaturization and maintained voltage endurance, resolving the contradiction between size reduction and reliability
2Volume of moving object
If the size of the over-current protection device is reduced, then the device can be miniaturized, but the resistance recovery becomes inferior and the resistance jump cannot be controlled within an appropriate range
Solution Approach 1:
The patent precisely controls the carbon black volume percentage at 30-34% and flame retardant at 2-10% to achieve optimal resistance jump control (0.80-1.20 at 16V/50A by 1000 cycles). This parameter optimization enables both miniaturization and superior resistance recovery performance
Solution Approach 2:
The patent enhances the local quality of the PTC material layer by strategically distributing carbon black fillers and flame retardants within the fluoropolymer matrix. This localized material optimization ensures controlled resistance jump characteristics in the miniaturized device structure
3Temperature
If a fluoropolymer with high melting point is used in the PTC material layer, then the device can withstand high temperature applications, but the manufacturing complexity increases
Solution Approach 1:
The patent creates a composite material system where fluoropolymer matrix (providing high-temperature resistance above 150°C) is combined with carbon black filler and flame retardant. This composite approach achieves high-temperature withstand capability while managing material complexity through functional integration
Solution Approach 2:
The patent applies flame retardant locally at 2-10% volume percentage within the PTC material layer to enhance high-temperature performance. This localized addition provides thermal stability without significantly increasing overall device complexity
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 device achieves a resistance jump within a controlled range, passes cycle life tests at 16V/50A and 25V/50A without blowout, and demonstrates high endurable current and power per unit area, making it suitable for size-reduced electronic products and high-temperature applications.
Implementation Method 1
Because the resistance of conductive composite materials having a positive temperature coefficient (PTC) characteristic is very sensitive to temperature variation, it can be used as the material for current sensing devices
Implementation Method 2
The polymer matrix comprises a fluoropolymer having a melting point higher than 150° C.
Implementation Method 3
The carbon black is dispersed in the polymer matrix, and comprises 30-34% by volume of the PTC material layer
Data Source
AI summary
An over-current protection device comprises first and second electrode layers and a PTC material layer laminated therebetween. The PTC material layer comprises a polymer matrix and carbon black. The polymer matrix comprises a fluoropolymer having a melting point higher than 150° C. The carbon black is dispersed in the polymer matrix. A resistance jump Rjump_1000@16V/50A of the over-current protection device at 16V/50 A by 1000 cycles is 0.80-1.20. A resistance jump Rjump_1000@25V/50A of the over-current protection device at 25V/50 A by 1000 cycles is 0.90-1.30.