PVDF PTC Overcurrent Protection for Voltage Endurance
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Solution Overview
Problem
Existing over-current protection devices for high temperature applications face challenges in achieving low electrical resistivity and excellent voltage endurance capability, often requiring complex formulation designs with additional additives that compromise compatibility and stability.
Innovation Solution
An over-current protection device utilizing polyvinylidene difluoride (PVDF) as a matrix with specific proportions of α-PVDF, β-PVDF, and γ-PVDF crystalline phases, combined with a metal-ceramic compound conductive filler, eliminates the need for additional additives by enhancing voltage endurance and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional additives are added to improve voltage endurance capability, then voltage endurance capability is improved, but formulation design becomes complicated
Solution Approach 1:
The patent removes additional additives from the formulation by extracting only the essential components: PVDF polymer matrix with controlled crystalline phases and conductive filler. This simplifies the formulation while maintaining voltage endurance capability through the optimized PVDF crystalline structure rather than relying on multiple additives.
Solution Approach 2:
The patent changes the physical-chemical parameters of PVDF by controlling its crystalline phase composition (α-phase, β-phase, γ-phase ratios). This parameter adjustment improves voltage endurance capability inherently, eliminating the need for additional additives and simplifying the overall formulation design.
2Reliability
If conductive filler is added to reduce electrical resistivity, then electrical resistivity is reduced, but compatibility and formulation design become more complex
Solution Approach 1:
The patent achieves homogeneous distribution of conductive filler within the PVDF matrix by ensuring uniform dispersion. This homogeneous structure reduces electrical resistivity effectively while avoiding the need for complex compatibility agents or additional additives, thus simplifying the formulation.
3Temperature
If PVDF is used as matrix for high temperature application, then high temperature stability is improved, but voltage endurance capability needs further improvement
Solution Approach 1:
The patent changes the crystalline phase parameters of PVDF to optimize both high temperature stability and voltage endurance capability. By controlling the ratios of α-phase, β-phase, and γ-phase crystalline structures, the material achieves enhanced performance in both temperature resistance and voltage endurance without requiring additional additives.
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 low electrical resistivity and excellent voltage endurance, with the ability to recover from high temperature trips, maintaining stability and functionality without additional additives.
Implementation Method 1
the application mainly focuses on piezoelectricity or ferroelectricity of β-PVDF
Implementation Method 2
the application mainly focuses on piezoelectricity or ferroelectricity of β-PVDF
Implementation Method 3
the conductive filler is uniformly dispersed in the matrix and is used as an electrically conductive path
Implementation Method 4
the electrical resistance of the PTC conductive composite material remains extremely low at normal temperatures... when an over-current or an over-temperature situation occurs... the electrical resistance will instantaneously increase to a high electrical resistance state
Data Source
AI summary
An over-current protection device includes a first metal layer, a second metal layer and a heat-sensitive layer laminated therebetween. The heat-sensitive layer exhibits a positive temperature coefficient (PTC) characteristic and includes a first polymer and a conductive filler. The first polymer consists of polyvinylidene difluoride (PVDF), and PVDF exists in different phases such as α-PVDF, β-PVDF and γ-PVDF. The total amount of α-PVDF, β-PVDF and γ-PVDF is calculated as 100%, and the amount of α-PVDF accounts for 48% to 55%. The conductive filler has a metal-ceramic compound.