PTC Over-Current Protection Device with Integrated Nickel Foil
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Solution Overview
Problem
Existing over-current protection devices using PTC conductive composite materials face challenges in mass production and cost reduction due to the need for manual attachment of nickel plates during spot-welding, which is detrimental to the materials and limits their application in high voltage and high current environments.
Innovation Solution
An over-current protection device is designed with a resistive device, insulation layer, and electrode layer, allowing for surface-mount technology such as reflow or spot-welding, enabling easier integration with a Protective Circuit Module (PCM) or external electrodes, thereby facilitating mass production and reducing manufacturing time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nickel plate is attached to the PTC device to protect it during spot-welding, then the PTC device can withstand high voltage and high current, but the manual attachment process increases manufacturing complexity and reduces productivity
Solution Approach 1:
The patent combines the nickel plate protection function directly into the PTC device structure by laminating a nickel foil layer between the PTC material layer and the electrode foil. This integration eliminates the need for separate manual attachment of nickel plates, allowing the device to withstand spot-welding while enabling automated mass production.
Solution Approach 2:
The patent creates a composite structure consisting of multiple layers: PTC material layer, nickel foil layer, and electrode foil layer. This composite material approach provides both the protective function against spot-welding damage and the electrical conductivity needed for operation, while enabling automated manufacturing processes.
2Object-affected harmful factors
If a nickel plate is manually attached to the PTC device, then spot-welding can be performed without damage, but the manufacturing process becomes complex and costly
Solution Approach 1:
The protective nickel foil is merged with the PTC device structure through lamination, creating an integrated component that requires no separate attachment steps. This reduces manufacturing complexity while maintaining protection against spot-welding damage.
Solution Approach 2:
The nickel foil is pre-laminated to the PTC material layer before the final device assembly and spot-welding process. This preliminary preparation ensures protection is already in place, eliminating the need for complex manual attachment during manufacturing.
3Productivity
If traditional reflow methods are used to integrate the PTC device, then mass production is enabled, but the high temperature damages the PTC materials and affects recovery behavior
Solution Approach 1:
The patent changes the welding temperature parameter from traditional reflow temperatures (typically above 200°C) to a lower temperature range (below 150°C) that is sufficient for joining the device to the PCB but does not damage the PTC material's recovery properties. This enables mass production while preserving functional reliability.
Solution Approach 2:
The patent replaces the traditional reflow soldering process with a lower-temperature welding process that achieves the same mechanical and electrical connection function without the harmful thermal effects on the PTC material.
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 allows for efficient and cost-effective integration of the over-current protection device with PCM or external electrodes, ensuring reliable protection without damaging the PTC materials, and maintains the recovery behavior of the PTC resistive device by using spot-welding at a lower temperature than traditional reflow methods.
Implementation Method 1
the resistance of PTC conductive composite material remains extremely low at normal temperature, so that the circuit or cell can operate normally. However, when an over-current or an over-temperature event occurs in the circuit or cell, the resistance instantaneously increases to a high resistance state
Implementation Method 2
The conductive connecting member penetrates or goes through the electrode layer, the insulation layer and the first electrode foil to electrically connect the electrode layer and the first electrode foil
Data Source
AI summary
An over-current protection device includes a resistive device, an insulation layer, an electrode layer and at least one electrically conductive connecting member. The resistive device includes a first electrode foil, a second electrode foil and a positive temperature coefficient (PTC) material layer laminated between the electrode foils. The insulation layer is formed on the surface of the first electrode foil, and the electrode layer is formed on the surface of the insulation layer. The conductive connecting member penetrates the electrode layer, the insulation layer and the first electrode foil for electrically connecting the electrode layer and the first electrode foil. The conductive connecting member is insulated from the second electrode foil. One of the first and second electrode foils is configured to electrically connect to a protective circuit module (PCM), and the other one is configured to electrically connect to an electrode terminal of a battery to be protected.