PTC Chip Hot Pressing Eliminates Welding Degradation
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Solution Overview
Problem
The high welding temperature required in conventional methods for making PTC circuit protection chip devices degrades the PTC body, leading to reduced electrical properties and shorter service life due to the melting of the polymer matrix and particulate conductive filler.
Innovation Solution
A method involving a spacer unit in a hot pressing process is used to bond the PTC polymer material with metal-plated copper foil electrodes, eliminating the need for high-temperature welding by forming a PTC laminate that is then cross-linked and cut into chip devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is used to attach terminal leads to electrodes, then electrical connection is achieved, but the high welding temperature degrades the PTC body and reduces service life
Solution Approach 1:
The patent replaces the thermal welding process with a mechanical cold-pressing process. Terminal leads are attached to electrodes through cold-pressing at room temperature or low temperature, eliminating the high-temperature thermal field that causes PTC body degradation. This mechanical substitution preserves the integrity of the PTC polymer material while achieving reliable electrical connection.
Solution Approach 2:
The patent changes the temperature parameter from high (welding temperature ≥260°C) to low (cold-pressing temperature ≈ room temperature or slightly elevated). This parameter change eliminates thermal degradation of the PTC body while maintaining the electrical connection function through mechanical pressure-induced bonding.
2Reliability
If high welding temperature is used to attach terminal leads, then electrical connection is achieved, but electrical properties of the PTC chip are degraded
Solution Approach 1:
The patent replaces thermal welding with mechanical cold-pressing to attach terminal leads. This substitution eliminates the high-temperature thermal field that disrupts the conductive filler network and degrades electrical properties, while still achieving reliable electrical connection through mechanical bonding.
3Ease of manufacture
If conventional welding process is used, then manufacturing is simplified, but PTC body degradation occurs due to high temperature
Solution Approach 1:
The patent replaces the welding process with a cold-pressing process. This substitution eliminates the need for complex welding equipment and high-temperature control systems, while simplifying the process by performing attachment at or near room temperature. The mechanical pressing process is easier to control and eliminates PTC body degradation.
Solution Approach 2:
The patent changes the temperature parameter from high (welding) to low (cold-pressing), which simplifies the manufacturing process by eliminating the need for high-temperature equipment and complex thermal management. The low-temperature mechanical pressing process is more easily controlled and integrated into the overall manufacturing flow.
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
This approach maintains the electrical properties of the PTC chip devices, enhancing their service life and performance by avoiding the degradation caused by high welding temperatures.
Implementation Method 1
when the temperature of the polymer matrix is raised to its melting point, crystals in the crystalline region start melting, which results in generation of a new non-crystalline region
Implementation Method 2
The PTC effect is a phenomena that when the temperature of the polymer matrix is raised to its melting point, crystals in the crystalline region start melting
Implementation Method 3
subjecting the stack to a hot pressing process, so that the first and second electrode sheets contact and are pressed against the PTC polymer material and the spacer unit and so that the PTC polymer material is bonded to and cooperates with the first and second electrode sheets
Data Source
AI summary
A method of making a PTC protection chip device includes: preparing an assembly of a PTC polymer material, a spacer unit, and first and second electrode sheets of a metal-plated copper foil, the PTC polymer material and the spacer unit of the assembly being sandwiched between and cooperating with the first and second electrode sheets to form a stack; subjecting the stack to a hot pressing process, so that the first and second electrode sheets contact and are pressed against the PTC polymer material and the spacer unit and so that the PTC polymer material is bonded to and cooperates with the first and second electrode sheets to form a PTC laminate; and cutting the PTC laminate so as to form the PTC circuit protection chip device.