Thin Over-Current Protection Device with Bevel
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Solution Overview
Problem
Conventional over-current protection devices are thick due to their structure, making it difficult to achieve a thinner form that is necessary for compact electronic apparatuses, as they typically require multiple PTC devices connected in parallel to meet low-resistance requirements.
Innovation Solution
The design features a thin-type over-current protection device with a quadrilateral structure that includes a bevel on one side surface, allowing for a reduced number of insulation layers and conductive members, enabling the use of single or multiple PTC material layers to achieve a thinner profile while maintaining low resistance, with electrodes and conductive members strategically positioned for efficient connection and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two stacked PTC devices are connected in parallel to lower the resistance, then the resistance requirement is met, but the device thickness increases
Solution Approach 1:
The patent transitions from a vertical stacking arrangement (thickness direction) to a lateral parallel arrangement (planar direction). The PTC devices are positioned side-by-side with their long edges parallel to each other, allowing electrical connection through conductive members at the ends rather than through vertical stacking. This dimensional reorganization maintains low resistance while reducing device thickness.
Solution Approach 2:
The patent divides the PTC devices into distinct segments positioned laterally rather than stacked vertically. Each PTC device is a separate entity with defined boundaries, connected through conductive members. This segmentation allows the devices to be arranged in a space-efficient configuration that reduces overall thickness while maintaining the parallel connection for low resistance.
2Reliability
If multiple insulation layers and conductive members are added to connect stacked PTC devices, then electrical connection is achieved, but device complexity and thickness increase
Solution Approach 1:
The patent merges the insulation and connection functions into a simplified structure. The lateral arrangement allows conductive members to serve both as electrical connectors and as part of the overall device architecture, reducing the need for separate insulation layers between stacked components. The structure integrates these elements more efficiently, lowering overall complexity.
Solution Approach 2:
The patent extracts the insulation layers from between stacked PTC devices and repositions them laterally. By removing the vertical stacking arrangement, the complex multi-layer insulation structure is eliminated and replaced with a simpler lateral configuration where insulation is provided only where necessary for electrical isolation, significantly reducing structural complexity.
3Reliability
If external electrodes are added to connect the over-current protection device to the PCM board, then electrical connection is achieved, but the device occupies more space
Solution Approach 1:
The conductive members that connect the PTC devices laterally also serve as the external electrodes for connection to the PCM board. This multi-functional design eliminates the need for separate external electrode structures, allowing the same components to fulfill both internal connection and external interface functions, thereby reducing the overall device area.
Solution Approach 2:
The patent utilizes the lateral dimension for both PTC device arrangement and external connection points. By positioning the conductive members at the ends of the laterally arranged PTC devices, the external electrodes are integrated into the same plane, maximizing space utilization and minimizing the occupied area compared to traditional vertical stacking with separate external electrodes.
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 design effectively thins the over-current protection device to below 0.7 mm, meeting the requirements of compact electronic apparatuses while sustaining low resistance, thus enabling its application in smaller electronic devices.
Implementation Method 1
The resistive material has positive temperature coefficient (PTC) characteristic that the resistance thereof remains extremely low at room temperature and instantaneously increases to thousand times when the temperature reaches a critical temperature or the circuit has over-current
Data Source
AI summary
An over-current protection device is of an approximately quadrilateral structure with upper and lower surfaces, first and second side surfaces, in which the second side surface contains a bevel. The device comprises first and second electrodes, a first PTC material layer, and first and second conductive connecting members. The first electrode is formed on the upper or lower surface. The second electrode is formed on the lower surface and is insulated from the first electrode. The first PTC material layer extends along the upper surface, and has a first surface electrically coupled to the first electrode, and a second surface electrically coupled to the second electrode. The first conductive connecting member is formed on the first side surface and is electrically coupled to the first electrode. The second conductive connecting member is formed on the second side surface and extends along the bevel to electrically couple to the second electrode.