Over-current Protection Device Bonding Strength via Lateral Extension
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Solution Overview
Problem
The existing over-current protection devices with positive temperature coefficient (PTC) behavior suffer from poor bonding strength with circuit boards, leading to peeling during assembly due to torque and tension, and require specific soldering areas for external electrode connection.
Innovation Solution
The design includes a rectangular cuboid over-current protection device with a PTC material layer, electrode foils, bonding sections, and metal connecting members that securely bond to the circuit board, allowing for soldering or welding without a dedicated soldering area, and features a full-surface electrode design for easy external connection, enhancing bonding strength and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the PTC device is soldered onto the circuit board using conventional methods, then the assembly process is simple, but the bonding strength is insufficient and the device may peel off during sequential assembly
Solution Approach 1:
The bonding section extends from the lower surface laterally along the lateral surface of the PTC device, transitioning from a two-dimensional surface bonding to a three-dimensional structural interlocking. This dimensional extension allows the bonding section to engage with joint sections on the circuit board in multiple directions, significantly enhancing bonding strength while maintaining ease of manufacture through conventional soldering processes.
2Manufacturing precision
If a specific soldering area is designated for external electrode connection, then the connection precision is high, but the device complexity increases and manufacturing efficiency decreases
Solution Approach 1:
The entire upper surface of the PTC device is designed as a universal bonding interface that can function as both the protective surface and the external electrode connection area. This multi-functional design eliminates the need for specific designated soldering areas, allowing connections at any location on the upper surface while maintaining manufacturing precision and reducing device complexity.
3Device complexity
If the PTC device structure is simplified to reduce manufacturing complexity, then the device complexity decreases, but the bonding strength and reliability are compromised
Solution Approach 1:
The PTC device is segmented into functionally distinct components: the PTC material layer for over-current protection, the electrode foils for electrical connection, and the bonding section for mechanical attachment. This segmentation allows each component to be optimized for its specific function while maintaining overall structural simplicity. The bonding section's lateral extension provides enhanced reliability without adding complex multi-layer structures.
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 effectively prevents peeling of the over-current protection device from the circuit board during assembly and allows for efficient connection to external electrodes without precise positioning, thereby improving manufacturing efficiency and bonding strength.
Implementation Method 1
The present application relates to an over-current protection device, and a protective circuit board on which the over-current protection device is disposed. The over-current protection device exhibits positive temperature coefficient (PTC) behavior.
Implementation Method 2
The bonding section and metal connecting member connect to corresponding joint sections of the circuit board by soldering.
Data Source
AI summary
An over-current protection device adapted to be soldered onto a circuit board comprises a PTC material layer, a first electrode foil, a second electrode foil, a bonding section and a metal connecting member. The PTC material layer has opposite first and second surfaces. The first electrode foil is in physical contact with the first surface, and the second electrode foil electrically connects to the second surface. Both the second electrode foil and the bonding section are disposed on bottom of the device, and the bonding section is separated from the second electrode foil. The metal connecting member is disposed on the lateral surface of the device. The second electrode foil is adapted to be soldered onto an electrode section of the circuit board. The bonding section and the metal connecting member connect to corresponding joint section of the circuit board.