Resistor Connector Avoids Solder Cracks in Current Detector
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Solution Overview
Problem
The increase in resistance value due to temperature cycles in resistors, particularly in electrochemical devices like batteries, poses a challenge as it affects the accuracy of state of charge estimation and can lead to solder cracks when using solder bonding through holes.
Innovation Solution
A current detector configuration where the resistor is electrically connected to a printed circuit board via a connector without solder bonding, using a second terminal that is brought into contact with a first terminal, thereby avoiding solder cracks and reducing the number of parts needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If terminals of the resistor are made to pass through through holes and are directly fixed to the printed circuit board by soldering, then the screw fixing operation becomes unnecessary and the number of parts can be decreased, but due to the repetition of temperature cycle caused by generation of heat in the resistor, there is a possibility that a solder crack occurs in a bonding portion between the printed circuit board and the resistor so that a resistance value is increased
Solution Approach 1:
The patent introduces a connector as an intermediary component between the resistor and the printed circuit board. The connector includes a first terminal that contacts the second terminal of the resistor and a second terminal that connects to the printed circuit board, thereby mediating the electrical connection and avoiding direct solder bonding of the resistor to the board, which resolves the technical contradiction by maintaining reliability while reducing device complexity.
Solution Approach 2:
The patent segments the electrical connection path into distinct components: the resistor, the connector with its first and second terminals, and the printed circuit board. This segmentation allows each component to perform its specific function independently, with the connector serving as a separate element that facilitates connection without requiring solder bonding of the resistor itself to the board.
2Ease of manufacture
If terminals of the resistor are made to pass through through holes and are directly fixed to the printed circuit board by soldering, then the screw fixing operation becomes unnecessary, but the mounting operability becomes poor
Solution Approach 1:
The connector acts as an intermediary that simplifies the mounting process. Instead of directly soldering resistor terminals to the printed circuit board through holes, the connector provides a standardized interface that can be mounted using conventional techniques, thereby improving mounting operability while managing device complexity.
3Reliability
If a connector is introduced to electrically connect the resistor to the printed circuit board without solder bonding, then the increase of resistance value due to temperature cycles is suppressed, but the number of parts increases
Solution Approach 1:
The connector serves as a mediator that protects the resistor from direct thermal and mechanical stress of soldering processes while maintaining electrical connection. Although it adds a component, it significantly improves reliability by preventing solder cracks that would otherwise increase resistance values during temperature cycling.
Solution Approach 2:
The patent replaces the mechanical solder bonding system with a connector-based electrical connection system. This substitution eliminates the need for high-temperature soldering processes that cause thermal expansion and contraction, thereby preventing solder cracks and maintaining stable resistance values throughout the product lifecycle.
Data Source
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AI summary
A current detector includes: a printed circuit board; and a resistor for detecting an electric current of the electrochemical device, wherein a connector having a first terminal is mounted on the printed circuit board, and the resistor has a second terminal which is brought into contact with the first terminal.