Flexible Battery Pack Connection Pad for Cell Swelling Reliability
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Solution Overview
Problem
Existing battery packs face challenges in maintaining reliable electrical connections between connection lines and circuit boards, particularly under conditions of battery cell deformation such as swelling.
Innovation Solution
A battery pack design featuring a flexible connection line with a board connection pad that includes outer soldering portions, a gas discharge hole, and an inner soldering portion, which enhances coupling strength and stability even during battery cell deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional connection line structure is used, then the manufacturing process is simple, but the electrical connection reliability deteriorates under battery cell deformation
Solution Approach 1:
The connection line is divided into multiple functional segments: a link line for flexibility, a board connection pad with outer soldering portions for circuit board attachment, and an inner soldering portion for battery cell connection. This segmentation allows each part to optimize its function independently, improving overall reliability without excessive complexity.
Solution Approach 2:
Different regions of the board connection pad have different properties: outer soldering portions with concave shapes for strong circuit board attachment, an inner region with a gas discharge hole for soldering quality control, and an inner soldering portion for battery cell connection. This local differentiation ensures optimal performance at each connection point.
2Strength
If the board connection pad is enlarged to improve coupling strength, then the connection stability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The gas discharge hole is pre-formed in the inner region of the board connection pad before soldering. This preliminary action creates a controlled pathway for gas escape during soldering, ensuring reliable solder joint formation without requiring excessive precision in the final soldering step, while still achieving large pad area for strong coupling.
Solution Approach 2:
The gas discharge hole acts as an intermediary element that facilitates the soldering process. By providing a controlled gas escape path, it mediates between the large pad area (which improves strength) and the soldering process (which requires precision), allowing both goals to be achieved simultaneously.
3Adaptability or versatility
If the connection line is made flexible to accommodate cell deformation, then the adaptability improves, but the manufacturing complexity increases
Solution Approach 1:
The link line is designed as a flexible printed circuit board (FPCB) with thin film structure. This allows the connection line to bend and deform along with battery cell swelling or contraction, providing adaptability without requiring complex mechanical joints or adjustment mechanisms.
Solution Approach 2:
The flexible link line serves multiple functions: it provides electrical connection, accommodates cell deformation through flexibility, and maintains structural integrity. This multi-functionality reduces the need for additional components, keeping the overall structure relatively simple despite the adaptability requirement.
Data Source
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AI summary
A battery pack includes: a battery cell; a circuit board configured to collect state information about the battery cell; and a connection line configured to transmit the state information about the battery cell to the circuit board and including a link line and a board connection pad, wherein the link line extends from a side of the battery cell toward the circuit board, and the board connection pad extends from a first end portion, to which the link line is connected, and is coupled to the circuit board while facing the circuit board, wherein the board connection pad includes: outer soldering portions formed in an outer region of the board connection pad and concave toward the outside of the board connection pad; a gas discharge hole formed in a closed loop shape in an inner region of the board connection pad; and an inner soldering portion formed along the gas discharge hole. According to the present disclosure, the electrical connection between the connection line and the circuit board may be stably maintained with high reliability for transmitting state information about the battery cell, and manufacturing costs may be reduced by simplifying manufacturing processes.