Battery Pack Connection Pad Venting for Swelling-Stable PCB Soldering
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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 swelling, and require complex manufacturing processes that increase costs.
Innovation Solution
A battery pack design featuring a connection line with a board connection pad that includes outer and inner soldering portions, a gas discharge hole, and an insulating layer, which enhances coupling strength and allows for integrated reflow soldering of connection lines and circuit elements, simplifying manufacturing and reducing costs.
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 swelling conditions
Solution Approach 1:
The connection line is divided into multiple functional segments: a link line portion connecting to the battery cell, a board connection pad portion for PCB mounting, outer soldering portions for electrical connection, and an inner soldering portion surrounded by a gas discharge hole. This segmentation allows each part to perform its specific function optimally, improving overall connection reliability while maintaining manufacturing feasibility through standardized processes.
Solution Approach 2:
Different regions of the board connection pad are given different properties: the outer region has soldering portions for electrical connection to the PCB, the inner region has a gas discharge hole for venting trapped gas during soldering, and specific areas have enhanced solder wettability. This local differentiation ensures reliable soldering while preventing defects, directly addressing connection reliability without requiring complex overall restructuring.
2Ease of manufacture
If separate soldering processes are used for connection lines and circuit elements, then connection reliability is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The board connection pad is designed to enable both the connection line and circuit elements (such as resistors, capacitors, and ICs) to be soldered to the PCB in a single reflow soldering process. The pad structure includes outer soldering portions that accommodate both the connection line and circuit elements, allowing them to be mounted and soldered simultaneously. This merging of processes simplifies manufacturing while maintaining connection reliability through consistent soldering conditions.
Solution Approach 2:
The board connection pad serves multiple functions: it provides electrical connection for the connection line, serves as a mounting platform for circuit elements, enables simultaneous reflow soldering for both, and includes a gas discharge hole to prevent soldering defects. This multi-functionality allows a single structure to replace what would traditionally require separate processes, improving ease of manufacture while preserving reliability.
3Manufacturing precision
If the board connection pad lacks a gas discharge hole, then the structure is simpler, but soldering defects occur due to trapped gas
Solution Approach 1:
A gas discharge hole is extracted from the board connection pad structure, creating a dedicated pathway for trapped gas to escape during the reflow soldering process. This hole is strategically positioned in the inner region of the pad, surrounded by the inner soldering portion, to allow gas venting without compromising the electrical connection function. The simple circular or oval opening adds minimal structural complexity while dramatically improving soldering quality by preventing voids and defects.
4Reliability
If the connection line structure is optimized for reliability, then connection stability improves, but manufacturing cost increases
Solution Approach 1:
The board connection pad uses standard PCB fabrication parameters and materials, with the conductive pattern and insulating layer formed through conventional photolithography and lamination processes. The outer and inner soldering portions are created by exposing the conductive pattern in specific regions, using standard solder mask and stencil printing techniques. The gas discharge hole is drilled and plated using standard PCB manufacturing methods. These parameter choices maintain connection stability while avoiding costly custom processes or materials.
Data Source
AI summary
This application relates to a battery pack including 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. 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. 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 and a gas discharge hole formed in a closed loop shape in an inner region of the board connection pad.