Battery Module Bus Bar-FPC Connection Without Nickel Tabs
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Solution Overview
Problem
The increasing size of rechargeable battery modules leads to higher material and processing costs for flexible printed circuits (FPCs), and the use of nickel tabs increases process costs, necessitating a more cost-effective and efficient connection method between FPCs and bus bars.
Innovation Solution
A direct connection between the FPC and bus bar is achieved by bonding a soldering pattern of the FPC to a bus bar using a laser, eliminating the need for nickel tabs and utilizing aluminum foil to reduce material costs, while ensuring adequate resistance and peel strength through a structured expansion portion with through holes and soldering patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel tabs are used to connect FPC to bus bar, then connection reliability is improved, but material cost and process cost increase
Solution Approach 1:
The invention extracts and eliminates the nickel tab component from the connection structure. By directly bonding the FPC to the bus bar through laser welding, the intermediate nickel tab is removed, thereby reducing material cost and simplifying the manufacturing process while maintaining connection reliability
Solution Approach 2:
The invention merges the FPC and bus bar into a direct connection structure. The FPC is bonded directly to the bus bar without intermediate components, combining what were previously separate elements (FPC-nickel tab-bus bar) into a simplified direct bond (FPC-bus bar), reducing both material and process complexity
2Reliability
If FPC size is increased to accommodate larger battery modules, then voltage detection capability is improved, but material cost and processing cost increase
Solution Approach 1:
The invention introduces an expansion portion that extends in a direction perpendicular to the main body of the FPC. This dimensional extension allows the FPC to reach and connect to the bus bar on larger battery modules without increasing the overall FPC area proportionally, thereby maintaining voltage detection capability while controlling material costs
3Ease of manufacture
If direct connection between FPC and bus bar is implemented, then material cost is reduced, but connection quality and resistance control become more difficult
Solution Approach 1:
The invention applies local quality by creating an expansion portion with specific geometric features (through holes, enlarged area) at the connection location. This localized structural modification ensures adequate bonding area and laser welding quality at the critical connection point, while the rest of the FPC maintains its original simple structure
Solution Approach 2:
The FPC is designed with pre-formed through holes and an expansion portion structure before the bonding process. This preliminary preparation of the connection geometry ensures that when laser welding is applied, the bonding process can achieve consistent quality and controlled resistance values without requiring complex real-time adjustments
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 method reduces material costs and maintains or exceeds required resistance and peel strength, enabling reliable voltage detection without nickel tabs, thus enhancing the price competitiveness of rechargeable battery modules.
Implementation Method 1
bonding a soldering pattern of a flexible printed circuit (FPC) to a bus bar with a laser
Data Source
AI summary
A rechargeable battery module includes a bus bar holder covering battery cells; a bus bar on the bus bar holder to electrically connect the battery cells; and a flexible printed circuit on the bus bar holder to transmit a signal that detects a voltage of the battery cell connected to the bus bar. The bus bar includes an extension portion protruding in one direction, and the flexible printed circuit includes a main body portion, a branch portion extending from the main body portion, and an expansion portion having an expanded area on the branch portion that is soldered to the extension portion.