Flexible Printed Circuit Bus Bars Battery Cell Pitch Adaptation
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Solution Overview
Problem
Conventional connection methods for battery cells and monitoring circuits, such as wire harnesses, flexible flat cables, and rigid substrates, face challenges including complexity, weight, miniaturization difficulties, and declining productivity as the number of battery cells increases, especially in large-scale battery systems like fuel cells.
Innovation Solution
A flexible printed circuit with bus bars is developed, featuring a flexible insulating base material with wiring patterns and land parts for bus bar connection, where bus bars are fixed and electrically connected using a plating layer, allowing for easy assembly and miniaturization, and reducing the need for individual electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wire harness is used to connect battery cells and monitoring circuits, then the connection is reliable, but the number of components increases, assembly becomes complicated, and the weight of the battery system increases
Solution Approach 1:
The patent combines multiple separate connection functions into a single integrated flexible printed circuit board. The FPC integrates both the power connection function (through bus bars) and the monitoring circuit function (through integrated circuits mounted on the FPC), eliminating the need for separate wire harnesses and reducing component count while maintaining reliable electrical connections
2Ease of operation
If a flexible flat cable is used for connection, then the assembly is more flexible, but it is difficult to provide a monitoring circuit on the cable and miniaturization is difficult
Solution Approach 1:
The patent merges the flexible flat cable structure with integrated circuits and bus bars into a single multi-functional FPC assembly. This integration allows the monitoring circuits to be mounted directly on the flexible substrate, enabling both assembly flexibility and system miniaturization simultaneously
Solution Approach 2:
The flexible printed circuit board serves multiple functions: it provides mechanical flexibility for assembly, acts as a substrate for mounting monitoring circuits, provides electrical connections through integrated circuits, and connects to battery cells via bus bars. This multi-functionality resolves the contradiction by making the single component capable of performing all required functions
3Stability of the object's composition
If a rigid substrate is used for connection, then the structural stability is good, but it is not easy to assemble to a battery block due to variation in inter-electrode pitch
Solution Approach 1:
The patent replaces the rigid substrate with a flexible printed circuit board that can dynamically adapt to variations in inter-electrode pitch. The flexible nature of the FPC allows it to bend and conform to the actual positions of battery cell electrodes, ensuring reliable electrical connections even when pitch variations occur, while the laminated structure provides sufficient structural stability
4Reliability
If bus bars are electrically connected one by one by screwing or welding, then the connection is reliable, but productivity declines as the number of battery cells increases
Solution Approach 1:
The patent combines multiple individual bus bar connections into a single integrated FPC assembly where multiple bus bars are pre-attached to the flexible circuit board. This allows all bus bars to be connected to the battery cells simultaneously in one assembly operation rather than requiring individual connection of each bus bar, significantly improving productivity while maintaining reliable electrical connections through the integrated plating layer
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 flexible printed circuit with bus bars enables a small-sized, lightweight, and easily assembled battery system that maintains productivity even with a large number of battery cells, facilitating miniaturization and improving reliability through duplexed wiring patterns and reduced component count.
Implementation Method 1
the plurality of bus bars are electrically connected to the respectively corresponding land parts for the bus bar connection in block by a plating layer formed on the bus bars and the land parts for the bus bar connection
Data Source
AI summary
To be small-sized/light in weight, and to easily cope with the variation of an inter-electrode pitch of battery cells. A flexible printed circuit with bus bars of one embodiment includes a flexible printed wiring board having a flexible insulating base material and a plurality of wiring patterns provided on one main surface of the flexible insulating base material and provided with land parts for bus bar connection at one end, and a plurality of bus bars and fixed to the land parts for the bus bar connection with an adhesive. The plurality of bus bars and are electrically connected to the respectively corresponding land parts for the bus bar connection in block by a plating layer formed on the bus bar and the land part for the bus bar connection.