PCB-FPCB Conductive Bonding for Reliable Battery Module Connections
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Solution Overview
Problem
Existing anisotropic conductive film technologies struggle to maintain reliable electrical bonding between printed circuit boards (PCBs) and flexible printed circuit boards (FPCBs) in electric vehicle battery modules due to harsh environmental conditions, such as temperature and humidity variations, and mechanical stress, which can deform the bonding portion and reduce contact area between circuit terminals.
Innovation Solution
The use of an anisotropic conductive film with conductive metal particles, such as nickel, Sn-Bi alloy, and Sn-Au-Cu alloy, along with a thermosetting resin and silica, to create a conductive bonding portion with a high degree of curing, which includes a solder with a higher melting temperature than the resin, ensuring stable electrical connections under severe conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anisotropic conductive film is used for bonding PCB and FPCB, then electrical connection is achieved, but bonding reliability deteriorates under harsh environmental conditions and mechanical stress
Solution Approach 1:
The patent uses a composite bonding structure consisting of anisotropic conductive film with conductive metal particles (nickel, Sn-Bi alloy, Sn-Au-Cu alloy) dispersed in thermosetting resin, combined with silica filler. This composite material provides both electrical conductivity and mechanical strength to maintain bonding reliability under harsh environmental conditions and mechanical stress.
Solution Approach 2:
The patent optimizes the degree of curing of the thermosetting resin to 70-97%, which balances the resin's flexibility and structural stability. This parameter control ensures the bonding portion can withstand mechanical stress while maintaining electrical connection reliability under temperature and humidity variations.
2Strength
If high degree of curing is achieved in thermosetting resin, then bonding strength is improved, but flexibility of the bonding portion deteriorates
Solution Approach 1:
The patent controls the degree of curing of the thermosetting resin within the range of 70-97%, optimizing the balance between bonding strength and flexibility. This partial curing approach maintains sufficient structural strength while retaining enough flexibility to accommodate mechanical stress and thermal expansion in battery modules.
3Reliability
If conductive metal particles are used for electrical connection, then electrical conductivity is achieved, but contact area between circuit terminals is reduced under mechanical stress
Solution Approach 1:
The anisotropic conductive film contains conductive metal particles dispersed in thermosetting resin, creating a porous-like structure that allows multiple contact points between PCB and FPCB. This structure maintains electrical connection reliability even when contact area is reduced under mechanical stress, as the conductive particles can deform and maintain contact.
Solution Approach 2:
The combination of conductive metal particles (nickel, Sn-Bi alloy, Sn-Au-Cu alloy) with thermosetting resin and silica filler creates a composite material that maintains both electrical conductivity and mechanical compliance. This composite structure ensures stable electrical connection under mechanical stress while preserving sufficient contact area.
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 approach enhances the bonding strength and reliability of electrical connections between PCBs and FPCBs, maintaining stability even under dynamic temperature and humidity conditions and mechanical stress, thereby improving the overall performance of electric vehicle battery modules.
Implementation Method 1
a heating and pressurizing process of applying a predetermined pressure while applying heat or ultrasonic waves under predetermined conditions may be performed to cure the resin
Implementation Method 2
The bonding of the PCB to the FPCB may be performed by thermal fusion
Implementation Method 3
The bonding of the PCB to the FPCB may be performed by ultrasonic welding
Implementation Method 4
the copper pattern of the PCB and the copper pattern of the FPCB are electrically connected to each other by a conductive metal particles
Implementation Method 5
a heating and pressurizing process of applying a predetermined pressure while applying heat or ultrasonic waves under predetermined conditions may be performed
Data Source
Figure 1~2
Figure 3~4
AI summary
A battery module includes a printed circuit board (PCB) having a copper pattern; a flexible printed circuit board (FPCB) having a copper pattern; and a conductive bonding portion for bonding the PCB to the FPCB, wherein the copper pattern of the PCB and the copper pattern of the FPCB are electrically connected to each other by conductive metal particles, and wherein at least one of the copper pattern of the PCB and the copper pattern of the FPCB has at least one or more alloy layers selected from a group consisting one or more of Ni-Sn and Au-Ni-Sn-Bi.