PCB-FPCB Conductive Bonding for Battery Module Stress Reliability
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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 lead to deformation and reduced contact area between circuit terminals.
Innovation Solution
The use of an anisotropic conductive film with conductive metal particles like nickel, Sn-Bi alloy, and Sn-Au-Cu alloy, combined with a thermosetting resin and silica, to form 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 connection and structural stability under severe conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anisotropic conductive film is used to bond PCB and FPCB, then the bonding process is simple, but the electrical bonding reliability deteriorates under harsh environmental conditions and mechanical stress
Solution Approach 1:
The patent uses a composite anisotropic conductive film containing thermosetting resin, conductive metal particles, and silica filler. This composite structure provides both electrical conductivity and mechanical strength, enabling the bonding to withstand harsh environmental conditions and mechanical stress while maintaining reliable electrical connection between PCB and FPCB.
Solution Approach 2:
The patent optimizes the degree of curing of the thermosetting resin to 70-97%, which is higher than conventional fully cured (100%) resin. This partial curing state maintains the resin's flexibility and adhesion properties while providing sufficient structural support, thereby improving bonding reliability under thermal and mechanical stress without compromising electrical connection.
2Reliability
If the contact area between circuit terminals is increased to improve electrical bonding, then the electrical connection is enhanced, but the structural complexity increases
Solution Approach 1:
The patent introduces silica filler particles as an intermediary within the anisotropic conductive film. These particles act as spacers and structural support elements that increase the effective contact area between circuit terminals while maintaining a simple single-layer bonding structure. The silica filler enhances both electrical connection and mechanical stability without adding complex multi-layer structures.
3Stability of the object's composition
If a thermosetting resin with high degree of curing is used to maintain structural stability, then the structural integrity is improved, but the adhesion and flexibility deteriorate
Solution Approach 1:
The patent precisely controls the degree of curing of the thermosetting resin to be within 70-97%, rather than complete curing. This parameter optimization maintains adequate structural integrity while preserving sufficient adhesion and flexibility. The partially cured resin continues to exhibit tackiness and conformability, ensuring strong bonding to the circuit board surfaces while providing mechanical flexibility to withstand stress.
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 reliability of electrical bonding between PCBs and FPCBs by increasing the contact area and maintaining structural integrity, even under dynamic temperature and humidity conditions, and mechanical stress, thereby improving the overall stability of the battery module.
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 ultrasonic welding
Implementation Method 3
The bonding of the PCB to the FPCB may be performed by thermal fusion
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
Data Source
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 a 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.