Flat Flexible Cable Terminal Crimping Design
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Solution Overview
Problem
The implementation of flat flexible cables (FFCs) in automotive applications is hindered by the need for quick, robust, and low-resistance termination techniques due to the fragile nature of thin foil conductors, leading to inconsistent electrical connectivity and mechanical unreliability in harsh environments.
Innovation Solution
A terminal design with a crimping portion featuring a base and foldable sidewalls, including protrusions and compression limiters, that securely crimps onto the conductor within an opening, ensuring reliable low-resistance connections by preventing conductor damage and ensuring consistent contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piercing-style crimp terminals are used to establish electrical connection with the embedded conductor, then the terminal can be manufactured and assembled, but the electrical resistance is much higher compared to conventional round wire F-crimps and electrical connectivity is inconsistent
Solution Approach 1:
The terminal is divided into distinct functional segments: a crimping portion with foldable sidewalls for mechanical attachment and an electrical contact portion for electrical connection. This segmentation allows each part to be optimized independently - the crimping portion provides consistent mechanical grip while the electrical contact ensures low-resistance connectivity, resolving the contradiction between connectivity consistency and electrical resistance.
Solution Approach 2:
The patent introduces an intermediary approach by using foldable sidewalls that progressively deform to crimp the conductor. This intermediate deformation process ensures consistent contact pressure and electrical connection, avoiding both excessive force that could damage the fragile conductor and insufficient force that would lead to high resistance or inconsistent connectivity.
2Reliability
If piercing-style crimp terminals are used to establish electrical connection with the embedded conductor, then the terminal structure can be implemented, but mechanical unreliability occurs over time in harsh environments
Solution Approach 1:
The terminal employs dynamic foldable sidewalls that can deform and adapt during the crimping process. This dynamic characteristic allows the sidewalls to conform to the conductor shape and maintain consistent contact pressure over time, even under thermal cycling and vibration in harsh environments, thereby improving mechanical reliability and service life.
Solution Approach 2:
The crimping portion is designed with inherent compliance and cushioning characteristics that protect the fragile conductor from excessive mechanical stress. This beforehand cushioning prevents conductor damage during installation and during subsequent thermal and mechanical cycling, ensuring long-term mechanical reliability in harsh environments.
3Strength
If the sidewalls are made rigid for strong crimping force, then the crimping strength is improved, but the thin foil conductor is damaged
Solution Approach 1:
The sidewalls are designed with controlled flexibility parameters that allow them to provide sufficient crimping strength while adapting to the thin foil conductor. By changing the material and geometric parameters of the sidewalls to achieve optimal compliance, the terminal can exert enough force for reliable electrical connection without exceeding the damage threshold of the fragile conductor.
Solution Approach 2:
The foldable sidewalls provide dynamic compliance during crimping, allowing the structure to adapt its stiffness characteristics. The sidewalls can deform progressively to distribute crimping force evenly across the conductor, preventing localized stress concentrations that would damage the thin foil while still achieving adequate crimping strength for reliable connection.
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 terminal design achieves reliable, low-resistance connections and mechanical stability by addressing the tolerance issues and fragility of thin conductors, enabling effective crimping operations in mass termination processes.
Implementation Method 1
The sidewalls are foldable over one another and into the opening for crimping the conductor within the opening and generally between the protrusion of the base and a portion of the sidewalls
Data Source
AI summary
A cable assembly includes a flat flexible cable having a plurality of conductors embedded within an insulation material. A portion of each of the conductors is exposed via openings selectively formed in the insulation material, allowing for a crimping portion of an electrically conductive terminal to engage with the conductor within the opening. The crimping portion of the terminal includes a base defining at least one protrusion extending therefrom, and first and second sidewalls extending from the base. The base and sidewalls define an opening configured to receive the conductor therein, wherein the sidewalls are foldable into the opening for crimping the conductor within the opening and generally between the protrusion of the base and a portion of the sidewalls.