Extruded Flexible Flat Cable Insulator Crystallinity Control
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Solution Overview
Problem
Existing extruded flexible flat cables have reduced productivity and increased manufacturing costs due to low adhesive properties between conductors and insulators, leading to fragility under external stress, and poor bending characteristics due to crystallinity issues in polybutylene terephthalate resin.
Innovation Solution
An extruded flexible flat cable with conductors arranged side by side and an insulator provided by extrusion molding, where the insulator's tensile strength is equal to or greater than 47.2 MPa and percentage elongation is equal to or greater than 50/(0.5+2R) after a slide bending test, ensuring improved bending characteristics and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extrusion molding is used to provide an insulator around conductors, then productivity is improved and manufacturing cost is reduced, but adhesive property between conductors and insulator deteriorates, making the cable more fragile under external stress
Solution Approach 1:
The patent applies parameter changes by controlling the crystallinity of polybutylene terephthalate resin within a specific range (30-70%) through adjustments in cooling conditions and resin melting conditions during extrusion molding. This optimization of physical parameters achieves both high productivity through extrusion molding and sufficient adhesive property by preventing excessive crystallization that would cause brittleness.
2Productivity
If cooling speed is increased during extrusion molding, then productivity is improved, but crystallization is suppressed excessively, causing flexural modulus to decrease and making the insulator more prone to cracking during bending
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal range for crystallinity (30-70%) and controlling cooling conditions to achieve this range. By adjusting the cooling speed parameter within appropriate limits, the patent ensures sufficient crystallization to maintain flexural modulus and prevent cracking, while still allowing high enough cooling speeds to maintain productivity.
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 solution achieves an extruded flexible flat cable that can endure 100,000 times of slide bending or more with excellent bending characteristics, maintaining quality for automotive applications by optimizing insulator properties.
Implementation Method 1
The polybutylene terephthalate resin, used as the resin material in the extruded flexible flat cable of the related art, is a crystalline resin. Even the same resin has various degrees of crystallinity depending on cooling conditions and resin melting conditions during extrusion molding.
Data Source
AI summary
An extruded flexible flat cable includes conductors arranged side by side in a width direction of the extruded flexible flat cable. The conductors are spaced away from each other at a regular interval and an insulator is provided around the conductors by extrusion molding. A portion of the insulator located between the conductors, the portion having been sampled after the extruded flexible flat cable is subjected to a slide bending test, has a tensile strength being equal to or greater than 47.2 MPa. The portion has a percentage elongation being equal to or greater than 50/(0.5+2R), where R is a bend radius [mm] at which the extruded flexible flat cable is bent in the slide bending test.