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Top Reasons to Use Flat Cables Cheat Sheet (DRAFT) by [deleted]

Top Reasons to Use Flat Cables

This is a draft cheat sheet. It is a work in progress and is not finished yet.


Electrical engineers regularly turn to ubiquitous round-­profile cables and wires. They are common and what they know. Flat cables began develo­pment in the late 1950s to address the more demanding requir­ements arising in aerospace applic­ations. Engineers looking for an edge to improve product perfor­mance, reliab­ility, packaging, and manufa­cturing can benefit by adopting a wider use of flat cable.

1. Reliab­ility

The simplicity of flat cable with its parallel conductor geometry eliminates many of the sources of wiring errors and malfun­cti­ons.Co­ndu­ctors are registered one to one with the termin­ating connector or board so proper contact assignment is almost automatic.

2. Space

Electr­onics packaging continues to increase density. By nature of its shape, flat cable occupies roughly half the space of comparable round cable.

3. Weight Reduction

In addition to the reduction of unnece­ssary insula­ting, fillers and tapes, the composite flat-cable constr­uction is so mechan­ically strong that it is not necessary to have large conductors for strength. The copper cross-­section can thus be reduced to what’s required to carry the current load or to satisfy voltag­e-drop requir­ements

4. Consistent Electrical Charac­ter­istics

Because the conductor spacing is fixed and the geometry of the cable is constant, the electrical charac­ter­istics, such as impedance, capaci­tance, induct­ance, time delay, crosstalk, and attenu­ation are consis­tent.

5. Greater Current Carrying Capacity

Flat cables have greater surfac­e-t­o-v­olume ratio than their round cable counte­rparts, conseq­uently having higher efficiency in dissip­ating heat. This allows a higher current level for a given temper­ature rise and conductor cross-­sec­tion.

6. Flexib­ility

Flexib­ility is a key for any applic­ation involving motion, such as robotics, axis-c­ontrol manufa­cturing equipment, automated medical diagnostic equipment. Because conductors are aligned parallel in a flat plane, the bend radius of flat cable is a fraction of common round cables. Under repeated bending cycles, conductors in round cable can kink or “corks­crew” causing failure and reducing cycle life. Flat cable can provide 15-million flex-cycle life. For applic­ations with small bend radii and heavy flex cycling occurs, flat cable can provide a better solution.

7. Reduced Skewing Effects

Due to the conductors having the exact physical and electrical length, along with a continuous and consistent dielec­tric, time delays between signals within a given flat cable are minimized

8. High Density Connec­tions

Flat cable has a high wire-t­o-cable cross-­sec­tional density. So layers of flt cable pack more effici­ently and provide higher conductor density than round cables

9. Greater Strength

Flat cables have high strength because all conductors and insulators equally share tensile loads

10. Organi­zation and Handling

Flat cable has the ability to reduce the number of separate conductors that must be managed. Disparate conductor types, such as twisted pairs, single conduc­tors, coax, shielded and non-sh­ielded types—for power and signal—can be combined into a single flat cable.

A single flat cable containing a variety of conductors types can simplify design, assembly, and mainte­nance.
These benefits are inherent in flat cable and mostly unknown to the average design engineer. Flat cable is not always called for, but flat cable is more than just conductors in a different form factor. They provide a set of attributes that can solve many design challe­nges.