Author Topic: joints in ribbon cable  (Read 2121 times)

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Offline m4rtinTopic starter

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joints in ribbon cable
« on: August 15, 2015, 01:47:07 am »
I have a ribbon cable which has following joints and traces seem to switch side:



What is the reason for those joints?
 

Offline ataradov

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Re: joints in ribbon cable
« Reply #1 on: August 15, 2015, 01:56:24 am »
It is possible that designers needed to have exposed ends on different sides of the cable and could not simply bend it over mechanically.
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Offline m4rtinTopic starter

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Re: joints in ribbon cable
« Reply #2 on: August 16, 2015, 06:53:32 pm »
It is possible that designers needed to have exposed ends on different sides of the cable and could not simply bend it over mechanically.

I see. I think you are correct. However, why aren't those traces conductive at both sides?
 

Offline ataradov

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Re: joints in ribbon cable
« Reply #3 on: August 16, 2015, 07:09:21 pm »
Why would they do that? You'd still need to have vias, but now your connectors also have exposed copper on both sides. And that's probably not what is specified in a documentation for the mating part.
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Offline T3sl4co1l

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Re: joints in ribbon cable
« Reply #4 on: August 17, 2015, 01:36:50 pm »
FYI, "ribbon cable" refers to a multi-conductor cable made from wires molded into a common (usually corrugated, so it can be cut easily) plastic insulator.  What you've got there is FPC (Flexible Printed Circuit), or "flat flex", etc.

Not to say you're wrong by calling it that (it does appear to be cabling, and is in the shape of a ribbon), just what the proper term is. :)

Indeed, they could've chosen to put quite a lot more on there (including components and active circuitry!), but often this is not needed.

The traces are not "conductive both sides" because the material is constructed much like ordinary PCBs are: a carrier film (made of Kapton, hence the gold color) has copper foil on both sides; is etched, drilled and plated; and sealed with a cover layer (again Kapton, but could be other kinds of solder mask).

Tim
« Last Edit: August 17, 2015, 01:38:35 pm by T3sl4co1l »
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