Reccomendations for fine pitch ribbon/flex/flat cable?

[Michael Noone]

Hi - I need to connect two PCBs together. They will move relative to each
other constantly. I'd like to find a fine pitch (maybe 1mm or so) flat
cable to connect between them - preferrably one that will be able to
tolerate this movement. I should mention this is not a production item -
under 10 of these will be made. I'd like it to be some sort of flat cable
that can easily have connectors added on to it.

So I see two major possibilities for connectors. The first I think is
called "insulation displacement connectors" - the kind of connector that
punches into a ribbon cable. The other possibility I see is what you often
see connecting the laser in an optical drive to the main board - where
there is a clear cable and the connector is just a stiffer bit on the end
of the cable. Is it possible to make such cables? Or does that have to be
done by machine?

Any suggestions? Thanks!

-M. Noone

 

[Pooh Bear]

Hi - I need to connect two PCBs together. They will move relative to each
other constantly. I'd like to find a fine pitch (maybe 1mm or so) flat
cable to connect between them - preferrably one that will be able to
tolerate this movement. I should mention this is not a production item -
under 10 of these will be made. I'd like it to be some sort of flat cable
that can easily have connectors added on to it.

So I see two major possibilities for connectors. The first I think is
called "insulation displacement connectors" - the kind of connector that
punches into a ribbon cable. The other possibility I see is what you often
see connecting the laser in an optical drive to the main board - where
there is a clear cable and the connector is just a stiffer bit on the end
of the cable. Is it possible to make such cables? Or does that have to be
done by machine?

I assume you're familiar with 0.05" pitch ribbon cable ?

There is a high density version on 0.025" pitch. I used it once where space
was *very* tight. Yamaichi made it under the 'Nanoflex' trade name. I'm sure
there are likely to be other suppliers now too.

We had the cable assemblies made by the supplier. I don't mind doing 0.05"
pitch in a machine vice but I reckon you're better off getting assemblies made
by the experts with the high density stuff.

Other possibilities exist but are unlikely to be practical for a qty of 10.

Graham

 

[Tim Hubberstey]

Hi - I need to connect two PCBs together. They will move relative to each
other constantly. I'd like to find a fine pitch (maybe 1mm or so) flat
cable to connect between them - preferrably one that will be able to
tolerate this movement. I should mention this is not a production item -
under 10 of these will be made. I'd like it to be some sort of flat cable
that can easily have connectors added on to it.

So I see two major possibilities for connectors. The first I think is
called "insulation displacement connectors" - the kind of connector that
punches into a ribbon cable. The other possibility I see is what you often
see connecting the laser in an optical drive to the main board - where
there is a clear cable and the connector is just a stiffer bit on the end
of the cable. Is it possible to make such cables? Or does that have to be
done by machine?

IDC cables are, generally, not intended to be used in applications where
they will be subjected to a lot of flexing. The 0.025" stuff is even
less flexible.

There are stock flex cables available from several manufacturers. These
are standard versions using similar construction to your "laser cable".
Take apart any laptop and you'll probably see a bunch of them.

There are 2 main versions (and many variations):
1. Has pins crimped onto both ends for soldering directly onto PCB or
inserting into connectors.
2. Has flat, tinned pads at the cable ends. Mates with a connector that
looks similar to a PCB edge connector but has a locking mechanism to
hold the cable.

My guess is that type 2 will probably stand up to repeated flexing
better than the type 1. For examples of both cables and connectors, see
pages 52 & 53 of the *Canadian* Digi-Key catalog:

http://dkc3.digikey.com/PDF/C052/0052.pdf
http://dkc3.digikey.com/PDF/C052/0053.pdf

I assume the US catalog has the same (or similar) parts available.