I have put together a small guide on FFC cables found in LCD monitors. I hope someone finds it useful.


On some lcd's the ffc cable plugs into a LIF or ZIF socket.

On the LIF socket the cable is just inserted into the socket. This is the easiest to use but has no locking mechanism and the sockets are rated for a MAXIMUM of 10 insertions/removals (mating cycles). After this the socket may no longer work reliably.

On the ZIF socket their is a mechanical lock or slider that provides a retention mechanism for the cable. These allow the highest number of mating cycles. Although the number is higher it is still limited to about 30 cycles.

Why am I pointing this out?

It is easy to connect/disconnect cables using these sockets, and someone not aware of the lifecycle of these units may be tempted to disconnect/connect these cable frequently while determining the best setup for their lcd in the projector. Knowing these limits on the connectors may prevent someone from damaging their expensive LCD.

Some members of this forum have faced broken cables on their monitors. These cables are usually either FFC or FPC devices.

What is the difference?

Flat Flexible Cable (FFC's) is made up of thin
rectangular copper conductors laminated between
two layers of polyester insulation.

Flexible Printed Circuits (FPC's) are similar in construction
to the FFC except that copper film is chemically
etched to produce a specific pattern. These are custom made for each manufacturers specs. This means this type cable is nearly irreplacable with of the shelf items without modification (So be careful!).

I believe FPC's are what we are seeing with a variable pitch on each end. This would also make sense because from what I have researched FPC's are more fragile than the standard FFC cable and these seem to be the cables that are breaking in members monitors.

A new type which we hopefully wont see much off is the membrane FFC. These have a carbon/silver paste forming the trace and are very easily damaged.
The mating cycles for this material can be quite low. So if you run into this type be very cautious about handling it.

While FFC/FPC cable can are much more durable than they appear, several precautions must be observed.

1.) Never pull upward on the cable at the connectors. The cable and connection/connector is very vulnerable to breaking at these points

2.) Make sure conductors are lined up prior to inserting into socket. Misalignment can cause electrical damage and damage to the very small contacts.

3.)If the socket has a locking lever(ZIF) one must be very gentle with the locking arm as it will break very easily.

I am sure their are more precautions that I have forgot to add but I think you get the point. I hope this is helpful for DIYers new to the flat cable found in LCD monitors. My point of this is not to lecture but to hopefully prevent people from being discouraged from building a projector due to a damged LCD cable.

Condensing the whole in a few lines:

Guys! Don't screw around too much with FFCs/FPCs and their relative connectors and when you really have to do it, then be as careful as you would be if walking inside a nitroglicerin deposit ;P

Thanks for taking the time to post that info Wolfcreek. It will surely be a help in the future.

On the contrary, you've done us a lot of favors here, these are vey valuable info to know about these fragile cables. So thank you.

agreed im in my 3rd year of electrical engineering school at Purdue, and did not know that the FFC sockets had an short lived life span on the number of insertions .....

learn something new everyday ......

So how does one extend a LIF socket style connection? Thanks in advance to anyone who might know.

When working with FPC connectors I urge everyone to use extreme caution when bending the cable (to look at the back of it or when connecting a FFC extension (if the pitch of the FPC and FFC matches). These are very fragile and very little force is needed to create cracks in the copper plating. Many FPCs are soldered directly to the board so replacing/repair them is out of the question in those cases.

I would reccomend, before fiddling with a FPC connector, to tape both sides of it with scotch tape and if possible move the entire board instead of the FPC. Same goes for the LCD edge FFC's! Tape both sides of all the connectors so they can take a little more abuse over the years (months? )!

Cheers

Here are some pictures that I posted elsewhere that I thought would be helpful.


All of the LL FFCs are "same side" style, meaning that when you lay the FFC out flat the contacts on the ends are both on the same side of the cable.
Click to view attachment


"Opposite side" FFCs have the contacts on the topside on one end and on the opposite side on the other end.
Click to view attachment

If the original was opposite side, the LL FFC won't work as a replacement, but will work as an extension.


Also, make sure that you have unlocked the ZIF connector when you remove or insert an FFC cable. A lot of people don't know that these connectors have a locking feature on them, and the FFCs get damaged trying to pull them out or put them back into a connector that is locked.

pull-out type



flip-up type
Click to view attachmentClick to view attachment


Tgreenwood