tft lcd pcb connection fpc manufacturer

FPCs are typically used with a ZIF connector to connect to a PCB. When looking for a compatible ZIF connector for a given FPC, it is important to consider the pitch (spacing of the pins), the number of pins, whether the connector has contacts on the top, bottom, or both, and the material of the connectors on the FPC and the ZIF connector.

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Let’s face it, full-colour TFT displays are cool and adding one to your project is going to instantly endow your project with coolness. The problem for the hobbyist is that they come with flexible flat connectors known as FPC or FFC connectors. These are designed to be soldered to a PCB using a ‘hot-bar’ device that is pressed across all the terminals at once, instantly soldering them to the board. Nice if you’ve got one.

Help is at hand. There are many suppliers on ebay that will sell you a small TFT already mated to a PCB with the FPC connector broken out into a 2.54mm DIP header. If these satisfy your needs then buy them, you’ll be saving yourself a whole lot of work.

But what if the panel you want only comes ‘naked’, or perhaps you want to drive the signals directly as you’ll have to do if you want to stream video to it. If you fall into these categories then you are going to have to tackle the FPC connector yourself, and I’m going to show you how.

The breakout board is suitable for many different FPC pin pitches. By holding the FPC connector up against the board I can see that mine has a 0.8mm pitch and 37 terminals. As a bonus I can see that each terminal has a very small hole punched in it. This hole is designed to allow solder to flow up from underneath, making a better connection.

We are going to use a reflow technique to solder this connector. The idea is that we lay down solder on to the board pads and then reflow it to create the connection. I was surprised how easy this was.

Now is a great time to solder the DIP header into place because you’re not going to be able to get to it easily after the FPC connector has been soldered down.

Before starting on the FPC connector make sure you paste a thin layer of flux over the tinned board connectors. This will help the solder to reflow smoothly over the FPC terminals.

Working under the microscope or magnifier, carefully align the FPC connector with the tinned pads ensuring that it’s straight and that each terminal is completely overlapping the pad. Don’t overlap the pad more than the terminal length because there may be some traces further back on the connector that could cause a short circuit. Hold it down like that with one of your hands.

This instructable came about from a broken LCD control module out of a modern VW Camper Van. The LCD module is part of a control unit which was virtually unreadable and a replacement for a new unit was £400+. It really was a no lose option, either have a go at fixing it or end up buying a new unit.

The fault of the LCD was that it only displayed a couple lines of output on the LCD. The symptoms are caused by poor location of the LCD ribbon in manufacture and also the poor position of the whole module in the vehicle which exposes it to heat and is subject to vibration within the vehicle. This causes the ribbon to fail eventually and is a known common fault.

The ribbon in this display actually controls the Rows of the LCD matrix and the Columns were handled by a rubber standoff connection on the longest side of the LCD. There were no problems with the rubberized connection.

Some re-work on the LCD ribbon had already been tried with a little improvement but the poor registration of the ribbon pushed me to try a new attachment.

From the photos below you can see the LCD control unit and the state of the LCD ribbon before repair. You can just make out the offset placement and poor registration of the ribbon before repair.

The registrations of the LCD ribbon in this repair was difficult. It took me and my friend 20 minutes just to line up the ribbon for re-attachment. The ribbon in this case is sub 1mm pitch OR less than 25.4 thousands of an inch. You may want to try a simpler ribbon repair on an old LCD clock for example before jumping in head first with fine pitch.

Also the removal of the LCD ribbon is a delicate process as you do not want to tear what is a good ribbon or damage the carbon printed lines. Also the PCB must be respected to avoid introducing other faults and the the re-attachment may need an extra pair of hands.

You may also want to review the last step for results and lessons learned from this instructable before jumping in head first but i believe this will give a you a good insight to some important factors of LCD ribbons and possible success.

Other favorites of reworking the LCD connection that i have read here are the tinfoil on a heat gun. This has good temperature management but not so good in tight spaces. The solder iron with flat blade and tin foil is more precise but a 25 Watt iron can be too brutal on the ribbon.

3. Is the Ribbon continuity visibly good, by that i mean the carbon connection lines are continuous and unbroken - Do check otherwise you may be wasting your time.

In the photos below you can see the available ribbon length was generous enough but do watch for mechanical constraints. In some cases you could find yourself not being able to lay down the LCD back down as it is too tight a radius to sit down.

You do not want to pull at the ribbon as you will most likely damage what you already have. In my instance it was best to cut the ribbon free as close to the PCB pads as possible.I used a scalpel to slice parallel to the PCB board to remove the ribbon. Do make a good job of this as you may need to preserve as much extra ribbon to re-attach the LCD module.

The LCD assembly was lifted off and put in safe place to avoid damage. The ribbon was then gently lifted and peeled back with tweezers to remove the bulk. You must not use force to remove the remainder ribbon especially if your PCB is off a cheap quality OR single sided cardboard type variety. The PCB pads can come off with the ribbon! If you have a double sided PCB of FR4

If you have a half decent PCB the connecting pads may be gold flashed (actually called Electroless Plated gold). This gold flashing is good as it provides a very good flatness to the PCB pads but they are not as mechanically strong as gold edge connectors (like you see on old PC adapter cards) which is a hard gold . The gold plate here is soft and also micrometer thin on the surface.

For either connection style  you need to remove any old glue from the ribbon and remaining carbon debris from the pads. I used isopropanol on a cotton wool bud. Do not flood the PCB with cleaning fluidas you may effect electro-mechanical elements in close proximity such as switches and other items on the PCB which are not sealed against cleaning!

The PCB pads must be thoroughly cleaned and no debris must exist. Use you X10 OR x20 eyepiece here to check how clean the  pads are. The PCB pads need to be pristine and nothing less.

From the photos you can see the PCB pads before cleaning through the eyepiece and the final photo shows the clean PCB pads with leftover cotton wool buds.

From the photos you can see that ribbon was trimmed with a rounded scalpel blade.  The ribbon also had extra green tape which adhered to the original heel of the PCB pad connection. This gave extra mechanical stability for the ribbon but has to be peeled off to allow for re-connection. Later in this instructable i will mention about putting back extra mechanical stability for ribbon support.

If you have a fine pitch ribbon like i had this will cause you the most trouble. I needed an extra steady pair of hands to help and some patience before i got the the ribbon aligned. It took twenty minutes of nudging the PCB and ribbon to get a precise alignment. Our alignment was actually better than the original which was slightly skewed to one side.

The trick to get good alignment is to allow some the gold pad fingers toes of  the PCB to be visible just beyond the carbon lines of the ribbon. You then get the pads toes to line up with the carbon lines of the LCD ribbon.

Do not continue until you have excellent alignment of the black carbon lines of the ribbon to the PCB pads. The finer the pitch of the ribbon the better registration is required.

The photos below show how i handled the PCB and LCD and clamped the ribbon in place. The LCD display is being held by a plastic clamp above the PCB assembly. The PCB below which has components both sides is laying on some foam (try polystyrene). This allowed me to nudge the PCB under the ribbon into position. The plastic ruler acts as a LCD ribbon clamp. When you have got the registration get a steady handed friend to hold the ruler as a ribbon clamp in place so you can then apply the heat to stick the ribbon back down.

You may want to skip forward to the next step to see the re-attached picture of the ribbon and to see how the alignment was achieved. You should see the gold PCB pad finger toes in line with the carbon of the ribbon

In our case the LCD ribbon was not only glued to the PCB pads but there was some additional tape at the heel of the ribbon to hold the ribbon in place. By holding at the heel the ribbon you get some good extra mechanical support.

I did not go further with more re-work as the VW LCD module was considered a good enough result and some other time pressures intervened. It was concluded that we could read the display well enough and operate items from the controller. It was also considered as one of those quit while your ahead things!

The technique for LCD ribbon removal and re-attachment are achievable certainly on simpler ribbons and fine pitch ribbons with careful preparation and thought. I hope this instructable is comprehensive enough for people to get some good results.

The ribbon is know as a "Heat Seal Connection" OR "HSC". In the industry heat and pressure are used to make this type of connection. The material comes from a family of "Anisotropic Conductive Films" OR "ACF".

The material bonds at 180 DegreeC. Direct Ribbon connection is used for economy (i.e. no fancy connectors) and for the number of connections its offers in a small footprint which would not be possible through traditional connectors.

The other end of the ribbon that joins to the LCD is terminated on the glass on Indium tin oxide (ITO) which is one of the most widely used transparent conducting oxides.

If you want more information there are many different types of LCM assemby (LCD Display plus it driving chips) to look at but these are the main ones (increasing in density):

In manufacture of these modules a machine is used for assembly which would compress HSC to the LCD Or the PCB and then apply the correct amount of heat.

I am attempting to fix a TV with vertical lines in it. Actually it was showing a black screen. I cleaned the ribbon connections and now I get an image with some multicolored vertical lines. ( good progress) . When I looked at the ends of the cable some of them were "missing" the last 1 - 2 mm of gold plating? do you think the method you used of slicing the ribbon to even the pads up is a good method? Or is there a way of replating/tinning the missing portions?

These graphite ribbon cables appear to have a layer of clear tape on either side of the graphite paths. To expose a new area of graphite paths for reconnection should the original path be damaged, the tape on one side needs to be peeled back. In my case, when I attempted to peel back the tape some of the paths fragmented and went with the peeled back tape. I suspect that in the case at hand, the peel back was not necessary and heat was used to reattach the previously exposed paths.0

My flat ribbon seems to have a plastic covering on both sides but looks just like your pictures. Must I remove the plastic covering on the attachment side before applying heat to make the connection or does the plastic stay in place and somehow act as a glue when hot?0

Attached is a picture of a screen from a Brookstone clock. I think it may be an LCD. The black pads show where a ribbon cable was connected and I see not transmission paths from the pads into the screen. How does this work? Is it really an LCD?

Are the paths in this ribbon cable covered on both sides as mine is and can you adhere the ribbon without removing any covering by applying heat? And what do I do on the LCD side where there appears to be no pads on the LCD but the ribbon cable was apparently applied in this manner?0

I have two items to add, kapton tape and sil-pads used to isolate heat-sinks from semiconductor devices. With kapton tape it brings the means to secure the ribbon to the board, place the tape over the whole connection area, and kapton resists heat very well, ( try and melt it with your soldering iron). This means an average soldering iron turned down will allow heat to be applied to each joint. With experience a rework can be done in a few minutes. The bond can also be renewed on the LCD glass as well, kapton also works here. Sil-pads allow heat to be passed to the joint with some pressure applied at the same time. The sil-pad can be dragged up and down all the ribbon connections allowing uniform heating. Once the bond is resurrected the sil-pad is discarded. http://goo.gl/mpZNkm0

Sorry, the connector on the link doesn"t match the board design... you must search for FFC, FPC connectors with the number of vias of your cable and look for the real dimensions on the datasheet.

I just thought the same way, adding aLCD flat connector... then you can swap chinese or VDO oem screens. Seems the VDO LCD(as for Audi A3-Vw golf/jetta4) have 50 pins and the ribbons is 48mm width. Then you have to look to modify the metal bracket to avoid pressure on ribbon.

i would not rule out a connector fix totally but its nice if you can fix for zero cost if possible. Also you then have to manage the mechanical constraints as well as choosing a suitable connector. Usually only the semi flexi PCB circuits ribbons go into connectors not the carbon screen printed sort so may not be so desirable.0

i have an alarm clock which doesn"t have a ribbon, but instead some sort of rubbery contact strip against which the display should be pressed. You can find pics of it on google images for "lcd rubber contact strip", it seems to be called a zebra rubber. Any idea on how to glue/solder the display to that rubbery contact strip?More CommentsPost Comment

This 50-pin FPC SMT top-contact connector fits perfectly with our 2.8" TFT display with resistive touch screen. It is fine pitch so it is not so easy to solder! This is for expert SMT solderers.

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