FPC Replacement Didn’t Resolve My Issue

Updated 6-25-2016 by Joe K @ iMicroTek

One of the biggest misconceptions of cellphone / tablet FPC connector replacement is the general assumption of what “could” be wrong when a cellphone or ipad screen does not work or does not have “touchscreen” function. Many times the assumption is: “if it’s not the screen itself it MUST be the connector”.

While the above conclusion may be true in some cases,  it’s not true in ALL cases. Once in a while we’ll hear back from a customer after a connector replacement stating that the logic board still does not show any video or the touch function still does not work.

Here is another scenario, lets take for example an iphone 5 front camera FPC connector is damaged. The user assumes that’s the only problem with it as he / she can see that the connector is clearly damaged and wants it replaced. If the damaged connector’s pins are making contact with each other (in essence shorting) and power (via the battery) is still applied, there is always a small chance that additional damage is now present to the controller IC or supporting components at this point. The user buys a connector replacement service, and we replace the FPC connector. They receive the logic board back and the front camera still does not work. The user is thinking there must be a problem with the new FPC connector because what else could it be? In all actuality it could be quite a few things as described in this article.

First, our FPC connector / cable replacement service should ONLY be purchased after you have visually verified that the original FPC connector is indeed damaged. Our service should not be purchase if you are assuming the problem is FPC connector related and your connector is in good condition.  Of course you can go forward with an FPC Connector replacement to be absolutely certain and rule out the possibility of the problem being connector related as long as you accept the fact that the problem may not be resolved.

What many people and “techs” don’t understand is the complexity of the motherboard / logic board design. There is more to a motherboards ability to display an image on the screen than most people realize. Each and every function of a cell phone / ipad / tablet is controlled by it’s own controller IC and sub-circuits. Those sub-circuits often intersect with the main processor in most cases. The display and the FPC connector are the LAST components in a long list of the circuit’s structure.

Also, within a device’s circuit (when I say device I mean a particular function within a cell phone)  architecture, there are also support IC’s which consist of resistors, capacitors, diodes.. etc etc.. if ANY one of these items is missing or damaged it will also affect the function of that particular device.

How do these IC controllers and supporting components become damaged? Well, there are many ways that they can become damaged. Listed below are the most common:

  1. Liquid exposure is one. Water / liquid spill / exposure is the single most damaging thing that can happen to a motherboard.
  2. Also, mis-handing can cause IC’s / chips to be broken off the board.
  3. Another thing that many people don’t realize is this, when an FPC connector is damaged, in many cases the tiny pins of the connector end up making contact with each other and effectively creating a short condition as there is usually still power applied to the board (via the connected battery). This condition can and will damage support components within the device’s circuit and possibly damage the IC controller for that device.
  4. Also, simple component failure on it’s own without any outside influence may also happen and is very common.
  5. This is important, this is the single most common reason the motherboard does not work after a connector replacement. Many times, a user will contact me saying: “something must have went wrong with the FPC replacement because it used to work (other aspects of the board) before I sent it in, now it won’t turn on (or whatever the new symptom the board is showing) Yes, that’s correct, the board probably DID behave differently, but it didn’t START behaving differently because it was here for a connector replacement, it started behaving differently AFTER you removed it from the case / base. MOST of the damage occurs when the user is trying to remove the motherboard / logic board from the case / base.What you have to understand is this: Once you take it upon yourself to try and repair a mobile device or tablet YOU become the repair technician. You must take all precautions not to damage the motherboard in any way. We are merely here to offer a specific service to technicians that don’t have the ability to precisely micro solder these difficultly tiny FPC connectors / cables. I have another article listed above that mentions how to be careful when working with these tiny connectors.

Unfortunately, there is only one way to determine if any additional IC / chip damage is present on the board and that is by replacing the FPC connector and attaching the device that the connector is for (assuming the connector was damaged in the first place) But unfortunately, if the problem still persists, it’s beyond the scope of our service offerings.

Our FPC connector replacement process consists of validating the proper solder bond of each pin to it’s corresponding motherboard pad twice, once during the replacement and a second time after the completion of the replacement process. After replacement of the FPC connector, the customer can rule out the possibility of the problem being related to the connector. 

In most cases, when an FPC connector is damaged, replacing the connector usually resolves the issue and all is well. But in some cases the problem is still present due to additional damage somewhere else on the board. Also, there are cases where the screen (or whatever device the connector is for) that the customer is trying to use is indeed damaged or defective and needs to be replaced.

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