By Bob Wettermann
There are several instances where the small quantity of BGAs needs to be Reballed. These include but are not limited to cases where a single device needs to removed from the PCB and the same device needs to be reballed and be placed back down on to the board. This may be in cases where there is contamination on the board or on the solder balls. Another use for a single preform is in cases where the repair technician has available a brand new device but it is of the incorrect solder alloy. In these cases the replacement BGA needed to have the ball removed with the solder preform being used to re-attach the solder balls using a reballing solder preform.
There are several instances where the small quantity of BGAs needs to be Reballed. These include but are not limited to cases where a single device needs to removed from the PCB and the same device needs to be reballed and be placed back down on to the board. This may be in cases where there is contamination on the board or on the solder balls. Another use for a single preform is in cases where the repair technician has available a brand new device but it is of the incorrect solder alloy. In these cases the replacement BGA needed to have the ball removed with the solder preform being used to re-attach the solder balls using a reballing solder preform.
The steps for replacing the balls on a single BGA include the following:
- Deball or remove all of the balls from the BGA. The easiest way to do this at the bench is to use solder braid, paste flux and a blade tip of the proper temperature to remove the solder balls. Apply the proper paste flux knowing the alloy you are desoldering and the type of chemistry (no clean or water soluble) that is preferred by the end user. Using the solder braid and slowly moving the blade tip up and down, deball the device.
- Clean the bottom side of these prepared pads using the proper cleaning solution. Isopropyl 97% pure or greater is usually sufficient for this task.
- Inspect the cleaned and prepped BGA pads looking for damaged pads or laminate. Insure that the pads are relatively flat so the replacement solder balls can easily land on the pads.
- Please the proper plastic/tape reballing preform on flat surface and place the device (with flux paste smear down to the pads) on the top aligning it properly
- Send the device through reflow source using the proper profile
- When still warm pull of the preform , clean and inspect