Lead-Free BGA Rework

There are a lot of variables in BGA rework in general, and the switch to lead free has only magnified some of the sore spots.

Perhaps with a little bit more information someone here can be of help.

What is the size and thickness of the PCB? What is the size and style of the BGA compoent in question? What type of rework equipment do you have at your disposal?

You should never have an issue with pads being removed during the removal process. When you are prepping the site is typically when pad damage occurs. If your machine is lifting the component too soon and tearing pads off, then you have a machine problem. If you are not using a machine, and are using some kind of hand held heating device then you have other problems not addressable here.

As far as warping of the BGA, consider that your heating process is too quick. If you ramp to temperature slowly enough the package will have ample time to heat evenly, and help to avoid warp. It is not neccessarily a matter of a larger nozzle or a higher temp. Bottom side heating is CRITICAL to pb Free rework. Generally speaking, you cannot drive enough heat through the top of a BGA package to create good solder joints at the board level. It is so very important that the PCB substrate is up to temp as well. Otherwise you get collapsed spheres and poor connections.

I can see this going towards a discussion of IR vs convective rework machines.
IR = Good for Bottom heating, not so good for Component heating.
Forced Air convection = Good for bottom heating, Good for component reflow. (Thats why they build PCBs that way)

If at all possible try to have as much of the PCB heated evenly for the process. Try to keep the PCB at around 140 to 160C while your topside temps (depending upon the rework machine) may go from 270 to 290C

Good Luck. Lots of knowledge in this group, I'm sure between all of us we can get you on a better path.

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