If you want to build cool things these days, you’ve probably had to master surface mount electronics. However, for many people, ball grid array (BGA) is still intimidating. Have a look at [VoltLog’s] video about his techniques for soldering BGA and inspecting that you managed to do it right.
He’s got quite a few tips about things like surface finish and flux selection. It looks easy when he does it. Of course, having a good PCB with good registration markings will help too.
You can’t get a soldering iron under the part, of course. A hot plate provides heat from underneath. A gentle push from a hot air gun will push the solder balls over the melting edge. Even taking the part off the hotplate requires a special technique.
Without seeing the result, how can you know if it was successful? Pros can use an X-ray machine, but you probably don’t have one of those sitting in your shop. [VoltLog] uses a DVM and tests the internal protection diodes that the chip almost certainly has on its pins. However, to do that, you need to put the chip on a bare board. If you were repairing an existing board, the technique wouldn’t be useful since other components on the board would throw the measurements off.