Although we mainly do instrument cluster repairs, we decided to help our friend and repair his broken in road accident key. Dealer wanted hundreds £ and required him to bring the car to their workshop which is impossible at the moment. It’s 2016 Mercedes Benz GLE, so called BGA key, FBS4.
The key was cracked. Repairing broken tracks didn’t help as it’s a multi layer PCB.
Car owner provided us with identical key bought from Chinese seller.
This one was extremely bad quality, poor soldering, not all components were soldered in but that’s not a big deal, we can easily fix it. The plan was to swap the chip containing the coding. It’s a BGA chip 5x5mm with 48 pads. We tried to find a decent stencil for it but we couldn’t so we aligned all 48 balls by hand. The balls are 0.4mm in diameter, so not that small.
Everything went well and the key works now.
List of ICs used in the key:
|5×5 mm||QFN 16|
|5×5 mm||QFN 32|
|5×5 mm||QFN 28|