Double-sided BGA design considerations

FPC double-sided layout BGA, already in some products, but due to the complexity of the production process and maintainability considerations, we must refer to the following comments:

• Do not overlap the double-sided BGA and reserve a certain distance, because if the BGA of a certain side is bad, it will be very difficult to repair and it is very likely to be scrapped.

• In order to prevent the BGA solder joint on the bottom side from being melted under secondary reflow, false soldering and foaming occur, so the temperature of the bottom side must be lowered during the second reflow. It is best reduce the temperature of the bottom side to lower than the melting temperature of the solder joint, to ensure the solder joint does not melt again, or fixed the bottom BGA using a fixture.

  
  

There are the following ways to prevent the PCB board deformation:

1. Place metal frame what have support force around the BGA to strengthen its ability to withstand stress.

2. Gluing around the BGA or gluing the back of its corresponding PCB board to strengthen its ability to withstand stress.

3. If our purpose is only to protect the BGA, then we can mandatory fixed the components near the BGA, this way can protect BGA and the components near the BGA not easy to deform. Fox example, add screws or fixed fixtures around the BGA.

4. Strengthen the strength of the shell to prevent its deformation from affecting the internal PCB board.