BGA Rework Process - BGA / LGA Part Placement

Once the proper solder paste volume has been applied to the pads and cleaned off properly, the device can be placed onto the PCB.

When the device is placed using a modern area array rework system, split prism optics can be used to assist in the proper placement of the device. Using a prism, optical images of both the solder balls on the device as well as the PCB pads are superimposed in a stereomicroscope field of view on a monitor. The two images can then be aligned by X, Y and rotational adjustments.

Placement accuracy criteria is the same as the initial placement at the time of initial assembly. The device should be placed with a force per the manufacturers' specifications such that the solder paste contacts 50% of the PCB pad and not be in contact with the vias. For test boards the placement accuracy can be confirmed using double-sided tape adhered to the PCB BGA site. The BGA can then be placed onto this site, firmly held in place and examined at an angle under a stereomicroscope for accuracy.

The BGA can be hand-placed when using the StencilQuik™ process for larger pitch sizes (1.00 and 1.27mm). Care must be taken in handling the parts at the edges while making sure the operator is properly grounded.