BGA REBALLING SERVICES INFORMATION
September 1, 1998
SIX SIGMA has been processing BGA reballing (and initial attach) lots since shortly
after our parent company, Winslow Automation, acquired the SolderQuik TM
line of products from Raychem Corporation in February 1996. We have processed hundreds
of lots, ranging in size from 1 component to thousands of components. The SolderQuik
TM BGA Preform consists of an array of solder spheres held in a water dispersible
paper/polymer carrier. These preforms provide a simple, extremely flexible, repeatable
process, which requires very little operator skill.
Process Flow of SIX SIGMA BGA Reballing Lots
Reballing lots first receive an incoming QA inspection for catastrophic defects,
such as damaged or missing pads, exposed or damaged metallization, and substrate
cracks. The parts are then sent through an aqueous batch cleaning process, designed
to remove flux residues left on the part during board placement and removal. After
cleaning, the components are sent through a moisture removing bake of 125oC
for eight hours, and then dry packaged to prevent "popcorn" cracking and delamination
The next step is to remove the residual solder from the components which is typically
left from the board removal process. For lots containing only a few components,
we use solder wick and a temperature controlled soldering iron. For lots with larger
numbers of components, we remove residual solder using the Flexline«
Robotic Wave Solder System. Both "deballing" processes are followed by another clean
***Improper procedure for removal of residual solder can cause irreparable
damage making the pads unsolderable. Customer should never remove residual solder
before sending parts to SIX SIGMA for reballing.***
New solder sphere arrays are then attached using SolderQuik TM BGA
Preforms on an inline Heller convection oven.
After ball attach, the parts undergo a thorough post clean process. In-house
ionograph testing is done on random lots to insure that cleaning is sufficient.
A final QA inspection follows the completion of the reballing process, to insure
that the components meet our high standards of workmanship.
The final step, is to dry pack and seal the components before shipping back to
the customer. We strongly recommend that the customer perform a moisture removing
bake before putting the parts through another reflow cycle. Upon customer request,
we will perform this outgoing bake for no extra charge.
CBGA'S and High Lead (90Pb/10Sn) Solder Ball Attach
SIX SIGMA has also perfected a flexible process for the attach of high lead solder
spheres which is considerably more complicated than the process for eutectic solder
ball attach. We provide excellent control over eutectic solder volume, and high
lead ball alignment.