For Release
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 during processing.

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 cycle.

***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.

Chad Hyatt
Process Engineer