Your analysis is very close, but there are more concerns than just

drilling. There are several root causes evident in this report. First, yes

the drilling appears to be rather aggressive as evidenced by several areas

of "drill ripout" and copper wicking. This condition then appears to be

exaggerated by a slightly too aggressive hole clean that made the hole wall

even rougher. The brightener level of the copper plating bath then was not

correct. and the bath was unable to cover the glass bundles without

creating copper folds in the first plating process. The second plating

process then could not adequately cover these folds adequately (see photo

D1, top left). These plating folds are opening up causing your intermittent

opens, which after time will become permanent opens as thermal cycling

extends them around the circumference of the via. From my experience the

ranking of root causes is :

   Brightener level in the copper plating bath

   Drilling parameters

   Hole clean process

   This may even go back as far as the cure of the laminate material



The "cobblestone plating" is not rejectable by itself, but should lead to a

review for copper folds that have not been adequately covered with the

minimum amount of copper plating. This condition is a process indicator of

underlying concerns, and may or may not indicate failures.



Tom Kemp

Rockwell Collins

Collins Printed Circuits

Quality Manager





                                                                           

             "Constantino J.                                               

             Gonzalez"                                                     

             <[log in to unmask]                                          To 

             T>                        [log in to unmask]                

             Sent by:                                                   cc 

             IPC-600-6012                                                  

             <IPC-600-6012@ipc                                     Subject 

             .org>                     [IPC-600-6012] Cobblestone"         

                                       appearance on via wall.             

                                                                           

             08/05/2005 08:54                                              

             AM                                                            

                                                                           

                                                                           

             Please respond to                                             

             "(Combined Forum                                              

               of D-33a and                                                

                   7-31a                                                   

              Subcommittees)"                                              

             <IPC-600-6012@IPC                                             

                   .ORG>                                                   

                                                                           

                                                                           









Hello here is Constantino J. Gonzalez from ACME, Inc. – Chairman of

IPC-A-610 Committee and one of my customers had a question.

Need your assistance on below ...



boards are failing for boot up / intermittent boot up with certain fallout

rate and Burn-in failures.



Affected location : U6 & U3 ( BGA) sent 2 board to 3rd party lab for a

failure analysis. ( report as attached)



-As you can see  the solder joints looks  good.

-There was no evidence of black pad .

- Double plating on via hole with "cobblestone" appearance on the 1st

plating.

-CU Wicking



I wondering why the hole wall structure has "Cobblestone" appearance?

Is this acceptable ??

We are unable to perform plating analysis as we don't have any more raw

cards.

Can Cu wicking, lead to boot up failure??

Is there any other analysis that can be perform ??



What is your opinion ??

Appreciate your help.







ACME F







Regards from your,



Official IPC MASTER INSTRUCTOR







Constantino J. González



President / Consultant Engineer



IPC-A-610 Committee Chairman







ACME, Inc.



AMERICAN-HISPANIC COMPANY



513 CLEVELAND STREET



RAPID CITY, SOUTH DAKOTA 57701



USA



E-mail: [log in to unmask]



Phone: 605-381-5963



Fax:    605-341-4261







(See attached file: Cobblestone.doc)(Embedded image moved to file:

pic07278.gif)