Comments

1. The idea Hole would be smoother but these are acceptable.

2. The "cobblestone" effect is normal grain/etching variation. Two layers of
plating is also normal.

3. There was no evidence of cracks.

4. I don't think the wicking is the problem...  Excessive Wicking tends to
cause shorts (not opens)or high resistance shorts overtime not soon after
fabrication.

Summary, I think the holes are ok.

I agree with the report, unless the electrical problem can be isolated to a
board via more microsections would find the same.

Possible Actions:   Under the theory that the via holes are marginal: I
would take some part of a board and float (10 seconds @550F) the vias 3x and
5x and section.  If these don't crack, the boards are fine.  If some do, I
would keep looking at the board as potential problem.


Mike Hill

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]]On Behalf Of Constantino
J. Gonzalez
Sent: Friday, August 05, 2005 9:55 AM
To: [log in to unmask]
Subject: [IPC-600-6012] Cobblestone" appearance on via wall.


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