Received: |
by ipc.org (Smail3.1.28.1 #2)
id m0wofVm-000BjaC; Wed, 16 Jul 97 20:37 CDT |
Old-Return-Path: |
|
Date: |
Wed, 16 Jul 97 21:48:20 EST |
Precedence: |
list |
Resent-From: |
|
Resent-Sender: |
|
X-Status: |
|
Status: |
O |
X-Mailing-List: |
|
From [log in to unmask] Mon Jul 21 11: |
50:15 1997 |
TO: |
|
Return-Path: |
<TechNet-request> |
Resent-Message-ID: |
<"vBH4f3.0.59A.bTNpp"@ipc> |
>From willli Wed Jul 16 20: |
37:56 1997 |
From: |
|
X-Loop: |
|
Cc: |
|
Subject: |
|
Message-Id: |
|
Parts/Attachments: |
|
|
Then again, the reduced oxide is supposed to be plain copper, isn't
it?
Matt Byrne
HADCO-Owego
______________________________ Reply Separator _________________________________
Subject: Re: Part II: Mechanism of Wedge Void Formation
Author: [log in to unmask] at SMTPLINK-HADCO
Date: 7/16/97 07:59 AM
Hi TechNet -
There is a tool available that can very accurately measure both the
type and the quantity of copper oxide present on a surface in a
nondestructive manner - Sequential Electrochemical Reduction Analysis
(SERA). The ANSIJ-STD-003 PWB solderability committee recently
completed a gauge R&R study on several SERA equipments and is in the
process of submitting the test method for inclusion in the IPC-TM-650
specification. Although the 003 committee's focus is on solderability,
the SERA test method can also evaluate copper surface oxides. Contact
the folks at ECI Technologies (201-773-8686) for more information. Use
of this method could be used to eliminate the subjectiveness or as a
supplement to copper oxide identification by visual appearance.
Dave Hillman
Rockwell Collins
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: Part II: Mechanism of Wedge Void Formation
Author: [log in to unmask] at ccmgw1
Date: 7/15/97 5:14 PM
Rudy Sedlak mentions that a reduction in oxide thickness from black to
brown to red in color assists in deterring wedge voids.
This trend could lead to a cosmetic difficulty. Am I correct?
Matt Byrne states that reduced oxide helps: Here I take this to be
reduction from cupric to cuprous ions which Rudy Sedlak confirms.
Richard Fudalewski states that reduced oxide brings in a problem of its
own, but I am uncertain which definition that Sedlak mentioned he is
referring.
****
New question: At what minimal thickness does one entertain cupric ion
post oxide reduction with DMAB? What are the trade offs cosmetically
versus functionality (w.r.t. wv's)?
Again thanks,
Josep
P.S. In direct answer to Byrne's question of reduction problem, we see
wv problems intermittently. The goal is to strive for a cosmetic black
coating. Thickness entering DMAB is typically 0.28mg/cm2 (black not
brown before immersion). Acid resistance (10% HCl) is greater than 2
hours.
These wv issues are not related to layer counts. I cannot as yet pin
the mechanism down but have not ruled out materials such as prepreg.
I'd like to understand more about the contact mechanism of prepreg
during lamination, whether other's verify Tg of lots, and if this has
ever been an issue in wv troubleshooting.
[log in to unmask]
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************
***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]> *
* with <subject: subscribe/unsubscribe> and no text in the body. *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] *
***************************************************************************
|
|
|