Hi,

Is this poristy test, something that can be used to check immerision Au/Ni 
or is it only good for Electroplated Au/Ni?  Also,  how porous can immersion 
gold be( 1%,2% -10%)  to allow for good solderabilty characteristics using 
no-clean flux for SMT reflow and  wave soldering?

Scott
 ----------
From: TechNet-request
To: [log in to unmask]
Cc: 'GM'; John Kelleher
Subject: FW: ASSY:Au/Ni Coated Boards
Date: Thursday, May 29, 1997 10:04AM

Zoran,

Two things about Au over Ni to note. First of all, over time, Ni will
diffuse thru gold (mostly along the grain boundaries) and get onto the
surface where it will oxidize. Enough Nickel oxide on the surface can
give you solderability problems.  A strong flux may help. The time it
takes for this to happen depends on the thickness of the gold.  I
don't have any numbers but 6 months does not seem like a very long
time.

Secondly, the quality of the gold plating is just as important. If the
gold has a lot of porosity, Cu and Ni can diffuse to the surface. Try
a Nitric acid vapor test (gold porosity test) to ensure that porosity
is not a problem.  Hope this helps. Perhaps others can give you some
advice on what, if any, flux would work.

Regards,
Paul Terranova


Phone: 508-467-3109
FAX: 508-467-6796


DIGITAL's Analytical and Environmental Test Services Lab
Digital Equipment Corporation
M/S: MRO1-3/D2
200 Forest Street
Marlboro, MA  01752


 -----Original Message-----
From:   "MRMTS::MRMTS::MRGATE::\"DASMTS::PMDF::ipc.org::TechNet-request\"
"@sandz.mro.dec.com
[SMTP:"MRMTS::MRMTS::MRGATE::\"DASMTS::PMDF::ipc.org::TechNet-request\"
"@sandz.mro.dec.com]
Sent:   Wednesday, May 28, 1997 11:45 PM
To:     Paul Terranova
Subject:        ASSY:Au/Ni Coated Boards
From:   NAME: Raich, Zoran <[log in to unmask]@PMDF@INTERNET>
To:     NAME: [log in to unmask] <[log in to unmask]@PMDF@INTERNET>


Dear Technetters
We have some printed circuit boards with gold over nickel coating
which   are experiencing solderability problems, ie very poor wetting.
I have   heard that this may be due to nickel migration through the
gold over   time. The boards are approximately 6 Months old. Is there
a particular   shelf life for this type of coating before we need to
dump the boards?.
Regards
Zoran Raich
Process Engineer
NetComm (Aus) Ltd
(+612) 9878 7394
[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]      *
***************************************************************************