Did you buy it in Washington, making it Wally's Walla Walla Wallet?
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
Sent: Friday, August 18, 2006 6:17 AM
To: [log in to unmask]
Subject: Re: [TN] LEADFREE BGA ISSUE
Dave as usual is correct. Wally's 1969 information is extremely useful.
I keep a 2" square laminated copy of a portion of Wally's data in my
wallet:
Element Dissolution Rate (u"/sec.)
Gold (Au) 117.9
Silver (Ag) 43.6
Copper (Cu) 4.1
Palladium (Pd) 1.4
Nickel (Ni) 0.05
Platinum (Pt) 0.01
Regards,
George
George M. Wenger
Reliability / FMA Engineer
Base Station and Subsystems Group
Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, August 18, 2006 8:48 AM
To: [log in to unmask]
Subject: Re: [TN] LEADFREE BGA ISSUE
Hi folks - one reference that was published by Bader in 1969 but is
still very useful today concerning dissolution rates of metals in solder
is this
paper:
W. Bader, "Dissolution of Au, Ag, Pd, Pt, Cu, and Ni in a Molten
Tin/Lead Solder", Welding Journal 48, pp. 551s - 557s
A "classic" data set that many, many investigators still reference.
Dave Hillman
Rockwell Collins
[log in to unmask]
"Stadem, Richard
D."
<Richard.Stadem@G
To
D-AIS.COM> [log in to unmask]
Sent by: TechNet
cc
<[log in to unmask]>
Subject
Re: [TN] LEADFREE BGA ISSUE
08/18/2006 07:23
AM
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
"Stadem, Richard
D."
<Richard.Stadem@G
D-AIS.COM>
Amol,
Sorry about any confusion I caused, what I meant was that
Klein-Wassink's charts describe the rate of dissolution of nickel into
molten pure tin, not a tin alloy.
-----Original Message-----
From: Kane, Amol (349) [mailto:[log in to unmask]]
Sent: Friday, August 18, 2006 6:50 AM
To: TechNet E-Mail Forum; Stadem, Richard D.
Subject: RE: [TN] LEADFREE BGA ISSUE
Hi Richard,
Not to split hair, but I am a little confused with your statement "the
information on the dissolution rate of nickel into a tin alloy from
Klein-Wassink's charts are based on pure tin, not a tin/lead alloy", but
how can tin be pure if it is in a alloy form with some other metal??
Am I missing something here?
Regards,
Amol Kane
M.S (Industrial Eng.)
Process Engineer
Harvard Custom Manufacturing, Inc.
941 Route 38 Owego, NY 13827
Phone: (607) 687-7669 x349
[log in to unmask]
www.harvardgrp.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard
D.
Sent: Thursday, August 17, 2006 1:56 PM
To: [log in to unmask]
Subject: Re: [TN] LEADFREE BGA ISSUE
Don't always assume that just because the finish was ENIG, that it was
the root cause. It may have contributed to it, but usually there is no
one root cause when this happens.
Secondly, even when good wetting does take place on ENIG-finished pads,
upon removal the pads often appear dull. This is just the nature of the
nickel finish. It does not always indicate a solderability problem with
the finish.
The problem may have been a reflow profile that was not hot enough, with
TALT being insufficient to form a good IMF to the nickel base. It is
slightly more difficult to achieve this with standard 63/37 solder on
nickel than on copper, and appears to be even more difficult with SAC
alloy on nickel than on copper. While the temperature is significantly
hotter, the SAC alloy does not seem to form a good IMF with nickel as
readily as the 63/37 solder does.
Werner, the information on the dissolution rate of nickel into a tin
alloy from Klein-Wassink's charts are based on pure tin, not a tin/lead
alloy. What is the effect on nickel's dissolution rate when the amount
of lead in the solder alloy is varied, say from 37% to 0%?
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Colin McVean
Sent: Thursday, August 17, 2006 9:34 AM
To: [log in to unmask]
Subject: Re: [TN] LEADFREE BGA ISSUE
<Certain pads were very dull and when solder is applied on it, it seened
there was dewetting issue>
Sounds like an issue with the solderability of the ENIG rather than the
substrate. Check with your PCB fab supplier for their comments.
<By the way, such kind of issue happened only to one customer...>
It only takes one instance of poor process control on ENIG to see faults
occurring. Looks like this is what has happened in this case.
Rgds
Colin
Colin McVean M.Inst.C.T.
Production Manager
Artetch Circuits Limited
Main: 01903 725365
DD: 01903 712926
Email: [log in to unmask]
www.artetch.co.uk
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Poh Kong Hui
Sent: 17 August 2006 15:24
To: [log in to unmask]
Subject: Re: [TN] LEADFREE BGA ISSUE
Hi Technetters,
Could someone advise me the reasons to following issue.
1. There are total 25 boards for the evaluation purpose.
2. Round 1, we assemble d11 units SAC BGA onto board of ENIG. The
result
was 10 passed functioonal, 1 piece was not working. There was no signal
& power to the BGA unit.
3. Round 2, 4 boards were being assembled, 3 passed, 1 was not
working
4. Round 3, 10 boards were biring assembled, 1 was working, 9 not
working.
The above-stated boards undergo the same temperature profile.
At the beginning, we were suspecting the board of ENIG. When 1 BGA was
being removed from the failed board, and intend to perform the
reballing, we realise the not all BGA substrate pads were able to
solder. Certain pads were very dull and when solder is applied on it, it
seened there was dewetting issue.
My question is, if the failure of the BGA that was due to BGA's
substrate or otherwise.
By the way, such kind of issue happened only to one customer...
Thanks
KH Poh
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