Hi Richard! The gold acts as an "environmental barrier" to the prevent the
Pd from collecting things from the use environment. Pd is a real cool
element - it has properties which allow some pretty nice physics (Pd is
used to seed plated thru holes for plating). A thin flash of gold over the
Pd dramatically increases long term solderability and wettability. Texas
Instruments has been putting a flash of gold on their classic Pd/Ni
component finish for several years now as a surface finish improvement.
Rockwell Collins did some testing of Au/Pd/Ni and Au/Pd/Cu pwb finishes in
the late 90's - we had great success in the testing portion of the program
but the expense/availability of the finish are big disadvantages. Au/Pd/Ni
has been called the "universal" finish as it can be both a wirebondable and
solderable surface finish. You can also get Pd embrittlement of solder
joints in a similar fashion to Au embrittlement - the embrittlement is
another issue that some folks don't want to deal with so the finish is
avoided. Good control of the Pd thickness and your soldering process can
result in avoidance of Pd embrittlement issues.
Dave Hillman
Rockwell Collins
[log in to unmask]
"Stadem, Richard"
<Richard.Stadem@G
D-AIS.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
08/22/2005 03:18 Re: [TN] Black pad
PM
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
"Stadem, Richard"
<Richard.Stadem@G
D-AIS.COM>
If Pd is used over the nickel, then why does one need the gold? The gold
is put on to preserve the solderability of the nickel. Does not the
palladium do the same thing? I know we would not solder to the
palladium.
From my bad experiences in the past with palladium applied as a final
termination finish to leaded SMT components, I would not want to solder
with palladium in the mix if I can help it.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
Sent: Monday, August 22, 2005 3:09 PM
To: [log in to unmask]
Subject: Re: [TN] Black pad
Jason,
I don't type as fast as I think. I meant to say "without any reference
to" not "with any reference to".
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 Wenger, George M.
Sent: Monday, August 22, 2005 4:07 PM
To: [log in to unmask]
Subject: Re: [TN] Black pad
Jason,
Let me try to answer your question with any reference to "Black Pad". I
don't like to use an appearance name to describe a failure mode. The
short answer to the question can a brittle interface fracture be present
if using NiPdAu is YES.
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 Jason Gregory
Sent: Monday, August 22, 2005 3:44 PM
To: [log in to unmask]
Subject: [TN] Black pad
Hello all,
after a short hiatus, I'm back.
I have a question - Can the Black Pad Defect be present if using NiPdAu?
Can the palladium prevent black pad?
Jason Gregory
Manufacturing Engineer
Innova Electronics
(281)653-5593
(281)653-5594 fax
(281)212-0844 cell
[log in to unmask]
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