If a dissolution rate depends on the quality, then a LOT OF books and manuscripts would have to be recycled!
Regards,
Vladimir
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (647) 495-8727
Cell: (416) 899-1882
www.sentec.ca
-----Original Message-----
From: "David D. Hillman" <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
Date: Tue, 12 Mar 2013 17:46:52
To: <[log in to unmask]>
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
<[log in to unmask]>
Subject: Re: [TN] IPC-7095C vs IPC-4556 ENEPIG for SnPb
Hi Joyce - sorry but the dissolution rate of Pd is a function of the
temperature and the solder alloy you are using - straight forward
metallurgy and not a quality characteristic. Most of the us are still
using the data that Wally Bader published back in the 1960's for
successfully setting process parameters for today. What you are
describing is a methodology for avoiding having Pd embrittlement issues. I
agree with you that keeping the Pd plating layer thin makes the soldering
process easier but if I know the Pd thickness then I can set my soldering
process time/temperatures accordingly to avoid having solder joint
integrity issues.
Dave
From: Joyce Koo <[log in to unmask]>
To: "[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>
Date: 03/12/2013 05:40 PM
Subject: Re: [TN] IPC-7095C vs IPC-4556 ENEPIG for SnPb
Dave, I disagree with the dissolution rate of Pd. It depends: the plating
quality make all the difference. The eutectic Pb-Sn solder is capable to
dissolve Pd rather rapidly and form plate like intermetallics that could
change fracture dynamic of the joints. Keep it thin (less than 1000 A) or
protected Pd with other metal layers in order to limited time to exposure
to the solder could be beneficial. No publication on my side, just 1st
hand experience way back in the dark age.
--------------------------
Sent using BlackBerry
----- Original Message -----
From: David D. Hillman [mailto:[log in to unmask]]
Sent: Tuesday, March 12, 2013 06:24 PM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] IPC-7095C vs IPC-4556 ENEPIG for SnPb
Hi Kevin - I disagree with that statement in the IPC-7095C and didn't
realize it was there (otherwise I would have turned in a comment during
the draft efforts). I'll make sure to bring the topic back up in the 7095
committee as we start our next set of standards revision activities.
Rockwell Collins has successfully used ENEPIG surface finishes in tin/lead
and lead-free soldering applications for several years. We are in the
process of running another test sequence with one of the DOE legs using
ENEPIG surface finish so I should have an additional data set I can
present to the 7095 committee for review in regards to the wording you
detailed. Pd has very slow diffusion/dissolution characteristics in a
soldering process so you need to make sure you accommodate those
metallurgical reactions.
But - overall- the IPC-7095C represents a huge amount of work by the
committee with tons of new information that should be very useful to the
industry.
Dave Hillman
Rockwell Collins
[log in to unmask]
From: "Glidden, Kevin" <[log in to unmask]>
To: <[log in to unmask]>
Date: 03/12/2013 04:35 PM
Subject: [TN] IPC-7095C vs IPC-4556 ENEPIG for SnPb
Sent by: TechNet <[log in to unmask]>
Finally taking a few minutes to glance through some of the new IPC
releases...
I see a statement within IPC-7095C, specifically section 5.3.3.3, that
states ENEPIG is best suited for Pb-Free soldering, and that studies have
shown ENEPIG does not produce very reliable tin/lead solder joints, due to
the inability of Pd to alloy with lead.
I don't see any such warnings or statements in IPC -4556. Or am I missing
them? If this is true, it seems like it would be a major consideration
and would/should be included or mentioned in IPC-4556 Section 1.4.7
"Limitations of ENEPIG".
But, I could have it all wrong. So far all I have done is glance through
these new specs....
Kevin Glidden
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