I'm surprised that no one mentioned the new board finish using nano-technology.
It is flat for fine pitch and solders better than any other Lead-Free finish out there without the issues of OSP and tin.
Research was done via the Lead-free Consortium in partnership with U-Mass Lowell, TURI.
TURI (Toxic Use Reduction -??, is partially funded by the EPA and the work and parts are supplied by the major Electronic companies in the Mass/NH area from board fab to design, contract Assemblers and companies offering test services like HALT testing and U-Mass Lowell providing the facilitator, assisting in the DOEs, generating all the analysis and plots from the inspection reports Benchmark Electronics provided and supported by Sam Shina a professor and well known author for Analysis in the electronics area. Robert Farrel, Benchmark Electronics is the principal Engineer leading the work along with Debra Fragoza of EMC
Anyone interested can Morose, Greg" < [log in to unmask] >; The U-Mass Lowell Facilitator/PHD and now Doctorate for the project. A complete list of the contributors and the new members developing nano-technology for component leads, planned for the future was presented.
John Goulet
MFG/Process Engineer
(Former member and contributor to the consortium for about 4 years).
----- Original Message -----
From: "David D. Hillman" <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, June 8, 2011 3:18:16 PM
Subject: Re: [TN] Best Board Finish - beyond gold
Hi George - I was on vacation whitewater kayaking in NC so I wasn't around
to contribute to the conversation. Great dialogue with everyone giving
very fair coverage to the all of the finishes and noting where they have
personal biases (and more importantly why the finishes do work for them).
Everyone has given Barbara the various options for the surface finishes
and she should be able to progress forward.
Dave Hillman
Rockwell Collins
[log in to unmask]
"Wenger, George M." <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
06/02/2011 10:56 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
"Wenger, George M." <[log in to unmask]>
To
<[log in to unmask]>
cc
Subject
Re: [TN] Best Board Finish - beyond gold
Barbara,
I've never met Richard but I've always agreed with his comments on TN. The
only thing I can add which I absolutely believe is that you need to do two
things; 1st is to listen to users of surface finishes like Richard and
Joyce) not suppliers of surface finished PCBs or suppliers of surface
finish chemistries because the users will tell you what works for them and
the suppliers will tell you what they need to for you to buy their
products and 2nd you should run trials before you switching.
HASL (i.e., SnPb HASL not Pb-Free HASL) is a great choice if you don't
need to be RoHS 6/6 compliant and you don't have fine pitch assembly
OSP and ImAg are good choices for fine pitch assembly.
From my participation many years ago on NCMS PCB Surface Finish program I
have bias against Pd surface finishes.
From my participation many years ago on NCMS Pb-Free program I have bias
against ImSn.
I'm a little surprised that no one has come forth to recommend switching
to ImSn or to stay with ENIG.
I'm also a little surprised you haven't gotten Doug's "it depends" comment
yet.
I'm also a little surprised you haven't gotten Dave's comment about using
all surface finishes and they work.
I do think that Richard, Frank and I have a bias toward ImAg because it
works well for our products and I think if you spoke to others who use
multiple surface finishes they will also indicate ImAg works well.
Regards,
George
George M. Wenger
Senior Principal Reliability / FMA Engineer
Andrew Corporation - Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Thursday, June 02, 2011 10:46 AM
To: [log in to unmask]
Subject: Re: [TN] Best Board Finish - beyond gold
I agree with everything you say, Barbara. It sounds like you are now on
your way to making the correct choice.
Stay away from immersion tin.
If you choose immersion silver, refer to both IPC 1601 and IPC 4553 for
storage and handling considerations. They can be managed.
The double-sided process can leave a slight reduction of solderability
with immersion silver PWBs by the time you are ready to hand solder any
PTH parts, making that more difficult to do, sometimes.
That is why I asked.
Also, if you select Immersion Silver, make sure that your PWB fabricator
has a good plating product, a well controlled process and some experience
with it.
Ditto with ENIG. Especially with ENIG.
Regarding immersion silver, it is susceptible to environments that are
heavy in sulfides, such as automotive exhaust, rubber processing, or paper
processing. Keep some of these things in mind both from an end-use
environment standpoint and from a storage standpoint. Do not store in
areas where there are open containers of soaps, fluxes, etc., nearby.
From: Barbara Burcham [mailto:[log in to unmask]]
Sent: Thursday, June 02, 2011 9:22 AM
To: Stadem, Richard D.
Cc: TechNet E-Mail Forum
Subject: Re: [TN] Best Board Finish - beyond gold
Thanks everyone for you imput. What a great group of people!
Richard,
The application will be double sided, fine pitch array components, some
through hole components and going into a shock environment.
I will need to connect with the assemblers to check on flux and paste
compounds. Does this information help? You make an excellent point. Must
have the total picture. I do not know, yet, how long boards will sit on
the shelf before moving into assembly, either. I do know that shelf life
will also impact this decision.
I do not think that I want to use tin...that hairy growth stuff.
Barbara
On Thu, Jun 2, 2011 at 8:01 AM, Stadem, Richard D. <[log in to unmask]<
mailto:[log in to unmask]>> wrote:
Barbara,
What is the application, board type, component types, etc?
Immersion silver is my personal favorite, but that is completely
irrelevant.
You should choose a board finish dependent upon the application of the
CCA, whether it has fine-pitch array components, including CSPs, whether
it is double-sided with PTH parts or hand-soldered components, the
environment the CCA will be used in, the flux type to be used, the alloy
that is required, and several other factors that go into the decision.
Without complete knowledge of all these factors, it is hard for anyone to
answer that question. I can tell you that IAg beats ENIG in cost, but each
finish has strengths and weaknesses. Some definitely have more or less
than others.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf
Of Barbara Burcham
Sent: Wednesday, June 01, 2011 8:17 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: [TN] Best Board Finish - beyond gold
Hey Y'all,
I am looking for a reliable bare board finish that beats the cost of gold.
What experience is out there?
What would you recommend?
Thanks,
Barbara Burcham
pcb Trace Design
[log in to unmask]<mailto:[log in to unmask]>
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