When considering finishes, if the ultimate in reliability and surface
flatness are key considerations, you must give electroless nickel,
electroless palladium, immersion gold (ENEPIG) some consideration.
Regards,
Bob Metcalf
Western Regional Manager
Atotech USA Inc
1750 Overview Drive
Rock Hill, South Carolina 29730 USA
Mobile: 714-334-7667
e-mail: [log in to unmask]
Internet: www.atotech.com
Managing Director: Kuldip Johal
This e-mail and any attachments hereto are business documents of Atotech
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From: "Stadem, Richard D." <[log in to unmask]>
To: <[log in to unmask]>
Date: 06/02/2011 07:46 AM
Subject: Re: [TN] Best Board Finish - beyond gold
Sent by: TechNet <[log in to unmask]>
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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