That's because Dave is on vacation kayaking in North Carolina and I am
buried beyond belief.
Doug Pauls
"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]>
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]<
mailto:[log in to unmask]>
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask]<mailto:[log in to unmask]
> with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]<mailto:[log in to unmask]>: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]<mailto:[log in to unmask]>: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask]<
mailto:[log in to unmask]> or 847-615-7100
ext.2815<tel:847-615-7100%20ext.2815>
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
