The topic has already been discussed to death and "voted-on" in the past
within this forum and the LF forum.
Let the players decide which finish they want. They can live or die by
their choices. And they eventually will.
Weighing in, I have been involved with assembly/soldering of literally
hundreds of thousands of immersion silver pwbs used in
telecommunications equipment, medical equipment, military (non-space)
equipment including torpedoes, cruise missiles, RLG units for avionics
use, flight control computers, etc, etc, for several years now, for
several different companies. I have yet to see a reliability issue
related to the McDermid IAg finish. I have not experienced Kirkendall
voiding, and hope I never do.
However, I have seen and directly experienced severe and very costly
reliability issues with ENIG (Black Pad and brittle interfacial
fracture, undetected until in the field), HASL (copper dewetting from
improperly applied HASL, undetected until attempting to solder), and ISn
(severe surface degradation leading to solderability problems). I have
seen this at OEMs and CEMs that I worked for over the years. I have used
IAg with Pb-free products, including high-volume cellphone manufacture,
and it worked very well in that application as well. It seemed to
provide better wetting than ENIG with SAC 305 paste.
My second choice would be ENEPIG. However I need to qualify this by
stating that I have only a year's experience with it, but it has been a
good experience so far. Of course, there are design and use issues that
decide what surface finish is best as well. I would not recommend anyone
jump up and run out the door to their board house screaming "Hold the
press, I want IAg", as the selection of the finish must be fully
considered and fully qualified.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord
Sent: Tuesday, September 26, 2006 2:45 PM
To: [log in to unmask]
Subject: Re: [TN] PCB Finish
IAg-ISn: 1-1 (half)
interesting game.
I'm on neither side, because we don't use much of either....
The IAg seems to be more aggressive and one ought to put money on them.
On the other side, ISn seems to have better coaching and more
experienced players.
I'll stay up for another hour this night to see the next half.
Inge
----- Original Message -----
From: "Franklin D Asbell" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 26, 2006 1:03 AM
Subject: Re: [TN] PCB Finish
>6 of one, 1/2 dozen of the other.
>
> You should consider many factors in regards to which is preferable,
> for example, shelf-life, handling, packaging, number of thermal cycles
> the product will see, surface features, size/pitch, etc.
>
> In my opinion, handling durability is better with immersion tin; shelf
> life is better with immersion tin, and solderability are equal when
> measuring the same feature types.
>
> This is comparing the Omikron with the Macdermid Sterling Silver, and,
> most important, both baths operating optimal.
>
> The Omikron bath is more difficult to maintain than the MacDermid SS
> but if I had to choose one over the other it would still be the
> Omikron. The thickness of the Omikron needs to be on the high side (30
> - 40 micro") in order to pass multiple thermal cycles, I've not seen
> silver pass as many with similar results as tin.
>
> Again, there are many factors you should consider, keep asking
> questions, talk to suppliers, customers, run DOE's, get your hands
> dirty and you will find what suits you best, this is just my opinion.
>
> Franklin
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of kwood716
> Sent: Monday, September 25, 2006 4:25 PM
> To: [log in to unmask]
> Subject: [TN] PCB Finish
>
> Hey all,
> Question...
> Is immersion silver a more reliable and all around better finish than
> white tin? I am looking into using it instead of the Omikron OA-8 we
> currently use and would like some input.
> Note: I can't use and nickel in the PCB, these boards are for MRI use
> and have to be completely non-magnetic.
> Thank you
> Ken
>
> _____
>
>
> Saturn PCB Design, Inc.
> Kenneth J. Wood CID
> 2737 Bishop Lane
> Deltona, Fl 32725
> Phone: 407-340-2668
> email: <mailto:[log in to unmask]> [log in to unmask]
> www.saturnpcb.com <http://www.saturnpcb.com/>
>
>
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 Please
> visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> for additional information, or contact Keach Sasamori at
> [log in to unmask] or 847-615-7100
> ext.2815
> -----------------------------------------------------
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 Please visit IPC web site
> http://www.ipc.org/contentpage.asp?Pageid=4.3.16
> for additional information, or contact Keach Sasamori at
> [log in to unmask] or 847-615-7100 ext.2815
> -----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
