TECHNET Archives

July 2009

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Werner Engelmaier /* <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Mon, 27 Jul 2009 13:23:51 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (171 lines)
 Hi Gaby,
You may be interested in my White Paper on how to specify PCBs for Pb-free soldering.
Werner


 


 

-----Original Message-----
From: Gabriela <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, Jul 27, 2009 1:56 pm
Subject: Re: [TN] OOPS! The copper is gone!










Right.
Scrolled the internet for a couple of days, much on copper dissolution
there.
Another present from ROHS.
Luckily we had no delamination because we used high Tg board material, but
also luckily we have no BGA's on it, because my latest information is that
High TG board material is bad for pad cratering. (another present from
ROHS).
I wonder how many cross sections I will have to do in order to validate the
process.
Gaby

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Monday, July 27, 2009 7:39 PM
To: [log in to unmask]
Subject: Re: [TN] OOPS! The copper is gone!

Hi Gaby - you found the unhappy recipe for lead-free soldering: thick
pwbs, lots of thru hole connectors and heavy internal copper layers =
danger of copper dissolution. Both the IPC APEX and SMTAI International
Conference proceedings for the last 2 years have some excellent papers on
the topic of copper dissolution which may be helpful for your issue. You
may need to investigate using a different solder alloy instead of SAC305
(?) to control the amount of copper dissolution. Good luck.

Dave Hillman
Rockwell Collins
[log in to unmask]



Gabriela <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
07/27/2009 11:56 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Gabriela <[log in to unmask]>


To
[log in to unmask]
cc

Subject
[TN] OOPS! The copper is gone!






No surprise at all.
Assembly went through lead free SAC selective soldering. Thick, 20
internal
layers motherboard. Immersion silver plated.
Lots of connectors (not only), populated on both sides. Conventional 25um
copper in holes, outer layers over 1/2 oz copper.

Was soldered before with Sn/Pb.

No free meals, haha.

Want to redesign to ENIG - seems to be the only choice.

I wonder if there is a thumb rule for selecting the possibility of
selective
soldering according to design and platings.

Also, if ENIG is safe for this process, even if rework with SAC ot Sn100
for
hole fill and shorts must be performed.

We will try to overcome the problem, in the meantime by using Nihon
superior, but in order to get good hole fill for such a thick board, the
parameters will be too harsh , I suppose.
Cross sections look very beautiful- pads are gone, knee is gone, barrel is
playing hide and seek, inner layers just end to nowhere.
How did you wise people validate this process and never mentioned anything
on the NET?



Gaby




---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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
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 15.0
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
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 15.0
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
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 15.0
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
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
-----------------------------------------------------

ATOM RSS1 RSS2