TECHNET Archives

June 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:
Mike Fenner <[log in to unmask]>
Reply To:
Date:
Wed, 24 Jun 2009 16:29:24 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (91 lines)
Inge

SN100C joints are typically bright and shiny, quite like Sn63 as you say.
The pix Steve posted are not.

The most likely explanation of grainy Cu/Sn joints (assuming wave soldering
or continuous dipping) is alloy imbalance caused by Cu washing into solder
from work. But the pictures don't look like that.

According to the alloy's specified composition you should be seeing mostly
Sn, some Cu, a little Ni. Ge and stuff like that burns out or goes unseen in
normal analysis.

The main point of the Ni is that it prevents "normal" dissolution of iron so
you shouldn't be seeing any Fe. If you are seeing gross amounts, this
indicates an abnormal event - likely a failure in integrity of pot/pump. I
would say that is the most likely answer here.


For completeness: If it isn't that then you have contamination from
somewhere else.

Do they have a regime for analysing pot (or if small capacity periodically
changing solder). The analyses should show a trend with throughput, so they
can predict pot change time etc. If the trend does not predict this event
then they have a (random) contamination issue. Good luck on finding that,
could be anything from people dropping holiday coins into pot, to someone
getting Aluminium tools to wet. 

Whatever, the answer is the same: change the pot, make a full analysis. The
answer either
- is a gross contamination from some elements which will be easy to spot,
and likely can be dismissed or you would have spotted already. 
-  or a trace contamination which has a big effect, but harder to see.

Of course there is a small chance the problem may lie in the PCB, thick Au
plating will do what you see, or they could have been HASLed with rubbish,
or a little P coming in from somewhere.

Regards
 
 
Mike

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Wednesday, June 24, 2009 1:55 PM
To: [log in to unmask]
Subject: [TN] SN100C I don't like the look of board pads

 Hi all,
 
will send pictures to Steve.
The two SEM images show SN100C boards that we got recently.
I don't like the look of the solder surface. Very grainy and
with lots of copper (darker spots). EDAX gives even fragments
of iron. My first thought was that the manufacturer had 
contaminated baths, which will be denied, of course. Anyway, 
my opinion is, that SN100C should be more like ordinary tin/lead, 
i.e nearly zero copper and a more shiny approach. 

/Inge
---------------------------------------------------
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
-----------------------------------------------------


***This email, its content, and any files transmitted with it, are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient, please contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited.

Messages sent via this medium may be subjected to delays, non-delivery, and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. Indium Corporation does not accept responsibility for changes made to this email after is was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.***

---------------------------------------------------
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