Dear Valdimir,
Can you please clarify your E-mail below? Do you think I may be dealing with black pad?
Regards,
From: Igoshev, Vladimir [mailto:[log in to unmask]]
Sent: Wednesday, June 18, 2008 10:55 AM
To: [log in to unmask]; Kane, Amol (349)
Subject: Re: [LF] [TN] SN100 for Reflow Application
Hi Amol,
The thickness of intermetallic layer does not indicate whether you might deal with BP or not, but the fact that you got laminate cracks does.
Regards,
Vladimiir
----- Original Message -----
From: Leadfree <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Wed Jun 18 10:33:12 2008
Subject: Re: [LF] [TN] SN100 for Reflow Application
Hi Pete,
We will not be using the DICY cured laminate in a LF process. It wont withstand LF process temperatures. yes, we did observe a P rich area and a rough Ni surface. However, a presence of a thick intermetallic layer rules out black pad. it does reflect a plating bath that Is potentially unbalanced wrt the chemical composition. However, the SnPb version of the board is also ENIG and from the same board supplier. Therefore all things being equal (plating wise), we see cracks only with the LF assembly.
All the obvious SMT process steps (Solder deposition, solder ht, reflow temps etc.,) were checked to ensure accuracy.
Regards,
Amol
-----Original Message-----
From: Pete Houwen [mailto:[log in to unmask]]
Sent: Wednesday, June 18, 2008 9:53 AM
To: [log in to unmask]; Kane, Amol (349)
Subject: Re: [TN] SN100 for Reflow Application
Amol,
If you are joints that much more prone to failure, don't rule out your process
just because they aren't failing during the process.
Are these ENiG plated boards? When you did your cross sections, did you do
any analysis of the interfacial? Are you getting P-enriched zones? Are there
voids - large or micro, in the joints or balls? Are the soldermask openings and
registration the same on both versions? Do you inspect the paste deposition
to make sure the stencil is releasing the lead free solder as it did with tin/lead?
While the fractures aren't showing up until you apply mechanical stress, the
process itself could be weakening the joints, and that doesn't always show up
on all of the balls, or even the same ones consistently. Though pad cratering
indicates that at least at those pads, the joint was stronger than the laminate.
Be careful using dicy cured epoxies with lead free process temperatures. A
whole 'nother can o' worms.
Pete
WARNING: Export Control
This document may contain technical data within the definition of the
International Traffic in Arms Regulations (ITAR), and subject to the Export
Control Laws of the U.S. Government. Transfer of such data by any means to a
foreign person, whether in the United States or abroad, without proper export
authorization or other approval from the U.S. Department of State is
prohibited.
CONFIDENTIALITY NOTICE:
This e-mail, and any attachments, is for the sole use of the intended
recipient(s) and may contain information that is confidential and
protected from disclosure under the law. Any unauthorized review, use,
disclosure, or distribution is prohibited. If you are not the intended
recipient, please contact the sender by reply e-mail, and delete/destroy
all copies of the original message and attachments.
Thank you.
-------------------------------------------------------------------------------Leadfee Mail List provided as a service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL)
Search previous postings 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
-------------------------------------------------------------------------------
WARNING: Export Control
This document may contain technical data within the definition of the
International Traffic in Arms Regulations (ITAR), and subject to the Export
Control Laws of the U.S. Government. Transfer of such data by any means to a
foreign person, whether in the United States or abroad, without proper export
authorization or other approval from the U.S. Department of State is
prohibited.
CONFIDENTIALITY NOTICE:
This e-mail, and any attachments, is for the sole use of the intended
recipient(s) and may contain information that is confidential and
protected from disclosure under the law. Any unauthorized review, use,
disclosure, or distribution is prohibited. If you are not the intended
recipient, please contact the sender by reply e-mail, and delete/destroy
all copies of the original message and attachments.
Thank you.
|
