LISTSERV - LEADFREE Archives - LISTSERV.IPC.ORG

LEADFREE Archives

November 2005

Leadfree@IPC.ORG

	LISTSERV Archives
	LEADFREE Home
	LEADFREE November 2005

	Log In
	Register

	Subscribe or Unsubscribe

	Search Archives

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 >>]

Subject:	Re: Reliability prediction of LF soldering
From:	Werner Engelmaier <[log in to unmask]>
Reply To:	(Leadfree Electronics Assembly Forum)
Date:	Wed, 16 Nov 2005 10:48:32 EST
Content-Type:	text/plain
Parts/Attachments:	text/plain (34 lines)

Hi Ofer,
I certainly know what MTTF and MTBF means, and for some things these concepts
work--MIL-HDBK-217 was built on them. However, for solder joints this is
different and that is why MIL-HDBK-217 does not work for solder attachments.
Solder joints are not equally loaded [the one's on the corners see
significantly more loading, everything else being equal]--that is why one always deals
with all the solder joints on a component. The solder joints on various
components have different loading conditions as well depending on component size,
solder joint geometry, and component power dissipation. The life of a compont's
solder attachment [all solder joints] is measured in terms of cycles not time
per se. That is why reliability models need to exist to determine an estimate
of the fatigue life of the solder attachments. There have to be different
models for leadless and leaded solder joints [here lead has nothing to do with Pb]
and different models for different solder alloys. We simply do not have the
data at this point for Pb-less solders to develop fatigue reliability models.

Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com


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

ATOM RSS1 RSS2

LISTSERV.IPC.ORG