LEADFREE Archives

August 2001

Leadfree@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:
Re: Lead Free Board Finishes
From:
Keith Sweatman <[log in to unmask]>
Reply To:
(Leadfree Electronics Assembly Forum)
Date:
Sun, 26 Aug 2001 07:50:10 EDT
Content-Type:
text/plain
Parts/Attachments:
text/plain (27 lines) 
Jim,

The Sn-Cu equilibrium phase diagram indicates that the two phases present at
room temperature in the eutectic that occurs at around 0.7% Cu are beta-Sn
and the intermetallic compound, Cu6Sn5 (that "6" and "5" should be
subscripts).  That is the intermetallic I am referring to.   Under
non-equilibrium conditions and if the Cu content is hypereutectic there will
also be some primary intermetallic as well as eutectic intermetallic.
This intermetallic is clearly visible in cross-sections of soldered joints
and is distinct from the intermetallic layer that forms at the
solder/substrate interface as a result of interaction between the tin in the
solder and  the substrate metal.

Regards
Keith Sweatman
Nihon Superior Co Ltd

---------------------------------------------------------------------------------
Leadfee Mail List provided as a free 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 delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------

ATOM RSS1 RSS2