Posting for Kay Nimmo:

From: "Kay Nimmo" <[log in to unmask]>
To: "Leadfree Electronics Assembly E-Mail Forum." <[log in to unmask]>

The ISO 9453 standard defines specific composition ranges for each alloy
rather than general tolerances; e.g.=20

Sn-5Sb can have 4.5 to 5.5%Sb
Sn-4Ag can have 3.5 to 4.0%Ag
Sn-1Cu can have 0.45 to 0.9%Cu

I imagine these composition ranges were set to limit significant changes
to liquidus/solidus. Newer lead-free alloys are in the process of being
added to the standard.=20

Kay Nimmo


-----Original Message-----
From: Lynn Norman [mailto:[log in to unmask]] 
Sent: 29 May 2001 17:03
To: [log in to unmask] 
Subject: [LF] Lead-free tolerances


We're starting our in-house evaluation of lead-free solder.  The
composition
we are initially looking at is 95.5Sn-3.8Ag-0.7Cu.  Our current spec for
SnPb has a +/- tolerance of 0.5% on the composition.  What kind of
tolerance
will the lead-frees have?  How much of an effect will the variability
have
on solidus/liquidus temperatures?  Just curious as to what others are
doing.

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