Hello,

In ST microelectronics we asked experts from INPG (Institut National Polytechnic
of Grenoble) to calculate that phase diagram and the ternary eutectic :
calculated results :  Sn - 3.66w% Ag - 0.91w% Cu.

The phases present in the solder alloy are Ag3Sn , Cu6Sn5 and  Sn.

that phase diagram has been studied by  :

 K.-W.Moon, W.J.Boettinger, U.R.Kattner, F.S.Biancaniello, C.A.Handwerker -
 Experimental and thermodynamic assessment of SnAgCu solder alloys -
 submitted to Journal of Electronic Materials, April 2000.


regards

  Luc P.

______________________________ Reply Separator _________________________________
Subject: Re: [LF] Timelines for conversion to Lead-Free
Author:  kay ([log in to unmask]) at internet
Date:    10/25/00 11:07 AM


The exact ternary eutectic is still not fully agreed. I think on average
opinion that it is close to around 3.4%Ag 0.6%Cu. Of course in practice it
may not be that important - Erik's comments on microstructure describe well
the technical reasons for higher Ag content (and also the cost
disadvantage).

Kay

-------- ------------------------------------------------------
Erik E. de Kluizenaar
Philips CFT - Electronic Packaging & Joining (EP&J)
Building SAQ-p,  p/o box 218,  5600 MD Eindhoven - The Netherlands
Tel/Fax: (+31 40 27) 36679/36815;    E:mail  [log in to unmask]
PHILIPS worldwide homepage:  http://www.philips.com
Internal PHILIPS only:
http://pww.cft.philips.com/cfteurope/electronics/elpajo/index.htm
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