Hi everybody,

It appears that one of our component suppliers is converting it's SnPb 
plating process to one that is lead free.  I'm not totally up to date on 
the "lead free" topic, and I'd like to ask those who are familiar if there 
is reason for concern from the following announcement excerpts from ON 
Semiconductor:

"This is a General Announcement that ON Semiconductor is converting the    
 
External Lead Finish/Plating to a Pb (lead) Free Finish/Plating process.   
 
ON Semiconductor recognizes the increasing demand for environmentally      
 
friendly products. ON Semiconductor will convert the existing   
SnPb (Tin Lead) lead finish/plating to a Pb Free solution on a package by  
 
package basis. This conversion will take place from June 2003 to March 
2004,"

"All Products referenced by this PCN will use a Pure Matte Tin (Sn) lead 
finish. 100% Matte Sn is the predominate Pb Free finish in the industry. 
One of the benefits of using 100% Matte Sn, is it allows for "backward 
compatibility" in the manufacturing process. . When a device is described 
as "backward compatible", it refers to the ability for a manufacturer to 
use their current SnPb Printed Circuit Board (PCB) solder and assembly 
process. 

" Based on customer feedback and the uncertainties within the electronics
 industry, ON Semiconductor is modifying its plans for the package by
packageconversion to Pb (Lead) Free plating that was announced under 
Process
Change Notification (PCN) #12797 and the General Announcement (GA) #12770, 
both
 located at www.onsemi.com."

Is it true that the use of 100% Matte Sn would be "backwards compatible", 
and have no effect on soldering and reliability?  According to Jennie S. 
Hwang, Modern Solder Technology for Competitive Electronics Manufacturing, a high tin content would provide better wettability, but would also 
promote intermetallic compound formation and possibly lead to poor 
solderability.  According to my supplier, other component manufacturers 
are similarly removing SnPb from their lead plating. Any thoughts?  Thanks 
for the feedback.

Howard Watson
SMT Manufacturing Engineer

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