I don't understand your issue. The situation is the same whether

processing a double sided SMT PCB whether you use SnPb or SAC, just your

profiles will need to change for the solder.



Regards,

Chris



-----Original Message-----

From: Leadfree [mailto:[log in to unmask]] On Behalf Of Rich Lasko

Sent: 30 March 2005 14:14

To: [log in to unmask]

Subject: [LF] SAC 305 Reflow Question



Good morning everyone!  



 



I have some applications which are going to be double sided SMT with

minimal thru-hole additions.  Our process is to run the bottom side SMT

first (side 1), inspect, and then run the top side SMT second (side 2).

The overall board is approx. 8" X 7" and a 6 layer board.  My question

is: 



 



1.)     What is the nominal temperature in which a SAC 305 soldered SMT

joint from "side 1" will reflow again?  The reason I am asking is this

particular application has a couple 256 pin and 208 pin QFPs on both

sides of the board.



 



2.)     At what temperature range will these side 1 components begin to

reflow again?



 



 



Any assistance would be appreciated.



 



Thanks,



 



Rich 





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