Well, you missed Sturgis, so the latter is irrelevant. We must have had the same Professor, except our postulation was there was 10 fold increase in things that would happen; most of them not favorable.
If you believe the hype about what pixie dust they add or don't add, then be concerned. IMHO, as long as you have a sufficient dwell time in your thermal profile for the flux (the activators, surfactants, beetle juice)to do it's job, but not so long as to burn off/ dry up before it gets to the reflow part of the curve: then don't worry; be happy Mon.
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Thursday, September 27, 2012 10:13 AM
To: [log in to unmask]
Subject: [TN] Flux Activation Temps

Hi,

 

I was looking though some paste datasheets which show a paste "Family"
available in different alloys. 

 

My Question:

 

Is a single flux formulation being used with these different alloys? It
seems so.

 

But the various melting point have a serious range. And I remember from my
college chemistry days that reaction rates double for every 10 C rise in
temp. (Is that still correct?) So I would expect fluxes to be relatively
"Inactive" al low leaded temps but then going super-fast at higher lead free
temps.

 

Can anyone clarify? Is it a real issue or hogwash-worthy.

 

Thanks,

Bob K.

 

 



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