Hi Steve,

I can buy the argumet... 
I have the same experience with Tin going down in procentage and there is 
higher level of Lead in the soldering bath.
Thats why I found a Randy's question interesting and tried to explain for 
myself why he would get the results he got.
And I feel that this would be the best place in the world to discuss this 
kind of question and learn something new. :)

But the phenomena I mentioned earlier is that Tin and Lead physicaly 
separate from eachother and that Lead physicaly drops on the bottom of the 
soldering pot if the pot itself is not disturbed for a while. 
Meaning that the concentration of the Lead is higher on the bottom while 
concentration of Tin is higher on the top of the soldering bath.

Wouldn't this be the same phenomena why oil and water separate from 
eachother when not desturbed?

I feel like doing some experiments.... Wish I only had a time for that.. 
:)

*************************************************************************
Sasha Miladinovic - Production Engineering 
Amersham Biosciences, PCB Production, Umeå
Tel:      +46 (0) 90 150 232
Fax:     +46 (0) 90 138 372
E-mail: [log in to unmask]
*************************************************************************





Steve Gregory <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
2003-12-04 19:37
Please respond to "TechNet E-Mail Forum."; Please respond to SteveZeva

 
        To:     [log in to unmask]
        cc: 
        Subject:        Re: [TN] SnPb Solder pot composition


Hi Sasha!

In all the years that I've been wave soldering, Tin has been the only 
thing 
to go out of limits...and it's always been out of limits on the low side.

What I understand about that, is that dross is mostly composed of if tin 
oxides, and if you do a lot of waving with the turbulent wave on, you will 

generate a lot more dross than waving with just the laminar wave on, thus 
a greater 
depletion of Tin. The tin depletion is further magnified if you use 
something 
like Kleenox when you de-dross your pot because you won't be adding much 
new 
solder as the Kleenox is pretty good about separating the dross from the 
solder....

That's been my experience anyway...

-Steve Gregory-

Ed,

I like Your declaration about "cold" joints... :) I had a minor war i a 
earlier life with a Q-department about the definition.. :)

I'm not sure it any of us is right or wrong, but why would be Tin that 
drops?
Isn't it density and temparature that is the governing factors in this 
case?

Enyone outthere that can explain this? :)

*************************************************************************
Sasha Miladinovic - Production Engineering 
Amersham Biosciences, PCB Production, Umeå
Tel:      +46 (0) 90 150 232
Fax:     +46 (0) 90 138 372
E-mail: [log in to unmask]

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