-----Original Message-----
From: Barmuta, Mike
Sent: Friday, November 05, 1999 8:55 AM
To: 'TechNet E-Mail Forum.'; [log in to unmask]
Subject: RE: [TN] Tin vs. Tin/Lead solder
Hi Rudy and Dave: You're both right!
Many things can affect the corrosion and oxidation potential of Sn. If we
keep our conversation focused on electroplated Sn, here are some issues that
will have an effect on its performance.
1. Base metal (Cu, Ni, Brass etc.)
2. Thickness of Sn deposit
3. Type of bath (acid, alkaline, matte, bright)
4. Grain structure/size of deposit
5. Impurities organic (brightners, surfactants, resists etc.)
6. Impurities inorganic (stannic Sn, Cu, Fe etc.)
Multiple factors come into play that influence the Sn coating performance.
Proper control and specifications are required to produce a good durable
final Sn finish.
Just my 2 cents.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett Wa.
425-356-6076
-----Original Message-----
From: Rudy Sedlak [mailto:[log in to unmask]]
Sent: Friday, November 05, 1999 6:50 AM
To: [log in to unmask]
Subject: [TN] Tin vs. Tin/Lead solder
Dave:
With all due respect to your exalted position in this area....
I have seen many many problems in the fabrications area caused by having
pure
Tin, as compared to having Solder, especially if the it is true solder, i.e.
that it is the true alloy, which seems to have profoundly better corrosion
resistance than merely "plated solder", which is nothing other than discrete
chrystals of Tin and Lead.
(Should I note that we make money and have products which have a life only
because they solve this issue... in selected situations:-)
And ignoring any ostensibly authoritative EMF tables, which I have found to
be effective in academia, and few other places (because they are meaningful
only when the electrolyte is deionized water), the solder seems to have
much
better resistance to corrosion than pure Tin, and especially plated Tin,
which seems especially "active".
If what I am saying is true, that Solder is much more passive than pure Tin,
you have the makings for a seriously pumping galvanic cell, which should
need
only an electrolyte to crank up, and deliver you Tin oxide all over the pure
Tin plating...
And remember, free advice is often worth what you pay for it...
Regards,
Rudy Sedlak
RD Chemical Company
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