Another "Causerie" ? :-)

Bob K.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
Sent: Friday, May 31, 2013 4:20 PM
To: [log in to unmask]
Subject: Re: [TN] solderability factors

Of course it does. Like painting your house. You are pleased whole day until
sunset, then you say 'what the &%¤ ' what's going on. You have got water
molecules on the wall. All know. The comparison is not quite logical, but
points at the fact that even very small amounts of contaminations can have a
crucial impact in the INTERFACE.  I'm not a chemist, others can describe the
exchange of atoms and the importance of presence of zinc or
lead or whatever.   I thought that the various platings were homogenous
i.e. the nickel layer is all nickel, the gold is all gold etc. until I read
Safranec's books. Now I know that the final finish contains all sorts of
metal atoms and organics from base to top. You can identify metal atoms from
the copper all the the way and in all directions. This has a considerable
impact on the bands of crystal buildup. A demo of TOFSIMS on some
crossections gave me new eyes even if I did not understand half of the
metallurgy behind. Key words were crystal structure,  banded or lamellar
growth, band thickness, intergrain 'cementing' adds, organic and inorganic
contaminations.  Wassink has far from the knowhow you need. I have two
similar books, if you give me your adress I can send one to you. I do not
need twins. 600 pages on deep level (not high level, because we speak baths)

Inge

PS. Another must-have book is 'TheCanning Handbook' all about surface
finishes. !,100 pages.



On 31 May 2013 21:18, Louis Hart <[log in to unmask]> wrote:

> TechNetters, In concert with colleagues, I have been conducting 
> experiments to identify and assess the relative influence of some 
> process factors and parameters on the performance of printed circuit 
> boards with ENIG final finish in the J-STD-003B solder float test of S
coupons.
>
> These experiments have led me to conclude, or at least suspect, that 
> the plated copper, on which the ENIG is deposited, has a highly 
> significant impact on performance in the solder float test.
>
> We have a DC copper plating line along with a Reverse Pulse copper 
> plating line. Experimental results show significant difference in 
> solder float testing between the lines. I had been looking at the book 
> by Humpston and Jacobsen, Principles of Soldering, after having spent 
> some time with the TechNet-referenced books by Manko and Klein-Wassink.
>
> Humpston and Jacobsen's book, in the 2nd of the two chapters I read so 
> far, appears to say plating technique can affect solderability. Maybe 
> I'm misinterpreting something, since I'm often reading these things 
> around 11 PM.
>
> Anyone in the TechNet world able to help me understand if and how DC 
> copper might solder differently from Reverse Pulse copper, after ENIG 
> deposition?
>
> Louis Hart
> Compunetics
> Monroeville, PA
> USA
> [log in to unmask]<mailto:[log in to unmask]>
> 412-858-1232
>
>
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