Dear P,

Fretting has nothing to do with wave soldering, as far as I understand.
I have spent lots of hours studying fretting on multiconnectors for
aircraft equipments. Imagine a contact male pin mated into a female fork
or sleeve. There is a contacting pressure, specifically rather high per
sq unit. Now, when exposed to vibration, the metals may slide against
one another, small increments, just microns. The friction heat in the
matrix is so high, that you get millions of micro welds. These are
cooled down in nanoseconds, fractured, reheated, fractured, reheated,
and after millions of such events, the metal begins to change character,
oxides and other microscopic products deteriorates the crystalline
order, and the surface metal begins to fall apart by kind of fatigue.
Microscopically, it looks like corrosion, therefore the name fretting
corrosion. I speak about gold plated beryllium copper or other metal
concepts. Even tinned contacts are involved, but are less prone to
fretting because of the more ductile properties. Fretting can be a very
severe problem, can cause electrical discontact and catastrophic
failures. This is my amateur explanation. I have a friend who disputed
on fretting mechanisms, got her thesis, so I can perhaps give you more
specific answer later. 

Inge

-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För P. Langeveld
Skickat: den 16 maj 2007 17:27
Till: [log in to unmask]
Ämne: Re: [TN] AC Outlets in China

Technetters,

Is there anybody who has experience with fretting/corrosion of metal
parts in wave soldering by the use of lead-free (SAC) solder wether or
not in combination of VOC-free fluxes?

P. Langeveld
Soft Soldering Processes
The Netherlands

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