Hi Bob!

Relax.  I can't speak for Pb-free processing, but I solder to
press-fits using Pb based material all of the time.  There is no issue
with the side wall damage possibility you bring up unless your boards
are unreliable anyway due to improper construction for the press-fit
design.  I doubt Pb-free introduces any other problems other than extra
heat and copper scavenging.  Actually, Pb-free press-fits are kind of a
problem anyway since the Pb is the primary lubricant for the process.  I
know I've seen Pb-free press-fits, but I know I've also read discussions
on the lubrication problem (which means to me that some people think
they have a solution, but it doesn't have tens of millions of
interconnections which is what it would take to convince me the kinks
are worked out).

I'd shove the wire in hole and fill the hole with solder as if it were
a soldered connection.  (But if you need to remove the part later, you
will be in big trouble!)

Wayne Thayer

>>> [log in to unmask] 03/26/07 12:07 PM >>>
Hi All,

Engineering wants to solder a few jumper wires to press-fit pins on
production 
boards. I am not completely comfortable soldering to press-fit pins and
want 
to get input from others because there appears to be conflicting
information 
between previous posts on this subject and IPC-610.

I have read concern that the heat from soldering (hand soldering in
this case)  
may compromise the press-fit connection - the theory being that the
hole is 
already physically deformed and under some degree of stress by design
of the 
press-fit pin and that heat may produce additional unintended stress.
Since 
we are soldering a jumper wire the entire hole will not be filled and
there will 
be a limited amount of heat introduced. Having never seen rework wires

soldered to press-fit pins on production boards, I don't know if this
is really a 
risk. Has anybody done this? The connector vendor is not willing to
comment 
because they don't have information about this, so that adds to the
unknown.

The second issue I have read about is that the design of the press-fit 

connection prohibits the formation of a properly wetted solder
interface 
between the pin and plated through hole. Since we are talking about a
solder 
connection to connect a jumper wire to end of the pin and not for an 
electrical connection of the pin to the board I don't think this
applies to our 
case.

On the other hand, IPC-610 does have a section (4.3.2.1) that gives
criteria 
for soldering press-fit pins so they must think it is OK. It states
that press-fit 
pins are not intended to be soldered, but if soldering is required it
gives 
criteria.

So, my quandry is...is soldering jumper wires to press-fit pins a risk
or not?

Thanks in advance for any and all help.

Bob

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