This may be an obvious question, but does your board get a significant
amount of flux before going through the process?  Is it  the whole board
that gets these strings of dross or is it the leading edge or the trailing
edge of the board?  Does your solder sit idle before it is being used?  I
have seen in the past if I miss the leading edge of the board or the
trailing edge with flux, I see these same results.  My waves run at a
resting speed until there is a board coming through.  If there is too much
oxygen in the tunnel, a layer of dross will form.

Rob Williams





"<Jason M. Smith>" <[log in to unmask]> on 06/25/98 03:07:38 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to [log in to unmask]

To:   [log in to unmask]
cc:    (bcc: Rob Williams/Westell/EIT)
Subject:  Re: [TN] dross in the solder pot




Experts, I am currently getting alot of failures at my functional tester.
At my post solder station, I am noticing strings of dross across the pins
of connectors.  We are having to dedross the pot daily....for a no-clean
process and inerted atmosphering, I think this is a bit extreme.  Once, an
operator managed to accidently put stencil cleaner in the flux....could
this cause a reaction unable to be corrected without dumping the pot and
cause excess dross.  I initially thought we had too much exhaust drawing
all nitrogen away from the wave.  Our flux manufacturer did analyis and has
determined that it's not the residues left which is causing my bridges at
functional.  Is a type 'C' solder analysis going to tell me anything of
significance to my problem from any of your experiences?  Any
suggestions????

Jason Smith
Process Materials Engineer
Lexmark Electronics

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional
information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or
847-509-9700 ext.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################