We have been seeing boards come off our reflow oven with bow and twist
    that exceeds IPC specs.  Our vendor insists that we are the only
    customer that complains about this.  We had our reflow oven calibrated
    and it looked fine.  The only thing about the profile that may be
    suspect is the cooling rate may be a little too fast.  According to the
    vendor, they put all of their boards through a de-warping process.
     The vendor has tweaked their de-warping process to cool slower in an
    effort to make the problem go away.

    My question is:  This is our first bout with warping, what should we be
    looking at for a cause?  Is it normal for a pc board vendor to have to
    de-warp boards?


    Regards,

    Ken Nevius
    Veeder-Root
    Altoona,  Pennsylvania

################################################################
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's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################