We used to heat soak assemblies to be reworked for 2 hours at 90 deg C in a
calibrated oven, and re-heat them for half an hour after approx every 10
minutes of rework (if they took that long). Typically-used temperature ramp
rate for PCA's is 5 deg C/minute.

If you want to fine-tune the soak period to reduce the time in the oven,
stick a couple of thermocouples on the board attached to a data logger, and
see how long it takes for the board to reach the soak temperature.

Peter Duncan



                    "Rougeux, Scott"
                    <Scott.Rougeux@P        To:     [log in to unmask]
                    LEXUS.COM>              cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST
                    Sent by: TechNet        Aero/ST Group)
                    <[log in to unmask]        Subject:     [TN] FW: preheating assemblies prior
                    >                       to rework


                    09/27/01 03:21
                    AM
                    Please respond
                    to "TechNet
                    E-Mail Forum."






> Your input is requested on this issue.
> In regards to preheating assemblies prior to reworking them on the Solder
> Fountain/solderpot.
> We have been asked to look into preheating components or boards during
> rework. This opens many questions:
> *     What is the desirable preheat temperature?
> *     How is it measured?
> *     Where is it measured?
> *     How quickly can the assembly be heated?
> Thanks.
>

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