Al,

I would "preheat" the oven prior to inserting the parts to avoid the possibility
of thermal shock. If you cannot stop and start your conveyor then open the clam
shell after the oven is warm. Even though it will cool slightly that is better
than starting from a totally cold oven.

Brian Stumm
ETS, LLC

Chris Robertson wrote:

> Al,
> Is a cold oven, an oven with a cooling core inside?
> I have used a environmental chamber, which has a cooling core that dried
> my material with out heat. Kinda like the defroster on your car.
>
> Chris Robertson
> PCB Designer
> Lockheed - Martin Services, Inc.
> [log in to unmask]
> Ph/Fax (256) 722-2626
> ICQ# 13541566
>
> ----- Original Message -----
> From: TechNet E-Mail Forum. Alan Shaw
> <[log in to unmask]@NAPCOSECURITY.COM>
> To: <[log in to unmask]>
> Sent: Tuesday, September 14, 1999 4:34 PM
> Subject: [TN] Baking SOIC packages to dry them prior to reflow solder
>
> I have 5 year old plastic SOIC packages on reels and want to dry them out in
> an oven rather than leave it to the pre-heat of the reflow solder machine.
> Production asked for temperature and time for the SOIC to be in the oven.
> My initial thoughts are to put them in a cold oven and set the thermostat to
> 110'C and leave them baking for 4 hours. Then turn off the oven. Remove them
> when cool and use in the insertion machines the next day.
> Is the temperature and time suitable?
>
> The leads have passed a solderability test already, would the time in the
> oven have a significant effect on solderabitiy?
>
> Al Shaw
> ashaw at napcosecurity dot com
>
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