i am still the believer of RP system from Mitsubishi chemical (the  
one take away the oxygen and other corrosive gas, not just  
moisture... make sure you don't accidentally get the biology type,  
which leave the moisture in the unit).  Yes, it is pricy and need  
moisture barrier bag and vacuum pack, but it you have sensitive  
device/board, it is still money well spend IMHO (especially, for  
temperature sensitive stuff).
jk
On Sep 11, 2018, at 7:11 PM, Robert Kondner wrote:

> Wayne,
>
>  Thanks but I had zero luck searching through the archives,  
> probably pilot error.
>
>  But I looked into IPC1601 and it did say "Air Flow is Critical". I  
> wonder how that jives in a vacuum? I also saw some references to  
> the need for air flow to heat by convention, that makes sense.
>
> Backout at 125C can degrade finishes so I would like to dry out  
> PCBs in a dry box. I have seen info from McDry showing rates of  
> moisture removal. Seems the times are about 10 - 30 hours at 30C.  
> This data is for ICs, I am curious what might apply to PCBs. I  
> would much rather dry at 30C for a long period of time than 125C. I  
> am wondering if anyone knows of any data.
>
> Thanks,
> Bob K.
>
> -----Original Message-----
> From: TechNet <[log in to unmask]> On Behalf Of Wayne Showers
> Sent: Tuesday, September 11, 2018 6:30 PM
> To: [log in to unmask]
> Subject: Re: [TN] PCBs in dry chambers
>
> http://listserv.ipc.org/scripts/wa.exe?A0=TechNet this will also  
> show the monthly archive tabs