my experience:
End '80 beg '90 we use a solution like that. Along the assembly lines, next to P&P machines we use to get dry cabinets (cheap and simple cabinet) where to put inside of SMDs (reel & trays once out of MBB ) during the waiting time from one set up changeover and another.
The Cabinet was supplied by CDA (from 50 to 100 liter/minute max 20 PSI) and this was almost enough to meet the old Standard 786A. By playing with air flow and cabinet/door sealing it was possible to reach a RH% value even below 20% (recorded 24h/7d by T-Hygrograph instrument). Once J-STD-033 Handling of MSD has been adopted, those RH% was not more suitable to meet standard requirements.
N2 could be a solution instead of CDA, but it will be expensive and cabinet must be designed in order to contain high N2 consume.
Any way let's not forget Air contains 78,09% of N2 and 20,95% plus...to 100%. So in order to obtain a good level of dryness CDA is not so bad media. For sure forget to reach 5% RH.
We know, to prevent terminal leads oxidation N2 is much better then O2, but with good Clean and very Dry Air & if SMDs are not left inside dry cabinet for a long time, results are not so bad.
Regards..........GS
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