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Dry Box Storage

Views: 1127

Hoss

#39147

Dry Box Storage | 17 January, 2006

I know this has been hashed from looking in the archives but there is little in regards to creating drybox storage using clean, dry air (CDA).

If my factory can supply CDA through and air dryer at <5%RH, why wouldn't I buy up a used, ESD safe storage cabinet and fit it with my factory CDA.

Assume that we have a redundant compressor setup and a way to monitor RH. Oh - the cabinet is ESD safe.

Cogiscan, Seika et al - Kindly do not respond.

Thanks.

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#39160

Dry Box Storage | 18 January, 2006

That is pretty much what we did at a previous employer. This was a medical device manufacturer so the validation had to show that the system met the current (circa 1985) standards. 'cept we used a converted fridge.

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adlsmt

#39187

Dry Box Storage | 18 January, 2006

That is an interesting idea. Would the air circulation increase the rate of oxidation on the component leads?

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#39191

Dry Box Storage | 18 January, 2006

Don't know why it would....the available oxygen shouldn't change any. You could always use nitrogen if you were worried about that. ;)

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GS

#39215

Dry Box Storage | 19 January, 2006

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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