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Storing parts in Mcdry. Can parts stay in bags?

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james

#39396

Storing parts in Mcdry. Can parts stay in bags? | 31 January, 2006

Just want to know if it is ok to leave parts in the bag with an open end. I just hate for the operators to start leaving parts in the mcdry with just the tray. I could see them damaging them, label incorrectly or mixing them up. Just want to know what others are doing. Thanks

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#39495

Storing parts in Mcdry. Can parts stay in bags? | 3 February, 2006

Good morning James,

It depends on MSD class. Refer to J-STD-033. When you open dry bag shelf life starts. You have to mount all devices before maximum allowable shelf life time exceeds. Storing in dry cabinet capable maintaining RH<5% is equal to storing in dry box. Always store opened bags in dry room to stop shelf life clock. Generally speaking storing MSD�s in opened package is forbidden.

BR, Pavel.

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#39497

Storing parts in Mcdry. Can parts stay in bags? | 3 February, 2006

Hi James, As far as i can see, if you reseal the bags, then storing in a dry cabinet would be unuseful (as the McDry will no longer be able to absorb moisture from the components, and the dry bag will only be as effective as the desiccant in it)

i think the whole dry cabinet concept is to preven frequent dry bagging. also, when a component has exceed its MSL, keeping it open in a Mcdry for the speicifed time should reduce the moisture content in the component.

Pavel, can you please elaborate on "Storing in dry cabinet capable maintaining RH<5% is equal to storing in dry box"....is this good or bad??

P.S we are also contemplating getting a McDry.....any feedback for us?

Amol

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#39547

Storing parts in Mcdry. Can parts stay in bags? | 7 February, 2006

Good day,

J-STD-033A:

4.1.2.2 Moisture Sensitivity Levels 5-5a

For moisture sensitivity Levels 5 and 5a with floor life exposure not greater than 8 hours, a minimum desiccating period of 10X the exposure time is required to dry the SMD packages enough to reset the floor life clock. This can be accomplished by dry pack according to 3.3 or a dry cabinet that is capable of maintaining not greater than 5% RH.

5.3.2.2 Dry Cabinet at 5% RH

SMD packages not sealed in a MBB may be placed in a dry atmosphere cabinet, maintained at not greater than 5% RH. Storage in these dry cabinets may be considered equivalent to storage in a MBB with unlimited shelf life.

So, storing under relative humidity less than 5% is safe. Moreover, if you have rather good dry cabinet with good drying agent you can not bake at all. Storing only during 24 hours (<1% RH) can reset shelf life clock.

P.S. Look at Totech as alternative to McDry.

BR, Pavel

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#39549

Storing parts in Mcdry. Can parts stay in bags? | 7 February, 2006

I am looking at both totech and McDry.....both are at par with features....McDry is marginally more expensive than Totech

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