Moisture / Drying Parts

[mrpackethead]

Looking for some opinions / infomaiton about handling parts before they are are reflowed

how do you go about drying IC's that have a MSL level of 3.. ( 168 hours or less )..   If you are only using them in batches of a few hundred at a time, but want too buy full reels, 1 week rapidly dies..

How difficult it it to keep things dry without having to reseal / vacumn pack all the time?

[hcglitte]

I use a dry cabinet. http://www.superdry-totech.com/

[MagicSmoker]

I have found that simply taping the bag shut with the original dessicant packets works fine, just make sure the tape covers the entire opening in the bag. I have parts with MSL-3 that have gone over a year without any change in the little moisture indicator card that is typically included.

[wraper]

I bought some clips like on the pic. Put the parts back with original desiccant and moisture indicator, roll an open end of the bag a few turns and put a few clips on it. According to the moisture indicators, works pretty well.

[CatalinaWOW]

Best solution will depend on your environment.  Which includes the weather, and also your soldering thermal profiles, climate control in your manufacturing area and reliability goals.  The 168 hour number covers everyone, and not everyone lives in a tropical environment, or uses the hottest, highest ramp temperature profiles, and not everyone requires the highest level of reliability.

Dry boxes and dry rooms are a sure fix.  As is re-baking per manufacturers recommendations before use.

For some environments doing nothing works.

Since it takes time and effort to dial in the actual minimum required for your situation I would recommend dry boxes.  They are cheap (can even be easily home brewed) and don't require excessive maintenance.

[D3f1ant]

Dry cabinet for often used parts, and resealing and vacuum packing with dessicant for long term. Always pack in the moisture indictator as well so you can verify the package integrity.
You can find cheap vacuum pack machines at kitchen shops.
Fairly easy to make your own budget drybox with an air tight container and a small desiccant based dehumidifier, the plug in to 'recharge' type ones.

[Smokey]

Dry cabinet for often used parts, and resealing and vacuum packing with dessicant for long term. Always pack in the moisture indictator as well so you can verify the package integrity.
You can find cheap vacuum pack machines at kitchen shops.

^
This..
Just pick up a vacuum sealer and some desiccant packs. 
Or don't worry about it and bake all your parts before sending them in the reflow oven.

Not sure how much it degrades them, but you can put used moisture indicator cards in the microwave and it seems to refresh them and they appear to still work after.   

[mrpackethead]

Have just bought a stack of air-tight containers, ( O-rings ), some desicant, and   i think with some careful management and some baking the problems will be resolved.

Going to talk to my upstream supplier and get them to ship each tray of CPU's in a seperate MPB.. IN theory we won't have many parts go past their MSL floor life time.

[wraper]

Have just bought a stack of air-tight containers, ( O-rings )

My experience with such containers is that most of them are crap, especially those made from sheet metal. Unless it is like a jar on the picture, presence of the sealing ring does not mean that container is airtight.

[mrpackethead]

Plastic box, and  i did some testing.. Stuck a plastic air valve into it, and filled it with compressed air to 10lb.  It was still at pressure 12 hours later..