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Moisture free storage units.

John Luckham

#4713

Moisture free storage units. | 7 March, 2000

I am looking for information concerning desiccator cabinets, could anyone help.

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Ioan

#4714

Re: Moisture free storage units. | 7 March, 2000

Hi John,

one supplier is Seika, www.seikausa.com. Check their McDry products.

Also, I'm pretty sure that a web search for "Moisture free storage units" will give you a lot of hits.

Ioan

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Bill

#4715

Re: Moisture free storage units. | 7 March, 2000

Hi, John,

Aerofeed Inc. is listed in Smtnet's Industry Directory as a manufacturer of nitrogen storage (desiccator) cabinets. You might try contacting them. They've got literature available to email you directly if you're interested.

Bill

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Tuan Bui

#4716

Re: Moisture free storage units. | 7 March, 2000

Hi John, Aerofeed,Inc. has the "Dry box" nitrogen cabinets. 215-257-1152 and they are in PA. I purchased one last year and it has been doing a wonderful job for our operations. I use it to store BGAs and micro BGAs after baking. To reduce the cost, I use regular compressed air, and it works just fine ( RH ~ 1-3 %).

Tuan

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Rich Z

#4717

Re: Moisture free storage units. | 7 March, 2000

John, I have read some of the follow-up's to your question and I am having several dry-cabinets made. Each, for under $500.00. Mcdry, a subsidiary of Seika Corp. is a vendor that has a solid background with moisture-free storage units. If cost is an issue, PLAS-LABS out of Lansing, MI maybe an alternative. www.plas-labs.com Ted Pella, Inc. may be worth a shot just to keep your quotes competitive. www.tedpella.com Good Luck!

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Dason C

#4718

Re: Moisture free storage units. | 12 July, 2000

John, currently, I am using the Eureka Dry Box and it is similar to McDry but cheaper and you can try and check www.aiko-group.com Rgds.

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larrys

#4719

Re: Moisture free storage units. | 13 July, 2000

Is using a refridgerator for storage an option?

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Dason C

#4720

Re: Moisture free storage units. | 13 July, 2000

Hi! Larry, absolutely "NO". When you move the component out from the refridgerator, the moisture will condensed to the surface. The Eureka Dry Box is different, it use special desicannt in the drying module to absorb the moisture inside the box and when it reach certain limit, the unit will start to burn the desicannt and at that time, the moisture will escape from the dry module to outside the box. This opertion is continuously.

Hope that it can help you.

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#4721

Re: Moisture free storage units. | 13 July, 2000

We gutted and rigged a rig to seep N2. Dawson's correct about using a standard frig tho.

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#4722

Re: Moisture free storage units. | 13 July, 2000

Tuan: Interesting. How do you have the compressed air rigged to your storage box? Regulator that's just open?

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Dennis

#24840

Re: Moisture free storage units. | 16 June, 2003

Hell Dave,

I am about to follow your example to rig a refrigerator into a N2 chamber. One of questions in my mind is how to you keep a constant N2 flow? We will have a N2 input, are we going to have some kind air output?

Thanks a lot for your help!

Dennis Xiong

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#24843

Moisture free storage units. | 16 June, 2003

John,

Maybe you know this already but I just wanted to highlight a few facts about dry cabinets. My experience is that many engineers are not well aware of the industry guidelines and sometimes will buy a dry cabinet without understanding the key features and what is the real benefit for their operations. The relevant guidelines can be found in J-STD-033A but this document can be quite confusing.

The first significant element is to establish when you will be placing MSDs in dry cabinets. For example it might be for temporary storage of partial trays and reels when they are removed from the assembly line after a changeover.

First it is important to understand section 4.1 : "Placing SMD packages, which have been exposed to factory ambient conditions for greater than one hour, in a dry cabinet or dry pack does NOT necessarily stop/pause the floor life clock..."

The effect of dry storage actually depends on the specific MS level of each component and the ambient conditions during the prior exposure.

If you have components classified level 4 then a dry cabinet at 10% will have a measurable drying effect in certain conditions, if you meet the rule for short duration exposure (section 4.1.2.1)

If you have components classified level 5 or 5a then you will need a dry cabinet capable of maintaining less than 5%RH. Once again the drying effect is only significant under certain conditions of exposure and subsequent storage (section 4.1.2.2).

And last but not least, some categories of components that are classified as level 4 and above will also have a limited storage life in dry cabinets at 10%RH even if they have never been exposed to ambient conditions (Ref; section 5.3.2.1 and table 7-1).

If you are interested I can recommend a few more suppliers of dry cabinets in addition to those already proposed.

Best Regards,

Francois Monette Cogiscan Inc. fmonette@cogiscan.com

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Dreamsniper

#24846

Moisture free storage units. | 17 June, 2003

Hey fmonnette,

What's wrong if I have a dry cabinet and baked all my components under 1-3%RH or say 5%RH regardless of their MS Level, whether they r level 4, 5, 5a, 6 etc.... What will be my problems in doing that process?

just for curiosity,

thanks

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#24852

Moisture free storage units. | 17 June, 2003

Good question, here is the short answer :

The problem is that dry storage is not the same as a bake process. If you want to bake saturated components, this should be done at higher temperatures. The IPC/JEDEC standard provides a table with bake temperatures at 40C, 90C and 125C. Take note that the default duration is 48 hours at 125C, 10 days at 90C and 79 days at 40C. This shows that it would take an infinite amount of time to bake components at room temperature if they are saturated with moisture, even in a 3% dry cabinet.

As I explained in my prior posting, the new standard does provide guidelines to account for dry storage but these rules must take into account the physical parameters of each component (MS level, body thickness) and the total history of exposure and dry storage. This is the only way to know when the moisture gradient is below the critical level at any point in time.

I know that some dry cabinet vendors have their own internal data to support other statements. However, it is important to understand that in many cases these internal studies are based on the old method of calculating moisture content by weight. For more than 5 years, all serious research has been done with the much more accurate moisture diffusion models. This is all the science behind the new guidelines of J-STD-033A.

If you are interested to read more into this I strongly suggest the following paper published by Dr. Shook from Agere Systems (former Lucent component division) : "Handling of Highly-Moisture Sensitive Components - An Analysis of Low-Humidity Containment and Baking Schedules", ECTC 1999. You can find a link to this document in the MSD Knowledge base at http://www.cogiscan.com, click on "list of publications" and scroll down the list.

Among other interesting experiments in this paper, you will find the example of a PLCC Level 5 (normally 48 hours of floor life) that was exposed for only 16 hours and then placed in perfect dry storage (at 0%RH), and this component exceeded its critical moisture content after 70 hours in dry storage. It remained above this level until a total of 210 hours had elapsed. In other words, under the old thinking that the clock of exposure time will stop in dry storage, you will generate component defects in your process.

I hope that this answers your question. Regards, Francois

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Desmond Bezuidenhout

#24880

Moisture free storage units. | 19 June, 2003

I assisted a company in the design and manufacturing of a +/- 700l cabinet utilizing a controlled nitrogen environment to purge. Any enquiry call +27 (0)16 9335747 or write to my mail.

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#24893

Moisture free storage units. | 19 June, 2003

I am currently working with Toyo Living, a manufacturer of Desiccant Dry Boxes. These boxes are specifically deisned for the electronics industry offering options of N2 Purge, or ultra-low flow, Out of spec Humidity alarms, Door Alarms, Data logging, and the capability of daisy chaining multiple cabinets together for network reporting, etc...

We also have models that incpororate a programmable low-temp bake, direcly in the dry box itself.

Toyo offers a large variety of standard sizes, and humidity ranges, but we also welcome your custom modifications/designs, Such as 'DEEP" cabinets equipped with feeder bases to accomodate mated components and feeders.

We do make a specific point of keeping our prices lower than some of the North American competition, as a result of the tough economic times.

You can visit our website at http://www.toyoliving.biz to find out more.

Regards,

Kevin McCarten Toyoliving.biz

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