Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Moisture Sensitive Devices

Gaz

#28416

Moisture Sensitive Devices | 5 May, 2004

I'm not in production, but I do repairs by replacing CSP & LGA components on PCB's.

Our components are supplied sealed in packs of 5 with a humidity indicator card and desiccant. I recently failed an audit by the company I do the work for because they say I should be storing the remaining components in an oven at 60 �C once I've opened a sealed pack, unless I use them within the time specified for their floor life as given from their MSL level. If I don't store them in the oven before their floor life exceeds then they say I need to bake them in an oven for 24 hours at 125 �C before I can use them.

Personally after reading a few articles I think what they are saying is wrong, and I'm having difficulty finding some answers to how I should be handling and storing moisture sensitive devices for people who do repairs, as everything I read seems to be aimed at the production side of things.

I think I understand some bits, but what I really want to know is:

How should I store the components I'm not using after they're out of the bag, and how long can they be stored in that way for? (Whatever the storage method is)

Do these stored components need baking before I use them now or not?

If I leave components out too long, how long do I need to bake them for, and how do I store them afterwards?

Is there a set baking time / temperature, or is it different for different types of component?

Are the components dead and buried after the 12 month shelf life has expired, or can I bake them as well?

Should my supplier know all this information and be providing me with it???

Is there anywhere I can get this information from in easy to understand plain English?

Can anybody help please?

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#28420

Moisture Sensitive Devices | 5 May, 2004

There's a pretty good listing of papers on MSD on the Cogniscan site [ http://www.cogniscan.com ]. Francois Monettet [ fmonette@cogiscan.com ] works there and can answer your questions. Consider search his postings here on SMTnet.

We have no relationship, nor receive benefit from the company referenced above.

reply »

Christopher Lampron

#28428

Moisture Sensitive Devices | 6 May, 2004

Hey GAZ,

The specification that addreses MSD's can be found on the JEDEC website and is JEDEC-STD-033A. I think this will answer all of your questions.

Hope this helps

Good Luck

Chris

reply »

Christopher Lampron

#28429

Moisture Sensitive Devices | 6 May, 2004

How should I store the components I'm not using after they're out of the bag, and how long can they be stored in that way for? (Whatever the storage method is) *reseal or store in a dry environment (dry cabinet must be >10% RH)

Do these stored components need baking before I use them now or not? * Depends on the MSD level (should be marked on packaging) Level 6 component need to be baked prior to asembly no matter what. Other levels should be OK if they were stored correctly.

If I leave components out too long, how long do I need to bake them for, and how do I store them afterwards?

*JEDEC-STD-033A lists a table of bake times dependent on the component body thickness. After bake, reseal with HIC and desicant.

Is there a set baking time / temperature, or is it different for different types of component?

*See bake time table in JEDEC-STD-033A This lists different times and temps for different body thicknesses

Are the components dead and buried after the 12 month shelf life has expired, or can I bake them as well?

*I believe that you can requalify components to extend the shelf life. I'm not sure what needs to be done, maybe solderability?

Should my supplier know all this information and be providing me with it??? *They should be providing you with the MSD level. The MSD label usually lists the max exposure and drying times required. (be careful of low temp carriers)

Is there anywhere I can get this information from in easy to understand plain English? *JEDEC-STD-033A

Good Luck

Chris

reply »

Rob

#28435

Moisture Sensitive Devices | 6 May, 2004

Let me pose this scenario and ask your opinion. My manufacturing plant is located in New Orleans. Since summer is close upon us, the humidity in my SMT room where the machines and components reside get around 30-50%RH. I've got this Siemens waffle changer that I fill with Intel 386 chips, flash chips (TSOP48), statis ram (TSOP54). Most of these parts have an MSD Level 4. Am I doing damage to these parts by leaving them in the changer (suppose they sit in the changer for over a month).

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#28440

Moisture Sensitive Devices | 6 May, 2004

Intel is very specific in their recommendations regarding moisture sensitivity.Check ou the following link: http://www.intel.com/design/Quality/icstorage/moist_classify.htm They also have plenty of other info in the developer side.They also have a document called Moisture sensitivity/dessicant packaging/handling of PSMCs.I got it from their site as well and it gives tons of great info on a wide range of packages. Needless to say that everything they post is backed by carefuly desinged experiments. The hypothetical conditions described in your message might give you some trouble down the road.Just out of curiosity weigh a selected group of componenets after a week of exposure in the RH conditions described in your message. Regards, Rob

reply »

fmonette

#28441

Moisture Sensitive Devices | 6 May, 2004

Hi Rob,

You might want to consider changing your current procedure. Components classified MSL 4 have only a 72 hours floor life at 30C/60%RH. Even if you consider the de-rating factor (table 7-1 in J-STD-033A), at 50% this maximum exposure time will increase only to 4 days for thin body components such as the TSOP you describe.

You will significantly increase your test yields and most importantly the reliability of your product if you handle your MSDs according the the standard guidelines.

Do not hesitate to contact me offline if you need additional information. By the way the MSD Knowledge Base mentioned in one of the postings above can be found at http://www.cogiscan.com, (instead of http://www.cogniscan.com).

Regards,

Francois Monette Cogiscan Inc. Tel : 450-534-2644 fmonette@cogiscan.com

reply »

fmonette

#28442

Moisture Sensitive Devices | 6 May, 2004

Hi Gaz,

Your customer recommendations seem to be a little bit outdated relative to the most recent industry standard. If you are interested I can send you an MSD Audit checklist that will help you assess your level of compliance.

I can also answer your specific questions if you prefer to give me a call. My company is actively involved in the joint IPC/JEDEC committee that publishes the industry standard for MSDs so I'm really familiar with this issue.

Regards,

Francois Monette Cogiscan Inc. Tel : 450-534-2644 fmonette@cogiscan.com

reply »

Rob

#28443

Moisture Sensitive Devices | 6 May, 2004

Okay... to follow-up on my scenario. Would it be cheaper to get a resealer with dessicants and humidity indicators or a baking oven, or both. Is there a moisture controlled storage cabinet (ideally 3'x6'x1' or in that vicinity)?

Would be interested to know the benefits and what companies out there offering these products.

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

#29164

Moisture Sensitive Devices | 17 June, 2004

Rob;

To answer your question regarding the availability of moisture controlled dry storage cabinets (Dry cabinets), yes such animals do exist. You can find some additional generic information regarding dry storage cabinets for the electronics environment here at http://www.drycabinets.com and some additional product specific information here at http://www.totechamerica.com where you will also find a listing of our local sales representatives.

We are in the business of supplying dry cabinets for the storage of moisture sensitive devices (MSD�s). The implementation of a procedure that works within the guidelines of IPC/JEDEC J-STD-033a (as Francois suggested above) is critical. Then the installation of a dry cabinet will provide you with a less labor intensive, more secure/effective way of storing/handling your parts since components while stored in a dry cabinet do not have to be bagged or sealed, and will be protected against humidity at a constant 1-2% RH (Well below the 5% RH called for by J-STD-033a).

If you would like any additional information or if you have some questions/comments please feel free to give me a call at 1-866-306-5480.

Kind Regards,

Kevin McCarten

reply »

Boundary Scan

ii-feed SMD Intelligent Feeder