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More moisture-sensitivity ??'s

Rich Ziebell


More moisture-sensitivity ??'s | 18 April, 2000


I am curious as to how other OEM's, CM's, etc., notify their component suppliers of not properly packaging and or labeling components that are moisture-sensitive. What about components acquired through distributors? Currently, I am having my Component Engineering group identify/verify the parts that are received in a dry-pack configuration but not labeled as such and they will then contact my Purchasing group to notify the negligent parts vendor. I am already receiving flak regarding these proposed changes. I guess I am looking to see the same presedent set somewhere else. Please let me know.

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Re: More moisture-sensitivity ??'s | 19 April, 2000

Rich: You should raise the issue until someone BIG smacks you!!!

We were getting deliveries from our distributors and virtually every part number had an opened dry pack. We kept SCAR'n the dudes until they came in and sat down. It took a while ... we're small change.

We found that our order break points were wrong. They were selling us the quantities we ordered. As fate would have it, the breaks on our order quantities were not the same as the breaks on dry packs. Go figure!!!

Admittadly this is a simple minded example, but it serves the point of sitting down with your suppliers may allow you both to understand and solve some of your packaging problems.

Good luck Dave F

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Glenn Robertson


Re: More moisture-sensitivity ??'s | 24 April, 2000

Rich -

I agree with Dave, except if you get smacked for doing the right things, find someone bigger to smack back. MS is a serious problem that affects many areas of a company. You might want to consider what I did, which is put together a presentation that explains what happens and why, and why proper procedures must be followed. You can then talk to anyone who will listen from operators to engineers to buyers. Maybe you can get some of them on your side. Good luck - you are not alone.

Glenn Robertson

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Re: More moisture-sensitivity ??'s | 24 April, 2000

Rich: Awww, don�t worry that you have to ship product. This moisture sensitive part thing is more important. ;-) And don�t worry that everyone is giving you guff and no one is supporting you. Yours is a thankless job. ;-) You got it right!!! This "collateral duty" of being the Moisture Sensitive Handling Implementation Guru is fun, fun, fun!!! ;-)

For us, this all started with multiwire boards, which have wires epoxied to the substrate, instead of traces. They sop moisture like a big dog that�s been chasin� a ball for a half hour in the middle of July. So without proper moisture control, those pups delaminate when they�re within 5 feet of a reflow oven. We added steps to our work instructions to bake these boards before assembly. Then, we started seeing TSOP rippin� themselves apart in reflow, but we didn�t realize it wasn�t the suppliers� fault. It was ours!!! We didn�t control parts well after partially consuming a dry pack. Then, we started baking things to demoisturize them and ended-up melting the trays and tubes. Gawd, it was a freakin� mess. We just stumbled from one problem to the next.

So, feel good!!! You�re way ahead of all that stuff. ;-)

The best analog for it that I can think of is implementing an ESD program in the mid-1980s. No one believed that a ESD problem existed. (Some still don�t!!!!) This process will be the same for you. The first thing you need is unwaiving support from the "boss" of everyone involved (as Glenn mentioned). The second thing you need a plan. (We used an ESD implementation plan as our model.) Our plan steps were:

1 Study and understand the technology MSP. 2 Gather scientific evidence of the economic value MSP control. 3 Establish an active MSP leadership team. 4 Develop a general implementation plan. 5 Write or adopt a set of realistic handling requirements. 6 Prepare a detailed statement of policy, including individual responsibilities. 7 Present plan to top management. 8 Establish top management commitment. 9 Develop details of MSP program management. 10 Present the program to middle and lower management. 11 Begin implementation of the control facilities. 12 Begin training the entire work force, including management. 13 Begin using facilities immediately after training. 14 Begin MSP statistical controls. 15 Begin internal audit of all manufacturing departments. 16 Report audit results to all levels of management. 17 Continuously improve the process.

It sounds like you�re doing a good job of breaking-down the problem. Don�t under-estimate the situation. This is not a straight forward problem. * It would be trivial if you could say that all QFP256 were Level 4 devices. * It would be simple if you could say that all QFP256 from Chips were Level 4 devices. * It sure would be nice if you even could say that all QFP256 from Chips with P/N bla bla bla were Level 4 devices.

But there is no logic to this, because moisture sensitivity levels are dependent upon the case material and the molding process. As you know, fabricators often have many assembly plants. So, as the laws of nature would have it, their processes are often different in each location. So, you can buy a part from a fabricator and receive part with different moisture sensitivity levels, depending on their source. We received a delivery that had some dry packed and some not dry packed parts, went nuts with the supplier, and found that they were doing what they were supposed to be doing ... because they assembled the same parts differently at their various plants. Fascinating!!!!

Another wonderful thing about working with moisture sensitive parts is when you�re sole sourced to a small fabricator that can�t spell J-STD-020. Who, at that point, probably hasn't classified the device and probably won�t classify it to meet your schedule. So, you have to classify it or default to a Level 6 classification. Ha, now that�s good, do that a few times and see if you get someone in your face!!!

The best way to get information on moisture sensitivity levels is to call the part fabricators and ask their quality department for the classification. Some fabricators post this information on-line. If they do (post it on-line), it could be more current than ... but then again ...

On the computer, we think of MSD as shelf limited parts, like batteries, spot mask, paste, and the like. We use a computer to flag the parts that are moisture sensitive. This: * Allows us to store material properly upon receipt. * Gives us a head start on de-moisturizing improperly packaged devices. * Highlights suppliers with problem packaging, so Quality and Purchasing can address the problem. * Provides information to better anticipate and schedule job tasks.

On the sunny side of the street, we have found that distributors are doing a better job of properly repackaging the devices.

On your job that takes about 13 hours run, but exceeds the 8 hour exposure limit set forth by J-STD-033, on a tape and reel BGA that must stay mounted on the machine through out the job, consider: * Dividing the BGA tape onto two or more reels, leaving all but one reel in the box until needed by the job schedule. * Buying the BGA with different packaging that will allow you to keep it on the machine for the full run time.

I�ve rattlin� on here. Dave F

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