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Fifo of Solder Paste

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#56707

Fifo of Solder Paste | 26 September, 2008

I am looking for a straight forward, inexpensive, idiot-proof method (idea) for adopting FIFO process for solder paste. The less I can leave open to human error the better. I currently use 4 different types of solder paste, and to be honest the way we do it at present lends itself to us being left with out of date paste.

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#56720

Fifo of Solder Paste | 26 September, 2008

what about tube (could be transparent) with opening at the bottom to pick up by operator and loading new fresh jars from top (vertical tower of solder jars). Each time when operator takes jar next one appears on the bottom etc.

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#56721

Fifo of Solder Paste | 26 September, 2008

That is basically what we use. Also, in the paste storage fridge we have a similar FIFO rack. Load from the back, pull from the front.

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#56722

Fifo of Solder Paste | 27 September, 2008

Can you have an outside vendor source it for you? Kind of like an "in house store". Besides paste, they would also supply you with all your other "dated" material. That way you only get charged for what you use. Then make sure your operators check the date before use. This puts the pressure on the in house store guy - not you. They can also handle all your little hand tools, brushes, and things like that. They woudl store everything in yout plant but would regulate it. It's not hard to do and pays for itself every year. We tried it and are hooked on it. Works very well.

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#56732

Fifo of Solder Paste | 29 September, 2008

Write the date on the tubes and grab oldest to newest.

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#56733

Fifo of Solder Paste | 29 September, 2008

Similarly, get some racks like this [ http://www.organize-it-online.com/itm_oia-canholder.html ] from the 'dollar store' and mod them to fit your jars and cartridges. We got platic racks.

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#56751

Fifo of Solder Paste | 30 September, 2008

What makes my statement silly? What is "IT" that I should be already doing. Sorry for not being able to read minds or read between the lines.

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#56757

Fifo of Solder Paste | 30 September, 2008

I've done it 3 different ways in my career (3 different places):

1.) Process Engineering was responsible for solder paste inventory (as well as all other process materials). That was a bad situation due to the blame factor.

2.) TOOL-CRIB control. This was a great situation actually. The Tool-Crib personnel were solely in charge of FIFO and issued paste to the lines...signed and dated. They also ensured adequate thawing and adhered to solder paste management guidelines.

3.) In-House Stores (see Chunks post).

I would also delve deeper into the "unrefrigerated shelf life" guideline for each of your solder paste suppliers. You'd be surprised....it's actually a bad thing to "re-refrigerate" solder paste. Leave it at room temperature, but make sure it's in an air tight container. It can be left at room temp. for up to a month. My only caveat here is...for those who don't have temp/RH controlled shops, you might need other equipment (like a Nitrogen cabinet).

Ultimately, FIFO is a discipline thing. At my current place, it is ISO mandated and the operators can get dinged if they're caught not following FIFO rules and paste management guidelines.

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#56783

Fifo of Solder Paste | 1 October, 2008

It depends on the usage , if it is regular and steady, only order when needed , we only order 2 jars when the last one is taken out of the fridge.One jar would last us about 2-3 weeks and it stays on room temperature. Ofcourse , you need a realiable supplier and an accurate reorder system , we use kanban it works fine

By the way , CK Pb-Head , what can go wrong if you "re-refrigerate" solder paste, any experience ??

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#56795

Fifo of Solder Paste | 2 October, 2008

Jani,

I got it from a very vague spec. from a solder paste supplier who stated, "It is not advisable to refrigerate an already opened container."

Sorry, but I don't have details why. My guess is, several temperature excursions, after the air-tight seal has been lost will change the rheology and composition and result in print inconsistency.

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#56796

Fifo of Solder Paste | 2 October, 2008

Not all paste formulators offer suggestions on handling the storage of opened paste jars, but some do. Here's a couple.

Storing Opened Solder Paste Containers * Once a jar or cartridge has been opened it should not be re-refrigerated. If solder paste remains in a container that has been opened, simply re-seal the jar or cartridge and leave it out at room temperature until it is ready to be used again. Re-refrigerating the paste can cause any moisture that has been absorbed into the paste to condense, which can then result in the aforementioned moisture-related problems. [AIM Tech-Sheet, Solder Paste Handling Guidelines] * Once a paste jar or cartridge has been opened, it should not be re-refrigerated. If solder paste remains in a container that has been opened, simply reseal the jar or cartridge and leave it out at room temperature until it is ready to be used again. Re-refrigerating paste can cause any moisture that has been absorbed into the paste to condense, which can then result in moisture-related problems. [D Suraski, AIM, dsuraski at aimsolder.com] * Open jars should preferably be closed immediately after cream has been taken out. Should there be no need for the use of more cream within the next few days, the cream preferably should be stored again in the refrigerator. [User's Guidelines Cobar No-Clean Lead-Free, Tin-Based Solder Paste X- Series] * Jars or cartridges should be labeled with date and time of opening. [Indium Procedures for Handling Solder Paste, Form No. 98039 R3]

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#56850

Fifo of Solder Paste | 8 October, 2008

Thanks for all the ideas and suggestions. One other side question. Does anyone have any experience of, or have any views on Paste conditioners? Basically the paste is removed from fridge and spun for 7 minutes or so then is ready for production.

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#56852

Fifo of Solder Paste | 8 October, 2008

Yes, the fine folks at Malcolm make this product.

Search the fine SMTNet archives for this. Type the word: "planetary", and you'll find it!

Trust me on this one.

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