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Warming up solder paste at start of days production

Hi, I wondered how people warmed up solder paste at the s... - Jul 22, 2004 by

Grant

#29596

Warming up solder paste at start of days production | 22 July, 2004

Hi,

I wondered how people warmed up solder paste at the start of the days production. I saw some paste mixers at a show, but only saw ones that mixed small solder paste tubs, not tubes. Can you get mixers that handle tubes.

They said these mixers allow the solder paste to be mixed up to get it moving for the start of the days production

Currently the guys are running a knead process on the printer a few times before the paste gets moving, however they need to use more pressure, and I am worried about it damaging the stencils.

Anyone have any info?

Regards,

Grant

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#29597

Warming up solder paste at start of days production | 22 July, 2004

All I got to say is a bowl and spoon and mix it up a little before u place it on the stencil. That works fine on our end all the time.

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Chris L.

#29598

Warming up solder paste at start of days production | 22 July, 2004

Hi Grant, The purpose for allowing the solder paste to reach room temp before production is to reduce the amount of water absobtion from the air. (e.g. a cold glass of water "sweats" on a humid day)The purpose for mixing is to make the viscosity more consistant as the paste and flux sometimes separate in storage. We too use tubes for solder paste. We have not had a problem with separation but we store the tubes on their side so that if there is any separation, the viscosity accross the tube will be fairly consistant. I am not aware of any mixers that will mix the paste in the tubes. Is the startup problems due to mixing or temp? If you are applying the paste to the stencil right out of the refrigerator, the paste is usually pretty stiff. It softens as it warms up but is also aborbing moisture. Most paste manufacturers recommend that you allow 1-2 hours for the tube to reach room temp before dispensing.

Hope this helps

Chris

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RDR

#29605

Warming up solder paste at start of days production | 22 July, 2004

Remove the paste from the fridge the night before, If you feel the need to knead we just put the paste on the stencil and work it a little bit with a spatula.

Russ

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Grant

#29610

Warming up solder paste at start of days production | 22 July, 2004

Hi,

It's removed from the fridge, and the tube is loaded into the stencil printer, however it's winter here right now, so it's still quite cold. It's Australia, so when I say cold, that's relative, however the room can be about 10 dec C in the mornings. So I wondered about a way to soften the paste before use.

A while ago when I was younger, I had the great idea of hitting the tube in the microwave for about 3 seconds. It worked, but then why I tried a half full tube, it generated plasma from the paste film on the sides where the tube has been used. That was exciting, and I stopped doing it after that experience.

I guess we should just keep doing some stencil kneads to get the paste working in the mornings!

Regards,

Grant

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KEN

#29611

Warming up solder paste at start of days production | 22 July, 2004

FYI

AIM has a patnented in-tube mixing propeller. Crazy, but it actually works.

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#29643

Warming up solder paste at start of days production | 24 July, 2004

Microwave? Try some steel wool next time. Are you cookin food in that microwave? I would love to see that documented into a process. You could look at changing the solder paste you use. Knead it up other than that mate.

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#29644

Warming up solder paste at start of days production | 24 July, 2004

Hi Grant,

There is a product known as the solder paste mixer which currently I'm holding

You can visit my website for more details of this mixer

www.novereng.com

Cheers Bob

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KEN

#29648

Warming up solder paste at start of days production | 24 July, 2004

I wonder what that would look like? BUILD DCOUMENTATION

Paste: OA XYZ-123 SOLDER PASTE. Note: Place refridgerated paste tube in Goldstar Microwave (3rd from the end of the break-room). Press "defrost" "forzen dinner". Do not defrost solder paste with the following: Large Burrito (small-half eaten is ok), 2 or more slices of pizza. Ok to defrost with 8oz coffee mug, but not 12oz.

Production Management: Defrosting solder paste will always take priority over the warm lunch experience of employees.

All persons: Please keep the microwave clean. Wipe up coffee spills, pizza saus splatter and solder splatter from the inside of the microwave after each use.

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#29652

Warming up solder paste at start of days production | 26 July, 2004

Grant,

The only thing that you really gain from refrigeration is a couple more months� shelf life. Refrigeration also seems to slow down flux separation.

I am not sure how your paste consumption is, but we use ours up way before the expiration date.

We started storing our paste in a cabinet over a year ago, and have had good success.

You gain two major things from NOT refrigerating #1 You don't have to screw around with the warm up thing #2 You have way less of a chance of introducing moisture.

If you are concerned about flux separation, then go to tubes instead of jars.

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#29653

Warming up solder paste at start of days production | 26 July, 2004

Grant,

I also have to say that the microwave thing is the coolest thing I have heard lately.Hahahahaha!! !

Here in the U.S. we have these comical Foster's beer comercials that are really really funny. I kept having flashes of those when I read this thread. Anyone that knows what I am talking about would surely get a chuckle from reading this thread.

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FD

#29664

Warming up solder paste at start of days production | 26 July, 2004

Can you use one of those hot-dog rollers (cookers?) you see in the corner convenient stores to keep the paste tubes moving to eliminate the separation?

Ya know, the cookers with the week old hot dogs on it that are all shrivelled up?

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Grant

#29666

Warming up solder paste at start of days production | 26 July, 2004

Hi,

Yes, it was quite funny, and everyone thought I was nuts, but it was something worth trying. It's often the weirdest ideas that work. The full tube was ok, but the half full one generated the plasma. That scared the hell out of us when it lit up!

So, yes, we use natural warming for solder paste now!

Regards,

Grant

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Grant

#29667

Warming up solder paste at start of days production | 26 July, 2004

Hi,

It was funny. The sight of 3 men standing around the microwave daring each other to push the start button, and then freaking out when the whole thing looked as though it was going to explode was funny.

I guess you have to try these things! Thought the story might be funny. Reminds me of when we tried to do vapor phase reflow on the kitchen hot-plate with a pasta cooker.

It worked, but we were so excited we kept taking the lid of the pot, and the vapor got out and condensed everywhere. It's really hard to clean up because it does not evaporate well at room temperature. The fluid coated the entire kitchen, and just where we were standing was dry. To pairs of dry footprints.

The worst thing is we were based in a post production company at the time, and had the MYDATA down the back making boards in a batch process. It was before we moved to our current building and put the full conveyer line in. So we really messed up the kitchen where clients normally prepare their food. It was a really trendy slate kitchen etc. So we desperately were trying to clean up before anyone came and noticed.

But it worked really well, and we reflowed two new prototypes the morning we had to fly to an important show, and we could demo the boards. Our batch convection oven had broken, so this was our only way to get the boards done for the show. It turned out to work, and is a good prototyping method when your desperate! The reflowed boards were perfect, as the process still worked the same.

It's funny the things you try when you have no choice, some things work, some don't!

Regards,

Grant

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Grant

#29668

Warming up solder paste at start of days production | 26 July, 2004

Hi,

That's a good idea. I might head down the the 7-Eleven, and try it!

I did not realize there is not too much to be gained by using refrigeration. We don't keep much paste in stock and buy it as we need it, so perhaps we should just keep it out ready. What shelf life do you get in tubes generally? More than 2 months would be fine for us.

Regards,

Grant

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KEN

#29671

Warming up solder paste at start of days production | 26 July, 2004

I have seen as little gain as 2 months and even up to 6 months additional time to end-of life. Treat solder paste as a perishible item. Note DOM and Refridgeration life and expiration periods.

You guys crack me up....now when ever I go to 7-11 I'll bust up over the hot-dog roller!

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Grant

#29678

Warming up solder paste at start of days production | 27 July, 2004

Hi,

Ok, and I will check that out. We do treat the solder paste as a perishable now, and after each day's run, we throw used paste out. That's helped a lot overall.

I agree on the hot dog rollers. I have always thought those things were a cool, but disgusting idea, however now I know of a new use for them!

Regards,

Grant Blackmagic Design

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#29681

Warming up solder paste at start of days production | 27 July, 2004

Grant, I know of a couple places that throw their paste out at the end of the day. I have worked in SMT for over 15 years and we have never thrown paste out unless it was contaminated, or dried out. We have never had a problem. If you ask me, I would say that you are wasting money. If you are that concerned about it, then order your paste in cartridges and buy empty jars. When the operator runs low on the stencil, have them dispense paste from the tube. When you use this method you are always ensuring that "fresh" paste is being added daily. At the end of the day scoop it off the stencil and put it in the empty jar. Label the jar with the current date and have your tech, or process engineers inspect it in three or four days. At that point they can "re-qualify" the paste fit for production.

As far as refrigeration goes, try an experiment. Keep a lot of paste refrigerated and keep one at ambient. Print 10 of each and run them side by side after a month or so of storage. I am willing to bet that you will see no performance differences. Even as far out as six months.

Anyways, that's my two cents.

Carry on.

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#29688

Warming up solder paste at start of days production | 27 July, 2004

Hell as for storing the used paste have someone bring in baby jars. Yes I agree thats alot of wasted money if you throw it away every day. Plus since I'm on the subject why not use a bottle warmer? I persoanlly store our paste in a mini-fridge (along with some of the operator sodas) and some other chemicals. We take out the paste in which is closer to expiration and let it stand for at least 24hrs (so one tube is kept out at all times in circulation). After being out for 24hrs the operator still has to work the paste for viscosity. But at the end of the day we plastic wrap it and put that in a baby jar with a chemcial label and that start with that paste the next day. As for new paste we got no problems for putting it down but once in a blue moon where it sticks to the blades (but who doesn't). Ok back to work and stop this nonsense hahahahaha.

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KEN

#29707

Warming up solder paste at start of days production | 27 July, 2004

Sr. Tech, when you say you have never had a problem, what exactly does that mean? How do you know you have never had a problem directly associated with your solder process? Do you actively measure your defect levels? How do you maintain traceability when transfering? How do you know you consistently label every container exactly right every time (even when new employees are on the floor)? Fitness-for-use is subjective. Especially, when dealing with solder paste. I have a saying: Solder is cheap. Process Control is priceless.

2 cents

All I'm saying is you may only print 1206 chips when the rest of the world is doing 0201's. You can't presume your process is transferable to everyone.

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#29717

Warming up solder paste at start of days production | 28 July, 2004

Ken, With all due respect: Surface mount is surface mount. Whether you are placing 0201's, or PLCC84's the basic concept is the same. So I would surely hope that for the most part my process is transferable.

I guess I was too broad when I said "we never had a problem" What I should have said is that we have never had any major failures that pointed to solder paste shelf life etc.

And yes we do actively monitor our solder PPM levels. They are rather low and have always been that way.(About 20 PPM)

You say paste is cheap ? Well, we run upwards of 100,000 grams a month............How much money would we lose if we pitched our used paste at the end of every shift ?

There are 2-3 people on each shift that I have personally trained on solder paste re-qualification. If there is something wrong with solder paste it is usually very obvious.Physically look at the paste.Is it dry? Is it visually contaminated? After that, how does it perform on the printer ? Is it hanging up on the blades ? Is it releasing from the apertures? Basically I tell them to use common sense.

By the way, we placed over 2 million 0201's last month.

Regards, Senior Peon

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KEN

#29727

Warming up solder paste at start of days production | 28 July, 2004

If it works for you, great. I would be concerned with "usually very obvious". Not all solders respond like you might think (rma's, OA's, NC's). Yours works. Mine may not. Do you control your facility humidity?

I find that common sense is not very common. Only 2 million parts (kidding). Are you in consumer product manufacturing?

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