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Solder Ball After Reflow Process

Views: 17444

#43350

Solder Ball After Reflow Process | 16 August, 2006

Hi All SMT Net Team Member,

I always have problem at MY SMT process and production side, Every time product running at my production side always found a lot solder Ball issue near the pad of SMT chip component. We had quite hard to do the trouble shoot to get the actual root cause of that But seems like my work hard is no result. Currently my process is on top side used solder paste and at Bottom side used epoxy process. My solder paste is Kester R811. my reflow setting is 130, 170, 185, 180, 190, 250.

Any one of you face the similar problem as mine ?, any one of you can solved my problem ? Is all the water soluble solder paste must have the solder ball after reflow ?

Regards Umar

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SWAG

#43351

Solder Ball After Reflow Process | 16 August, 2006

Is 811 lead paste? If so, it seems to me that your oven settings are getting into soak awful fast in zone 2 and your peak is way high. Unless you are doing a thick board or something like that, those oven settings seem aggressive and might result in solder balls. If you have a thermal profiler, get your oven recipe to match 811 profile recommendations. Aperture reduction or home plates in your stencils might also help but do one thing at a time...

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RDR

#43354

Solder Ball After Reflow Process | 16 August, 2006

Oven settings are meaningless here. What does the board see? It is the paste we are concerned about not what the heaters are running at hehe.

These solder balls are at the end of pad, which end? under the part or away from the part.

I believe you may have stencil issue myself, if profile is good.

common causes of balls are:

ramp rate too fast (splattering appearance) print misaligned (splattering appearance) bad paste either lot or type. (splattering or formed ball appearance) bad stencil design (could be single ball or splatter) poor paste handling and storage - excess moisture in paste

why are you worried anyway? after wash they should be gone since it is water soluble, if they are not gone then you also have a cleaning prob.

So get us the profile data such as max ramp slope, TAL, Max temp, and soak paramaters (how long at what temp)

Hope this helps, solder balls can be controlled we just need to see what you are doing. Russ

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#43355

Solder Ball After Reflow Process | 16 August, 2006

What do you mean by "near the pad of SMT component"? The end of the pad, side of the pad, or perhaps adjacent to the part body, between terminations? One solder ball per component, or many, perhaps of different sizes?

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#43398

Solder Ball After Reflow Process | 18 August, 2006

Hi SWAG/Rush/Steve,

Thanks for your response, Currently I am running with 811 lead paste. Actually this problem not only effect for one assy. I got 700 models runing at my company, but almost 50% of the model I have problem with solder balls issue.

The location of the balls is sometimes is near by of the part (is like splattering),end of the pad and even some is the sid eof the pad.

All my product is different PCB thickness, the minimum thickness is 4 layer and max thickness is 14 layer.

Yup correct, since my paste is water soluble the solder balls is easily removed at cleaning stage. but that's not to solved the problem. The only way to solved the problem is to kill the actual root cause of the problem. As I attend some seminar" Do it Right The First Time" and do prevent before happen.

Then right now I don't know what's the actual root cause of the solder balls.

Your kindly response to thismatter is very much appreciate.

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Chunks

#43401

Solder Ball After Reflow Process | 18 August, 2006

Hi Umar,

I believe you either are over printing these pads or the alignment of board and stencil may be off. Check your print right after your screen printer to verify either. If you are not over printing and your paste alignment is spot on, then you check after placement. Your placement machine may be over driving the part down so much it skews the paste off the pads - which may cause balling. Do you have an operator before reflow oven? If so, some believe they can place a part better than the machine and move the part around a bit - which could cause balling. If all above is good, then it must be your oven and it's time to reprofile.

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#43403

Solder Ball After Reflow Process | 18 August, 2006

Hi Russ, Can you please clarify on what you mean by "after wash they should be gone since it is water soluble,".....the flux would be water soluble or otherwise, how does that relate to solder balls being removed by cleaning?...i can see them being removed by the force of the cleaning chemistry, but cannot see how the flux type will affect their ability to be removed.

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RDR

#43406

Solder Ball After Reflow Process | 18 August, 2006

pretty much menaing Amol, that the balls are stuck to the board by flux and when you wash the flux the balls go away with it. If yopu are running no clean, then there will be no cleaning step and the balls will remain since the flux is basically untouched.

Did this help?

Russ

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RDR

#43407

Solder Ball After Reflow Process | 18 August, 2006

okay, very admirable, so you will need to answer the rest of the questions that were posed. Such as the actual profile, storage and handling, registration of paste, etc....

I would lean towards Chunks thoughts myself as well.

Russ

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#43415

Solder Ball After Reflow Process | 18 August, 2006

Chunks is a pretty with-it dude.

The only additional thought I have is the possibility of poor misprint cleaning. If they're wiping instead of spray or US washing they may be contaminating the boards prior to reprinting.

And yes, I know Chunks is not a dude, but I owed her one.

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Wave Master Larry

#43426

Solder Ball After Reflow Process | 19 August, 2006

LISTEN I'll have to disagree Steve.i think this Chunks person oversimplifies stuff and I dont like her style I'm surprised because most orientals do better with analyzing stuff.reminds me of some engineers at my place of employment.Again Im fighting the battle with regards to putting more flux on the PCB boards.they say its a weak formula but again how can alcohol be weeker than water? It just doesn't make sense.Now we use this new water based stuff, sure the joints are shinier but who cares about shiny?we got this lady on first shift who makes a good point. they're harder to inspect.

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Rob

#43436

Solder Ball After Reflow Process | 21 August, 2006

Larry,

Cut the racist generalisations it doesn't help anyone. & if you want to ramble on about evil capitalist flux vs tree hugging flux then set up a new thread.

Rob.

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Chunks

#43440

Solder Ball After Reflow Process | 21 August, 2006

Larry,

You always seem to twist things back to your wave solder process, ya nut! Anyway, why over simplify things when you are trouble shooting a process? The K.I.S.S. process was invented by your generation so I thought you of all people would like to keep it simple.

As for alcohol and water - they are just a medium for applying the flux. Again there probably is more rocket science to it than just that, but that's the bottom line. Shiny joints are good. Now maybe your lighting is too much? Generally if you change flux, solder, etc, part of that job is to create a good inspection environment. In your case, you lighting may be too bright.

And just to let you know - we're Asian not Oriental. Rugs made by Asians are Oriental rugs, cups made by Asians are Oriental cups, but the people are Asian. No blood, no foul; just so ya know. Although McDonalds does have an "Asian Salad". Not sure how that works or what may be in that salad. Soylent Salad anyone?

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Wave Master Larry

#43446

Solder Ball After Reflow Process | 21 August, 2006

LISTEN I loose track of all this politically correct business and dont really know anymore who is what and what is who.do I say black or african american oriental or asian.I dont know anymore! In my generation we could say just about anything without offending anyone.I apologize for anyone that i offend.i know that i do age myself because as most of you know here on the NEt my specialty happens to be wave Ive been around since inception and have a degree from Dover Soltec and wave has practiaclly been around for a century. There is no denying wave effects everything in the process and thats why I always revert back to wave.Many hear cant and dont understand that we all know waves the most technical process around.

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Chunks

#43453

Solder Ball After Reflow Process | 21 August, 2006

I believe you need to try to initiate the description of the criteria for requirements by developing a framework for the application architecture consistent with the planning corridor specified in our strategic initiative. Once bilateral goals are established, the engineer continues to undertake reinvention activities and new initiatives, we recognize the need to establish a framework to provide the necessary structure for optimal interactions and complementarily of the various reinvention activities. The framework delineates four major goals for reinvention: (1) maximize scientific opportunities through optimal use of resources and adminishere; (2) enhance engineering interactions with the scientific community through percussive maintenance; (3) clarify and streamline decision-making processes; and (4) focus internal operations on psychomotor outcomes and results. Each of these goals are further developed into specific reinvention objectives, and the plan is to use these goals and objectives as guide-posts as the engineer moves forward with the myriad of reinvention projects.

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#43456

Solder Ball After Reflow Process | 21 August, 2006

"...percussive maintenance"

Just for clarification, is this synonymous with "impact calibration"?

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Chunks

#43457

Solder Ball After Reflow Process | 21 August, 2006

Depends on the size of the hammer.

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RDR

#43459

Solder Ball After Reflow Process | 21 August, 2006

Well, Maybe.

hehehee

Russ

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