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PCB post reflow cleaning

Just wondering what everyone's ideas are on the best cleanin... - Mar 22, 2004 by jdumont  

Russ is correct. ... - Mar 29, 2004 by davef  

#27707

PCB post reflow cleaning | 22 March, 2004

Just wondering what everyone's ideas are on the best cleaning chemistries for post reflow cleaning. I (like everyone) am looking for the most bang for the buck. Ive tried the big names, just looking for some input on anything else thats out there. Thanks

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#27746

PCB post reflow cleaning | 25 March, 2004

Residues from what type of flux are you cleaning?

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#27753

PCB post reflow cleaning | 26 March, 2004

No clean and RMA, both R0L0. Is it true that RMA type pastes are easier to clean than no-clean?

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#27754

PCB post reflow cleaning | 26 March, 2004

Dear Sir,

If you are looking for the best bang for the buck you will have to stop cleaning and use a no-residue paste instead of a no-clean. No-residue chemistry becomes totaly volatile in dwell time above reflow resulting in residue free boards.

I know you will not believe this but all i ask you, is to give this a try and all you can lose is one hour of your time but the gain could be a total solution for your cleaning problems.

Patrick Patrick@no-residue.com www.no-residue.com

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Mike Konrad

#27755

PCB post reflow cleaning | 26 March, 2004

Patrick,

When you say "no-residue" what exactly do you mean? Is there truely "no-residue" or is it "no visible residue"?

What type of ionic contamination results have you experienced? If you take a bare board that measures 0.0 NaCl and reflow it with the "no-residue" paste, will it still measure a 0.0? Have SIR and Ion Chromatography tests confirmed that there is NO residue?

I would be interested to know the results of your test data.

Thanks, Mike Konrad Aqueous Technologies www.aqueoustech.com

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#27756

PCB post reflow cleaning | 26 March, 2004

Id also like to know how this is possible. I am skeptical and would venture to say that it only looks clean but actually is not. Hopefully I am wrong and tests show there is actually no residue so we can save lots of $$$ here.

Thanks

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Mike Konrad

#27758

PCB post reflow cleaning | 26 March, 2004

jdomont,

No-cleans are more difficult to clean than RMA�s. Even though no-cleans have a lower solids content than RMA�s, reflow and soldering profiles are normally more severe than those used for RMA. It is interesting to note that our most of our customers are cleaning no-clean. In order of popularity:

# 1: No-Clean #2: OA (water soluble) #3: RMA

Mike Konrad www.aqueoustech.com konrad@aqueoustech.com

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#27760

PCB post reflow cleaning | 26 March, 2004

I know it is not easy to quantify zero. The biggest dilemma the no-residue technology is facing "disbelieve"

The most accurate proof to the fact that all solids disapear under heat is TGA analysis.

Test the no-residue in your facility under the right conditions and we can discus the subject furhter.

Patrick

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Mike Konrad

#27761

PCB post reflow cleaning | 26 March, 2004

Hi Patrick,

With all due respect, it is easy to quantify zero.

You made a claim that your flux produces ZERO residue. There are several industry-standards (IPC and Military) of determining the cleanliness of post-reflowed circuit assemblies. These test include Ion Chromatography, Ionic Contamination (R.O.S.E.) Tests, SIR, etc. These are the tests real users undertake. These are the tests mandated by multiple standards.

To make a stunning claim and then to suggest that a prospective customer buy the product and test it �under the right conditions� before engaging in further discussions is suspect. Claims like this are usually preceded with statements such as �Step Right Up Folks��

If you make a claim on a public forum, shouldn�t you provide supporting data publicly? The claim was ZERO RESIDUE. Please provide test results using industry test standards.

Mike Konrad

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#27763

PCB post reflow cleaning | 26 March, 2004

Mr. Dumont

I want to be very clear on a couple of points. The intention of my response to your thread was to bring you a solution for your problem "free of charge" The no-residue is not developed yesterday. The no-residue is developed in 1988. Because of this long history there is an abundance of test data available. One of the smtnet members is trying the complete no-residue line as result of a similar thread posted here. I count on him to post his findings in this forum.

This is simply a technology our industry need today to regain competitiveness.

Sharing technology and experience is the main purpose of this forum.

Patrick

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#27764

PCB post reflow cleaning | 26 March, 2004

Big Claims� No Data� Ummm�

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RDR

#27765

PCB post reflow cleaning | 26 March, 2004

Patrick, can't you just post the data? I noticed it wasn't readily available on the web site.

Russ

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Grant Petty

#27779

PCB post reflow cleaning | 28 March, 2004

Hi,

I would also be interested in this thread, but our problem has a different twist to it. We have good results from our reflow with Koki no clean paste, however when we pass the boards through the wave solder machine, the flux in that leaves a foggy residue on the bottom side of the board.

We are using a Soltec Delta C, and it's work ok as far as not spaying any flux onto the top of the board, so the component side looks great, however the bottom is foggy. The product is PCI cards, so they need to look clean and new when purchased by our customers.

Does anyone have any suggestions for what we can do post wave to eliminate this residue. I am worried that because we use no clean paste, we might have a problem washing the boards. Also the volume is about 200 units a day in a shit of the line, so any solution to this problem needs to be quick to do.

Hope someone can help!

Regards,

Grant Blackmagic Design

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#27782

PCB post reflow cleaning | 29 March, 2004

We are also having the same problem here. I was told earlier that it could be a problem with the solder mask during the raw board manufacturing level but then I noticed that the problem was only surfacing on boards that went through the wave. As far as the Koki paste can you email me here with the particulars? Address is jdumont@astromed.com Hopefully we can help each other out.

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#27786

PCB post reflow cleaning | 29 March, 2004

Patrick, I would like to try a sample of your product. Please forward me a link or email address for where I need to go to get one. That way I can see it perform myself. Thanks Josh

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#27788

PCB post reflow cleaning | 29 March, 2004

Thanks Josh,

email your company name, address and phone No. to sales@no-residue.com and a sample will be send to you.

Patrick

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#27789

PCB post reflow cleaning | 29 March, 2004

Grant & JDumont:

You should not have this white residue on your wave soldered connections, using VOC flux [but you know that, anyhow].

Applying too much flux is the likely cause. Other possibilities are: * flux contamination * solder contamination

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#27790

PCB post reflow cleaning | 29 March, 2004

Hi Dave, its not the connections that have the white residue. It is the surface of the board. The whole thing turns a milky white color. I have pictures if anyone would like to see them... Josh

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RDR

#27796

PCB post reflow cleaning | 29 March, 2004

The only time I have ever had this happen was with un/not fully cured solder resist. Only shows up after wave. I believe that is because of the higher temp than reflow but don't know for sure.

No help but what the hey

Russ

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#27798

PCB post reflow cleaning | 29 March, 2004

Russ is correct.

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#27799

PCB post reflow cleaning | 29 March, 2004

Well how can I correct this? Would baking the board prior to any operations help? Is this an issue I should get the PCB manufacturer involved with, or something that is common and just live with it?

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#27802

PCB post reflow cleaning | 29 March, 2004

Josh: Final cure of the LPI solder mask: 310*F for 45 minutes.

Your board fabricator needs to do a better job. Most fabs do not check cure, because the processes subsequent to cure are so brutal that the fab expects the following process to highlight all cure defects.

You can make the lighter colored blotches on your mask "disappear" with a "hair dryer". Be careful using heat guns, because the temperature on these devices is unregulated and can result in damaged boards.

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Grant Petty

#27806

PCB post reflow cleaning | 30 March, 2004

Hi,

Thanks for the ideas. With the solder mask curing problems, can you normally wipe off the white residue, as we can do this on our boards with our fingers. It's almost like the surface of the board has a "wet dried up" look to it, and it's a smoky white color.

If we can rub it off, do you think it's still the solder mask?

Regards,

Grant Blackmagic Design

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#27809

PCB post reflow cleaning | 30 March, 2004

If you can rub it off, it's unlikely to be a solder mask problem. Try the "excess flux, flux contamination, solder contamination" angle.

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Ed

#27844

PCB post reflow cleaning | 31 March, 2004

Hey guys. I've been manually dunking circuit boards for 8 years now. I too have the excess residue issue to contend with. I'm using a low solids - no clean flux from Kester (959). I have used solvents, thinners, windex and a multititude of cleaners trying to find what works the best. Kester recommnends one of their solvents but I'd like to know how to prevent the residue in the first place following wave soldering of thru hole parts. I sure there's a magic formula of flux quantity, temperature, time, etc... with maximum control of all parameters. I've recently found that actually cleaning the board with the very same flux that is used in soldering actually has an effect on the residue which minimizes the unsightly blotchy appearance. Then a light solvent finishes the job. This is very time consuming but necessary with the glossy finish masking we use on our boards. When we had flat finished boards year ago, and product looked great right out of the solder pot. Glossy finish from multiple vendors always gives ugly residue. There will problably always be residue, I just don't want to see it. Maybe an ultrasonic cleaner is the key? I'm open for suggestions and don't tell me the masking is not cured or the solder is contaminated with flux acids as I've ruled those out long ago. One answer is to get the flux right where it needs to be, only an amount that's necessary and nowhere else on the board. I'm still working on that theory every day. I'll get off my soap box now.

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paul pmd

#27849

PCB post reflow cleaning | 1 April, 2004

Deltawave flux pump continously runs while in run mode. After the pump there is a flux manifold distribution block. When switching between fluxes not all previous flux is purged or drained. When no clean is installed some cross contamination may occure when run is established. Purging of previous flux type from distribution block and hoses can occure via return line.

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Grant Petty

#27873

PCB post reflow cleaning | 2 April, 2004

Hi,

Thanks for the info. How clean can wave soldering get?

We are looking at a carrier that masks off most of the board when we run it through the wave, so hopefully this works.

Regards,

Grant Blackmagic Design

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Grant Petty

#27874

PCB post reflow cleaning | 2 April, 2004

Hi,

We tried that, as the Soltec has a spray fluxer that can flux just the connector part of the board, however we get really heavy solder deposits on the rest of the board that has no flux sprayed on it, so we seem to need to coat the entire board.

Also, the latest we know is the matt finish board is supposed to be ok, however all our board vendors use shiny solder mask, so that's also an issue.

So hopefully some kind of carrier with masking will solve the issue. I will let everyone know.

Regards,

Grant Blackmagic Design

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Grant Petty

#27875

PCB post reflow cleaning | 2 April, 2004

Hi,

We have the spray fluxer, and I will have a look for the manifold. The guys thought they had purged the system but it's worth checking.

Regards,

Grant Blackmagic Design

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Phil James

#27879

PCB post reflow cleaning | 2 April, 2004

Take a look at the downloadable paper on the subject of "White residues" available from NPL www.npl.co.uk/ei (Downloads) By the way, we also suffer from this problem!

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Ron Herbert

#27890

PCB post reflow cleaning | 2 April, 2004

White residue can often be caused by overheating the flux. When this occurs the flux is polymerized, basically turning it into an epoxy. You can usually determine if this is the problem by taking a pencil eraser to it. If it comes off, you have overheated the flux.

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Grant Petty

#27915

PCB post reflow cleaning | 5 April, 2004

Hi,

Thanks for the tip, and I will check that out! We have some heavy BNC type connectors, so they need a bit of heat, and this could be right that we are then overheating the flux.

Regards,

Grant Blackmagic Design

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