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no clean flux + wave soldering issue

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#56211

no clean flux + wave soldering issue | 27 August, 2008

we have problem in setting the density of a no clean flux for using before wave soldering . first we dilute the flux but we have many short circuit problem between the pads of edge connector,then we densify the flux all the short circuit is removed but we have many taint on the pcb .so can anybody tell with what percentage we should dilute or densify the flux. if you have any article about setting a wave soldering machine according to the type of flux please let me know Thanks

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#56214

no clean flux + wave soldering issue | 27 August, 2008

I think WML ought to have some photos on how to do this...

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#56226

no clean flux + wave soldering issue | 27 August, 2008

what is WML ? can you please explain more

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#56232

no clean flux + wave soldering issue | 28 August, 2008

Sorry for the confusion... "WML" is a who... Wave Master Larry... He is a person on the forum who has a degree from Soltec? I don't remember... I was hoping he would have left a comment or some info that we could all learn by. (I am not sure how this is done either and the info would be good to know.) Best of luck to you.

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#56235

no clean flux + wave soldering issue | 28 August, 2008

Omid,

No-clean fluxes need to be used right out of the can without thinning. In the past with RA and RMA fluxes you could adjust or thin them to your desired density because they had plenty of solids up to 30%. No-Clean fluxes have a lot lower solid content in the range of 2-10% and are generally formulated to be used �as is�. To maintain the right activity level you need to check with the flux manufacturer for the acceptable density range and make sure that you use temperature compensation.

Increased density means more solids and will increase the residue potential on the boards. Lower density will lower solid content, but will also lower the flux activity level resulting in the shorts you see.

If you can't find the right balance between residues and activity level with your current flux you might want to do a search for a flux that give you the best of both worlds.

Google �No-Residue flux�

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#56237

no clean flux + wave soldering issue | 28 August, 2008

we have two similar pcb from two different pcb manufacturer one of them passed the wave soldering without any short circuit and residue and another one passed it with many residue . don`t you think that the type of solder mask from these two pcb manufacturer are different and cause this error if yes could you please tell me what type of solder masks do we have and the relation of them to types of flux?

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#56243

no clean flux + wave soldering issue | 28 August, 2008

Matt solder mask finishes gives the widest process window in view of potential amount of residues when using No-Clean. Shiny (glass like) finishes are more sensitive to residues due to lower surface area compared to matt finish. If the shiny finish is creating the shorts it might be that your flux is de-wetting on that particular surface creating:

Flux concentrations = residue Place with no- or not enough flux = shorts

To solder successful with no-clean you will depend a lot more on machine settings compared to high activity (must wash) fluxes. Again your flux manufacturer should have the proper recommendations.

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#56244

no clean flux + wave soldering issue | 28 August, 2008

My people said I was needed again here on The Forum. Thanks Mr Head for the goddos on wave soldering. It's a hard process to grasp and not every one nows how to adjust eveything properly. I can tell you regognize expertise when you see it.

That said. Omni, what kind of fluxer are you using? Do you foam or what? Alot can be made from know ing info. Double check your settings between your boards too. You no the ones you say are bad and good. Cause sometimes it's morethat just your fluxer settting. You preheats and wave setting can make a board look clean or not. Make sure all you setting are really the same.

To the rest of everyone else, The Master is IN!

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#56245

no clean flux + wave soldering issue | 28 August, 2008

Why yes, I regognize all the best.

WML, I have an idea... I am going to call it, the Dunker. Instead of anyone foaming, I will get the wave operators to throw the boards into a rubbermaid tub full of flux/gasoline mixture and send through to the wave. I will add iron for density. Would this be acceptable????

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#56253

no clean flux + wave soldering issue | 28 August, 2008

I guess you're adding the gas to keep the fingers clean - sounds likeyou got your threads mixed up on the Forum. Any way I would suggest not doing this. Gas is pretty flammable. I have pix of one our Hollis cleaning machines going up in flames caus eof too much iso from the wave. We were ablew to pull it outside with a forklift truck, but since it was made of plastic it just continued to burn. Now adding iron makes no sense to me. I could see if it would react with the flux or gas - but I don't see the significantce here. Also why dip whe you cna spry on th eflux some how? Again maybe you got your thread crossed up here on The Forum. Well, it's time for some Miller Lites. The Master is OUT folks!

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#56255

no clean flux + wave soldering issue | 28 August, 2008

Larry, I'm seeing a pattern here of you and fire!?!?! What gives?

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#56264

no clean flux + wave soldering issue | 29 August, 2008

I agree with Pat. We specify matte finish on all our boards. Once in a while our QC Dept lets in some glossy finishes in and then do their victory dance at the wave chanting "Wut ya gunna do about!?! Wut ya gunna do? Process outta control! Giggidy-giggidy-goo!"

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#56275

no clean flux + wave soldering issue | 29 August, 2008

What, Listen. Everyone know wave solders catch fire from time to time. I've only been a part of these fires a coupel times. Less than the number of fingers on my hands, so I don't think it's any different then anyone elses. Plus I havn't pulled out my hair yet and got most of my teeth, so I figger Im a head in this field. Ha ha ha.

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#56302

no clean flux + wave soldering issue | 2 September, 2008

if two boards with different solder masks give different results on flux residue level after soldering with the exact same machine settings than it is clear that one of the solder masks is not compatible with your no-clean flux. could be the solder mask is not cured sufficiently and parts of it interact with the solvent(s) of your flux. this types of residue is hard to wipe or clean off the boards. it looks like they are 'baked' inside the solder mask. use the solder mask that works.

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#56369

no clean flux + wave soldering issue | 5 September, 2008

Tell the board shop to increase the cure temp of the resist as it is undecured especially if you have waxy/greasy resiues on the board and a brown tar like substence in the solder wave itself. If undercured then solder will not flow off the resist properly causing bridges and solder balls Cheers Greg

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