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Solderball Removal

ianchan

#20040

Solderball Removal | 23 May, 2002

Hi mates,

need your advise here. we have solderballs on a model due to neglect by stubborn folks to follow issued process control instructions.

the post-reflow PCBA has solderballs stuck in the NC flux residue and is not in compliance to IPC-A-610C specifications on solderballs acceptance criteria. we used NC paste "Heraeus F365 - 63/37" type.

anyone have any experience in removal of such solderballs stuck in "harden" NC flux residue?

your help is appreciated!

PS: 1) we tried using a portable ultra-sonic vibration machine but it dun work.

2) we dare not put it to the max vibration coz of fragile lead components that may "vibrate-drop" off.

3) anything more stronger than "Genosolv 2004"(NC cleaning solvent) seems to corrosion away the surface layer on the IC leads. which gives a porous dull metallic apperance.

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Mike Konrad

#20051

Solderball Removal | 23 May, 2002

Solder balls can be removed with most cleaning systems, batch or inline. Ultrasonic will work but may also cause other problems. A high pressure spray-in-air cleaning system with a chemical additive (for no-clean removal) will work best. If you normally do not clean your boards at all, and if this is (hopefully) a one time effort, consider a contract cleaning service.

In addition to manufacturing cleaning equipment, we operate a contract cleaning service. In addition, there are other companies who provide such services. Contact me offline and I�ll provide you with details.

Mike Konrad (909) 944-7771 www.aqueoustech.com konrad@aqueoustech.com

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#20052

Solderball Removal | 23 May, 2002

Not intending to undercut Mike's offer, but to compliment it. Consider asking Heraeus for guidance about cleaning the residues from reflowing your paste. Some NC flux res: * Cannot be cleaned. * Can be cleaned after a relatively short period of time after soldering. After that period, the res becomes very hard and glassy. * Can be cleaned, but leave behind residues that are very corrosive. * Can be cleaned well using a saponifier with a good surfactant constituent that are heated 140-145�F.

Actually, we just wash the solder balls from our boards using an aqueous cleaner. A gross filter in the washer collects the solder balls. Periodically, we dispose of this filter as a hazardous material. Works GREAT.

According to Microcare [ http://www.microcare.com/product/pg-fastdry-solvents.html ], Genesolv 2004 might not be a good choice for a variety of reasons. Scratching the surface, Microcare says, �A fast-drying azeotrope of HCFC-141b and methanol. Hugely popular. Aerosol only � available for use in vapor degreasers in Europe until 2001, and in certain exempted categories until 2006, but banned in the U.S. and Canada after 2002. Mainly used as a defluxer of rosin fluxes; not compatible with most no-clean fluxes. Very aggressive. Mil-spec approved. Superior toxicity ratings. Low aroma. Nonflammable. Neutral pH. Affordably priced.� And all of that becomes particularly scary when you consider that Microcare sells the stuff [Genesolve 2004].

Yano, you really should consider working to improve your soldering process so NOT to leave solder balls. It probably would be a lot less work and lower cost.

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