Brian:
Based on your experience, is there a need for a saponifier in the cleaning of OA fluxes to ascertain residue removal from difficult parts to clean such as low BGAs and flip chips?
Regards,
Ramon
> -----Original Message-----
> From: Brian Ellis [SMTP:[log in to unmask]]
> Sent: Wednesday, May 05, 2004 7:33 AM
> To: [log in to unmask]
> Subject: Re: [TN] (2) [TN] OA / RMA
>
> YES!!!! Bingo!
>
> Brian
>
> Graham Naisbitt wrote:
>
> > Brian
> >
> > Thank-you for that information, it is most helpful albeit a little late for
> > the customer in question - 1998!
> >
> > ...but let me get this straight - the residues of an OA flux (some or all?)
> > will serve to lower the ST sufficiently to assure good cleaning performance,
> > yes?
> >
> > Graham Naisbitt
> >
> >
> >>Sorry, Graham, but I insist. The residues of the flux itself contains a
> >>large excess of surfactants which lower the surface tension of the wash
> >>water to ~25-30 dyne-cm. Most saponifier solutions have an ST of 30-35
> >>dyne-cm. The only effect that saponifiers would have is to replace the
> >>acid residues with equally corrosive alkaline ones. It's a waste of time
> >>and money adding saponifiers. Furthermore, if your wash cycle contains
> >>saponifier, you must have a second water-only wash cycle before the
> >>rinse starts, to wash off the saponifier residues. Not all machines
> >>permit this. What I said in my previous message still stands.
> >>
> >>A pre-rinse in a chelating neutraliser (which is NOT a saponifier),
> >>BEFORE washing is beneficial. This can be in a static hold tank. This is
> >>a time proven method. This is demonstrated in the streaming video at
> >>http://www.protonique.com/video/ (this is quite old and the components
> >>are BIG, but the principle is still valid).
> >>
> >>Brian
> >>
> >>Graham Naisbitt wrote:
> >>
> >>
> >>>Hello Mike
> >>>
> >>>I knew I shouldn't have.....but can't help myself......
> >>>
> >>>I agree with you, but what I am referring to is the use of a closed-loop
> >>>pure water 'OA' type process where no chemistry is used only pure water.
> >>>
> >>>Surfactants to my knowledge are not used in isolation, saponifiers (soaps)
> >>>will be needed as well, and make sure the surfactant has excellent
> >>>rinseability (silicone base is not a good thing in this instance). Whatever,
> >>>it is wash chemistry and there will be an effect on the life of the filter
> >>>beds and the transfer of wash 'chemistry' getting into the rinse zone(s).
> >>>Clearly the use of saponifiers that generally have to include surfactants
> >>>for that very reason, require a somewhat more complex cleaning system.
> >>>
> >>>
> >>>>From my perspective, the pure OA approach, as Brian alluded to in his reply,
> >>>
> >>>isn't adequate to ensure thorough cleansing on high density low stand-off
> >>>devices.
> >>>
> >>>...ah! That perennial question: How clean is clean?
> >>>
> >>>Graham Naisbitt
> >>>
> >>>
> >>>
> >>>>Hello Graham: I have to disagree with your statement regarding the need for
> >>>>saponification to get under low standoff components. The need was to reduce
> >>>>surface tension which can be achieved with a surfactant. With a surfactant
> >>>>the surface tension of the wash water is lowered allowing it under low
> >>>>standoff components to flush out OA flux residues. It also does not leave
> >>>>behind the saponifier chemistry.
> >>>>Saponification is quite a different animal than a surfactant. The saponifier
> >>>>converts non water soluble residues to hydrophilic or water soluble ones.
> >>>>The saponifier typically has a surfactant as part of it's make up to allow
> >>>>better wetting or penetration but contains other components if not rinsed
> >>>>that can be detrimental to the electrical performance of the assembly. The
> >>>>obvious advantage of the saponifier is that it will remove other
> >>>>contaminates on the PCA besides the flux that are not water soluble.>
> >>>>
> >>>>With that said we do use a saponifier but have very good process control on
> >>>>the types and angles of our spray nozzles in wash and rinse. Along with
> >>>>increasing temperature through the various rinse stages to facilitate the
> >>>>complete flushing and removal of the saponifier.
> >>>>
> >>>>Just a clarification as sometimes these two terms saponifier and surfactant
> >>>>are used interchangeably.
> >>>>
> >>>>
> >>>>Regards
> >>>>
> >>>>Michael Barmuta
> >>>>
> >>>>Staff Engineer
> >>>>
> >>>>Fluke Corp.
> >>>>
> >>>>Everett WA
> >>>>
> >>>>425-446-6076
> >>>>
> >>>>-----Original Message-----
> >>>>From: Graham Naisbitt [mailto:[log in to unmask]]
> >>>>Sent: Tuesday, May 04, 2004 5:41 AM
> >>>>To: [log in to unmask]
> >>>>Subject: Re: [TN] OA / RMA
> >>>>
> >>>>
> >>>>I must be mad sending this to challenge The Oracle himself but....
> >>>>
> >>>>The real beauty of the OA process is that it required only water - as
> >>>>distinct from Aqueous Process where Water Soluble, or some would say Water
> >>>>Washable fluxes were used that required some cleaning chemistry.
> >>>>
> >>>>Aqueous processes I always thought of as a misnomer and that it should be
> >>>>called Semi-Aqueous - ergo water only v water plus chemistry.
> >>>>
> >>>>However, the drawback with the Water Only approach is that it proved to be
> >>>>inadequate for some of the newer low stand-off devices such as micro-BGA,
> >>>>flip-chip and some of the smaller discreets <0604. Saponification had to
> >>>>added in order, not only to get under such devices but, more importantly, to
> >>>>get the darned stuff out from underneath including the "dissolved"
> >>>>contaminants.
> >>>>
> >>>>IMHO - Graham Naisbitt
> >>>>
> >>>>
> >>>>
> >>>>>I installed the first OA (misnomer, WS is better) full scale
> >>>>>wave-soldering production line in Switzerland (if not in Europe) as long
> >>>>>ago as 1965. The company in question is still using it,four soldering
> >>>>>machines later. I have since aided in many others, throughout the world.
> >>>>>Advantages of WS:
> >>>>>- better quality soldering with fewer rejects
> >>>>>- more tolerant of poorly solderable components
> >>>>>- widest operating window
> >>>>>- no expensive cleaning products
> >>>>>- minimal pollution from overall process
> >>>>>- lowest production costs
> >>>>>Disadvantages:
> >>>>>- requires good process control
> >>>>>- unforgiving of errors
> >>>>>- good quality cleaning equipment rarer than you think
> >>>>>- flux itself is fairly corrosive
> >>>>>Summary:
> >>>>>- requires a serious approach and qualification
> >>>>>- with this proviso, this is the way to go.
> >>>>>
> >>>>>Brian
> >>>>>
> >>>>>Dehoyos, Ramon wrote:
> >>>>>
> >>>>>
> >>>>>> Hi Technetters:
> >>>>>> Has anybody done a comparison study of RMA/OA fluxes for
> >>>>>>wavesolder? Or any personal experiences in this regard will be
> >>>>
> >>>>appreciated.
> >>>>
> >>>>
> >>>>>> Thanks in Advance
> >>>>>> Ramon
> >>>>>>
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