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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>>>>
>>>>
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>>>>
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>>>>
>>>>
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>>>>
>>>>
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>>
>
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