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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