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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