Bicarb would not only be useless, it would be worse than useless. It is
true that it would "kill" the acidity in the residues, but it would
convert any soluble metal salts produced by the flux action into
insoluble carbonates, which would not be removed by the cleaning process
and some would inevitably remain on the assemblies. These could initiate
dendrite formation or a number of other nasties resulting in functional
failures. Don't even try it.
Easy demo: take a test tube. Put in a small amount of cupric chloride
(CuCl2) and add some water. Shake and you will get a transparent
greenish solution. Now add an equally small amount of bicarb, shake it
up, leave it still for an hour or two and tell me what happens and why
it has happened.
I don't recommend habitual use of bicarb for your stomach, either, no
matter how bad the canteen meals are or how heated the discussions with
your colleagues. God installed a pH meter in your tum-tums and this
causes the secretion of gastric juices, notably hydrochloric acid, to
maintain the appropriate acidity. If you add bicarb, your pH meter will
go berserk and pump in more and more HCl. The result could be a gastric
ulcer, in time. Will cause more harm than good. Much better: force
yourself to relax and let nature look after you in peace and quiet.
Ciao
Brian
Ivanoe Pedruzzi wrote:
> *This message was transferred with a trial version of CommuniGate(r) Pro*
> Hello Brian,
>
> just a little introduction. I'm not chemist, neither am I a scientist,
> just a plain electronic manufacturing engineer.
>
> I have always followed your e-mails with interess starting from the
> discussion on ultrasonic cleaning and cleaners. I remember reading that
> you designed and patented many cleaners for electronic assemblies. This
> is why I would like to share with you my thought.
>
> As for the neutralizer you mentioned in the attached e-mail, I
> understand that this has to be alkaline to compensate for the acid in
> the flux.
> On the same principle do the anti-acids for human body act. For
> istance, the sodium bicarbonate that I'm so addicted to get reliefs
> from long lasting discussions on the job, or bad cafeteria meals. :-)
>
> Do you think this might me used in conjuction with DI water to aim to
> the same effects of the brand name products you mentioned?
>
> It was just a thought.
>
> My best regards, Ivan
>
>
>
> Il giorno 19/gen/06, alle ore 09:50, Brian Ellis ha scritto:
>
>> *This message was transferred with a trial version of CommuniGate (r)
>> Pro*
>> As a general rule, water-soluble flux residues are very dangerous. They
>> are usually very acid and can attack metals on the assembly. At the best
>> they will make the solder joints matt. At the worst, increasing quantity
>> of the residues will form adsorption bonds with the substrate and
>> components within the residues may polymerise, making it
>> quasi-impossible to clean the residues after, say, an hour or so. It
>> therefore is **very** necessary that cleaning be started within minutes
>> of soldering. However, there is an excellent work-around that has been
>> proven and that can extend the hold time before cleaning to a few hours,
>> the use of a chelating neutraliser. Many flux manufacturers offer these
>> under trade names such as Neutralizer 2051, Rinse-Aid and so on. They
>> are mildly alkaline, buffered, room-temperature, dilute baths (pH
>> typically 8.5 to 9), which must NOT be confused with saponifiers, which
>> are unsuitable for this job. They serve many functions, but the
>> assemblies can stay therein, immediately after soldering/reflow, from 2
>> minutes up to, say, 4+ hours. They will actually improve the cleaning
>> quality at almost no cost. The assemblies should be cleaned within
>> minutes of their removal from the holding tank. The makers usually
>> recommend a 5% solution of the concentrate, but a 2% solution has been
>> proved equally effective.
>>
>> You can see this technique being used on the old video at
>> http://www.protonique.com/video/ in the context of wave soldering.
>>
>> Brian
>>
>> Joel Mearig wrote:
>>
>>> I am currently using a water-soluble, lead-free solder paste from
>>> Kester. I
>>> am trying to minimize the cleaning cycles so I leave flux on the
>>> product for
>>> an extended period of time. Do any of you have any recommendations
>>> on the
>>> amount of time flux can be left on the product without affecting the
>>> cleaning process? Thanks in advance for your input.
>>>
>>>
>>>
>>> Joel Mearig
>>>
>>> Delta Tau Data Systems, Inc.
>>>
>>>
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