[volt-nuts] Best cleaning procedure for precision cirquits

Alan Scrimgeour scrimgap at blueyonder.co.uk
Sun Sep 26 06:50:21 UTC 2010


The precision instrument production line where I used to work used old style 
fluorocarbon solvent. The cold boards are lowered into vapour above a 
boiling tank of solvent so they are washed with pure condensing solvent. The 
tank has a water cooled collar to prevent excessive loss of solvent to the 
atmosphere. The room has a very powerful extraction system to keep vapour 
levels safe to breath. After a while the boards heat up and no further 
condensation takes place so the boards are removed and allowed to cool. The 
process is repeated several times. The tank has a secondary smaller 
compartment which is also heated but doesn't receive the distillate from the 
condensing collar. All the solvent from the main tank is transferred to this 
secondary tank by hand occasionally to repurify the main tank solvent. The 
result is that flux and other crud collects in the secondary tank and boards 
are washed only in self condensed very pure solvent with a minimum of impure 
spray (from boiling bubbles) mixed in. This was found to be essential for 
instrument to give the highest accuracy. Presumably that was down to leakage 
at op amp inputs. Less polluting water based board cleaners where tried but 
the boards took ages to stabalise afterwards even if baked in ovens.
I don't know if such care is necessary for a reference, but I'd choose to 
use it anyway if I could.

Alan





----- Original Message ----- 
From: "J. Forster" <jfor at quik.com>
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Sent: Sunday, September 26, 2010 5:09 AM
Subject: Re: [volt-nuts] Best cleaning procedure for precision cirquits


> Alpha also sold a "saponifier" used with hot water, Alpha 2001, which
> removed rosin very well.
>
> I did not mention it because it's an industrial chemical and comes in 5
> gallon pails.
>
> -John
>
> ===========
>
>
>> By far the most effective board cleaner I ever used was Alpha 564. I
>> remember back in the eighties Alpha 564 was used by major PCB
>> manufacturers as part of their solder bath assembly line processes - the
>> boards were automatically skimmed across a Alpha 564 bath after they were
>> skimmed across the solder bath. The Alpha 564 bath removed all resin,
>> leaving the boards looking factory perfect and new. However I was always
>> aware that Alpha 564 is a hazardous chemical. (So you must be careful not
>> to get it on your hands, nor breath the fumes, nor dispose of it
>> improperly in the environment.)
>>
>> I did find that the Solder Connection, in the UK, still sells Alpha 564:
>> http://www.solderconnection.com/prod_detail.php?product_id=39&PHPSESSID=a8b961ca4cab940fd51e1a1875fe2ce0
>>
>> Although Alpha 564 does a great job of cleaning boards, the more I read
>> about its composition, for safety and health reasons I unfortunately
>> cannot recommend it to most of us in this group. ...just too hazardous to
>> use...
>>
>> See:
>> Tetrachloroethylene Hazardous Substance Fact Sheet (New Jersey Dept. of
>> Health & Senior Services)
>> http://www.newjersey.gov/health/eoh/rtkweb/documents/fs/1810.pdf
>>
>> Alpha 564 datasheet and Safety are at:
>> http://www.solderconnection.com/specsheets/21427.pdf
>>
>>
>> Current Alpha Board Cleaners are listed at:
>> http://alpha.cooksonelectronics.com/products/cleaners/alpha-cleaners.asp
>> Maybe some of them are highly effective? Anybody in this group familiar
>> with any of them?
>>
>> Greg
>>
>>
>>
>> ----- Original Message -----
>> From: "Andreas Jahn" <Andreas_-_Jahn at t-online.de>
>> To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
>> Sent: Saturday, September 25, 2010 4:03 PM
>> Subject: [volt-nuts] Best cleaning procedure for precision cirquits
>>
>>
>> Hello all,
>>
>> currently I am soldering my first LTZ1000A reference board.
>>
>> Up to now I am cleaning my precision boards after soldering with
>> denatured alcohol in a pre-washing and a main washing procedure.
>>
>> After this the last washing stage is with clean water to get rid of the
>> white haze from the denatured alcohol.
>>
>> What is the best cleaning procedure?
>> Is there one in a repair manual of any precision instrument?
>> Which of the near best procedure can be done at a home?
>> What are You doing to clean the boards?
>>
>> best regards
>>
>> Andreas
>>
>>
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>
>
>
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