[Diy_efi] info

Bill Shaw b.shaw
Mon Oct 31 14:24:26 UTC 2005 

But...but...but...  We're not talking about any of that.  We're talking
about a conformally coated PCB that got washed in antifreeze.  Convincing
people to do unnecessary stuff through 'scientific dissertation' isn't
necessarily a helpful thing. The simplest solution is frequently the better,
again MHO.

Moot point now since John merely blew it off and it is running again. :-)

Bill

> From: "Mike" <niche at iinet.net.au>
> 
> At 09:49 PM 10/31/05, you wrote:
>> I've 25 years in electronics myself, Mike.  Washed many circuit boards in
>> water with no issues.  Add on that the fact that this particular board is
>> conformally coated and a rinse in water becomes a non-issue as long as it is
>> dried promptly.
> 
> Sure no problem - that is *your* experience within your expectations
> and based upon your acceptable level of delivery. I am only prepared to
> wait 5mins before packing pallets of boards in antistatic, dry and clean with
> no
> chance of deposits, perhaps you are prepared to wait rather longer or
> mess about loading and unloading an oven instead of basic overhead
> infra red lamps, time is money - even in pilot production of a few hundred
> boards at a time.
> 
> Incidentally the price of true distilled water is comparable to the price
> of Isopropanol and some component manufacturers recommend the
> latter explicitly.
> 
> My experience is that water causes problems in fine level analog
> circuitry and that Isopropanol is the solvent designed to be used on the vast
> majority of components and circuit boards, hybrids, integrated circuits etc.
> 
> Eg. If you have designed a fuel cell amplifier with a 40nA per ppm resolution
> then you might change your mind or rather be happy to subsidise several
> pilot production runs and alter your design layout so designs are not so
> critical to board clearances where mineralisation might be an issue...
> 
> It would also be clear that one type of design is more or less
> susceptible than another, digital designs are rather more robust to
> mineralisation deposits, analog rather less so. Many boards are not
> conformally coated and we didnt know in advance if the posters was.
> 
> General rule I consider is rationalise behind industry leaders at
> the point in the market that has the greater return index for the
> complexity of the product. ie. Understand their reasons and their
> expectations in context with that which the client expects.
> 
> If you are into pilot production with the lowest rate of return on
> analog circuitry then Isopropanol is the recommended solvent
> by the component manufacturers, dries the fastest, leaves no
> mineralisation deposits and is comparable to cost of true distilled water.
> 
> .
> 
> I'm going back to finding a way to pump oil into my pump backwards
> so the darn thing can get primed without taking the thing apart <sigh>
> 
> Rgds
> 
> Mike
> 
> 
> 
> 
> 
>> Bill  
>> 
>>> From: "Mike" <niche at iinet.net.au>
>>> 
>>> At 08:33 PM 10/31/05, you wrote:
>>>> We're talking about rinsing the board in water,  not putting it in a bath
>>>> for a month.  Sheesh,  it's a shame how this list has deveolved into
>>>> endless
>>>> pissing contests and hair splitting. Back in the old days before the DIY-WB
>>>> fiasco made the list implode there was real, serious efi content here.  Now
>>>> it's just mostly this kind of junk.
>>> 
>>> I'm sorry Bill,
>>> 
>>> I was only intending to bring factual content and made no personal
>>> references - unlike others on this group, hope you were not sensitised by
>>> earlier emails, read on.
>>> 
>>> Water can get into all sorts of tiny places and cause electrolytic
>>> conduction,
>>> such as analog circuits where even a slight change in resistance from
>>> built up deposits from even a few minutes of electrolysis can affect long
>>> term stability. Bill,  I was uncritically warning against using water, and
>>> didnt intend to offend you... I'm not A.W  <chuckle>
>>> 
>>> Case in point, the analog parts of EFI inputs such as log to linear dont
>>> need much change in resistance to cause drift or offset errors - even a
>>> little bit of water in the wrong places even for a few minutes can cause
>>> offset errors which are enough to make a board unusable for hours or
>>> until its properly flushed with Isopropanol. Fortunately the board the
>>> poster was referring to is nicely coated, some arent...
>>> 
>>> Please accept Bill, that other posters have specific experience of
>>> troublesome issues. In my particular experience as an engineer
>>> of some 23 years experience, water is the worst thing to use in or near
>>> any analog circuits for even a few minutes. In one example a CO sensor
>>> board that had a high gain stage and 40nA sensr current was affected
>>> by the moisture from a finger smear and a wipe with a damp towel
>>> only made matters worse and even after drying it didnt improve.
>>> 
>>> The other assumption is that water is clean, sorry it aint. Tap water
>>> is full of minerals, they get deposited when they dry and can leave
>>> traces to affect analog circuits, that only takes a few minutes not months !
>>> And if you are prompted to get distilled then why not get Isopropanol
>>> and do the job properly, it is electronics.
>>> 
>>> Isopropanol has no minerals and is the solvent of choice for cleaning
>>> boards, follow the industry lead and avoid water - well <cough> unless its
>>> really distilled (not demineralised), used for as short a period as possible
>>> and board dried in an oven immediately thereafter...
>>> 
>>> Its a cute way too look at solvents by distinghuishing them as
>>> aggressive or otherwise, again I'm trying to be factual without making
>>> any criticism - I never made any personal indictment, I wanted
>>> to be clear its really an interpretation of a chemical compatibility issue
>>> and sure you are welcome to interpret your view of a solvent as
>>> aggressive or passive - frankly, I am incapable of seeing it that way.
>>> 
>>> No pissing contest Bill, facts presented without personal
>>> criticism and from a wealth of industrial experience in recognition
>>> of chemical compatibility issues...
>>> 
>>> Rgds
>>> 
>>> Mike
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> Bill
>>>> 
>>>>> From: "Mike" <niche at iinet.net.au>
>>>>> Reply-To: diy_efi at diy-efi.org
>>>>> Date: Mon, 31 Oct 2005 12:02:03 +0800
>>>>> To: diy_efi at diy-efi.org
>>>>> Subject: Re: [Diy_efi] info
>>>>> 
>>>>> At 05:13 AM 10/31/05, you wrote:
>>>>>> Actually,  they call water the 'universal solvent' for a reason.  I'd
>>>>>> start
>>>>>> there,  and if it appears there is some residue the water can't get I
>>>>>> might
>>>>>> try more agressive solvents.
>>>>> 
>>>>> mmmm, not really - Water is a fairly good ionic solvent but suffers
>>>>> from the H to OH equilibria, in that its neutrality is probabilisitc,
>>>>> when it gets to actually dissolve anything and is either acidic or caustic
>>>>> as a consequence and has repercussions on that basis. Vis a vis
>>>>> using water as engine coolant where electrolytic damage is so prevalent,
>>>>> the H to OH equilibrium seems to win out regardless of what chemicals
>>>>> are added. That green inhibitor needs frequent changing, what I've
>>>>> settled on is a tannin type pill which coats the alloy with a protective
>>>>> layer and seems to work effectively for long periods. The only downside
>>>>> is a little brown sludge if instructions/amounts not precisely adhered to.
>>>>> 
>>>>> Electronic components are not generally designed for immersion
>>>>> in water, sure some can tolerate water for cleaning - but for electronics
>>>>> Isopropanol is more generally accepted as the universal cleaner
>>>>> and might be interpreted as the universal solvent for pollutants
>>>>> affecting electronic repair and service. Its also ionic and boards
>>>>> shouldnt be left in it for long otherwise there electrolytic effects.
>>>>> The good thing about it is - its so volatile and drys off in a few
>>>>> mere seconds on some occasions, plenty of ventilation is essential
>>>>> as it is combustible and although it smells (ok) I wouldnt breath
>>>>> the stuff at all if I could help it.
>>>>> 
>>>>> Interesting your comment re "aggressive" bringing a human emotive
>>>>> issue to one of chemical compatibility. What I mean to say is there
>>>>> are so many products and processes that have only a compatibility
>>>>> issue not one which is either passive or aggressive
>>>>> and to use those terms seems discontinuous with solvents. Sure,
>>>>> the appearance is either one is more or less aggressive than another
>>>>> but it comes down to a sheer compatibility only in the long run.
>>>>> 
>>>>> Also water is (AFAIK) only ionic whereas Isopropanol is ionic and
>>>>> covalent in terms of its capacity to dissolve most pollutants which
>>>>> can affect electronics, the Isopropanol is designed around for that
>>>>> purpose.
>>>>> 
>>>>> Rgds
>>>>> 
>>>>> Mike
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>>> Again,  just mho.
>>>>>> 
>>>>>> Bill
>>>>>> 
>>>>>>> From: "Mike" <niche at iinet.net.au>
>>>>>>> 
>>>>>>> At 08:31 AM 10/29/05, you wrote:
>>>>>>>> I'd remove it from the case,  wash down the PCB and case good with
>>>>>>>> clear
>>>>>>>> clean water,  then blow it with compressed air and let it dry for a few
>>>>>>>> days.
>>>>>>>> Once I was sure it was complete dry I'd reassemble it and try running
>>>>>>>> it.
>>>>>>>> What id there to loose?
>>>>>>> 
>>>>>>> Best solvent to remove other things is Isopropyl alcohol (Isopropanol),
>>>>>>> let dry normally - dont use compressed air, there is potential for
>>>>>>> localised
>>>>>>> static damage,
>>>>>>> 
>>>>>>> Rgds
>>>>>>> 
>>>>>>> Mike
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>> Just MHO :-)
>>>>>>>> 
>>>>>>>> Bill
>>>>>>>> 
>>>>>>>> From: "Lee M. Lemoine" <llemoine at gmail.com>
>>>>>>>> 
>>>>>>>>> John, if antifreeze can damage paint, think about
>>>>>>>>> what it may do
>>>>>>>>> to a PCB.
>>>>>>>>> You could spend a lot of time replacing parts, and
>>>>>>>>> still have an
>>>>>>>>> unreliable
>>>>>>>>> ECU. Wrecking yard option sounds good. Make sure it
>>>>>>>>> comes from a
>>>>>>>>> car
>>>>>>>>> without a leaky heater core.
>>>>>>>>> 
>>>>>>>>> Geoff H
>>>>>>>> 
>>>>>>>>> 
>>>>>>>> _______________________________________________
>>>>>>>> Diy_efi mailing list
>>>>>>>> Diy_efi at diy-efi.org
>>>>>>>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>>>>> 
>>>>>>> 
>>>>>>> Regards from
>>>>>>> 
>>>>>>> 
>>>>>>> Mike
>>>>>>> Perth, Western Australia
>>>>>>> VL Commodore Fuse Rail that wont warp or melt !
>>>>>>> Twin tyres for most sedans, trikes and motorcycle sidecars
>>>>>>> http://niche.iinet.net.au
>>>>>>> _______________________________________________
>>>>>>> Diy_efi mailing list
>>>>>>> Diy_efi at diy-efi.org
>>>>>>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>>>> 
>>>>>> _______________________________________________
>>>>>> Diy_efi mailing list
>>>>>> Diy_efi at diy-efi.org
>>>>>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>>> 
>>>>> 
>>>>> Regards from
>>>>> 
>>>>> 
>>>>> Mike
>>>>> Perth, Western Australia
>>>>> VL Commodore Fuse Rail that wont warp or melt !
>>>>> Twin tyres for most sedans, trikes and motorcycle sidecars
>>>>> http://niche.iinet.net.au
>>>>> _______________________________________________
>>>>> Diy_efi mailing list
>>>>> Diy_efi at diy-efi.org
>>>>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>> 
>>>> _______________________________________________
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>>>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>> 
>>> 
>>> Regards from
>>> 
>>> 
>>> Mike
>>> Perth, Western Australia
>>> VL Commodore Fuse Rail that wont warp or melt !
>>> Twin tyres for most sedans, trikes and motorcycle sidecars
>>> http://niche.iinet.net.au
>>> _______________________________________________
>>> Diy_efi mailing list
>>> Diy_efi at diy-efi.org
>>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>> 
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>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
> 
> 
> Regards from
> 
> 
> Mike
> Perth, Western Australia
> VL Commodore Fuse Rail that wont warp or melt !
> Twin tyres for most sedans, trikes and motorcycle sidecars
> http://niche.iinet.net.au
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/diy_efi

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