[Diy_efi] info
Mike
niche
Mon Oct 31 16:09:04 UTC 2005
At 11:34 PM 10/31/05, you wrote:
>Oh brother. Ok, I'll agree that some other people using some other
>materials and some other circuits have had problems with water. This
>particular conformally coated PCB , however, should have no problems with a
>water rinse and dry.
Ok sure, no problem - agree for the most part 'should' being the
operative adjective subject to a degree of long term uncertainty ;)
Rgds
Mike
Some people are so different, one might be inclined to derive
an expanded definition for the word 'different'.
<chuckle>
>Bill
>
>> From: "Mike" <niche at iinet.net.au>
>> Reply-To: diy_efi at diy-efi.org
>> Date: Mon, 31 Oct 2005 22:51:52 +0800
>> To: diy_efi at diy-efi.org
>> Subject: Re: [Diy_efi] info
>>
>> At 10:24 PM 10/31/05, you wrote:
>>> 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.
>>
>> Bill, please understand, we didnt know *at the time* it was conformally
>> coated.
>>
>> Water may be simple but it *does* cause problems - especially where
>> there are any number of analog circuits. Incidentally, Isopropanol is
>> also a pretty simple molecule IMHO ;)
>>
>> The simplest solution is to use the one which is the recommended
>> solvent - not the cheapest and easily accessible if you want the best
>> professional outcome longterm.
>>
>>> Moot point now since John merely blew it off and it is running again. :-)
>>
>> Well, with respect, we dont really know its moot because anyone with
>> even minor experience of electronics *knows* the first impression doesnt
>> mean lasting reliability and freedom from long term corrosion.
>>
>> ie. A board can look as nice cleaned with water as any other solvent.
>>
>> Eg.
>> We had a local PCB supplier some 12 years back, now bankrupt. He
>> produced process control alarm boards. Yes, he washed em in water
>> and I might add in an ultrasonic tank so he was sure water would get into
>> the nooks and cranies and not fully dry out before he coated them in
>> plain old varnish. The boards lasted 2 to 3 years before random failures.
>>
>> Suffice it to say, the varnish cracked in some places, the mineralisation
>> from the first lot of water left hygroscopic areas which conducted
>> along the varnish cracks, the boards failed. The company demanded the
>> replacement of all the varnished boards, through legal mechanisms they
>> drove the company bankrupt, the guy who bought the rights is an ex plumber,
>> thought he knew it all, didnt read any tech specs on electrolytic caps,
>> boards or even had trouble with the term 'hygroscopic"...
>>
>> Had they used the recommended solvent at the time - guess the outcome ?
>>
>> Bill, with electronics - it is necessary to use the recommended solvent.
>>
>> There is a responsibility in ensuring we are properly informed where others
>> rely on our expertise and not blind faith or hope that water is simple.
>>
>> It is fully appropriate to offer a dissertation based upon experience and
>> knowledge of chemical compatibility issues as there are others reading this.
>>
>> If your business is dependent on supplying boards in commercial
>> quantity and you expect to stay in business on that basis in the long
>> term using water from whatever source then I advise caution. If you
>> are not doing it as your primary income source, as perhaps a hobby where
>> you are still learning of long term effects, then you take your
>> risks and I hope you can connect the cause with the effect and are open
>> to learn from the experience of others to save you uncertainty,
>>
>> Cheers
>>
>> Mike
>>
>>
>>
>>
>>
>>
>>> 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
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> 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
>>>
>>> _______________________________________________
>>> 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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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
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