SNIP
OK thanks. This system has a few minuses. First is the cost - a smallish trial is about $100, with surface treatment and shipping.
They are re-selling Dow Corning, I bet, so it would be worth checking with DC about their 2 parts.
$500 a gallon is more than I want to pay, but it goes a long way.
Sure, I'll bite.
They're talking about glacial acetic acid at >80% concentration. Red and white vinegar is about 5% acetic acid. I would not recommend high concentration vinegar on your salad. I agree that acetone is really nasty stuff (nail polish remover). Whether it is more dangerous than glacial acetic acid depends on the concentration.
A previous employer had a "modular products" division which made DACS, A/D, amps, etc that were potted in plastic packages. Although not my job, I got involved in some of the experiments, including one where they tried potting a PCB in "high voltage" RTV that reeked of acetic acid. It failed an accelerated burn-in test almost immediately. I didn't see the post mortem, but I suspect that most of the copper traces were rotted out.
Of course, conformal coating is very different from encapsulation in that it allows for a large surface area and rapid solvent and curing agent evaporation.
Only if there's an easy exit path. The modules were roughly a rectangular prism, with a bottom cover that had a hole in it for pouring in the encapsulant. It wasn't big enough. The lack of an exit hole sometimes trapped air in the corners, which was another headache. Two holes, and filling under pressure, were later used to fix the problems. Where heat was a problem, silica sand was used, followed by an epoxy seal.
Like any volatile, vapor pressure determines the rate of evaporation. If you seal the package, it's going to remain there forever. However, this doesn't apply to your conformal coating, except in tight areas where the solvent might become trapped. That bit me with unsealed DIP switches, which tended to trap liquids and condensed vapors inside the switch. Also pots, connectors, and mechanical parts with built in cavities. We had to manually seal the switches with pink latex solder mask to protect the parts. You might have the same problem if your lamp has any such components.
Water is pervasive in the environment. It doesn't take much to condense water on PCB's. As I mentioned, I watched an RTV potted module fail in a few days during an accelerated life test. However, if you are planning to sell lots of replacement products, you could just use acetoxy silicone RTV, let the board rot, and make money on repeat sales of replacements (kinda like the bulging electrolytic capacitor plague).
We also use RTV to vibration proof VCO's and crystals. RTV was also used to waterproof areas of a PCB that might have leakage problems. Some exposed solder connections were also protected with RTV. "Electronics grade" was always used (except when purchasing screwed up).
I wasn't able to find the concentration of the acetic acid cure use in RTV. However, judging by the stench, I suspect that it's a far higher concentration than the 5% found in red/white vinegar or 3% in vinaigrette.
Yep. I managed to ruin a nice pair of pants during last summers "winterization" of the house, where RTV caulk was a major player. I used acetone to remove the RTV before it set, which just smeared it over a larger area. Don't ask why I was wearing good clothes for such a messy job.
Nope. See the original video comments at: 1) This silicone (GE Silicone II) does not outgas acetic acid (at least not much if at all). Most silicones I've dealt with that were purchased recently use other chemicals. I've been using this method for over a year and haven't had ANY issues with the chips functioning. The MSDS sheet at: shows that it uses as one of these as a curing agent. I'm not sure which one: DISTILLATES, PETROLEUM,HYDROTREATED 64742-47-8 1 - 5 % Hexamethyldisilazane 999-97-3 1 - 5 % Methyl trimethoxysilane 1185-55-3 1 - 5 % The stuff reeks from ammonia which comes from the breakdown of the hexamethyldisilazane, so I'll guess(tm) that it's the curing agent. The petroleum distillate turned out to be kerosene, probably to lower the viscosity so that it will flow. The methyl trimethoxysilane improved adhesion to glass.
My chemical education and experience is extremely spotty. Since many of the problems I've had to troubleshoot involve chemical processes, I've gained some experience in this area. I are not an expert.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Imagine opening a half-full bottle of white vinegar. Now, squeeze the bottle so that the air in the headspace puffs out. Finally... position your eyes / nostrils *directly over the bottle* and puff.
Cringing just thinking about it? Yeah, it's not pleasant stuff. ;-)
Best guess, vinegar should have a saturation vapor concentration of around
400 ppm at room temp.The potential concentration from curing silicone is considerably higher (~20,000 ppm), though you'll never see that in free air, or once the surface skins over and reaction becomes diffusion limited.
Reaction, by the way, is driven by moisture (hydration).
An aside, there's no such thing as AcCOOH (which would be acetylformic acid I guess, but if you could try to make it, it would simply lose a CO2 instantly); acetic could be written MeCOOH (Me = CH3 radical), but is most often AcH (Ac = CH3COO radical). :)
Yup, I've seen it before. Solder turns white, copper green.
Lead doesn't corrode much in a few acids (slowly in HCl, passivated in sulfuric), but its acetate is quite water soluble. (And bizarrely... tastes sweet.)
You get the added bonus that acetate forms a complex with copper (hence the green color), which is more soluble than non-complexed. Other examples of complexes include: oxalic acid to dissolve iron stains (ferric hydroxide is immensely insoluble, so much so that ferric chloride turns murky above a pH of 2 or so!), or citric acid to passivate stainless steel (related to iron and chrome oxides).
(Related trivia: aluminum is passive against concentrated sulfuric and nitric acids, but reacts instantly with HCl. Likewise, aluminum does not react with a copper sulfate solution, despite the electrochemical difference. Add just a dash of chloride, however...)
...Speaking of complexes, copper also forms an ammonia one. In fact, copper soaked in ammonia water (with exposure to air) oxidizes to a solution of extremely deep blue copper tetrammine hydroxide, Cu(NH3)4(OH)2.
As long as it stays shiny, you're fine, but it's worth noting that both the ammonia and acetic acid varieties can corrode copper. (Solder should be pretty good though, I don't think tin or lead form a complex.)
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
1) What was the question? 2) In the CONTEXT of the question, *and* CONTEXT of "military", what the hell would any one deduce? 3) Only an idiot would NOT think Moisture Fungus Proofing.
Use of acetic acid curing RTV guarantees its existence for YEARS. One *MIGHT* decrease the "lifetime" by use of a high vacuum for a year..
@@@@@ No they ain't. They are talking about an exposure level of 10-15 ppm. There is no mention of glacial. This states that the AcCooH (my notation should be obvious) - the AcCoOOH is toxic in small quantities, e.g. 10 ppm. This is sheer nonsense, and is the crying of girly-men. :) Red
They are talking about vapor in the air here, and AcCOOH is NON-TOXIC at their levels and indeed at any common concentration in the air.
It's typical to fear anything called "acid" for the chemistry illiterate. Also, government types hitch up their skirts and cry warning at nearly everything. The reason: "We're here to protect you. Do you feel safe? "
@@@ Nah. It's just not that kind of etchant.
@@@ Yes, that's not a conformal coating - should always use 2-part.
@@@ Yes, I'm just protecting an isolated connection to a 10W led. For potting, I wouldn't touch RTV with a 10 foot pole...But the video shows him doing it with acetic RTV.
@@@ That would be unethical, and my criminal days are behind me.
@@@ Me too. I've gone through some nice clothes - some with acetylene torch burns.
@@@ OK - Glad to know it. Ammonia another non-toxic chemical, by itself.
Most silicones I've dealt
@@@ I will try it - the solvent thinning might be useful.
@@@ Who is an expert these days? Do you tink the ammonia stuff better for general use?
XXXXX below
XXXXX I did put my nose directly over a bottle of vinegar and breathed deeply. I love the smell and find it quite refreshing. I enjoy taking some nice French bread or Cabiatta bread, pouring a half cup of balsamic vinegar, and soaking the bread in it. Delicious. :)
XXXXXX Remember Ralph Waldo Emerson - "A foolish consistency is the hobgoblin..."
True, you could write acetic acid as AcOOH, but that looks funny. The carboxylic acid group is -COOH, and the consistent way to write it is CH3COOH, but everyone knows what we are talking about here, and furthermore the focus is on the COOH, so I just write AcCOOH to emphasize that. As far as I know, Ac has no precise meaning.
The names in chemistry are imprecise as well: EGCG - EpiGalloCatechinGallate or OPC - oligoproanthocyanidins. The first is green tea OPC, and the second word is related to the first,. The OPC's are oligomers which are the most common organic chemical in plants after cellulose. They are the source of many anti-ocidant drugs that prevent and cure cancer, reverse aging, etc etc. They are likely to be used to cure cancer, heart disease, and alzheimers in the future. (hae a role in) I tested some plants in the jungles of Brazil for these compounds, and they are everywhere.
The plants use them to quench free radicals from the sunlight photons hitting the resonant chlorophyll structure. I flood myself with OPC's all the time.
XXXXX Yes, that's why kids in ghettos eat it. Also, the Romans ate it as a desert. :(
XXXXXX I have polishing machines for metals, and polish brass and SS. There are many black art formulas. Brown rice polishes SS. Whole wheat flour polishes SS also. I polish metals with vibratory, tumbler, and cement mixer. Media I have is gritted plastic, ceramic rods, SS rods, and ceramic triangles. Recently I had good luck using whole wheat macaroni coated with nufinish car polish. The WW curved noodle does not get into crevices, so is a good shape.
snip
You suggested that, not me. And I was correcting you, because you were wrong.
You should avoid using organic chemistry terms at all then; I just posted the precise meaning of the Ac radical. It is used very commonly in organic chemistry. There are further words related to it, like acetylation, where CH3COO- is stuck on to something (like adding AcCl -- acetyl chloride, CH3COCl, to phenol, C6H5OH, in nucleophilic aromatic substitution).
Hmm, minor correction, it has to be Ac = CH3CO-, in which case the acid is AcOH. That looks much better.
CH3COOCOOH is nonsense.
Common or descriptive names are imprecise. IUPAC compliant names are exact, since the structure is called out.
This is only applicable to given molecules, and not descriptive of a class of chemicals, such as your example. In that case, imprecision is the point. The structure can still be descriptive of a range or family (gallo-, catech-, anthrocyan-, and so on, are recognizable as various, naturally occuring, substituted aromatic compounds).
Another example: one cannot name polyethylene, as it is a mixture of many N-polyethylenes, occasionally with a stray radical, functional group or branch present (depending on manufacture, age, exposure and so on).
I can't say chemistry is all bells and whistles. Certainly, there's a lot you must know, because a lot is "stamp collecting", organizing chemicals by structure and naming them and remembering all the names.
And then there's the suffixes. Whoever had the grand idea to use these suffixes should've been shot: ethane (C2H6) ethene (= ethylene, C2H4) ethyne (= acetylene, C2H2) ethine (not a proper name I think, but would be ethylamine, C2H5NH2) ethanol (C2H5OH) ethanal (C2H4O) etc.
Er.. all of which have been shown harmful or ineffective. Turns out, cells are designed for oxidative stress. It's a cellular signal, and an energy source, and a punishment (e.g. neutrophils).
For example, the body develops cancer all the time. It's a natural thing. Most often, the genetic change lights up surface proteins, the immune system attacks it, and that's that. Or it doesn't develop the mutations to become aggressive, grows to a diffusion-limited size, then dies out (the unlucky ones which we have to deal with macroscopically are the ones that learn to grow blood vessels, among other things). Both reasons involve oxidative stress pretty importantly.
Oxidative stress may be indicated in mutations, but there are other mutation mechanisms which cannot be prevented at any concentration of antioxidant. Therefore, it would be more logical to expect antioxidants to increase ones' cancer risk!
There is literally not one thing that has been discovered in molecular biology that should be reported in the press, not with the crap quality of reporting as it is. Academic papers are barely enough, and that's from the researchers with decades of experience. Let alone the students and faculty who read them hastily. The systems are simply too complex, too many variables and reactions involved, to make a simple statement about something.
Does this sound familiar? "Coffee is bad!" "Coffee is good!" "Chocolate is bad!" "Chocolate is good!" I'll give you one guess as to why these completely and utterly exclusive headlines exist.
No, there is NOTHING* which will prevent or cure cancer, or aging, or improve intelligence. There are plenty of things which will worsen the latter. Which should be obvious from this already. But as far as things you can do with your body, the best you can hope for is good genes and an optimal input. Maximizing any one thing is guaranteed to make things worse.
*Well, one way is obvious: prevent anything in the body from reproducing (cellularly) at all. Anything that's not dead must be cancer, so we can kill that too. Of course, one does not live long if one is made of dead. If you could have continuous application of, say, stem cells designed to produce supporting structure then die quickly, you could live forever. This is the idea of, darned if I can remember his name, but he's had more than a few articles around, and even a TED talk. Obvious problem being, well, we don't know how to create and administer such a treatment. But that said, some point in the future, it's very likely the (biological, not cybernetic or computational) solution to eternal life will require daily regeneration treatments.Uh..??
That was a statement at least as idiotic as the corresponding symptom. I don't know where to begin.
Uh, this has nothing to do with formation of complexes. Those are just abrasives.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation (and armchair chemist) Website: http://seventransistorlabs.com
Actually because it's a reaction-diffusion thing, I wonder if a pressure steam treatment would help, then followed by gradual degassing to a high vacuum.
Elevated temperature and the presence of water aren't exactly helping the problem with regards to corrosion though. :P
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
I'm afraid its precise meaning is "actinium", so it would be actinium acetate, modulo stechiometry ;-P
Best regards, Piotr
Yes, outside of organic, the rarely seen Ac would be something, ah, a little hotter indeed. :)
Hmm, formate -- HCOO(-) actually.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
Probably Aubrey de Grey:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
That's the one! Thanks.
Tim
-- Seven Transistor Labs Electrical Engineering Consultation Website: http://seventransistorlabs.com
I will "shark-attack" your points, a bite at a time :) :
"You should avoid using organic chemistry terms at all then; I just posted the precise meaning of the Ac radical. It is used very commonly in organic chemistry."
Nonsense. Consider the widely-used name Proanthocyanidins. This is widely used by organic chemists. Where does that name come from? Well, if you boil the chemical in 1 N HCl, it turns blue. A good color indicator. Pro + antho + cyanidin = Gives + plant matter + blue color.
Are you going to tell all the organic chemists in the world they can't talk as they do because you know better? What is your experience in organic chemistry?
The problem with OPC's (proanthocyanidins) is that they can take literally thousands of forms, and yet they act alike as anti-oxidants and with the blue test.
Organic chemists widely use generic names whose meaning is clear. It's how you control complexity in conversation. If I say, "EtOH" to an organic chemist, he knows what I am talking about. Or steroids, alkaloids, terpenes, dienes, etc.
geez.
Tim:
Er.. all of which have been shown harmful or ineffective.
XXX Your statement is scientifically false, as they have not been shown to be ineffective. How could they be? People live too long. The truth is, it's an open book, and my language was a bit too definite, but I "lean in" to counter the misinformation out there.
You have been reading too many Big Pharma oriented papers. So what makes me say that OPC's can make you live longer? One piece of evidence is the French paradox. Red wine drinkers live absurdly longer than non-drinkers, particularly given they are acoholics.
That there is an perfect oxidant system in the body is nonsense. It gets out of whack, and anti-oxidants help restore it. There is a revolution in medical science now abut the potential for this.
Here is a large recent book on the subject: "Inflammation, Oxidative Stress and Cancer." ed. Ah-Ng Tony Kong. 2014
Tony is Chairman of the Pharmaceutical Sciences Department at Rutgers University. I have the book in front of me, and it has 607 pages of 32 chapters by solid scientific contributors from many big name medical schools and graduate schools.
It discusses results in breast cancer, lung cancer, etc. prevention and treatment.
Is this large army of scientists all wrong, as you say? I'd estimate there are
10,000 scientists working full-time in places like Harvard or Stanford in this field.They are doing this because of positive results.
This is a HOT field in medical science today, and I would suggest you keep an open mind. Which area of medical science are you in?
Check out this:-
Item of interest is at about 11:50 or so.
-- ******************************************************************** Paul E. Bennett IEng MIET..... Forth based HIDECS Consultancy............. Mob: +44 (0)7811-639972 Tel: +44 (0)1235-510979 Going Forth Safely ..... EBA. www.electric-boat-association.org.uk.. ********************************************************************
Thanks, but the video does not play outside the UK, it says. Can you describe what it says at 11:50 ?
Thanks in advance. jb odd BBC policy.
But your stuff is the best protype solution I found. I found a knock-off on ebat for much cheaper - "cell cure"
Tim Thanks. Since I started this quest, and talking with vendors, I have found out a few specifics.
Sylgard 184 is a 2 part conformal, clear, no UV indicator.
184 can be heat accelerated at 150 C to 10 minutes cure."Sylgard Primer Coat" can be used with it, and should.
RTV's can be temperature accelerated "mildly."
Sylgard 732 is a food grade RTV, no direct contact.
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Henkel - I plan to research them more thoroughly, at this point. The conformal coatings are under the "Loctite" brand, I think.
================
I also looked on ebay, and found conformal coatings there. One is called "cell cure." It is 30% of Dow Corning cost. May be worth a look, but who knows?
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