phil@diablo.amd.com (02/18/89)
We buy these spray cans of TCE for defluxing circuit boards. I
know that fluorocarbons are bad for the ozone layer and in this
case, we're not just talking about the propellant, but the contents
delivered by the propellant are fluorocarbons (I believe).
What alternative do we have? We really need to be able to clean
the circuit boards after reworking them so we can visually inspect
them and also to remove any small pieces of solder.
--
Phil Ngai, phil@diablo.amd.com {uunet,decwrl,ucbvax}!amdcad!phil
"In Texas, they run the red light after it turns red."
"In Taiwan, they run the red light before it turns green."jonb@hpcupt1.HP.COM (Jon Bayh) (02/19/89)
> We buy these spray cans of TCE for defluxing circuit boards. I > know that fluorocarbons are bad for the ozone layer and in this > case, we're not just talking about the propellant, but the contents > delivered by the propellant are fluorocarbons (I believe). > > What alternative do we have? We really need to be able to clean > the circuit boards after reworking them so we can visually inspect > them and also to remove any small pieces of solder. > > Phil Ngai, phil@diablo.amd.com {uunet,decwrl,ucbvax}!amdcad!phil Denatured alcohol seems to work well for individual jobs. Just brush it on with a paint brush and let it drain off. I don't know how well it would work in a production application. I also don't know whether it would harm (or alter the specs of) components. I've used it a few times and had no problems. Jon Bayh hplabs!hpda!jonb
henry@utzoo.uucp (Henry Spencer) (02/19/89)
In article <24497@amdcad.AMD.COM> phil@diablo.amd.com () writes: >We buy these spray cans of TCE for defluxing circuit boards. I >know that fluorocarbons are bad for the ozone layer and in this >case, we're not just talking about the propellant, but the contents >delivered by the propellant are fluorocarbons (I believe). > >What alternative do we have? ... My impression is that at the moment, the answer is "none". In many applications of halocarbons (fluorocarbons etc.), they have been chosen for the job more for convenience than because there aren't any viable alternatives. Electronics cleaning is one of the exceptions, though, where good substitutes are very difficult to find. There is work in progress on finding variants that will do the job but won't be as harmful (the potential for ozone-layer damage varies enormously among even fairly similar compounds), but it hasn't reached the stage of marketable products yet. -- The Earth is our mother; | Henry Spencer at U of Toronto Zoology our nine months are up. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
mmm@cup.portal.com (Mark Robert Thorson) (02/19/89)
Kester offers solder with water-soluble flux. I've used this stuff, and it does solve the defluxing problem. But for my own personal use, I use rosin core and don't bother to clean the flux off. I don't use water-soluble because the flux has a slightly evil smell, and I don't know what's in it. Rosin is fairly pure, from pine trees, and seems harmless. And people have been using it as a flux for over 100 years, so I can be confident it's safe.
R_Tim_Coslet@cup.portal.com (02/20/89)
The biggest problem with most of the alternatives to "CFC solvents" is
that they tend to be FLAMABLE! This produces significant problems in storage
and use that "CFC solvents" don't have.
Just imagine having a rework person scrubing a board with an Alcohol,
Acetone, or Hydrocarbon based solvent... vapors drift down the bench and
find an ignition source..... .... ... .. .
I am sure suitable substitutes will be found... but they will probably
be more expensive (at least at first) and will undoubtedly have their
own unique problems.
R. Tim Coslet
Usenet: R_Tim_Coslet@cup.portal.com
BIX: r.tim_coslet
P.S. I have heard that some companies have started introducing "environmental"
blends of different "CFC solvents" that they think don't do as much damage,
but they are still CFC's.sparks@corpane.UUCP (John Sparks) (02/21/89)
In article <1989Feb18.234109.3779@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: > In article <24497@amdcad.AMD.COM> phil@diablo.amd.com () writes: > >We buy these spray cans of TCE for defluxing circuit boards. I > >know that fluorocarbons are bad for the ozone layer and in this > >case, we're not just talking about the propellant, but the contents > >delivered by the propellant are fluorocarbons (I believe). > > > >What alternative do we have? ... > > My impression is that at the moment, the answer is "none". In many > applications of halocarbons (fluorocarbons etc.), they have been chosen > for the job more for convenience than because there aren't any viable > alternatives. Electronics cleaning is one of the exceptions, though, > where good substitutes are very difficult to find. > > There is work in progress on finding variants that will do the job but > won't be as harmful (the potential for ozone-layer damage varies enormously > among even fairly similar compounds), but it hasn't reached the stage of > marketable products yet. > -- > The Earth is our mother; | Henry Spencer at U of Toronto Zoology For your application (small number of boards, hand soldered and cleaned) your are correct. I know of no alternative to using the spray flourocarbon. But for large batches of circuit board cleaning there is much reaserch going on to reduce flourocarbon output into the atmosphere. Here at Corpane, our major business is vapor degreasers, circuit board cleaning machines, and vapor phase soldering machines. One of our companies unique features is the method we use to pratically eliminate any flourocarbons from escaping (not 100% , but at least 1/4 of any of our competitors) We use a variable heat refrigeration system to heat the solvents, which creates a vapor blanket over the liquid solvent. The cold side of the refrigeration system condenses the vapor back into a liquid to be reused. The physical layout of our system keeps most of the vapor from escaping into the atmosphere. We are also looking into alternative technologies, such as water based resins on surface mount (vapor phase) boards. This would allow the resin to be removed from the boards with a water based cleaner. However, this raises it's own problems, such as water pollution from the resin. It's a tricky area. disclaimer: This is MY opionion. not corpanes. -- John Sparks // Amiga | {rutgers|uunet}!ukma!corpane!sparks \X/ UUCP | >> call D.I.S.K. @ 502/968-5401 thru 5406 << As far as we know, our computer has never had an undetected error.
henry@utzoo.uucp (Henry Spencer) (02/22/89)
In article <14859@cup.portal.com> R_Tim_Coslet@cup.portal.com writes: >P.S. I have heard that some companies have started introducing "environmental" >blends of different "CFC solvents" that they think don't do as much damage, >but they are still CFC's. And all CFCs are evil? Sorry, wrong. It really is true that some are much more harmful to the ozone layer than others (or at least this is currently thought to be true). Now, whether those companies are telling you the truth about their products, *that* is a different question... -- The Earth is our mother; | Henry Spencer at U of Toronto Zoology our nine months are up. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
hd@kappa.rice.edu (Hubert D.) (02/24/89)
This is a problem. The cleaning of large areas of PC board real estate is best done with fluorocarbons. However, plain old isopropal alchohol will work fine if you don't mind doing a little scrubing. We design and build oneses and twosies so the scrubbing is not too laborious. The best scrubber is an acid brush which has been cut down to 1/2 inch of bristles (they come with an inch of bristles). The acid brush is a very cheap item available at any plumbing supply store for about a nickel apiece. They are made to be used for applying flux to copper pipe before soldiering. Hubert Daugherty hd@rice