At 07:30 -0700 7/22/09, trag wrote: >On Jul 21, 3:02 pm, Aaron Parker <[email protected]> wrote: >> Any tips for thoroughly cleaning the mainboard of some of these older >> devices? I've got an Apple II Plus and two Apple IIe's that were not well >> cared for (yet still power on) that I'd like to clean up. > >The boards can be cleaned with a number of solvents. If you still >have a shop in town that sells electronics supplies you might check >there for a can of flux remover or flux cleaner. This will remove >pretty much any kind of crud from your board. You'll want to use it >outside, as flux remover tends to include things like toluene and >MEK. > >Other acceptable solvents are isopropyl (rubbing) alcohol, provided it >does not contain any skin lotions, so the only ingredient besides >alcohol should be water. Our local grocery sells a 91% solution. >Home Depot sells a one gallon can of denatured alcohol which would >work, but that's probably a bit more than you'll ever need. > >Finally, for the last rinse distilled water is a good choice. > >Or you can run it through the dish washer with no detergent and no dry >cycle...
Until the European RoHS rules changed the composition of solder around 2000 AD there were well established solvents and flux cleaners that were specifically listed and known to circuit board and component designers. Toluene and Methyl-ethyl ketone were never on that list. Nor was acetone which is methyl-methyl ketone and removes nail polish. Isopropyl and ethyl alcohol were specifically approved. Trichloro ethylene was but is now considered carcinogenic as is Toluene which is two benzene rings tied to each other. Clean water has always been allowed. De-ionized water which is quite corrosive and difficult to use was approved. The various plastics on boards were all carefully chosen to be resistant to the alcohols. You will not dissolve the memory sockets or the plastic casing of transistors with either of them. Initial assembly of the circuit boards consists of raising the temperature of the board almost to the melting point of solder and then flashing for a couple of seconds to a bit over 200 centigrade for surface mount or passing over a wave of molten solder for through hole stuff that was used in the Apple II era. After soldering with tin-lead solder the board was washed. Ultrasonic in a tricloroethylene bath was neat but poisonous. It was replaced by water-based dishwasher technology though alcohol was good at removing the resin flux used for tin-lead solder. Boiling water temperatures are nothing compared to the soldering temperature. But there is a rub that cannot be ignored: >>>> There may have been special components that contained plastics or had heat >>>> sensitive properties that were placed on the board by hand after the >>>> cleaning.! <<<< Water is always OK. It's cleaning the water up that's the problem. You mustn't leave residue that can interfere with connectors. A rinse with distilled water before drying can help. You can also remove water with a dip in alcohol which will absorb the water so you can shake off the mixture. But the alcohol needs to be dry - meaning not the rubbing alcohol which can be 50 % water. For completeness, but not the OP's problem, RoHS means tin-lead solder is not allowed and resin flux no longer works. Soldering temperatures are higher and acid flux is used. High temperature washing with proprietary flux removers is needed to prevent later corrosion. That all means the washing rules for modern stuff are different. Flux-cleaner for that kind of solder is quite different than what you would use for the tin-lead on an Apple II. Personally I use gallon jugs of isopropanol that I get from a commercial cleaning establishment. It's advertised as "dry absolute" meaning no water at all but that's a lie. After you open the container the alcohol absorbs water from the air so it doesn't stay really dry but's it's a lot better than rubbing alcohol. I worry about denatured alcohol. It has additives to make it poisonous so you won't drink it but you can never find out what the denaturants are. Might they affect the circuit board? Methanol was once added but that makes you blind and I suspect the lawyers don't approve of that anymore. -- --> From the U S of A, the only socialist country that refuses to admit it. <-- --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
