- reflowing BGA with a hot air gun? - 3 Updates
- How to unsolder silver solder from a component legs? - 4 Updates
- Will Deoxit on a circuit board cause problems? - 1 Update
| etpm@whidbey.com: Feb 08 08:09AM -0800 I have a laptop that is acting really weird. It's an older ASUS, probably ten or twelve years old. It was plugged in, closed, sitting on a table. It worked fine a few days before the problems started. The display keeps shaking. The machine takes forever to boot up. And then acts weird. But if I push down hard on the lower left side of the machine it works fine. As long as the pressure is kept up and in just the right area. I spoke to my son about this problem because he knows more about this kind of thing than I do. He said it sounded like a video card problem that he and some of his computer whiz friends have run into. Apparently the video processor can get too hot and the BGA under it can start to debond. He has a hot air rework tool and he said I might be able to reflow the chip. Is this something that a rank amateur can likely do? Eric |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Feb 08 11:15AM -0500 > He has a hot air rework tool and he said I might be able to reflow > the chip. Is this something that a rank amateur can likely do? > Eric Since the machine is on its way out anyway, why not give it a whirl? Do your backups first, of course. Laptops use the circuit board as a stressed structural element, so they sometimes crack when mistreated, e.g. when picked up horizontally by a front corner. I had one go like that, and the symptoms were similar to yours. Now when I need to one-hand a laptop I pick it up near the hinge instead. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| N_Cook <diverse@tcp.co.uk>: Feb 08 04:40PM > He has a hot air rework tool and he said I might be able to reflow > the chip. Is this something that a rank amateur can likely do? > Eric I'd try mechanically doing what your fingers were doing, with silicone rubber sleeving stretched/twisted appropriately, wooden wedges (ex-sprung clothes pegs) etc . Don't overdo the pressure, just enough to emulate the finger action. |
| M Philbrook <jamie_ka1lpa@charter.net>: Feb 07 05:49PM -0500 I have been trying to remove a rectifier modual from an AC inverter (Micro Master 440), for what ever reason, a very high temp solder was used, Silver Solder. MY solder rework station set at 900F just sits there on the solder blob without even making a dent into it. I have gotten a few legs usng wick and a large mass 120 watt iron. the iron just barely softens it and thus the wick really does not get it all. So today I put my throgh hole heated 60 Watt vaccum pump desoldering wond on there with a micro torch off the side of the tip to give it a boost... The temp regularor in the station throdles back to that really didn't help. So I got out a old radio shack 40 watt desoldering tool with a hand bubble on it, placed it on the lead and applied the micro torch to the side of the tip, it was able to soften the solder enough to move the pin around but not enough to really blow or suck the solder out, after all that work, all it did was remove the surface solder but not in the via. Yes, by all accounts, it is Silver solder, the stuff that normall requires a torch to apply. I assume they prepped the board using the silver solder paste and then hit it with a super hot iron or something close to it. Btw, I even tried a 300 watt iron which did soften it but the tip is so large that I just could not do much with it. Anyone got ideas in removing this rectifier moduale ? I did think about cutting the the leads to the surface and drilling them out but I think make cause a via issue because some of the legs do have voids in them from where I was successful in removing some of the solder.. Anyone have somke ideas? |
| Jon Elson <jmelson@wustl.edu>: Feb 07 05:02PM -0600 M Philbrook wrote: > side of the tip, it was able to soften the solder enough to move the pin > around but not enough to really blow or suck the solder out, after all > that work, all it did was remove the surface solder but not in the via. If you can get the solder to melt, then dilute it with tin/lead solder and it will lower the melting point. Then, more traditional methods might work. But, most of the components are likely trashed by the heat. Jon |
| dplatt@coop.radagast.org (Dave Platt): Feb 07 03:23PM -0800 In article <MPG.34e54c53bbe8681c98a0ab@news.eternal-september.org>, >them out but I think make cause a via issue because some of the legs do >have voids in them from where I was successful in removing some of the >solder.. Try heating it up and applying some fresh, lower-melting-point solder... 63/37 comes to mind, or even ChipQuik (which might be excessively expensive for this). A drop of rosin flux, first, might be a good idea. There's a fair chance that the new solder, once liquid, will begin to dissolve away the high-temperature silver, forming a eutectic whose melting point will still be within the range of your iron or torch. Vacuum-bulb away the eutectic, and repeat the operation to dissolve the next layer of silver. |
| "pfjw@aol.com" <pfjw@aol.com>: Feb 07 06:51PM -0800 Desperate needs call for desperate measures. Cut off the unit using either a fine Dremel wheel, or a hand file. Rinse everything with 99% isopropyl alcohol to remove the scarf. Then remove the individual legs with a toothpick and enough heat - follow the suggestions using 37/63 solder - and a solder sucker. And, with patience, there you are. Peter Wieck Melrose Park, PA |
| Jeff Liebermann <jeffl@cruzio.com>: Feb 07 09:29AM -0800 On Wed, 7 Feb 2018 09:18:57 -0000 (UTC), gregz <zekor@comcast.net> wrote: >Naphtha. It evaporates slower than some other solvents. The 5% oily >solution remains for some time. Flammable but not conductive. >Greg Reverse engineering Deoxit is problematic because the formula has changed over the years (starting with Cramoline) and because there are multiple mutations sold under the Deoxit name. There's now a Deoxit grease. Even so, I can assure you that gasoline is not used (it evaporates and you would smell it). The spray type is mostly "mineral spirits" or "naphtha". The "active ingredient" is some kind of acidic oxide remover, such as oleic acid (because it is food safe): <http://store.caig.com/s.nl/it.I/id.66/.f> "Formulation: 5% DeoxIT® (active ingredient), 75% odorless mineral spirits (carrier solvent), 20% propellant Formulation contains petroleum naphtha (odorless mineral spirits) solvent, and is briefly flammable (until solvent evaporates within 2-3 minutes). It's slower to evaporate, providing flushing action to remove surfaces dirt, grease and other contaminants. Is ideal for connectors and components removed from equipment or those that are easily accessible. It is safe on plastics. When in doubt, always test for compatibility, especially vintage equipment with aging ABS plastic(s)." Note the $150 for 7.4ml price tag for Deoxit Gold Pro GX3. <http://store.caig.com/s.nl/it.A/id.2847/.f> "Shields Against Noise and RFI" Ummm... right. -- 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 |
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