Success, I was hoping my amateurish suggestion would provoke someone with more experience to chip in.
I used a el-cheep-o heat gun held several 6 inches or so from the board to provide more gradual and dispersed heating to prevent heat shocking the components. Though when I compare it to seeing boards coming out of a reflow oven it seams a little tame. On 9/18/03 12:02 PM, "Jeff Walther" <[EMAIL PROTECTED]> wrote: >> Date: Thu, 18 Sep 2003 01:55:58 -0400 >> From: Benjamin Berry <[EMAIL PROTECTED]> > >> I don't know what it would do to the rest of the components but I've found 5 >> minutes of exposure to a heat gun ( for paint stripping ) to loosen solder >> right up. Works great on multi pin through hole components. > > I like that method, but there are some things to watch out for. > > First, know your heat gun. A professional strength heat gun may burn > your board, because it seems to put out a much higher temperature > than other guns. I use a Milwaukee brand heat gun I bought at Home > Depot which has a dial on the back for adjusting temperature. I > don't know how good this one would be for stripping much paint, but > it's great for desoldering. > > Second, limit your time. I've found that most through-hole and > surface mount stuff will come off in one to three minutes of > exposure, but it varies greatly and, of course, depends on the > temperature setting on the heat gun. So, when I'm doing through-hole > stuff, I poke at the solder with a dental pick every fifteen seconds > or so. When the dental pick starts penetrating the solder, it's > almost done. When I'm doing a large surface mount chip, I gently > (very very gently) pry at a corner of the chip with the dental pick, > until it lifts with next to no force. I usually put a digital watch > nearby so that I know how long I've been heating the board. > > Third, don't blow away neighboring components. The first time I > used a heat gun on a circuit board was on a PCC Power 120 with a bad > CPU. I got the CPU off okay, but I literally blew away half a dozen > surrounding components. They came loose and flew away with the hot > air. I spent three months trying to get a detailed look at another > Power 120 so I could figure out what went where*. Cover > neighboring components with modeling clay so that they don't blow > away. It only takes a thin layer, so a small box of modeling clay > will last you most of forever. It's not a terrible idea to make a > high resolution scan before starting, but that won't show you the > tiny markings on a surface mount resistor. > > Oh, and having a ~5x magnifying cup handy doesn't hurt either. > That's the kind you can hold in place with the skin around your eye. > It gives you magnification on your work with your hands free. This > useful for soldering and usually not needed for desoldering. One of > those lamps/magnifiers on an arm is probably better, but they can be > expensive, and the magnifying cups are under $5 in the jewelry > section of Ebay. Oh, but your depth perception goes, so be careful > with the soldering pencil. I had a very hard to explain burn mark > across my nose for a while... > > * I finally managed it at the PCC going out of business auction. A > really nice security guard there let me open one of the Power 120s up > and sit there on the floor and copy down the values of the various > resistors and such that I needed. He even moved one of the heavy > floor lamps over to provide light for me. That was a really nice > guy. > > Jeff Walther > -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
