I use a Weller butane soldering iron with a hot-air blower tip. It works very well, and I think I paid $65 for it, with a set of interchangeable tips - blowtorch (don't use that one for soldering), hot air, fine and not-so-fine soldering tips, and a hot knife.
For prototypes, before I invest in a solder stencil, I use a veterinary syringe from a local farm supply store (Tractor Supply, there might be one near you if you're in the USA) with a #22 needle for fine-pitch pads. I use a dremel tool with a cutoff wheel to cut the needle off square for safety, and I cut it pretty short to make it easier to force the solder paste out. It still takes practice to avoid getting too much paste on the pads, but it can be done. One trick I really like is to use an electric skillet or griddle as a hot plate. Put the PCB (or PCB's if you are working on more than one) on the griddle, and use an infrared thermomter (can be found for less than $20 at Harbor Freight Tools, and probably other places as well) to monitor the temperature. When it gets close to the melting point, use the hot-air blower to take it the rest of the way. Works great, and the use of a "hot-plate" facilitates unsoldering. The wick technique scares me because of the risk of lifting a pad and ruining the PCB. I've done that a few times. Also, if you use a no-clean solder paste, it doesn't leave baked-on flux. I use Amtech LF-4300, which is also water-soluble. --- In [email protected], ward <ya...@...> wrote: > > I use one of these dam hot air guns. Absolutely worth the price. > > I don't use it for fine pitch ICs, I use the slobber-n-wick approach > because I find applying very small amounts of solder paste nearly > impossible. > > I have seen small solder balls between the pins. I simply slobber > on more solder and wick it back off. The vast majority of the time > it works fine. If it doesn't it is because the solder balls are > imbedded > in baked flux. I use alcohol and a stiff tooth brush to clean them out. > > Done. > > For everything else I use a diluted form of solder paste... > apply the paste > place the parts > bake the assembly at 80c for 20 minutes (drive > off the volatiles of the solder paste) > 'reflow' using the hot air gun. > > Works beautifully and is significantly faster than through hole. > Took me several projects to adapt to surface mount. I threw all > my through hole parts away so I wouldn't be tempted to design > with them again. > > Seriously. Use surface mount a few times and you'll love it. > Make the investment in a hot air gun of some sort, you'll have > more success earlier and make the transition less painful. > > ward > ae6ty > > > On Jan 28, 2010, at 3:28 PM, Dave Wade wrote: > > > I have built both an Elector SDR and a USA QRP Club DDS board, both of > which > have surface mount components on. I have also repaired some circuits > with > surface mount components. I have a hot air gun like this:- > > http://www.pcb-soldering.co.uk/index.php?target=products&product_id=37 > > And while its only really essential for removing SMD ICs, at which its > very > good, I personally think it makes a much better job of "R"s and "C"s > that an > Iron and Solder. So if you are going to do any volume of SMD work I > would > highly recommend one, but its not essential and don't be put of if you > don't > have one... > > Dave > G4UGM > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf Of Dave - WB6DHW > > Sent: 28 January 2010 22:19 > > To: [email protected] > > Subject: Re: [soft_radio] Re: LD-1 Discussion on > > Garage-shoppe.com Blog > > > > > > Peter: > > The procedure is to solder the ssop pins and not worry > > about shorts. > > Then use solder wick to remove the shorts. Easier than it > > sounds. Many > > have done this with IC's with .020" pitch. > > > > Dave - WB6DHW > > <http://wb6dhw.com> >
